Search Results (60)

Peptaibols are linear fungal peptides featuring α,α-dialkylated amino acids (e.g., α-aminoisobutyric acid (Aib), isovaline (Iva)) and characteristic C-terminal alcohol groups. Despite their promising antibacterial and antiplasmodial activities, detailed biosynthetic studies remain limited. A genome-guided study of the fungus Trichodema sp. SK1-7, isolated from decaying wood, revealed the production of previously described trichorozin IV (1), along with novel SF4-type peptaibol 2 (trichorozin V). The structures of these compounds were elucidated through MS analysis, NMR study and advanced Marfey’s method. The genome of Trichoderma sp. SK1-7 harbors two PKS-NRPS hybrid gene clusters containing 14 and 18 adenylation domains. Analysis of the modular architecture suggested that trichorozins are synthesized by a 14-module protein via a module skipping mechanism. Genome mining revealed several types of short peptaibol synthase architectures (10–14 adenylation domains) across various Trichoderma species, accompanied by similar long peptaibol synthases. Furthermore, putative Aib/Iva biosynthesis machinery in Trichoderma was identified, showing specific architectures potentially involved in regulating peptaibol biosynthesis. Feeding experiments demonstrated that peptaibol production depends on the ratio of Iva/Aib. The isolated compounds exhibited moderate antibacterial and cytotoxic activities along with a synergistic effect when combined with membrane-targeting antibiotics. Our findings suggest that genome-guided approaches hold promise for further development of peptabiotics with a wide range of applications, including antibiotic adjuvants. Full article

With the rapid development of metaverse technology in the marketing field, it has become increasingly important to understand consumer purchase intentions for AI Brand Endorsers (AIBEs) within this digital environment. Based on cognitive–affective–behavioral (CAB) theory, this study constructs a new theoretical framework to explore the key factors influencing consumer purchase intentions for AIBE-recommended products in the context of the metaverse. We conducted an online survey with 302 Generation MZ consumers who have purchasing experience, employing Partial Least Squares Structural Equation Modeling (PLS-SEM) for in-depth data analysis and model evaluation. Additionally, we performed Multi-Group Analysis (MGA) to reveal differences among various occupations and generations. The findings indicate that attractiveness (ATT), anthropomorphism (ANT), and interactivity (INT) significantly influence hedonic motivation (HM) and social presence (SP). Furthermore, authenticity (AUT) positively affects both SP and trust in AIBEs (TAI). Consumer purchase intention (PI) is significantly impacted by SP but is not directly influenced by HM and TAI. Notably, technology readiness (optimism and innovativeness) positively and significantly influences consumer PI but does not alter the potential moderating effects of HM, SP, and TAI. This study not only broadens and deepens the application of CAB theory but also elucidates the potential development of AIBEs in future metaverse research, providing practical implications and guidance for marketers to enhance consumer purchase intentions and boost product sales. Full article

Aluminum ion batteries (AIBs) exhibit a promising development prospect due to their advantages such as high theoretical specific capacity, high safety, low cost, and sufficient raw material sources. In this work, nanosheet tin disulfide (SnS₂) was successfully prepared using the hydrothermal method and then used as a cathode material for AIBs. The synthesized nano-flake SnS₂ has a large size and thin thickness, with a size of about 900 nm and a thickness of about 150 nm. This electrode material effectively enhances the contact interface with the electrolyte and shortens the depth and travel distance of ion deintercalation. As an electrode, the battery obtained a residual discharge specific capacity of about 55 mAh g⁻¹ and a coulombic efficiency of about 83% after 600 cycles. Furthermore, the first-principles calculation results show that the energy storage mechanism is the deintercalation behavior of Al³⁺. Based on model analysis and calculation results, it can be seen that compared with the position between two sulfur atoms, Al³⁺ is more inclined to be deintercalated directly above the sulfur atom. This study provides fundamental data for the large-scale preparation of AIBs using SnS₂ as an electrode material and the application research of AIBs. Full article

A systematic structure–activity and computational modeling analysis of a series of glucagon-like peptide-1 receptor (GLP-1R) agonists based upon an ultra-short GLP-1 peptide, H-His-Aib-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Bip-Bip-NH2, was conducted. This highly potent 11-mer peptide led to a deeper understanding of the α-helical bias of strategic α-methylation within the linear parent template as well as optimization of GLP-1R agonist potency by 1000-fold. These data were correlated with previously reported co-structures of both full-length GLP-1 analogs and progenitor N-terminal GLP-1 fragment analogs related to such ultra-short GLP-1R agonist peptides. Furthermore, the development of a quantitative structure–activity relationship (QSAR) model to analyze these findings is described in this study. Full article

Currently, exploring high-capacity, stable cathode materials remains a major challenge for rechargeable Aluminum-ion batteries (AIBs). As an intercalator for rechargeable AIBs, Al³⁺ produces three times the capacity of AlCl₄⁻ when the same number of anions is inserted. However, the cathode material capable of producing Al³⁺ intercalation is not a graphite material with AlCl₄⁻ intercalation but a transition metal sulfide material with polar bonding. In this paper, the insertion mechanism of Al³⁺ in 3R-MoS₂ is investigated using first-principles calculations. It is found that Al³⁺ tends to insert into different interlayer positions at the same time rather than occupying one layer before inserting into another, which is different from the insertion mechanism of AlCl₄⁻ in graphite. Ab initio, molecular dynamics calculations revealed that Al³⁺ was able to stabilize the insertion of 3R-MoS₂. Diffusion barriers indicate that Al³⁺ preferentially migrates to nearby stabilization sites in diffusion pathway studies. According to the calculation, the theoretical maximum specific capacity of Al³⁺ intercalated 3R-MoS₂ reached 502.30 mAg h⁻¹, and the average voltage of the intercalation was in the range of 0.75–0.96 V. Therefore, 3R-MoS₂ is a very promising cathode material for AIBs. Full article

Advances in synthetic peptide methodologies have enabled the development of macromolecules mimicking protein properties and have found applications in various fields, particularly in immunology. Furthermore, Sequential Oligopeptide Carriers (SOC_n and CPSOC) have been designed as multi-functional core molecules, to which multiple bio-cargos can be anchored, allowing the construction of high molecular weight molecules (>3000 Da) capable of inducing a strong immune response. This study presents the design and synthesis of the Ac-[K-Aib-C(3,9-Acm; 6,12-SSNC_(Acm)QENSDK)]₄-NH₂ peptide conjugate of branched architecture. The peptide epitope S¹²⁸SNCQENSDK¹³⁷ belongs to the V. berus basic phospholipase A₂, a member of the European viper species’ most lethal protein families. The peptide epitope was synthesized according to the SPPS Fmoc/tBu strategy and characterized by HR-ESI-MS and NMR experiments, while the conjugate was purified by RP-HPLC and characterized by HR-ESI-MS. Full article

Chemoselective reactions have played a crucial role in the development of high-molecular-weight (>3000 Da) macromolecules with a branched architecture, particularly as peptides and epitope-based vaccines have emerged as promising tools for drug development. Based on this, in this study, we designed and synthesized the peptide macromolecule CH₃CO-[K-Aib-C(3,9-CH₂NHCOCH₃; 6,12-DFLC(CH₂NHCOCH₃)KKESEK)]₄-NH₂ [Ac-K-Aib-C(3,9-Acm); 6,12-epitope)]₄-NH₂] using chemoselective thioether bond formation between the peptide carrier CPSOC (3,9 Acm) and the IAc-DFLC_(Acm)KKESEK-NH₂ peptide epitope. The conjugate was purified via RP-HPLC and characterized via HR-ESI-MS. The epitope D¹²⁸FLCKKESEK¹³⁷ derives from the lethal toxin, ammodytoxin A, from the V. ammodytes snake species, and it was synthesized using the SPPS Fmoc/tBu methodology and characterized via HR-ESI-MS and NMR techniques. Full article

In this paper, we study the improved block splitting (IBS) iteration method and its accelerated variant, the accelerated improved block splitting (AIBS) iteration method, for solving linear systems of equations stemming from the discretization of the complex Helmholtz equation. We conduct a comprehensive convergence analysis and derive optimal iteration parameters aimed at minimizing the spectral radius of the iteration matrix. Through numerical experiments, we validate the efficiency of both iteration methods. Full article

Aqueous aluminum-ion batteries (AIBs) have great potential as devices for future large-scale energy storage systems due to the cost efficiency, environmentally friendly nature, and impressive theoretical energy density of Al. However, currently, available materials used as anodes for aqueous AIBs are scarce. In this study, a novel sol-gel method was used to synthesize nitrogen-doped titanium dioxide (N-TiO₂) as a potential anode material for AIBs in water. The annealed N-TiO₂ showed a high discharge capacity of 43.2 mAh g⁻¹ at a current density of 3 A g⁻¹. Analysis of the electrode kinetics revealed that the N-TiO₂ anodes exhibited rapid diffusion of aluminum ions, low resistance to charge transfer, and high electronic conductivity, enabling good rate performance. The successful implementation of a nitrogen-doping strategy provides a promising approach to enhance the electrochemical characteristics of electrode materials for aqueous AIBs. Full article

Aluminum-ion batteries (AIBs) have become a research hotspot in the field of energy storage due to their high energy density, safety, environmental friendliness, and low cost. However, the actual capacity of AIBs is much lower than the theoretical specific capacity, and their cycling stability is poor. The exploration of energy storage mechanisms may help in the design of stable electrode materials, thereby contributing to improving performance. In this work, molybdenum disulfide (MoS₂) was selected as the host material for AIBs, and carbon nanofibers (CNFs) were used as the substrate to prepare a molybdenum disulfide/carbon nanofibers (MoS₂/CNFs) electrode, exhibiting a residual reversible capacity of 53 mAh g⁻¹ at 100 mA g⁻¹ after 260 cycles. The energy storage mechanism was understood through a combination of electrochemical characterization and first-principles calculations. The purpose of this study is to investigate the diffusion behavior of ions in different channels in the host material and its potential energy storage mechanism. The computational analysis and experimental results indicate that the electrochemical behavior of the battery is determined by the ion transport mechanism between MoS₂ layers. The insertion of ions leads to lattice distortion in the host material, significantly impacting its initial stability. CNFs, serving as a support material, not only reduce the agglomeration of MoS₂ grown on its surface, but also effectively alleviate the volume expansion caused by the host material during charging and discharging cycles. Full article

In the face of external disturbances affecting the trajectory tracking of quadrotors, a control scheme targeted at accurate position and attitude trajectory tracking was designed. Initially, a quadrotor dynamic model, essential for control design, was derived. Adaptive integral backstepping control (AIBS) was then employed within the position loop, enabling the upper boundaries of disturbances to be estimated through adaptive estimation. Subsequently, a new adaptive backstepping fast nonsingular integral terminal sliding mode control (ABFNITSM) was proposed to enable adherence to the desired Euler angles. Rapid convergence and accurate tracking were facilitated by the incorporation of the nonsingular terminal sliding mode and an integral component. The dead zone technique was deployed to curtail estimation errors, while a saturation function was used to eradicate the phenomenon of chattering. Finally, to validate the proposed control scheme, simulation experiments were conducted in the Simulink environment, and the results were contrasted with those obtained from traditional integral terminal sliding mode control (ITSM) and integral backstepping control (IBS), providing evidence of the effectiveness of the proposed method. Full article

Ovule abortion, which is the main cause of empty burs in the Chinese chestnut, affects the formation of embryos and further reduces yield; therefore, it is important to study the mechanism of ovule abortion. In this study, we analyzed the transcriptomic and metabolomic data of ovules at critical developmental stages to explore the key regulatory networks affecting ovule development. The metabolites were enriched mainly in pathways involved in phytohormone signaling, energy metabolism, and amino acid synthesis in the endoplasmic reticulum. Analysis of the differentially expressed genes (DEGs) revealed that the HSP genes were significantly down-regulated during fertilization, indicating that this process is extremely sensitive to temperature. The hormone and sucrose contents of ovules before and after fertilization and of fertile and abortive ovules at different developmental stages showed significant differences, and it is hypothesized that that abnormal temperature may disrupt hormone synthesis, affecting the synthesis and catabolism of sucrose and ultimately resulting in the abortive development of Chinese chestnut ovules. At the pollination and fertilization stage of chestnuts, spraying with ethylene, ACC, and AIB significantly increased the number of developing fruit in each prickly pod compared to CK (water) treatment. These results indicated that both ethylene and ACC increased the rate of ovule development. This study provides an important theoretical molecular basis for the subsequent regulation of ovule development and nut yield in the Chinese chestnut. Full article

The fruits of the nopal (Opuntia spp.), cactus pears, are considered functional foods due to their content of nutritive and bioactive substances. Its pulp is generated by numerous seeds that limit their consumption due to their size and hardness and detract from their quality. Other undesirable fruit characteristics are its inedible peel and its short shelf life. In the case of the cactus pear cactus (Opuntia spp.), no cultivar has been reported that produces quality parthenocarpic fruits, nor have they been obtained by artificially inducing parthenocarpy. The objectives of this research were to evaluate the response of 11 genotypes to the induction of parthenocarpy, to characterize the fruits of the genotypes with the best response, and to determine their postharvest life. To induce parthenocarpy, floral buds were used in the pre-anthesis stage, from which the style-stigma, stamens, and tepals were removed, generating a cavity in which a solution of growth regulators was applied (250 mg L⁻¹ AG₃ + 75 mg L ⁻¹ BA + 15 mg L⁻¹ of AIB). A similar number of buds was used as a control, without treatment, and in free pollination. Only two genotypes, MX CP-30 Red and MX CP-40 Yellow, produced parthenocarpic fruits since their empty integuments produced pulp, remaining small, empty, and soft. Their peel was sweet (10–14 °Brix) and edible, and they had a longer shelf life than the corresponding fruits with seeds. Full article

In this work, we developed two new polyfunctional hybrid systems in which the presence of Fc redox “antennas” on peptide scaffolds allows for a modulation of their electronic properties. Specifically, we synthesized two helical hexapeptides containing four Aib (α-amionoisobutyric acid) and two _L-Dap (2,3-diamino propionic acid) residues. _L-Dap side chains were then functionalized with Fc moieties. The structures of the two 3₁₀ helical peptides, namely Z-Aib-_L-Dap(Fc)-Aib-Aib-_L-Dap(Fc)-Aib-NH-iPr and Z-Aib-_L-Dap(Fc)-Aib-_L-Dap(Fc)-Aib-Aib-NH-iPr, were investigated by X-ray diffraction, 2D-NMR, CD and IR spectroscopies. Due to the helical conformation, in Z-Aib-_L-Dap(Fc)-Aib-Aib-_L-Dap(Fc)-Aib-NH-iPr, the Fc groups are located on the same face of the helix, but in Z-Aib-_L-Dap(Fc)-Aib-_L-Dap(Fc)-Aib-Aib-NH-iPr, they are located on opposite faces. Surprisingly, two bands were found through DPV for Z-Aib-_L-Dap(Fc)-Aib-_L-Dap(Fc)-Aib-Aib-NH-iPr, indicating an electrostatic interaction between the Fc groups despite their longer reciprocal distance with respect to that in Z-Aib-_L-Dap(Fc)-Aib-Aib-_L-Dap(Fc)-Aib-NH-iPr. CD experiments at different concentrations evidenced aggregation for Z-Aib-_L-Dap(Fc)-Aib-_L-Dap(Fc)-Aib-Aib-NH-iPr, even at high dilutions, thus suggesting that the Fc-Fc electrostatic interaction could be of an intermolecular nature. Full article

In chloroform solution, the reaction of bis(tert-butylamino)dimethylsilane ((tBuNH)₂SiMe₂) and an α-amino acid (α-amino isobutyric acid, H₂Aib; D-phenylglycine, H₂Phg; L-valine, H₂Val) in the presence of N-methylimidazole (NMI) gave rise to the formation of the pentacoordinate silicon complexes (Aib)SiMe₂-NMI, (Phg)SiMe₂-NMI and (Val)SiMe₂-NMI, respectively. Therein, the amino acid building block was a di-anionic bidentate chelator at the silicon atom. In solution, the complexes were involved in rapid coordination–dissociation equilibria between the pentacoordinate Si complex (e.g., (Aib)SiMe₂-NMI) and its constituents NMI and a five-membered silaheterocycle (e.g., (Aib)SiMe₂), as shown by ²⁹Si NMR spectroscopy. The energetics of the Lewis acid-base adduct formation and the competing solvation of the NMI molecule by chloroform were assessed with the aid of computational methods. In CDCl₃ solution, deuteration of the silaheterocycle NH group proceeded rapidly, with more than 50% conversion within two days. Upon cooling to −44 °C, the chloroform solvates of the adducts (Aib)SiMe₂-NMI and (Phg)SiMe₂-NMI crystallized from their parent solutions and allowed for their single-crystal X-ray diffraction analyses. In both cases, the Si atom was situated in a distorted trigonal bipyramidal coordination sphere with equatorial Si–C bonds and an equatorial Si–N bond (the one of the silaheterocycle). The axial positions were occupied by a carboxylate O atom of the silaheterocycle and the NMI ligand’s donor-N-atom. Full article