RESUMO
The Stone-Wales defect is a well-known and significant defective structure in carbon materials, impacting their mechanical, chemical, and electronic properties. Recently, a novel metal-carbon nanomaterial named Volleyballene was discovered, characterized by a C-C bond bridging two carbon pentagons. Using first-principles calculations, a stable Stone-Wales-defective counterpart of Volleyballene, exhibiting Th symmetry, has been proposed by rotating the C-C bond by 90°. Although its binding energy per atom is slightly higher than that of Volleyballene (ΔEb = 0.009 eV/atom), implying marginally lower structural stability, it can maintain its bond structure until the effective temperature reaches about 1500 K, indicating greater thermodynamic stability. Additionally, its highest vibration frequency is 1346.2 cm-1, indicating a strong chemical bond strength. A theoretical analysis of the Sc20C60 + Sc20C60 binary systems highlights that the stable building block may be applied in potential nanoassemblies.
RESUMO
In this communication, we investigate the lattice dynamics of twisted graphene nanoribbons using the density-functional tight-binding method based on screw symmetry. The results show that the decrease in phonon group velocity induced by twisting reduces the lattice thermal conductivity. Our findings provide inspiration for the design of graphene-based phononic devices tailored by inhomogeneous strain.
RESUMO
Crop resistance plays a role in preventing aphid damage, benefiting food production industries, but its effects are limited due to aphid adaptation and phenotypic plasticity. Therefore, furthering understanding of aphid-crop interactions will improve our ability to protect crops from aphids. To determine how aphids adapt to resistant varieties of wheat, Triticum aestivum L. over time, we performed a laboratory experiment to assess the multi-generational effects of three wheat varieties, Batis, Ww2730, and Xiaoyan22, with different resistance levels on the fitness of Sitobion avenae (Fab.) (Hemiptera: Aphididae). The results showed that Ww2730 and Xiaoyan22 were more resistant than Batis to S. avenae, regardless of whether the aphids were newly introduced or had been acclimated before being introduced to the three wheat varieties. However, the effect of resistance on aphid life-history traits was time dependent. Aphid weigh gain increased and they development faster of the acclimated generation compared to the newly introduced generation on all three varieties. And the fecundity on the three varieties and net reproduction rates on Batis and Xiaoyan22 significantly decreased. Aphid fitness in terms of individual life-history parameters improved, whereas aphid fitness in terms of reproductive decreased, and a convergence effect, the difference gaps and standard errors of all life-history traits among the three acclimated populations had narrowed and were less than those in the three first-generation populations, was observed during the 3-mo experimental period. We suggested that S. avenae could rapidly respond to wheat resistance through life-history plasticity.
Assuntos
Afídeos , Controle de Insetos , Triticum , Animais , Afídeos/crescimento & desenvolvimento , Afídeos/fisiologia , Produtos Agrícolas , Fertilidade , Características de História de Vida , Defesa das Plantas contra Herbivoria , Folhas de Planta , ReproduçãoRESUMO
A chiral molecule with octahedral symmetry, Re6C32, has been identified using first-principles calculations. It is a hollow cage with the shape of Catalan pentagonal icositetrahedron. The calculated vibrational frequencies are in the range of 83.0-1341.2 cm-1, which indicate the stability of the Re6C32 molecule. Molecular dynamics simulations show that the topological structure of the Re6C32 molecule is well maintained up to 1500 K. The electronic structural analysis shows that there are significant p-d orbital hybridizations near the Fermi level. Moreover, the Re6C32 molecule is magnetic with spin magnetic moment of 12 µB. This magnetic carbon-based hollow Re6C32 cage may become a candidate for single-molecule devices.
RESUMO
Fusarium graminearum is a plant pathogen that can cause the devastating cereal grain disease fusarium head blight in temperate regions of the world. Previous studies have shown that F. graminearum can synthetize indole-3-acetic acid (auxin) using l-tryptophan (L-TRP)-dependent pathways. In the present study, we have taken a broader approach to examine the metabolism of L-TRP in F. graminearum liquid culture. Our results showed that F. graminearum was able to transiently produce the indole tryptophol when supplied with L-TRP. Comparative gene expression profiling between L-TRP-treated and control cultures showed that L-TRP treatment induced the upregulation of a series of genes with predicted function in the metabolism of L-TRP via anthranilic acid and catechol towards the tricarboxylic acid cycle. It is proposed that this metabolic activity provides extra energy for 15-acetyldeoxynivalenol production, as observed in our experiments. This is the first report of the use of L-TRP to increase energy resources in a Fusarium species.
Assuntos
Fusarium/metabolismo , Redes e Vias Metabólicas , Triptofano/metabolismo , Grão Comestível/metabolismo , Perfilação da Expressão Gênica , Ácidos Indolacéticos/metabolismo , Indóis , Análise em Microsséries , Tricotecenos , Triticum/genéticaRESUMO
A stable hollow copper silicide cage with Ih symmetry, Cu20Si12, constituted of a copper dodecahedron and a silicon icosahedron, was investigated using density functional theory. Molecular dynamics simulations show that Cu20Si12 retains its geometric topology up to an effective temperature of about 962 K. The molecule has a HOMO-LUMO gap of 1.099 eV, indicating its relatively high chemical stability. These frontier molecular orbitals show clear characteristics of hybridization between Si 3p and Cu 3d electrons. This proposed structure helps to extend the range of high-symmetry molecular polyhedral species. The hollow space within Cu20Si12 can be used to accommodate other atoms or molecules and emphasizes the benefit of studying endohedral fullerenes.
RESUMO
Insects show a variety of responses to electric fields and most of them are associated with immediate effects. To investigate the long-term effects of static electric field on the wheat aphid Sitbion avenae, the insert was exposed to 4 min of a static electric field at intensities of 0, 2, 4, or 6 kV/cm. Development effects over 30 consecutive generations of the insect were studied. The results showed that the electric field could exert adverse effects on the developmental duration and total longevity of S. avenae nymphs regardless of exposure intensities or generations. The effects appeared to be more intense and fluctuated at higher electric field intensities and more insect generations. The most favorable exposure for development was 6 kV/cm for 4 min while the most detrimental electric fields were 2 kV/cm for 4 min and 4 kV/cm for 4 min. Among the treatments, the first instar duration was significantly prolonged while the adult longevities were significantly shortened in the sixth generation. The intrinsic rate of increase and net reproductive rate in the sixth generation were also the lowest among the 30 consecutive generations studied. Based on the results, the adverse effects of electric fields on insects may be used in the bio-control of pest insects in terms of pest management.
Assuntos
Afídeos/crescimento & desenvolvimento , Eletricidade , Controle de Insetos , Triticum , Análise de Variância , Animais , Afídeos/fisiologia , Longevidade , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Reprodução , Eletricidade Estática , Fatores de TempoRESUMO
Similar to carbon-based graphene, fullerenes and carbon nanotubes, boron atoms can form sheets, fullerenes, and nanotubes. Here we investigate several of these novel boron structures all based on the boron double ring within the framework of density functional theory. The boron sheet is found to be metallic and flat in its ground state. The spherical boron cage containing 180 atoms is also stable and has I symmetry. Stable nanotubes are obtained by rolling up the boron sheet, and all are metallic. The hydrogen storage capacity of boron nanostructures is also explored, and it is found that Li-decorated boron sheets and nanotubes are potential candidates for hydrogen storage. For Li-decorated boron sheets, each Li atom can adsorb a maximum of 4 H2 molecules with g(d) =7.892 wt %. The hydrogen gravimetric density increases to g(d) =12.309 wt % for the Li-decorated (0,6) boron nanotube.
RESUMO
As a selective stress, heavy metals play an important role in inducing the adaptive adjustments of insects to changing environments. Carboxylesterase (CarE) is one kind of biomarker that could help us to explore the adaptation mechanism of aphids to heavy metal stress. In this study, CarE activity and gene expression level were investigated in English grain aphids, Sitobion avenae (F.) (Hemiptera: Aphididae), exposed to Zn2+ at concentrations of 0, 400, and 1600 mg/kg for 5, 15, 25, and 30 generations. The results showed that the CarE activity was significantly different between different Zn2+ concentrations and different generations. The CarE activity significantly decreased with increasing generations. In the higher generations, the CarE activity was strongly inhibited by the 1600 mg/kg of Zn2+. Realtime quantitative PCR revealed that the CarE gene expression pattern in S. avenae was up-regulated under the condition of 400 mg/kg and 1600 mg/kg of Zn2+, but a significant difference was not found after long-term exposure to high concentrations of Zn2+. It was concluded that CarE could be the sensitive biomarker for S. avenae response to the presence of Zn2+. In order to adapt to heavy metal Zn2+ stress, S. avenae had particular patterns of gene expression under long-term stress.
Assuntos
Afídeos/efeitos dos fármacos , Afídeos/metabolismo , Carboxilesterase/metabolismo , Proteínas de Insetos/metabolismo , Zinco/farmacologia , Animais , Carboxilesterase/genética , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Insetos/genética , Folhas de Planta/química , Folhas de Planta/metabolismo , Triticum/química , Triticum/metabolismo , Zinco/químicaRESUMO
The Kelvin problem, how to partition three-dimensional space into cells of equal volume with minimal area, is a fascinating one. Aggregations of bubbles are naturally physical illustrations of the Kelvin problem. And the superconductor Na8Si46 as an inspiration leads to an amazing discovery of the Weaire-Phelan (WP) structure of foam - the optimal solution to the Kelvin problem to date. Here based on the structural similarity between sp(3)-bonded silicon allotropes and the solutions to the Kelvin problem, a series of new sp(3)-hybridization silicon allotropes, named "Kelvin Silicons", are presented. Furthermore, the structural stability and electronic properties of these new silicon allotropes are investigated using density-functional theory (DFT) calculations. The results show that Kelvin Silicons are structurally stable semiconductors with indirect bandgaps in the range of 0.17-1.40 eV, and their bulk moduli are about 75.9-88.5% that of the diamond phase. The simulated X-ray diffraction spectra of the new silicon crystalline structures would provide more information for possible experimental observations and synthesis.
RESUMO
As children's toys, soap bubbles also underpin many important scientific questions. What is the most efficient structure for foam? - the "Kelvin problem," has been one of the most intriguing science and widely discussed over the past hundred years. Soap bubbles' frameworks have similar topology with sp(3)-bonded carbon or silicon allotropes, e.g., Weaire-Phelan foam and superconducting clathrate Na8Si46. By looking at the most efficient structure for foams, we construct a series of new carbon allotropes, named "Kelvin carbons." Unexpectedly, all 11 Kelvin carbons are structurally stable wide-bandgap semiconductors, and their densities and their intrinsic hardnesses are both about 81%-87% that of diamond. The seventh state of Kelvin carbons, K(VII), is a very low energy carbon structure after graphite, diamond, lonsdaleite, and type-II carbon clathrate. Kelvin carbons, which constitute a "bridge" between macro-foams and micro-carbons, together with recently proposed novel carbon phases can enrich the study of carbon allotropes.
Assuntos
Carbono/química , Teoria QuânticaRESUMO
Winter wheat resistance is an efficient and environmentally friendly means to controlling aphids. By using principal component analysis and correlation analysis, we evaluated the resistance of 10 winter wheat varieties or lines from three countries to the following three aphid species: Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum. The data show that Batis was susceptible to Si. avenae and R. padi, but had adverse effect on the development of Sc. graminum; Astron was advantageous to WG and r(m) of Si. avenae and R. padi, but not to Sc. graminum; Amigo was resistant to Sc. graminum and R. padi, but susceptible to Si. avenae; 98-10-35 was resistant to Si. avenae and R. padi, but not to Sc. graminum; 98-10-30 was adverse to growth and fecundity of Si. avenae, but better for Sc. graminum and R. padi; Xiaoyan22 was susceptible to Sc. graminum, but not to R. padi; Ww2730 were resistant to Si. avenae, but susceptible to Sc. graminum; 186tm was susceptible to R. padi, but caused high mortality for Si. avenae and Sc. graminum. Correlation analysis suggests the wheat varieties or lines that were resistant to Si. avenae were always resistant to R. padi, but susceptible to Sc. graminum. However, the overall similarities in resistance classifications were not because of the same phenotypic characters of the wheat varieties or lines. We conclude that the wheat varieties or lines had specific different resistances to the three aphid species, and the resistant traits (antibiosis) can be defined at two or more hierarchical levels. There was even a stronger "trade-off" for the comparison of Si. avenae versus Sc. graminum and R. padi versus Sc. graminum.
Assuntos
Antibiose , Afídeos/fisiologia , Triticum/fisiologia , Análise de Variância , Animais , Afídeos/genética , Afídeos/crescimento & desenvolvimento , Aptidão Genética , Herbivoria , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Controle Biológico de Vetores , Fenótipo , Análise de Componente Principal , Especificidade da Espécie , Triticum/genéticaRESUMO
The English grain aphid, Sitobion avenae (F.) (Homoptera: Aphididae), is a dominant and destructive pest in wheat, Triticum estivum L. (Poales: Poaceae), production regions in China and other grain-growing areas worldwide. Patterns of gene expression of the S. avenae-resistant synthetic wheat line 98-10-35, the S. avenae-susceptible line1376, and their hybrid population, and the differences in segments between 98-10-35/1376 F3 resistant plants and resistant parents of 98-10-35, as well as those between the F3 resistant and susceptible populations, were examined with differential display reverse transcription PCR. The results showed that five patterns of differential expression were detected between the progeny and its resistant parents: 1) The gene was silenced in one of the parents; 2) Special expression showed in the progeny; 3) Expression was consistent with the resistant parents; 4) Up expression showed in the progeny but not in the parents; 5) Down expression showed in the progeny but not in the parents. Paired t-test results were not significant; however, the probability value (0.9158) indicated that gene expression on the RNA level were consistent with resistant bands found in F3 resistant individuals and resistant parents, as well as the F3 resistant and susceptible populations. For both the F3 of 98-10-35/1376 and the parents, the total number of amplified bands was 202, with an average of 25.3 per primer. The number of differential bands was 116, with an average of 14.5 per primer amplified and a polymorphism ratio of 56.3%. In the present study, differential expression genes in the resistant line 98-10-35 were all up-regulated. Among them, gene expression of resistant groups in the F3 population was in agreement with patterns 2, 3, and 4. However, the susceptible line 1376 did not have this gene expression on the RNA level. This pattern is expected to be used to select and analyze target genes from the same F3 population and the resistant parents. The results suggest that it can be employed as a new method for molecular assisted breeding.
Assuntos
Antibiose , Regulação da Expressão Gênica , Proteínas de Plantas/genética , Triticum/fisiologia , Animais , Afídeos/fisiologia , Cruzamento , China , Cadeia Alimentar , Hibridização Genética , Proteínas de Plantas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Triticum/genéticaRESUMO
Background: Adhesive capsulitis is a progressive, idiopathic disorder that significantly impacts individualsÌ daily lives and increases their medical burden. Pharmacopuncture therapy, which combines acupuncture techniques with herbal medicine, involves injecting herbal extracts into specific acupoints. This study aims to determine the effectiveness and safety of pharmacopuncture therapy in comparison to physiotherapy (PT) for treating adhesive capsulitis. Methods: This research protocol outlines a two-arm, parallel, multi-center, pragmatic randomized controlled trial. Fifty participants will be randomly allocated to either the pharmacopuncture therapy or PT group, and they will receive 12 sessions of their respective therapies over a 6-week period. The primary outcome measure is the numeric rating scale for shoulder pain. Secondary outcomes include the visual analog scale score for shoulder pain, Shoulder Pain and Disability Index, PatientsÌ Global Impression of Change score, Short Form-12 Health Survey Version 2 score, and EuroQol-5 Dimension. Statistical analysis will be conducted based on the intention-to-treat principle. Discussion: This trial may offer high-quality and reliable clinical evidence for evaluating the effectiveness and safety of pharmacopuncture therapy compared to PT in the treatment of adhesive capsulitis. Furthermore, this study will serve as a valuable guideline for practitioners when making clinical decisions and managing adhesive capsulitis.
Assuntos
Terapia por Acupuntura , Acupuntura , Bursite , Humanos , Terapia por Acupuntura/métodos , Bursite/terapia , Estudos Multicêntricos como Assunto , Modalidades de Fisioterapia , Projetos de Pesquisa , Dor de Ombro/terapia , Resultado do Tratamento , Ensaios Clínicos Pragmáticos como AssuntoRESUMO
The light weight, electrical conductivity, environmental friendliness, and high mechanical properties of graphene/PEKK composites make them popular in biomedical, electronic component and aerospace fields. However, the compaction density and carbonization of the specimen influence the microstructure and conductivity of the graphene/PEKK composite prepared by in situ polymerization, so electromagnetic-assisted molding was used to manufacture products to avoid carbonization and enhance the compaction density. The effects of different discharge voltages on the microstructure of the formed graphene/PEKK specimens were compared. Increasing the discharge voltage will lead to a closer distribution of flake graphene in the matrix to improve the compaction density, mechanical performance and conductivity. At the same time, the numerical analysis model was validated by comparison with the compaction density of the experimental results. Based on this research, the stress/strain distribution on the specimen was obtained with increasing discharge voltages.
RESUMO
The effects of cadmium (Cd) on the development, fecundity, and reproduction of the grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae) were estimated by constructing a life table of S. avenae exposed to Cd. The concentrations of Cd in the soil were as follows: 0, 10, 20, 40, 80, and 160 mg/kg. The correlation analysis of the Cd concentration in soil and wheat revealed that the amount in the wheat increased with the increase of Cd concentrations in soil. The results indicated that, the latter part of the reproduction period was significantly affected by Cd, according to the curve of the total survival rate (l(x)). The net reproductive rate (R(0)), innate capacity of increase (r), and finite rate of increase (λ) of S. avenae all decreased under the stress of Cd, and were lowest at a Cd concentration of 20 mg/kg. Cd also negatively affected fecundity and m(x) (the number of offspring produced by an individual female). At 20 mg/kg, the decline of them was most obvious. In conclusion, survival and reproduction of S. avenae were inhibited under the treatment of the heavy metal Cd. Sitobion avenae was more sensitive to Cd at concentration of 20 mg/kg compared to the other concentrations. This concentration can be used to examine the mechanisms behind population genetics and biological mutation of S. avenae when exposed to heavy metal.
Assuntos
Afídeos/efeitos dos fármacos , Cádmio/farmacologia , Poluentes Ambientais/farmacologia , Animais , Afídeos/crescimento & desenvolvimento , Afídeos/fisiologia , Relação Dose-Resposta a Droga , Feminino , Tábuas de Vida , Masculino , Reprodução , TriticumRESUMO
BACKGROUND: This systematic review aimed to assess the effectiveness and safety of acupoint catgut embedding (ACE), which is widely used in simple obese patients. METHODS: Nine electronic databases and 2 trial registries were searched from inception to September 2021 without language limitations. All randomized controlled trials involving ACE therapies for simple obesity were included. Assessment of Cochrane's risk of bias and meta-analysis, as well as GRADE evaluation, were also performed. RESULTS: A total of 73 randomized clinical trials involving 5872 participants were included. The overall risk of bias was high or unclear. ACE showed higher efficacy in total effective rate, body mass index, and body weight than manual acupuncture. In addition, ACE is more beneficial in total effective rate than electroacupuncture (EA). Moreover, combination therapy of ACE with EA is more effective in total body mass index and body weight than EA alone. CONCLUSIONS: Despite some potential improvement, the evidence regarding the effectiveness and efficacy of ACE for simple obesity is inconclusive due to the poor quality of evidence. Further well-designed randomized controlled trials are needed to confirm the effectiveness of ACE for simple obesity.
Assuntos
Terapia por Acupuntura , Obesidade Mórbida , Humanos , Pontos de Acupuntura , Categute , Revisões Sistemáticas como Assunto , Metanálise como Assunto , Terapia por Acupuntura/métodos , Obesidade/terapia , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Crop resistance and biological control are both considered efficient and environmentally friendly methods of sustainable pest control. In this study, we aimed at investigating the direct influence of four wheat lines with varying resistance level on the life-history traits of the greenbug, Schizaphis graminum, and the mediational effect on the functional response of a predatory ladybird, Propylaea japonica, under laboratory conditions. Results showed that the aphid fitness was the lowest for aphids that had been feeding on wheat line '98-10-19' for one year. These aphids had the longest development time, and least adult mass, minimal mean relative growth rate, and lowest reproductive fitness. In contrast, the aphids that fed on wheat line '98-10-30' were the fittest, with the shortest development time and highest levels of reproductive fitness. The predatory activities of the ladybeetle, especially the adult male significantly decreased following the consumption of aphids belonging to the '98-10-19'-acclimated population. However, there were no significant differences in predatory efficiency (net attack frequency) among the four aphid acclimated populations. Our results showed that the wheat line '98-10-19' has a relative higher resistance to S. graminum than the other three wheat lines, which could further decrease the amount of prey available for consumption. However, the ecological effect of the resistance of '98-10-19' to S. graminum posed no negative influence on the biocontrol potential of P. japonica to these aphids, as their predatory efficiency increases at the fourth instar larvae phase.
RESUMO
A stable core-shell volleyball-like structure of B12@Li20Al12 has been proposed using first-principles calculations. This structure with T h symmetry is constructed with a core structure of I h-B12 and a volleyball-like shell of Li20Al12. Frequency analysis and molecular dynamics simulations demonstrate the exceptional stability of B12@Li20Al12. The chemical bonding analysis for B12@Li20Al12 is also conducted to confirm its stability and 46 multi-center two-electron σ bonds are observed, which are widely distributed throughout the core-shell structure. For the hydrogen storage capacity of the B12@Li20Al12, our calculated results indicate that about 58 H2 molecules can be absorbed at most, leading to a gravimetric density of 16.4 wt%. The exceptionally stable core-shell volleyball-like B12@Li20Al12 combined with its high hydrogen storage capacity indicates that it can be one of the outstanding hydrogen storage materials of the future.
RESUMO
Hormone-dependent responses in host plants induced by herbivore infestation have species-specific effects. This study focused on determining the relative expression profiles of the genes associated with hormone-dependent pathways in two near-isogenic wheat lines when attacked by cereal aphids. Infestation with Rhopalosiphum padi Linnaeus (Hemiptera: Aphididae) and/or Sitobion avenae Fabricius (Hemiptera: Aphididae) significantly upregulated the expression of marker genes related to the salicylic acid (SA)- and jasmonic acid (JA)-dependent pathways in the tested lines. In the resistant line 35-E4, previous infestation with R. padi significantly increased the relative expression of plant pathogenesis-related protein 1 at all sampling times but did not have a significant effect on the expression of the phenylalanine ammonia-lyase (PAL) gene. In addition, the expression levels of the lipoxygenase (LOX) and allene oxide synthase (AOS) genes immediately increased after the aphid attack. In susceptible line 35-A20, infestation with either R. padi or S. avenae led to significantly increased expression levels of the AOS and PAL genes. Moreover, sequential aphid infestation induced higher expression of AOS compared with a single-species aphid infestation, whereas the expression of the PAL gene was antagonistically affected by sequential aphid infestation. Overall, these results showed that aphid infestation induced SA- and JA-dependent responses in host plants. However, the expression profiles of these genes in resistant and susceptible host lines were significantly different.