Asymmetric Divergent Synthesis of -Kaurane-, -Atisane-, -Beyerane-, -Trachylobane-, and -Gibberellane-type Diterpenoids.

A unified strategy toward asymmetric divergent syntheses of nine C8-ethano-bridged diterpenoids (candol A, powerol, sicanadiol, -candol A, atisirene, -atisan-16α-ol, 4-decarboxy-4-methyl-GA, trachinol, and -beyerane) has been developed based on late-stage transformations of common synthons having -kaurane and -trachylobane cores. The expeditious assembly of crucial advanced -kaurane- and -trachylobane-type building blocks is strategically explored through a regioselective and diastereoselective Fe-mediated hydrogen atom transfer (HAT) 6--trig cyclization of the alkene/enone and 3--trig cyclization of the alkene/ketone, showing the multi-reactivity of densely functionalized polycyclic substrates with π and π systems in HAT-initiated reactions. Following the rapid construction of five major structural skeletons (-kaurane-, -atisane-, -beyerane-, -trachylobane-, and -gibberellane-type), nine C8-ethano-bridged diterpenoids could be accessed in the longest linear 8 to 11 steps starting from readily available chiral γ-cyclogeraniol and known chiral γ-substituted cyclohexenone , in which enantioselective total syntheses of candol A (, 8 steps), powerol (, 9 steps), sicanadiol (, 10 steps), -candol A (, 8 steps), -atisan-16α-ol (, 11 steps), and trachinol (, 10 steps) are achieved for the first time.

Exosomal Vaccine Loading T Cell Epitope Peptides of SARS-CoV-2 Induces Robust CD8 T Cell Response in HLA-A Transgenic Mice.

Purpose: Current vaccines for the SARS-CoV-2 virus mainly induce neutralizing antibodies but overlook the T cell responses. This study aims to generate an exosomal vaccine carrying T cell epitope peptides of SARS-CoV-2 for the induction of CD8 T cell response.

Methods: Thirty-one peptides presented by HLA-A0201 molecule were conjugated to the DMPE-PEG-NHS molecules, and mixed with DSPE-PEG to form the peptide-PEG-lipid micelles, then fused with exosomes to generate the exosomal vaccine, followed by purification using size-exclusion chromatography and validation by Western blotting, liquid nuclear magnetic resonance (NMR) test and transmission electron microscopy.

Iron(III)-catalyzed tandem annulation of indolyl-substituted -quinone methides with ynamides for the synthesis of cyclopenta[]indoles.

The unique reactivity of indolyl-substituted -QMs as a new type of two-carbon synthon has been explored for the first time in a novel iron(III)-catalyzed tandem annulation. This (2+2) annulation/retro-4π electrocyclization/imino-Nazarov cyclization cascade reaction is characterized by an unusual structural reconstruction of indolyl-substituted -QMs, leading to an expeditious assembly of synthetically important functionalized cyclopenta[]indoles.

Seasonal variations in group leaf characteristics in species with red young leaves.

The leaves of many plants are red during particular stages of their lives, but the adaptive significance of leaf colouration is not yet clearly understood. In order to reveal whether anthocyanins play a similar role (i.e.

A magic red coat on the surface of young leaves: anthocyanins distributed in trichome layer protect Castanopsis fissa leaves from photoinhibition.

The presence of anthocyanins in young leaves plays an important role in mitigation against photodamage and allows leaves to grow and develop normally. Many studies have reported that foliar anthocyanins are distributed within the vacuoles of mesophyll cells, so we explored the novel defence style of anthocyanin-coated young leaves of Castanopsis fissa, a dominant subtropical forest tree species, via removable trichomes. Anthocyanins were distributed in C.

Reconstruction of Digital Skin Defects with the Free Wrist Crease Flap.

Background: Soft-tissue digital defects frequently need to be covered by a flap rather than a skin graft. In hand surgery, functional preservation and aesthetic appearance are often as important as procedural efficacy.

Objective: We present our clinical experience with reconstruction of digital skin defects with the free wrist crease flap.

A comparison of skin expansion and contraction between one expander and two expanders: a preliminary study.

Background: This study aimed to compare the difference between the skin expansion and contraction rates for an expanded flap with one versus two expanders.

Methods: The study cohort comprised 24 cases of two overlapping expanders and 15 cases of a single implanted expander involving 22 patients. The method of "wet-cloth sampling" was applied to measure the expanded flap area and the initial unexpanded area and to calculate the skin expansion rate.

Impact of committed individuals on vaccination behavior.

We study how the presence of committed vaccinators, a small fraction of individuals who consistently hold the vaccinating strategy and are immune to influence, impact the vaccination dynamics in well-mixed and spatially structured populations. For this purpose, we develop an epidemiological game-theoretic model of a flu-like vaccination by integrating an epidemiological process into a simple agent-based model of adaptive learning, where individuals (except for those committed ones) use anecdotal evidence to estimate costs and benefits of vaccination. We show that the committed vaccinators, acting as "steadfast role models" in the populations, can efficiently avoid the clustering of susceptible individuals and stimulate other imitators to take vaccination, hence contributing to the promotion of vaccine uptake.

Generic and rapid determination of veterinary drug residues and other contaminants in raw milk by ultra performance liquid chromatography-tandem mass spectrometry.

A generic, rapid and simple analytical method able to identify 255 veterinary drug residues and other contaminants in raw milk had been developed. The method was based on two-step simple precipitation and ultra performance liquid chromatography coupled with electrospray ionization and tandem mass spectrometry (UPLC-ESI-MS/MS) operating both in positive and negative multiple reaction mode (MRM). For most of the target analytes, the optimized pretreatment processes led to no significant interference on analysis from complicated sample matrix.

One-pot highly efficient synthesis of substituted pyrroles and N-bridgehead pyrroles by zinc-catalyzed multicomponent reaction.

A convenient zinc(II) chloride-catalyzed regioselective propargylation/amination/cycloisomerization process has been developed for the synthesis of substituted pyrrole derivatives from propargylic acetates, enoxysilanes and primary amines. Various aromatic and aliphatic propargylic acetates participate well in the reaction, providing the propargylation/amination/cycloisomerization products in good yields with complete regioselectivity. The one-pot multicomponent coupling reaction furnishes substituted pyrroles in high yields by circumventing the intermediates' isolation.