SNRMPACDC: computational model focused on Siamese network and random matrix projection for anticancer synergistic drug combination prediction.

Synergistic drug combinations can improve the therapeutic effect and reduce the drug dosage to avoid toxicity. In previous years, an in vitro approach was utilized to screen synergistic drug combinations. However, the in vitro method is time-consuming and expensive. With the rapid growth of high-throughput data, computational methods are becoming efficient tools to predict potential synergistic drug combinations. Considering the limitations of the previous computational methods, we developed a new model named Siamese Network and Random Matrix Projection for AntiCancer Drug Combination prediction (SNRMPACDC). Firstly, the Siamese convolutional network and random matrix projection were used to process the features of the two drugs into drug combination features. Then, the features of the cancer cell line were processed through the convolutional network. Finally, the processed features were integrated and input into the multi-layer perceptron network to get the predicted score. Compared with the traditional method of splicing drug features into drug combination features, SNRMPACDC improved the interpretability of drug combination features to a certain extent. In addition, the introduction of convolutional networks can better extract the potential information in the features. SNRMPACDC achieved the root mean-squared error of 15.01 and the Pearson correlation coefficient of 0.75 in 5-fold cross-validation of regression prediction for response data. In addition, SNRMPACDC achieved the AUC of 0.91 ± 0.03 and the AUPR of 0.62 ± 0.05 in 5-fold cross-validation of classification prediction of synergistic or not. These results are almost better than all the previous models. SNRMPACDC would be an effective approach to infer potential anticancer synergistic drug combinations.

Assessing parameter efficient methods for pre-trained language model in annotating scRNA-seq data.

Annotating cell types of single-cell RNA sequencing (scRNA-seq) data is crucial for studying cellular heterogeneity in the tumor microenvironment. Recently, large-scale pre-trained language models (PLMs) have achieved significant progress in cell-type annotation of scRNA-seq data. This approach effectively addresses previous methods' shortcomings in performance and generalization. However, fine-tuning PLMs for different downstream tasks demands considerable computational resources, rendering it impractical. Hence, a new research branch introduces parameter-efficient fine-tuning (PEFT). This involves optimizing a few parameters while leaving the majority unchanged, leading to substantial reductions in computational expenses. Here, we utilize scBERT, a large-scale pre-trained model, to explore the capabilities of three PEFT methods in scRNA-seq cell type annotation. Extensive benchmark studies across several datasets demonstrate the superior applicability of PEFT methods. Furthermore, downstream analysis using models obtained through PEFT showcases their utility in novel cell type discovery and model interpretability for potential marker genes. Our findings underscore the considerable potential of PEFT in PLM-based cell type annotation, presenting novel perspectives for the analysis of scRNA-seq data.

Annealing synchronizes the 70S ribosome into a minimum-energy conformation.

Researchers commonly anneal metals, alloys, and semiconductors to repair defects and improve microstructures via recrystallization. Theoretical studies indicate that simulated annealing on biological macromolecules helps predict the final structures with minimum free energy. Experimental validation of this homogenizing effect and further exploration of its applications are fascinating scientific questions that remain elusive. Here, we chose the apo-state 70S ribosome from Escherichia coli as a model, wherein the 30S subunit undergoes a thermally driven intersubunit rotation and exhibits substantial structural flexibility as well as distinct free energy. We experimentally demonstrate that annealing at a fast cooling rate enhances the 70S ribosome homogeneity and improves local resolution on the 30S subunit. After annealing, the 70S ribosome is in a nonrotated state with respect to corresponding intermediate structures in unannealed or heated ribosomes. Manifold-based analysis further indicates that the annealed 70S ribosome takes a narrow conformational distribution and exhibits a minimum-energy state in the free-energy landscape. Our experimental results offer a facile yet robust approach to enhance protein stability, which is ideal for high-resolution cryogenic electron microscopy. Beyond structure determination, annealing shows great potential for synchronizing proteins on a single-molecule level and can be extended to study protein folding and explore conformational and energy landscapes.

Long non-coding RNA CCAT1 acts as an oncogene to promote radiation resistance in lung adenocarcinoma: an epigenomics-based investigation.

Long non-coding RNAs (lncRNAs) appear to be the crucial modulators in various processes and critically influence the oncogenesis. As one of the LncRNAs, LncRNA CCAT1 has been reported to be closely associated with the progression multiple cancers, but its role in modulating the radioresistance of lung adenocarcinoma (LUAD) remains unclear. In our present study, we screened the potential radioresistance related LncRNAs in LUAD based on the data from The Cancer Genome Atlas (TCGA) database. Data suggested that CCAT1 was abundantly expressed in LUAD and CCAT1 was significantly associated with poor prognosis and radioresistance. Moreover, our in vitro experiments showed that radiation treatment could trigger elevated expression of CCAT1 in the human LUAD cell lines. Further loss/gain-of-function investigations indicated that CCAT1 knockdown significantly inhibited cell proliferation, migration and promoted cell apoptosis in NCI-H1299 cells under irradiation, whereas CCAT1 overexpression in A549 cells yield the opposite effects. In summary, we identified the promoting role of CCAT1 in radioresistance of LUAD, which may provide a theoretical basis for radiotherapy sensitization of LUAD.

Prediction of potential miRNA-disease associations based on stacked autoencoder.

In recent years, increasing biological experiments and scientific studies have demonstrated that microRNA (miRNA) plays an important role in the development of human complex diseases. Therefore, discovering miRNA-disease associations can contribute to accurate diagnosis and effective treatment of diseases. Identifying miRNA-disease associations through computational methods based on biological data has been proven to be low-cost and high-efficiency. In this study, we proposed a computational model named Stacked Autoencoder for potential MiRNA-Disease Association prediction (SAEMDA). In SAEMDA, all the miRNA-disease samples were used to pretrain a Stacked Autoencoder (SAE) in an unsupervised manner. Then, the positive samples and the same number of selected negative samples were utilized to fine-tune SAE in a supervised manner after adding an output layer with softmax classifier to the SAE. SAEMDA can make full use of the feature information of all unlabeled miRNA-disease pairs. Therefore, SAEMDA is suitable for our dataset containing small labeled samples and large unlabeled samples. As a result, SAEMDA achieved AUCs of 0.9210 and 0.8343 in global and local leave-one-out cross validation. Besides, SAEMDA obtained an average AUC and standard deviation of 0.9102 ± /-0.0029 in 100 times of 5-fold cross validation. These results were better than those of previous models. Moreover, we carried out three case studies to further demonstrate the predictive accuracy of SAEMDA. As a result, 82% (breast neoplasms), 100% (lung neoplasms) and 90% (esophageal neoplasms) of the top 50 predicted miRNAs were verified by databases. Thus, SAEMDA could be a useful and reliable model to predict potential miRNA-disease associations.

The lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branch number by affecting brassinosteroid biosynthesis.

Branch number is one of the most important agronomic traits of fruit trees such as peach. Little is known about how LncRNA and/or miRNA modules regulate branching through transcription factors. Here, we used molecular and genetic tools to clarify the molecular mechanisms underlying brassinosteroid (BR) altering plant branching. We found that the number of sylleptic branch and BR content in pillar peach ('Zhaoshouhong') was lower than those of standard type ('Okubo'), and exogenous BR application could significantly promote branching. PpTCP4 expressed great differentially comparing 'Zhaoshouhong' with 'Okubo'. PpTCP4 could directly bind to DWARF2 (PpD2) and inhibited its expression. PpD2 was the only one differentially expressed key gene in the path of BR biosynthesis. At the same time, PpTCP4 was identified as a target of miR6288b-3p. LncRNA1 could act as the endogenous target mimic of miR6288b-3p and repress expression of miR6288b-3p. Three deletions and five SNP sites of lncRNA1 promoter were found in 'Zhaoshouhong', which was an important cause of different mRNA level of PpTCP4 and BR content. Moreover, overexpressed PpTCP4 significantly inhibited branching. A novel mechanism in which the lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branching number was proposed.

Competition between Self-Assembly and Phase Separation Governs High-Temperature Condensation of a DNA Liquid.

In many biopolymer solutions, attractive interactions that stabilize finite-sized clusters at low concentrations also promote phase separation at high concentrations. Here we study a model biopolymer system that exhibits the opposite behavior, whereby self-assembly of DNA oligonucleotides into finite-sized, stoichiometric clusters tends to inhibit phase separation. We first use microfluidics-based experiments to map a novel phase transition in which the oligonucleotides condense as the temperature increases at high concentrations of divalent cations. We then show that a theoretical model of competition between self-assembly and phase separation quantitatively predicts changes in experimental phase diagrams arising from DNA sequence perturbations. Our results point to a general mechanism by which self-assembly shapes phase boundaries in complex biopolymer solutions.

Promoting Catalytic Performance Involving Hydrogen Spillover by Ion Exchange of Pt@A Catalysts to Regulate Reactant Adsorption.

Zeolite-encapsulated metal nanoparticle systems have exhibited interesting catalytic performances via the hydrogen spillover process, yet how to further utilize the function of zeolite supports to promote catalytic properties in such a process is still challenging and has rarely been investigated. Herein, to address this issue, the strategy to strengthen the adsorption energy of reactant onto the zeolite surface via a simple ion exchange method has been implemented. Ion-exchanged linde type A (LTA) zeolite-encapsulated platinum nanoclusters (Pt@NaA, Pt@HA, Pt@KA, and Pt@CaA) were prepared to study the influence of ion exchange on the catalytic performance in the model reaction of hydrogenation of acetophenone to 1-phenylethanol. The reaction results showed that the Pt@CaA catalyst exhibited the best catalytic activity in the series of encapsulated catalysts, and the selectivity of 1-phenylethanol approached 100%. As revealed by density functional theory (DFT) calculations and acetophenone temperature-programmed desorption (acetophenone-TPD) experiments, in comparison with introduced cations of Na+, H+, and K+, ion-exchanged Ca2+ on the zeolite maximumly enhanced the adsorption of carbonyl groups in acetophenone, playing a critical role in achieving the highest activity and excellent catalytic selectivity among the Pt@A catalysts.

Electrochromic Smart Window Based on Transition-Metal Phthalocyanine Derivatives.

Phthalocyanines have been widely investigated as electrochromic materials because of their large conjugated structure. However, they have shown limited applicability due to their complex electrochromism mechanism and low solubility in common organic solvents. Replacement of central metal ions in phthalocyanines affects their stability and is responsible for various electrochromic phenomena, such as color change. Herein, the relationship between the electron d-orbital arrangement in the outermost layer of transition metals and the electrochromic stability of phthalocyanine derivatives has been investigated. An enhanced solubility of phthalocyanines in organic solvents was obtained through the introduction of quaternary tert-butyl substitution. Electrochromic devices fabricated with transition-metal phthalocyanine derivatives showed high response speeds and good stability. The fast color-switching feature between blue/green and blue/purple makes it a promising candidate for smart windows and adaptive camouflage applications.

Facial adult female acne in China: An analysis based on artificial intelligence over one million.

BACKGROUND: To further clarify the acne profile of Chinese adult women, we included 1,156,703 adult women. An artificial intelligence algorithm was used to analyze images taken by high-resolution mobile phones to further explore acne levels in Chinese adult women. METHOD: In this study, we assessed the severity of acne by evaluating patients' selfies through a smartphone application. Furthermore, we gathered basic user information through a questionnaire, including details such as age, gender, skin sensitivity, and dietary habits. RESULTS: This study showed a gradual decrease in acne severity from the age of 25 years. A trough was reached between the ages of 40 and 44, followed by a gradual increase in acne severity. In terms of skin problems and acne severity, we have found that oily skin, hypersensitive skin, frequent makeup application and unhealthy dietary habits can affect the severity of acne. For environment and acne severity, we observed that developed city levels, cold seasons and high altitude and strong radiation affect acne severity in adult women. For the results of the AI analyses, the severity of blackheads, pores, dark circles and skin roughness were positively associated with acne severity in adult women. CONCLUSIONS: AI analysis of high-res phone images in Chinese adult women reveals acne severity trends. Severity decreases after 25, hits a low at 40-44, then gradually rises. Skin type, sensitivity, makeup, diet, urbanization, seasons, altitude, and radiation impact acne. Blackheads, pores, dark circles, and skin roughness are linked to acne severity. These findings inform personalized skincare and public health strategies for adult women.

Global and Latest Hotspots of Female Genital Plastic Surgery in the Past 20 Years: A Bibliometric and Visualized Review.

BACKGROUND: An increasing number of surgical and nonsurgical interventions are available in the field of female genital plastic surgery. The rate of female genital plastic surgery has increased by nearly 220 percent over the past 5 years. Despite several studies on the topic, no relevant bibliometric analysis has been conducted. METHODS: We searched the Web of Science Core Collection for articles related to female genital plastic surgery. CiteSpace 6.1.R2 (Drexel University, USA) and VOSviewer 1.6.10.0 (Leiden University, the Netherlands) were used, and national distribution, institutions, journals, authors, and key words were analyzed and calculated. RESULTS: From 2003 to 2022, 1299 papers in the field of female genital plastic surgery were retrieved. There were more articles produced in the United States, and there were also two institutions in the Netherlands that were highly productive. A wide and close relationship has been established between researchers and institutions conducting female genital plastic surgery. Professor Bouman MB published the most articles on female genital plastic surgery in the Journal of Sexual Medicine. Female genital plastic surgery dominated the top 10 references with the highest local citation score. There were four clusters of key words with the most citations, and the most recently trending key words were "vaginal agenesis," "transgender," and "congenital adrenal hyperplasia." CONCLUSIONS: The purpose of this article is to provide a summary of the current research status focusing on female genital plastic surgery. It is hoped that more efforts will be made to promote the development of female genital plastic surgery in the future.

Application of Chlorophyll Fluorescence Analysis Technique in Studying the Response of Lettuce (Lactuca sativa L.) to Cadmium Stress.

To reveal the impact of cadmium stress on the physiological mechanism of lettuce, simultaneous determination and correlation analyses of chlorophyll content and photosynthetic function were conducted using lettuce seedlings as the research subject. The changes in relative chlorophyll content, rapid chlorophyll fluorescence induction kinetics curve, and related chlorophyll fluorescence parameters of lettuce seedling leaves under cadmium stress were detected and analyzed. Furthermore, a model for estimating relative chlorophyll content was established. The results showed that cadmium stress at 1 mg/kg and 5 mg/kg had a promoting effect on the relative chlorophyll content, while cadmium stress at 10 mg/kg and 20 mg/kg had an inhibitory effect on the relative chlorophyll content. Moreover, with the extension of time, the inhibitory effect became more pronounced. Cadmium stress affects both the donor and acceptor sides of photosystem II in lettuce seedling leaves, damaging the electron transfer chain and reducing energy transfer in the photosynthetic system. It also inhibits water photolysis and decreases electron transfer efficiency, leading to a decline in photosynthesis. However, lettuce seedling leaves can mitigate photosystem II damage caused by cadmium stress through increased thermal dissipation. The model established based on the energy captured by a reaction center for electron transfer can effectively estimate the relative chlorophyll content of leaves. This study demonstrates that chlorophyll fluorescence techniques have great potential in elucidating the physiological mechanism of cadmium stress in lettuce, as well as in achieving synchronized determination and correlation analyses of chlorophyll content and photosynthetic function.

Nerve Distribution Method is Superior to the Conventional Method in BoNT-A Treatment of Trapezius Hypertrophy: A Randomized Controlled Trial.

The contour of the neck and shoulder is defined by the trapezius muscle (TM). Beyond facial procedures, botulinum toxin A (BoNT-A) injections has been increasingly adopted to create a smooth shoulder line. Several studies described the intramuscular nerve branching and the pattern of perforating branch of the accessory nerve in the trapezius muscle, providing essential information for botulinum neurotoxin injection. To this date, research groups seldom perform clinical investigations, especially randomized controlled trials, that demonstrates whether BoNT-A injections using the nerve distribution method for aesthetic purposes is more effective. Patients met the criteria for inclusion were randomized to either the Nerve Distribution group (ND group) or control group. Control group patients received injection using the conventional method while ND group patients received the nerve distribution method. Photographic and ultrasonographic evaluations were carried out at baseline, one month, three months, and six months after the procedure. Patients were also required to complete a questionnaire to evaluate their feedbacks to the injection. After screening, 30 healthy young Chinese women were included. At one-month follow-up, no statistically significant difference was observed between the two methods. At the three-month follow-up, the reduction of the TM thickness for the ND group (0.21 ± 0.09 cm) was more than that for the control group (0.27 ± 0.08 cm), with p = 0.047*. Similar differences were observed for the reduction of the shoulder area proportion (p = 0.031*) and the shoulder angle (p = 0.035*). At the six-month follow-up, the reduction in TM thickness in the ND group (0.2 ± 0.09 cm) was more than that of the control group (0.28 ± 0.06 cm), with p = 0.041*. The global aesthetic improvement scale feedbacks of the two methods showed no significant difference (3.4 ± 0.71 vs 3.8 ± 0.91, p = 0.207). The patients did not experience severe side effects. Compared to the conventional injection method, the nerve distribution method is more effective in reducing the trapezius muscle thickness, shoulder area proportion, and shoulder angle at three months, and shows longer lasting effects. The results of this study introduce unique insights into the design and tailoring of treatment protocols for shoulder-line contouring using BoNT-A.Level of Evidence I This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Gender- and Age-Related Characterization of Lower Eyelid Morphology: Three-Dimensional Analysis in a Chinese Population.

BACKGROUND: The lower eyelid region is a critical component of the face. It is essential to establish anthropometric reference values for the evaluation of aging, surgical planning and assessment of outcomes in periocular esthetic and rejuvenation procedures. This study aims to provide comprehensive anthropometric data on the Chinese lower eyelid region, into account factors such as sex and age, through three-dimensional imaging analysis. METHOD: Three-dimensional facial images were obtained from 84 healthy Chinese individuals aged between 20-35 and 50-65 years, as well as eight patients aged between 20 and 35 who presented with eyelid bags. A total of 27 landmarks were identified, leading to the generation of corresponding 21 lines, 5 curves, 4 angles, 2 areas and 5 ratios. The measurements were compared among different age groups, genders and young patients with or without eyelid bags. RESULTS: Compared to females, males exhibited a more elongated palpebral fissure, lower tear trough and lid-cheek junction, smaller inner and outer canthus angles, as well as a larger area and proportion of the lower palpebral region. As age progressed, the height and width of the palpebral fissure and inner canthus angle decreased gradually, which was accompanied by sagging of the tear trough and lid-cheek junction, an increase in lower eyelid area and swelling of the lower eyelid. Young patients undergoing eyelid bags demonstrated larger and more swelling lower eyelid which held clinical significance for rejuvenation surgery. CONCLUSION: Males exhibited a higher proportion of the brow-eye unit occupied by the lower eyelid region compared to females. Elderly individuals displayed noticeable drooping of the tear trough and lid-cheek junction, accompanied by swelling in the lower palpebral region. These findings can serve as standard references for esthetic procedures and reconstructive periocular operations. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to Table of Contents or online Instructions to Authors www.springer.com/00266.

Global research status of localised scleroderma reported over the period 1993-2022: A 30-year bibliometric analysis.

Localised scleroderma predominantly affects the skin with an unknown aetiology. Despite its clinical importance, no comprehensive bibliometric analysis has been conducted to assess the existing research landscape and future prospects for localised scleroderma. The articles related to localised scleroderma were retrieved from the WoSCC database and analysed by VOSviewer 1.6.10.0 (Leiden University, Netherlands), CiteSpace 6.1.R1 (Dreiser University, USA), and HistCite 2.1 (New York, United States). 2049 research papers pertaining to localised scleroderma spanning the years from 1993 to 2022 were extracted from the WoSCC database. The United States exhibited the highest productivity with 644 papers, accounting for 31.43% of the total output, followed by Germany with 206 papers (10.05%) and Italy with 200 papers (9.76%). Regarding academic institutions and journals, the University of Texas System and Dermatology published the most significant number of papers, and Professor Ihn, H emerged as the most prolific contributor among scholars. The top 10 cited references primarily concentrated on the diagnosis and treatment of localised scleroderma. "Phototherapy" and "methotrexate (MTX)" surfaced as the most recent and noteworthy keywords, representing the research hotspots in the domain of localised scleroderma. This bibliometric analysis furnishes valuable insights into the contemporary research landscape of localised scleroderma.

A Unique Etching-Doping Route to Fe/Mo Co-Doped Ni Oxyhydroxide Catalyst for Enhanced Oxygen Evolution Reaction.

Fe-doped Ni (oxy)hydroxide shows intriguing activity toward oxygen evolution reaction (OER) in alkaline solution, yet it remains challenging to further boost its performance. In this work, a ferric/molybdate (Fe3+ /MoO4 2- ) co-doping strategy is reported to promote the OER activity of Ni oxyhydroxide. The reinforced Fe/Mo-doped Ni oxyhydroxide catalyst supported by nickel foam (p-NiFeMo/NF) is synthesized via a unique oxygen plasma etching-electrochemical doping route, in which precursor Ni(OH)2 nanosheets are first etched by oxygen plasma to form defect-rich amorphous nanosheets, followed by electrochemical cycling to trigger simultaneously Fe3+ /MoO4 2- co-doping and phase transition. This p-NiFeMo/NF catalyst requires an overpotential of only 274 mV to reach 100 mA cm-2 in alkaline media, exhibiting significantly enhanced OER activity compared to NiFe layered double hydroxide (LDH) catalyst and other analogs. Its activity does not fade even after 72 h uninterrupted operation. In situ Raman analysis reveals that the intercalation of MoO4 2- is able to prevent the over-oxidation of NiOOH matrix from ß to γ phase, thus keeping the Fe-doped NiOOH at the most active state.

Deep-belief network for predicting potential miRNA-disease associations.

MicroRNA (miRNA) plays an important role in the occurrence, development, diagnosis and treatment of diseases. More and more researchers begin to pay attention to the relationship between miRNA and disease. Compared with traditional biological experiments, computational method of integrating heterogeneous biological data to predict potential associations can effectively save time and cost. Considering the limitations of the previous computational models, we developed the model of deep-belief network for miRNA-disease association prediction (DBNMDA). We constructed feature vectors to pre-train restricted Boltzmann machines for all miRNA-disease pairs and applied positive samples and the same number of selected negative samples to fine-tune DBN to obtain the final predicted scores. Compared with the previous supervised models that only use pairs with known label for training, DBNMDA innovatively utilizes the information of all miRNA-disease pairs during the pre-training process. This step could reduce the impact of too few known associations on prediction accuracy to some extent. DBNMDA achieves the AUC of 0.9104 based on global leave-one-out cross validation (LOOCV), the AUC of 0.8232 based on local LOOCV and the average AUC of 0.9048 ± 0.0026 based on 5-fold cross validation. These AUCs are better than other previous models. In addition, three different types of case studies for three diseases were implemented to demonstrate the accuracy of DBNMDA. As a result, 84% (breast neoplasms), 100% (lung neoplasms) and 88% (esophageal neoplasms) of the top 50 predicted miRNAs were verified by recent literature. Therefore, we could conclude that DBNMDA is an effective method to predict potential miRNA-disease associations.

Construction of [NbO]6-x -xS Structure to Change Charge Density and Regulate Spontaneous Polarization to Achieve Efficient Pyro-Photo-Electric Water Splitting System of NaNbO3.

Pyroelectric materials in the field of photoelectrochemical (PEC) water splitting still face the problems of difficult low spontaneous polarization intensity and excessive carrier recombination. Based on the above problems, we altered the interaction between S-Nb-S in the [NbO]6-x -xS structure, and the constructed [NbO]6-x -xS structure achieved the regulation of charge density change and spontaneous polarization. The results show that under the stimulation of light and temperature fluctuations, the current density of the NS-4 photoanode is as high as 0.574 mA/cm2 at 1.23 VRHE , which is about 1.59 times higher than the pure NaNbO3 current density value, and the NS -4 photoanode achieves IPCE value of 16.08 %. The first-principles density-functional theory calculations (DFT) reveal the principle of the [NbO]6-x -xS structure for the suppression function of the carrier recombination and the improvement function of the pyroelectric effect. The analysis shows that the S-doping leads to the weakening of S-Nb-S interactions in the [NbO]6-x -xS structure, which improves the pyroelectric effect and suppresses the photo/pyro-generated carrier recombination, and effectively enhances the performance of the pyro-photo-electric synergistic water splitting system. This work promotes the development of pyroelectric materials in the field of photoelectrochemical water splitting.

Polyborosilazane with Broadly Tunable Boron Content for SiBCN Ceramics.

The high-temperature durability of SiBCN ceramics is significantly influenced by the boron concentration and synthesis methods. Although single-source synthetic routes allow one to obtain homogeneous ceramics at the atomic level, the content of the boron element therein is limited by borane (BH3). In this study, the synthesis of carborane-substituted polyborosilazanes was performed via a simple one-pot reaction of polysilazanes with alkyne bonds on the main chain and decaborododecahydrodiacetonitrile complexes with different molar ratios. This enabled one to vary the boron content from ∼0 to 40.00 wt %. The ceramic yields were in the range of 50.92-90.81 wt %. Independently of the borane concentration, SiBCN ceramics started to crystallize at 1200 °C, and B4C appeared as a new crystalline phase with increasing boron content. The introduction of boron inhibited the crystallization of Si3N4 and increased the crystallization temperature of SiC. The presence of the B4C phase improved both thermal stability and functional properties such as neutron-shielding characteristics of the ceramics. Therefore, this research opens up new prospects for the design of novel polyborosilanzes with great application potential.

Synthesis of the ABC ring system of kadlongilactones.

A racemic approach towards the synthesis of the ABC (7/7/5) ring system of Schisandra triterpenoid kadlongilactones is described. The synthesis features two key transformations: (1) conjugate addition followed by iodolactonization to build the cis-fused 7/7 ring; and (2) conjugate addition-Rubottom oxidation cascade followed by ring-closing metathesis to construct the 7/7/5 tricyclic ring.