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Donald L Sparks - One of the best experts on this subject based on the ideXlab platform.
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residence time and Ph effects on the bonding configuration of orthoPhosPhate Surface comPlexes at the goethite water interface as examined by extended x ray absorPtion fine structure exafs sPectroscoPy
Journal of Colloid and Interface Science, 2015Co-Authors: Dalton Belchior Abdala, Paul Northrup, Flavio Cesar Vicentin, Donald L SparksAbstract:Abstract Identifying the mechanisms by which P is bound to soils and soil constituents is ultimately imPortant as they Provide information on the stability of bound sPecies and their reactivity in the environment. EXAFS studies were carried out to Provide information on how the local chemical environment of sorbed P changes as an effect of PH and time. Goethite was reacted with orthoPhosPhate at a P concentration of 0.8 mmol L −1 P at PH 3.0, 4.5 and 6.0. The residence time effect on the mechanisms of P sorPtion on goethite was also evaluated for two different reaction times, 5 and 18 days, on goethite susPensions reacted at PH 4.5. The objective of this study was to understand how P sorPtion mechanisms change over a wide PH range when subjected to P concentrations above the P saturation ratio of goethite. PhosPhorus K-edge EXAFS sPectra were collected at 2150 eV in fluorescence mode and the structural Parameters were obtained through the fits of sorPtion data using Artemis. The monodentate Surface comPlex was shown to be the Predominant mechanism by which P sorbs at the goethite Surface under the exPerimental conditions. The lack of a discrete Fe–P shell and the Presence of highly disordered structures, Particularly, at R -sPace ⩾3.5 suggested the formation of P Surface PreciPitates at the goethite/water interface.
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Surface loading effects on orthoPhosPhate Surface comPlexation at the goethite water interface as examined by extended x ray absorPtion fine structure exafs sPectroscoPy
Journal of Colloid and Interface Science, 2015Co-Authors: Dalton Belchior Abdala, Paul Northrup, Yuji Arai, Donald L SparksAbstract:Abstract To investigate the effect of P Surface loading on the structure of Surface comPlexes formed at the goethite/water interface, goethite was reacted with orthoPhosPhate at P concentrations of 0.1, 0.2, and 0.8 mmol L −1 at PH 4.5 for 5 days. The P concentrations were chosen to ensure that P loadings at the Surface would allow one to follow the transition between adsorPtion and Surface PreciPitation. Extended X-ray AbsorPtion Fine Structure (EXAFS) sPectra were collected in fluorescence mode at the P K-edge at 2150 eV. The structural Parameters were obtained through the fits of the sorPtion data to single and multiPle scattering Paths using Artemis. EXAFS analysis revealed a continuum among the different Surface comPlexes, with bidentate mononuclear ( 2 E), bidentate binuclear ( 2 C) and monodentate mononuclear ( 1 V) Surface comPlexes forming at the goethite/water interface under the studied conditions. The distances for P–O (1.51–1.53 A) and P–Fe (3.2–3.3 A for bidentate binuclear and around 3.6 A for mononuclear Surface comPlexes) shells observed in our study were consistent with distances obtained via other sPectroscoPic techniques. The shortest P–Fe distance of 2.83–2.87 A was indicative of a bidentate mononuclear bonding configuration. The coexistence of different Surface comPlexes or the Predominance of one sorPtion mechanism over others was directly related to Surface loading.
Xingrong Zeng - One of the best experts on this subject based on the ideXlab platform.
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dual functional suPerhydroPhobic textiles with asymmetric roll down Pinned states for water droPlet transPortation and oil water seParation
ACS Applied Materials & Interfaces, 2018Co-Authors: Xuejun Lai, Lin Zhang, Xiaofeng Liao, Jing Wang, Zhonghua Chen, Xingrong ZengAbstract:SuPerhydroPhobic Surfaces with tunable adhesion from lotus-leaf to rose-Petal states have generated much attention for their Potential aPPlications in self-cleaning, anti-icing, oil–water seParation, microdroPlet transPortation, and microfluidic devices. Herein we rePort a facile magnetic-field-maniPulation strategy to fabricate dual-functional suPerhydroPhobic textiles with asymmetric roll-down/Pinned states on the two Surfaces of the textile simultaneously. UPon exPosure to a static magnetic field, fluoroalkylsilane-modified iron oxide (F-Fe3O4) nanoParticles in Polydimethylsiloxane (PDMS) moved along the magnetic field to construct discrePant hierarchical structures and roughnesses on the two sides of the textile. The Positive Surface (closer to the magnet, or P-Surface) showed a water contact angle uP to 165°, and the oPPosite Surface (or O-Surface) had a water contact angle of 152.5°. The P-Surface where water droPlets easily slid off with a sliding angle of 7.5° aPPeared in the “roll-down” state as ...
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Dual-Functional SuPerhydroPhobic Textiles with Asymmetric Roll-Down/Pinned States for Water DroPlet TransPortation and Oil–Water SeParation
2018Co-Authors: Xuejun Lai, Lin Zhang, Xiaofeng Liao, Jing Wang, Zhonghua Chen, Xingrong ZengAbstract:SuPerhydroPhobic Surfaces with tunable adhesion from lotus-leaf to rose-Petal states have generated much attention for their Potential aPPlications in self-cleaning, anti-icing, oil–water seParation, microdroPlet transPortation, and microfluidic devices. Herein we rePort a facile magnetic-field-maniPulation strategy to fabricate dual-functional suPerhydroPhobic textiles with asymmetric roll-down/Pinned states on the two Surfaces of the textile simultaneously. UPon exPosure to a static magnetic field, fluoroalkylsilane-modified iron oxide (F-Fe3O4) nanoParticles in Polydimethylsiloxane (PDMS) moved along the magnetic field to construct discrePant hierarchical structures and roughnesses on the two sides of the textile. The Positive Surface (closer to the magnet, or P-Surface) showed a water contact angle uP to 165°, and the oPPosite Surface (or O-Surface) had a water contact angle of 152.5°. The P-Surface where water droPlets easily slid off with a sliding angle of 7.5° aPPeared in the “roll-down” state as Cassie mode, while the O-Surface was in the “Pinned” state as Wenzel mode, where water droPlets firmly adhered even at vertical (90°) and inverted (180°) angles. The Surface morPhology and wetting mode were adjustable by varying the ratios of F-Fe3O4 nanoParticles and PDMS. By taking advantage of the asymmetric adhesion behaviors, the as-fabricated suPerhydroPhobic textile was successfully aPPlied in no-loss microdroPlet transPortation and oil–water seParation. Our method is simPle and cost-effective. The fabricated textile has the characteristics of suPerhydroPhobicity, magnetic resPonsiveness, excellent chemical stability, adjustable Surface morPhology, and controllable adhesion. Our findings conceivably stand out as a new tool to fabricate functional suPerhydroPhobic materials with asymmetric Surface ProPerties for various Potential aPPlications
Dalton Belchior Abdala - One of the best experts on this subject based on the ideXlab platform.
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residence time and Ph effects on the bonding configuration of orthoPhosPhate Surface comPlexes at the goethite water interface as examined by extended x ray absorPtion fine structure exafs sPectroscoPy
Journal of Colloid and Interface Science, 2015Co-Authors: Dalton Belchior Abdala, Paul Northrup, Flavio Cesar Vicentin, Donald L SparksAbstract:Abstract Identifying the mechanisms by which P is bound to soils and soil constituents is ultimately imPortant as they Provide information on the stability of bound sPecies and their reactivity in the environment. EXAFS studies were carried out to Provide information on how the local chemical environment of sorbed P changes as an effect of PH and time. Goethite was reacted with orthoPhosPhate at a P concentration of 0.8 mmol L −1 P at PH 3.0, 4.5 and 6.0. The residence time effect on the mechanisms of P sorPtion on goethite was also evaluated for two different reaction times, 5 and 18 days, on goethite susPensions reacted at PH 4.5. The objective of this study was to understand how P sorPtion mechanisms change over a wide PH range when subjected to P concentrations above the P saturation ratio of goethite. PhosPhorus K-edge EXAFS sPectra were collected at 2150 eV in fluorescence mode and the structural Parameters were obtained through the fits of sorPtion data using Artemis. The monodentate Surface comPlex was shown to be the Predominant mechanism by which P sorbs at the goethite Surface under the exPerimental conditions. The lack of a discrete Fe–P shell and the Presence of highly disordered structures, Particularly, at R -sPace ⩾3.5 suggested the formation of P Surface PreciPitates at the goethite/water interface.
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Surface loading effects on orthoPhosPhate Surface comPlexation at the goethite water interface as examined by extended x ray absorPtion fine structure exafs sPectroscoPy
Journal of Colloid and Interface Science, 2015Co-Authors: Dalton Belchior Abdala, Paul Northrup, Yuji Arai, Donald L SparksAbstract:Abstract To investigate the effect of P Surface loading on the structure of Surface comPlexes formed at the goethite/water interface, goethite was reacted with orthoPhosPhate at P concentrations of 0.1, 0.2, and 0.8 mmol L −1 at PH 4.5 for 5 days. The P concentrations were chosen to ensure that P loadings at the Surface would allow one to follow the transition between adsorPtion and Surface PreciPitation. Extended X-ray AbsorPtion Fine Structure (EXAFS) sPectra were collected in fluorescence mode at the P K-edge at 2150 eV. The structural Parameters were obtained through the fits of the sorPtion data to single and multiPle scattering Paths using Artemis. EXAFS analysis revealed a continuum among the different Surface comPlexes, with bidentate mononuclear ( 2 E), bidentate binuclear ( 2 C) and monodentate mononuclear ( 1 V) Surface comPlexes forming at the goethite/water interface under the studied conditions. The distances for P–O (1.51–1.53 A) and P–Fe (3.2–3.3 A for bidentate binuclear and around 3.6 A for mononuclear Surface comPlexes) shells observed in our study were consistent with distances obtained via other sPectroscoPic techniques. The shortest P–Fe distance of 2.83–2.87 A was indicative of a bidentate mononuclear bonding configuration. The coexistence of different Surface comPlexes or the Predominance of one sorPtion mechanism over others was directly related to Surface loading.
Javad Kadkhodapour - One of the best experts on this subject based on the ideXlab platform.
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Additive manufacturing and mechanical characterization of graded Porosity scaffolds designed based on triPly Periodic minimal Surface architectures
Journal of the Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Maziar Afshar, A. Pourkamali Anaraki, H Montazerian, Javad KadkhodapourAbstract:Since the advent of additive manufacturing techniques, triPly Periodic minimal Surfaces have emerged as a novel tool for designing Porous scaffolds. Whereas scaffolds are exPected to Provide multifunctional Performance, sPatially changing Pore Patterns have been a Promising aPProach to integrate mechanical characteristics of different architectures into a unique scaffold. Smooth morPhological variations are also frequently seen in nature Particularly in bone and cartilage structures and can be insPiring for designing of artificial tissues. In this study, we carried out exPerimental and numerical Procedures to uncover the mechanical ProPerties and deformation mechanisms of linearly graded Porosity scaffolds for two different mathematically defined Pore structures. Among TPMS-based scaffolds, P and D Surfaces were subjected to gradient modeling to exPlore the mechanical resPonses for stretching and bending dominated deformations, resPectively. Moreover, the results were comPared to their corresPonding uniform Porosity structures. Mechanical ProPerties were found to be by far greater for the stretching dominated structure (P-Surface). For bending dominated architecture (D-Surface), although there was no global fracture for uniform structures, graded structure showed a brittle fracture at 0.08 strain. A layer by layer deformation mechanism for stretching dominated structure was observed. For bending dominated scaffolds, deformation was accomPanied by develoPment of 45° shearing bands. Finite element simulations were also Performed and the results showed a good agreement with the exPerimental observations.
Zhao Yiran - One of the best experts on this subject based on the ideXlab platform.
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Advanced Bifacial Solar Cell with Poly-Si Passivating Contacts
2018Co-Authors: Zhao YiranAbstract:As a new face of PV industry, bifacial technology offers the utmost utilization of reflected light while efforts are still required to further imProve its cell efficiency. The objective of this thesis Project is to fabricate bifacial solar cell with Poly-Si Passivating contacts only underneath metal grids. An advanced bifacial architecture is Presented combining carrier-selective n/P+ doPed Poly-Si Passivating contacts to quench recombination at c-Si/metal interface, and lightly doPed n/P tyPe c-Si Surface to ensure high oPtical transParency on both sides. LPCVD based doPed Poly-Si works together with wet-chemically grown ultrathin oxide, Providing both field-effect and chemical Passivation for metal contacts. By investigation into Poly-Si thickness and thermal budget, symmetric test samPles show a good Passivation of 5.4fA/cm2 J0 for n doPed Poly-Si and 10.9fA/cm2 J0 for P doPed Poly-Si.An oPtimal n+ c-Si Surface Passivation of 14.5 fA/cm2 J0 is achieved with PECVD dePosited a-Si:H/SiNX stack on textured wafers. For P+ c-Si Surface Passivation, the influence of thermal ALD Al2O3 film thickness and Forming Gas Annealing on Al2O3/SiNX stack is studied. Also an oPtimal P+ Surface with 123 Ω/sq sheet resistance is formed by boron ion imPlantation aPProach, which Provides sPace to Play with the trade-off between Surface Passivation and lateral carrier transPort for emitter and front/back Surface field. APPlying oPtimized results, bifacial solar cell fabrication enables only one-time high temPerature annealing for both highly doPed Poly-Si and lightly doPed c-Si activation. Following such flowchart, n/P bulk rear/front junction test PeRFeCT cells were fabricated, stressing the imPortance of FSF Passivation on solar cell VOC Performance.A good Passivated bifacial cell Precursor is also PrePared with iVOC of 714mV while BHF, Poly-etch and TMAH develoPer in bifacial cell fabrication is Proved to over-etch Poly-Si Passivaitng material, resulting in a Poor Performance. For further imProvement with smooth Processing and delicate control of etching stePs, a good Performed bifacial solar cell with Poly-Si Passivaing contacts is exPected to be fabricated.Sustainable Energy Technolog
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Advanced Bifacial Solar Cell with Poly-Si Passivating Contacts
2018Co-Authors: Zhao YiranAbstract:As a new face of PV industry, bifacial technology offers the utmost utilization of reflected light while efforts are still required to further imProve its cell efficiency. The objective of this thesis Project is to fabricate bifacial solar cell with Poly-Si Passivating contacts only underneath metal grids. An advanced bifacial architecture is Presented combining carrier-selective n/P+ doPed Poly-Si Passivating contacts to quench recombination at c-Si/metal interface, and lightly doPed n/P tyPe c-Si Surface to ensure high oPtical transParency on both sides. LPCVD based doPed Poly-Si works together with wet-chemically grown ultrathin oxide, Providing both field-effect and chemical Passivation for metal contacts. By investigation into Poly-Si thickness and thermal budget, symmetric test samPles show a good Passivation of 5.4fA/cm2 J0 for n doPed Poly-Si and 10.9fA/cm2 J0 for P doPed Poly-Si.An oPtimal n+ c-Si Surface Passivation of 14.5 fA/cm2 J0 is achieved with PECVD dePosited a-Si:H/SiNX stack on textured wafers. For P+ c-Si Surface Passivation, the influence of thermal ALD Al2O3 film thickness and Forming Gas Annealing on Al2O3/SiNX stack is studied. Also an oPtimal P+ Surface with 123 Ω/sq sheet resistance is formed by boron ion imPlantation aPProach, which Provides sPace to Play with the trade-off between Surface Passivation and lateral carrier transPort for emitter and front/back Surface field. APPlying oPtimized results, bifacial solar cell fabrication enables only one-time high temPerature annealing for both highly doPed Poly-Si and lightly doPed c-Si activation. Following such flowchart, n/P bulk rear/front junction test PeRFeCT cells were fabricated, stressing the imPortance of FSF Passivation on solar cell VOC Performance.A good Passivated bifacial cell Precursor is also PrePared with iVOC of 714mV while BHF, Poly-etch and TMAH develoPer in bifacial cell fabrication is Proved to over-etch Poly-Si Passivaitng material, resulting in a Poor Performance. For further imProvement with smooth Processing and delicate control of etching stePs, a good Performed bifacial solar cell with Poly-Si Passivaing contacts is exPected to be fabricated.Electrical Engineering | Sustainable Energy Technolog
