Spiromorpholinone derivatives were synthesized from androsterone or cyclohexanone in 6 or 3 steps, respectively, and these scaffolds were used for the introduction of a hydrophobic group via a ...nucleophilic substitution. Non-steroidal spiromorpholinones are not active as inhibitors of 17I2-hydroxysteroid dehydrogenase type 3 (17I2-HSD3), but steroidal morpholinones are very potent inhibitors. In fact, those with (S) stereochemistry are more active than their (R) homologues, whereas N-benzylated compounds are more active than their non substituted precursors. The target compounds exhibited strong inhibition of 17I2-HSD3 in rat testis homogenate (87a92% inhibition at 1 mu M).
Abstract
We demonstrated an effective poly(p-chloro-xylylene) (Parylene-C) encapsulation method for MAPbI
3
solar cells. By structural and optical analysis, we confirmed that Parylene-C efficiently ...slowed the decomposition reaction in MAPbI
3
. From a water permeability test with different encapsulating materials, we found that Parylene-C-coated MAPbI
3
perovskite was successfully passivated from reaction with water, owing to the hydrophobic behavior of Parylene-C. As a result, the Parylene-C-coated MAPbI
3
solar cells showed better device stability than uncoated cells, virtually maintaining the initial power conversion efficiency value (15.5 ± 0.3%) for 196 h.
The ability of floating ferns Salvinia to keep a permanent layer of air under water is of great interest, e.g., for drag‐reducing ship coatings. The air‐retaining hairs are superhydrophobic, but have ...hydrophilic tips at their ends, pinning the air–water interface. Here, experimental and theoretical approaches are used to examine the contribution of this pinning effect for air‐layer stability under pressure changes. By applying the capillary adhesion technique, the adhesion forces of individual hairs to the water surface is determined to be about 20 µN per hair. Using confocal microscopy and fluorescence labeling, it is found that the leaves maintain a stable air layer up to an underpressure of 65 mbar. Combining both results, overall pinning forces are obtained, which account for only about 1% of the total air‐retaining force. It is suggested that the restoring force of the entrapped air layer is responsible for the remaining 99%. This model of the entrapped air acting is verified as a pneumatic spring (“air‐spring”) by an experiment shortcircuiting the air layer, which results in immediate air loss. Thus, the plant enhances its air‐layer stability against pressure fluctuations by a factor of 100 by utilizing the entrapped air volume as an elastic spring.
Being a role model for future bioinspired technologies such as drag‐reducing ship coatings, the floating fern Salvinia keeps a permanent air layer under water. Due to its special hair structures, it keeps the air for weeks when submerged (Salvinia effect). Experiments show that this entrapped air volume acts as a pneumatic spring, being the key for the plant's air‐retaining properties.
The hierarchical combination of mineral and biopolymer building blocks is advantageous for the notable properties of structural materials. Integrating silane and cellulose nanofibers into ...high‐performance hybrid aerogels is promising yet remains challenging due to the unsatisfied interface connections. Here, an interfacial engineering strategy is introduced via freeze–drying‐induced wetting and mineralization to reinforce the hierarchical porous cellulose network, resulting in mineral‐coated nanocellulose hybrid aerogels in a simple and consecutive bottom‐up assembly process. With optimized multiscale interfacial engineering between the stiff and soft components, the resulting cellulose‐based hybrid aerogels are endowed with lightweight (>0.7 mg cm−3), superior enhanced mechanical compressibility (>99% strain) within a wide temperature range, as well as super‐hydrophobicity (≈168°) and moisture stability under high humidity (95% relative humidity). Benefiting from these superior characters, the multifunctional hybrid aerogels as effective oil/water absorbents with excellent recyclability, thermal insulators in extreme conditions, and sensitive strain sensors are demonstrated. This assembly approach with optimized interfacial features is scalable and efficient, affording high‐performance cellulose‐based aerogels for various applications.
Mineral‐coated nanocellulose hybrid aerogels are developed by interfacial engineering via a freeze–drying‐induced wetting and mineralization process. The resulting hybrid aerogels show integrated properties of high porosity, mechanical robustness, and compressibility, and superhydro‐phobicity, which exceeds the limitation of the individual constituents. They exhibit multifunctionality in terms of ultrafast oil/water separation and reuse stability, durable thermal management, and pressure sensing.
Methods that predict membrane helices have become increasingly useful in the context of analyzing entire proteomes, as well as in everyday sequence analysis. Here, we analyzed 27 advanced and simple ...methods in detail. To resolve contradictions in previous works and to reevaluate transmembrane helix prediction algorithms, we introduced an analysis that distinguished between performance on redundancy‐reduced high‐ and low‐resolution data sets, established thresholds for significant differences in performance, and implemented both per‐segment and per‐residue analysis of membrane helix predictions. Although some of the advanced methods performed better than others, we showed in a thorough bootstrapping experiment based on various measures of accuracy that no method performed consistently best. In contrast, most simple hydrophobicity scale‐based methods were significantly less accurate than any advanced method as they overpredicted membrane helices and confused membrane helices with hydrophobic regions outside of membranes. In contrast, the advanced methods usually distinguished correctly between membrane‐helical and other proteins. Nonetheless, few methods reliably distinguished between signal peptides and membrane helices. We could not verify a significant difference in performance between eukaryotic and prokaryotic proteins. Surprisingly, we found that proteins with more than five helices were predicted at a significantly lower accuracy than proteins with five or fewer. The important implication is that structurally unsolved multispanning membrane proteins, which are often important drug targets, will remain problematic for transmembrane helix prediction algorithms. Overall, by establishing a standardized methodology for transmembrane helix prediction evaluation, we have resolved differences among previous works and presented novel trends that may impact the analysis of entire proteomes.
•PFOTES was used to enhanced the tribo-polarity and hydrophobicity of CNF-based TENG.•PFOTES-CNF-based TENG exhibit enhanced triboelectric performance.•The Isc reached 9.3 μA, which is about twice ...that of a pure CNF-based TENG.•The PFOTES-CNF-based TENG retains 70% of the initial output at 70% ambient humidity.
Cellulose is the most abundant natural polymer on earth. Because it is renewable, biodegradable, and biocompatible, it offers distinct advantages as a starting material for bio-based triboelectric nanogenerator (bio-TENG). However, weak polarity, poor hydrophobicity, and insufficient functionalization on the natural cellulose surface severely limit the development of high-performance cellulose-based TENGs. In this work, chemical functionalization is employed to control the surface polarizability and hydrophobicity of cellulose nanofibrils (CNFs). Functional groups on the CNF surface are modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (PFOTES) in a straightforward and facile process. Fluorine-bearing silane chains are grafted to the surface of CNFs, which increases their triboelectric charge density and improves their hydrophobicity. Experimental results demonstrate that the surface polarity of CNFs is greatly improved after PFOTES modification. The PFOTES-CNF-based TENG exhibits good resistance to humidity and long-term cycle stability, and it retains 70% of the initial output performance at 70% ambient humidity. The short-circuit current of the PFOTES-CNF-based TENG reached 9.3 μA, which is about twice that of CNF-based TENG prior to modification. These results clearly indicate that PFOTES can be used to control CNF surface polarizability and hydrophobicity, advancing the search for durable, high-performance, degradable bio-TENGs.
Biomimetic exploration of stimuli‐responsive and crack‐resistant hydrogels is of great academic and practical significance, although the rational design of tough hydrogels is limited by insufficient ...mechanism study due to the lack of imaging techniques to “see” hydrogels at mesoscale level. A series of composite hydrogels with compartmentalized thermal response is designed by incorporating aggregation‐ and polarity‐sensitive fluorescent probes in a poly(N‐isopropylacrylamide) (PNIPAM) network grafted with poly(N,N‐dimethylacrylamide) side‐chains. The fluorescence technique is explored as a powerful tool to directly visualize their hydrophilicity‐hydrophobicity transformation and the composition‐dependent microphase separation. Based on the morphological observation and mechanical measurements, the concept of morphomechanics with a comprehensive mechanism clarification is proposed. In this regard, the thermoresponsive toughening is attributed to the formation of multiple noncovalent interactions and the conformational changes of PNIPAM chains. The enhanced fracture energy by crack multifurcation is related to the tearing‐like disruption of weak interfaces between the separated phases.
The direct visualization of microphase separation and easy differentiation of hydrophilicity–hydrophobicity transformation is achieved in a facile, high‐contrast, and noninvasive manner by using luminogens with aggregation‐induced emission as fluorescent indicators. Based on the morphological observation and mechanical study, the concept of morphomechanics with a comprehensive mechanism clarification is proposed.
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