Growth Mechanism Research Articles

Sustainable scenarios in a plants–rhizobacteria–plant consumers system are in risk when biotic or abiotic factors change

The ecological relationship among plants, rhizobacteria and plant consumers has attracted the attention of researchers due to its implications in field crops. It is known that, the rhizosphere is occupied not only by rhizobacteria which grant benefits to the plants but also by bacteria which are detrimental for them. In this work, we construct and analyze a plants–rhizobacteria–plant consumers system. In the modeling process, it is assumed that there is a conditioned interaction between plants and bacteria in the rhizosfera such that there is a mutualistic relationship at low densities of rhizobacteria and the relationship is parasitic or competitive at higher densities of them. Benefits granted by rhizobacteria include mechanisms that increase the plant growth and defense mechanisms against plant consumers. From the analysis of the model and its simplified version, we show that scenarios of coexistence of all populations can occur for a wide range of values of the parameters which describe biotic or abiotic factors; however, these scenarios are in risk since scenarios of exclusion of species can occur simultaneously due to the presence of bistability phenomena. The results obtained can be useful for the decision makers to design interventions strategies on field crops when plant growth-promoting rhizobacteria are used.

High-speed shearing: An ultra-fast internal energy accumulation method for nucleation of SnZnO in photocatalysis

Zinc oxide (ZnO) nanoparticles and their derivatives, appreciated for their cost-effectiveness, simplicity in synthesis, and versatile applications, have garnered considerable attention. However, unraveling the nucleation and growth mechanisms of ZnO nanoparticles remains a formidable challenge. By comparing the magnetic stirring synthesis (MSS) and high-speed shearing (HSS) methods, we conducted time-dependent calculations of pressure and velocity at various positions in the solution. Under the powerful shearing force, which is the key route to accumulate internal energy (Ein), molecules could achieve at most 174 eV Ein in HSS instead of 0.81 eV Ein in MSS. Molecules could obtain enough energy for nucleation in just 1.03 μs. HSS, utilizing a high-speed rotor for robust shear forces, not only modifies nucleation patterns but also facilitates effective mixing in multi-element systems. SnxZn1−xO1+x nanoparticles prepared through HSS display uniform size, markedly reduced agglomeration, homogeneous element distribution, and a more pronounced bandgap change, causing a decrease in photocatalytic activity to the original 11.2 %.

Crystallization of Metallic Glasses and Supercooled Liquids.

This is an overview of recent findings on the structural changes observed upon heating, including crystallization processes in conventional metallic glasses, bulk metallic glasses, and their corresponding supercooled liquids. This paper encapsulates the various crystallization behaviors in metallic glasses by primary, eutectic, and polymorphous mechanisms, highlighting the complexity and diversity of the nucleation and growth mechanisms involved. Mechanically induced room-temperature crystallization is also discussed.

Constrained patterning of orientated metal chalcogenide nanowires and their growth mechanism

One-dimensional metallic transition-metal chalcogenide nanowires (TMC-NWs) hold promise for interconnecting devices built on two-dimensional (2D) transition-metal dichalcogenides, but only isotropic growth has so far been demonstrated. Here we show the direct patterning of highly oriented Mo6Te6 NWs in 2D molybdenum ditelluride (MoTe2) using graphite as confined encapsulation layers under external stimuli. The atomic structural transition is studied through in-situ electrical biasing the fabricated heterostructure in a scanning transmission electron microscope. Atomic resolution high-angle annular dark-field STEM images reveal that the conversion of Mo6Te6 NWs from MoTe2 occurs only along specific directions. Combined with first-principles calculations, we attribute the oriented growth to the local Joule-heating induced by electrical bias near the interface of the graphite-MoTe2 heterostructure and the confinement effect generated by graphite. Using the same strategy, we fabricate oriented NWs confined in graphite as lateral contact electrodes in the 2H-MoTe2 FET, achieving a low Schottky barrier of 11.5 meV, and low contact resistance of 43.7 Ω µm at the metal-NW interface. Our work introduces possible approaches to fabricate oriented NWs for interconnections in flexible 2D nanoelectronics through direct metal phase patterning.

Microwave plasma enhanced chemical vapor deposited vertical carbon nanoflakes electrodes for electric double layer capacitors

BackgroundAs energy storage materials are in an urgent demand and carbon-based nanomaterials provided great potential for battery and supercapacitor. This study applied microwave plasma enhanced chemical vapor deposition (MPE-CVD) to deposit 3-dimensional carbon nanoflakes (CNFs) with distinguished surface area to prepare the electrodes for electric double layer capacitors (EDLCs). MethodsThe vertical growth of CNFs is driven by MPE-CVD using CH4 as precursor gas. The as-prepared CNFs on titanium plate (CNFs_700/Ti) was optimized by thickness and mass loading as function of the applied power. Raman spectroscopy and field emission scanning electron microscopy analyzed the properties and surface morphology of carbon. The electrochemical properties of the CNFs_700/Ti assembled as Swagelok or pouch cell were evaluated by cyclic voltammetry and galvanostatic charge/discharge for potential developments in supercapacitor. Significant findingsAn unprecedented rapid growth rate of CNFs, 180 μm/h, was dramatically accelerated due to MPE-CVD procedure, and could be applied as electrode for EDLCs. The mechanism of CNFs growth was elucidated based on the temperature measurements in reactor which relates closely to the CNFs growth rate, proved by thickness and mass loading of CNFs. The clarification of CNFs growth mechanism assists future developments of carbon-based materials in energy storage materials.

Trace Pt-loading transition metal hydroxides as efficient catalyst for vaporized hydrogen peroxide decomposition

Vaporized hydrogen peroxide (VHP) holds great promise for the decontamination of space environment. Nevertheless, following the decontamination process, highly concentrated VHP within confined spaces is harmful to the human body. Hence, trace Pt-loading (0.57 wt%) transition metal hydroxides nanosheets anchored on Ni foam (Pt@NiAlCrFe-LDHs/NF) were prepared for VHP decomposition. Importantly, a strong electronic interaction between NiAlCrFe layer double hydroxides (NiAlCrFe-LDHs) and Pt was evidenced by XPS. Meanwhile, unique nanosheet-like morphology and rich mesoporous structure endow the catalyst with excellent performance. The catalytic activity of Pt@NiAlCrFe-LDHs/NF is approximately twice that of NiAlCrFe-LDHs/NF and seven times that of Pt/NF. The improved catalytic efficiency of Pt@NiAlCrFe-LDHs/NF results from the reduction in energy barrier for VHP decomposition reaction caused by the introduction of trace Pt. After ten recycling experiments, this catalyst still shows good durability with no significant deterioration in VHP decomposition efficiency. Finally, the growth mechanism of Pt@NiAlCrFe-LDHs/NF was also proposed and discussed.

Comparative study of sodium and potassium compounds as promoters for growth of monolayer MoS2 with high crystal quality on SiO2/Si substrate

Monolayer MoS2 is promising candidate for fabrication of optoelectronic devices due to its direct bandgap nature and high carrier mobility. Alkali metal compounds have been demonstrated to be helpful promoters for the growth of large single crystal monolayer MoS2 on SiO2/Si substrate. However, the catalytic mechanism of alkali metal compounds is still under debate. Herein, we compared the surface morphology, optical properties, and electrical properties of monolayer MoS2 flakes grown on SiO2/Si substrate assisted by promoters containing potassium or sodium cations and halogen (chlorine) or non-halogen (hydroxide) anions, i.e. NaCl, NaOH, KCl and KOH. Based on the analysis of existing growth mechanism, we proposed that the alkali metal cation, plays a dominant role in promoting the lateral growth of monolayer MoS2 and obtaining high crystal quality. Furthermore, potassium has a greater promoting effect than sodium. By optimizing growth conditions, monolayer triangular MoS2 flakes with large lateral size over 160 μm were grown assisted by KCl promoter. Raman and PL spectra verified excellent crystal quality of the flakes, with typical electron mobilities of 2.98 and 20 cm2 V−1 s−1 for the back-gated filed effect transistors fabricated on as-grown and fresh SiO2/Si substrates, respectively.

Site-Selective Synthesis of Bilayer Graphene on Cu Substrates Using Titanium as a Carbon Diffusion Barrier.

Chemical vapor deposition (CVD) is a widely used method for graphene synthesis, but it struggles to produce large-area uniform bilayer graphene (BLG). This study introduces a novel approach to meet the demands of large-scale integrated circuit applications, challenging the conventional reliance on uniform BLG over extensive areas. We developed a unique method involving the direct growth of bilayer graphene arrays (BLGA) on Cu foil substrates using patterned titanium (Ti) as a diffusion barrier. The use of the Ti layer can effectively control carbon atom diffusion through the Cu foil without altering the growth conditions or compromising the graphene quality, thereby showcasing its versatility. The approach allows for targeted BLG growth and achieved a yield of 100% for a 10 × 10 BLG units array. Then a 10 × 10 BLG memristor array was fabricated, and a yield of 96% was achieved. The performances of these devices show good uniformity, evidenced by the set voltages concentrated around 4 V, and a high resistance state (HRS) to low resistance state (LRS) ratio predominantly around 107, reflecting the spatial uniformity of the prepared BLGA. This study provides insight into the BLG growth mechanism and opens new possibilities for BLG-based electronics.

Microstructure, mechanical properties and interfacial features of graphene oxide reinforced 7075 composites fabricated by ultrasonic assisted casting

Graphene oxide reinforced 7075 (GO/7075) composites were successfully prepared via ultrasonic assisted casting. In this study, the microstructure, mechanical properties and interfacial structure of GO/7075 composites with varying GO contents were investigated. The experimental results showed that GO could refine grain size and produce many dislocations at the GO/Al interface, and was well bonded with Al matrix. Meanwhile, a few rod-like Al4C3 phases were observed at the active prism planes of GO in the composite. When the content of GO reached 1.0 wt%, the optimal mechanical properties of GO/7075 composites were obtained. The yield strength and ultimate tensile strength of 1.0 wt% GO/7075 composites were 212.3 MPa and 285.6 MPa, which were 61.8 % and 41.1 % higher than those of 7075 alloy, respectively. The thermal mismatch strengthening and load transfer strengthening were the main strengthening mechanisms. Moreover, in order to control the interfacial reaction between GO and Al matrix, the thermodynamic/kinetic condition and growth mechanism for the formation of Al4C3 were analyzed in details.

Growth mechanism of high-aspect ratio zirconia whisker by molten salt method

Growth mechanism of high-aspect ratio zirconia whisker by molten salt method

Efficient eco-friendly synthesis of carbon nanotubes over graphite nanosheets from yellow corn: a one-step green approach

The present work reports the synthesis of multi-wall carbon nanotubes (MWCNTs) over graphite nanosheets by an easy and simple approach without using any external catalyst. Simply, yellow corn seeds were thermally annealed in a hydrogen atmosphere at 1050 °C for 3 h without any pretreatments. Notably, the growth of MWCNTs was observed to preferentially occur on the outer surface of the corn shell. This uncomplicated approach not only emphasizes the feasibility of synthesizing carbon nanomaterials using agricultural by-products but also underscores the potential applications of these synthesized materials in various fields. Samples were examined through a comprehensive analysis employing various techniques, including scanning electron microscopy (SEM), Raman spectroscopy, FTIR, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The findings unveiled the formation of rolled graphene accompanied by the presence of vertical multi-wall carbon nanotubes (MWCNTs) positioned over stacked graphene sheets. This detailed characterization provides insights into the structural features and arrangement of the synthesized materials, paving the way for a deeper understanding of their potential applications. The pyrolysis temperature is a crucial factor in the morphological characteristics of the synthesized carbon nanostructures. While graphene cage-like structures were obtained at 800 °C, small carbon nanotubes were grafted to larger ones and formed three-dimensional hierarchical morphologies when the annealing temperature increased to 900 °C. The growth mechanism of the carbon nanotubes was explained based on the jet self-extrusion of the generated gases through the inherent pores of the corn seeds. The current technique employed in manufacturing MWCNTs shows significant promise as a green synthesis method for producing catalyst-free MWCNTs suitable for industrial applications including sensors and energy storage materials.

Multi‐Interfacial Heterostructure Design of Carbon Fiber/Silicone Rubber‐Oriented Composites for Microwave Absorption and Thermal Management

AbstractIn order to ensure the operation and longevity of electronic devices, the design of multifunctional composites integrating microwave absorption (MA) and thermal conduction has become the key to solving the problem. However, the superior MA properties and thermal conductivity are usually incompatible in the blend system. In this study, a modified carbon fiber/silicone rubber‐oriented structure is designed based on the multiscale design concept of heterostructures with multiple interfaces. The forward deposition‐reverse growth mechanism is utilized at the microscopic level to construct multi‐interfacial heterogeneous structures on the surface of 1D carbon fibers (CFs). The magneto‐electric coupling network of the multi‐interfacial heterostructure induces interfacial polarization and enhances MA properties and heat transfer. Subsequently, the structural design of the modified CFs is carried out on a macroscopic scale using the ice template method. The directionally aligned modified CFs/silicone rubber aerogel composites are obtained by backfilling with silicone rubber (SR). The samples achieved an effective absorption bandwidth of 4.41 GHz and a maximum reflection loss of −42.29 dB with ultra‐thin thickness (1.3 mm). The thermal conductivity of the sample is improved to 200% compared to pure silicone rubber. The composites with directional alignment have promising applications in lightweight and flexible electronic packaging.

Superselective Angiography of Vasa Vasorum Within Partially Thrombosed Vertebral Aneurysm: A Case Report.

Partially thrombosed vertebral artery aneurysms (PTVAs) are rare, most of which are not easy to treat. Furthermore, endovascular treatment of PTVAs may not have favorable outcomes. The relationship between PTVAs and well-developed vasa vasorum (VV), including the mechanism of aneurysm growth, has been reported, but there are no reports of imaging findings by digital subtraction angiography (DSA). In this case, we successfully performed superselective angiography of well-developed VV and evaluated its imaging characteristics. We present the first DSA report of a well-developed VV of PTVA. A 54-year-old patient presented with a PTVA that exerted a mass effect on the medulla oblongata. The aneurysm had no cavity due to thrombosis. The 3-dimensional DSA images indicated VV. Superselective angiography of the VV indicated staining of the thrombosed aneurysm and draining into the suboccipital cavernous sinus through the venous VV. Thus, VV embolization with n-butyl cyanoacrylate was performed. After 3 months, the contrast effect of the aneurysm on contrast-enhanced magnetic resonance imaging disappeared and aneurysm shrinkage was observed. We successfully identified a VV within PTVA. Superselective VV angiography showed staining of the thrombosed component and venous return draining into the suboccipital cavernous sinus. In this case, the embolization of the VV proved to be an effective endovascular treatment of PTVA, but the safety of this method is a challenge. Further case studies are required to validate this method, and we hope it will evolve into a new treatment of PTVA.

Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles.

Iron oxide nanoparticles (IONPs) arewidely used for biomedical applications due to their unique magnetic properties and biocompatibility. However, the controlled synthesis of IONPs with tunable particle sizes and crystallite/grain sizes to achieve desired magnetic functionalitiesacross single-domain and multi-domain size ranges remains an important challenge. Here, a facile synthetic method is used to produceiron oxide nanospheres (IONSs) with controllable size and crystallinity for magnetic tunability. First, highly crystalline Fe3O4 IONSs (crystallite sizes above 24nm) having an averagediameter of 50 to 400nm are synthesized with enhanced ferrimagnetic properties. The magnetic properties of these highly crystalline IONSs are comparable to those of their nanocube counterparts, whichtypically possess superior magnetic properties. Second, the crystallite size can be widely tuned from 37 to 10nm while maintaining the overall particle diameter, thereby allowing precise manipulation from the ferrimagnetic to the superparamagnetic state. In addition, demonstrations of reaction scale-up and the proposed growth mechanism of the IONSs are presented. This study highlights the pivotal role of crystal size in controlling the magnetic properties of IONSs and offers a viable means to produce IONSs with magnetic properties desirable for wider applications in sensors, electronics, energy, environmental remediation, and biomedicine.

Real-Time Observation for MoS2 Growth Kinetics and Mechanism Promoted by the Na Droplet.

While the molten salt-catalyzed chemical vapor deposition (CVD) technique is recognized for its effectiveness in producing large-area transition metal chalcogenides, understanding their growth mechanisms involving alkali metals remains a challenge. Here, we investigate the kinetics and mechanism of sodium-catalyzed molybdenum disulfide (MoS2) growth and etching through image analysis conducted using an integrated CVD microscope. Sodium droplets, agglomerated via the thermal decomposition of the sodium cholate dispersant, catalyze the precipitation of supersaturated MoS2 laminates and induce growth despite fragmentation during this process. Triangular MoS2 crystals display a distinct self-exhausting exponential behavior and slow growth of thermodynamically favorable crystallographic faces, exhibiting a sulfur-dominant pressure. The growth and etching processes are facilitated by the scooting of sodium droplets along grain edges, displaying comparable rates. Leveraging these kinetics makes it possible to engineer atypical MoS2 shapes. This combined microscope not only enhances the understanding of growth mechanisms but also contributes to the facile development of next-generation nanomaterials.

Comprehensive Analysis of Placental DNA Methylation Changes and Fetal Birth Weight in Pigs.

Birth weight is a complex multifactorial trait relevant to health states and disease risks in later life. The placenta is essential for proper fetal growth and facilitates gas, nutrient, and waste exchange between the mother and developing fetus. How changes in placental DNA methylation affect fetal birth weight remains to be fully elucidated. In this study, we used whole-genome bisulfite sequencing and RNA sequencing to reveal a global map of DNA methylation and gene expression changes between the placentas of highest birth weight and lowest birth weight piglets in the same litters. The transcriptome analysis identified 1682 differential expressed genes and revealed key transcriptional properties in distinct placentas. We also identified key transcription factors that may drive the differences in DNA methylome patterns between placentas. The decrease in DNA methylation level in the promoter was associated with the transcriptional activation of genes associated with angiogenesis, extracellular matrix remodeling, and transmembrane transport. Our results revealed the regulatory role of DNA methylation in gene transcription activity leading to the differences in placental morphological structures and birth weights of piglets. These results could provide novel clues to clarify the underlying regulatory mechanisms of placental development and fetal growth.

Application of CuNPs and AMF alleviates arsenic stress by encompassing reduced arsenic uptake through metabolomics and ionomics alterations in Elymus sibiricus

Recent studies have exhibited a very promising role of copper nanoparticles (CuNPs) in mitigation of abiotic stresses in plants. Arbuscular mycorrhizae fungi (AMF) assisted plants to trigger their defense mechanism against abiotic stresses. Arsenic (As) is a non-essential and injurious heavy-metal contaminant. Current research work was designed to elucidate role of CuNPs (100, 200 and 300 mM) and a commercial inoculum of Glomus species (Clonex® Root Maximizer) either alone or in combination (CuNPs + Clonex) on physiology, growth, and stress alleviation mechanisms of E. sibiricus growing in As spiked soils (0, 50, and 100 mg Kg− 1 soil). Arsenic induced oxidative stress, enhanced biosynthesis of hydrogen peroxide, lipid peroxidation and methylglyoxal (MG) in E. sibiricus. Moreover, As-phytotoxicity reduced photosynthetic activities and growth of plants. Results showed that individual and combined treatments, CuNPs (100 mM) as well as soil inoculation of AMF significantly enhanced root growth and shoot growth by declining As content in root tissues and shoot tissues in As polluted soils. E. sibiricus plants treated with CuNPs (100 mM) and/or AMF alleviated As induced phytotoxicity through upregulating the activity of antioxidative enzymes such as catalase (CAT) and superoxide dismutase (SOD) besides the biosynthesis of non-enzymatic antioxidants including phytochelatin (PC) and glutathione (GSH). In brief, supplementation of CuNPs (100 mM) alone or in combination with AMF reduced As uptake and alleviated the As-phytotoxicity in E. sibiricus by inducing stress tolerance mechanism resulting in the improvement of the plant growth parameters.

Striated muscle: an inadequate soil for cancers.

Many organs of the body are susceptible to cancer development. However, striated muscles-which include skeletal and cardiac muscles-are rarely the sites of primary cancers. Most deaths from cancer arise due to complications associated with the development of secondary metastatic tumours, for which there are few effective therapies. However, as with primary cancers, the establishment of metastatic tumours in striated muscle accounts for a disproportionately small fraction of secondary tumours, relative to the proportion of body composition. Examining why primary and metastatic cancers are comparatively rare in striated muscle presents an opportunity to better understand mechanisms that can influence cancer cell biology. To gain insights into the incidence and distribution of muscle metastases, this review presents a definitive summary of the 210 case studies of metastasis in muscle published since 2010. To examine why metastases rarely form in muscles, this review considers the mechanisms currently proposed to render muscle an inhospitable environment for cancers. The "seed and soil" hypothesis proposes that tissues' differences in susceptibility to metastatic colonization are due to differing host microenvironments that promote or suppress metastatic growth to varying degrees. As such, the "soil" within muscle may not be conducive to cancer growth. Gaining a greater understanding of the mechanisms that underpin the resistance of muscles to cancer may provide new insights into mechanisms of tumour growth and progression, and offer opportunities to leverage insights into the development of interventions with the potential to inhibit metastasis in susceptible tissues.

An Enigmatic Soft-Tissue Creeping Phenomenon: The Spontaneous Peri-Implant Mucosa Margin and Papilla Growth, Part Two-A Scientifically Supported Hypothesis Article.

In our previous article, we observed and measured a spontaneous growth in the coronal direction of the keratinized tissues present around implants. This growth involved both free margins and interdental papillae, and we indicated our hypothesis on the probable cause of this still-unexplained phenomenon. The growth of oral soft tissues involves several other structures, such as the linea alba and tongue indentation. Our idea holds that growth of these tissues is generated by the negative intraoral pressure created in the oral phase of swallowing and the subsequent resting position, which through the resulting suction causes a shift of these soft structures in the gaps around the dental crowns. Other hypotheses have been suggested in the past to understand this phenomenon of soft tissue growth, which still lacks data supporting etiological evidence. The purpose of this article is to thoroughly analyze and verify our model by comparing the clinical observations with citations and examples from the literature, combined with notions of physiology, biology, and physics that help in clarifying these events. To better explain the mechanisms of oral soft tissue growth, photographs of clinical cases paradigmatic of the phenomenon are shown.

On Morphology of Aluminum-Gallium Nitride Layers Grown by Halide Vapor Phase Epitaxy: The Role of Total Reactants' Pressure and Ammonia Flow Rate.

The focus of this study was the investigation of how the total pressure of reactants and ammonia flow rate influence the growth morphology of aluminum-gallium nitride layers crystallized by Halide Vapor Phase Epitaxy. It was established how these two critical parameters change the supersaturation levels of gallium and aluminum in the growth zone, and subsequently the morphology of the produced layers. A halide vapor phase epitaxy reactor built in-house was used, allowing for precise control over the growth conditions. Results demonstrate that both total pressure and ammonia flow rate significantly affect the nucleation and crystal growth processes which have an impact on the alloy composition, surface morphology and structural quality of aluminum-gallium nitride layers. Reducing the total pressure and adjusting the ammonia flow rate led to a notable enhancement in the homogeneity and crystallographic quality of the grown layers, along with increased aluminum incorporation. This research contributes to a deeper understanding of the growth mechanisms involved in the halide vapor phase epitaxy of aluminum-gallium nitride, and furthermore it suggests a trajectory for the optimization of growth parameters so as to obtain high-quality materials for advanced optoelectronic and electronic applications.