Stereoselective Nanocarbon Imides Featuring 12-fold [5]helicenes

Despite the great progress in research on chiral molecular nanocarbons containing multiple helicenes, controlling the stereoselectivity is still a major challenge, especially when attempting to increase the number of helicene moieties. Herein, a novel molecular nanocarbon imides composed of C204 skeleton and eighteen imide groups was successfully synthesized via an inside–out ring closing strategy involving repeated Suzuki–Miyaura coupling for C–C bond formation and photocyclic aromatization. Because of the presence of quad–core twelvefold [5]helicenes, there are, in theory, more than one hundred stereoisomers. However, only one pair of stereoisomers with D3 symmetry was observed. Despite the large and rigid skeleton, the (3M,3M,3M,3M)+(3P,3P,3P,3P) enantiomers were successfully separated by chiral HPLC, and the chiroptical properties were investigated by CD spectroscopy.

Effect of CoCrMo Addition on Ti6Al4V/xCoCrMo Biomedical Composites Processed by Powder Metallurgy

A detailed experimental and numerical investigation was performed on a Ti6Al4V/xCoCrMo biomedical composite for bone implant applications. The aim was to understand the effect generated by the addition of different volume fractions of CoCrMo particles on a Ti6Al4V matrix composite processed by powder metallurgy. Distribution of CoCrMo particles inside a matrix was observed by computed microtomography. Three-dimensional image analysis allowed for the deduction that the mechanism that permitted percolation within the powder mixture was the cluster formation at 30 vol.% of CoCrMo and at a coordination number of Co–Co contacts of 2.8, which confirms existing models. Densification during powder compaction was driven by larger indentations at the Ti–Co contacts for lower quantities of CoCrMo than for those reaching percolation. Sintering was studied by dilatometry tests at 1130 °C, and results indicated that solid-state sintering generated the formation of a rigid skeleton. This endured the stress generated by the eutectic reaction liquid, which filled the interparticle porosity, resulting in relative densities above 90%. Microstructure was analyzed by SEM and X-ray diffraction, and results showed a Ti6Al4V matrix surrounded by a Ti2Co eutectic phase. In addition, the hardness of composites increased up to three times compared to the Ti6Al4V alloy. It was concluded that the best properties were obtained from 20 vol.% of CoCrMo.

Torsional Stiffness Improvement of a Soft Pneumatic Finger Using Embedded Skeleton

Silicone-based pneumatic actuators are among the most widely used soft actuators in adaptable fingers. However, due to the soft nature of silicone, the performance of these fingers is highly affected by the low torsional stiffness, which may cause failure in grasping and manipulation. To address this problem, a compact design is proposed by embedding a rigid skeleton into a soft pneumatic finger. A finite element approach with an analytical model is used to evaluate the performance of the fingers both with and without the skeleton. Then, a series of experiments is performed to study the bending motion and rigidity of the fingers. The results reveal that the skeleton increases the torsional stiffness of the finger up to 300%. Furthermore, the consistency with the experimental data indicates the good precision of the proposed modeling method. Finally, a two-finger hand is designed to evaluate the performance of the reinforced finger in reality. The grasp experiments illustrate that the hybrid finger with the skeleton is highly adaptable and can successfully grasp and manipulate heavy objects. Thus, a potential approach is proposed to improve the torsional stiffness of silicone-based pneumatic fingers while maintaining adaptability.

Ellagic acid: A potent glyoxalase-I inhibitor with a unique scaffold

The glyoxalase system, particularly glyoxalase-I (GLO-I), has been approved as a potential target for cancer treatment. In this study, a set of structurally diverse polyphenolic natural compounds were investigated as potential GLO-I inhibitors. Ellagic acid was found, computationally and experimentally, to be the most potent GLO-I inhibitor among the tested compounds which showed an IC50 of 0.71 mmol L−1. Its binding to the GLO-I active site seemed to be mainly driven by ionic interaction via its ionized hydroxyl groups with the central Zn ion and Lys156, along with other numerous hydrogen bonding and hydrophobic interactions. Due to its unique and rigid skeleton, it can be utilized to search for other novel and potent GLO-I inhibitors via computational approaches such as pharmacophore modeling and similarity search methods. Moreover, an inspection of the docked poses of the tested compounds showed that chlorogenic acid and dihydrocaffeic acid could be considered as lead compounds worthy of further optimization.

Pose Measurement for Unmanned Aerial Vehicle Based on Rigid Skeleton

Pose measurement is a necessary technology for UAV navigation. Accurate pose measurement is the most important guarantee for a UAV stable flight. UAV pose measurement methods mostly use image matching with aircraft models or 2D points corresponding with 3D points. These methods will lead to pose measurement errors due to inaccurate contour and key feature point extraction. In order to solve these problems, a pose measurement method based on the structural characteristics of aircraft rigid skeleton is proposed in this paper. The depth information is introduced to guide and label the 2D feature points to eliminate the feature mismatch and segment the region. The space points obtained from the marked feature points fit the space linear equation of the rigid skeleton, and the UAV attitude is calculated by combining with the geometric model. This method does not need cooperative identification of the aircraft model, and can stably measure the position and attitude of short-range UAV in various environments. The effectiveness and reliability of the proposed method are verified by experiments on a visual simulation platform. The method proposed can prevent aircraft collision and ensure the safety of UAV navigation in autonomous refueling or formation flight.

Atropisomerism in Styrene: Synthesis, Stability, and Applications

Atropisomeric styrenes are a class of optically active compounds, the chirality of which results from restricted rotation of the C(vinyl)–C(aryl) single bond. In comparison with biaryl atropisomers, the less rigid skeleton of styrenes usually leads them to have lower rotational barriers. Although it has been overlooked for a long time, scientists have paid attention to this class of unique molecules in recent years and have developed many methods for the preparation of optically active atropisomeric styrenes. In this article, we review the development of the concept of atropisomeric styrenes, along with their isolation, asymmetric synthesis, and synthetic applications.1 Introduction2 The Concept of Styrene Atropisomerism3 Early Research: Separation of Optically Active Styrenes4 Synthesis of Optically Active Styrenes5 Stability of the Chirality of Atropisomeric Styrenes6 Outlook

Arm waving in stylophoran echinoderms: three-dimensional mobility analysis illuminates cornute locomotion

The locomotion strategies of fossil invertebrates are typically interpreted on the basis of morphological descriptions. However, it has been shown that homologous structures with disparate morphologies in extant invertebrates do not necessarily correlate with differences in their locomotory capability. Here, we present a new methodology for analysing locomotion in fossil invertebrates with a rigid skeleton through an investigation of a cornute stylophoran, an extinct fossil echinoderm with enigmatic morphology that has made its mode of locomotion difficult to reconstruct. We determined the range of motion of a stylophoran arm based on digitized three-dimensional morphology of an early Ordovician form, Phyllocystis crassimarginata . Our analysis showed that efficient arm-forward epifaunal locomotion based on dorsoventral movements, as previously hypothesized for cornute stylophorans, was not possible for this taxon; locomotion driven primarily by lateral movement of the proximal aulacophore was more likely. Three-dimensional digital modelling provides an objective and rigorous methodology for illuminating the movement capabilities and locomotion strategies of fossil invertebrates.

Comparative proteomics of octocoral and scleractinian skeletomes and the evolution of coral calcification

Corals are ecosystem engineers of the coral reefs, one of the most biodiverse but severely threatened marine ecosystems. The ability of corals to form the three dimensional structure of reefs depends on the precipitation of calcium carbonate under biologically control. However, the exact mechanisms underlying this biologically controlled biomineralization remain to be fully unelucidated, for example whether corals employ a different molecular machinery for the deposition of different calcium carbonate (CaCO3) polymorphs (i.e., aragonite or calcite). Here we used tandem mass spectrometry (MS/MS) to compare skeletogenic proteins, i.e., the proteins occluded in the skeleton of three octocoral and one scleractinian species: Tubipora musica and Sinularia cf. cruciata, both forming calcite sclerites, the blue coral Heliopora coerulea with an aragonitic rigid skeleton, and the scleractinian aragonitic Montipora digitata. We observed extremely low overlap between aragonitic and calcitic species, while a core set of proteins is shared between octocorals producing calcite sclerites. However, the same carbonic anhydrase (CruCA4) is employed for the formation of skeletons of both polymorphs. Similarities could also be observed between octocorals and scleractinians, including the presence of a galaxin-like protein. Additionally, as in scleractinians, some octocoral skeletogenic proteins, such as acidic proteins and scleritin, appear to have been secondarily co-opted for calcification and likely derive from proteins playing different extracellular functions. In H. coerulea, co-option was characterized by aspartic acid-enrichment of proteins. This work represents the first attempt to identify the molecular basis underlying coral skeleton polymorph diversity, providing several new research targets and enabling both future functional and evolutionary studies aimed at elucidating the origin and evolution of biomineralization in corals.

Torsional Stiffness Improvement of a Soft Pneumatic Finger Using Embedded Skeleton

Silicone-based pneumatic actuators are among the most widely used soft actuators in adaptable fingers. However, due to the soft nature of silicone, the performance of these fingers is highly affected by the low torsional stiffness, which may cause failure in grasping and manipulation. To address this problem, a compact design is proposed by embedding a rigid skeleton into a soft pneumatic finger. A finite element approach with an analysical model is used to evaluate the performance of the fingers both with and without the skeleton. Then, a series of experiments is performed to study the bending motion and rigidity of the fingers. The results reveal that the skeleton increases the torsional stiffness of the finger up to 300%. Furthermore, the consistency with the experimental data indicates the good precision of the proposed modeling method. Finally, a two-finger hand is designed to evaluate the performance of the reinforced finger in reality. The grasp experiments illustrate that the hybrid finger with the skeleton is highly adaptable and can successfully grasp and manipulate heavy objects. Thus, a potential approach is proposed to improve the torsional stiffness of silicone-based pneumatic fingers while maintaining adaptability.