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• The paper discusses the significant challenge in analytical chemistry of determining chirality in solid materials using electron paramagnetic resonance (EPR) spectroscopy. • The paper introduces a novel approach using electron paramagnetic resonance (EPR) spectroscopy on chiral crystals doped with Cu2+ ions to determine chirality of crystals. • The method is demonstrated using l - and DL-Histidine crystals doped with Cu2+, showing promising results in accurately determining chirality and enantiomeric composition. • This work provides an initial example of this technique and envisions its potential application to various other chiral organic crystal systems in the future. One of the most challenging tasks in analytical chemistry is the determination of the chirality (identification of an enantiomeric composition) in solids mainly because of the strict requirements of the pharmaceutical industry for enantiomerically pure drugs. Although there are a few methods available to accomplish enantio‑differentiation in solids, for example: X-ray diffraction (XRD), Thermogravimetric analysis (TGA), CD spectroscopy, and low-frequency (LF) Raman spectroscopy, this is still very challenging. In this work, we have developed a new method to measure the chirality of crystals, based on electron paramagnetic resonance (EPR) spectroscopy of chiral crystals doped with Cu2+ as the EPR active ion. Here, we demonstrate our approach using a model system of l - and DL-Histidine crystals doped with Cu2+. We show that EPR measurements of the Cu2+-doped Histidine crystals can accurately determine the chirality and enantiomeric composition of the crystals. We present a very preliminary example of this technique, and we hope that in the future it will be possible to refine and develop this method for many other chiral organic crystal systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanomaterials with different characteristics are offering many ingenious sensing approaches with interest for simple and disposable paper-based (bio)sensing applications. In this study, the colorimetric discrimination of alanine enantiomers is examined and, more importantly, AuNPs-embedded paper-based lab-in-a-syringe (LIS) device is developed as a sensing strategy. The LIS consists of two cellulose acetate membranes: the conjugate pad capturing the analyte and the detection pad signaling the presence of the captured analyte, both are sandwiched between reusable plastic filter holders connected to a disposable syringe. The principle of LIS assay is based on the enantioselective interaction occurring between the inherently chiral AuNPs and enantiomers in the first filter holder, which results in aggregation of AuNPs to give a distinct colour change from red to purple in solution and finally the aggregated AuNPs is kept on the detection pad through vertical-flow operation. AuNPs show an enantioselective recognition response toward L -Alanine and limit of detection (LOD) value is determined as 0.77 mM. In addition, we demonstrate the efficiency of the LIS device for detecting L -Alanine in human serum. The proposed LIS assay has some advantages such as useful for naked-eye observation, disposable, not time-consuming, inexpensive, no need of advanced instruments, easy to prepare and easy to handle. In the field, the approach which is the first demonstration of applicability of LIS device to show simple colorimetric enantioselective sensing of chiral species with a fast readout in less than 5 min is truly new and may have broad interest in enantiosensing of various chiral molecules. [ABSTRACT FROM AUTHOR]

• Chiral invariants before and after reflection are opposite to each other. • Brief form, low time complexity (O (n)), order and degree are no more than four. • Determining the global symmetry plane and coping with false zeros problems. Chirality describes the structural properties or configuration of an object, and it plays an important role in fields such as physics, chemistry and biology. It is critical to identify achiral objects and determine symmetry plane of them in shape analysis, and chiral invariants play essential role in above tasks. However, chiral invariants are often complex and time-consuming to calculate in practical applications. In this paper, we present five chiral invariants based on the concept of generating functions. Three of the five chiral invariants decode the expression of a chiral index, and they are the core part of this chiral index. In addition, this paper provides three new chiral invariants. These five chiral invariants have three characteristics: (1) Their results on the shape before and after the reflection transformation are opposite to each other. (2) The five chiral invariants have brief form and low time complexity (O (n)), the order and degree of them are not more than four. (3) They can be used to determine the global symmetry plane of reflection symmetry objects, and they help to deal with false zeros problem. The five chiral invariants give the invariants under reflection transformation from the geometrical point of view, and the experimental results show that they are effective and efficient. In conclusion, our invariants can be used for determining archiral objects and mutual symmetry shape, as well as for determining symmetry plane of reflection symmetry objects. [ABSTRACT FROM AUTHOR]

Consider a group of autonomous mobile computational entities, called agents, arbitrarily placed at some nodes of a dynamic but always connected ring. The agents neither have any knowledge about the size of the ring nor have a common notion of orientation. We consider the Exploration problem where the agents have to collaboratively explore the graph and terminate, with the requirement that each node has to be visited by at least one agent. It has been shown by Luna et al. (2020) [22] that the problem is solvable by two anonymous agents if there is a single observably different node in the ring called landmark node. The problem is unsolvable by any number of anonymous agents in absence of a landmark node. We consider the problem with non-anonymous agents (agents with distinct identifiers) in a ring with no landmark node. The assumption of agents with distinct identifiers is strictly weaker than having a landmark node as the problem is unsolvable by two agents with distinct identifiers in absence of a landmark node. This setting has been recently studied by Mandal et al. (2020) [6]. There it is shown that the problem is solvable in this setting by three agents assuming that they have edge crossing detection capability. Edge crossing detection capability is a strong assumption which enables two agents moving in opposite directions through an edge in the same round to detect each other and also exchange information. In this paper we give an algorithm that solves the problem with three agents without the edge crossing detection capability. • Exploration of a dynamic but always connected ring by autonomous agents is studied. • A deterministic protocol is given that solves the problem with explicit termination. • The agents have unique identifiers, but do not have chirality or edge crossing detection capability. • The algorithm solves the problem with optimum number of agents. • A new problem called Contiguous Agreement is introduced and solved. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • L -cysteine modified chiral carbon quantum dots (cCQDs) were synthesized. • cCQDs-embedded nanopaper is developed for enantioselective sensing. • Photoluminescent enantioselective sensing of lysine enantiomers is achieved. • The enantiomeric percentage can be determined by the proposed sensor. Abstract The production and application of chiral nanomaterials are expanding to understand the nature of chiral interactions and to detect chiral molecules due to the chirality is a fundamental characteristics of life processes. With the new advances in optical sensors by combining the advantages of optical signaling unit and sensing platform, new avenues can be opened to produce simple and useful devices for chiral sensor applications. Here, we report construction of nanoscale chirality of carbon quantum dots (CQDs) by functionalization with L -cysteine and application for paper-based sensors. Within this respect, nanopaper made of cellulose nanofibers was prepared and the produced chiral carbon quantum dots (cCQDs) were embedded into nanopaper to gain photoluminescence properties. The chiral sensing behavior of cCQDs was investigated in solution phase and nanopaper. cCQDs exhibited an enantioselective response towards L -lysine among the tested enantiomers of amino acids with a LOD value of 0.30 mM and 0.97 mM for solution phase and nanopaper, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a continuum-molecular formulation for bi-dimensional micropolar media within the mathematical formalism of a revised peridynamic theory with oriented material points. A variational procedure is considered to derive the fundamental governing equations of the model, which postulates that material points interact through pair potentials allowing generalized pairwise actions to be derived as energy conjugates to properly defined pairwise deformation measures. While continuity of mass is assumed, constitutive laws are produced for long-range micro-interactions to reproduce the effective behavior of the material at the macro-scale. The definition of proper micromoduli functions respecting material symmetries and invariance properties allows then to obtain a non-local micropolar continuum based on pseudo-discrete kinematics, while providing a mechanism-based description of material anisotropy and coupling behaviors uncovered by classical elasticity. An analytic micro-macro moduli correspondence procedure is also established, based on the formal analogy with the constitutive tensor of centrosymmetric planar micropolar continua. As an important result of this research, we show that distinctive chiral effects of micropolar elasticity can be reproduced by introducing a directional independent pseudo-scalar pair potential, which turns out to be analytically vanishing when the rotationally invariant part of the corresponding continuum elastic tensor is invariant to mirror reflections as well. Moreover, the proposed formulation demonstrates sensitivity to elastic bending size-effect as specific property of structured materials homogenized as micropolar continua, and related to the characteristic length of their underlying microstructure. The resulting constitutive non-locality, which plays an important role in fracture problems, is conceptually separated with respect to the intrinsic non-local character of the model related to the integral nature of its governing equations, and then does not vanish when the horizon reduces to zero. The theoretical findings and the effectiveness of the model are successfully verified through illustrative examples referred to representative cases of structured materials homogenized as micropolar continua, including length-scale dependent quasi-static crack propagation as well as the mechanism-based description of the coupling between bulk strain and micro-rotation in elastic bi-dimensional homogenized chiral lattices. • Continuum-molecular formulation for bi-dimensional micropolar elasticity. • Mechanism-based description of material anisotropy and chiral properties. • All the symmetry classes of centrosymmetric 2D micropolar elasticity are covered. • Sensitivity to bending size-effect in microstructured solids is shown. • Analogies between continuum-molecular models and periodic lattice-like materials. [ABSTRACT FROM AUTHOR]

• Three pairs of chiral binaphthyl based macrocyclic tetraphenylethylenes (TPEs) with flexible macrocycle backbones and different linkage lengths were designed and synthesized. • The homochiral helical orientations of TPEs in the crystal structures demonstrate the successful chirality transfer from chiral binaphthyl to TPE via the soft macrocycle backbone. • Obvious aggregation-induced emission (AIE) and CPL properties can be detected owing to the chiral macrocyclic architectures. • The chiral macrocycle with the longest linkage length can produce the largest aggregation-induced circularly polarized luminescence (AI-CPL) signals in films with luminescence dissymmetry factor (g lum) up to 1.9 × 10−3. Developing chiral macrocycles with intense circularly polarized luminescence (CPL) has received considerable interest. The chirality transfer in the chiral macrocycles with separated chiral sources and luminophores is crucial but rarely explored. In this paper, we designed and synthesized three pairs of chiral binaphthyl based macrocyclic tetraphenylethylenes (TPEs) with flexible macrocycle backbones and different linkage lengths. The homochiral helical orientations of TPEs in the crystal structures demonstrate the successful chirality transfer from chiral binaphthyl to TPE via the soft macrocycle backbone. Obvious aggregation-induced emission (AIE) and CPL properties can be detected owing to the chiral macrocyclic architectures. Most importantly, the chiral macrocycle with the longest linkage length can produce the largest aggregation-induced circularly polarized luminescence (AI-CPL) signals in films with luminescence dissymmetry factor (g lum) up to 1.9 × 10−3. [Display omitted] [ABSTRACT FROM AUTHOR]

Asymmetry is a common phenom among invertebrates. A consequence of this phenom is the rise of chiral forms (or enantiomorphs), which are structures that are mirror images of each other. The asymmetry can be divided into two: directional asymmetry, when only one of the enantiomorphs exists in nature, and antisymmetry, when both chiral forms exist in nature in equal frequencies, a much rarer phenom than the prior. In this paper, I describe the unknown male and redescribe the female of Isagoras paxillus (Westwood) and a new species of Isagoras Stål from the Brazilian Atlantic Forest, Isagoras sobrali sp. nov. (based on males from Rio Grande do Norte: Natal). Furthermore, I also describe the first case of antisymmetry in Phasmatodea in these two species and discuss the relevance of this finding within a morphological, behavioral, and systematic context. [ABSTRACT FROM AUTHOR]

This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers’ separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc. This is reported in the first part of the paper illustrating the features of the nano-LC. In addition, chiral resolution methods are briefly illustrated. Some chiral selectors, used in high-performance liquid chromatography have also been applied in nano-LC including cyclodextrins, glycopeptide antibiotics, modified polysaccharides etc. This is discussed in the second part of the review. Finally some examples of the applications available in literature are reported. [ABSTRACT FROM AUTHOR]

Plasmonic dimer metamaterials have been widely utilized in the study of chiral nanophotonics due to their special chiroptical properties. The chiroptical properties of simple rod-like dimer metamaterials can be intuitively described by the Born–Kuhn (BK) model, in which the coupling parameter between oscillators is commonly used as a constant. However, the BK model is limited for complex dimer metamaterials because the behavior of the oscillators is constrained by the geometry of the structure. In this paper, inspired by equivalent LC-coupled circuits, we develop the BK model to predict the chiroptical properties of the split-ring resonator (SRR) dimer metamaterials, where the coupling of oscillators depends on both the twist angle of the SRR dimers and the frequency of the incident light. Using the extended BK model, we predict that there exists a special twist angle, which will cause the chirality of the SRR dimer metamaterials to reverse. More importantly, in such specific spatial configurations, the SRR dimer metamaterials with rectangular slits not only retain the enhancement of the chiral near-field, but also limit the chiroptical far-field response because the interactions of electricity and magnetism cancel each other out. In addition, combined with simulation calculations, we find that the rectangular SRR dimer metamaterials have strong robustness within a certain range of structural regulation. Our work will be helpful for the design and optimization of optical logic elements, chiral sensor components, and coding devices. • Analytical expression describes the chirality of the split-ring dimers. • Specific twist angle of the dimers causes the chirality to reverse. • The designed dimers process robustness against geometric perturbations. [ABSTRACT FROM AUTHOR]

• Amino acid modified wood solves the disadvantage of high cost and difficult separation of chiral catalysis. • Wood natural tertiary channels are fully utilized to enhance mass flow and promote catalytic reactions. • The stable bonding of amino acids not only improves performance, but also prolongs the lifetime of the catalyst. Molecular sieve catalysts have been adopted in chiral catalytic reactions due to their high specific surface area, nano-scaled pores and effective separation, however, the problems like low utilization ratio of channels, difficult modification, long period and complex preparation, and no economic benefits reduce its widely application. In this paper, natural wood was employed as raw material to preserve the cellulose skeleton rich in poly‑hydroxyl and the multistage porous channels of nanometer, micron and millimeter by simple treatment. A low-cost, high-yield and high-selectivity chiral catalyst could be obtained from wood with chiral catalytic sites. The in situ grafting method retains the well-developed multistage pore structure of wood, enhances the mass transfer and possesses universal applicability to different aldol condensation reactions. The asymmetric reaction of cyclohexanone and p-nitrobenzaldehyde is catalyzed by grafting readily available amino acids such as threonine, with a yield of 82% and selectivity of 57%. Molecular sieve-like wood possesses the advantages of low economic cost and good catalytic performance, which provides a potential possibility to replace traditional molecular sieve catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years cardiovascular diseases were the second most common cause of death worldwide. Therefore, the consumption of cardiovascular drugs is high, which might result in an increase of them in the environment. The major source of aquatic environmental contamination is still effluents of wastewater treatment plants (WWTPs). Unfortunately removal of cardiovascular active compounds and/or their metabolites in WWTP is still unsatisfactory. Among microbial and abiotic degradation of these compounds during wastewater processes, photolysis and photodegradation of cardiovascular drugs also play an important role. New formed compounds may be more toxic or retain the properties of parent compounds. Thus the main goal of this paper was to provide a detailed and comprehensive review of used analytical methods, coupled to liquid chromatography–tandem mass spectrometry, to determine the presence of cardiovascular compounds in surface waters as well as WTTPs effluents and influents. Exhaustive preparation for mass spectrometry detection and quantitation including samples pre-treatment, and the common problem of the matrix effect are thoroughly explored in this paper. Additionally, the article provides some hints in respect of recently noted problematic issue related to the availability of specific standards for the analysis of drug’s metabolites. Furthermore, information concerning the metabolism of cardiovascular active compounds including differences in metabolism within enantiomers is described. This article also touches on the problems associated with environmental risk assessment due to the presence of cardiovasculars in the environment. The paper also tries to explain differences in concentrations among cardiovascular compounds between countries worldwide. [ABSTRACT FROM AUTHOR]

Recently, interest in supercritical fluid chromatography (SFC) has increased due to its high throughput and the development of new system improving chromatographic performances. However, most papers dealt with fundamental studies and chiral applications and only few works described validation process of SFC method. Likewise, evaporative light scattering detection (ELSD) has been widely employed in liquid chromatography but only a few recent works presented its quantitative performances hyphenated with SFC apparatus. The present paper discusses about the quantitative performances of SFC-ELSD compared to HPLC-ELSD, for the determination of plasticizers (ATBC, DEHA, DEHT and TOTM) in PVC tubing used as medical devices. After the development of HPLC-ELSD, both methods were evaluated based on the total error approach using accuracy profile. The results show that HPLC-ELSD was more precise than SFC-ELSD but lower limits of quantitation were obtained by SFC. Hence, HPLC was validated in the ±10% acceptance limits whereas SFC lacks of accuracy to quantify plasticizers. Finally, both methods were used to determine the composition of plasticized-PVC medical devices. Results demonstrated that SFC and HPLC both hyphenated with ELSD provided similar results. [ABSTRACT FROM AUTHOR]

In the present paper spaces of fifth-order tensors involved in bidimensional strain gradient elasticity are studied. As a result complete sets of matrices representing these tensors in each one of their anisotropic system are provided. This paper completes and ends some previous studies on the subject providing a complete description of the anisotropic bidimensional strain gradient elasticity. It is proved that this behavior is divided into 14 non equivalent anisotropic classes, 8 of them being isotropic for classical elasticity. The classification and matrix representations of the acoustical gyrotropic tensor are also provided, these results may find interesting applications to the study of waves propagation in dispersive micro-structured-media. [ABSTRACT FROM AUTHOR]

This paper proposes a deterministic gathering algorithm for n ≥ 5 autonomous, homogeneous, asynchronous, oblivious unit disc robots (fat robots). The robots do not have common coordinate system and chirality. A robot can sense or observe its surroundings by collecting information about the positions of all the robots. Based on this information, they compute their destinations for moving and move there. Initially, the robots are stationary and separated. Robots are assumed to be transparent but solid. The algorithm for gathering is designed in such a way that the robots do not collide. In order to avoid collision we do not allow all the robots to move at a time. A unique robot, called leader is elected to move to its destination. No other robot moves till the leader reaches its destination. When the leader reaches its destination, another leader is selected from the remaining robots. However, leader election may not be possible in an arbitrary configuration. In this paper, we characterize all geometric configurations where leader election is possible and present an algorithm for leader election in such a case. An important property of our leader election algorithm is that it is possible to elect a leader from the remaining set of robots also. [ABSTRACT FROM AUTHOR]

Modeling phenomena of small band-gap Carbon Nanotube (CNT) is analyzed in this paper. Device physics of CNT is studied and do the calculation of sub-band for zigzag CNT to model small band-gap tubes. Each carbon nanotube is illustrated as a single graphite sheet turned round into a cylindrical shape so that the arrangement is one dimensional with axial proportion. A comparison is made with the current literature to show that the proposed chirality CNT with small band-gap which performs the modeling of nano sensor. Furthermore, a sensing device is modeled and discussed in this paper. This carbon nanotube based sensing device makes it possible produce huge amount of nano chips as a disposable cartridge for diagnostic purposes. The optimum CNT is proposed in this paper to model a nano-electrode device. This research outcome shows that the importance of identification with verified uniqueness of high reliability and economical micro-fabrication for cost effectiveness. [ABSTRACT FROM AUTHOR]

The structural property of the magnetic field in flare-bearing solar active regions (ARs) is one of the key aspects for understanding and forecasting solar flares. In this paper, we make a comparative analysis on the chirality and magnetic configurations associated with two X-class two-ribbon flares happening in AR 10930 and AR 11158. The photospheric magnetic fields of the two ARs were observed by space-based instruments, and the corresponding coronal magnetic fields were calculated based on the nonlinear force-free field model. The analysis shows that the electric current in the two ARs was distributed mostly around the main polarity inversion lines (PILs) where the flares happened, and the magnetic chirality (indicated by the signs of force-free factor α) along the main PILs is opposite for the two ARs, i.e., left-handed (α < 0) for AR 10930 and right-handed (α > 0) for AR 11158. It is found that, for both the flare events, a prominent magnetic connectivity (featured by co-localized strong α and strong current density distributions) was formed along the main PIL before flare and was totally broken after flare eruption. The two branches of the broken magnetic connectivity, combined with the prominent magnetic connectivity before flare, compose the opposite magnetic configurations in the two ARs owing to their opposite chirality, i.e., Z-shaped configuration in AR 10930 with left-handed chirality and inverse Z-shaped configuration in AR 11158 with right-handed chirality. It is speculated that two-ribbon flares can be generally classified to these two magnetic configurations by chirality in the flare source regions of ARs. [ABSTRACT FROM AUTHOR]

The gathering (or multi-agent rendezvous) problem requires a set of mobile agents, arbitrarily positioned at different nodes of a network to group within finite time at the same location, not fixed in advanced. The extensive existing literature on this problem shares the same fundamental assumption: the topological structure does not change during the rendezvous or the gathering; this is true also for those investigations that consider faulty nodes. In other words, they only consider static graphs. In this paper we start the investigation of gathering in dynamic graphs , that is networks where the topology changes continuously and at unpredictable locations. We study the feasibility of gathering mobile agents, identical and without explicit communication capabilities, in a dynamic ring of anonymous nodes; the class of dynamics we consider is the classic 1-interval-connectivity ; i.e., dynamic graphs that are however connected at any point in time. We focus on the impact that factors such as chirality (i.e., a common sense of orientation) and cross detection (i.e., the ability to detect, when traversing an edge, whether some agent is traversing it in the other direction), have on the solvability of the problem; and we establish several results. We provide a complete characterization of the classes of initial configurations from which the gathering problem is solvable in presence and in absence of cross detection and of chirality. The feasibility results of the characterization are all constructive: we provide distributed algorithms that allow the agents to gather within low polynomial time. In particular, the algorithms for gathering with cross detection are time optimal. We also show that cross detection is a powerful computational element. Indeed, we prove that, without chirality, knowledge of the ring size n is strictly more powerful than knowledge of the number k of agents; on the other hand, with chirality, knowledge of n can be substituted by knowledge of k , yielding the same classes of feasible initial configurations. From our investigation it follows that, for the gathering problem, the computational obstacles created by the dynamic nature of the ring can be overcome by the presence of chirality or of cross-detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optical properties of carbon nanobelts with zigzag and armchair edges, as well as interlocked carbon nanobelts for chirality. • TPA and ECD techniques can effectively differentiate carbon nanoribbons with different boundaries, revealing their relationship and distinguishing features. • The better comprehension of carbon nanoribbons, mechanically interlocked molecules, and chirality. This paper presents a theoretical study on the optical properties of carbon nanobelts with zigzag and armchair edges, as well as interlocked carbon nanobelts for chirality. The results demonstrate that two photon absorption (TPA) and electronic circular dichroism (ECD) techniques can effectively differentiate carbon nanoribbons with different boundaries, revealing their relationship and distinguishing features. The findings from this research contribute to a better comprehension of carbon nanoribbons, mechanically interlocked molecules, and chirality. [ABSTRACT FROM AUTHOR]

A multifunctional chiral metamaterial based on the asymmetric interface condition and thermal-induced phase transition is proposed in this paper. Adding the dynamic layer to form the asymmetric interface will excite the chirality. The CD MAX can reach 0.83. Besides, the chirality state can be modified by the thermal control conductivity of VO 2. CD of metamaterials reaches 0.6 at 5.425 THz when VO 2 is insulated and switches to −0.4 after it turns to metallic. An application in double-encryption is envisaged and discussed. The proposed multifunctional chiral metamaterials provide a wide range of possible applications in chiral switching, sensing, communications, encryption, etc. • Combine asymmetric interface with vanadium oxide to achieve chirality switchable metamaterials. • Make use of the chirality exited by the asymmetric interface in the terahertz gap. • Propose an encrypted sorting method based on the characteristics of our device to show its application prospect. [ABSTRACT FROM AUTHOR]

• The metasurface achieves CD of up to 0.998 in the MIR band, which is larger than existing report. • The metasurface consists of only four GSST nanopillars and a substrate, which has significantly lower losses compared to common metal-dielectric metasurfaces. • The metasurface has two functions, circular polarization transition and CD. Moreover, we arrange the meta -atoms with different rotation angles to realize various functional metasurfaces. In this paper, an all-dielectric metasurface based on phase-change material Ge 2 Sb 2 Se 4 Te 1 (GSST) working in the mid-infrared band is designed, and combined with Pancharatnam-Berry (PB) phase to realize multifunctional metasurfaces. The metasurface can convert incident circularly polarized waves to transmitted or reflected waves of opposite chirality, regardless of GSST is in amorphous or crystalline state. Due to constructive interference and destructive interference, the metasurface obtains giant circular dichroism (CD). The maximum CD value reaches 0.997 at f = 64 THz when GSST is in amorphous state and 0.97 at f = 45 THz when GSST is in crystalline state. According to the principle of PB phase, three optical devices are realized by the rational arrangement of all-dielectric meta -atoms with different rotation angles, which are beam deflectors, lenses and vortex beam generators. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optical absorption and molecular chirality of π-conjugated MIMs are theoretically investigated. • Our findings reveal the optical excitation properties of MIMs and chirality resulting from interlocked mechanical bonds. • We propose new methods to identify interlocked mechanical bonds. This paper presents a theoretical investigation of the optical absorption and molecular chirality of π-conjugated mechanically interlocked nanocarbons, using one photon absorption (OPA) and two photon absorption (TPA) as well as electronic circular dichroism (ECD) spectra. Our findings reveal the optical excitation properties of mechanically interlocked molecules (MIMs) and chirality resulting from interlocked mechanical bonds. While OPA spectra are unable to distinguish interlocked molecules from non-interlocked molecules, we demonstrate that TPA and ECD can effectively discriminate between them, and can also differentiate [2]catenanes from [3]catenanes. Thus, we propose new methods to identify interlocked mechanical bonds. Our results provide physical insight into the optical properties and absolute configuration of π-conjugated interlocked chiral nanocarbons. [ABSTRACT FROM AUTHOR]

• Chirality results from lack of symmetry of non-superimposable objects. • There is relatively much less literature on chirality of nanomaterials than on organic molecules. • Chirality is often induced extrinsically in nanomaterials by adsorption of chiral molecules. • Many studies have shown that chirality can affect intracellular uptake, biodistribution and toxicity of many nanomaterials. • Therefore, there may be need for adequate consideration of the effects of chirality on their toxicity. Toxicity assessments are required for nanomaterials which are being used in many fields such as medicines, electronics, pesticides, clothes and construction materials. One factor that usually affects toxicity of chemicals is chirality. This paper reviews the existence of chirality in nanoparticles and critically analyses the implications of chirality on toxicological risk assessment of nanoparticles. Chirality and optical activity arise from lack of symmetry, where an object is non-superimposable on its mirror image. Optical isomers or enantiomers have similar physico-chemical properties but only differ in their optical activity and their interaction with biological systems. Chirality is not limited to organic molecules, but also exists in inorganic compounds and crystals. Studies have also shown that chirality can be bestowed onto nanoparticles by adsorption of chiral molecules, and by careful design of the crystal to expose chiral kinked and stepped surface structures. Just as chirality has been shown to affect the biological activities of conventional chemicals, nanoparticles functionalised with different enantiomers have been shown to exhibit enantioselectivity and different toxicities. However, at the moment more studies on the ligands and the conditions under which chirality occurs in NPs, as well as on the effects of NP chirality on protein adsorption kinetics and thermodynamics. Nevertheless, this cursory analysis has shown the importance of chirality on biological activity of nanoparticles. In cases where there is a potential for the existence of chirality in nanomaterials (either intrinsic or extrinsic), there may be need for adequate consideration of the effects of chirality. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we theoretically analyze the nature of chirality induced by molecular self-assembly with molecular dynamics and visualization methods. Firstly, the dynamics of molecular self-assembly of biphenylenes system are demonstrated in detail. Secondly, the molecular interactions for the assembled molecules are analyzed with the weak intermolecular forces. Thirdly, electron-hole coherence and charge transfer in optical absorption are demonstrated with a transition density matrix and charge difference density, respectively. The detailed visualized analysis of electric and magnetic transition dipole moment integrals reveals the nature of chirality of assembled molecules in electronic circular dichroism (ECD) spectroscopy. The Raman optical activity (ROA) spectra demonstrate that the chirality of assembled molecules is strongly dependent on the pre-resonance Raman spectra, based on the optical absorption and ECD spectroscopy. Our visualized analysis method can well reveal the nature and origin of chirality of molecular self-assembly. Graphical Abstract Unlabelled Image Highlights • Firstly, the dynamics of molecular self-assembly of biphenylenes system are demonstrated in detail. • Secondly, the molecular interactions for the assembled molecules are analyzed with the weak intermolecular forces. • Thirdly, electron-hole coherence and charge transfer in optical absorption are demonstrated with a transition density matrix and charge difference density, respectively. • The detailed visualized analysis of electric and magnetic transition dipole moment integrals reveals the nature of chirality of assembled molecules in ECD spectroscopy. • The ROA spectra demonstrate that the chirality of assembled molecules is strongly dependent on the pre-resonance Raman spectra. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a multi-functional polarization convertor for terahertz (THz) light composed of a bilayer wire-split-ring (WSR) structure chiral metamaterial (CMM) was proposed and investigated numerically. Simulation results indicate that when normal incident light is propagating along the – z axis direction through the proposed CMM structure, the y -polarization is converted to the left- and right-circular polarization (LCP and RCP) at 1.14 THz and 1.34 THz, respectively. Meanwhile, the x -polarization is converted to y -polarization in the frequency range of 2.19 – 2.47 THz. The further calculation results show that the proposed CMM structure can transmit a nearly pure circular polarization light with a polarization extinction ratio (PER) of over 30 dB and an orthogonal linear polarization light with a polarization conversion ratio (PCR) of over 90%. The mechanism of the polarization conversion properties is illustrated by the simulated electrical field and surface current distribution. Due to its excellent multi-functional polarization conversion properties, the proposed CMM is useful for the development of the integrated THz polarization manipulation devices. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic representation of pixelated-polarization-camera-based polarimetry system for optical rotation sensing. Highlights • A pixelated-polarization-camera-based polarimetry system was developed to detect the optical rotation of the chiral material. • The concise light path provides a convenient way, and the random error and the systematic error of the system are very low. • The sensor could achieve real-time, wide-range, high-accuracy and high-resolution detection. • The pixelated-polarization-camera-based polarimetry sensor has a higher accuracy and resolution than existing methods. Abstract Chirality is an essential consideration in the field of life sciences and pharmaceutical industry because most biomolecules and pharmaceuticals are chiral, and optical rotation measurement is a simple and efficient means for identification, purity test and content detection of chiral materials. However, there are some drawbacks in existing methods, such as small measurement range, non-real-time performance, low measurement accuracy and resolution. This paper presents a novel system to implement optical rotation measurement, and pixelated polarization cameras and Stokes parameters are employed in the system. The polarization information of linearly polarized incident light can be recorded and extracted by a pixelated polarization camera and Stokes parameters respectively. Experiments demonstrate that the proposed system has the necessary advantages for optical rotation measurement, such as real time, wide range (− 90 ° to + 90 °), high accuracy (1 × 1 0 − 4 °) and high resolution (± 6 × 1 0 − 6 °). Thus, this measurement system has great practical prospects in the hospital clinical diagnosis, chemical research, sugar production and pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Highlights • The twisting chirality configuration obviously affects the bending strength of the HTS tape. • The optimum twist angle of the HTS tape is determined. • A numerical model is built to investigate the effect of the configuration on the properties of the tape. Abstract Seeking a geometry that can withstand greater transverse loads based on the electromechanical material properties of high-temperature superconducting (HTS) tape is an effective way of improving the transport performance of HTS cables. The cabling method requires the determination of the optimum twist angle of the HTS tape for withstanding transverse loads. This paper investigates the critical current characteristics of HTS tapes under combined deformation. The limit range of the twist angle under the combined deformation is measured and the optimum twist angle of the HTS tape is determined. The results show that the twisting chirality configuration obviously affects the bending strength of the HTS tape. In the elastic range, increasing the pre-twist angle increases the bending strength of the HTS tape, thereby improving the transport performance. In addition, a numerical model is built to further investigate the effect of the twisting chirality configuration on the electromechanical properties of the HTS tape, and the experimental results are explained. The experimental and simulation results generally agree well, and calculations show that there is always a sharp change in stress at the interface of different materials. These findings explain the mechanism of the effect of the twisting chirality configuration on the mechanical behavior and critical current of the HTS tape. They also provide a reference for cabling methodologies for the HTS cable configuration. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Liquid-liquid extraction of 2,3-2-PPA enantiomers in centrifugal contactor separators is proposed. • Thermodynamics data about the physical partition coefficients and chemical equilibrium constants are obtained. • A multistage equilibrium model about the separation system is established. • Model predictions can predict the experimental process very well. • Purity and yield are significantly improved by changing the process parameters. Abstract This paper reports the process optimization of chiral extraction of 2,3-diphenylpropionic acid (2,3-2-PPA) enantiomers by experiment and simulation in centrifugal contactor separators. An efficient extraction system was obtained firstly through single-stage extraction experiments and single-stage extraction model, where sulfobutylether-β-cyclodextrin (SBE-β-CD) and 1,2-dichlorethane were selected as the optimal extractant and organic solvent, respectively. The mechanism of the extraction system was proposed and the thermodynamic constants such as physical partition coefficient and reactive equilibrium constants were obtained. Based on phase and reactive equilibrium as well as the law of mass conservation, a model describing the fractional extraction process was acquired. The process of symmetrical separation of 2,3-2-PPA enantiomers was optimized by the fractional extraction model. The optimal conditions composed of flow rate ratio (W/O) of 3.0, pH of 3.00 and SBE-β-CD concentration of 0.10 mol/L were obtained. Under this case, equal enantiomeric excess (ee eq) can reach up to 37% at 10 stages. The simulated results reveal that the minimum series for ee eq > 97% and ee eq > 99% was 78 and 102, respectively. [ABSTRACT FROM AUTHOR]

180° transverse domain walls (TDWs) in planar magnetic nanowires find important applications in advanced logic and memory devices. Controlling DW structure is important because it determines DW behaviors and is used to store digital information. This paper presents, using micromagnetic simulations, simple designs of nanowire unit that enables reliable generation of TDWs and effective control of their structures under rotating magnetic field. It is shown that a series of TDWs can be created, two per loading cycle, and external magnetic field can be programmed to control the TDW structures in terms of their polarity and chirality. These nanowire units and the corresponding magnetic field control schemes can be integrated into magnetic circuits to generate TDWs of controlled structures, facilitating the development of logic and memory devices based on DW functionalities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Developed simple, fast and robust method for separation and identification of epimers. • HRMS provides excellent detection of drugs of interest in biological matrices. • The Lux i-Cellulose-5 selector was found to be more effective for the separation. • Aqueous formic acid with acetonitrile or methanol was instrumental for the separation of the epimers. Abstract Chirality is one of the most important considerations when controlling doping. The epimeric corticosteroids dexamethasone and betamethasone are significantly potent and long-acting, and they are highly abused in equestrian sports. The scope of this study was to develop a simple and reliable analytical method for simultaneously identifying and separating regularly abused co-eluting corticosteroids in equine urine and plasma. In this paper, we present a simple and rapid method for the chiral separation and identification of epimeric mixtures of dexamethasone and betamethasone using a Thermo Q Exactive high resolution accurate mass spectrometer. The high resolution accurate mass spectrometer system provided extremely high sensitivity, enabling detection of each isomer at a very low concentration from complex biological matrices. Chromatographic separation was performed using amylose and cellulose chiral columns. Reversed phase media showed very good potential for providing a successful chiral resolution in LC-MS analysis. This study also focused on optimizing the mobile phase for elution strength, nature of the organic modifier, additives, and column temperature. [ABSTRACT FROM AUTHOR]

Abstract In this paper, an investigation was carried out to understand the mechanical elastic properties of a newly developed 3D nanocarbon structure material known as PGS (pillared graphene sheet). The effect of various parameters such as the pillared distance, the chirality, the volume fraction and the inclination angle of carbon nanotube on the elastic moduli was studied using the finite element method. The commercially available finite element software ABAQUS was utilized for the modelling and analysis of this new structure. Several different models were developed to study the effect of the various parameters mentioned earlier. Some interesting conclusions were deduced from the finite element investigation. It was found that the pillared distance, chirality and volume fraction affected the modulus significantly. The change in volume fraction impacted a bigger influence on the Young's modulus E z and shear modulus G xy. In some instances, E z was increased by approximately 40 times. In addition, the Young's modulus E z was also found to be affected by the change in the inclination angle and was shown to increase with increasing angle. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In summary, this paper describes synthesis of a new acidic catalyst to accomplish highly enantioselective Biginelli reactions. Sulfonic-functionalized hyperbranched polylysine (HBPL-SO 3 H) as a novel and efficient catalyst help synthesize a series of optically active dihydropyrimidinones via asymmetric synthesis. The reactions carried out under solvent-free conditions at 70 °C within 7 h and produced chiral dihydropyrimidinones in high yields with very good enantiomeric excess. This catalyst could be used at least 5 times without considerable decrease in activity and also induction of chirality. Simple work-up, high yield and enantiomeric excess are some of important advantages of performed reactions with this catalyst. The related organocatalyst was synthesized with 98% yield and its structure was confirmed by IR, NMR, XRD, TGA analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

The research on the interactions between plasmon and chiral materials is fundamental to the understanding of chiroptical effects and the designs of chiroptical devices. Some theories have been developed to explain the strong interactions between simple nanoparticles and chiral media, but it is difficult to apply to complicated systems. In this paper, we developed an effective method, which utilizes the chiral constitutive relations and finite element method (FEM) simulation, to investigate strong interactions between arbitrary structure and chiral media. To demonstrate the feasibility of our method, we designed a hybrid system by homogeneously coating a layer of chiral medium on achiral T-shaped gold nanoparticle (TGNP). By calculating the circular dichroism (CD) and absorption spectra of the system, we observed a large mode splitting in the CD/absorption spectra, which indicated the system achieves a strong coupling regime. Furthermore, we discovered that the CD spectra of the system can be decomposed into three curves, which are contributed by the chiral media, TGNP, and the optical chirality (OC) density. The chiroptical response of the achiral TGNP is induced by the chiral media and exhibits a strong anti-crossing behavior. The phenomenon can be explained by using the chiral Poynting's theorem and FEM. Our research has wide potential applications in chiroptical manipulation and chiral quantum optics. • An effective method is developed to investigate strong chiroptical interactions. • A large mode splitting in the CD/absorption spectra are observed. • The CD spectra of the system can be decomposed into three curves. [ABSTRACT FROM AUTHOR]

[Display omitted] • We theoretically investigate the fluorescence origin and chirality mechanism of graphene quantum dots with non-twist. • It is revealed that twist is not necessary for fluorescence; but twist is must for the chirality. • Twist can significantly enhance the intensity of chirality, demonstrated by ECD spectra. • Our results provide physical mechanism of fluorescence and chirality of graphene quantum dot influenced by geometric twist. In this paper, we theoretically investigate the fluorescence origin and chirality mechanism of graphene quantum dots with non-twist and twist geometries, respectively. It is revealed that twist is not necessary for fluorescence; but twist is must for the chirality, which can significantly enhance the intensity of chirality, demonstrated by ECD spectra. Our results provide deeper understanding on the physical mechanism of fluorescence and chirality of graphene quantum dot influenced by geometric twist. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the structural relaxation of N-acetyl-α-methylbenzylamine (Nac-MBA), a chiral organic molecule, through the study of the glass transition temperature T g and the well-known physical ageing, occuring at temperatures lower than T g . The influence of the enantiomeric excess (ee) on the structural relaxation kinetics is highlighted through standard differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC) investigations. This original work evidences that even if the enthalpy loss to reach equilibrium remains globally the same whatever the ee, the structural relaxation kinetics are clearly slowed down when ee is increased. [ABSTRACT FROM AUTHOR]

In the present paper we describe the optimization and the application of a chromatographic method suitable to get all four diastereoisomers of C24–C25 cyclopropyl dafachronic acid derivatives in sufficient amount for their biological appraisal towards the nuclear hormone receptor transcription factor DAF-12. A preliminary column screening of six anion exchange type Cinchona alkaloid-based chiral stationary phases (CSPs) allowed to identify the one with a quinine scaffold and carrying a O -9-(3,5-bis(trifluoromethyl)phenyl) moiety at C9 position as the best CSP. Few modifications of the experimental conditions revealed that a content of 18 mM acetic acid used as counterion and displacer in acetonitrile and a column temperature fixed at 35 °C were optimal for the simultaneous discrimination of all four diastereoisomers with a 1.0 mL/min flow rate. With such conditions, transoid ( S , S ) and ( R , R ) diastereoisomers were resolved with R S > 1.4. With non chiral reversed-phase columns, neither the cisoid nor the transoid diastereoisomers could be resolved. This way, ca. 1.0 mg of each stereoisomer was isolated with a diastereomeric purity >98%, suitable for the following biological tests. The indirect stereochemical assignments of the four diastereoisomers, and hence the corresponding chromatographic elution order (24 R ,25 R ) < (24 S ,25 S ) < (24 R ,25 S ) < (24 S ,25 R ) were made in an analogy manner on the basis of the resolution of fully assigned and structurally very similar ursodeoxycholic acid derivatives. As support of this indirect way of assigning the absolute configuration of the C24 and C25 chiral centre a molecular modeling procedure based on dynamic simulation was successfully applied. [ABSTRACT FROM AUTHOR]

This paper presents a new bi-material microstructural design method for chiral auxetic metamaterials. Based on the independent point-wise density interpolation (iPDI) and a bi-material model, optimal design problem of periodic unit cells is formulated using nodal density variables. The design objective is to minimize the Poisson’s ratio while satisfying the specified volume constraints of the hard and soft materials, and the effective elastic properties of the bi-material microstructure are computed by the asymptotic homogenization method under periodic boundary conditions. This topology optimization problem is solved with a gradient-based mathematical programming algorithm on the basis of the sensitivity analysis. Several numerical examples, regarding design of anisotropic, orthogonal anisotropic and isotropic bi-material microstructures of chiral auxetic metamaterials, are given to demonstrate the effectiveness of the method. It is shown that the proposed bi-material design optimization method can be used to improve the performance of chiral auxetic metamaterials through enlarging the design space. [ABSTRACT FROM AUTHOR]

Single crystals of single-wall carbon nanotubes are desired for precise analysis of the physical properties of carbon nanotubes, necessitating preparation of single-chirality enantiomers in large quantities. In this work, by investigating the effects of surfactant concentration and temperature on the enantiomer separation, we achieved large-scale single-chirality enantiomer separation for the first time using triple surfactant stepwise elution chromatography with a naturally produced dextran-based gel as the column medium. Through one-round programmed separation, milligram-scale of (11,–5) (equivalent to (5,6)) and (6,5) enantiomers were separated from CoMoCAT carbon nanotube soot. The separation yields estimated from the optical absorbance at 280 nm were 5.6% (11,−5) and 2.6% (6,5) per load of all SWCNTs, which correspond 28% and 13% per load of total (11,–5) and (6,5) enantiomers, respectively. This high yield is mainly attributed to the narrow chirality distribution and high concentrations of (11,–5) and (6,5) in CoMoCAT and the high-resolution selectivity of the triple surfactant system for two enantiomers. The high throughput is sufficient to prepare high-purity (11,–5) and (6,5) bucky papers. [ABSTRACT FROM AUTHOR]

The possibility of switching the direction of the dipole toroidal moment in ferroelectrics provides exciting opportunities for development of novel nanoscale memory and logic devices. However, a practical control of vortex chirality is rather challenging at present stage, not to mention via mechanical methods. In this paper, we performed the phase-field simulations to show that mechanical switching of vortex chirality can be achieved in ferroelectric nanoplatelet via defect engineering. After introducing a void defect in the nanoplatelet, relative stability of single-vortex state and multi-vortices state is found to be altered. Importantly, during stress-induced vortex multiplication process, the void is a favored nucleation core of new vortex; meanwhile, vortices tend to annihilate away from the void during a vortex annihilation process. As the favored regions of vortex nucleation and annihilation are not the same, a deterministic mechanical switching of vortex chirality can be achieved. The effects of temperature, shape of the nanoplatelet, void size, as well as void position, on the defect-mediated vortex switching behaviors are systematically revealed. Our study demonstrates the feasibility of vortex switching by mechanical loads and provides a route to control and develop electromechanical devices based on ferroic vortices. [ABSTRACT FROM AUTHOR]

In this paper, a kind of chiral all-dielectric metasurface is demonstrated numerically to achieve giant asymmetric transmission (AT) in fiber communication region. The incoming polarized electromagnetic wave excites magnetic and electric resonances and the resonances in AT spectrum coincide with eigen frequencies of this structure. The all dielectric metasurface shows more excellent properties compared with its metal counterpart. AT is influenced significantly by material permittivity as well as unit cell period. The concept of all-dielectric metasurface offers a new way to manipulate electromagnetic waves and the phenomenon remains effective in other frequencies. [ABSTRACT FROM AUTHOR]

Design of supramolecular organization to produce large optical activity involves multiple factors either internal as external. In this paper, we report on the synthesis, systematic study and theoretical modeling of a series of chiral polyfluorene derivatives, whereby we identify the main parameters controlling the chiroptical activity of polymer films. For each polymer, five empirical/theoretical properties were chosen, due to their effect on the chirality parameter: glass transition temperature, dissymmetry factor, molar mass, helix tightness and the inverse of interconversion energy. We introduce a radar graph exhibiting the influence of chirality metric on these five parameters and their interplay. The polygonal area in the radar graph and the chirality parameter presented a direct relationship. Such graph can provide pre-screening of polymer properties, based on both experimental measurements and theoretical considerations and help choosing the right combination of parameters, leading to a material with the best properties. [ABSTRACT FROM AUTHOR]

• The effect of the helical chirality on the local contact behavior is analyzed. • The 1D and 2D contact models are introduced to solve line and point contact forces. • The fretting wear factor of structures is calculated based on the Archard's equation. • The optimal designs of multilevel chiral helical structures are obtained by NSGA-Ⅱ. The local contact characteristics of multilevel chiral helical structures are critical, which determines the fretting wear and further affects the service life. In this paper, a theoretical model including global mechanical behaviors, local contact, and fretting wear is established. The ratio of the axial total moment to force is utilized to describe the load bearing capacity. Two kinds of models are developed for contact forces: 1D-explicit and 2D-iteration model, which are verified by the finite element method (FEM). The 1D model provides the explicit expressions of contact forces, meanwhile, the 2D model possesses the high accuracy under the short pitch. Different kinds of contact forces and the fretting wear are solved by the multilevel contact transmission law and the Archard's equation, respectively. Subsequently, the Pareto sets of multilevel chiral helical structures are obtained based on the theoretical model and the Non-dominated Sorting Genetic Algorithm-Ⅱ (NSGA-Ⅱ). Optimal designs with a strong load bearing capacity and a high fretting wear resistance are exhibited, which is useful to guide the design of multilevel chiral helical structures. [ABSTRACT FROM AUTHOR]

As the requirement of chiral compounds increases, the studies on asymmetric catalytic synthesis and separation are of interest. For these kinds of researches, identifications of chiral centers are often required. However, it's time-consuming, especially for the compounds with multiple chiral centers. Thus, a method to automatically identify chiral center based on highly selective atomic chiral index was suggested in this paper. At first, an atomic chiral index—aEAID was suggested based on molecular index EAID (one of the most highly discriminating indices). The uniqueness test of aEAID was performed by a virtual data set of 3,851,864 atoms, no degeneracy occurred. However, the uniqueness test was performed by NCI database of 3,814,521 atoms (NCI database were taken from the network), 12 pairs of degenerated atoms within 7 pairs of molecules were found. In order to improve the discriminating ability of aEAID, a distance factor was introduced into aEAID to generate a new highly selective atomic chiral index—d-aEAID. The two atomic data sets above were also used to test the uniqueness of the index—d-aEAID, and there was no degeneration. Furthermore, the two atomic indices, i.e., aEAID and d-aEAID, were applied to automatic identification of chiral centers for a total of more than 100,000 chiral compounds for three data sets (each compound possesses 1–38 chiral centers), and both atomic indices correctly identified all the chiral centers. [ABSTRACT FROM AUTHOR]

Reported herein is a chiral resolution polysulfone membrane prepared via mussel-inspired chemistry. Polysulfone membranes were modified with dopamine, which underwent in situ polymerization on the membrane substrate, and β-cyclodextrin was used as a chiral selector. The preparation conditions were optimized and the resultant membrane obtained under these conditions showed desirable water permeability (~ 24.0 L/(m 2 ·h·bar)) and surface hydrophilicity (contact angle is lower than 37.1 ± 3.4°). The polydopamine layer exhibited desirable stability in a series of aqueous solutions with pH values ranging from 4.0–6.0 or in isopropanol for less than an hour (detachment ratio was lower than 1.2%). Characterization of the surface morphology and XPS elemental analysis revealed that the membrane surface was fully coated by polydopamine and a β-cyclodextrin monolayer formed on the surface of the polydopamine coating. The grafting density of β-cyclodextrin calculated from the XPS results was ~ 11.5 mg/m 2 . The optimal pH value for the resolution of D - or L -tryptophan feed solution was 5.90 and a low concentration of the feed solution provided a high resolution efficiency. The enantiomeric excess (e.e.) value of the membrane for Trp racemic mixture achieved to ~ 3.2% with the feed solution of tryptophan racemic mixture was 5 × 10 − 5 mol/L and the operating pressure was 0.1 MPa. After 3 times of isopropanol-washed regeneration processes, the e.e. value was still stable around to ~ 3%. The mussel-inspired chemically modified membrane exhibited the same mechanical properties as the purely polysulfone-based membrane. The methods and results provided in this paper may facilitate the large-scale production of chiral resolution membranes or other chiral separation membranes with higher performance. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical properties of the R-graphynes are investigated by using molecular dynamics simulations. For this purpose, the uniaxial strain is applied on the nanosheets. The effects of R-graphyne chirality and dimension on their fracture and elastic properties are investigated. It is shown that the fracture properties of the armchair R-graphyne are approximately independent from the nanosheet sizes. However, a clear dependence is observed in the fracture properties of the zigzag R-graphyne on the nanosheet dimensions. Comparing the elastic modulus of the armchair and zigzag R-graphynes, it is shown that for the same sizes, the elastic modulus of armchair R-graphyne is approximately equal to 2.5 times of the elastic modulus of the zigzag ones. Pursuing the fracture process of R-graphynes with different chiralities, it is represented that the fracture propagates in the zigzag nanosheet with a higher velocity than the armchair ones. [ABSTRACT FROM AUTHOR]

The experimental approach combining high resolution transmission electron microscopy (HRTEM), electron diffraction (ED) and resonant Raman spectroscopy (RRS) on the same free-standing individual carbon nanotubes (CNT) is the most efficient method to determine unambiguously the intrinsic features of the Raman-active phonons. In this paper, we review the main results obtained by the approach regarding the intrinsic features of the phonons of single-walled (SWNT) and double-walled carbon nanotubes (DWNT). First, we detail the different methods to identify the structure of SWNTs and DWNTs from the analysis of their electron diffraction patterns (EDP). In the following, we remind the principal features of the Raman response of SWNTs, unambiguously index-identified by ED. A special attention is devoted to the effect of the inter-layer interaction on the frequencies of the Raman-active phonons in index-identified DWNTs. The information obtained on index-identified SWNT and DWNT allows us to propose Raman criteria, which help identifying CNT when the ED fails to propose a single assignment. The efficiency of the Raman criteria as the complement to the ED information for the index-assignment of a few SWNTs and DWNTs is shown. The same approach to index-assign a triple-walled carbon nanotube (TWNT), by combining ED and RRS information, is reported. [ABSTRACT FROM AUTHOR]