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Genome assembly remains to be a major task in genomic research. Despite the development over the past decades of different assembly software programs and algorithms, it is still a great challenge to assemble a complete genome without any gaps. With the latest DNA circular consensus sequencing (CCS) technology, several assembly programs can now build a genome from raw sequencing data to contigs; however, some complex sequence regions remain as unresolved gaps. Here, we present a novel gap-filling software, DEGAP (Dynamic Elongation of a Genome Assembly Path), that resolves gap regions by utilizing the dual advantages of accuracy and length of high-fidelity (HiFi) reads. DEGAP identifies differences between reads and provides 'GapFiller' or 'CtgLinker' modes to eliminate or shorten gaps in genomes. DEGAP adopts an iterative elongation strategy that automatically and dynamically adjusts parameters according to three complexity factors affecting the genome to determine the optimal extension path. DEGAP has already been successfully applied to decipher complex genomic regions in several projects and may be widely employed to generate more gap-free genomes.
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Algoritmos , Software , Genômica/métodos , Análise de Sequência de DNA/métodos , Genoma , Sequenciamento de Nucleotídeos em Larga Escala/métodosRESUMO
MOTIVATION: Protein sequence database search and multiple sequence alignment generation is a fundamental task in many bioinformatics analyses. As the data volume of sequences continues to grow rapidly, there is an increasing need for efficient and scalable multiple sequence query algorithms for super-large databases without expensive time and computational costs. RESULTS: We introduce Chorus, a novel protein sequence query system that leverages parallel model and heterogeneous computation architecture to enable users to query thousands of protein sequences concurrently against large protein databases on a desktop workstation. Chorus achieves over 100× speedup over BLASTP without sacrificing sensitivity. We demonstrate the utility of Chorus through a case study of analyzing a â¼1.5-TB large-scale metagenomic datasets for novel CRISPR-Cas protein discovery within 30 min. AVAILABILITY AND IMPLEMENTATION: Chorus is open-source and its code repository is available at https://github.com/Bio-Acc/Chorus.
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Algoritmos , Software , Sequência de Aminoácidos , Proteínas , Bases de Dados de ProteínasRESUMO
The practical application of thermoelectric devices requires both high-performance n-type and p-type materials of the same system to avoid possible mismatches and improve device reliability. Currently, environmentally friendly SnTe thermoelectrics have witnessed extensive efforts to develop promising p-type transport, making it rather urgent to investigate the n-type counterparts with comparable performance. Herein, we develop a stepwise optimization strategy for improving the transport properties of n-type SnTe. First, we improve the n-type dopability of SnTe by PbSe alloying to narrow the band gap and obtain n-type transport in SnTe with halogen doping over the whole temperature range. Then, we introduce additional Pb atoms to compensate for the cationic vacancies in the SnTe-PbSe matrix, further enhancing the electron carrier concentration and electrical performance. Resultantly, the high-ranged thermoelectric performance of n-type SnTe is substantially optimized, achieving a peak ZT of â¼0.75 at 573 K with a high average ZT (ZTave) exceeding 0.5 from 300 to 823 K in the (SnTe0.98I0.02)0.6(Pb1.06Se)0.4 sample. Moreover, based on the performance optimization on n-type SnTe, for the first time, we fabricate an all-SnTe-based seven-pair thermoelectric device. This device can produce a maximum output power of â¼0.2 W and a conversion efficiency of â¼2.7% under a temperature difference of 350 K, demonstrating an important breakthrough for all-SnTe-based thermoelectric devices. Our research further illustrates the effectiveness and application potential of the environmentally friendly SnTe thermoelectrics for mid-temperature power generation.
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Gastrointestinal cancer (GIC) is the most prevalent and highly metastatic malignant tumor and has a significant impact on mortality rates. Nevertheless, the swift advancement of contemporary technology has not seamlessly aligned with the evolution of detection methodologies, resulting in a deficit of innovative and efficient clinical assays for GIC. Given that exosomes are preferentially released by a myriad of cellular entities, predominantly originating from neoplastic cells, this confers exosomes with a composition enriched in cancer-specific constituents. Furthermore, exosomes exhibit ubiquitous presence across diverse biological fluids, endowing them with the inherent advantages of non-invasiveness, real-time monitoring, and tumor specificity. The unparalleled advantages inherent in exosomes render them as an ideal liquid biopsy biomarker for early diagnosis, prognosticating the potential development of GIC metastasis.In this review, we summarized the latest research progress and possible potential targets on cancer-derived exosomes (CDEs) in GIC with an emphasis on the mechanisms of exosome promoting cancer metastasis, highlighting the potential roles of CDEs as the biomarker and treatment in metastatic GIC.
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Exossomos , Neoplasias Gastrointestinais , Humanos , Exossomos/patologia , Biomarcadores Tumorais , Biomarcadores , Neoplasias Gastrointestinais/diagnóstico , Neoplasias Gastrointestinais/patologia , Biópsia Líquida/métodosRESUMO
BACKGROUND: Information transmission between primary tumor cells and immunocytes or stromal cells in distal organs is a critical factor in the formation of pre-metastatic niche (PMN). Understanding this mechanism is essential for developing effective therapeutic strategy against tumor metastasis. Our study aims to prove the hypothesis that circ-0034880-enriched tumor-derived extracellular vesicles (TEVs) mediate the formation of PMN and colorectal cancer liver metastasis (CRLM), and targeting circ-0034880-enriched TEVs might be an effective therapeutic strategy against PMN formation and CRLM. METHODS: We utilized qPCR and FISH to measure circRNAs expression levels in human CRC plasma, primary CRC tissues, and liver metastatic tissues. Additionally, we employed immunofluorescence, RNA sequencing, and in vivo experiments to assess the effect mechanism of circ-0034880-enriched TEVs on PMN formation and CRC metastasis. DARTS, CETSA and computational docking modeling were applied to explore the pharmacological effects of Ginsenoside Rb1 in impeding PMN formation. RESULTS: We found that circ-0034880 was highly enriched in plasma extracellular vesicles (EVs) derived from CRC patients and closely associated with CRLM. Functionally, circ-0034880-enriched TEVs entered the liver tissues and were absorbed by macrophages in the liver through bloodstream. Mechanically, TEVs-released circ-0034880 enhanced the activation of SPP1highCD206+ pro-tumor macrophages, reshaping the metastasis-supportive host stromal microenvironment and promoting overt metastasis. Importantly, our mechanistic findings led us to discover that the natural product Ginsenoside Rb1 impeded the activation of SPP1highCD206+ pro-tumor macrophages by reducing circ-0034880 biogenesis, thereby suppressing PMN formation and inhibiting CRLM. CONCLUSIONS: Circ-0034880-enriched TEVs facilitate strong interaction between primary tumor cells and SPP1highCD206+ pro-tumor macrophages, promoting PMN formation and CRLM. These findings suggest the potential of using Ginsenoside Rb1 as an alternative therapeutic agent to reshape PMN formation and prevent CRLM.
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Neoplasias Colorretais , Vesículas Extracelulares , Neoplasias Hepáticas , Osteopontina , RNA Circular , Humanos , Neoplasias Colorretais/patologia , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Vesículas Extracelulares/metabolismo , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/patologia , Camundongos , Animais , RNA Circular/genética , Osteopontina/metabolismo , Osteopontina/genética , Linhagem Celular Tumoral , Microambiente Tumoral , Masculino , Feminino , Macrófagos Associados a Tumor/metabolismo , Macrófagos Associados a Tumor/efeitos dos fármacos , Macrófagos Associados a Tumor/imunologia , Macrófagos/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Ensaios Antitumorais Modelo de Xenoenxerto , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacosRESUMO
Bismuth sulfide is a promising thermoelectric material because of its low cost and toxicity; however, its low electrical conductivity limits its thermoelectric properties. In this study, Bi2S3+x wt% HfCl4 (x = 0, 0.25, 0.5, 0.75, and 1.0) bulk samples are fabricated using a combination of melting and spark plasma sintering. The microstructures, electronic structures, and thermoelectric properties of the composites are characterized. The results of electronic structure calculations show that doping with HfCl4 produces an impurity energy level that narrows the bandgap and allows the Fermi energy level to enter the conduction band, leading to a favorable increase in carrier concentration. By regulating the HfCl4 doping concentration, the electrical conductivity of the 0.75 wt% doped sample reaches 253 Scm-1 at 423 K and its maximum ZT value is 0.47 at 673 K. Moreover, the sample is compounded with Bi2S3 nanorods prepared by the hydrothermal method, reducing thermal conductivity by 30% due to the introduction of additional interfaces and pores. This resulted in a final ZT value of 0.61 at 673 K, which is approximately eight times higher than that of pure Bi2S3. This step-by-step optimization approach provides a valuable methodology for enhancing the performance of other thermoelectric material systems.
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Soft robots based on flexible materials have attracted the attention due to high flexibility and great environmental adaptability. Among the common driving modes, electricity, light, and magnetism have the limitations of wiring, poor penetration capability, and sophisticated equipment, respectively. Here, an emerging wireless driving mode is proposed for the soft crawling robot based on wireless power transfer (WPT) technology. The receiving coil at the robot's tail, as an energy transfer station, receives energy from the transmitting coil and supplies the electrothermal responsiveness to drive the robot's crawling. By regulating the WPT's duration to control the friction between the robot and the ground, bidirectional crawling is realized. Furthermore, the receiving coil is also employed as a sensory organ to equip the robot with localization, ID recognition, and sensing capabilities based on electromagnetic coupling. This work provides an innovative and promising strategy for the design and integration of soft crawling robots, exhibiting great potential in the field of intelligent robots.
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The scarcity of Te hampers the widespread use of Bi2Te3-based thermoelectric modules. Here, the thermoelectric module potential of PbSe is investigated by improving its carrier mobility. Initially, large PbSe crystals are grown with the temperature gradient method to mitigate grain boundary effects on carrier transport. Subsequently, light doping with <1mole halogens (Cl/Br/I) increases room-temperature carrier mobility to ~1600 cm2 V-1 s-1, achieved by reducing carrier concentration compared to traditional heavy doping. Crystal growth design and light doping enhance carrier mobility without affecting effective mass, resulting in a high power factor ~40 µW cm-1 K-2 in PbSe-Cl/Br/I crystals at 300 K. Additionally, Cl/Br/I doping reduces thermal conductivity and bipolar diffusion, leading to significantly lower thermal conductivity at high temperature. Enhanced carrier mobility and suppressed bipolar effect boost ZT values across the entire temperature range in n-type PbSe-Cl/Br/I crystals. Specifically, ZT values of PbSe-Br crystal reach ~0.6 at 300 K, ~1.2 at 773 K, and the average ZT (ZTave) reaches ~1.0 at 300-773 K. Ultimately, ~5.8% power generation efficiency in a PbSe single leg with a maximum temperature cooling difference of 40 K with 7-pair modules is achieved. These results indicate the potential for cost-effective and high-performance thermoelectric cooling modules based on PbSe.
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ω-Transaminases (ω-TAs) are attractive biocatalysts asymmetrically catalyzing ketones to chiral amines. However, poor non-native catalytic activity and substrate promiscuity severely hamper its wide application in industrial production. Protein engineering efforts have generally focused on reshaping the substrate-binding pockets of ω-TAs. However, hotspots around the substrate tunnel as well as distant sites outside the pockets may also affect its activity. In this study, the ω-TA from Bacillus megaterium (BmeTA) was selected for engineering. The tunnel mutation Y164F synergy with distant mutation A245T which was acquired through a multiple sequence alignment showed improved soluble expression, a 3.7-fold higher specific activity and a 19.9-fold longer half-life at 45 °C. Molecule Dynamics simulation explains the mechanism of improved catalytic activity, enhanced thermostability and improved soluble expression of BmeTAY164F/A245T(2â M). Finally, the resting cells of 2â M were used for biocatalytic processes. 450â mM of S-methoxyisopropylamine (S-MOIPA) was obtained with an ee value of 97.3 % and a conversion rate of 90 %, laying the foundation for its industrial production. Mutant 2â M was also found to be more advantageous in catalyzing the transamination of various ketones. These results demonstrated that sites that are far away from the active center also play an important role in the redesign of ω-TAs.
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Aminas , Bacillus megaterium , Transaminases , Bacillus megaterium/enzimologia , Transaminases/metabolismo , Transaminases/genética , Transaminases/química , Aminas/química , Aminas/metabolismo , Engenharia de Proteínas , Biocatálise , Estereoisomerismo , Simulação de Dinâmica Molecular , Especificidade por Substrato , Sequência de AminoácidosRESUMO
Osteoporosis-pseudoglioma syndrome (OPPG) and LRP5 high bone mass (LRP5-HBM) are two rare bone diseases with opposite clinical symptoms caused by loss-of-function and gain-of-function mutations in LRP5. Bisphosphonates are an effective treatment for OPPG patients. LRP5-HBM has a benign course, and age-related bone loss is found in one LRP5-HBM patient. PURPOSE: Low-density lipoprotein receptor-related protein 5 (LRP5) is involved in the canonical Wnt signaling pathway. The gain-of-function mutation leads to high bone mass (LRP5-HBM), while the loss-of-function mutation leads to osteoporosis-pseudoglioma syndrome (OPPG). In this study, the clinical manifestations, disease-causing mutations, treatment, and follow-up were summarized to improve the understanding of these two diseases. METHODS: Two OPPG patients and four LRP5-HBM patients were included in this study. The clinical characteristics, biochemical and radiological examinations, pathogenic mutations, and structural analysis were summarized. Furthermore, several patients were followed up to observe the treatment effect and disease progress. RESULTS: Congenital blindness, persistent bone pain, low bone mineral density (BMD), and multiple brittle fractures were the main clinical manifestations of OPPG. Complex heterozygous mutations were detected in two OPPG patients. The c.1455G > T mutation in exon 7 was first reported. During the follow-up, BMD of two patients was significantly improved after bisphosphonate treatment. On the contrary, typical clinical features of LRP5-HBM included extremely high BMD without fractures, torus palatinus and normal vision. X-ray showed diffuse osteosclerosis. Two heterozygous missense mutations were detected in four patients. In addition, age-related bone loss was found in one LRP5-HBM patient after 12-year of follow-up. CONCLUSION: This study deepened the understanding of the clinical characteristics, treatment, and follow-up of OPPG and LRP5-HBM; expanded the pathogenic gene spectrum of OPPG; and confirmed that bisphosphonates were effective for OPPG. Additionally, it was found that Ala242Thr mutation could not protect LRP5-HBM patients from age-related bone loss. This phenomenon deserves further study.
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Conservadores da Densidade Óssea , Densidade Óssea , Difosfonatos , Proteína-5 Relacionada a Receptor de Lipoproteína de Baixa Densidade , Mutação , Humanos , Proteína-5 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Densidade Óssea/fisiologia , Densidade Óssea/genética , Feminino , Conservadores da Densidade Óssea/uso terapêutico , Conservadores da Densidade Óssea/farmacologia , Masculino , Difosfonatos/uso terapêutico , Difosfonatos/farmacologia , Adulto , Seguimentos , Osteogênese Imperfeita/genética , Osteogênese Imperfeita/fisiopatologia , Osteogênese Imperfeita/tratamento farmacológico , Osteogênese Imperfeita/complicações , Adolescente , Adulto Jovem , Pessoa de Meia-Idade , CriançaRESUMO
INTRODUCTION: Atopic dermatitis (AD) is a prevalent and chronic inflammatory skin disease characterized by Th2 cell-mediated type 2 inflammation. Emerging evidence indicated that AD patients exhibit an increased incidence of oral disorders. In the present study, we sought mechanistic insights into how AD affects periodontitis. METHODS: Onset of AD was induced by 2,4-dinitrochlorobenzene (DNCB). Furthermore, we induced periodontitis (P) in AD mice. The effect of AD in promoting inflammation and bone resorption in gingiva was evaluated. Hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, immunofluorescence assay, and flow cytometry were used to investigate histomorphology and cytology analysis, respectively. RNA sequencing of oral mucosa is used tissues to further understand the dynamic transcriptome changes. 16S rRNA microbial analysis is used to profile oral microbial composition. RESULTS: Compared to control group, mice in AD group showed inflammatory signatures and infiltration of a proallergic Th2 (Th2A)-like subset in oral mucosa but not periodontitis, as identified by not substantial changes in mucosa swelling, alveolar bone loss, and TRAP+ osteoclasts infiltration. Similarly, more Th2A-like cell infiltration and interleukin-4 levels were significantly elevated in the oral mucosa of DNCB-P mice compared to P mice. More importantly, AD exacerbates periodontitis when periodontitis has occurred and the severity of periodontitis increased with aggravation of dermatitis. Transcriptional analysis revealed that aggravated periodontitis was positively correlated with more macrophage infiltration and abundant CCL3 secreted. AD also altered oral microbiota, indicating the re-organization of extracellular matrix. CONCLUSIONS: These data provide solid evidence about exacerbation of periodontitis caused by type 2 dermatitis, advancing our understanding in cellular and microbial changes during AD-periodontitis progression.
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Dermatite Atópica , Periodontite , Humanos , Animais , Camundongos , Dermatite Atópica/induzido quimicamente , Dinitroclorobenzeno/metabolismo , Dinitroclorobenzeno/farmacologia , Dinitroclorobenzeno/uso terapêutico , RNA Ribossômico 16S , Imunoglobulina E/metabolismo , Anti-Inflamatórios/farmacologia , Pele , Inflamação/metabolismo , Periodontite/complicações , Periodontite/metabolismo , Camundongos Endogâmicos BALB C , Citocinas/metabolismoRESUMO
The use of microbial electrochemical sensors, with electroactive biofilms (EABs) as sensing elements, is a promising strategy to timely measure the biochemical oxygen demand (BOD) of wastewater. However, accumulation of Coulombic yield over a complete degradation cycle is time-consuming. Therefore, understanding the correlation between current output and EAB metabolism is urgently needed. Here, we recognized a tail stage (TS) on a current-time curve according to current increase rateâa period with the least electron harvesting efficiency. EAB adopted a series of metabolic compensation strategies, including slow metabolism of residual BOD, suspended growth, reduced cell activity, and consumption of carbon storage polymers, to cope with substrate deficiency in TS. The supplementary electrons provided by the decomposition of glycogen and fatty acid polymers increased the Coulombic efficiencies of TS to >100%. The tail current produced by spontaneous metabolic compensation showed a trend of convergent exponential decay, independent of BOD concentration. Therefore, we proposed the TS prediction model (TSPM) to predict Coulombic yield, which shortened BOD measurement time by 96% (to â¼0.5 h) with deviation <4 mg/L when using real domestic wastewater. Our findings on current output in TS give insights into bacterial substrate storage and consumption, as well as regulation in substrate-deficient environment, and provide a basis for developing BOD sensors.
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Técnicas Biossensoriais , Águas Residuárias , Biofilmes , Bactérias/metabolismo , Oxigênio/análise , PolímerosRESUMO
In Escherichia coli, transcription-translation coupling is mediated by NusG. Although chloroplasts are descendants of endosymbiotic prokaryotes, the mechanism underlying this coupling in chloroplasts remains unclear. Here, we report transcription-translation coupling through AtNusG in chloroplasts. AtNusG is localized in chloroplast nucleoids and is closely associated with the chloroplast PEP complex by interacting with its essential component PAP9. It also comigrates with chloroplast ribosomes and interacts with their two components PRPS5 (uS5c) and PRPS10 (uS10c). These data suggest that the transcription and translation machineries are coupled in chloroplasts. In the atnusg mutant, the accumulation of chloroplast-encoded photosynthetic gene transcripts, such as psbA, psbB, psbC and psbD, was not obviously changed, but that of their proteins was clearly decreased. Chloroplast polysomic analysis indicated that the decrease in these proteins was due to the reduced efficiency of their translation in this mutant, leading to reduced photosynthetic efficiency and enhanced sensitivity to cold stress. These data indicate that AtNusG-mediated coupling between transcription and translation in chloroplasts ensures the rapid establishment of photosynthetic capacity for plant growth and the response to environmental changes. Therefore, our study reveals a conserved mechanism of transcription-translation coupling between chloroplasts and E. coli, which perhaps represents a regulatory mechanism of chloroplast gene expression. This study provides insights into the underlying mechanisms of chloroplast gene expression in higher plants.
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Proteínas de Arabidopsis , Arabidopsis , Proteínas de Cloroplastos , Cloroplastos , Arabidopsis/genética , Escherichia coli/genética , Fatores de Alongamento de Peptídeos , Fatores de Transcrição , Proteínas de Cloroplastos/metabolismo , Proteínas de Arabidopsis/metabolismo , Transcrição Gênica , Biossíntese de ProteínasRESUMO
BACKGROUND: The role of adipokines in the development of lung diseases is significant, yet their specific relationship with different lung diseases remains unclear. METHODS: In our research, we analyzed genetic variations associated with adipokines and various lung conditions such as interstitial lung disease, chronic obstructive pulmonary disease, asthma, lung cancer, sleep apnea, pneumonia, and tuberculosis, using data from public genome-wide studies. We employed Mendelian randomization techniques, including inverse variance weighting, weighted median, and MR-Egger regression methods, and conducted sensitivity checks to validate our findings. RESULTS: A study using the FinnGen database, which included 198,955 participants, identified 13 SNPs associated with adiponectin. Notably, adiponectin was found to significantly reduce the risk of interstitial lung disease and idiopathic pulmonary fibrosis. However, little evidence was found to establish a direct cause-effect relationship between the six adipokines and several other lung conditions, including sarcoidosis, asthma, chronic obstructive pulmonary disease, lung cancer, tuberculosis, pneumonia, and sleep apnea syndrome. CONCLUSION: This study reveals a reverse link between adiponectin levels and the likelihood of interstitial lung disease, including idiopathic pulmonary fibrosis.
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Asma , Fibrose Pulmonar Idiopática , Neoplasias Pulmonares , Pneumonia , Doença Pulmonar Obstrutiva Crônica , Síndromes da Apneia do Sono , Tuberculose , Humanos , Adipocinas , Adiponectina , Análise da Randomização MendelianaRESUMO
It remains a significant challenge in prosthetic rehabilitation for combined hard and soft palate defects on account of two primary reasons. At first, conventional impressions can hardly get an accurate analogue and usually bring about a terrible experience for the patients. Secondly, conventional hard denture base resins used in obturator prostheses exhibit limitations in marginal sealing, undercut retention, and elastic buffering when in contact with the soft palate. This article presents a case where combined hard and soft palate defects were successfully and rapidly reconstructed by using digital intraoral impression technology and denture soft reline material.
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Renal clearable nanoparticles have been drawing much attention as they can avoid prolonged accumulation in the body by efficiently clearing through the kidneys. While much effort has been made to understand their interactions within the kidneys, it remains unclear whether their transport could be influenced by other organs, such as the liver, which plays a crucial role in metabolizing and eliminating both endogenous and exogenous substances through various biotransformation processes. Here, by utilizing renal clearable IRDye800CW conjugated gold nanocluster (800CW4-GS18-Au25) as a model, we found that although 800CW4-GS18-Au25 strongly resisted serum-protein binding and exhibited minimal accumulation in the liver, its surface was still gradually modified by hepatic glutathione-mediated biotransformation when passing through the liver, resulting in the dissociation of IRDye800CW from Au25 and biotransformation-generated fingerprint message of 800CW4-GS18-Au25 in urine, which allowed us to facilely quantify its urinary biotransformation index (UBI) via urine chromatography analysis. Moreover, we observed the linear correlation between UBI and hepatic glutathione concentration, offering us a noninvasive method for quantitative detection of liver glutathione level through a simple urine test. Our discoveries would broaden the fundamental understanding of in vivo transport of nanoparticles and advance the development of urinary probes for noninvasive biodetection.
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It remains challenging to comprehensively understand the packing models of conjugated polymers, in which side chains play extremely critical roles. The side chains are typically flexible and non-conductive and are widely used to improve the polymer solubility in organic solutions. Herein, a buffer chain model is proposed to describe link between conjugated backbone and side chains for understanding the relationship of crystallization competition of conductive conjugated backbones and non-conductive side chains. A longer buffer chain is beneficial for alleviating such crystallization competition and further promoting the spontaneous packing of conjugated backbones, resulting in enhanced charge transport properties. Our results provide a novel concept for designing conjugated polymers towards ordered organization and enhanced electronic properties and highlight the importance of balancing the competitive interactions between different parts of conjugated polymers.
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Cumulenes, sp-hybridized carbon motifs featuring consecutive double bonds, have rarely been explored as π-elements for conjugated polymers. Long cumulenic conjugated polymers can serve as models for approaching carbyne, an intriguing yet elusive carbon allotrope. However, their synthesis is notoriously difficult due to intrinsic instability. To date, only few [3]cumulene-based polymers have been synthesized, mostly relying on surface chemistry. Higher cumulene-based polymers remain unknown. Here, we present a "meet in the middle" strategy to overcome this challenge and synthesize high-molecular-weight, stable, and solution-processable conjugated [5]cumulene polymers (Mw up to 67.9 kg/mol). Our approach involves a new polymerization method called step-growth condensation polymerization of propargylic electrophiles (step-growth CPPE). The structures and molecular weights of the cumulenic polymers are established by various spectroscopic methods, including a comparative analysis of a discrete oligomer series. By introducing ortho-substituents on the aryl side groups, we successfully address the stability-conjugation dilemma. Electronic communication between cumulene units is found to be contingent upon the aromaticity of the π-spacers, enabling flexible energy-level adjustment and new narrow band gap polymers. The synthetic methodology and structure-property relationship established in this work serve as the starting points for the exploration of this fascinating family of sp-carbon-rich materials.
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Charge transfer at the semiconductor/solution interface is fundamental to photoelectrocatalytic water splitting. Although insights into charge transfer in the electrocatalytic process can be gained from the phenomenological Butler-Volmer theory, there is limited understanding of interfacial charge transfer in the photoelectrocatalytic process, which involves intricate effects of light, bias, and catalysis. Here, using operando surface potential measurements, we decouple the charge transfer and surface reaction processes and find that the surface reaction enhances the photovoltage via a reaction-related photoinduced charge transfer regime as demonstrated on a SrTiO3 photoanode. We show that the reaction-related charge transfer induces a change in the surface potential that is linearly correlated to the interfacial charge transfer rate of water oxidation. The linear behavior is independent of the applied bias and light intensity and reveals a general rule for interfacial transfer of photogenerated minority carriers. We anticipate the linear rule to be a phenomenological theory for describing interfacial charge transfer in photoelectrocatalysis.
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The room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPb18+xSbTe20 crystals using a vertical Bridgman method. A large weighted mobility of â¼410 cm2 V-1 s-1 is achieved in the AgPb18.4SbTe20 crystal, which is almost 4 times higher than that of the polycrystalline counterpart due to the elimination of grain boundaries and Ag-rich dislocations verified by atom probe tomography, highlighting the significant benefit of growing crystals for low-temperature thermoelectrics. Due to the largely promoted weighted mobility, we achieve a high power factor of â¼37.8 µW cm-1 K-2 and a large figure of merit ZT of â¼0.6 in AgPb18.4SbTe20 crystal at 303 K. We further designed a 7-pair thermoelectric module using this n-type crystal and a commercial p-type (Bi, Sb)2Te3-based material. As a result, a high cooling temperature difference (ΔT) of â¼42.7 K and a power generation efficiency of â¼3.7% are achieved, revealing promising thermoelectric applications for PbTe-based materials near room temperature.