Taxodin A, a Cytotoxic C30 Terpenoid from Taxodium mucronatum with a Unique Skeleton.

Taxodin A (1), a unique C30 terpenoid featuring an unprecedented skeleton composed of an abietane-type diterpene and a menthane-type monoterpene, was obtained from the leaves and branches of Taxodium mucronatum. The structure and absolute configuration of compound 1 was unequivocally established by the combination of extensive spectroscopic analyses and X-ray single-crystal diffraction analysis. Compound 1 exhibited potent cytotoxic activities against A549, SMMC-7721, MDA-MB-231, and SW480 cell lines with IC50 values of 15.35±0.73, 8.49±0.35, 17.53±0.79, 18.93±0.60 µM, respectively.

Femoral Neck System vs. four cannulated screws in the treatment of Pauwels III femoral neck fracture.

OBJECTIVE: To compare the clinical efficacy of the Femoral Neck System (FNS) vs. four cannulated screws in Pauwels III femoral neck fractures. METHODS: This retrospective study included patients with newly occurred type Pauwels III femoral neck fracture treated at author' Hospital of between January 2017 and February 2021. The patients received FNS (n = 27) or four cannulated screws (control group, n = 31). The operation time, blood loss, fracture healing time, incidence of complications (such as short femoral neck, necrosis of femoral head, nonunion of fracture, and failure of internal fixation withdrawal), and hip Harris score at the last follow-up were analyzed. RESULTS: The operation time, blood loss, and fracture healing time were not significantly different between the two groups (all P > 0.05). In the FNS group, three and one patients were with femoral neck shortening and femoral head necrosis, respectively, while no fracture nonunion or failure of internal fixation withdrawal occurred. In the control group, seven, two, one, and two patients were with femoral neck shortening, femoral head necrosis, nonunion, and internal fixation failure, respectively. The cumulative complication incidence was 14.8% and 38.7% in the FNS and control groups (P = 0.042). The excellent and good rates of the hip Harris score at the last follow-up were 92.6% and 71.0% in the FNS and control groups, respectively (P = 0.036). CONCLUSION: The study suggested that the clinical efficacy of FNS was better than internal fixation using four cannulated screws in treating Pauwels III type femoral neck fracture.

Studying the effects of carbon nanotube contents on stretch-induced crystallization behavior of polyethylene/carbon nanotube nanocomposites using molecular dynamics simulations.

In the present work, we used molecular dynamics simulations to study the effects of carbon nanotube (CNT) contents on stretch-induced crystallization behavior in CNT filled polyethylene systems. During high-temperature stretching, the stretching is responsible for the orientation of CNTs, which then facilitates segment orientation and conformational transition from the gauche-conformation into the trans-conformation in interfacial regions. The systems with higher CNT contents have a higher degree of orientation and higher contents of trans-conformation during stretching, resulting in the formation of more precursors. During subsequent crystallization, the initial crystallization rate increases with the increase of the CNT content due to the increase in precursor contents in interfacial regions. However, after the CNT content exceeds a certain value, a filler network would be formed by CNTs, which can restrict chain movements and then lead to a decrease in the overall crystallization rate in the systems with high CNT contents.

Vibsane-Type Diterpenoids: Structures, Derivatives, Bioactivities, and Synthesis.

Vibsane-type diterpenoids isolated from the genus Viburnum, are rare 6-11 membered ring polysubstituted macrocyclic diterpenoids. Since the first report of vibsane-type diterpenoids from V. odoratissimum in 1980, they have attracted the attention of scientists due to their complex structures, excellent biological activities, and great synthetic challenges. Recently, there are some notable research achievements on the discovery, synthesis, structural modification, and pharmacological mechanism of vibsane-type diterpenoids. Therefore, we will focus on these aspects to review important achievements of vibsane diterpenoids between 1980-2021.

Design and fabrication of a sensitive electrochemical sensor for uranyl ion monitoring in natural waters based on poly (brilliant cresyl blue).

New insights are proposed into enhancing detection of uranyl ions (UO22+) by electropolymerization brilliant cresyl blue-modified glassy carbon electrode (PBCB/GCE). The mercury-free PBCB/GCE sensor was applied to determine UO22+ in water samples by differential pulse adsorptive stripping voltammetry (DPAdSV). The unique combination of the PBCB/GCE and DPAdSV significantly improves sensitivity due to the polymer of high electroactive area and fast electron transfer rate. The DPAdSV current using a 3 mm diameter PBCB/GCE was proportional to the UO22+ concentration in the range 2.0-90.0 µg·L-1 (- 0.113 V vs. SCE) with a detection limit of 0.650 µg·L-1, RSD = 3.1% (n = 10), and 4.5% reproducibility. In addition, the sensitivity for UO22+ determination was further improved at using an 1 mm diameter PBCB/GCE, which enhances the efficiency of UO22+ deposition due to its higher current density. The 1 mm diameter PBCB/GCE based on DPAdSV technique could be used to determine uranyl ions in the concentration range 0.20-2.0 µg·L-1 (- 0.113 V vs. SCE) with a detection limit of 0.067 µg·L-1, RSD = 5.7 % (n = 10) and 5.4% reproducibility. Hence, the PBCB/GCE is a suitable candidate to substitute the mercury electrode. Graphical abstract.

Multilevel Chirality Transfer from Amino Acid Derivatives to Circularly Polarized Luminescence-Active Nanoparticles in Aqueous Medium.

Chirality at different levels is widely observed in nature, but the clue to connect it all together, and the way chirality transfers among different levels are still obscure. Herein, a l-/d-lysine-based self-assembly system was constructed, in which two-step chirality transfer among three different levels was observed in aqueous solution. The chirality originated from the point chirality of amino acid derivatives l-/d-PyLys hydrochloride, and was transferred to the planar conformational chirality of water-soluble pillar[5]arene pR-/pS-WP5. Then, with the aid of pR-/pS-WP5, nanoparticles were formed that exhibited L-/R-handed circularly polarized luminescence with a dissymmetry factor of up to ±0.001, arising from pyrene chiral excimers. This multilevel chirality transfer not only provides a perspective to trace potential clues, and to pursue certain ways by which the chirality transfers, but also offers a strategy to create controllable CPL emission in aqueous media.

Molecular simulation of polymer crystallization under chain and space confinement.

Polymer crystallization under chain and space confinements is studied by Monte Carlo simulation. The simulation results show that the crystallinity and melting temperature of confined systems increase with the increase of free chain content. Furthermore, the crystallinity and melting temperature of confined systems with larger lateral size are higher than those with smaller lateral size. These findings are in good agreement with the conclusions obtained in some experiments. An important phenomenon that cannot be observed in experiments has been confirmed, that is, the tethering point can be used as the nucleation site. For the confined polymer system with the lateral size of 8 lattice points, with the increase of free chain content, the surface free energy of the nuclei and the diffusion activation energy of the chains decrease due to the combined effects of chain conformation size and chain movement ability, which leads to the enhancement of the nucleation ability of polymers. However, for the confined polymer system with lateral size of 12 lattice points, with the increase of free chain content, the nucleation sites decrease and the critical free energy barrier increases, which are not conducive to nucleation. Moreover, the existence of interfacial interactions can also significantly change the crystallization of confined polymers. Our results indicate the crystallization kinetics of the confined polymer from a microscopic point of view.

Three-Dimensional Finite Element Analysis and Biomechanical Analysis of Midfoot von Mises Stress Levels in Flatfoot, Clubfoot, and Lisfranc Joint Injury.

BACKGROUND Midfoot deformity and injury can affect the internal pressure distribution of the foot. This study aimed to use 3D finite element and biomechanical analyses of midfoot von Mises stress levels in flatfoot, clubfoot, and Lisfranc joint injury. MATERIAL AND METHODS Normal feet, flatfeet, clubfeet (30 individuals each), and Lisfranc injuries (50 individuals) were reconstructed by CT, and 3D finite element models were established by ABAQUS. Spring element was used to simulate the plantar fascia and ligaments and set hyperelastic coefficients in encapsulated bone and ligaments. The stance phase was simulated by applying 350 N on the top of the talus. The von Mises stress of the feet and ankle was visualized and analyzed. RESULTS The von Mises stress on healthy feet was higher in the lateral metatarsal and ankle bones than in the medial metatarsal bone. Among the flatfoot group, the stress on the metatarsals, talus, and navicular bones was significantly increased compared with that on healthy feet. Among patients with clubfeet, stress was mainly concentrated on the talus, and stress on the lateral metatarsal and navicular bones was significantly lower. The von Mises stress on the fractured bone was decreased, and the stress on the bone adjacent to the fractured bone was higher in Lisfranc injury. During bone dislocation alone or fracture accompanied by dislocation, the von Mises stress of the dislocated bone tended to be constant or increased. CONCLUSIONS Prediction of von Mises stress distribution may be used clinically to evaluate the effects of deformity and injury on changes in structure and internal pressure distribution on the midfoot.

Monoterpene Indole Alkaloids with Cav3.1 T-Type Calcium Channel Inhibitory Activity from Catharanthus roseus.

Catharanthus roseus is a well-known traditional herbal medicine for the treatment of cancer, hypertension, scald, and sore in China. Phytochemical investigation on the twigs and leaves of this species led to the isolation of two new monoterpene indole alkaloids, catharanosines A (1) and B (2), and six known analogues (3-8). Structures of 1 and 2 were established by 1H-, 13C- and 2D-NMR, and HREIMS data. The absolute configuration of 1 was confirmed by single-crystal X-ray diffraction analysis. Compound 2 represented an unprecedented aspidosperma-type alkaloid with a 2-piperidinyl moiety at C-10. Compounds 6-8 exhibited remarkable Cav3.1 low voltage-gated calcium channel (LVGCC) inhibitory activity with IC50 values of 11.83 ± 1.02, 14.3 ± 1.20, and 14.54 ± 0.99 µM, respectively.

Ultra-compact hybrid plasmonic mode convertor based on unidirectional eigenmode expansion.

An ultra-compact hybrid plasmonic mode convertor is demonstrated based on a hybrid plasmonic slot waveguide structure. Benefiting from the unidirectional eigenmode expansion approach, a mode-interference-based ${{\rm TE}_{00}}$TE00-to-${{\rm TM}_{01}}$TM01 mode convertor is realized for the first time, to the best of our knowledge, with an ultra-compact footprint of only ${2}.{33} \times {7}\,\,\unicode{x00B5} {{\rm m}^2}$2.33×7µm2. At the wavelength of 1550 nm, the insertion loss is below 2.34 dB, and the extinction ratio is 25.6 dB with mode conversion purity as high as 94.6%. The extinction ratio is over 15.5 dB for the entire C-band with a bandwidth of extinction ratio above 10 dB larger than 110 nm. The transmissivity of the crosstalk ${{\rm TE}_{10}}$TE10 and ${{\rm TE}_{02}}$TE02 at 1550 nm is $ - {16.1}$-16.1 and $ - {22.7}\,\,{\rm dB}$-22.7dB, respectively.