The role of solution aggregates on the charge transport process of conjugated polymers in electronic devices has gained increasing attention; however, the correlation of the charge carrier mobilities ...between the solution aggregates and the solid‐state films remains elusive. Herein, three polymers, FBDOPV‐2T, FBDOPV‐2F2T, and FBDOPV‐4F2T, are designed and synthesized with distinct aggregation behavior in solution. By combining contact‐free ultrafast terahertz (THz) spectroscopy and field‐effect transistor measurements, we track the charge carrier mobility of the aggregates of these polymers from the solution to the thin‐film state. Remarkably, the mobility of these three polymers is found to follow nearly the same trend (FBDOPV‐2T>FBDOPV‐2F2T≫FBDOPV‐4F2T) in both solutions and thin‐film states. The quantitative mobility correlation indicates that the charge transport properties of solution aggregates play a critical role in determining the thin‐film charge transport properties and final device performance. Our results highlight the importance of investigating and controlling solution aggregation structures towards efficient organic electronic devices.
Different aggregation structures of three BDOPV‐based polymers in solution were obtained via subtle adjustment of the molecular structures. By employing contact‐free ultrafast terahertz (THz) spectroscopy, we directly reveal that the correlation of the charge carrier mobilities between the solution aggregates and the solid‐state films remains highly consistent.
Solution‐processable highly conductive polymers are of great interest in emerging electronic applications. For p‐doped polymers, conductivities as high a nearly 105 S cm−1 have been reported. In the ...case of n‐doped polymers, they often fall well short of the high values noted above, which might be achievable, if much higher charge‐carrier mobilities determined could be realized in combination with high charge‐carrier densities. This is in part due to inefficient doping and dopant ions disturbing the ordering of polymers, limiting efficient charge transport and ultimately the achievable conductivities. Here, n‐doped polymers that achieve a high conductivity of more than 90 S cm−1 by a simple solution‐based co‐deposition method are reported. Two conjugated polymers with rigid planar backbones, but with disordered crystalline structures, exhibit surprising structural tolerance to, and excellent miscibility with, commonly used n‐dopants. These properties allow both high concentrations and high mobility of the charge carriers to be realized simultaneously in n‐doped polymers, resulting in excellent electrical conductivity and thermoelectric performance.
Two conjugated polymers with rigid planar backbones, but with disordered crystalline structures, exhibit surprising structural tolerance to commonly used n‐dopants. These properties allow both high concentrations and high mobility of the charge carriers to be realized simultaneously in n‐doped polymers, resulting in excellent electrical conductivity of over 90 S cm−1 and thermoelectric performance up to 106 µW m−1 K−2.
I study the welfare implications of corporate taxation in the presence of multinational production (MP) to understand the consequences of international tax competition and cooperation. I build a ...quantifiable general equilibrium model with trade, MP, and salient features of international corporate tax system. The model delivers structural equations that can be used to estimate the key parameters governing the response of firms' production locations to changes in corporate tax rates. Calibrating the model to data on 28 countries, I find that the U.S. corporate tax reform in 2017 increases the U.S. real income by about 1% but decreases the average real income of other countries by 0.075%. In a non-cooperative tax game, each country has strong incentives to lower its corporate tax rate on domestic firms in order to gain from firm relocation at the expense of other countries, which leads to welfare losses in participation countries. International tax cooperation can increase the real income in each participation country by about 1%.
•Corporate taxes impede multinational production, with global welfare implications.•The U.S. corporate tax reform in 2017 increases the U.S. real income by about 1%.•Countries favor domestic firms in tax competition, leading to welfare losses.•International tax cooperation can increase the global real income by 1%.
A
bstract
Positivity bounds are powerful tools to constrain effective field theories. Utilizing the partial wave expansion in the dispersion relation and the full crossing symmetry of the scattering ...amplitude, we derive several sets of generically nonlinear positivity bounds for a generic scalar effective field theory: we refer to these as the
P Q
,
D
su
,
D
stu
and
D
¯
stu
bounds. While the
PQ
bounds and
D
su
bounds only make use of the
s
↔
u
dispersion relation, the
D
stu
and
D
¯
stu
bounds are obtained by further imposing the
s
↔
t
crossing symmetry. In contradistinction to the linear positivity for scalars, these inequalities can be applied to put upper and lower bounds on Wilson coefficients, and are much more constraining as shown in the lowest orders. In particular we are able to exclude theories with soft amplitude behaviour such as weakly broken Galileon theories from admitting a standard UV completion. We also apply these bounds to chiral perturbation theory and we find these bounds are stronger than the previous bounds in constraining its Wilson coefficients.
Hantzsch esters were often previously used as reductants in thermal catalytic hydrogenation reactions. Over the last few decades, Hantzsch esters have proven to be a useful class of electron donors ...and proton sources in photoredox catalyzed processes. Moreover, under photoredox catalytic conditions, alkyl-1,4-dihydropyridines can serve as versatile types of alkylation reagents
via
oxidative fragmentation mechanisms. This minireview highlights the recent advances in the chemistry of Hantzsch esters in photoredox catalyzed organic synthesis, with particular emphasis placed on reaction mechanisms. We hope that this review will inspire further new reaction design and developments with such a class of readily accessible reagents.
This minireview highlights the recent advances in the chemistry of Hantzsch esters in photoredox catalyzed organic synthesis, with particular emphasis placed on reaction mechanisms.
Traditional Chinese medicine (TCM) is a precious treasure of the Chinese nation and has unique advantages in the prevention and treatment of diseases. The holistic view of TCM coincides with the new ...generation of medical research paradigm characterized by network and system. TCM gave birth to a new method featuring holistic and systematic “network target”, a core theory and method of network pharmacology. TCM is also an important research object of network pharmacology. TCM network pharmacology, which aims to understand the network-based biological basis of complex diseases, TCM syndromes and herb treatments, plays a critical role in the origin and development process of network pharmacology. This review introduces new progresses of TCM network pharmacology in recent years, including predicting herb targets, understanding biological foundation of diseases and syndromes, network regulation mechanisms of herbal formulae, and identifying disease and syndrome biomarkers based on biological network. These studies show a trend of combining computational, experimental and clinical approaches, which is a promising direction of TCM network pharmacology research in the future. Considering that TCM network pharmacology is still a young research field, it is necessary to further standardize the research process and evaluation indicators to promote its healthy development.
AbstractUnderstanding the effect of particle size on the shear strength of granular materials is important for geotechnical design and construction. However, previous studies show contradicting ...results on the relationship between particle size and shear strength. Additionally, the effect of particle breakage on this relationship has not been fully revealed. In this study, a series of biaxial tests have been simulated with the discrete element method to explore the particle-size effect of sand considering the role of particle breakage. The sand specimens have parallel particle-size distributions. The sequential breakage model has been used to simulate particle breakage, which is a combination of replacement and cluster methods. The main conclusions of this study are: (1) the relationship of peak shear strength and particle size depends on the crushability of particles and relative density of specimens; (2) the particle size and crushability have a very slight effect on the residual shear strength; and (3) at the microscale, the relationship between shear strength and particle size is positively related to the friction utilization ratio.
Haploinsufficiency of the SHANK3 gene is causally linked to autism spectrum disorder (ASD), and ASD-associated genes are also enriched for chromatin remodelers. Here we found that brief treatment ...with romidepsin, a highly potent class I histone deacetylase (HDAC) inhibitor, alleviated social deficits in Shank3-deficient mice, which persisted for ~3 weeks. HDAC2 transcription was upregulated in these mice, and knockdown of HDAC2 in prefrontal cortex also rescued their social deficits. Nuclear localization of β-catenin, a Shank3-binding protein that regulates cell adhesion and transcription, was increased in Shank3-deficient mice, which induced HDAC2 upregulation and social deficits. At the downstream molecular level, romidepsin treatment elevated the expression and histone acetylation of Grin2a and actin-regulatory genes and restored NMDA-receptor function and actin filaments in Shank3-deficient mice. Taken together, these findings highlight an epigenetic mechanism underlying social deficits linked to Shank3 deficiency, which may suggest potential therapeutic strategies for ASD patients bearing SHANK3 mutations.
Context: Scutellaria baicalensis Georgi (Lamiaceae) is a popular medicinal plant. Its roots are used as the famous traditional Chinese medicine Huang-Qin, which is recorded in Chinese Pharmacopoeia, ...European Pharmacopoeia, and British Pharmacopoeia.
Objective: This review comprehensively summarizes research progress in phytochemistry, pharmacology, and flavonoid biosynthesis of S. baicalensis.
Methods: English and Chinese literature from 1973 to March 2018 was collected from databases including Web of Science, SciFinder, PubMed, Elsevier, Baidu Scholar (Chinese), and CNKI (Chinese). Scutellaria baicalensis, chemical constituents, phytochemistry, biological activities, and biosynthesis were used as the key words.
Results: A total of 126 small molecules (1-126) and 6 polysaccharides have been isolated from S. baicalensis. The small molecules can be classified into four structural types, namely, free flavonoids, flavonoid glycosides, phenylethanoid glycosides, and other small molecules. Extracts of S. baicalensis and its major chemical constituents have been reported to possess anti-viral, anti-tumor, anti-bacterial, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective activities. Key steps in the biosynthetic pathways of Scutellaria flavonoids have also been summarized.
Conclusions: This article could be helpful for researchers who are interested in the chemical constituents, bioactivities, biosynthesis, and clinical applications of S. baicalensis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Controlling the solution‐state aggregation of conjugated polymers for producing specific microstructures remains challenging. Herein, a practical approach is developed to finely tune the solid‐state ...microstructures through temperature‐controlled solution‐state aggregation and polymer crystallization. High temperature generates significant conformation fluctuation of conjugated backbones in solution, which facilitates the polymer crystallization from solvated aggregates to orderly packed structures. The polymer films deposited at high temperatures exhibit less structural disorders and higher electron mobilities (up to two orders of magnitude) in field‐effect transistors, compared to those deposited at low temperatures. This work provides an effective strategy to tune the solution‐state aggregation to reveal the relationship between solution‐state aggregation and solid‐state microstructures of conjugated polymers.
Using temperature‐controlled polymer aggregation, the solid‐state microstructures of conjugated polymers are finely tuned. The temperature‐controlled strategy enhances the molecular ordering in thin films and leads to efficient charge transport. A polymer transistor with tuned molecular ordering exhibited improved electron mobilities of up to 3.71 cm2 V−1 s−1, which is two orders of magnitude higher than the disordered samples.
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