Publications by authors named "Xingdao He"

25 Publications

  • Page 1 of 1

Optical microfiber sensor for detection of Ni ions based on ion imprinting technology.

Analyst 2022 Jan 17;147(2):358-365. Epub 2022 Jan 17.

Jiangxi Engineering Laboratory for Optoelectronics Testing Technology, Nanchang 330063, China.

The detection of ultralow heavy metal ion concentration is highly significant for protecting human health and maintaining the stability of the ecological environment. Herein, a microfiber interferometer chemical sensor for the detection of Ni ions was proposed and experimentally demonstrated. The microfiber sensor was coated with an ion-imprinted chitosan polymer using Ni as the template ion. Experimental results demonstrated a high sensitivity of 0.0454 nm nM for detect-ing Ni in the range of 10 nM to 100 nM, and a limit of detection as low as 6.5 nM was achieved. The microfiber sensor was verified using two different non-template heavy ions, Cu and Cr, and was determined to be highly selective to Ni. Furthermore, the regeneration characteristics of the sensor were experimentally assessed by three repeated adsorption-desorption cycles, and the results showed that the microfiber sensor achieved good stability without a significant loss in sensitivity. Besides, the detecting tests of Ni in lake water and industrial sewage samples demonstrated the sensor's practical application. This proposed sensor has the advantages of simple configuration, high selectivity and sensitivity, fast response, and the ability to serve as a platform for water safety monitoring and remote sensing.
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http://dx.doi.org/10.1039/d1an01982aDOI Listing
January 2022

Quantification of biomechanical properties of human corneal scar using acoustic radiation force optical coherence elastography.

Exp Biol Med (Maywood) 2022 03 3;247(6):462-469. Epub 2021 Dec 3.

Key Laboratory of Opto-Electronic Information Science and Technology of Jiangxi Province and Jiangxi Engineering Laboratory for Optoelectronics Testing Technology, Nanchang Hangkong University, Nanchang 330063, P. R. China.

Biomechanical properties of corneal scar are strongly correlated with many corneal diseases and some types of corneal surgery, however, there is no elasticity information available about corneal scar to date. Here, we proposed an acoustic radiation force optical coherence elastography system to evaluate corneal scar elasticity. Elasticity quantification was first conducted on rabbit corneas, and the results validate the efficacy of our system. Then, experiments were performed on an human scarred cornea, where the structural features, the elastic wave propagations, and the corresponding Young's modulus of both the scarred region and the normal region were achieved and based on this, 2D spatial distribution of Young's modulus of the scarred cornea was depicted. Up to our knowledge, we realized the first elasticity quantification of corneal scar, which may provide a potent tool to promote clinical research on the disorders and surgery of the cornea.
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http://dx.doi.org/10.1177/15353702211061881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8943333PMC
March 2022

Influence of temperature-salinity-depth structure of the upper-ocean on the frequency shift of Brillouin LiDAR.

Opt Express 2021 Oct;29(22):36442-36452

Brillouin-based LiDAR is an alternative remote sensing technique for measuring the distribution profiles of temperature, salinity, and sound speed in the upper ocean mixed layer. Its principle is based on the dependence of Brillouin frequency shift on the temperature, salinity, and depth of ocean. Therefore, it is necessary to investigate the effect of various seawater parameters on Brillouin frequency shift for ocean remote sensing by using the Brillouin LiDAR. Here we theoretically and experimentally investigate the influence of temperature, salinity, and pressure (depth) of seawater on Brillouin frequency shift in the upper ocean for the first time. Numerical simulations of the distribution profiles of temperature, salinity, and Brillouin frequency shift in the upper-ocean mixed layers of East China Sea and South China Sea were performed, respectively, by employing the Brillouin equations and the World Ocean Atlas 2018 (WOA18). A special ocean simulation system was designed to carry out the stimulated Brillouin scattering (SBS) experiments for validating the numerical simulations. The results show that the seawater temperature is the most important factor for the Brillouin frequency shift in the upper-ocean mixed layer compared with the salinity and pressure. At the same salinity and pressure, the frequency shift increases by more than 10 MHz for every 1 °C increase in temperature. Also, the differences of Brillouin frequency shift between experimental and theoretical values at the same parameter conditions were analyzed. The experimental results coincide well with the theoretical simulations. This work is essential to future applications of Brillouin LiDAR in remote sensing of the temperature, salinity, or sound velocity profiles of ocean.
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http://dx.doi.org/10.1364/OE.443151DOI Listing
October 2021

A Laser-Locked Hollow Waveguide Gas Sensor for Simultaneous Measurements of CO Isotopologues with High Accuracy, Precision, and Sensitivity.

Anal Chem 2021 11 12;93(46):15468-15473. Epub 2021 Nov 12.

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

A laser frequency-locked hollow waveguide (HWG) gas sensor is demonstrated for simultaneous measurements of three isotopologues (CO, CO, and OCO) using wavelength modulation spectroscopy with a 2.73 μm distributed feedback laser. The first harmonic (1) signal at the sampling point where the peak of the second harmonic (2) signal was located was employed as the locking point to lock the laser frequency to the transition center of CO, while the absorption lines of CO and OCO were being scanned. Continuous measurements of the three isotopologues of 4.7% CO samples over 103 min under free running and frequency locking conditions were performed. The measurement accuracy and precision of the three isotopologues achieved under the frequency locking condition were at least 3 times and 1.3 times better than those obtained under the free running condition, respectively. The Allan variance plot of the developed laser-locked HWG gas sensor shows a detection limit of 0.72‰ for both δC and δO under the frequency locking condition with a long stability time of 766 s. This study demonstrated the high potential of a novel human breath diagnostic sensor for medical diagnostic with high accuracy, precision, and sensitivity and without frequently repeated calibration.
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http://dx.doi.org/10.1021/acs.analchem.1c03482DOI Listing
November 2021

Global Evolution of Skeletal Muscle Tissue Engineering: A Scientometric Research.

Tissue Eng Part C Methods 2021 09;27(9):497-511

School of Physical Education, China University of Geosciences, Wuhan, P.R. China.

Skeletal muscle tissue engineering (SMTE) is of great significance in the study of skeletal muscle physiology and pathology, which could be used in skeletal muscle graft. The scientometric analysis of SMTE can help researchers to quickly understand the evolutive history, status, novelties, and trend of this field. In this study, we performed a scientometric study that can be used to construct and visualize networks of SMTE using VOSviewer. A total of 1384 documents published between 1994 and 2020 were retrieved and analyzed. Our results showed that number of publications in SMTE has increased slowly from 1994 to 2014 and has increased rapidly from 2015 to 2020. The geographical distribution of publications in terms of total publications about SMTE is concentrated in Europe and the United States. The most productive institution was University of Michigan, while Harvard University and the University of Pittsburgh were ranked the second and third places. SMTE influenced a wide spectrum of disciplines, including and . In addition, the research hotspot of SMTE was expanding from seed cells to the combination with advanced strategies (electrostatic spinning, bioprinting, and materials) for emulating the highly bionic engineered skeletal muscle tissues. This study provided a unique perspective for understanding the history and trends of SMTE, which could help to promote the rapid development of the field. Impact statement Skeletal muscle tissue engineering (SMTE), which acts as an important branch of tissue engineering, hold a great promise in the study of skeletal muscle physiology and pathology. The field of SMTE has developed rapidly in recent decades while still lacking studies based on scientometric methods. This article provided the first scientometric study of SMTE from development trends and evolution of the field. The results indicated that the field of SMTE was experiencing rapid growth and had a significant impact on multiple fields, particularly in and .
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http://dx.doi.org/10.1089/ten.TEC.2021.0156DOI Listing
September 2021

Simulated biomechanical effect of aspheric transition zone ablation profiles after conventional hyperopia refractive surgery.

Math Biosci Eng 2021 03;18(3):2442-2454

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

We studied the effects of the aspheric transition zone on the optical wavefront aberrations, corneal surface displacement, and stress induced by the biomechanical properties of the cornea after conventional laser in situ keratomileusis (LASIK) refractive surgery. The findings in this study can help improve visual quality after refractive surgery. Hyperopia correction in 1-5D was simulated using five types of aspheric transition zones with finite element modeling. The algorithm for the simulations was designed according to the optical path difference. Wavefront aberrations were calculated from the displacements on the anterior and posterior corneal surfaces. The vertex displacements and stress on the corneal surface were also evaluated. The results showed that the aspheric transition zone has an effect on the postoperative visual quality. The main wavefront aberrations on the anterior corneal surface are defocus, y-primary astigmatism, x-coma, and spherical aberrations. The wavefront aberrations on the corneal posterior surface were relatively small and vertex displacements on the posterior corneal surface were not significantly affected by the aspheric transition zone. Stress analysis revealed that the stress on the cutting edge of the anterior corneal surface decreased with the number of aspheric transition zone increased, and profile #1 resulted in the maximum stress. The stress on the posterior surface of the cornea was more concentrated in the central region and was less than that on the anterior corneal surface overall. The results showed that the aspheric transition zone has an effect on postoperative aberrations, but wavefront aberrations cannot be eliminated. In addition, the aspheric transition zone influences the postoperative biomechanical properties of the cornea, which significantly affect the postoperative visual quality.
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http://dx.doi.org/10.3934/mbe.2021124DOI Listing
March 2021

Effects of temperature and pressure on the threshold value of SBS LIDAR in seawater.

Opt Express 2020 Dec;28(26):39038-39047

Effects of temperature and pressure on the threshold value of stimulated Brillouin scattering (SBS) in seawater were analyzed theoretically and experimentally. Theoretically, the change of threshold value of SBS versus the ocean depth was simulated based on the International Thermodynamic Equation of Seawater-2010 (TEOS-10) and the World Ocean Atlas 2013 (WOA13). Experimentally, an ocean temperature and pressure simulator (OTPS) was designed to measure the threshold value of SBS through simulating the changes of temperature and pressure of seawater in 0∼1000 meters. The theoretical and experimental results exhibit that the threshold value of SBS decreases with the increase of temperature at the same seawater pressure and increases with the increase of pressure at the same seawater temperature. The results imply that the SBS process is more likely to occur in upper seawater of lower-latitude areas. The theoretical and experimental results are helpful for remote sensing in ocean using the SBS LIDAR.
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http://dx.doi.org/10.1364/OE.413157DOI Listing
December 2020

Quantification of iris elasticity using acoustic radiation force optical coherence elastography.

Appl Opt 2020 Dec;59(34):10739-10745

Careful quantification of the changes in biomechanical properties of the iris can offer insight into the pathophysiology of some ocular diseases. However, to date there has not been much information available regarding this subject because clinical detection for iris elasticity remains challenging. To overcome this limitation, we explore, for the first time to our knowledge, the potential of measuring iris elasticity using acoustic radiation force optical coherence elastography (ARF-OCE). The resulting images and shear wave propagation, as well as the corresponding shear modulus and Young's modulus from ex vivo and in vivo rabbit models confirmed the feasibility of this method. With features of noninvasive imaging, micrometer-scale resolution, high acquisition speed and real-time processing, ARF-OCE is a promising method for reconstruction of iris elasticity and may have great potential to be applied in clinical ophthalmology with further refinement.
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http://dx.doi.org/10.1364/AO.406190DOI Listing
December 2020

Real-Time Monitoring of C- and O-Isotopes of Human Breath CO Using a Mid-Infrared Hollow Waveguide Gas Sensor.

Anal Chem 2020 10 9;92(19):12943-12949. Epub 2020 Sep 9.

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

Real-time measuring of CO isotopes (CO, CO, and OCO) in exhaled breath using a mid-infrared hollow waveguide gas sensor incorporating a 2.73 μm laser was proposed and demonstrated for the first time based on calibration-free wavelength modulation spectroscopy. The measurement precisions for δC and δO were, respectively, 0.26 and 0.57‰ for an integration time of 131 s by Allan variance analysis. These measurement precisions achieved in the present work were at least 3.5 times better than those reported using direct absorption spectroscopy and 1.3 times better than those obtained by calibration-needed wavelength modulation absorption spectroscopy. Continuous measurement of three isotopes in the breathing cycle was performed. Alveolar gas from the expirogram was identified, and the C/C and O/O ratios were found to be almost constant during the alveolar plateau, which enables optimization of breath sampling and provides accurate information on metabolic processes. The C/C and O/O isotope ratios at the alveolar plateau of five breath cycles were averaged, yielding δC and δO values of (-24.3 ± 3.4) and (-30.7 ± 2.6) ‰, respectively. This study demonstrates the feasibility of real-time analysis of C- and O-isotopes of human breath CO in clinical applications and shows its potential for diagnosing respiratory-related diseases with high sensitivity, selectivity, and specificity.
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http://dx.doi.org/10.1021/acs.analchem.0c01586DOI Listing
October 2020

Real-time measurement of CO isotopologue ratios in exhaled breath by a hollow waveguide based mid-infrared gas sensor.

Opt Express 2020 Apr;28(8):10970-10980

A hollow waveguide (HWG) based mid-infrared gas sensor using a 2.73 µm distributed feedback (DFB) laser was developed for simultaneously measuring the concentration changes of the three isotopologues CO, CO, and OCO in exhaled breath by direct absorption spectroscopy, and then determining the CO/CO isotope ratio (δC) and OCO/CO isotope ratio (δO). The HWG sensor showed a fast response time of 3 s. Continuous measurement of δC and δO in the standard CO sample with known isotopic ratios for ∼2 h was performed. Precisions of 2.20‰ and 1.98‰ for δC and δO respectively at optimal integration time of 734 s were estimated from Allan variance analysis. Accuracy of -0.49‰ and -1.20‰ for δC and δO, respectively, were obtained with comparison to the values of the reference standard. The Kalman filtering method was employed to improve the precision and accuracy of the HWG sensor while maintaining high time resolution. Precision of 5.45‰ and 4.88‰ and the accuracy of 0.21‰ and -1.13‰ for δC and δO, respectively, were obtained at the integration time of 0.54 s with the application of Kalman filtering. The concentrations of CO, CO and OCO in breath cycles were measured and processed by Kalman filtering in real time. The measured values of δO and δC in exhaled breath were estimated to be -21.35‰ and -33.64‰, respectively, with the integration time of 1 s. This study demonstrates the ability of the HWG sensor to obtain δC and δO values in breath samples and its potential for immediate respiratory monitoring and disease diagnosis.
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http://dx.doi.org/10.1364/OE.385103DOI Listing
April 2020

Global Trends of Organoid and Organ-On-a-Chip in the Past Decade: A Bibliometric and Comparative Study.

Tissue Eng Part A 2020 06 31;26(11-12):656-671. Epub 2020 Jan 31.

Department of Biomedical Engineering, Wuhan University School of Basic Medical Sciences, Wuhan, P.R. China.

Organoid and organ-on-a-chip have evolved as two critical but distinct approaches to develop human physiologically and pathologically relevant models. Although rapid progress has been witnessed in the past decade, there is no systematic comparison of their status and trends based on the scientometric analysis. In this study, we performed a comparative study of organoid and organ-on-a-chip using bibliometric methods. A total of 2790 documents published between 2009 and 2018 were retrieved and analyzed. Our results showed that both organoid and organ-on-a-chip had experienced rapid growth in their academic and social impacts and influenced a wide spectrum of disciplines, but with a major distinct focus on Cell Biology and Nanoscience Nanotechnology, respectively. The hotspots of organoid research were expanding from differentiation of Lgr5 stem cells to mechanistic studies of diseases, while the hotspots of the organ-on-a-chip research were transiting from the establishment of microfluidic devices for cell culture to stem cell differentiation and tissue engineering. Interestingly, there was a growing trend of combining organoid with organ-on-a-chip in the last few years. This comparative study presented a unique perspective to understand the evolutive history and future trends of organoid and organ-on-a-chip for emerging human relevant organotypic models. Impact statement Organoid and organ-on-a-chip, which served as emerging human physiologically and pathologically relevant models, hold a great promise to revolutionize the conventional paradigm in basic and clinical research. The fields of organoid and organ-on-a-chip have advanced rapidly over the past decade while lacking comparative studies based on bibliometric methods. This article provided the first scientometric study of these two fields from the unique perspectives of their research hotspots, influencing scientific areas, and global trends. Our bibliometric work will provide a quantitative and timely summary of these two fields for the researchers in the tissue engineering field.
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http://dx.doi.org/10.1089/ten.TEA.2019.0251DOI Listing
June 2020

Acoustic radiation force optical coherence elastography for elasticity assessment of soft tissues.

Appl Spectrosc Rev 2019 25;54(6):457-481. Epub 2018 Jun 25.

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.

Biomechanical properties of soft tissues are important indicators of tissue functions which can be used for clinical diagnosis and disease monitoring. Elastography, incorporating the principles of elasticity measurements into imaging modalities, provides quantitative assessment of elastic properties of biological tissues. Benefiting from high-resolution, noninvasive and three-dimensional optical coherence tomography (OCT), optical coherence elastography (OCE) is an emerging optical imaging modality to characterize and map biomechanical properties of soft tissues. Recently, acoustic radiation force (ARF) OCE has been developed for elasticity measurements of ocular tissues, detection of vascular lesions and monitoring of blood coagulation based on remote and noninvasive ARF excitation to both internal and superficial tissues. Here, we describe the advantages of the ARF-OCE technique, the measurement methods in ARF-OCE, the applications in biomedical detection, current challenges and advances. ARF-OCE technology has the potential to become a powerful tool for elasticity assessment of biological samples in a non-contact, non-invasive and high-resolution nature.
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http://dx.doi.org/10.1080/05704928.2018.1467436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6867804PMC
June 2018

Ultrasensitive biosensor based on magnetic microspheres enhanced microfiber interferometer.

Biosens Bioelectron 2019 Dec 6;145:111563. Epub 2019 Aug 6.

National Engineering Laboratory for Destructive Testing and Optoelectronic Sensing Technology and Application, Nanchang HangKong University, Nanchang, 330063, China; Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne, NE1 8ST, United Kingdom. Electronic address:

A critical barrier for the successful development of fiber sensors for bio-chemical processes is their limitedly improved sensitivity, restricted by the sensor structural design. To solve this, in this paper, a novel concept was proposed using functionalised modified magnetic microspheres (MMSs) to "amplify" the effect of target bio-chemical analytes to significantly improve the fiber sensor's sensitivity, which has been demonstrated using human chorionic gonadotropin (hCG) as an example. Two types of antibody hCG, (β and α, both can specifically bind with hCG), were adhered on the surface of fibre sensor and MMSs respectively. Both hCG and MMSs will be specifically captured by the fibre sensor, where MMSs act as an "amplifier" to improve the sensor sensitivity. Experimentally immunomagnetic detection limit of 0.0001 mIU/mL has been achieved, which is the highest reported so far. This newly developed methodology opens a new direction for sensitivity improvement and could be further explored to applications require ultrahigh sensitivity detections such as earlier medical diagnostics.
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http://dx.doi.org/10.1016/j.bios.2019.111563DOI Listing
December 2019

Stimulated Brillouin scattering in combination with visible absorption spectroscopy for authentication of vegetable oils and detection of olive oil adulteration.

Spectrochim Acta A Mol Biomol Spectrosc 2019 Jan 17;206:320-327. Epub 2018 Aug 17.

Jiangxi Engineering Laboratory for Optoelectronics Testing Technology, Nanchang Hangkong University, Nanchang 330063, China. Electronic address:

Vegetable oils provide high nutritional value in the human diet. Specifically, extra virgin olive oil (EVOO) possesses a higher price than that of other vegetable oils. Adulteration of pure EVOO with other types of vegetable oils has attracted increasing attentions. In this work, a stimulated Brillouin scattering (SBS) combined with visible absorption spectroscopy method is proposed for authentication of vegetable oils and detection of olive oil adulteration. The results provided here have demonstrated that the different vegetable oils and adulteration oils exhibit significant differences in normalized absorbance values of two relevant wavelengths (455 and 670 nm) and frequency shifts of SBS. The normalized absorbance values of all spectra at the two relevant wavelengths of 670 nm and 455 nm linearly decrease with the increase of the adulteration concentration. The Brillouin frequency shifts exponentially increase with the increase of the adulteration concentration. Due to non-destructive and requiring no sample pretreatment procedure, this method can be effectively employed for authentication and detection of oils adulteration.
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http://dx.doi.org/10.1016/j.saa.2018.08.031DOI Listing
January 2019

Coaxial excitation longitudinal shear wave measurement for quantitative elasticity assessment using phase-resolved optical coherence elastography.

Opt Lett 2018 May;43(10):2388-2391

Optical coherence elastography (OCE) is an emerging imaging modality for the assessment of mechanical properties in soft tissues. Transverse shear wave measurements using OCE can quantify the elastic moduli perpendicular to the force direction, however, missing the elastic information along the force direction. In this study, we developed coaxial excitation longitudinal shear wave measurements for quantification of elastic moduli along the force direction using M-scans. Incorporating Rayleigh wave measurements using non-coaxial lateral scans into longitudinal shear wave measurements, directionally dependent elastic properties can be quantified along the force direction and perpendicular to the force direction. Therefore, the reported system has the capability to image elasticity of anisotropic biological tissues.
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http://dx.doi.org/10.1364/OL.43.002388DOI Listing
May 2018

Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses.

Sci Rep 2015 Jul 15;5:11964. Epub 2015 Jul 15.

1] Jiangxi Engineering Laboratory for Optoelectronics Testing Technology, Nanchang Hangkong University, Nanchang, 330063, China [2] Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang, 330063, China.

Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision.
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http://dx.doi.org/10.1038/srep11964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4502513PMC
July 2015

Energy level control: toward an efficient hot electron transport.

Sci Rep 2014 Aug 7;4:5983. Epub 2014 Aug 7.

School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.

Highly efficient hot electron transport represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot electron capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the 'excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot electron transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot electron/hole transport efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.
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http://dx.doi.org/10.1038/srep05983DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4124467PMC
August 2014

Measurement of the D/H, ¹⁸O/¹⁶O, and ¹⁷O/¹⁶O isotope ratios in water by laser absorption spectroscopy at 2.73 μm.

Sensors (Basel) 2014 May 21;14(5):9027-45. Epub 2014 May 21.

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

A compact isotope ratio laser spectrometry (IRLS) instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰) better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated.
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http://dx.doi.org/10.3390/s140509027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4063013PMC
May 2014

Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping.

ACS Appl Mater Interfaces 2014 Jun 29;6(11):8771-81. Epub 2014 May 29.

Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University , Nanchang 330063, People's Republic of China.

Low-temperature solution-processed photovoltaics suffer from low efficiencies because of poor exciton or electron-hole transfer. Inorganic/organic hybrid solar cell, although still in its infancy, has attracted great interest thus far. One of the promising ways to enhance exciton dissociation or electron-hole transport is the doping of lanthanide phosphate ions. However, the underlying photophysical mechanism remains poorly understood. Herein, by applying femtosecond transient absorption spectroscopy, we successfully distinguished hot electron, less energetic electron, hole transport from electron-hole recombination. Concrete evidence has been provided that lanthanide phosphate doping improves the efficiency of both hot electron and "less energetic" electron transfers from donor to acceptor, but the hole transport almost remains unchanged. In particular, the hot electron transfer lifetime was shortened from 30.2 to 12.7 ps, that is, more than 60% faster than pure TiO2 acceptor. Such improvement was ascribed to the facts that the conduction band (CB) edge energy level of TiO2 has been elevated by 0.2 eV, while the valence band level almost remains unchanged, thus not only narrowing the energy offset between CB levels of TiO2 and P3HT, but also meanwhile enlarging the band gap of TiO2 itself that permits one to inhibit electron-hole recombination within TiO2. Consequently, lanthanide phosphate doped TiO2/P3HT bulk-heterojunction solar cell has been demonstrated to be a promising hybrid solar cell, and a notable power conversion efficiency of 2.91% is therefore attained. This work indicates that lanthanide compound ions can efficiently facilitate exciton generation, dissociation, and charge transport, thus enhancing photovoltaic performance.
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http://dx.doi.org/10.1021/am501597kDOI Listing
June 2014

Reply: To PMID 23871556.

J Cataract Refract Surg 2014 May;40(5):850-1

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http://dx.doi.org/10.1016/j.jcrs.2014.02.024DOI Listing
May 2014

Theoretical analysis of wavefront aberration caused by treatment decentration and transition zone after custom myopic laser refractive surgery.

J Cataract Refract Surg 2013 Sep 17;39(9):1336-47. Epub 2013 Jul 17.

Key Laboratory of Nondestructive Test, Ministry of Education, Nanchang Hangkong University, Nanchang, China.

Purpose: To analyze the induced wavefront aberrations caused by treatment decentration and transition zone after custom myopic laser refractive surgery.

Setting: Refractive Surgery Center, Tianjin Eye Hospital & Eye Institute, Tianjin Medical University, Tianjin, China.

Design: Cohort study.

Methods: Wavefront aberration data from potential refractive surgery candidates were used. Based on the preoperative wavefront aberrations, the custom ablation profile was computed. Then, the influence of treatment decentration and especially that of the transition zone on induced wavefront aberrations was studied. The impact of angle mismatch on induced aberrations was analyzed.

Results: Data from 117 eyes (77 patients) were analyzed. The transition zone played a significant role in the influence of decentration on the induced aberrations in refractive surgery. Induced coma and spherical aberration increased rapidly as the lateral translation increased, and coma was significantly larger than other Zernike aberration terms. The induced aberrations from decentration with oblique incidence in the laser ablation profile were less than in the actual laser ablation process for slight subclinical decentration. The induced aberrations were not closely related to the subclinical unmatched angle from eye cyclotorsion. The induced aberrations from lateral translation were correlated with the position vector. The transition zone was designed to smooth the transition from the optical zone to the untreated cornea, and it mainly dominated induced coma and spherical aberration.

Conclusion: To achieve the best postoperative visual performance, the effect of the transition zone in refractive surgery should be taken into account, especially for scotopic pupils.
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http://dx.doi.org/10.1016/j.jcrs.2013.03.020DOI Listing
September 2013

Effect of pupil size on residual wavefront aberration with transition zone after customized laser refractive surgery.

Opt Express 2013 Jan;21(2):1404-16

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

The analysis of the change in residual wavefront aberrations after laser refractive surgery is important for the development of visual correction technology. Based on the ablation profile for wavefront-guided refractive surgery including optical zone and transition zone, the effect of pupil size on residual wavefront aberrations was studied. The research revealed that the optical zone to pupil ratio had a significant influence on the residual wavefront aberrations. The residual spherical aberration and coma were obviously larger than other individual Zernike higher-order terms when pupil diameter was larger than the optical zone size, and they increased rapidly as the pupil size increased. In addition, when the ablation zone diameter was kept constant, the residual higher-order aberrations increased rapidly as the blend coefficient increased for a 6 mm or 7 mm pupil. Furthermore, the residual higher-order aberrations with treatment decentration were distinctly larger than those without decentration. In the achievement of the best postoperative visual performance, the design of ablation profile played a crucial role in decrease of the residual wavefront aberrations after refractive surgery, especially optical zone size and the ablation pattern of transition zone.
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http://dx.doi.org/10.1364/OE.21.001404DOI Listing
January 2013

Experimental investigation on the competition between wideband stimulated Brillouin scattering and forward stimulated Raman scattering in water.

Opt Lett 2012 Jul;37(14):2988-90

Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.

The utilization of a simple focused optical cell to bring to light the competition between wideband stimulated Brillouin scattering (WSBS) and forward stimulated Raman scattering (FSRS) is investigated experimentally. A pulsed, wide bandwidth second-harmonic Nd:YAG laser is used as the pump source. We found that, the competition between WSBS and FSRS is an alternate process, which one dominated depends on the linewidth and energy of the pump laser, focal length, and optical breakdown.
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http://dx.doi.org/10.1364/OL.37.002988DOI Listing
July 2012

Theoretical analysis of wavefront aberration from treatment decentration with oblique incidence after conventional laser refractive surgery.

Opt Express 2010 Oct;18(21):22418-31

1Key Laboratory of Nondestructive Test Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China.

Analysis of induced wavefront aberration after refractive surgery is important in the design of vision correction and the development of visual correction technology. Based on a mathematical model of the anterior corneal surface, the influence of treatment decentration on induced wavefront aberrations was studied by considering oblique incidence. The results revealed that significant coma was induced from the treatment translation, and it was nearly proportional to the translation or corrected refraction of vision correction. The induced aberrations from the lateral translation correlated with the angle formed by the position vector and the astigmatism axis of myopia astigmatism correction. The induced spherical aberration did not relate to a lateral translation of the center of the pupil, but was determined only by the corrected refraction. Additionally, no significant higher-order aberrations were induced from eye cyclotorsion for pure myopia or myopia astigmatism correction. Oblique incidence played an important role in the impact of treatment decentration on the induced aberrations in refractive surgery. The induced coma without considering the oblique incidence was obviously larger than that with it. In order to achieve the best postoperative visual performance, the effect of oblique incidence in refractive surgery should be taken into account, and treatment decentration should be minimized by all means, particularly for high myopia.
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http://dx.doi.org/10.1364/OE.18.022418DOI Listing
October 2010

Evaluation of optical quality in white light from wavefront aberrations for a myopic population of human eyes.

Clin Exp Optom 2009 May 1;92(3):313-9. Epub 2009 Apr 1.

Key Laboratory of Nondestructive Test (Nanchang Hangkong University), Ministry of Education, Nanchang, China.

Purpose: To evaluate optical quality in white light for a myopic population by means of some metrics, such as AreaMTF, VSMTF and EE.

Methods: One hundred and thirteen myopic eyes of 113 subjects were enrolled in this study. The optical quality metrics in white light were computed from the polychromatic PSF, which was calculated as the super-position of the monochromatic PSFs for each wavelength.

Results: The relationship between optical quality and the root mean square (RMS) of higher-order aberrations shows that the values of AreaMTF, VSMTF and EE in white light tend to decrease gradually with the increase of RMS. When RMS maintains a constant value, the optical quality varies greatly among eyes. By partial correlation analysis and controlling the impact of total RMS of higher-order aberrations, the association between the percentage of third-order aberrations (in total higher-order aberration) and optical quality can be made. This shows a positive correlation (p < 0.05), which indicates that the greater the percentage of the third-order aberrations, the better the optical quality, with RMS remaining a constant value. On the contrary, the percentage of fourth-order aberrations and spherical aberrations shows a negative correlation with optical quality.

Conclusions: The fourth-order and spherical aberrations have a greater effect on vision than other order aberrations. The impact of monochromatic aberrations on optical quality is greater than that of chromatic aberrations.
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http://dx.doi.org/10.1111/j.1444-0938.2009.00374.xDOI Listing
May 2009
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