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1.
J Integr Plant Biol ; 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38953746

ABSTRACT

Aporphine alkaloids have diverse pharmacological activities; however, our understanding of their biosynthesis is relatively limited. Previous studies have classified aporphine alkaloids into two categories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each category. In this study, we identified two specific cytochrome P450 enzymes (CYP80G6 and CYP80Q5) with distinct activities toward (S)-configured and (R)-configured substrates from the herbaceous perennial vine Stephania tetrandra, shedding light on the biosynthetic mechanisms and stereochemical features of these two aporphine alkaloid categories. Additionally, we characterized two CYP719C enzymes (CYP719C3 and CYP719C4) that catalyzed the formation of the methylenedioxy bridge, an essential pharmacophoric group, on the A- and D-rings, respectively, of aporphine alkaloids. Leveraging the functional characterization of these crucial cytochrome P450 enzymes, we reconstructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast (Saccharomyces cerevisiae) for the de novo production of compounds such as (R)-glaziovine, (S)-glaziovine, and magnoflorine. This study provides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.

2.
J Med Chem ; 2024 Jun 24.
Article in English | MEDLINE | ID: mdl-38912577

ABSTRACT

Aberrant activation of the Wnt/ß-catenin signaling is associated with tumor development, and blocking ß-catenin/BCL9 is a novel strategy for oncogenic Wnt/ß-catenin signaling. Herein, we presented two novel ß-catenin variations and exposed conformational dynamics in several ß-catenin crystal structures at the BCL9 binding site. Furthermore, we identified a class of novel urea-containing compounds targeting ß-catenin/BCL9 interaction. Notably, the binding modalities of inhibitors were greatly affected by the conformational dynamics of ß-catenin. Among them, 28 had a strong affinity for ß-catenin (Kd = 82 nM), the most potent inhibitor reported. In addition, 13 and 35 not only activate T cells but also promote the antigen presentation of cDC1, showing robust antitumor efficacy in the CT26 model. Collectively, our study demonstrated a series of potent small-molecule inhibitors targeting ß-catenin/BCL9, which can enhance antigen presentation and activate cDC1 cells, delivering a potential strategy for boosting innate and adaptive immunity to overcome immunotherapy resistance.

3.
Front Vet Sci ; 11: 1359421, 2024.
Article in English | MEDLINE | ID: mdl-38840631

ABSTRACT

Porcine circovirus disease (PCV) causes substantial economic losses in the pig industry, primarily from porcine circovirus type 2 (PCV2) and porcine circovirus type 3 (PCV3). Novel vaccines are necessary to prevent and control PCV infections. PCV coat proteins are crucial for eliciting immunogenic proteins that induce the production of antibodies and immune responses. A vaccine platform utilizing Semliki Forest virus RNA replicons expressing vesicular stomatitis virus glycoprotein (VSV-G), was recently developed. This platform generates virus-like vesicles (VLVs) containing VSV-G exclusively, excluding other viral structural proteins. In our study, we developed a novel virus-like vesicle vaccine by constructing recombinant virus-like vesicles (rVLVs) that also express EGFP. These rVLVs were created using the RNA replicon of Venezuelan equine encephalomyelitis (VEEV) and New Jersey serotype VSV-G. The rVLVs underwent characterization and safety evaluation in vitro. Subsequently, rVLVs expressing PCV2d-Cap and PCV3-Cap proteins were constructed. Immunization of C57 mice with these rVLVs led to a significant increase in anti-porcine circovirus type 2 and type 3 capsid protein antibodies in mouse serum. Additionally, a cellular immune response was induced, as evidenced by high production of IFN-γ and IL-4 cytokines. Overall, this study demonstrates the feasibility of developing a novel porcine circovirus disease vaccine based on rVLVs.

4.
J Med Chem ; 2024 Jun 24.
Article in English | MEDLINE | ID: mdl-38913996

ABSTRACT

Clinical and biological studies have shown that overexpression of BFL-1 is one contributing factor to venetoclax resistance. The resistance might be overcome by a potent BFL-1 inhibitor, but such an inhibitor is rare. In this study, we show that 56, featuring an acrylamide moiety, inhibited the BFL-1/BID interaction with a Ki value of 105 nM. More interestingly, 56 formed an irreversible conjugation adduct at the C55 residue of BFL-1. 56 was a selective BFL-1 inhibitor, and its MCL-1 binding affinity was 10-fold weaker, while it did not bind BCL-2 and BCL-xL. Mechanistic studies showed that 56 overcame venetoclax resistance in isogenic AML cell lines MOLM-13-OE and MV4-11-OE, which both overexpressed BFL-1. More importantly, 56 and venetoclax combination promoted stronger apoptosis induction than either single agent. Collectively, our data show that 56 overcame resistance to venetoclax in AML cells overexpressing BFL-1. These attributes make 56 a promising candidate for future optimization.

5.
J Phys Chem Lett ; 15(23): 6099-6107, 2024 Jun 13.
Article in English | MEDLINE | ID: mdl-38820592

ABSTRACT

Understanding the nonlinear response of light and materials is crucial for fundamental physics and next-generation electronic devices. In this work, we have investigated the second-order nonlinear bulk photovoltaic (BPV) and bulk spin photovoltaic (BSPV) effects in the piezoelectric binary materials T-IV-VI and T-V-V (IV = Ge, Sn; VI = S, Se; and V = P, As, Sb, Bi). The independent nonzero conductivity tensors of charge current are derived for these binaries through the symmetry analysis, along with the mechanism for generating pure spin current. These binaries, with their unique folded structure, exhibit significant charge and spin currents under illumination. Furthermore, we find that strain engineering can effectively modulate charge/spin currents by influencing charge density distribution and built-in electric field due to the piezoelectric effect. Our research suggests that the piezoelectric binary materials possess enormous and tunable charge/spin currents, underscoring their potential for applications in nonlinear flexible optoelectronics and spintronics.

6.
RSC Adv ; 14(21): 14894-14903, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38720977

ABSTRACT

The use of mixed halide perovskites in the preparation of blue light-emitting diodes (LEDs) is considered to be the most effective and direct approach. However, the introduction of chlorine (Cl) element might raise stability issues in the system and lead to low efficiency, thereby impeding the development of deep blue light-emitting diodes with high efficiency and stability. Determining the alloy concentration and the atomic distribution of bromine-chlorine (Br-Cl) mixed systems is essential for further application of deep blue light-emitting diodes. In this work, we have systematically investigated the stability of bromine-chlorine (Br-Cl) mixed alloy systems in various substitution configurations using high-throughput theoretical calculations. Based on this, we have examined the relationship between configuration stability and three aspects: the type of octahedra, the orientation of the octahedra and the Pb-X-Pb distortion angle in the configuration.

7.
BMC Biotechnol ; 24(1): 20, 2024 Apr 18.
Article in English | MEDLINE | ID: mdl-38637734

ABSTRACT

BACKGROUND: Obtaining high-quality chloroplast genome sequences requires chloroplast DNA (cpDNA) samples that meet the sequencing requirements. The quality of extracted cpDNA directly impacts the efficiency and accuracy of sequencing analysis. Currently, there are no reported methods for extracting cpDNA from Erigeron breviscapus. Therefore, we developed a suitable method for extracting cpDNA from E. breviscapus and further verified its applicability to other medicinal plants. RESULTS: We conducted a comparative analysis of chloroplast isolation and cpDNA extraction using modified high-salt low-pH method, the high-salt method, and the NaOH low-salt method, respectively. Subsequently, the number of cpDNA copies relative to the nuclear DNA (nDNA ) was quantified via qPCR. As anticipated, chloroplasts isolated from E. breviscapus using the modified high-salt low-pH method exhibited intact structures with minimal cell debris. Moreover, the concentration, purity, and quality of E. breviscapus cpDNA extracted through this method surpassed those obtained from the other two methods. Furthermore, qPCR analysis confirmed that the modified high-salt low-pH method effectively minimized nDNA contamination in the extracted cpDNA. We then applied the developed modified high-salt low-pH method to other medicinal plant species, including Mentha haplocalyx, Taraxacum mongolicum, and Portulaca oleracea. The resultant effect on chloroplast isolation and cpDNA extraction further validated the generalizability and efficacy of this method across different plant species. CONCLUSIONS: The modified high-salt low-pH method represents a reliable approach for obtaining high-quality cpDNA from E. breviscapus. Its universal applicability establishes a solid foundation for chloroplast genome sequencing and analysis of this species. Moreover, it serves as a benchmark for developing similar methods to extract chloroplast genomes from other medicinal plants.


Subject(s)
Genome, Chloroplast , Plants, Medicinal , DNA, Chloroplast/genetics , Plants, Medicinal/genetics , Chloroplasts/genetics , Chromosome Mapping , Phylogeny
8.
Eur J Med Chem ; 270: 116366, 2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38581730

ABSTRACT

Inhibition of MDM2/p53 interaction with small-molecule inhibitors stabilizes p53 from MDM2 mediated degradation, which is a promising strategy for the treatment of cancer. In this report, a novel series of 4-imidazolidinone-containing compounds have been synthesized and tested in MDM2/p53 and MDM4/p53 FP binding assays. Upon SAR studies, compounds 2 (TB114) and 22 were identified as the most potent inhibitors of MDM2/p53 but not MDM4/p53 interactions. Both 2 and 22 exhibited strong antiproliferative activities in HCT-116 and MOLM-13 cell lines harboring wild type p53. Mechanistic studies show that 2 and 22 dose-dependently activated p53 and its target genes and induced apoptosis in cells based on the Western blot, qPCR, and flow cytometry assays. In addition, the antiproliferative activities of 2 and 22 were dependent on wild type p53, while they were not toxic to HEK-293 kidney cells. Furthermore, the on-target activities of 2 were general and applicable to other cancer cell lines with wild type p53. These attributes make 2 a good candidate for future optimization to discover a potential treatment of wild-type p53 cancer.


Subject(s)
Antineoplastic Agents , Tumor Suppressor Protein p53 , Humans , Tumor Suppressor Protein p53/metabolism , Proto-Oncogene Proteins c-mdm2/metabolism , HEK293 Cells , Cell Line, Tumor , Apoptosis , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Proto-Oncogene Proteins/metabolism , Cell Cycle Proteins/metabolism
9.
RSC Adv ; 14(12): 8293-8302, 2024 Mar 06.
Article in English | MEDLINE | ID: mdl-38469193

ABSTRACT

In this paper, the SiCN(Ni)/BN ceramic with excellent electromagnetic wave (EMW) absorption performance was successfully prepared. The Ni and Ni3Si were in situ formed by the introduction of nickel acetylacetonate (NA), which effectively improved the impedance matching performance of SiCN(Ni)/BN ceramics. The EMW absorption properties of the SiCN(Ni)/BN ceramics showed a trend of first increasing and then decreasing with the increase in content of NA. When the NA content reached 7 wt%, the impedance matching range of SiCN-7 was optimal. The minimum reflection loss (RLmin) of SiCN-7 reached -53.47 dB at 4.2 mm and the effective absorption bandwidth (EAB) was 2.32 GHz at 3.48 mm. Through the analysis of electrical conductivity, it was found that the proportion of polarization loss in dielectric loss was more than 99%. It is worth noting that the radar cross section (RCS) value of SiCN-7 absorber was lower than that of the perfect electrical conductor (PEC) plate in the range of -90-90°, and showed a larger coverage angle, indicating that it possessed a good practical application prospect in the field of electromagnetic wave absorption.

10.
Poult Sci ; 103(6): 103639, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38547673

ABSTRACT

Riemerella anatipestifer, belonging to Weeksellaceae family Riemerella, is a bacterium that can infect ducks, geese, and turkeys, causing diseases known as duck infectious serositis, new duck disease, and duck septicemia. We collected diseased materials from ducks on a duck farm in China and then isolated and purified a strain of serotype 1 R. anatipestifer named SX-1. Animal experiments showed that SX-1 is a highly virulent strain with an LD50 value of 101 CFU/mL. The complete genome sequence was obtained. The complete genome sequence of R. anatipestifer SX-1 was 2,112,539 bp; 847 genes were involved in catalytic activity, and 445 genes were related to the cell membrane. The total length of the repetitive sequences was 8746 bp. Four CRISPR loci were predicted in R. anatipestifer strain SX-1, and 4 genomic islands were predicted. Concentration and ultra-high-speed centrifugation were used to extract the outer membrane vesicles of R. anatipestifer SX-1. The OMVs were extracted successfully. Particle size analysis revealed the size and abundance of particles: 147.4 nm, 94.9%; 293.6 nm, 1.1%; 327.2 nm, 1.1%; 397.2 nm, 0.3%; and 371.8 nm, 1.1%. The average size was 173.5 nm. Label-free proteomic technology was used to identify proteins in the outer membrane vesicles. ATCC 11845 served as the reference genome sequence, and 148 proteins were identified using proteomic analysis, which were classified into 5 categories based on their sources. Among them, 24 originated from cytoplasmic proteins, 4 from extracellular secreted proteins, 27 from outer membrane proteins, 10 from periplasmic proteins, and 83 from unknown sources. This study conducted a proteomic analysis of OMVs to provide a theoretical basis for the development of R. anatipestifer OMVs vaccines and adjuvants and lays the foundation for further research on the relationship between the pathogenicity of R. anatipestifer and OMVs.


Subject(s)
Ducks , Poultry Diseases , Proteomics , Riemerella , Riemerella/genetics , Poultry Diseases/microbiology , Animals , Flavobacteriaceae Infections/veterinary , Flavobacteriaceae Infections/microbiology , Proteome , Bacterial Outer Membrane
12.
Vet Res Commun ; 48(3): 1879-1889, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38349546

ABSTRACT

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogens affecting the swine industry. In this report, a novel PRRSV strain SXht2012 was isolated from Shanxi province in China. To identify genetic characteristics of SXht2012, we conducted phylogenetic and homology analyses after sequencing its complete genome. The results revealed that SXht2012 belonged to NADC30-like strain and shared 91.3% nucleotide (nt) identity with strain NADC30. Notably, sequence alignment showed that a distinctive feature in the NSP2 region, where a 131-amino acid (aa) deletion was found in the hypervariable region (HVR). Additionally, variations were also detected in the GP5 protein, specifically in the decoy peptide, T cell peptide, and a potential glycosylation site (aa 32). Furthermore, we also found that SXht2012 was likely a recombination virus originating from NADC30-like and JXA1-like strains, and three recombination breakpoints were identified in the genome at nt positions 1516, 5280 and 6851, which correspond to the NSP2, NSP3, and NSP7 regions. Overall, these findings have significant implications for understanding the genetic variation and evolutionary dynamics of PRRSV strains.


Subject(s)
Phylogeny , Porcine Reproductive and Respiratory Syndrome , Porcine respiratory and reproductive syndrome virus , Porcine respiratory and reproductive syndrome virus/genetics , Animals , China , Swine , Porcine Reproductive and Respiratory Syndrome/virology , Genome, Viral , Amino Acid Sequence
13.
J Med Chem ; 67(2): 1079-1092, 2024 Jan 25.
Article in English | MEDLINE | ID: mdl-38166388

ABSTRACT

The DNA-encoded library (DEL) is a powerful hit generation tool for chemical biology and drug discovery; however, the optimization of DEL hits remained a daunting challenge for the medicinal chemistry community. In this study, hit compounds targeting the WIN binding domain of WDR5 were discovered by the initial three-cycle linear DEL selection, and their potency was further enhanced by a cascade DEL selection from the focused DEL designed based on the original first run DEL hits. As expected, these new compounds from the second run of focused DEL were more potent WDR5 inhibitors in the protein binding assay confirmed by the off-DNA synthesis. Interestingly, selected inhibitors exhibited good antiproliferative activity in two human acute leukemia cell lines. Taken together, this new cascade DEL selection strategy may have tremendous potential for finding high-affinity leads against WDR5 and provide opportunities to explore and optimize inhibitors for other targets.


Subject(s)
DNA , Drug Discovery , Humans , Gene Library , Protein Binding , DNA/metabolism , Intracellular Signaling Peptides and Proteins/metabolism
14.
Quant Imaging Med Surg ; 14(1): 111-122, 2024 Jan 03.
Article in English | MEDLINE | ID: mdl-38223079

ABSTRACT

Background: Patients with lymphoma receive multiple positron emission tomography/computed tomography (PET/CT) exams for monitoring of the therapeutic response. With PET imaging, a reduced level of injected fluorine-18 fluorodeoxyglucose ([18F]FDG) activity can be administered while maintaining the image quality. In this study, we investigated the efficacy of applying a deep learning (DL) denoising-technique on image quality and the quantification of metabolic parameters and Deauville score (DS) of a low [18F]FDG dose PET in patients with lymphoma. Methods: This study retrospectively enrolled 62 patients who underwent [18F]FDG PET scans. The low-dose (LD) data were simulated by taking a 50% duration of routine-dose (RD) PET list-mode data in the reconstruction, and a U-Net-based denoising neural network was applied to improve the images of LD PET. The visual image quality score (1 = undiagnostic, 5 = excellent) and DS were assessed in all patients by nuclear radiologists. The maximum, mean, and standard deviation (SD) of the standardized uptake value (SUV) in the liver and mediastinum were measured. In addition, lesions in some patients were segmented using a fixed threshold of 2.5, and their SUV, metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) were measured. The correlation coefficient and limits of agreement between the RD and LD group were analyzed. Results: The visual image quality of the LD group was improved compared with the RD group. The DS was similar between the RD and LD group, and the negative (DS 1-3) and positive (DS 4-5) results remained unchanged. The correlation coefficients of SUV in the liver, mediastinum, and lesions were all >0.85. The mean differences of SUVmax and SUVmean between the RD and LD groups, respectively, were 0.22 [95% confidence interval (CI): -0.19 to 0.64] and 0.02 (95% CI: -0.17 to 0.20) in the liver, 0.13 (95% CI: -0.17 to 0.42) and 0.02 (95% CI: -0.12 to 0.16) in the mediastinum, and -0.75 (95% CI: -3.42 to 1.91), and -0.13 (95% CI: -0.57 to 0.31) in lesions. The mean differences in MTV and TLG were 0.85 (95% CI: -2.27 to 3.98) and 4.06 (95% CI: -20.53 to 28.64) between the RD and LD groups. Conclusions: The DL denoising technique enables accurate tumor assessment and quantification with LD [18F]FDG PET imaging in patients with lymphoma.

15.
Cancer Sci ; 115(3): 763-776, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38243657

ABSTRACT

Hepatocellular carcinoma (HCC) does not respond well to current treatments, even immune checkpoint inhibitors. PD-L1 (programmed cell death ligand 1 or CD274 molecule)-mediated immune escape of tumor cells may be a key factor affecting the efficacy of immune checkpoint inhibitor (ICI) therapy. However, the regulatory mechanisms of PD-L1 expression and immune escape require further exploration. Here, we observed that DDX1 (DEAD-box helicase 1) was overexpressed in HCC tissues and associated with poor prognosis in patients with HCC. Additionally, DDX1 expression correlated negatively with CD8+ T cell frequency. DDX1 overexpression significantly increased interferon gamma (IFN-γ)-mediated PD-L1 expression in HCC cell lines. DDX1 overexpression decreased IFN-γ and granzyme B production in CD8+ T cells and inhibited CD8+ T cell cytotoxic function in vitro and in vivo. In conclusion, DDX1 plays an essential role in developing the immune escape microenvironment, rendering it a potential predictor of ICI therapy efficacy in HCC.


Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Humans , B7-H1 Antigen/metabolism , Carcinoma, Hepatocellular/metabolism , CD8-Positive T-Lymphocytes , DEAD-box RNA Helicases/metabolism , Interferon-gamma/metabolism , Liver Neoplasms/metabolism , Tumor Microenvironment
16.
Skeletal Radiol ; 53(8): 1651-1656, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38231261

ABSTRACT

Primary malignant bone tumors of the spine are exceedingly rare, with solitary bone plasmacytoma (SBP) representing approximately 30% of all cases. Radiological assessments are crucial for localizing SBP and for ruling out a diagnosis of multiple myeloma (MM). Imaging features resembling a "mini-brain" appear to be distinctive for SBP. Vertebral lesions accompanied by adjacent disc space involvement typically suggest spinal infections, while the potential for SBP involvement is often overlooked. We present a case of a 61-year-old female with SBP who exhibited thoraco-lumbar spine destruction and adjacent disc space involvement. The patient sought treatment at our medical center due to lumbodorsal pain radiating bilaterally to the inguinal regions. Radiological findings revealed an osteolytic lesion involving the intervertebral disc, making it challenging to distinguish between tumor and inflammation. A biopsy of the vertebral lesion confirmed the diagnosis of SBP, which was further supported by laboratory results. Post-diagnosis, the patient underwent radiotherapy, receiving a total dose of 4000 Gy, which alleviated her symptoms. We also provide a comprehensive literature review on SBP with disc involvement to aid both clinical and radiological diagnoses.


Subject(s)
Magnetic Resonance Imaging , Plasmacytoma , Spinal Neoplasms , Humans , Female , Middle Aged , Plasmacytoma/diagnostic imaging , Spinal Neoplasms/diagnostic imaging , Diagnosis, Differential , Magnetic Resonance Imaging/methods , Intervertebral Disc/diagnostic imaging , Intervertebral Disc/pathology , Tomography, X-Ray Computed , Thoracic Vertebrae/diagnostic imaging , Thoracic Vertebrae/pathology , Lumbar Vertebrae/diagnostic imaging , Biopsy
17.
Phys Chem Chem Phys ; 26(3): 2093-2100, 2024 Jan 17.
Article in English | MEDLINE | ID: mdl-38131363

ABSTRACT

Semiconductor materials of abnormal stoichiometric ratio often exhibit unique properties, yet it is still a challenge to determine the structures of such materials in an efficient way. Herein, we propose a method for structurally biased screening according to the coordination numbers and the numbers of Wyckoff positions, balancing the atom local environment and the global symmetry of structures. Based on first-principles calculations, we have predicted two metastable peroxides P21/c-ScO2 and Pmmn-TiO3 with more than six coordination points. For these two structures, the most stable intrinsic defect is the oxygen vacancy (VO) at the peroxide anion (O2-2), which induces the absence of antibonding orbital formed by O2-2 near the valence band maximum. With the introduction of VO, the decrease of coordination numbers leads to charge recombination, and results in the appearance of an ordered phase TiO2.5 with stronger Ti-O orbital hybridization. The proposed method presents a promising and feasible approach for the screening of novel compounds.

18.
J Med Chem ; 66(24): 16991-17025, 2023 12 28.
Article in English | MEDLINE | ID: mdl-38062557

ABSTRACT

MDM2 and MDM4 cooperatively and negatively regulate p53, while this pathway is often hijacked by cancer cells in favor of their survival. Blocking MDM2/p53 interaction with small-molecule inhibitors liberates p53 from MDM2 mediated degradation, which is an attractive strategy for drug discovery. We reported herein structure-based discovery of highly potent spiroindoline-containing MDM2 inhibitor (-)60 (JN122), which also exhibited moderate activities against MDM4/p53 interactions. In a panel of cancer cell lines harboring wild type p53, (-)60 efficiently promoted activation of p53 and its target genes, inhibited cell cycle progression, and induced cell apoptosis. Interestingly, (-)60 also promoted degradation of MDM4. More importantly, (-)60 exhibited good PK properties and exerted robust antitumor efficacies in a systemic mouse xenograft model of MOLM-13. Taken together, our study showcases a class of potent MDM2 inhibitors featuring a novel spiro-indoline scaffold, which is promising for future development targeting cancer cells with wild-type p53.


Subject(s)
Antineoplastic Agents , Neoplasms , Humans , Mice , Animals , Proto-Oncogene Proteins c-mdm2/metabolism , Tumor Suppressor Protein p53/metabolism , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Neoplasms/drug therapy , Apoptosis , Cell Line, Tumor , Proto-Oncogene Proteins/metabolism , Cell Cycle Proteins/metabolism
19.
J Acoust Soc Am ; 154(5): 3041-3051, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37955568

ABSTRACT

The sound absorption coefficient (SAC) of materials measured in a reverberation room is affected by both the intrinsic properties of the material and geometrical dimensions of the sample. A different size of the same material may produce a different SAC primarily due to the edge effect phenomenon. In this research, the experimental data from multiple laboratories was analyzed to evaluate the influence of the edge effect. An empirical function was established based on these measurement data and the linear relationship between the SAC and the relative edge length. Thomasson's method, the two geometric methods, and the analytical method were used to estimate the SAC of an absorber from measurements on a different size sample and compared with results obtained using the empirical function. The results show that the proposed empirical method is a reliable way to predict the SAC of a sample from measurements on a different size sample of the same material, which only requires the thickness, density, and size of the material.

20.
J Am Chem Soc ; 2023 Nov 06.
Article in English | MEDLINE | ID: mdl-37932216

ABSTRACT

The octet rule is a fundamental theory in the chemical bonding of main-group elements, which achieve stable configurations by gaining, losing, or sharing electrons. However, the conventional octet rule, as depicted through Lewis structures, is inadequate for describing the electron delocalization in boron allotropes and boron-rich compounds due to the electron deficiency of boron. To address this, we introduce the concept of fractional electron occupancies, which more accurately reflect the electron delocalization in boron systems. Based on this, we propose a generalized octet rule that provides a more comprehensive understanding of the complex bonding configurations in boron allotropes and boron-rich compounds. Importantly, our predictions for α-B12 are validated by both first-principles calculations and existing experimental data. Beyond boron, this generalized octet rule is also applicable to systems with multiple resonance structures.

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