101 research outputs found
Emerging efficient charge-transport landscape based on short-range order in conjugated polymers
No full textThe booming of classic semicrystalline polymers has led to the assumption and thus design guidelines that long-range order is a prerequisite to endow conjugated polymers with high charge carrier mobility. Consequently, tremendous research effort has been devoted to increasing the crystallinity of conjugated polymers, as a principal strategy to improve the solid-state long-range charge-transport properties. Indeed, noticeable progress in the polymer performance has been witnessed. However, only a limited level of crystallinity can be achieved due to the inherently disordered nature of the polymer chains, resulting in the bottlenecks of the charge carrier mobility of conjugated polymers. Encouragingly, the recent reports of substantially disordered, high-performance conjugated polymers have opened a new route for achieving efficient charge transport, and lead to new waves of progress in the field of organic electronics. The universal observation of short-range order (in the form of aggregation) in the emerging class of poorly ordered conjugated polymers seems to suggest that local order is sufficient for efficient charge transport, and that extended long-range crystallinity is not essential. This review discusses the molecular origin of the high mobilities observed in the state-of-the-art low-crystalline conjugated polymers, especially highlighting the crucial role of short-range order
Control over microstructure evolution and device performance in solution processable organic field-effect transistors
No full textDie Arbeit beschäftigt sich mit der Kontrolle von Selbstorganisation und Mikrostruktur von organischen Halbleitern und deren Einsatz in OFETs. In Kapiteln 3, 4 und 5 eine neue Lösungsmittel-basierte Verabeitungsmethode, genannt als Lösungsmitteldampfdiffusion, ist konzipiert, um die Selbstorganisation von Halbleitermolekülen auf der Oberfläche zu steuern. Diese Methode als wirkungsvolles Werkzeug erlaubt eine genaue Kontrolle über die Mikrostruktur, wie in Kapitel 3 am Beispiel einer D-A Dyad bestehend aus Hexa-peri-hexabenzocoronene (HBC) als Donor und Perylene Diimide (PDI) als Akzeptor beweisen. Die Kombination aus Oberflächenmodifikation und Lösungsmitteldampf kann die Entnetzungseffekte ausgleichen, so dass die gewüschte Mikrostruktur und molekulare Organisation auf der Oberfläche erreicht werden kann. In Kapiteln 4 und 5 wurde diese Methode eingesetzt, um die Selbstorganisation von Dithieno[2, 3-d;2’, 3’-d’] benzo[1,2-b;4,5-b’]dithiophene (DTBDT) und Cyclopentadithiophene -benzothiadiazole copolymer (CDT-BTZ) Copolymer zu steuern. Die Ergebnisse könnten weitere Studien stimulieren und werfen Licht aus andere leistungsfaähige konjugierte Polymere. rnIn Kapiteln 6 und 7 Monolagen und deren anschlieβende Mikrostruktur von zwei konjugierten Polymeren, Poly (2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) PBTTT und Poly{[N,N ′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis (dicarboximide)-2,6-diyl]-alt-5,5′- (2,2′-bithiophene)}, P(NDI2OD-T2)) wurden auf steife Oberflächen mittels Tauchbeschichtung aufgebracht. Da sist das erste Mal, dass es gelungen ist, Polymer Monolagen aus der Lösung aufzubringen. Dieser Ansatz kann weiter auf eine breite Reihe von anderen konjugierten Polymeren ausgeweitet werden.rnIn Kapitel 8 wurden PDI-CN2 Filme erfolgreich von Monolagen zu Bi- und Tri-Schichten auf Oberflächen aufgebracht, die unterschiedliche Rauigkeiten besitzen. Für das erste Mal, wurde der Einfluss der Rauigkeit auf Lösungsmittel-verarbeitete dünne Schichten klar beschrieben.rnThis thesis focuses on controlling the self-assembly and microstructure evolution of semiconductor molecules and their applications in OFETs. In chapter 3, 4, and 5, a novel solution processing method solvent vapor diffusion (SVD) was designed to tune the self-assembly of semiconductor molecules on the surface. This method was proven to be a powerful tool which allowed a delicate control over the microstructure as presented in chapter 3 for a D-A dyad composed of covalently bonded hexa-peri-hexabenzocoronene (HBC) as donor and perylene diimide (PDI) as acceptor (HBC-PDI). The combination of surface modification and solvent vapor can balance dewetting effects and the above mentioned various forces, and finally the desired microstructure and molecular organization on the surface can be achieved. In chapter 4 and chapter 5, SVD was further proven to be a versatile approach to control the (macro) molecular self-assembly on the example of dithieno[2, 3-d;2’, 3’-d’] benzo[1,2-b;4,5-b’]dithiophene (DTBDT) and cyclopentadithiophene -benzothiadiazole copolymer (CDT-BTZ copolymer). These results and strategies may stimulate further study and shed light on the other high performance conjugated polymers for achieving their unprecedented device performances.rnIn chapter 6 and chapter 7 monolayers and their subsequent microstructures of two high performance conjugated polymers (p-type Poly (2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) PBTTT and n-type poly{[ N , N ′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′- (2,2′-bithiophene)}, P(NDI2OD-T2)) on a rigid surface were obtained by dip coating. This is the first time that polymer monolayers were successfully fabricated by solution processing. This approach can be further exploited for a broad range of other high performance conjugated polymers.rnIn chapter 8 PDI8-CN2 films from monolayer to bi/tri layers were successfully fabricated on substrates with different surface roughness. This is for the first time that the effect of surface roughness on solution-processed ultrathin layers was clearly illustrated.r
Pet boarding company service model
No full textThe contemporary generation is increasingly preferring pets over starting families, citing both economic and emotional reasons. This shift has led to a surge in pet adoption rates in China, though travel-related concerns due to limited airline and accommodation provisions for pets persist. The study proposes a digital platform to link pet owners with qualified caretakers, circumventing traditional pet care shortcomings. Drawing parallels with mature Western pet markets, China's burgeoning pet sector presents vast potential for investors. The proposed online platform aims to revolutionize the pet industry by addressing its current challenges and anticipates strong profitability in the coming years.Commerce and MarketingBSc/B
Control over microstructure evolution and device performance in solution processable organic field-effect transistors
No full textDie Arbeit beschäftigt sich mit der Kontrolle von Selbstorganisation und Mikrostruktur von organischen Halbleitern und deren Einsatz in OFETs. In Kapiteln 3, 4 und 5 eine neue Lösungsmittel-basierte Verabeitungsmethode, genannt als Lösungsmitteldampfdiffusion, ist konzipiert, um die Selbstorganisation von Halbleitermolekülen auf der Oberfläche zu steuern. Diese Methode als wirkungsvolles Werkzeug erlaubt eine genaue Kontrolle über die Mikrostruktur, wie in Kapitel 3 am Beispiel einer D-A Dyad bestehend aus Hexa-peri-hexabenzocoronene (HBC) als Donor und Perylene Diimide (PDI) als Akzeptor beweisen. Die Kombination aus Oberflächenmodifikation und Lösungsmitteldampf kann die Entnetzungseffekte ausgleichen, so dass die gewüschte Mikrostruktur und molekulare Organisation auf der Oberfläche erreicht werden kann. In Kapiteln 4 und 5 wurde diese Methode eingesetzt, um die Selbstorganisation von Dithieno[2, 3-d;2’, 3’-d’] benzo[1,2-b;4,5-b’]dithiophene (DTBDT) und Cyclopentadithiophene -benzothiadiazole copolymer (CDT-BTZ) Copolymer zu steuern. Die Ergebnisse könnten weitere Studien stimulieren und werfen Licht aus andere leistungsfaähige konjugierte Polymere. rnIn Kapiteln 6 und 7 Monolagen und deren anschlieβende Mikrostruktur von zwei konjugierten Polymeren, Poly (2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) PBTTT und Poly{[N,N ′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis (dicarboximide)-2,6-diyl]-alt-5,5′- (2,2′-bithiophene)}, P(NDI2OD-T2)) wurden auf steife Oberflächen mittels Tauchbeschichtung aufgebracht. Da sist das erste Mal, dass es gelungen ist, Polymer Monolagen aus der Lösung aufzubringen. Dieser Ansatz kann weiter auf eine breite Reihe von anderen konjugierten Polymeren ausgeweitet werden.rnIn Kapitel 8 wurden PDI-CN2 Filme erfolgreich von Monolagen zu Bi- und Tri-Schichten auf Oberflächen aufgebracht, die unterschiedliche Rauigkeiten besitzen. Für das erste Mal, wurde der Einfluss der Rauigkeit auf Lösungsmittel-verarbeitete dünne Schichten klar beschrieben.rnThis thesis focuses on controlling the self-assembly and microstructure evolution of semiconductor molecules and their applications in OFETs. In chapter 3, 4, and 5, a novel solution processing method solvent vapor diffusion (SVD) was designed to tune the self-assembly of semiconductor molecules on the surface. This method was proven to be a powerful tool which allowed a delicate control over the microstructure as presented in chapter 3 for a D-A dyad composed of covalently bonded hexa-peri-hexabenzocoronene (HBC) as donor and perylene diimide (PDI) as acceptor (HBC-PDI). The combination of surface modification and solvent vapor can balance dewetting effects and the above mentioned various forces, and finally the desired microstructure and molecular organization on the surface can be achieved. In chapter 4 and chapter 5, SVD was further proven to be a versatile approach to control the (macro) molecular self-assembly on the example of dithieno[2, 3-d;2’, 3’-d’] benzo[1,2-b;4,5-b’]dithiophene (DTBDT) and cyclopentadithiophene -benzothiadiazole copolymer (CDT-BTZ copolymer). These results and strategies may stimulate further study and shed light on the other high performance conjugated polymers for achieving their unprecedented device performances.rnIn chapter 6 and chapter 7 monolayers and their subsequent microstructures of two high performance conjugated polymers (p-type Poly (2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) PBTTT and n-type poly{[ NN ′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′- (2,2′-bithiophene)}, P(NDI2OD-T2)) on a rigid surface were obtained by dip coating. This is the first time that polymer monolayers were successfully fabricated by solution processing. This approach can be further exploited for a broad range of other high performance conjugated polymers.rnIn chapter 8 PDI8-CN2 films from monolayer to bi/tri layers were successfully fabricated on substrates with different surface roughness. This is for the first time that the effect of surface roughness on solution-processed ultrathin layers was clearly illustrated.r
Concerto Competition Final Round
No full textCompetition Coordinator Dr. Roberta Rust
Jury Borivoj Martinic-Jercic, violin (Concertmaster, Santa Fe Opera Orchestra and former concertmanster Phoenix Symphony, Iowa State University) Lydia Artymiw, piano (Avery Fisher Career Grant Recipient, University of Minnesota) Frank Epstein, percussion (Former member Boston Symphony Orchestra, Co-chair Brass & Percussion, New England Conservatory of Music)
Piano Accompanists Joshua Cessna Feruza Dadabaeva Guzal Isametdinova Olga Konovalova Dr. Sheng Yuan Kuan Kristine Mezines Dr. Marina Radiushina
Schedule
9:30 am Session Shuyu Liu - Brahms, Violin Concerto (Dadabaeva) Melanie Riordan - Berg, Violin Concerto (Dr. Kuan) Shuyi Wang - Vieuxtemps, Violin Concerto No. 5 (Cessna) Yue Yang - Prokofiev, Violin Concerto No. 2 (Dr. Kuan) Kayla Williams - Bartok, Viola Concerto (Dr. Kuan)
LUNCH BREAK
1:00 pm Session Suhao Bai - Prokofiev, Piano Concerto No. 3 (Dr. Radiushina) Bailey-Michelle Collins - Gershwin, Piano Concerto in F (Dadabaeva) Kimia Rafieian - Shostakovich, Piano Concerto No. 2 (Dr. Kuan) Leanna Irene Ginsburg - Ibert, Flute Concerto (Dr. Kuan) Lydia Roth - Jolivet, Flute Concerto (Mezines
Novice Teachers’ Voices on Professional Agency and Professional Identity in Finland and China
No full textResearch in novice teachers has been wide and rich because they are experiencing a special period in their career life after spending their childhood in school and freshly graduating from teacher education. At the workplace, novice teachers might be specially treated because they are the newcomers, but they may want to realize some professional ideals. Research in novice teacher’s professional agency and professional identity needs to be enriched. Professional agency can be understood as initiatives taken at the workplace, and professional identity can be a “self” as a professional. Both professional agency and professional identity are complex when socio-cultural contexts and subjective factors are intertwined. However, they are related and interdependent—professional agency externalizes and negotiates professional identity, whereas professional identity internalizes and influences professional agency. By comparing ten novice teachers from China and Finland, the overall aim of this thesis is to investigate the degree of professional agency as well as professional identity from a developmental perspective so that the socio-cultural contexts, especially the education systems in Finland and China, and subjective factors can be understood. In this thesis, five novice teachers from China and five novice teachers from Finland were invited to participate in semi-structured interviews. By adopting thematic analysis, the author has found that how those novice teachers’ voices on professional agency and professional identity are similar or different. The result shows that Finnish novice teachers enjoy a relatively higher degree of professional agency at the workplace, and they seem to be more well-prepared by according to the testimonies in the interviews. Early-childhood teachers’ wellbeing in Finland and China need to be considered in the future educational reforms and development
Filter Paper with Selective Absorption and Separation of Liquids that Differ in Surface Tension
No full textSuperhydrophobic and superoleophilic filter paper was successfully prepared by treating commercially available filter paper with a mixture of hydrophobic silica nanoparticles and polystyrene solution in toluene. Applications of the filter paper in separating liquids with low surface tensions such as oil and ethanol from water were investigated in detail. The oil uptake ability of the superhydrophobic filter paper was evaluated and the results show that the filter paper can selectively adsorb oil floating on a water surface or in aqueous emulsions. Furthermore, filtration of mixtures of oil and water through the paper can reduce the water content in the oil. Additionally, the filter paper can also extract ethanol from homogeneous aqueous solution
Nucleophilic α-Functionalization of Benzyl Amines Using an Engineered Threonine Aldolase
No full textInternational audienc
Size Effect on Energy Characteristics of Axial Flow Pump Based on Entropy Production Theory
No full textTo investigate the size effect on the energy characteristics of axial flow pumps, this study scaled the original model size based on the head similarity principle, resulting in four size schemes (Schemes 2–4 correspond to 3, 5, and 10 times the size of Scheme 1, respectively). By solving the unsteady Reynolds-averaged Navier–Stokes (URANS) equations with the Shear Stress Transport (SST) k-omega turbulence model, the external characteristic parameters and internal flow field structures were predicted. Additionally, the spatial distribution of internal hydraulic losses was analyzed using entropy generation theory. The results revealed three key findings: (1) the efficiency of axial flow pumps significantly improves with increasing size ratio, with Scheme 4 exhibiting a 6.1% efficiency increase compared to Scheme 1; (2) as the size ratio increases, the entropy production coefficients of all hydraulic components decrease, with the impeller and guide vanes in Scheme 4 showing reductions of 55.1% and 56.5%, respectively, compared to Scheme 1; (3) the high entropy generation coefficient regions in the impeller and guide vanes are primarily concentrated near the rim, with their area decreasing as the size ratio increases. Specifically, the entropy production coefficients at the rim of impeller and guide vanes in Scheme 4 decreased by 84.85% and 58.2%, respectively, compared to Scheme 1. These findings provide valuable insights for the selection and optimization of axial flow pumps in applications such as cross-regional water transfer, agricultural irrigation, and urban drainage systems
Microstructure Evolution and Device Performance in Solution-Processed Polymeric Field-Effect Transistors: The Key Role of the First Monolayer
No full text- …
