improvements have made polymer based solar cells extremely attractive. They are among the most promising alternative candidates to harvest solar energy in the near future. However, bulk heterojunction (BHJ) polymer solar cells are complex systems, as there are many factors directly affecting the fi nal device performance, e.g., the intrinsic properties of the used polymer and fullerene, fi lm morphology, crystallinity, miscibility between these two components, connection between different layers, and device architecture. Among all, a rational design and synthesis of new polymers with superior intrinsic properties is crucial to the development of high efficiency polymer solar cells. In order to optimize the solar cell effi ciency, tuning the chemical structure to obtain the desired property has been proven to be an effective method, evident by the rapid development in the fi eld of chemical synthesis. Starting from the discovery of photoinduced electron transfer from poly(2-methoxy-5-(2′ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) to fullerene, [ 11 ] followed by the introduction of a second material in a bilayer geometry and afterwards the model BHJ system poly(3-hexylthiophene-2,5-diyl) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM), [ 9,[12][13][14][15] until the development of higher effi cient systems such as poly [[4,8-bis[(2-ethylhexyl)]-phenyl-C71-butyric acid methyl ester (PC 71 BM), [ 16 ] an increase in effi ciency was gained. Following the trend towards more effi cient materials, low band gap polymers were developed by controlling the molecular orbital The best performing low bandgap copolymers PTB series to date which is based on thieno[3,4-b]thiophene-alt-benzodithiophene units blended with[6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM), have been the focus of polymer-based solar cells. Here, novel fl uorinated polymers PTB7-Fx (fl uorine units coupled with submonomer thieno[3,4-b]thiophene) with varied degree of fl uorination are used as electron donor materials. The PTB7-Fx:PC 71 BM bulk heterojunction (BHJ) fi lms spin-coated from the host solvent chlorobenzene without and with solvent additive 1,8-diiodooctane (DIO) and the corresponding solar cell devices are systematically investigated to address the morphology-effi ciency relationship. Self-assembled BHJ morphology is already observed for as-spun blend fi lms. After adding the solvent additive DIO, the pronounced ordered structures are suppressed and better intermixed fi lms with much smaller domain sizes result. Full fl uorination of the third C-atom of thienothiophene gives rise to the highest power conversion effi ciency. As the absorption properties, fi lm morphology and crystallinity remain similar for different degrees of fl uorination, the main infl uence of the photovoltaic performance is ascribed to the different lowest unoccupied molecular orbital (LUMO) of each polymer instead of the fi lm morphology. Thus the device performance can be effi ciently improved by tuning the energy level of the polymer without ...

The control over the alignment of nanoparticles within a block copolymer matrix was investigated for different external magnetic fields with respect to producing well-aligned, highly oriented metal-oxide-polymer nanopatterns. Hybrid films were prepared by solution casting under a range of external magnetic fields. The nano- and microstructure of maghemite nanoparticles within poly(styrene-b-methyl methacrylate) diblock copolymer films as a function of the nanoparticle concentration was studied using optical microscopy, atomic force microscopy, scanning electron microscopy, and grazing incidence small-angle X-ray scattering. Because of a polystyrene (PS) coating, the nanoparticles are incorporated in the PS domains of the diblock copolymer morphology. At higher nanoparticle concentrations, nanoparticle aggregates perturb the block copolymer structure and accumulate at the films surface into wire-shaped stripes. These wire-shaped nanoparticle aggregates form mainly because of the competition between nanoparticle-polymer friction and magnetic dipolar interaction. The magnetic behavior of the hybrid films was probed at different temperatures for two orthogonal directions (with the line-shaped particle aggregates parallel and perpendicular to the magnetic field). The hybrid film systems show superparamagnetic behavior and remarkable shape anisotropy that render them interesting for magnetic applications.

Herein, free-standing supertubes, composed of a single layer of close-packed carbon-coated nanoparticles, are fabricated by a confined-epitaxial-assembly strategy. Benefiting from the tubular geometry, monolayer superlattice structure, and uniform and conformal carbon coating, such free-standing supertubes promise high electrochemical performance while simultaneously serving as a robust platform for reliably elucidating the structure-performance relationship of lithium-ion batteries (LIBs). As a model, Fe 3 O 4 supertubes, when used as LIB anodes, can deliver a capacity of $800 mAh g À1 after 500 cycles at 5 A g À1 , outperforming most Fe 3 O 4-based materials reported previously. More importantly, the structural evolution of Fe 3 O 4 supertubes is revealed at meso-/nano-/atomic scales simultaneously upon lithiation and delithiation, which correlates well with the battery's capacity reactivation, stabilization, and degradation behaviors during the course of 500 cycles.

Background: Recent studies had explored that gut microbiota was associated with neurodegenerative diseases (including Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS)) through the gut-brain axis, among which metabolic pathways played an important role. However, the underlying causality remained unclear. Objective: Our study aimed to evaluate potential causal relationships between gut microbiota, metabolites, and neurodegenerative diseases through Mendelian randomization (MR) approach. Methods: We selected genetic variants associated with gut microbiota traits (N = 18,340) and gut microbiota-derived metabolites (N = 7,824) from genome-wide association studies. Summary statistics of neurodegenerative diseases were obtained from IGAP (AD, 17,008 cases; 37,154 controls), IPDGC (PD, 37,688 cases; 141,779 controls), and IALSC (ALS, 20,806 cases; 59,804 controls) respectively. Results: Greater abundance of Ruminococcus (OR, 1.245; 95% CI, 1.103–1.405; p = 0.0004) was found significantly related to higher risk of ALS. Besides, our study found suggestive associations of Actinobacteria, Lactobacillaceae, Faecalibacterium, Ruminiclostridium, and Lachnoclostridium with AD, of Lentisphaerae, Lentisphaeria, Oxalobacteraceae, Victivallales, Bacillales, Eubacteriumhalliigroup, Anaerostipes, and Clostridiumsensustricto1 with PD, and of Lachnospira, Fusicatenibacter, Catenibacterium, and Ruminococcusgnavusgroup with ALS. Our study also revealed suggestive associations between 12 gut microbiome-dependent metabolites and neurodegenerative diseases. Glutamine was related to lower risk of AD. For the serotonin pathway, serotonin was found as a protective factor of PD, while kynurenine as a risk factor for ALS. Conclusion: Our study firstly applied a two-sample MR approach to detect causal relationships among gut microbiota, gut metabolites, and neurodegenerative diseases. Our findings may provide new targets for treatments and may offer valuable insights for further studies on the underlying mechanisms.