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Helix structures, which are frequently observed in nature, act as versatile structural templates for complex functionalities with asymmetry and anisotropy. However, atomically thin 2D materials, including graphene, transition metal dichalcogenides (TMDs), and MXenes, do not have inherent chirality in their planar geometry and cannot easily form such a structure. This study presents the macroscopic self‐assembly of 2D materials for helical screws with an Archimedean spiral arrangement. The naturally triggered spontaneous rotation upon the 1D fiber assembly of 2D materials forms helical screws consisting of multiple helices and perversions. For a clear understanding of the morphological evolution of helical screws, variations in the helical pitch and angle are systematically analyzed considering thermodynamic and kinetic conditions. Subsequently, the influence of spontaneous helix formation on the properties of the 2D assembled fibers is investigated in terms of the solvent‐driven actuator performance and electrical and electrothermal properties. The suggested approach provides a new perspective on the directed self‐assembly of inherently achiral 2D materials toward chiral helix formation. [ABSTRACT FROM AUTHOR]

The development of synthetic methods to produce highly functionalized chiral 3‐pyrrolines is of indisputable importance because of their prevalence in natural and synthetic bioactive molecules. Unfortunately, previous general cycloaddition approaches using allenoates, could not synthesize 3,4‐disubstituted 3‐pyrrolines. Herein, an original approach to yield 2,3,4‐trisubstituted 3‐pyrrolines with chirality at the 2‐position is presented. A NiII/Fc‐i‐PrPHOX catalytic system facilitated a redox‐neutral highly stereoselective process that exhibited an enantioselectivity of up to 99 %. Enantioenriched 3‐pyrrolines can be converted to other valuable classes of N‐heterocycles. [ABSTRACT FROM AUTHOR]

BiVO4 crystals synthesized by an ultrasonic‐assisted method (Sono‐BiVO4) showed improved efficiency as a heterogeneous photocatalyst under visible‐light irradiation. Sono‐BiVO4 was successfully used for the C−C bond cleavage of alkenes to generate carbonyl compounds. Styrene derivatives were converted into carbonyl compounds in the presence of Sono‐BiVO4 under highly sustainable conditions requiring only natural sources, that is, molecular oxygen, visible light, and water at room temperature. Additionally, Sono‐BiVO4 could be easily separated from the reaction mixture and reused. [ABSTRACT FROM AUTHOR]

Abstract: A method has been developed for the synthesis of fluoroalkylated oximes, potential fluoroalkyl building‐blocks for the synthesis of various organofluorine compounds, from easily available amino substrates and fluoroalkylated alkenes. tBuONO was utilized both as a diazotizing agent and as a NO radical source for the oxime synthesis in the process, and the use of a photocatalyst under visible‐light irradiation increased the efficiency of the reaction. Various fluoroalkylated oximes were prepared by a tandem process of aryl radical addition to fluoroalkylated alkene and consecutive oxime generation process, albeit in moderate yields. This differentiated approach, transferring an aromatic system into an electron‐deficient fluoroalkylated alkene, expands the scope of substrates where electron‐poor aromatic systems could be utilized. [ABSTRACT FROM AUTHOR]

During the last three decades progress in mapping the Universe from an age of 400 000 years to the present has been stunning. Instrument/telescope combinations have naturally determined the sampling of various redshift ranges. Here we outline the impact of the Hectospec on the MMT on exploration of the Universe in the redshift range 0.2 ≲ z ≲ 0.8. We focus on dense redshift surveys, SHELS and HectoMAP. SHELS is a complete magnitude limited survey covering 8 square degrees. The HectoMAP survey combines a red-selected dense redshift survey and a weak lensing map covering 50 square degrees. Combining the dense redshift survey with a Subaru HyperSuprimeCam (HSC) weak lensing map will provide a powerful probe of the way galaxies trace the distribution of dark matter on a wide range of physical scales. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Electrospun fibrous mats have gained popularity in bioengineering over the past decade, but few papers detail their degradative mechanisms. To address this, blends of hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic PGA-PCL-PGA triblock copolymer were electrospun into aligned fibrous mats to assess the copolymers' mechanical and degradative properties. Increased hydrophilic triblock content led to enhanced morphological uniformity of fiber, tightening of fiber diameters, increased storage and Young's modulus, and decreased elongation. The corresponding decrease in hydrophobic PCL content led to faster hydrolytic degradation rate, as reflected by enhanced decrease in mass, molecular weight, and modulus loss at 25, 37, and 45°C. The activation energy for hydrolytic degradation for 15:85 PCL: triblock copolymer was approximately half that of 85:15 PCL: triblock copolymer. Detailed examination of fiber morphology and crystallinity revealed initial surface erosion followed by the evolution of crystalline lamellar stacks and bulk degradation at 37°C. Because of the high surface to volume and short diffusion length scale of the small diameter fibers, surface and bulk degradation may both contribute to the hydrolytic degradative behavior of these electrospun fibrous mats. Electrospun mats' distinct architecture that embodies high specific surface to volume and interfiber porous ultrastructures that lead to their unique degradative behaviors hold much potential for significant impact in the field of tissue engineering and controlled drug delivery. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. [ABSTRACT FROM AUTHOR]