Because of its fundamental importance in many branches of science, hydrogen bonding is a subject of intense contemporary research interest. The physical and chemical properties of hydrogen bonds in ...the ground state have been widely studied both experimentally and theoretically by chemists, physicists, and biologists. However, hydrogen bonding in the electronic excited state, which plays an important role in many photophysical processes and photochemical reactions, has scarcely been investigated. Upon electronic excitation of hydrogen-bonded systems by light, the hydrogen donor and acceptor molecules must reorganize in the electronic excited state because of the significant charge distribution difference between the different electronic states. The electronic excited-state hydrogen-bonding dynamics, which are predominantly determined by the vibrational motions of the hydrogen donor and acceptor groups, generally occur on ultrafast time scales of hundreds of femtoseconds. As a result, state-of-the-art femtosecond time-resolved vibrational spectroscopy is used to directly monitor the ultrafast dynamical behavior of hydrogen bonds in the electronic excited state. It is important to note that the excited-state hydrogen-bonding dynamics are coupled to the electronic excitation. Fortunately, the combination of femtosecond time-resolved spectroscopy and accurate quantum chemistry calculations of excited states resolves this issue in laser experiments. Through a comparison of the hydrogen-bonded complex to the separated hydrogen donor or acceptor in ground and electronic excited states, the excited-state hydrogen-bonding structure and dynamics have been obtained. Moreover, we have also demonstrated the importance of hydrogen bonding in many photophysical processes and photochemical reactions. In this Account, we review our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of electronic excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that the intermolecular hydrogen bond in the electronic excited state is greatly strengthened for coumarin chromophores and weakened for thiocarbonyl chromophores. We have also clarified that the intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced through the regulation of electronic states by hydrogen-bonding interactions. Consequently, the fluorescence of chromophores in hydrogen-bonded surroundings is quenched or enhanced by hydrogen bonds. Our research expands our understanding of the nature of hydrogen bonding by delineating the interaction between hydrogen bonds and photons, thereby providing a basis for excited-state hydrogen bonding studies in photophysics, photochemistry, and photobiology.
Cervical cancer is one of the most common gynecological malignancies, and when detected and treated at an early stage, the cure rate is almost 100%. Colposcopy can be used to diagnose cervical ...lesions by direct observation of the surface of the cervix using microscopic biopsy and pathological examination, which can improve the diagnosis rate and ensure that patients receive fast and effective treatment. Digital colposcopy and automatic image analysis can reduce the work burden on doctors, improve work efficiency, and help healthcare institutions to make better treatment decisions in underdeveloped areas. The present study used a deep‐learning model to classify the images of cervical lesions. Clinicians could determine patient treatment based on the type of cervix, which greatly improved the diagnostic efficiency and accuracy. The present study was divided into two parts. First, convolutional neural networks were used to segment the lesions in the cervical images; and second, a neural network model similar to CapsNet was used to identify and classify the cervical images. Finally, the training set accuracy of our model was 99%, the test set accuracy was 80.1%, it obtained better results than other classification methods, and it realized rapid classification and prediction of mass image data.
The cytokinin oxidase / dehydrogenase (CKX) gene plays a principal role in controlling cyto-kinin levels and has been shown to be a major quantitative trait locus (QTL) affecting grain number in ...rice. However, the function and evaluation of the haplotypes of the wheat CKX gene have yet to be illustrated.
In this study, TaCKX6-D1, a wheat ortholog of rice OsCKX2, was cloned and its haplotype variants were determined to be significantly associated with the 1000-grain weight on the basis of linkage mapping, association analysis and gene expression analysis.
Five TaCKX6-D1 haplotypes, designated a–e, were identified. An indel marker was developed to identify haplotype a, which was associated with higher grain weight. Haplotype a showed decreased expression relative to haplotype b in seeds at 8 d after pollination. Sequence variations among modern cultivars, landraces and wild species suggest a significant domestication signature at the TaCKX6-D1 locus in Chinese wheat germplasm.
TaCKX6-D1 may serve as a useful gene for the breeding of high-yielding wheat. A strategy for allele mining and utilization of TaCKX6-D1 was proposed. Our study also sheds light on the mechanisms of grain development and domestication of wheat, as well as the functional divergence of orthologs in comparative genomics.
The time-dependent density functional theory (TDDFT) method was carried out to investigate the hydrogen-bonded intramolecular charge-transfer (ICT) excited state of 4-dimethylaminobenzonitrile ...(DMABN) in methanol (MeOH) solvent. We demonstrated that the intermolecular hydrogen bond Cidentical withN···H---O formed between DMABN and MeOH can induce the Cidentical withN stretching mode shift to the blue in both the ground state and the twisted intramolecular charge-transfer (TICT) state of DMABN. Therefore, the two components at 2091 and 2109 cm⁻¹ observed in the time-resolved infrared (TRIR) absorption spectra of DMABN in MeOH solvent were reassigned in this work. The hydrogen-bonded TICT state should correspond to the blue-side component at 2109 cm⁻¹, whereas not the red-side component at 2091 cm⁻¹ designated in the previous study. It was also demonstrated that the intermolecular hydrogen bond Cidentical withN···H---O is significantly strengthened in the TICT state. The intermolecular hydrogen bond strengthening in the TICT state can facilitate the deactivation of the excited state via internal conversion (IC), and thus account for the fluorescence quenching of DMABN in protic solvents. Furthermore, the dynamic equilibrium of these electronically excited states is explained by the hydrogen bond strengthening in the TICT state.
Shifting H bonds: Concerted hydrogen‐bond strengthening and weakening in different excited states can tune energy gaps between low‐lying electronic states and thus account for the photochemistry of ...thiocarbonyl chromophores in alcoholic solutions (see picture). Also, the relationship between electronic spectral shifts and the electronic excited‐state hydrogen‐bonding changes is clarified.
A signal-on photoelectrochemical (PEC) immunosensor was constructed for detecting tumor marker in this work. α-fetoprotein (AFP) was chosen as a model analyte to investigate the prepared procedure ...and the analytical performance of the exploited sensor. In order to construct the sensor, CdSe QDs were used as photoactive material, biotin conjugated AFP antibody (Bio-anti-AFP) as detecting probe, streptavidin (SA) as signal capturing unit, biotin functionalized apoferritin encapsulated ascorbic acid (Bio-APOAA) as amplification unit, which were assembled onto the electrodes. The sensing strategy was based on in situ enzymatic hydrolysis of Bio-APOAA to release ascorbic acid (AA) as sacrificial electron donor to produce photocurrent. The photocurrent from the immunosensor was monitored as a result of AFP concentrations. The constructed sensing platform displayed high selectivity and good sensitivity for detecting AFP. Under optimal conditions, a wide linear range from 0.001 to 1000ng/mL and a low detection limit of 0.31pg/mL were obtained. The developed immunosensor is expected to be used to determine AFP and other tumor markers in human plasma in clinical laboratories either for pre-cancer screening or cancer monitoring. Moreover, this sensing platform further has the potential to use for the detection of trypsin activity and the corresponding inhibitor-screening.
•A signal-on photoelectrochemical immunosensor for detecting AFP was developed.•Its sensing strategy was based on in situ enzymatic hydrolysis to release ascorbic acid as sacrificial electron donor.•The limit of detection for AFP is low down to 0.31pg/mL.
The lung is the primary organ targeted by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), making respiratory failure a leading coronavirus disease 2019 (COVID-19)-related mortality. ...However, our cellular and molecular understanding of how SARS-CoV-2 infection drives lung pathology is limited. Here we constructed multi-omics and single-nucleus transcriptomic atlases of the lungs of patients with COVID-19, which integrate histological, transcriptomic and proteomic analyses. Our work reveals the molecular basis of pathological hallmarks associated with SARS-CoV-2 infection in different lung and infiltrating immune cell populations. We report molecular fingerprints of hyperinflammation, alveolar epithelial cell exhaustion, vascular changes and fibrosis, and identify parenchymal lung senescence as a molecular state of COVID-19 pathology. Moreover, our data suggest that FOXO3A suppression is a potential mechanism underlying the fibroblast-to-myofibroblast transition associated with COVID-19 pulmonary fibrosis. Our work depicts a comprehensive cellular and molecular atlas of the lungs of patients with COVID-19 and provides insights into SARS-CoV-2-related pulmonary injury, facilitating the identification of biomarkers and development of symptomatic treatments.
The interferon-regulatory factor (IRF) family comprises nine members in mammals. Although this transcription factor family was originally thought to function primarily in the immune system, ...contributing to both the innate immune response and the development of immune cells, recent advances have revealed that IRFs plays critical roles in other biological processes, such as metabolism. Accordingly, abnormalities in the expression and/or function of IRFs have increasingly been linked to disease. Herein, we provide an update on the recent progress regarding the regulation of immune responses and immune cell development associated with IRFs. Additionally, we discuss the relationships between IRFs and immunity, metabolism, and disease, with a particular focus on the role of IRFs as stress sensors. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.
•IRFs are involved not only in immunity, but also in metabolism, and related diseases.•The roles of IRFs in cardiovascular and cerebrovascular diseases are discussed.•IRFs are stress sensors.
In this work, we fabricated and systematically investigated the mechanical and microwave absorption properties of multi‐walled carbon nanotube (MWCNT)—glass fiber (GF)—epoxy composites. The ...composites showed high electromagnetic (EM) wave absorption performance in a wide frequency range. The maximum reflection loss of the composites can reach to −48 dB at 24.5 GHz. The EM wave absorption of the composites strongly depends on MWCNT and GF contents and can reach to ~70% at 26.5 GHz; further, such dependence is peculiar, contradicting to the conventional wisdom, due to high density interfaces in the materials, which lead to multiple scatterings and multiple absorptions of EM waves. The tensile strength of the composites was enhanced to ~427 MPa with ~74 wt% GFs, that is comparable to that of commercial Al alloy 6061 (~300 MPa, but not much EM wave absorption). The composites have the potential as multifunctional microwave absorption and low‐weight structural materials without a need of additional coating.
In crop plants, a high-density genetic linkage map is essential for both genetic and genomic researches. The complexity and the large size of wheat genome have hampered the acquisition of a ...high-resolution genetic map. In this study, we report a high-density genetic map based on an individual mapping population using the Affymetrix Wheat660K single-nucleotide polymorphism (SNP) array as a probe in hexaploid wheat. The resultant genetic map consisted of 119 566 loci spanning 4424.4 cM, and 119 001 of those loci were SNP markers. This genetic map showed good collinearity with the 90 K and 820 K consensus genetic maps and was also in accordance with the recently released wheat whole genome assembly. The high-density wheat genetic map will provide a major resource for future genetic and genomic research in wheat. Moreover, a comparative genomics analysis among gramineous plant genomes was conducted based on the high-density wheat genetic map, providing an overview of the structural relationships among theses gramineous plant genomes. A major stable quantitative trait locus (QTL) for kernel number per spike was characterized, providing a solid foundation for the future high-resolution mapping and map-based cloning of the targeted QTL.
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