| 21. |
- Wang, Gang, et al.
(författare)
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Aggregation control in natural brush-printed conjugated polymer films and implications for enhancing charge transport
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 114:47, s. E10066-E10073
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Tidskriftsartikel (refereegranskat)abstract
- Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7x/3.9x, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R-2 (R-adj(2)) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization.
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| 22. |
- Wang, Gang, et al.
(författare)
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Mixed-flow design for microfluidic printing of two-component polymer semiconductor systems
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 117:30, s. 17551-17557
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Tidskriftsartikel (refereegranskat)abstract
- The rational creation of two-component conjugated polymer sys-tems with high levels of phase purity in each component is challenging but crucial for realizing printed soft-matter electronics. Here, we report a mixed-flow microfluidic printing (MFMP) approach for two-component pi-polymer systems that significantly elevates phase purity in bulk-heterojunction solar cells and thin-film transistors. MFMP integrates laminar and extensional flows using a specially microstructured shear blade, designed with fluid flow simulation tools to tune the flow patterns and induce shear, stretch, and pushout effects. This optimizes polymer conformation and semi-conducting blend order as assessed by atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing incidence wide-angle X-ray scattering (GIWAXS), resonant soft X-ray scattering (R-SoXS), photovoltaic response, and field effect mobility. For printed all-polymer (poly[(5,6-difluoro-2-octyl-2H-benzotriazole-4,7-diyl)-2,5-thiophenediyl[4,8-bis[5-(2-hexyldecyl)-2-thienyl]benzo[1,2-b:4,5-b ]dithiophene-2,6-diyl]-2,5-thiophenediyl]) [J51]:(poly{[N,N -bis(2-octyldodecyl) naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5 -(2,2 -bithio-phene)}) [N2200]) solar cells, this approach enhances short-circuit currents and fill factors, with power conversion efficiency increasing from 5.20% for conventional blade coating to 7.80% for MFMP. Moreover, the performance of mixed polymer ambipolar [poly(3-hexylthiophene-2,5-diyl) (P3HT):N2200] and semiconducting:insulat-ing polymer unipolar (N2200:polystyrene) transistors is similarly enhanced, underscoring versatility for two-component pi-polymer systems. Mixed-flow designs offer modalities for achieving high-performance organic optoelectronics via innovative printing methodologies.
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| 23. |
- Wang, Huijiao, et al.
(författare)
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Oxidation of emerging biocides and antibiotics in wastewater by ozonation and the electro-peroxone process
- 2019
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 235, s. 575-585
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the abatement of a number of antimicrobials frequently detected in municipal wastewater by conventional ozonation and a recently developed ozone-based advanced oxidation process, the electro-peroxone (E-peroxone) process. A synthetic water and a real secondary wastewater effluent were spiked with fourteen antimicrobials, including antibiotics and biocides, and then treated by the two processes. The results show that most of the antibiotics investigated (e.g., ofloxacin, trimethoprim, norfloxacin, and ciprofloxacin) readily react with ozone (O3) and could therefore be efficiently eliminated from the water matrices by direct O3 oxidation during both processes. In contrast, most of the biocides tested in this study (e.g., clotrimazole, pentamidine, bixafen, propiconazole, and fluconazole) were only moderately reactive, or non-reactive, with O3. Therefore, these biocides were removed at considerably lower rate than the antibiotics during the two ozone-based processes, with hydroxyl radical (OH) oxidation playing an important role in their abatement mechanisms. When compared with conventional ozonation, the E-peroxone process is defined by the in situ electrogeneration of hydrogen peroxide, which considerably enhances the transformation of O3 to OH. As a result, the E-peroxone process significantly accelerated the abatement of biocides and required a considerably shorter treatment time to eliminate all of the tested compounds from the water matrices than conventional ozonation. In addition, the E-peroxone process enhanced the contributions of OH fractions to the abatement of moderately ozone reactive benzotriazoles. These results demonstrate that the E-peroxone process holds promise as an effective tertiary treatment option for enhancing the abatement of ozone-resistant antimicrobials in wastewater.
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| 24. |
- Wang, Lu, et al.
(författare)
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Design of Chipless RFID Tag by Using Miniaturized Open-Loop Resonators
- 2018
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:2, s. 618-626
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, an open-loop resonator with fragment-loading structure is used for the first time in the design of radar cross section-based chipless radio-frequency identification (RFID) tag. By optimizing the distribution of fragment patches in an open loop, a microstrip open-loop resonator can be miniaturized so that the data capacity of the chipless RFID tag designed using such a miniaturized loop resonator can be significantly increased. Moreover, the resonant frequency of the fragment-loaded resonator can be adjusted conveniently by removing or disconnecting some fragment patches, which provides great flexibility for data encoding of the chipless RFID tag. The proposed chipless RFID tag with miniaturized open-loop resonators is designed and tested and can acquire 3.56 bits per resonator and a coding density of approximately 745.1bits/λg 2. Several experimental results validate the proposed design as well as its implementation in a realistic environment.
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| 25. |
- Wang, Lu, et al.
(författare)
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High-performance tight coupling microstrip directional coupler with fragment-type compensated structure
- 2017
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Ingår i: IET Microwaves, Antennas & Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 11:7, s. 1057-1063
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a design scheme for high-performance tight coupling microstrip coupler is proposed by adding a fragment-type compensated structure between two loosely coupled lines. Owing to its flexibility and adaptability, the fragment-type compensated structure can not only provide a quarter-wavelength phase shift for coupling enhancement, but also compensate the difference in the phase velocities of the even- and odd-modes for high directivity. Design of the fragment-type compensated structure can be implemented by multi-objective optimisation searching with several design objectives characterising tight coupling couplers. A high-efficiency optimisation searching strategy by using two-dimensional median filtering operator is employed to improve the efficiency of multi-objective optimisation. For demonstration, a high-performance 3-dB tight coupling directional coupler operating at 2 GHz is designed. The measurement data demonstrates a maximum directivity of 47 dB, above 25 dB directivity in a 21.5% bandwidth, a maximum variation of 0.3 dB in the coupling level and a maximum power division ratio of 0.6 dB, which indicate the overall performance better than the previously reported 3-dB couplers. In addition, a simplified theoretical analysis of the proposed coupler and full-wave simulated results are provided for better understanding of the fragment-type compensated structure.
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| 26. |
- Wang, Suhao, et al.
(författare)
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A Chemically Doped Naphthalenediimide-Bithiazole Polymer for n-Type Organic Thermoelectrics
- 2018
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:31
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a novel naphthalenediimide (NDI)-bithiazole (Tz2)-based polymer [P(NDI2OD-Tz2)] is reported, and structural, thin-film morphological, as well as charge transport and thermoelectric properties are compared to the parent and widely investigated NDI-bithiophene (T2) polymer [P(NDI2OD-T2)]. Since the steric repulsions in Tz2 are far lower than in T2, P(NDI2OD-Tz2) exhibits a more planar and rigid backbone, enhancing p-p chain stacking and intermolecular interactions. In addition, the electron-deficient nature of Tz2 enhances the polymer electron affinity, thus reducing the polymer donor-acceptor character. When n-doped with amines, P(NDI2OD-Tz2) achieves electrical conductivity (approximate to 0.1 S cm(-1)) and a power factor (1.5 mu W m(-1) K-2) far greater than those of P(NDI2OD-T2) (0.003 S cm(-1) and 0.012 mu W m(-1) K-2, respectively). These results demonstrate that planarized NDI-based polymers with reduced donor-acceptor character can achieve substantial electrical conductivity and thermoelectric response.
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| 27. |
- Wang, Sheng-Jun, 1981-, et al.
(författare)
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Influence of synaptic interaction on firing synchronization and spike death in excitatory neuronal networks
- 2008
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - New York : American Physical Society through the American Institute of Physics. - 1063-651X .- 1095-3787. ; 78:6, s. 061906-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the influence of efficacy of synaptic interaction on firing synchronization in excitatoryneuronal networks. We find spike death phenomena: namely, the state of neurons transits from the limit cycleto a fixed point or transient state. The phenomena occur under the perturbation of an excitatory synapticinteraction, which has a high efficacy. We show that the decrease of synaptic current results in spike deaththrough depressing the feedback of the sodium ionic current. In the networks with the spike death property thedegree of synchronization is lower and insensitive to the heterogeneity of neurons. The mechanism of theinfluence is that the transition of the neuron state disrupts the adjustment of the rhythm of the neuronsoscillation and prevents a further increase of the firing synchronization.
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| 28. |
- Wang, Suhao, et al.
(författare)
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Sequential Doping of Ladder-Type Conjugated Polymers for Thermally Stable n-Type Organic Conductors
- 2020
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 12:47, s. 53003-53011
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Tidskriftsartikel (refereegranskat)abstract
- Doping of organic semiconductors is a powerful tool to optimize the performance of various organic (opto)electronic and bioelectronic devices. Despite recent advances, the low thermal stability of the electronic properties of doped polymers still represents a significant obstacle to implementing these materials into practical applications. Hence, the development of conducting doped polymers with excellent long-term stability at elevated temperatures is highly desirable. Here, we report on the sequential doping of the ladder-type polymer poly(benzimidazobenzophenanthroline) (BBL) with a benzimidazole-based dopant (i.e., N-DMBI). By combining electrical, UV-vis/infrared, X-ray diffraction, and electron paramagnetic resonance measurements, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, and microstructure of the sequentially doped polymer films as a function of the thermal annealing temperature. Importantly, we observed that the electrical conductivity of N-DMBI-doped BBL remains unchanged even after 20 h of heating at 190 °C. This finding is remarkable and of particular interest for organic thermoelectrics.
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| 29. |
- Wang, Xinchen, et al.
(författare)
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Design of High-Data-Density Chipless RFID Tag Embedded in QR Code
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:3, s. 2189-2198
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Tidskriftsartikel (refereegranskat)abstract
- A design scheme for embedding a chipless radio frequency identification (RFID) tag in a quick response (QR) code is proposed and demonstrated. By searching for QR modules that can be metalized to form a loop resonator in the edge area and to load the loop in the central area, the chipless RFID tag with an optimized loaded-loop resonator can be designed in the QR code. A specific loop genetic operator is proposed for optimization searching. The optimized loaded-loop resonator has a sharp dominant resonant peak at frequency as low as possible and a harmonic resonant peak at frequency as high as possible, which provides large space for data encoding of chipless RFID. By removing or demetalizing the metalized loading modules, the resonant frequency can be tuned conveniently for frequency shift keying (FSK) coding. For demonstration, the chipless RFID tag embedded in the QR code is designed and tested. It is shown that the RFID tag allows at least nine distinct resonant frequencies for simple FSK coding, which indicates a coding capacity of 3.17 bits and a normalization coding density of approximately 501.78 bits/ $\lambda _{\mathrm {g}}^{2}$ /GHz for the chipless RFID tag embedded in the QR code.
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| 30. |
- Xiao, Chao, et al.
(författare)
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RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer
- 2018
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Ingår i: Cancer Science. - : Blackwell Publishing. - 1347-9032 .- 1349-7006. ; 109:4, s. 1075-1087
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Tidskriftsartikel (refereegranskat)abstract
- Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but the radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. This study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both two cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6-knockdown cells. Besides, transfection with RBBP6 shRNA improved levels of G2-M phase arrest which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, tumor growth rate of nude mice in RBBP6-knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.
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