Search

The structures and nonlinear optical properties of a novel class of alkali metals doped electrides B12N12-M (M = Li, Na, K) were investigated by ab initio quantum chemistry method. The doping of alkali atoms was found to narrow the energy gap values of B12N12 in the range 3.96-6.70 eV. Furthermore, these alkali metals doped compounds with diffuse excess electron exhibited significantly large first hyperpolarizabilities ( β0) as follows: 5571-9157 au for B12N12-Li, 1537-18,889 au for B12N12-Na, and 2803-11,396 au for B12N12-K. Clearly, doping of the alkali atoms could dramatically increase the β0 value of B12N12 ( β0 = 0). Furthermore, their transition energies (Δ E) were also calculated. The results showed that these compounds had low Δ E values in the range 1.407-2.363 eV, which was attributed to large β0 values of alkali metals doped B12N12 nanocage. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A novel complex of cobalt picrate with 2, 6-bis(benzimidazol-2-yl)pyridine (L), has been prepared and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space groupc2/cwitha= 21.8756(6) Å,b= 12.2995(3) Å,c= 27.4827(7) Å,β= 95.6060(10)°, andZ= 4. The structure was refined to the finalR1= 0.0708. The complex units are linked by π-π interactions and hydrogen bonds to give infinite two-dimensional (2-D) supramolecular layers, which are further linked by the intermolecular hydrogen bonds to form a three-dimensional (3-D) netlike supramolecule. [ABSTRACT FROM AUTHOR]

[Display omitted] • Replacing one carbon of benzene-substituted graphdiyne with a B/N atom narrow the HOMO-LUMO gap. • Replacement improves the NLO response in several compounds. • The β 0 values of most of N -substituted compounds are larger than the corresponding B-substituted compounds. • Large-scale distribution of first hyperpolarizability density leads to a larger β 0. A series of B/N-substituted benzene-substituted graphdiyne fragments (1) were studied in detail by density functional theory to evaluate their electronic structures and nonlinear optical (NLO) properties. Substituting a B (N) atom for a C atom introduces extra holes (electrons) in the electronic structure of the compound. The introduction of the N atom can effectively narrow the large energy gap of the 1 , but the value for the B-substituted system does not change significantly. Such compounds show superior NLO response with respect to pristine 1 , and the static first hyperpolarizability (β 0) values of most of N-substituted compounds are larger than the corresponding B-substituted compounds. Moreover, the result of static β 0 of the system can be deeply understood by the distribution of first hyperpolarizability density. These fascinating findings can provide valuable insights for the development of potential high-performance NLO nanomaterials. [ABSTRACT FROM AUTHOR]

The electrical properties and nonlinear optical (NLO) properties of black phosphorus quantum dots (BPQDs) upon doping of alkali and alkaline-earth metal atoms, M@BPQDs (M = Li, Na, K, Be, Mg, and Ca), were systematically investigated based on density functional theory (DFT) method. The results showed that the introduction of metal atoms M could efficiently narrow the wide gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the pristine BPQDs in the range of 2.254–3.098 eV. More importantly, the metal atom M doping can remarkably enhance the second hyperpolarizability (γ 0) of BPQDs, due to electron transfer from M to BPQDs. M@BPQDs possess large second hyperpolarizabilities (γ 0) in the range of 0.81 × 10−33–3.94 × 10−33 esu, where the alkali-doped complexes are much superior to the alkaline-earth-doped complexes. Furthermore, doping heavier K atom on the large-sized BPQDs can obtain the largest γ 0 value of 3.94 × 10−33 esu, which can be understood by its large amplitude distribution of second hyperpolarizability density. Configuration interaction singles (CIS) calculations were performed to get crucial excited states to account for the large γ 0 values. The second hyperpolarizability trend estimated from the two-level formula and DFT calculations correlates nicely. These metal-doped complexes have the deep-ultraviolet (deep-UV) transparent region at wavelength ≤ 200 nm, and hence are new deep-UV NLO molecules. These striking results designate such doped BPQDs as excellent candidates for their potential applications in optical devices. The type of metal atom and the size of BPQDs have a great influence on the second-order NLO response of M@BPQDs. [Display omitted] • The introductions of the metal atoms can narrow the HOMO-LUMO gap of BPQDs. • All the metal-doped complexes show larger γ 0 values as compared to pure BPQDs. • Large-scale distribution of second hyperpolarizability density leads to a larger γ 0. • Absorption spectra shows that complexes can be used as deep-UV NLO materials. [ABSTRACT FROM AUTHOR]

The Chinese pepper (Zanthoxylum simulans) is a flowering plant in the family Rutaceae, native to eastern China and Taiwan. Like many other members of the Rutaceae, it is an economically important aromatic crop known for its volatile oil and nutrition. We determined the complete chloroplast genome sequences for Z. simulans using IIumina sequencing. The Z. simulans chloroplast has a total length of 158,461 bp; it consists of a large single copy (LSC) region of 85,568 bp, a small single copy region (SSC) length of 17,603 bp, and an inverted region (IR) of 27,645 bp. The genome encodes 132 annotated genes, including 87 protein-coding genes, 37 tRNA, and 8 rRNA. The overall GC content of the Z. simulans chloroplast genome was 38.5%. A phylogenomic analysis revealed that Z. simulans are clustered with Z. bungeanum within the genus Zanthoxylum. [ABSTRACT FROM AUTHOR]

Background: The color of endopleura is a vital factor in determining the economic value and aesthetics appeal of nut. Walnuts (Juglans) are a key source of edible nuts, high in proteins, amino acids, lipids, carbohydrates. Walnut had a variety endopleura color as yellow, red, and purple. However, the regulation of walnut endopleura color remains little known. Results: To understand the process of coloration in endopleura, we performed the integrative analysis of transcriptomes and metabolomes at two developmental stages of walnut endopleura. We obtained total of 4,950 differentially expressed genes (DEGs) and 794 metabolites from walnut endopleura, which are involved in flavonoid and phenolic biosynthesis pathways. The enrichment analysis revealed that the cinnamic acid, coniferyl alcohol, naringenin, and naringenin-7-O-glucoside were important metabolites in the development process of walnut endopleura. Transcriptome and metabolome analyses revealed that the DEGs and differentially regulated metabolites (DRMs) were significantly enriched in flavonoid biosynthesis and phenolic metabolic pathways. Through co-expression analysis, CHS (chalcone synthase), CHI (chalcone isomerase), CCR (cinnamoyl CoA reductase), CAD (cinnamyl alcohol dehydrogenase), COMT (catechol-Omethyl transferase), and 4CL (4-coumaroyl: CoA-ligase) may be the key genes that potentially regulate walnut endopleura color in flavonoid biosynthesis and phenolic metabolic pathways. Conclusions: This study illuminates the metabolic pathways and candidate genes that underlie the endopleura coloration in walnuts, lay the foundation for further study and provides insights into controlling nut's colour. [ABSTRACT FROM AUTHOR]

• Codons are essential for transmitting genetic information, and the phenomenon of codon usage bias (CUB) arises when species or genes show preferences for specific synonymous codons. Cymbidium plants, play a significant role in biodiversity conservation and evolutionary research. China, particularly Guizhou Province, is rich in Cymbidium populations. However, studies on codon characteristics in Cymbidium species are limited. • This study comprehensively analyzes of CUB in the chloroplast genomes of 12 Cymbidium species. The findings highlight the importance of natural selection in shaping CUB preferences and emphasize the significance of codon optimization for efficient gene expression. The results contribute to our understanding of Cymbidium genome evolution and have implications for genetic engineering research, resource identification, and exogenous gene expression in Cymbidium plants. Cymbidium plants play a vital role in biodiversity conservation, evolutionary research, and biological protection. Understanding codon usage bias (CUB) in Cymbidium plants is crucial for unraveling the mechanism of species evolution and gene expression. In this study, we systematically analyzed the CUB and identified sources of variance in chloroplast genomes of 12 Cymbidium species to explore the main factors influencing CUB. Using CodonW 1.4.2 software and CUSP program, we screened 52 coding DNA sequences (CDS) within the complete chloroplast genome sequences of the twelve Cymbidium species. Subsequently, neutral, ENC-plot, and PR2-plot mapping analyses were performed to explore the relationships between code usage and genetic elements. The results revealed a consistent bias for guanine-cytosine (GC) bases at the first and second positions (GC1 > GC2 > GC3) of chloroplast genome codons in all 12 Cymbidium species. Moreover, the third base of codons exhibited a predilection for adenine/thymine (A/T) or uracil (U). The effective number of codons (ENC) ranged from 48.6 % to 49.49 %, with an average of 49.07, indicating a weak CUB. Additionally, codon adaptation index (CAI) ranged from 0.167 to 0.171, further supporting the weak CUB. The mapping analyses consistently highlighted natural selection as the primary factor influencing CUB in the 12 orchid chloroplast genomes while acknowledging the impact of other factors, such as mutations. Through optical codon analysis, we identified the top ten preferred codons (UUA, AUU, UCU, CCU, ACU, GCU, AAA, CGA, AGU, and GGU), all of which ended with A or U. These findings provide valuable insights for future studies involving codon modification of foreign genes and the development of high-expression transgenic techniques in Cymbidium plants. [ABSTRACT FROM AUTHOR]

Background: Juglans sigillata L. (walnut) has a high economic value for nuts and wood and has been widely grown and eaten around the world. Light plays an important role in regulating the development of the walnut embryo and promoting nucleolus enlargement, which is one of the factors affecting the yield and quality of walnut. However, little is known about the effect of light on the growth and quality of walnuts. Studies have shown that far red prolonged hypocotyl 3 (FHY3) and far red damaged response (FAR1) play important roles in plant growth, light response, and resistance. Therefore, FHY3/FAR1 genes were identified in walnuts on a genome-wide basis during their growth and development to reveal the potential regulation mechanisms involved in walnut kernel growth and development. Results: In the present study, a total of 61 FHY3/FAR1 gene family members in walnuts have been identified, ranging in length from 117 aa to 895 aa. These gene family members have FHY3 or FAR1 conserved domains, which are unevenly distributed on the 15 chromosomes (Chr) of the walnut (except for the Chr16). All 61 FHY3/FAR1 genes were divided into five subclasses (I, II, III, IV, and V) by phylogenetic tree analysis. The results indicated that FHY3/FAR1 genes in the same subclasses with similar structures might be involved in regulating the growth and development of walnut. The gene expression profiles were analyzed in different walnut kernel varieties (Q, T, and F). The result showed that some FHY3/FAR1 genes might be involved in the regulation of walnut kernel ripening and seed coat color formation. Seven genes (OF07056-RA, OF09665-RA, OF24282-RA, OF26012-RA, OF28029-RA, OF28030-RA, and OF08124-RA) were predicted to be associated with flavonoid biosynthetic gene regulation cis-acting elements in promoter sequences. RT-PCR was used to verify the expression levels of candidate genes during the development and color change of walnut kernels. In addition, light responsiveness and MeJA responsiveness are important promoter regulatory elements in the FHY3/FAR1 gene family, which are potentially involved in the light response, growth, and development of walnut plants. Conclusion: The results of this study provide a valuable reference for supplementing the genomic sequencing results of walnut, and pave the way for further research on the FHY3/FAR1 gene function of walnut. [ABSTRACT FROM AUTHOR]

Background: Understanding the underlying genetic mechanisms that drive phenotypic variations is essential for enhancing the efficacy of crop improvement. Persian walnut (Juglans regia L.), which is grown extensively worldwide, is an important economic tree fruit due to its horticultural, medicinal, and material value. The quality of the walnut fruit is related to the selection of traits such as thinner shells, larger filling rates, and better taste, which is very important for breeding in China. The complex quantitative fruit-related traits are influenced by a variety of physiological and environmental factors, which can vary widely between walnut genotypes. Results: For this study, a set of 101 Persian walnut accessions were re-sequenced, which generated a total of 906.2 Gb of Illumina sequence data with an average read depth of 13.8× for each accession. We performed the genome-wide association study (GWAS) using 10.9 Mb of high-quality single-nucleotide polymorphisms (SNPs) and 10 agronomic traits to explore the underlying genetic basis of the walnut fruit. Several candidate genes are proposed to be involved in walnut characteristics, including JrPXC1, JrWAKL8, JrGAMYB, and JrFRK1. Specifically, the JrPXC1 gene was confirmed to participate in the regulation of secondary wall cellulose thickening in the walnut shell. Conclusion: In addition to providing considerable available genetic resources for walnut trees, this study revealed the underlying genetic basis involved in important walnut agronomic traits, particularly shell thickness, as well as providing clues for the improvement of genetic breeding and domestication in other perennial economic crops. [ABSTRACT FROM AUTHOR]

This study investigates the time-varying interaction between terrorist attacks and oil prices using a bootstrap full-sample causality test and sub-sample rolling window estimations. The results show that terrorist incidents (defined by the occurrence of an attack) and the associated brutality (measured by the number of casualties produced by the attack) may be important factors in explaining changes in oil prices, but their effects differ. Terrorist incidents have both positive and negative time-varying effects on oil prices, but terrorist brutality has only negative effects, and its impact is far less than for terrorist incidents. In contrast, there is weak evidence that terrorist attacks respond in a significant manner to oil prices. Terrorist attacks depend on the long-term influences of various complex factors and the importance of short-term changes in oil prices is negligible. Our research may be helpful to market participants in analyzing and predicting the results of terrorism on oil prices, which has great significance for investment decision-making and risk-avoidance strategies in the oil markets. • This study explores the time-varying interaction between terrorist attacks and oil prices. • Terrorist incidents have both positive and negative time-varying effects on oil prices. • There is weak evidence that terrorist attacks respond in a significant manner to oil prices. • It helps improve the risk response abilities to cope with oil emergencies. [ABSTRACT FROM AUTHOR]

The Yolov4 detection algorithm does not sufficiently extract local semantic and location information. This study aims to solve this problem by proposing a Yolov4-based multiscale feature fusion detection system for high-speed train wheel tread defects. First, multiscale feature maps are obtained from a feature extraction backbone network. The proposed multiscale feature fusion network then fuses the underlying features of the original three scales. These fused features contain more defect semantic information and location details. Based on the fused features, a path aggregation network is used to fuse feature maps at different resolutions, with an improved loss function that speeds up the convergence of the network. Experimental results show that the proposed method is effective at detecting defects in the wheel treads of high-speed trains. [ABSTRACT FROM AUTHOR]

Background: Astrocytes are the most abundant glial cells in a brain that mediate inflammatory responses and provide trophic support for neurons. We have previously disclosed that paroxetine, a common selective serotonin reuptake inhibitor, ameliorates LPS-induced microglia activation. However, it remains elusive for the role of paroxetine in astrocytic responses.Methods: Isolated primary astrocytes were pretreated with paroxetine and stimulated with different stimuli, lipopolysaccharide (LPS) or microglia conditioned medium pre-activated with LPS (M/Lps). Inflammatory and neurotrophic responses, underlying mechanisms and the impact on neuronal survival were assessed.Results: Paroxetine had no impact on LPS-stimulated iNOS, TNF-α, and IL-1β expression, but inhibited M/Lps-induced TNF-α and IL-1β expression in primary astrocytes. Paroxetine suppressed M/Lps- but not LPS-induced activation of NF-κB and had no impact on the activation of MAPKs and STAT3. Incubation with the resulted astrocyte conditioned media caused no change in the viability of SH-SY5Y cells. BDNF and MANF mRNA expressions were upregulated by M/Lps and paroxetine, respectively. However, M/Lps- or LPS-induced extracellular releases of NO, TNF-α, and/or BDNF in astrocytes were in minor amount compared to those by microglia.Conclusions: Paroxetine ameliorates the reactive microglia-mediated inflammatory responses in astrocytes partially via inhibition of the NF-κB pathway but has no impact on LPS-stimulated astrocyte activation. While the effects of paroxetine on secondary astrocytic responses are not robust compared to its effect on the innate immune responses of microglia, the results together may implicate a therapeutic potential of paroxetine against neuroinflammation-associated neurological disorders such as Parkinson's disease. [ABSTRACT FROM AUTHOR]