Search Results (59)

Accurate imaging methods are important for understanding electrodeposition phenomena in metal batteries. Among the suitable imaging methods for this task is magnetic resonance imaging (MRI), which is a very powerful radiological diagnostic method. In this study, MR microscopy was used to image electroplating in a lithium symmetric cell, which was used as a model for a lithium-metal battery. Lithium electrodeposition in this cell was studied by sequential 3D ¹H MRI of 1 M LiPF₆ in EC/DMC electrolyte under different charging conditions, which resulted in different dynamics of the amount of electroplated lithium and its structure. The acquired images depicted the electrolyte distribution, so that the images of deposited lithium that did not give a detectable signal corresponded to the negatives of these images. With this indirect MRI, phenomena such as the transition from a mossy to a dendritic structure at Sand’s time, the growth of whiskers, the growth of dendrites with arborescent structure, the formation of dead lithium, and the formation of gas due to electrolyte decomposition were observed. In addition, the effect of charge and discharge cycles on electrodeposition was also studied. It was found that it is difficult to correctly predict the occurrence of these phenomena based on charging conditions alone, as seemingly identical conditions resulted in different results. Full article

High-entropy ceramics (HECs) have garnered considerable interest due to their exceptional mechanical properties and high-temperature stability. Nevertheless, their inherent brittleness significantly restricts industrial applications, posing a challenge to improving toughness without compromising hardness. This study investigates the role of SiC whiskers (SiCw) in simultaneously suppressing grain growth and enhancing the toughness of high-entropy (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C (HEC) composites, while maintaining high hardness during high-pressure high-temperature (HPHT) sintering. HEC-SiCw composites were fabricated via HPHT (P = 5 GPa, T = 2000 °C), with SiCw contents ranging from 0 to 40 mol%. As the SiCw content increased, the growth of HEC grains was inhibited, and the fracture toughness progressively rose to a peak value (K_IC = 9.4 ± 1.2 MPa·m^1/2), representing an increase of approximately 184% compared to that of pure HEC, while Vickers hardness remained stable at 26 GPa. The enhancement in fracture toughness is attributed to the heterogeneous grain distribution and robust grain boundary strength, which facilitated a synergistic combination of transgranular and intergranular fracture mechanisms. These mechanisms induced crack deflection and whisker pull-out, effectively dissipating fracture energy and impeding crack propagation, thereby enhancing toughness. This study presents a novel approach to simultaneously refine grain size and improve toughness in HECs through HPHT processing, providing valuable insights for the development of next-generation ceramic composites. Full article

Soldering with Sn alloys has always been the essential assembly step of microelectronics. The conductive Sn whiskers, which can spontaneously grow from soldering surfaces, mean a considerable reliability risk for microelectronics due to possible short circuit formation between the leads of the components. Since their discovery in 1951, thousands of research studies have been conducted to unravel their growth mechanisms and find effective prevention methods against them. Till 2006, the Sn whisker problem was solved and partially forgotten due to the very effective whisker suppression effect of Pb alloying into the solder materials. The lead-free change gave new impetus to the problem, which was further enhanced by the application of new material systems, growing reliability requirements, and accelerating miniaturization in the 21st century. Our review would like to give an overview of the Sn whisker’s history from the beginning till the latest results, focusing on the suppression solutions by the modification of the solder alloy compositions. Recently, promising results have been reached by alloying Bi and In, which are metals that are the focus of low-temperature soldering, and by composite solders. Full article

Aspartic proteases (APs), hydrolases with aspartic acid residues as catalytic active sites, are closely associated with processes such as plant growth and development and fungal and bacterial pathogenesis. F. graminearum is the dominant pathogenic fungus that causes Fusarium head blight (FHB) in wheat. However, the relationship of APs to the growth, development, and pathogenesis of F. graminearum is not clear. Therefore, we selected the FGSG_09558 gene, whose function annotation is aspartate protease, for further study. In this study, FGSG_09558 was found to contain a conserved structural domain and signal peptide sequence of aspartic acid protease and was therefore named FgAsp. The function of FgAsp in F. graminearum was investigated by constructing the knockout and complementation mutants of this gene. The results showed that with respect to the wild type (PH-1), the knockout mutant showed a significant reduction in mycelial growth, asexual spore production, and sexual spore formation, highlighting the key role of FgAsp in the growth and development of F. graminearum. In addition, the mutants showed a significant reduction in the virulence and accumulation level of deoxynivalenol (DON) content on maize whiskers, wheat germ sheaths, and wheat ears. DON, as a key factor of virulence, plays an important role in the F. graminearum infection of wheat ears, suggesting that FgAsp is involved in the regulation of F. graminearum pathogenicity by affecting the accumulation of the DON toxin. FgAsp had a significant effect on the ability of F. graminearum to utilize various sugars, especially arabinose. In response to the stress, hydrogen peroxide inhibited the growth of the mutant most significantly, indicating the important function of FgAsp in the strain’s response to environmental stress. Finally, FgAsp plays a key role in the regulation of F. graminearum growth and development, pathogenicity, and environmental stress response. Full article

This study investigates the mechanism and effects of incorporating different ZrO₂ nano-particles into SAC0307 solder alloys. ZrO₂ nano-powder and nano-fibers in 0.25–0.5 wt% were added to the SAC0307 alloy to prepare composite solder joints by surface mount technology. The solder joints were shear tested before and after a 4000 h long 85 °C/85% RH corrosive reliability test. The incorporation of ZrO₂ nano-particles enhanced the initial shear force of the solder joint, but they decreased the corrosion resistance in the case of 0.5 wt%. SEM, EDS, and FIB analysis revealed intensive growth of SnO₂ on the solder joint surfaces, leading to the formation of Sn whiskers. Density functional theory (DFT) simulations showed that, despite Sn being able to bond to the surface of ZrO₂, the binding energy was weak, and the whole system was therefore unstable. It was also found that ZrO₂ nano-particles refined the microstructure of the solder joints. Decreased β-Sn grain size and more dispersed intermetallic compounds were observed. The microstructural refinement caused mechanical improvement of the ZrO₂ composite solder joints by dispersion strengthening but could also decrease their corrosion resistance. While ZrO₂ nano-particles improved the solder joint mechanical properties, their use is recommended only in non-corrosive environments, such as microelectronics for space applications. Full article

Pack boriding with CeO₂ was performed on the powder metallurgical (PM) near-α type titanium alloy at a temperature of 1273–1373 K for 5–15 h followed by air cooling. The microstructure analysis showed that the boride layer on the surface of the alloy was mainly composed of a monolithic TiB₂ outer layer, inner whisker TiB and sub-micron sized flake-like TiB layer. The growth kinetics of the TiB₂ and TiB layers obeyed the parabolic diffusion model. The diffusion coefficient of boron in the boride layers obtained in the present study was well within the ranges reported in the literature. The activation energies of boron in the TiB₂ and TiB layers during the pack boriding were estimated to be 166.4 kJ/mol and 122.8 kJ/mol, respectively. Friction tests showed that alloys borided at moderate temperatures and times had lower friction coefficients, which may have been due to the fine grain strengthening effect of TiB whiskers. The alloy borided at 1273 K for 10 h had a minimum friction coefficient of 0.73. Full article

Porous sound absorption ceramic is one of the most promising materials for effectively eliminating noise pollution. However, its high production cost and low mechanical strength limit its practical applications. In this work, low-cost and in situ mullite whisker-reinforced porous sound-absorbing ceramics were prepared using recyclable construction waste and Al₂O₃ powder as the main raw materials, and AlF₃ and CeO₂ as the additives, respectively. The effects of CeO₂ content, AlF₃ content, and sintering temperature on the microstructure and properties of the porous ceramics were systematically investigated. The results showed that a small amount of CeO₂ significantly promoted the growth of elongated mullite crystals in the resultant porous ceramics, decreased the growth temperature of the mullite whiskers, and significantly increased the biaxial flexural strength. When 2 wt.% CeO₂ and 12 wt.% AlF₃ were added to the system, mullite whiskers were successfully obtained at a sintering temperature of 1300 °C for 1 h, which exhibited excellent properties, including an open porosity of 56.4 ± 0.6%, an average pore size of 1.32–2.54 μm, a biaxial flexural strength of 23.7 ± 0.9 MPa, and a sound absorption coefficient of >0.8 at 800–4000 Hz. Full article

The effects of Ti doping on the microstructure and properties of SiC_p/Al composites fabricated by pressureless infiltration were comprehensively investigated using first-principles calculations and experimental analyses. First-principles calculations revealed that the interface wetting and bonding strength in an Al/SiC system could be significantly enhanced by Ti doping. Subsequently, the Ti element was incorporated into SiC preforms in the form of TiO₂ and TiC to verify the influence of Ti doping on the pressureless infiltration performance of SiC_p/Al composites. The experimental results demonstrated that the pressureless infiltration of molten Al into SiC preforms was promoted by adding TiC or TiO₂ due to the improved wettability. However, incorporating TiO₂ leads to the growth of AlN whiskers under a N₂ atmosphere, thereby hindering the complete densification of the composites. On the other hand, TiC doping can improve wettability and interface strength without deleterious reactions. As a consequence, the TiC-doped SiC_p/Al composites exhibited excellent properties, including a high relative density of 99.4%, a bending strength of 287 ± 18 MPa, and a thermal conductivity of 142 W·m⁻¹·K⁻¹. Full article

Based on two-dimensional green phosphorene, we designed two molecular electronic devices with zigzag (Type 1) and whisker-like (Type 2) configurations. By combining density functional theory (DFT) and non-equilibrium Green’s function (NEGF), we investigated the electronic properties of Types 1 and 2. Type 1 exhibits an interesting negative differential resistance (NDR), while the current characteristics of Type 2 show linear growth in the current–voltage curve. We studied the electronic transport properties of Type 1 under uniaxial strain modulation and find that strained devices also exhibit a NDR effect, and the peak-to-valley ratio of device could be controlled by varying the strain intensity. These results show that the transport properties of green phosphorene with different edge configuration are different, and the zigzag edge have adjustable negative differential resistance properties. Full article

French beans are tender, immature, edible pods that are harvested early in the plant’s growth cycle and are usually eaten cooked. The growth habits of French beans were studied for the first time in a Citizen Science experiment, and 19 pod samples were collected for further nutritional analysis. Various macronutrients (e.g., protein, ash, fat, carbohydrates, amino acids) and multi-element profiles were determined. A survey of their growing habits revealed that beans are usually planted once or twice a year in May and June at a length of 5–10 m, with a predominance of dwarf beans cultivation over climbing varieties, and pest resistance and stringless pods are the most important characteristics when deciding on a bean. Homogenised freeze-dried pod samples contained 16.1–23.1% protein, 4.5–8.2% ash, 0.1–1.1% fat, and 62.0–70.6% carbohydrates and had a caloric value of 337–363 kcal/100 g. Of the 17 free amino acids identified, 8 were essential (histidine, threonine, methionine, valine, lysine, isoleucine, leucine, phenylalanine) and 9 were non-essential (cysteine, aspartic acid, serine, glutamic acid, glycine, arginine, alanine, proline, tyrosine); meanwhile, of the 12 elements, 5 were macroelements and 7 were microelements. The predominant free amino acids were aspartic acid, glutamic acid, and serine. In the multiple comparisons (Box and Whisker plot), the parameters caloric value and iron showed the strongest response. A very strong positive significant Pearson correlation (≥0.95) was found for five pairs of variables within the free amino acids. Comparison of the nutrient data obtained in the pods showed near-perfect or high complementarity (85.2–103.4%) with the food composition databases for half of the parameters, suggesting that the home-grown French beans from the Citizen Science experiment are a highly nutritious vegetable. Full article

Spontaneous Sn whisker growth, as a reliability issue in electronic assemblies, has drawn much attention in the past several decades. However, the underlying mechanism is still ambiguous. Herein, the growth of Sn whiskers on pure Sn with different specific surface areas was studied to elucidate the effect of surface energy on Sn whisker growth. Though fabricated and cultivated using the same parameters, it was found that Sn whiskers were obtained on the sample of nano-Sn, which possesses excess surface energy, while no whiskers were observed on the sample of micro-Sn, indicating that surface energy plays a significant role in Sn whisker growth. In addition, the whiskering phenomenon is confirmed to be an abnormal recrystallization process according to the microstructure of the whisker root. Therefore, a Sn whisker growth mechanism companied with an abnormal recrystallization process is proposed, which is driven by the excess surface energy. This work provides a new perspective on understanding the long-standing Sn whiskering problem. Full article

Functional hyperemia—activity-dependent increases in local blood perfusion—underlies the on-demand delivery of blood to regions of enhanced neuronal activity, a process that is crucial for brain health. Importantly, functional hyperemia deficits have been linked to multiple dementia risk factors, including aging, chronic hypertension, and cerebral small vessel disease (cSVD). We previously reported crippled functional hyperemia in a mouse model of genetic cSVD that was likely caused by depletion of phosphatidylinositol 4,5-bisphosphate (PIP₂) in capillary endothelial cells (EC) downstream of impaired epidermal growth factor receptor (EGFR) signaling. Here, using EC-specific EGFR-knockout (KO) mice, we directly examined the role of endothelial EGFR signaling in functional hyperemia, assessed by measuring increases in cerebral blood flow in response to contralateral whisker stimulation using laser Doppler flowmetry. Molecular characterizations showed that EGFR expression was dramatically decreased in freshly isolated capillaries from EC-EGFR-KO mice, as expected. Notably, whisker stimulation-induced functional hyperemia was significantly impaired in these mice, an effect that was rescued by administration of PIP₂, but not by the EGFR ligand, HB-EGF. These data suggest that the deletion of the EGFR specifically in ECs attenuates functional hyperemia, likely via depleting PIP₂ and subsequently incapacitating Kir2.1 channel functionality in capillary ECs. Thus, our study underscores the role of endothelial EGFR signaling in functional hyperemia of the brain. Full article

Many people suffer from hair loss and abnormal skin pigmentation, highlighting the need for simple assays to support drug discovery research. Current assays have various limitations, such as being in vitro only, not sensitive enough, or unquantifiable. We took advantage of the bilateral symmetry and large size of mouse whisker follicles to develop a novel in vivo assay called “whisker follicle microinjection assay”. In this assay, we plucked mouse whiskers and then injected molecules directly into one side of the whisker follicles using microneedles that were a similar size to the whiskers, and we injected solvent on the other side as a control. Once the whiskers grew out again, we quantitatively measured their length and color intensity to evaluate the effects of the molecules on hair growth and coloring. Several chemicals and proteins were used to test this assay. The chemicals minoxidil and ruxolitinib, as well as the protein RSPO1, promoted hair growth. The effect of the clinical drug minoxidil could be detected at a concentration as low as 0.001%. The chemical deoxyarbutin inhibited melanin production. The protein Nbl1 was identified as a novel hair-growth inhibitor. In conclusion, we successfully established a sensitive and quantitative in vivo assay to evaluate the effects of chemicals and proteins on hair growth and coloring and identified a novel regulator by using this assay. This whisker follicle microinjection assay will be useful when investigating protein functions and when developing drugs to treat hair loss and abnormal skin pigmentation. Full article

Genetic transformation is an important strategy for enhancing plant biomass or resistance in response to adverse environments and population growth by imparting desirable genetic characteristics. Research on plant genetic transformation technology can promote the functional analysis of plant genes, the utilization of excellent traits, and precise breeding. Various technologies of genetic transformation have been continuously discovered and developed for convenient manipulation and high efficiency, mainly involving the delivery of exogenous genes and regeneration of transformed plants. Here, currently developed genetic transformation technologies were expounded and compared. Agrobacterium-mediated gene delivery methods are commonly used as direct genetic transformation, as well as external force-mediated ways such as particle bombardment, electroporation, silicon carbide whiskers, and pollen tubes as indirect ones. The regeneration of transformed plants usually involves the de novo organogenesis or somatic embryogenesis pathway of the explants. Ectopic expression of morphogenetic transcription factors (Bbm, Wus2, and GRF-GIF) can significantly improve plant regeneration efficiency and enable the transformation of some hard-to-transform plant genotypes. Meanwhile, some limitations in these gene transfer methods were compared including genotype dependence, low transformation efficiency, and plant tissue damage, and recently developed flexible approaches for plant genotype transformation are discussed regarding how gene delivery and regeneration strategies can be optimized to overcome species and genotype dependence. This review summarizes the principles of various techniques for plant genetic transformation and discusses their application scope and limiting factors, which can provide a reference for plant transgenic breeding. Full article

Species of the genus Pseudoplatystoma, the long-whiskered catfishes, are important in commercial and recreational fisheries in South America, and some species have become key to regional aquaculture. Some species of the genus are under pressure due to overfishing and the negative impacts of dams. Six questions are asked in this review: (i) What species are in the genus, and where are they distributed? (ii) What are the life histories and ecologies of Pseudoplatystoma species? (iii) What are the patterns of somatic growth for these species? (iv) What is known about the biomass, production, and population dynamics of Pseudoplatystoma? (v) What is the geographic distribution of genetic variation within Pseudoplatystoma species? (vi) What are the threats to the conservation of these species? The taxonomy of the genus currently includes eight species, respectively, distributed over the Orinoco, Amazon, Paraná, and São Francisco basins. Pseudoplatystoma catfishes typically exhibit longitudinal migrations for reproduction and lateral migration for feeding, but these patterns may vary among populations. The size of the first maturation of these catfishes varies between 57 cm to 82 cm in total length. Five of the eight species spawn during the rising water season. Pseudoplatystoma species can grow to about 130 cm in total length and 100 Kg in weight and live until 30 years of age, depending upon the species. Biomass production and population dynamics of these catfishes have not yet been fully described. Their life-history characteristics indicate that they are periodic strategists with associated population recruitment dynamics. Population genetic patterning varies among Pseudoplatystoma species, with some degree of homing behavior and genetic differentiation among populations, indicating the need for management by applying the Management Unit and perhaps Evolutionary Significant Unit concepts. The main threats to the persistence of these catfishes are overfishing and alterations in and obstruction of river flow due to the construction of hydropower dams. After synthesizing existing information on species of the genus Pseudoplatystoma, we offer suggestions for future research to fill critical gaps in the knowledge of this group. Full article