Rhodium-Catalyzed Asymmetric C-H Functionalization Reactions.

This review summarizes the advancements in rhodium-catalyzed asymmetric C-H functionalization reactions during the last two decades. Parallel to the rapidly developed palladium catalysis, rhodium catalysis has attracted extensive attention because of its unique reactivity and selectivity in asymmetric C-H functionalization reactions. In recent years, Rh-catalyzed asymmetric C-H functionalization reactions have been significantly developed in many respects, including catalyst design, reaction development, mechanistic investigation, and application in the synthesis of complex functional molecules. This review presents an explicit outline of catalysts and ligands, mechanism, the scope of coupling reagents, and applications.

FOXA1 regulates ribosomal RNA transcription in prostate cancer.

BACKGROUND: Ribosome biogenesis is excessively activated in tumor cells, yet it is little known whether oncogenic transcription factors (TFs) are involved in the ribosomal RNA (rRNA) transactivation. METHODS: Nucleolar proteomics data and large-scale immunofluorescence were re-analyzed to jointly identify the proteins localized at nucleolus. RNA-Seq data of five prostate cancer (PCa) cohorts were combined and integrated with multi-dimensional data to define the upregulated nucleolar TFs in PCa tissues. Then, ChIP-Seq data of PCa cell lines and two PCa clinical cohorts were re-analyzed to reveal the TF binding patterns at ribosomal DNA (rDNA) repeats. The TF binding at rDNA was validated by ChIP-qPCR. The effect of the TF on rRNA transcription was determined by rDNA luciferase reporter, nascent RNA synthesis, and global protein translation assays. RESULTS: In this study, we reveal the role of oncogenic TF FOXA1 in regulating rRNA transcription within nucleolar organization regions. By analyzing human TFs in prostate cancer clinical datasets and nucleolar proteomics data, we identified that FOXA1 is partially localized in the nucleolus and correlated with global protein translation. Our extensive FOXA1 ChIP-Seq analysis provides robust evidence of FOXA1 binding across rDNA repeats in prostate cancer cell lines, primary tumors, and castration-resistant variants. Notably, FOXA1 occupancy at rDNA repeats correlates with histone modifications associated with active transcription, namely H3K27ac and H3K4me3. Reducing FOXA1 expression results in decreased transactivation at rDNA, subsequently diminishing global protein synthesis. CONCLUSIONS: Our results suggest FOXA1 regulates aberrant ribosome biogenesis downstream of oncogenic signaling in prostate cancer.

The F-box protein ZmFBL41 negatively regulates disease resistance to Rhizoctonia solani by degrading the abscisic acid synthase ZmNCED6 in maize.

KEY MESSAGE: The maize F-box protein ZmFBL41 targets abscisic acid synthase 9-cis-epoxycarotenoid dioxygenase 6 for degradation, and this regulatory module is exploited by Rhizoctonia solani to promote infection. F-box proteins are crucial regulators of plant growth, development, and responses to abiotic and biotic stresses. Previous research identified the F-box gene ZmFBL41 as a negative regulator of maize (Zea mays) defenses against Rhizoctonia solani. However, the precise mechanisms by which F-box proteins mediate resistance to R. solani remain poorly understood. In this study, we show that ZmFBL41 interacts with an abscisic acid (ABA) synthase, 9-cis-epoxycarotenoid dioxygenase 6 (ZmNCED6), promoting its degradation via the ubiquitination pathway. We discovered that the ectopic overexpression of ZmNCED6 in rice (Oryza sativa) inhibited R. solani infection by activating stomatal closure, callose deposition, and jasmonic acid (JA) biosynthesis, indicating that ZmNCED6 enhances plant immunity against R. solani. Natural variation at ZmFBL41 across different maize haplotypes did not affect the ZmFBL41-ZmNCED6 interaction. These findings suggest that ZmFBL41 targets ZmNCED6 for degradation, leading to a decrease in ABA levels in maize, in turn, inhibiting ABA-mediated disease resistance pathways, such as stomatal closure, callose deposition, and JA biosynthesis, ultimately facilitating R. solani infection.

Palladium-Based Dyotropic Rearrangement Enables A Triple Functionalization of Gem-Disubstituted Alkenes: An Unusual Fluorolactonization Reaction.

We report in this paper a Pd(II)-catalyzed migratory gem-fluorolactonization of ene-carboxylic acids. Reaction of 4-methylenealkanoic acid derivatives with Selectfluor in the presence of Pd(OAc)2 (1.0 mol %) at room temperature affords fluorolactones in good to excellent yields. 2-(2-Methylenecycloalkanyl)acetic acids are transformed to bridged fluorolactones under identical conditions. One C-C, one C-O and one tertiary C-F bond were generated along the gem-disubstituted carbon-carbon double bond in this operationally simple transformation. Trapping experiments indicates that the reaction is initiated by a 5-exo-trig oxypalladation followed by Pd oxidation, regioselective ring-enlarging 1,2-alkyl/Pd(IV) dyotropic rearrangement and C-F bond forming reductive elimination cascade. Post-transformations of these fluorolactones taking advantage of the electrophilicity of the 1-fluoroalkylcarboxylate function are also documented.

Co-expression of transcription factors ZmC1 and ZmR2 establishes an efficient and accurate haploid embryo identification system in maize.

Because of their high efficiency during chromosome doubling, immature haploid maize (Zea mays L.) embryos are useful for doubled haploid production. The R1-nj marker is commonly used in doubled haploid breeding and has improved the efficiency of haploid identification. However, its effectiveness is limited by genetic background and environmental factors. We addressed this technical challenge by developing an efficient and accurate haploid embryo identification marker through co-expression of two transcription factor genes (ZmC1 and ZmR2) driven by the embryo-aleurone-specific bidirectional promoter PZmBD1 ; these factors can activate anthocyanin biosynthesis in the embryo and aleurone layer during early seed development. We developed a new haploid inducer, Maize Anthocyanin Gene InduCer 1 (MAGIC1), by introducing the transgenes into the haploid inducer line CAU6. MAGIC1 could identify haploids at 12 days after pollination, which is nine days earlier than CAU6. Importantly, MAGIC1 increased haploid identification accuracy to 99.1%, compared with 88.3% for CAU6. In addition, MAGIC1 could effectively overcome the inhibition of anthocyanin synthesis in some germplasms. Furthermore, an upgraded anthocyanin marker was developed from ZmC1 and ZmR2 to generate MAGIC2, which could identify haploids from diploids due to differential anthocyanin accumulation in immature embryos, coleoptiles, sheaths, roots, leaves, and dry seeds. This haploid identification system is more efficient and accurate than the conventional R1-nj-based method, and it simplifies the haploid identification process. Therefore, this system provides technical support for large-scale doubled haploid line production.

ZmCOI2a and ZmCOI2b redundantly regulate anther dehiscence and gametophytic male fertility in maize.

In higher plants, the generation and release of viable pollen from anthers is vital for double fertilization and the initiation of seed development. Thus, the characterization of genes related to pollen development and anther dehiscence in plants is of great significance. The F-box protein COI1 plays a crucial role in the jasmonate (JA) signaling pathway and interacts with many JAZ family proteins in the presence of jasmonoyl-isoleucine (JA-Ile) or coronatine (COR). The mutation of AtCOI1 in Arabidopsis leads to defective anther dehiscence and male sterility (MS), although COI has not been shown to affect fertility in Zea mays (maize). Here we identified two genes, ZmCOI2a and ZmCOI2b, that redundantly regulate gametophytic male fertility. Both ZmCOI2a and ZmCOI2b are highly homologous and constitutively expressed in all tissues tested. Subcellular localization revealed that ZmCOI2a and ZmCOI2b were located in the nucleus. The coi2a coi2b double mutant, generated by CRISPR/Cas9, had non-dehiscent anthers, delayed anther development and MS. In addition, coi2a coi2b male gametes could not be transmitted to the next generation because of severe defects in pollen germination. The JA content of coi2a coi2b anthers was unaltered compared with those of the wild type, and the exogenous application of JA could not rescue the fertility defects of coi2a coi2b. Transcriptome analysis showed that the expression of genes involving the JA signaling transduction pathway, including ZmJAZ3, ZmJAZ4, ZmJAZ5 and ZmJAZ15, was affected in coi2a coi2b. However, yeast two-hybrid assays showed that ZmJAZs interacted with ZmCOI1s, but not with ZmCOI2s. In conclusion, ZmCOI2a and ZmCOI2b redundantly regulate anther dehiscence and gametophytic male fertility in maize.

Explicit Mechanism of Rh(I)-Catalyzed Asymmetric C-H Arylation and Facile Synthesis of Planar Chiral Ferrocenophanes.

Mechanism-guided reaction development is a well-appreciated research paradigm in chemistry since the merging of mechanistic knowledge would accelerate the discovery of new synthetic methods. Low-valent transition metals such as Pd(0)- and Rh(I)-catalyzed C-H arylation with aryl (pseudo)halides is among the enabling reactions for the exclusive cross-coupling of two different aryl partners. However, different from the situation of Pd(0)-catalysis, the mechanism of Rh(I)-catalyzed C-H arylation is underexplored. The sequence of the elementary steps of aryl C-H activation and oxidative addition of aryl (pseudo)halides remains unclear. Herein, we report comprehensive experimental and computational studies toward explicit mechanistic understandings of Rh(I)-catalyzed intermolecular asymmetric C-H arylation between 2-pyridinylferrocenes and aryl bromides. The identification of each elementary step in the catalytic cycle and the structural characterization of the key intermediates and transition states allow the rational design and development of challenging intramolecular reactions. The successful realization of this reaction mode set the foundation for the facile synthesis of planar chiral [m]ferrocenophanes (m = 6-8), a class of rarely explored target molecules with strained structures and intriguing molecular topology.

Fabrication of a Cation Exchange Membrane with Largely Reduced Anion Permeability for Advanced Aqueous K-ion Battery in an Alkaline-Neutral Electrolyte Decoupling System.

Herein, an efficient method to prepare sulfonated polyether ether ketone (SPEEK) based cation exchange membranes (CEMs) is developed, where polyethersulfone (PES) is used as an additive. The optimized membrane of 30 wt.%PES/SPEEK-M exhibits a rather low anion permeability and a high ionic conductivity of 9.52 mS cm-1 together with low volume swelling in water. Meanwhile, tensile strength of the membrane is as high as 31.4 MPa with a tensile strain of 162%. As separators for aqueous K-ion batteries (AKIBs) with decoupled gel electrolytes (Zn anode in alkaline and Prussian blue (FeHCF) cathode in neutral). Discharge voltage of the AKIB can reach 2.3 V. Meanwhile, Zn dendrites can be effectively suppressed in the gel anolyte. Specific capacities of the FeHCF cathode are 116.7 mAh g-1 at 0.3 A g-1 (close to its theoretical value), and 95.0 mAh g-1 at 1.0 A g-1 , indicating good rate performance. Capacity retention of the cathode is as high as 91.2% after 1000 cycles' cycling owing to the well remained neutral environment of the catholyte. There is almost no pH change for the catholyte after cycling, indicating good anion-blocking or cation-selecting ability of the 30 wt.%PES/SPEEK-M, much better than other membranes.

The RUBY reporter enables efficient haploid identification in maize and tomato.

In vivo haploid induction has been extended from maize to monocotyledonous plants like rice, wheat, millet and dicotyledonous plants such as tomato, rapeseed, tobacco and cabbage. Accurate identification of haploids is a crucial step of doubled haploid technology, where a useful identification marker is very pivotal. R1-nj is an extensively used visual marker for haploid identification in maize. RFP and eGFP have been shown to be feasible in identifying haploid. However, these methods are either limited to specific species, or require specific equipment. It still lacks an efficient visual marker that is practical across different crop species. In this study, we introduced the RUBY reporter, a betalain biosynthesis system, into maize and tomato haploid inducers as a new marker for haploid identification. Results showed that expression of RUBY could result in deep betalain pigmentation in maize embryos as early as 10 days after pollination, and enabled 100% accuracy of immature haploid embryo identification. Further investigation in tomato revealed that the new marker led to deep red pigmentation in radicles and haploids can be identified easily and accurately. The results demonstrated that the RUBY reporter is a background-independent and efficient marker for haploid identification and would be promising in doubled haploid breeding across different crop species.

Maize Interveinal Chlorosis 1 links the Yang Cycle and Fe homeostasis through Nicotianamine biosynthesis.

The Yang cycle is involved in many essential metabolic pathways in plant growth and development. As extended products of the Yang cycle, the function and regulation network of ethylene and polyamines are well characterized. Nicotianamine (NA) is also a product of this cycle and works as a key metal chelator for iron (Fe) homeostasis in plants. However, interactions between the Yang cycle and NA biosynthesis remain unclear. Here, we cloned maize interveinal chlorosis 1 (mic1), encoding a 5'-methylthioadenosine nucleosidase (MTN), that is essential for 5'-methylthioadenosine (MTA) salvage and NA biosynthesis in maize (Zea mays). A single base G-A transition in the fourth exon of mic1 causes a Gly to Asp change, resulting in increased MTA, reduced Fe distribution, and growth retardation of seedlings. Knockout of ZmMIC1 but not its paralog ZmMTN2 by CRISPR/Cas9 causes interveinal chlorosis, indicating ZmMIC1 is mainly responsible for MTN activity in maize. Transcriptome analysis showed a typical response of Fe deficiency. However, metabolic analysis revealed dramatically reduced NA content in mic1, suggesting NA biosynthesis was impaired in the mutant. Exogenous application of NA transiently reversed the interveinal chlorosis phenotype of mic1 seedlings. Moreover, the mic1 mutant overexpressing a NA synthase gene not only recovered from interveinal chlorosis and growth retardation but was also fertile. These findings provide a link between the Yang cycle and NA biosynthesis, which highlights an aspect of Fe homeostasis regulation in maize.

Network meta-analysis on efficacy and safety of different biologics for ulcerative colitis.

BACKGROUND: Therapeutic options for ulcerative colitis (UC) have increased since the introduction of biologics a few decades ago. Due to the wide range of biologics available, physicians have difficulty in selecting biologics and do not know how to balance the best drug between clinical efficacy and safety. This study aimed to compare the efficacy and safety of biologics in treating ulcerative colitis. METHODS: In this study, eight electronic databases (PubMed, Web of Science, Cochrane, Embase, Sinomed, China National Knowledge Infrastructure, Chongqing VIP Information, and WanFang Data) were searched to collect eligible studies without language restrictions. Retrieved 1 June 2023, from inception. All articles included in the mesh analysis are randomised controlled trials (RCTs). The inclusion of drugs for each outcome was ranked using a curved surface under cumulative ranking (SUCRA). Higher SUCRA scores were associated with better outcomes, whereas lower SUCRA scores were associated with better safety. This study has registered with PROSPERO, CRD42023389483. RESULTS: Induction Therapy: Among the biologic therapies evaluated for induction therapy, vedolizumab demonstrated the highest efficacy in achieving clinical remission (OR vs daclizumab, 9.09; 95% CI, 1.01-81.61; SUCRA 94.1) and clinical response. Guselkumab showed the lowest risk of recurrence of UC (SUCRA 94.9%), adverse events resulting in treatment discontinuation (SUCRA 94.8%), and serious infections (SUCRA 78.0%). Maintenance Therapy: For maintenance therapy, vedolizumab ranked highest in maintaining clinical remission (OR vs mesalazine 4.36; 95% CI, 1.65-11.49; SUCRA 89.7) and endoscopic improvement (SUCRA 92.6). Infliximab demonstrated the highest efficacy in endoscopic improvement (SUCRA 92.6%). Ustekinumab had the lowest risk of infections (SUCRA 92.9%), serious adverse events (SUCRA 91.3%), and serious infections (SUCRA 67.6%). CONCLUSION: Our network meta-analysis suggests that vedolizumab is the most effective biologic therapy for inducing and maintaining clinical remission in UC patients. Guselkumab shows promise in reducing the risk of recurrence and adverse events during induction therapy. Infliximab is effective in improving endoscopic outcomes during maintenance therapy. Ustekinumab appears to have a favorable safety profile. These findings provide valuable insights for clinicians in selecting the most appropriate biologic therapy for UC patients.

Molecular simulations of sliding on SDS surfactant films.

We use molecular dynamics simulations to study the frictional response of monolayers of the anionic surfactant sodium dodecyl sulfate and hemicylindrical aggregates physisorbed on gold. Our simulations of a sliding spherical asperity reveal the following two friction regimes: at low loads, the films show Amonton's friction with a friction force that rises linearly with normal load, and at high loads, the friction force is independent of the load as long as no direct solid-solid contact occurs. The transition between these two regimes happens when a single molecular layer is confined in the gap between the sliding bodies. The friction force at high loads on a monolayer rises monotonically with film density and drops slightly with the transition to hemicylindrical aggregates. This monotonous increase of friction force is compatible with a traditional plowing model of sliding friction. At low loads, the friction coefficient reaches a minimum at the intermediate surface concentrations. We attribute this behavior to a competition between adhesive forces, repulsion of the compressed film, and the onset of plowing.

Biodegradation of organic compounds in the coal gangue by Bacillus sp. into humic acid.

Coal gangue (CG), one of the world's largest industrial solid wastes produced during coal mining, is extremely difficult to be used owing to its combined contents of clay minerals and organic macromolecules. This study explored a novel process of degrading the harmful organic compounds in the CG into humic acid using a biological method characterized by scanning electron microscope-energy dispersive spectrometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analyzer. The results reveal that adding selected Bacillus sp. to the CG for 40 days can increase the humic acid content by ~ 17 times, reaching 17338.17 mg/kg, which is also the best level for promoting plant growth. FTIR and XPS spectra show that the organic compounds in the CG transforms primarily from C=C to C=O, COOH, and O-H groups, indicating that the organic compounds are gradually oxidized and activated, improving the humic acid concentration of soil. In addition, Bacillus sp. decreases pH and benzo[a]pyrene contents, and increases the content of available nutrients. After microbial degradation, coal gangue can be turned into ecological restoration materials.

Enantioselective Synthesis of N-N Biaryl Atropisomers through Iridium(I)-Catalyzed C-H Alkylation with Acrylates.

Enantioselective synthesis of N-N biaryl atropisomers is an emerging area but remains underexplored. The development of efficient synthesis of N-N biaryl atropisomers is in great demand. Herein, the construction of N-N biaryl atropisomers through iridium-catalyzed asymmetric C-H alkylation is reported for the first time. In the presence of readily available Ir precursor and Xyl-BINAP, a variety of axially chiral molecules based on indole-pyrrole skeleton were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). In addition, N-N bispyrrole atropisomers could also be synthesized in excellent yields and enantioselectivity. This method features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations.

Influential factors and transcriptome analyses of immature diploid embryo anthocyanin accumulation in maize.

BACKGROUND: Anthocyanins are widely applied as a marker for haploid identification after haploid induction in maize. However, the factors affecting anthocyanin biosynthesis in immature embryos and the genes regulating this process remain unclear. RESULTS: In this study, we analyzed the influence of genetic background of the male and female parents, embryo age and light exposure on anthocyanin accumulation in embryos. The results showed that light exposure was the most crucial factor enhancing the pigmentation of immature embryos. The identification accuracy of haploid embryos reached 96.4% after light exposure, but was only 11.0% following dark treatment. The total anthocyanin content was 7-fold higher in immature embryos cultured for 24 h under light conditions compared to embryos cultured in the dark. Transcriptome analysis revealed that the differentially expressed genes between immature embryos cultured for 24 h in dark and light chambers were significantly enriched in the pathways of flavonoid, flavone, flavonol and anthocyanin biosynthesis. Among the genes involved in anthocyanin biosynthesis, five up-regulated genes were identified: F3H, DFR, ANS, F3'H and the MYB transcription factor-encoding gene C1. The expression patterns of 14 selected genes were confirmed using quantitative reverse transcription-polymerase chain reaction. CONCLUSION: Light is the most important factor facilitating anthocyanin accumulation in immature embryos. After 24 h of exposure to light, the expression levels of the structural genes F3H, DFR, ANS, F3'H and transcription factor gene C1 were significantly up-regulated. This study provides new insight into the factors and key genes regulating anthocyanin biosynthesis in immature embryos, and supports improved efficiency of immature haploid embryo selection during doubled haploid breeding of maize.

A single-nucleotide polymorphism in WRKY33 promoter is associated with the cold sensitivity in cultivated tomato.

Natural variations in cis-regulatory regions often affect crop phenotypes by altering gene expression. However, the mechanism of how promoter mutations affect gene expression and crop stress tolerance is still poorly understood. In this study, by analyzing RNA-sequencing (RNA-Seq) data and reverse transcription quantitative real-time PCR validation in the cultivated tomato and its wild relatives, we reveal that the transcripts of WRKY33 are almost unchanged in cold-sensitive cultivated tomato Solanum lycopersicum L. 'Ailsa Craig' but are significantly induced in cold-tolerant wild tomato relatives Solanum habrochaites LA1777 and Solanum pennellii LA0716 under cold stress. Overexpression of SlWRKY33 or ShWRKY33 positively regulates cold tolerance in tomato. Variant of the critical W-box in SlWRKY33 promoter results in the loss of self-transcription function of SlWRKY33 under cold stress. Analysis integrating RNA-Seq and chromatin immunoprecipitation sequencing data reveals that SlWRKY33 directly targets and induces multiple kinases, transcription factors, and molecular chaperone genes, such as CDPK11, MYBS3, and BAG6, thus enhancing cold tolerance. In addition, heat- and Botrytis-induced WRKY33s expression in both wild and cultivated tomatoes are independent of the critical W-box variation. Our findings suggest nucleotide polymorphism in cis-regulatory regions is crucial for different cold sensitivity between cultivated and wild tomato plants.

Nuclear respiratory factor 1 promotes the growth of liver hepatocellular carcinoma cells via E2F1 transcriptional activation.

BACKGROUND: Recent studies have shown that functional mitochondria are essential for cancer cells. Nuclear respiratory factor 1 (NRF1) is a transcription factor that activates mitochondrial biogenesis and the expression of the respiratory chain, but little is known about its role and underlying mechanism in liver hepatocellular carcinoma (LIHC). METHODS: NRF1 expression was analyzed via public databases and 24 paired LIHC samples. Clinical-pathological information and follow-up data were collected from 165 patients with LIHC or online datasets. Furthermore, cellular proliferation and the cell cycle were analyzed by MTT, Clone-forming assay and flow cytometric analyses. NRF1 target genes were analyzed by Chromatin immunoprecipitation sequencing (ChIP-Seq). PCR and WB analysis was performed to detect the expression of related genes. ChIP and luciferase activity assays were used to identify NRF1 binding sites. RESULTS: Our results showed that NRF1 expression was upregulated in LIHC compared to normal tissues. NRF1 expression was associated with tumour size and poor prognosis in patients. Knockdown of NRF1 repressed cell proliferation and overexpression of NRF1 accelerated the G1/S phase transition. Additionally, data from ChIP-seq pointed out that some NRF1 target genes are involved in the cell cycle. Our findings indicated that NRF1 directly binds to the E2F1 promoter as a transcription factor and regulates its gene expression. CONCLUSION: Therefore, this study revealed that NRF1 promotes cancer cell growth via the indirect transcriptional activation of E2F1 and is a potential biomarker in LIHC.

Establishment of a dmp based maternal haploid induction system for polyploid Brassica napus and Nicotiana tabacum.

Doubled haploid (DH) technology is used to obtain homozygous lines in a single generation, a technique that significantly accelerates the crop breeding trajectory. Traditionally, in vitro culture is used to generate DHs, but this technique is limited by species and genotype recalcitrance. In vivo haploid induction (HI) through seed is widely and efficiently used in maize and was recently extended to several other crops. Here we show that in vivo HI can be triggered by mutation of DMP maternal haploid inducer genes in allopolyploid (allotetraploid) Brassica napus and Nicotiana tabacum. We developed a pipeline for selection of DMP orthologs for clustered regularly interspaced palindromic repeats mutagenesis and demonstrated average amphihaploid induction rates of 2.4% and 1.2% in multiple B. napus and N. tabacum genotypes, respectively. These results further confirmed the HI ability of DMP gene in polyploid dicot crops. The DMP-HI system offers a novel DH technology to facilitate breeding in these crops. The success of this approach and the conservation of DMP genes in dicots suggest the broad applicability of this technique in other dicot crops.

Design and performance evaluation of a powered stapler for gastrointestinal anastomosis.

OBJECTIVE: This paper reports the design of a powered stapler for gastrointestinal anastomosis and evaluates its performance. The proposed stapling instrument is intended to simplify and optimize the current procedure of mechanical stapling, while providing controllable operation for the powered stapling procedure, such as conditioning the tissue to the right stage before firing of the stapler. MATERIAL AND METHODS: The feasibility and efficacy of the prototype were assessed by ex vivo experiments with porcine small intestine segments, where the tissue conditioning operation, burst pressure of the stapled intestine samples, and staple malformation rate were examined. RESULTS: The functionality of the developed powered stapler was validated, where the theoretical, numerical, and experimental results agree well with each other. The preliminary results indicated that the proposed tissue conditioning operation could lower the clamping pressure with a maximum level of 1.35 g/mm2. The average burst pressure of the stapled segments (16 samples) is 6.37 kPa, and the maximum malformation rate of the tested groups (five groups, each group with 90 staplers) was 5.56%. CONCLUSION: The developed novel tissue conditioning procedure could reduce the pressure response of the intestine tissue samples. The proposed powered stapler proves effective for performing gastrointestinal anastomosis procedures.

Synthesis of Atropisomers by Transition-Metal-Catalyzed Asymmetric C-H Functionalization Reactions.

Transition-metal-catalyzed enantioselective C-H functionalization has become a powerful strategy for the formation of C-C or C-X bonds, enabling the highly asymmetric synthesis of a wide range of enantioenriched compounds. Atropisomers are widely found in natural products and pharmaceutically relevant molecules, and have also found applications as privileged frameworks for chiral ligands and catalysts. Thus, research into asymmetric routes for the synthesis of atropisomers has garnered great interest in recent years. In this regard, transition-metal-catalyzed enantioselective C-H functionalization has emerged as an atom-economic and efficient strategy toward their synthesis. In this Perspective, the approaches for the synthesis of atropisomers by transition-metal-catalyzed asymmetric C-H functionalization reactions are summarized. The main focus here is on asymmetric catalysis via Pd, Rh, and Ir complexes, which have been the most frequently utilized catalysts among reported enantioselective C-H functionalization reactions. Finally, we discuss limitations on available protocols and give an outlook on possible future avenues of research.