Publications by authors named "Wenbo Du"

24 Publications

  • Page 1 of 1

Effect of the CaMgZn Phase on the Corrosion Behavior of Biodegradable Mg-4.0Zn-0.2Mn-Ca Alloys in Hank's Solution.

Materials (Basel) 2022 Mar 11;15(6). Epub 2022 Mar 11.

Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.

The effect of the CaMgZn phase on the corrosion behavior of biodegradable Mg-4.0Zn-0.2Mn-Ca (ZM-xCa, x = 0.1, 0.3, 0.5 and 1.0 wt.%) alloys in Hank's solution was investigated with respect to phase spacing, morphology, distribution and volume fraction. With the increase in Ca addition, the volume fraction of the CaMgZn phase increased from 2.5% to 7.6%, while its spacing declined monotonically from 43 μm to 30 μm. The Volta potentials of secondary phases relative to the Mg matrix were measured by using scanning kelvin probe force microscopy (SKPFM). The results show that the Volta potential of the intragranular spherical CaMgZn phase (+109 mV) was higher than that of the dendritic CaMgZn phase (+80 mV). It is suggested that the CaMgZn acted as a cathode to accelerate the corrosion process due to the micro-galvanic effect. The corrosion preferred to occur around the spherical CaMgZn phase at the early stage and developed into the intragranular region. The corrosion rate increased slightly with increasing Ca content from 0.1 wt.% to 0.5 wt.% because of the enhanced micro-galvanic corrosion effect. The decrease in the phase spacing and sharp increase in the secondary phase content resulted in a dramatic increase in the corrosion rate of the ZM-1.0Ca alloy.
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http://dx.doi.org/10.3390/ma15062079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8955503PMC
March 2022

Bathochromic-Shifted Emissions by Postfunctionalization of Nonconjugated Polyketones.

ACS Appl Mater Interfaces 2021 Dec 2;13(49):59288-59297. Epub 2021 Dec 2.

School of Materials Science and Engineering, PCFM Lab, GD HPPC Lab, Sun Yat-sen University, Guangzhou 510275, China.

Most nontraditional intrinsic luminescent (NTIL) polymers currently show blue fluorescence. Tuning the emission color of NTIL polymers is of fundamental importance for their applications, but it still remains a scientific challenge. Herein, we initially develop an efficient strategy for bathochromic shifting of NTIL polymers by through-space acceptor-donor charge transfer between the in chain and the side chain. A variety of functionalized polyketones (FPK-R; where R = H, Ph, Me, Bu, F, and Cl) with furan rings built into the polymer chain were prepared by the Paal-Knorr reaction. FPK-R polymers showed bright and bathochromic-shifted fluorescence compared with their counterparts. The emission color could be tuned by changing the postfunctionalization conversion and varying the styrenic monomer substituent. Experimental and theoretical investigations revealed that the color tunability originated from enhanced through-space charge transfer between the side chain phenyl and the in chain furan rings.
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http://dx.doi.org/10.1021/acsami.1c18822DOI Listing
December 2021

Nanofiber Composite Coating with Self-Healing and Active Anticorrosive Performances.

ACS Appl Mater Interfaces 2021 Dec 19;13(48):57880-57892. Epub 2021 Nov 19.

Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China.

Synergetic self-healing anticorrosion behaviors, by forming a self-assembly protective layer and repairing coating passive barrier, exhibit great potential in handling the notorious metal corrosion phenomenon. Herein, we developed a nanofiber-supported anticorrosion coating with synergistic protection effects of both self-healing and active corrosion inhibition, via a facile electrospinning combined coating technique. Polycaprolactone (PCL) nanofiber integrated with 2-mecapobenzothiazole-loaded halloysite nanotubes (HNTs-MBT) is directly deposited on the surface of metal substrate, forming an interconnected fiber network framework. The encapsulated corrosion inhibitor MBT can be released by a pH-triggered manner to realize instant corrosion protections. Additionally, coating defects could be repeatedly repaired by continuous polymer fiber upon heat treatment and the anticorrosion efficiency effectively remained, even after three cycles of damage-healing. Moreover, the repaired coating also exhibited durable anticorrosion performance, mainly attributed to the synergetic effects of both thermal-triggered bulk healing and active corrosion inhibition. This type of dual-functional coating provides efficient anticorrosive performances and may show great promise in long-term corrosion protection.
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http://dx.doi.org/10.1021/acsami.1c16052DOI Listing
December 2021

Dynamic activity chain pattern estimation under mobility demand changes during COVID-19.

Transp Res Part C Emerg Technol 2021 Oct 25;131:103361. Epub 2021 Aug 25.

School of Electronic and Information Engineering, Beihang University, Beijing 100191, PR China.

During the coronavirus disease 2019 pandemic, the activity engagement and travel behavior of city residents have been impacted by government restrictions, such as temporary city-wide lockdowns, the closure of public areas and public transport suspension. Based on multiple heterogeneous data sources, which include aggregated mobility change reports and household survey data, this paper proposes a machine learning approach for dynamic activity chain pattern estimation with improved interpretability for examining behavioral pattern adjustments. Based on historical household survey samples, we first establish a computational graph-based discrete choice model to estimate the baseline travel tour parameters before the pandemic. To further capture structural deviations of activity chain patterns from day-by-day time series, we define the activity-oriented deviation parameters within an interpretable utility-based nested logit model framework, which are further estimated through a constrained optimization problem. By incorporating the long short-term memory method as the explainable module to capture the complex periodic and trend information before and after interventions, we predict day-to-day activity chain patterns with more accuracy. The performance of our model is examined based on publicly available datasets such as the 2017 National Household Travel Survey in the United States and the Google Global Mobility Dataset throughout the epidemic period. Our model could shed more light on transportation planning, policy adaptation and management decisions during the pandemic and post-pandemic phases.
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http://dx.doi.org/10.1016/j.trc.2021.103361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418203PMC
October 2021

Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO Single Crystal.

Materials (Basel) 2021 Aug 9;14(16). Epub 2021 Aug 9.

National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China.

The ferroelectric domain surface charge dynamics after a cubic-to-tetragonal phase transition on the BaTiO single crystal (001) surface was directly measured through scanning probe microscopy. The captured surface potential distribution shows significant changes: the domain structures formed rapidly, but the surface potential on polarized domain was unstable and reversed its sign after lengthy lapse; the high broad potential barrier burst at the corrugated domain wall and continued to dissipate thereafter. The generation of polarization charges and the migration of surface screening charges in the surrounding environment take the main responsibility in the experiment. Furthermore, the domain wall suffers large topological defects and polarity variation, resulting in domain wall broadening and stress changes. Thus, the domain wall has excess energy and polarization change is inclined to assemble on it. The potential barrier decay with time after exposing to the surrounding environment also gave proof of the surface screening charge migration at surface. Thus, both domain and domain wall characteristics should be taken into account in ferroelectric application.
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http://dx.doi.org/10.3390/ma14164463DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8398434PMC
August 2021

Does industrial collaborative agglomeration improve environmental efficiency? Insights from China's population structure.

Environ Sci Pollut Res Int 2022 Jan 20;29(4):5072-5091. Epub 2021 Aug 20.

School of Public Administration, Dongbei University of Finance & Economics, No. 217 Jianshan Street, Dalian, 116025, Liaoning, China.

Nowadays, the development of green economy and the improvement of environmental efficiency have been a hotspot in both academia and industry. Especially, the effect of the collaborative agglomeration of manufacturing and productive services industries on environmental efficiency has drawn attention from Chinese policymakers, during a critical period of industrial transformation and upgrading and ecological civilization construction in China. However, few studies have explored whether and how industrial collaborative agglomeration affects environmental efficiency based on population structure perspective. To bridge this gap, using the methods of the stochastic frontier approach (SFA), the moderating effect of population structure, and the spatial effect, and employing the panel data of 66 cities in eastern China during 2009-2018, this paper studies the effect of industrial collaborative agglomeration on environmental efficiency and measure the fluctuates of influence including population structure. The results show that industrial collaborative agglomeration has the effect of improving environmental efficiency, and both of them have strong spatial spillover effect. Direct effect of the industrial collaborative agglomeration is more significant positive than indirect effect. It indicates that the environmental efficiency is affected by the industrial collaborative agglomeration in both the local region and neighboring regions. In addition, population density, aging and quality play a positive moderate role by strengthening the spillover effect of industrial collaborative agglomeration, while the moderating effect of population urbanization is not significant. Then, the recommendations and policy implications to improve environmental efficiency are put forward based on the research results: optimizing the coordinated governance system of regional ecological environment, accelerating the innovation of industrial value chain, and promoting the sustainable development of industry and ecology with the advantage of population structure.
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http://dx.doi.org/10.1007/s11356-021-15618-3DOI Listing
January 2022

Failure Analysis of the Tree Column Structures Type AlSi10Mg Alloy Branches Manufactured by Selective Laser Melting.

Materials (Basel) 2020 Sep 8;13(18). Epub 2020 Sep 8.

School of Materials Science and Engineering, North University of China, Taiyuan 030051, China.

AlSi10Mg alloy branches were fabricated by selective laser melting (SLM), and the branches were employed to evaluate their effect on the mechanical properties. When the porous branches were compressed along its building direction, the tree column structures-type AlSi10Mg alloy branches collapsed twice, which had typical elastic, shear, collapse, and densification stages. The compressive stress concentration at the interface between the support and the porous body caused the fracture of the tree column structures-type AlSi10Mg alloy branches. The fracture surface indicated that the prepared tree-type branches were distributed with different shapes of dimples, and the Si content inside the dimples was higher than that of the edge. The morphology of the Al-Si eutectic structure formed by SLM and the stress concentration at the Al/Al-Si-eutectic interface affected the fracture morphology and Si content distribution.
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http://dx.doi.org/10.3390/ma13183969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7560194PMC
September 2020

Predictability of real temporal networks.

Natl Sci Rev 2020 May 10;7(5):929-937. Epub 2020 Feb 10.

School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.

Links in most real networks often change over time. Such temporality of links encodes the ordering and causality of interactions between nodes and has a profound effect on network dynamics and function. Empirical evidence has shown that the temporal nature of links in many real-world networks is not random. Nonetheless, it is challenging to predict temporal link patterns while considering the entanglement between topological and temporal link patterns. Here, we propose an entropy-rate-based framework, based on combined topological-temporal regularities, for quantifying the predictability of any temporal network. We apply our framework on various model networks, demonstrating that it indeed captures the intrinsic topological-temporal regularities whereas previous methods considered only temporal aspects. We also apply our framework on 18 real networks of different types and determine their predictability. Interestingly, we find that, for most real temporal networks, despite the greater complexity of predictability brought by the increase in dimension, the combined topological-temporal predictability is higher than the temporal predictability. Our results demonstrate the necessity for incorporating both temporal and topological aspects of networks in order to improve predictions of dynamical processes.
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http://dx.doi.org/10.1093/nsr/nwaa015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8288877PMC
May 2020

The Interfacial Characteristics of Graphene/AlC in Graphene/AlSi10Mg Composites Prepared by Selective Laser Melting: First Principles and Experimental Results.

Materials (Basel) 2020 Feb 4;13(3). Epub 2020 Feb 4.

National Key Laboratory for Remanufacturing, Academy of Army Armored Forces, Beijing 100072, China.

The AlC phase was precipitated via a reaction of graphene (Gr) with Al during selective laser melting (SLM). The interfacial nature of the Gr (0001)/AlC (0001) interface was determined using the first-principle calculation. The simulation results showed that the influence of the stacking site on the interfacial structure was limited and the Al-termination interface presented a more stable structure than the C-termination interface. The Al-termination-CH site interface had the largest work of adhesion (6.28 J/m) and the smallest interfacial distance (2.02 Å) among the four interfacial structures. Mulliken bond population analysis showed that the bonding of the Al-termination interface was a mixture of covalent and ionic bonds and there was no chemical bonding in the C-termination interface.
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http://dx.doi.org/10.3390/ma13030702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7040778PMC
February 2020

Circ-PRMT5 promotes gastric cancer progression by sponging miR-145 and miR-1304 to upregulate MYC.

Artif Cells Nanomed Biotechnol 2019 Dec;47(1):4120-4130

Department of Gastrointestinal Surgery, Kunming Medical University Second Hospital, Kunming, Yunnan, China.

Gastric cancer (GC) is a global leading source of cancer-associated deaths. Circular RNAs (circRNAs) are a new type of non-coding RNA and promising biomarkers for diagnosis of multiple diseases such as cancer. Circ-PRMT5 expression was validated in 90 GC patient tissues and 6 different GC cells by qRT-PCR. Sublocalization of circ-PRMT5 in GC cells was determined in isolated nuclear and cytoplasmic RNAs. CircInteractome and miRanda were used to predict binding sites between circ-PRMT5 with micRNAs, and micRNAs with target mRNA. The correlation between genes was determined by the Pearson correlation analysis. The molecular mechanism was demonstrated by RNA precipitation, point mutation, luciferase activity and rescue experiments. Circ-PRMT5 expression was significantly higher in GC than in adjacent normal tissues, and GC patients with circ-PRMT5 high expression had shorter survival times. Functionally, circ-PRMT5 silence inhibited GC cell growth and invasion. Mechanism analysis showed that circ-PRMT5 sponged miR-145/miR-1304 to upregulate MYC expression and GC development. Our findings demonstrated that circ-PRMT5 function as an oncogene in GC patients by targeting miR-145/miR-1304/MYC axis. High circ-PRMT5 expression may provide a poor prognostic indicator of survival in GC patients and targeting circ-PRMT5/miR-145/miR-1304/MYC axis may be a novel therapeutic strategy for GC.
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http://dx.doi.org/10.1080/21691401.2019.1671857DOI Listing
December 2019

An injectable self-healing hydrogel-cellulose nanocrystals conjugate with excellent mechanical strength and good biocompatibility.

Carbohydr Polym 2019 Nov 15;223:115084. Epub 2019 Jul 15.

College of Chemistry and Key Lab of Environment-Friendly Chemistry and Application in Ministry of Education, Xiangtan University, Xiangtan, Hunan Province 411105, China; Key Laboratory of Theoretical Organic Chemistry, Functional Molecule of Ministry of Education, Hunan Provincial Key Laboratory of Controllable Preparation, Functional Application of Fine Polymers, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan, 411201, China. Electronic address:

In this work, a novel strategy for the construction of injectable self-healing nanocomposite (NC) hydrogels dominated by reversible boronic ester bonds was demonstrated. Specifically, NC hydrogels were constructed by the solution-mixing of N,N-dimethylacrylamide-stat-3-acrylamidophenylboronicacid statistical copolymers (PDMA-stat-PAPBA) and poly(glycerolmonomethacrylate) (PGMA) chains grafted cellulose nanocrystals (CNC-g-PGMA). Rheology analysis indicated the as-constructed NC hydrogel displayed about 7-fold increase in the storage modulus with a low CNCs loading level of 1.43 wt% in comparison with PGMA/PDMA-stat-PAPBA hydrogel without CNCs. Furthermore, the mechanical strength of the CNC-g-PGMA/PDMA-stat-PAPBA hydrogel was far superior to that of its PGMA/PDMA-stat-PAPBA/CNCs hydrogel counterpart, in which PGMA chains were not covalently grafted on the surfaces of CNCs. Due to reversible boronic ester bonds cross-linking networks, CNC-g-PGMA/PDMA-stat-PAPBA NC hydrogel exhibited excellent self-healing and injectable properties as well as pH/glucose responsive sol-gel transitions. Good biocompatibility was also demonstrated through in vitro cytotoxicity tests.
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http://dx.doi.org/10.1016/j.carbpol.2019.115084DOI Listing
November 2019

Effective dispersion of multi-walled carbon nanotubes in aqueous solution using an ionic-gemini dispersant.

J Colloid Interface Sci 2018 Feb 31;512:750-757. Epub 2017 Oct 31.

College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China.

A promising ionic-gemini molecule, 4, 4'-di (n-tetradecyl) diphenylmethane disulfate salt (DSDM), is reported for effective dispersion of multi-walled carbon nanotubes (MWCNTs) in aqueous medium in the present investigation. The dispersibility and stability of the DSDM-modified MWCNTs were characterized by UV-vis spectrophotometer, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and zeta potential measurements. The hydrophobic interaction between alky chains and carbon nanotubes as well as the π-π-stacking interaction between benzene rings and carboatomic rings in MWCNTs enables a successful modification of DSDM onto the MWCNT surface. The dispersed MWCNTs individually existed in dispersion with no structural damage, indicating a much better performance than the MWCNTs dispersed by the sodium dodecylbenzene sulfonate (SDBS), a frequently reported single-chain ionic dispersant. Surface potential measurements showed that the DSDM-modified MWCNTs were negatively charged, giving rise to electrostatic repulsion between the MWCNTs in aqueous solution. A better MWCNT dispersion effect was observed with the increase in MWCNT surface potential, and the dispersion with high MWCNT surface potential presents high dispersion stability with no agglomeration appeared for more than 5 months. The magnesium (Mg) matrix composite fabricated based on the DSDM-dispersed MWCNTs demonstrated excellent mechanical properties compared to pure Mg. Our research may provide an alternative way to improve the mechanical properties of composites.
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http://dx.doi.org/10.1016/j.jcis.2017.10.109DOI Listing
February 2018

Cellulose nanocrystals: A layered host candidate for fabricating intercalated nanocomposites.

Carbohydr Polym 2017 Feb 23;157:79-85. Epub 2016 Sep 23.

College of Chemistry, Xiangtan University, Xiangtan 411105, China. Electronic address:

The stacking of cellulose chains along planes and weak intersheet interactions make cellulose nanocrystals (CNCs) promising as a layered host candidate for fabricating intercalated nanocomposites. As a proof-of-concept, we demonstrate the intercalation of alkyls into CNCs through the in situ intercalative chemical reaction between terminal groups of N-octadecyl isocyanates and hydroxyl groups on the (200) planes in CNCs. Results showed that CNCs could intercalate alkyls in a high degree of substitution to form dense brushes on their (200) planes. After intercalation, a significant enlargement of interlayer spacing was observed. Moreover, alkyls were fully extended in all-trans configuration and crystallized in a co-existing organization of α, β and β crystalline forms. This meant that the molecular arrangement in CNCs/alkyl intercalated nanocomposites would involve a bilayer model in which alkyls were in the ordered packing and titled to (200) plane. Furthermore, CNCs/alkyl intercalated nanocomposites possessed increased thermal properties and decreased char residue.
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http://dx.doi.org/10.1016/j.carbpol.2016.09.065DOI Listing
February 2017

Ultrathin, transferred layers of thermally grown silicon dioxide as biofluid barriers for biointegrated flexible electronic systems.

Proc Natl Acad Sci U S A 2016 10;113(42):11682-11687

Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801;

Materials that can serve as long-lived barriers to biofluids are essential to the development of any type of chronic electronic implant. Devices such as cardiac pacemakers and cochlear implants use bulk metal or ceramic packages as hermetic enclosures for the electronics. Emerging classes of flexible, biointegrated electronic systems demand similar levels of isolation from biofluids but with thin, compliant films that can simultaneously serve as biointerfaces for sensing and/or actuation while in contact with the soft, curved, and moving surfaces of target organs. This paper introduces a solution to this materials challenge that combines (i) ultrathin, pristine layers of silicon dioxide (SiO) thermally grown on device-grade silicon wafers, and (ii) processing schemes that allow integration of these materials onto flexible electronic platforms. Accelerated lifetime tests suggest robust barrier characteristics on timescales that approach 70 y, in layers that are sufficiently thin (less than 1 μm) to avoid significant compromises in mechanical flexibility or in electrical interface fidelity. Detailed studies of temperature- and thickness-dependent electrical and physical properties reveal the key characteristics. Molecular simulations highlight essential aspects of the chemistry that governs interactions between the SiO and surrounding water. Examples of use with passive and active components in high-performance flexible electronic devices suggest broad utility in advanced chronic implants.
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http://dx.doi.org/10.1073/pnas.1605269113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5081656PMC
October 2016

Modeling, Control, and Optimization in Aeronautical Engineering.

ScientificWorldJournal 2015 15;2015:979107. Epub 2015 Jun 15.

Centre for Quantum Computation and Intelligent Systems, University of Technology, Sydney, NSW 2007, Australia.

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http://dx.doi.org/10.1155/2015/979107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4485923PMC
January 2016

Selectively-informed particle swarm optimization.

Sci Rep 2015 Mar 19;5:9295. Epub 2015 Mar 19.

Center for Complex Network Research and Department of Physics, Northeastern University, Boston, MA 02115 USA.

Particle swarm optimization (PSO) is a nature-inspired algorithm that has shown outstanding performance in solving many realistic problems. In the original PSO and most of its variants all particles are treated equally, overlooking the impact of structural heterogeneity on individual behavior. Here we employ complex networks to represent the population structure of swarms and propose a selectively-informed PSO (SIPSO), in which the particles choose different learning strategies based on their connections: a densely-connected hub particle gets full information from all of its neighbors while a non-hub particle with few connections can only follow a single yet best-performed neighbor. Extensive numerical experiments on widely-used benchmark functions show that our SIPSO algorithm remarkably outperforms the PSO and its existing variants in success rate, solution quality, and convergence speed. We also explore the evolution process from a microscopic point of view, leading to the discovery of different roles that the particles play in optimization. The hub particles guide the optimization process towards correct directions while the non-hub particles maintain the necessary population diversity, resulting in the optimum overall performance of SIPSO. These findings deepen our understanding of swarm intelligence and may shed light on the underlying mechanism of information exchange in natural swarm and flocking behaviors.
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http://dx.doi.org/10.1038/srep09295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4365407PMC
March 2015

Phase locking of a 275 W high power all-fiber amplifier seeded by two categories of multi-tone lasers.

Opt Express 2011 Apr;19(8):7312-24

College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, HuNan, 410073, China.

Multi-tone radiation is a promising technique to suppress stimulated Brillouin scattering (SBS) effects and improve the ultimate output power of the fiber laser/amplifier. Coherent beam combining of fiber lasers/ amplifiers is another feasible way to increase the output laser power from single gain medium while simultaneously maintaining good beam quality. In this paper, we combine the multi-tone driven all-fiber amplifiers and active phase compensation to demonstrate high power phase locking for coherent beam combining. First, we present the theory of coherent beam combining of multi-tone lasers. Second, we optimize the all-fiber power amplifier oscillator power-amplifier (MOPA) system with high scalability and flexibility based on compact, high efficiency Yb-doped fiber amplifier chains. Then, two categories of multi-tone master oscillators are used to driven the amplifier chains. The first category is two coupled single-frequency lasers and the second is a frequency modulated single-frequency laser. The output powers are all boosted to 275 W without any distinct SBS. Last, phase locking of the amplifier chains are implemented using stochastic parallel gradient descent (SPGD) algorithm. Scaling this configuration to a higher power involves increasing the power per chain and adding the number of amplifier channels.
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http://dx.doi.org/10.1364/OE.19.007312DOI Listing
April 2011

Simultaneous spectrum and coherent combining by active phasing dual two-tone all-fiber MOPA chains.

Opt Lett 2011 Apr;36(8):1338-40

College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, 410073, China.

We present a new approach for simultaneous spectral and coherent combining in a master oscillator power amplifier (MOPA) configuration with active phasing. Spectrally combined single-frequency seed lasers are employed as a master oscillator for the all-fiber power amplifier chain, which provides robust performance suppressing of the stimulated Brillouin scattering effect, while coherent combining of spectrally combined amplifiers with active phase control provides stable in-phase combining, despite the strong phase fluctuation. In experiments, two spectrally combined seed MOPA chains are coherently combined with a total output power of 390 W. The power of the main lobe in the closed loop is two times of that value in the open loop, and visibility of more than 75% of the long-exposure interference pattern at the receiving plane is obtained.
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http://dx.doi.org/10.1364/OL.36.001338DOI Listing
April 2011

Coherent beam combination of 1.08 kW fiber amplifier array using single frequency dithering technique.

Opt Lett 2011 Mar;36(6):951-3

College of Opticelectric Science and Engineering, National University of Defense Technology, Changsha, China.

Coherent beam combination of a 1.08 kW fiber amplifier array has been demonstrated for the first time, to our knowledge. In the experiment, nine fiber amplifiers are tiled into a 3×3 array, and the output power of each amplifier is approximately 120 W. A single frequency dithering algorithm is used to compensate the phase noises between the elements, which runs on a signal processor based on field programmable gate array for phase control on the fiber amplifiers. When the phase control system goes into closed loop, the fringe contrast of the far-field intensity pattern is improved to more than 85%, and the residual phase error is less than λ/15.
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http://dx.doi.org/10.1364/OL.36.000951DOI Listing
March 2011

Evaluating the impact of hepatitis C virus (HCV) on highly active antiretroviral therapy-mediated immune responses in HCV/HIV-coinfected women: role of HCV on expression of primed/memory T cells.

J Infect Dis 2006 May 17;193(9):1202-10. Epub 2006 Mar 17.

Rush University Medical Center, Chicago, Illinois 60612, USA.

Objective: To evaluate the impact of hepatitis C virus (HCV) on the immune system before receipt of highly active antiretroviral therapy (HAART) and on immune recovery after receipt of HAART among human immunodeficiency virus (HIV)/HCV-coinfected women enrolled in the Women's Interagency HIV Study.

Methods: The study included 294 HIV-infected women who initiated HAART and attended 2 follow-up visits. The women were grouped on the basis of positive HCV antibody and HCV RNA tests. There were 148 women who were HCV antibody negative, 34 who were HCV antibody positive but RNA negative, and 112 who were HCV antibody and RNA positive. Immune recovery was measured by flow-cytometric assessment for markers of activation and maturation on CD4+ and CD8+ T cells. Data analysis used repeated measures of variance.Results. HIV/HCV coinfection is associated with an increased number of CD4+ and CD8+ primed/memory T cells. HIV/HCV coinfection, however, did not affect any further decreases in CD4+ or CD4+ and CD8+ naive/memory T cell counts or enhanced T cell activation. HIV/HCV coinfection also did not affect HAART responses in the CD4+ and CD8+ T cell compartment.

Conclusions: HCV does not affect immune responses to HAART in HIV/HCV-coinfected individuals but is associated with an expansion of CD4+ and CD8+ memory T cell subsets. Functional impairment in the CD4+ and CD8+ T cell compartments still needs to be assessed in coinfected patients.
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http://dx.doi.org/10.1086/500843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3126663PMC
May 2006

Presence of hepatitis C virus (HCV) RNA in the genital tracts of HCV/HIV-1-coinfected women.

J Infect Dis 2005 Nov 29;192(9):1557-65. Epub 2005 Sep 29.

Maternal-Child and Adolescent Center for Infectious Diseases and Virology, University of Southern California, Los Angeles 90033, and Mayo Clinic, Scottsdale, USA.

Background: Hepatitis C virus (HCV)-infected women--in particular, those coinfected with human immunodeficiency virus type 1 (HIV-1)--can transmit infection to their children and sex partners.

Methods: The present study was conducted to analyze the presence of HCV RNA in cervicovaginal lavage (CVL) fluid from 71 women (58 HCV/HIV-1-coinfected women and 13 HCV-infected, HIV-1-uninfected women) enrolled in the Women's Interagency HIV Study.

Results: HCV RNA was detected (by a commercial polymerase chain reaction assay) in CVL fluid from 18 (29%) of the HIV-1-infected women and from none of the HIV-1-uninfected women (P<.05). Multivariate analysis revealed that risk factors for the presence of HCV RNA in CVL fluid were HCV viremia (odds ratio [OR], 16.81; P=.02) and HIV-1 RNA in CVL fluid (OR, 19.87; P=.02). This observation suggests local interactions between HIV-1 and HCV in the genital tract compartment. There was no correlation between HCV RNA in CVL fluid and CD4, CD8, or CD3 cell counts, HIV-1 RNA viremia, the number of leukocytes in CVL fluid, or HIV-1 therapy. Furthermore, in 3 of 5 analyzed patients who had a detectable CVL HCV RNA load, we found viral variants differing in the 5' untranslated region that were present neither in plasma nor in peripheral-blood mononuclear cells.

Conclusions: Our observations point to the importance of the genital tract compartment, in which local HCV replication could be facilitated by local HIV-1 replication.
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http://dx.doi.org/10.1086/491742DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164119PMC
November 2005

HCV viremia is associated with drug use in young HIV-1 and HCV coinfected pregnant and non-pregnant women.

Addiction 2005 May;100(5):626-35

Maternal, Child and Adolescent Center for Infectious Diseases and Virology, Los Angeles County and University of Southern California Medical Center, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA.

Aims: Vertical transmission of HCV is increased among HIV-1/HCV coinfected women and is related to HCV viral load. In this study we assessed clinical and demographic factors associated with HCV viremia in a cohort of young pregnant and non-pregnant mothers coinfected with HIV-1.

Design: A cross-sectional clinic-based study nested within a prospective cohort study.

Methods: From 1988 to 2000, HIV-1 + pregnant and non-pregnant women with children followed in a large maternal, child and adolescent HIV-1 clinic were evaluated for HCV infection using EIA 3.0. HCV RNA levels were determined for HCV antibody + women using polymerase chain reaction. Demographic and clinical characteristics between HCV-RNA(+) and HCV-RNA(-) women and between pregnant and non-pregnant HIV-1/HCV coinfected women were compared using univariate and multivariate analyses.

Findings: Among 359 HIV-1(+) women, 84 (23%) were HCV-ab + and 49/84 (58%) had detectable HCV-RNA in plasma. Median age was 31. CD4 counts, HIV-1 RNA levels and demographic characteristics were similar for viremic and non-viremic women and pregnant and non-pregnant women. However, viremic women were more likely to report a history of (88% versus 43%; P < 0.001) or active injection drug use (AIDU) (83% versus 29%; P < 0.001). Logistic regression analysis showed that HCV viremia was associated significantly with AIDU (adjusted OR: 15.17; 95% CI: 3.56, 64.56) after adjusting for age, race, number of sexual partners, pregnancy status, CD4 counts and HIV-1 viral load.

Conclusion: In this cohort of young HIV-1 and HCV coinfected women, HCV viremia was associated strongly with active injection drug use, perhaps due to reinfection or reactivation of HCV. Thus, careful evaluation for HCV infection and counseling related to drug use may be necessary.
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http://dx.doi.org/10.1111/j.1360-0443.2005.01054.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3118993PMC
May 2005

Reduced type 1 and type 2 cytokines in antiviral memory T helper function among women coinfected with HIV and HCV.

J Clin Immunol 2005 Mar;25(2):134-41

Maternal, Child and Adolescent Center for Infectious Diseases and Virology, Keck School of Medicine, University of Southern California, Los Angeles, CA 99033, USA.

Bias in cytokine responses has been proposed as a contributing mechanism to pathogenesis in persistent HIV or hepatitis C virus (HCV) infections. We investigated whether coinfection with HCV modifies the profile of antigen-specific cytokine secretion in women persistently infected with HIV compared to women with single HIV or HCV infection. The T helper response to HIV, HCV and cytomegalovirus (CMV) as a positive viral control was dominated by type 1 cytokines (interleukin- [IL] 2, interferon- [IFN] gamma and tumor necrosis factor- [TNF] alpha), with IFN-gamma as the most abundantly secreted. IL-4, IL-5 and IL-10 were low in healthy controls and patients. Robust CMV-specific responses contrasted with curtailed HCV-specific responses in HCV-infected women. The overall anti-viral profile was dominated by Th1 cytokines even in coinfected women but both type 1 and type 2 responses were reduced in HIV-infected women and more extensively in women with HCV/HIV coinfection.
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http://dx.doi.org/10.1007/s10875-005-2819-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127261PMC
March 2005

Incidence and survival of mucinous adenocarcinoma of the colorectum: a population-based study from an Asian country.

Dis Colon Rectum 2004 Jan 14;47(1):78-85. Epub 2004 Jan 14.

Department of Community, Occupational and Family Medicine, National University of Singapore, Singapore.

Purpose: Previous studies have shown conflicting results on the prognosis of mucinous adenocarcinoma of the colorectum. This could be because of heavy bias on patient selection. Furthermore, little data are available from Asian populations. This study was designed to examine incident and prognostic characteristics of mucinous adenocarcinoma of the colorectum based on data obtained from a population-based, Asian, cancer registry.

Methods: A total of 627 of 15,762 were mucinous adenocarcinoma cases from invasive colorectal cancer patients registered in the Singapore Registry from 1968 to 1997. Age-standardized incidence rate was used to describe the incident pattern of mucinous adenocarcinoma of colon and rectum during a period of time. Survival of patients with mucinous adenocarcinoma or ordinary adenocarcinoma was compared using relative survival and proportional hazards model.

Results: Age-standardized incidence rate of mucinous adenocarcinoma of the colon and rectum were almost unchanged in males, rising slightly in females during the study periods from 1968 to 1972 to 1993 to 1997. The proportion of mucinous adenocarcinoma cases was similar among genders and calendar-year periods but was higher in younger age groups, Malays and Indians, in advanced stages of the disease, and proximal colon. Five-year relative survival rate of patients with mucinous adenocarcinoma were similar in the colon but were lower in the rectum.

Conclusions: Colorectal mucinous adenocarcinoma as a different etiologic entity from other histologic types of colorectal cancer was suggested. Possibly greater aggressiveness of mucinous adenocarcinoma occurring in the rectum requires confirmation but suggests that mucin is important in the pathogenesis of mucinous adenocarcinoma.
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http://dx.doi.org/10.1007/s10350-003-0014-9DOI Listing
January 2004
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