Spherical Indicatrices of a Bertrand Curve in Three Lie Groups

In this paper, new representations of a Bertrand curve pair in three dimensional Lie groups with bi-invariant metric are given. Besides, the spherical indicatrices of a Bertrand curve pair are obtain and the relations between the spherical indicatrices and new representations of Bertrand curve pair are shown.Comment: 12 page

In Situ TEM-STM Recorded Kinetics of Boron Nitride Nanotube Failure under Current Flow

Joule-heating-induced failure of individual multiwalled boron nitride (BN) nanotubes is investigated in a high-resolution transmission electron microscope (TEM) equipped with a scanning tunneling microscope (STM) unit. Direct observation of the failure process indicates that it occurred via thermal decomposition of tubular layers from inside-out of a tube leaving amorphous ball-like boron-based nanoparticles behind. The electrical transport is well simulated by the thermionic field-emission model. The thermal decomposition temperature, which is deduced from a breakdown curve, shows a dependence on local electrical field; the higher the electrical field, the lower the decomposition temperature. This is attributed to partially ionic nature of a B−N bond

In Situ TEM-STM Recorded Kinetics of Boron Nitride Nanotube Failure under Current Flow

Joule-heating-induced failure of individual multiwalled boron nitride (BN) nanotubes is investigated in a high-resolution transmission electron microscope (TEM) equipped with a scanning tunneling microscope (STM) unit. Direct observation of the failure process indicates that it occurred via thermal decomposition of tubular layers from inside-out of a tube leaving amorphous ball-like boron-based nanoparticles behind. The electrical transport is well simulated by the thermionic field-emission model. The thermal decomposition temperature, which is deduced from a breakdown curve, shows a dependence on local electrical field; the higher the electrical field, the lower the decomposition temperature. This is attributed to partially ionic nature of a B−N bond

Divergent Total Synthesis of Chaetoglines C to F

The first total syntheses of chaetoglines C–F via a bioinspired and divergent synthetic strategy are reported. Chaetolines C and D were obtained from the condensation of hemiacetal and tryptophan methyl ester building blocks followed by functional group transformations. The synthesis of chaetogline E employed the diastereoselective Pictet–Spengler reaction, and the tetrahydro-carboline skeleton was further utilized as a precursor for an oxidative aromatization reaction to introduce the β-carboline moiety of chaetogline F

Multiwall Carbon Nanotubes Made of Monochirality Graphite Shells

A multiwall carbon nanotube (MWCNT) consists of several or many concentric carbon shells, each of which could be metallic or semiconducting. Both theoretical predictions and experimental results suggest that MWCNTs have exotic electronic structures and intriguing transport properties, which are highly dependent on chirality of each shell. However, the structural defects and the random distribution of chirality of each concentric graphitic shell make the MWCNTs difficult for basic research and technological applications. Thus far, it is still a challenge to get the high crystalline MWCNTs with limited atomic conformation. Here, we report the synthesis of high crystalline MWCNTs made of monochirality graphite shells by a low-temperature chemical vapor deposition (CVD) process in plasma environment. Structural analysis, carried out by transmission electron microscopy (TEM) image and electron diffraction methods, reveal that the MWCNTs are well-crystallized and that most of them have nearly identical chiralities

Atomic Mechanism of Dynamic Electrochemical Lithiation Processes of MoS₂ Nanosheets

Layered molybdenum disulfide (MoS₂) has been studied for decades for its diversity of structure and properties, where the structural dynamic evolution during lithium intercalation is an important but still indistinct, controversial topic. Here the electrochemical dynamic process of MoS₂ nanosheets upon lithium intercalation has been systematically investigated by <i>in situ</i> high-resolution transmission electron microscopy. The results indicate that the lithiated MoS₂ undergoes a trigonal prismatic (2H)-octahedral (1T) phase transition with a lithium ion occupying the interlayer S–S tetrahedron site in the 1T-LiMoS₂. A pseudoperiodic structural modulation composed of polytype superlattices is also revealed as a consequence of the electron–lattice interaction. Furthermore, the shear mechanism of the 2H-1T phase transition has been confirmed by probing the dynamic phase boundary movement. The <i>in situ</i> real-time characterization at atomic scale provides a great leap forward in the fundamental understanding of the lithium ion storage mechanism in MoS₂, which should be also of help for other transition metal dichalcogenides

Synthesis of Triphenylamine-Cored Dendritic Two-Photon Absorbing Chromophores

A new series of dendritic two-photon absorbing chromophores containing triphenylamine moiety as a core or branching points have been synthesized through a convergent synthetic strategy. One-photon and two-photon optical properties of these molecules were characterized. In the nanosecond time domain, these molecules exhibited large two-photon absorption (TPA) cross sections up to 7.56−12.2 × 10-44 s cm4 at 800 nm, indicating that these molecular structures were viable candidates for various two-photon related applications

Table_1_Non-palm Plant Volatile α-Pinene Is Detected by Antenna-Biased Expressed Odorant Receptor 6 in the Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae).DOCX

The majority of insects rely on a highly complex and precise olfactory system to detect various volatile organic compounds released by host and non-host plants in environments. The odorant receptors (ORs) are considered to play an important role in odor recognition and the molecular basis of ORs, particularly in coleopterans they are relatively poorly understood. The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is one of the most destructive pests of the global palm industry. Although feeding and egg oviposition behaviors of RPW can be repelled by some non-palm plant volatiles, such as α-pinene, geraniol, or 1-octen-3-ol, there is limited understanding of how RPW recognizes the non-host plant volatiles. In this study, three candidate RferOrs were identified from the Rfer-specific clade, and the tissue expression analysis used was mainly expressed in the antennae of both sexes. Functional characterization of RferOr6, RferOr40, and RferOr87 was analyzed by using the Xenopus oocyte expression system, and the results indicated that RferOr6/RferOrco was narrowly tuned to α-pinene. The behavioral experiment showed that α-pinene at the concentrations of 10 and 100 μg/μl can cause a significantly repelled behavioral response of RPW. In conclusion, this study reveals that RferOr6 is an antenna-biased expressed OR used by RPW to detect the volatile compound α-pinene in non-palm plants, and our results provide a foundation for further in vivo functional studies of Or6 in RPW, including in vivo knockout/knockdown and feeding/ovipositing behavioral studies of RPW and further pest control.</p

Uniform and Persistent Jumping Detachment of Condensed Nanodroplets

Realizing jumping detachment of condensed droplets from solid surfaces at the smallest sizes possible is vital for applications such as antifogging/frosting and heat transfer. For instance, if droplets uniformly jump at sizes smaller than visible light wavelengths of 400–720 nm, antifogging issues could be resolved. In comparison, the smallest droplets experimentally observed so far to jump uniformly were around 16 μm in radius. Here, we show molecular dynamics (MD) simulations of persistent droplet jumping with a uniform radius down to only 3.6 nm on superhydrophobic thin-walled lattice (TWL) nanostructures integrated with superhydrophilic nanospots. The size cutoff is attributed to the preferential cross-lattice coalescence of island droplets. As an application, the MD results exhibit a 10× boost in the heat transfer coefficient (HTC), showing a −1 scaling law with the maximum droplet radius. We provide phase diagrams for jumping and wetting behaviors to guide the design of lattice structures with advanced antidew performance

Selective Swelling of Electrospun Block Copolymers: From Perforated Nanofibers to High Flux and Responsive Ultrafiltration Membranes

This work is devoted to the development of high-flux ultrafiltration membranes using electrospun nanofibers of amphiphilic block copolymers (BCPs) of polystyrene-<i>block</i>-poly­(2-vinylpyridine) (PS-<i>b</i>-P2VP) as building blocks. When soaked in hot ethanol, the solid as-spun BCP fibers are progressively transformed into three-dimensionally perforated fibers with increasing porosities with rising degrees of swelling, which ended up with the equilibrated morphology of spherical micelles. The BCP nanofibers are collected on macroporous substrates and subjected to heating to convert loosely stacked fibers to dense and continuous films. Subsequent swelling in hot ethanol leads to robust composite membranes with nanoporous BCP selective layers tightly adhered to the substrates. Filtration performances of the composite membranes can be conveniently modulated by electrospinning durations. The water permeabilities are as high as 6100 L m^–2 h^–1 bar^–1, which is ∼10–35 times higher than that of commercial membranes with similar rejections. Moreover, with the surface enrichment of P2VP chains the membranes exhibit a strikingly sharp pH-dependent water permeability switchable in the largest amplitude ever reported for multiple cycles. Electrospun fibers can be promising building materials to produce a wide range of membranes with 3D interconnected nanoporosities which also show great potential in separation and biomedical applications