Growth Process Research Articles

Adaptable Alchemy: Exploring the Flexibility of Specialized Metabolites to Environmental Perturbations Through Post-Translational Modifications (PTMs)

Plants are subjected to various stresses during the growth process, including biotic stresses, as well as abiotic stresses such as temperature, drought, salt, and heavy metals. To cope with these biotic and abiotic adversities, plants have evolved complex regulatory mechanisms during their long-term environmental adaptations. In a suddenly changing environment, protein modifiers target other proteins to induce post-translational modification (PTM) in order to maintain cell homeostasis and protein biological activity in plants. PTMs modulate the activity of enzymes and transcription factors in their respective metabolic pathways, enabling plants to produce essential compounds for their survival under stress conditions. Examples of post-translational mechanisms include phosphorylation, ubiquitination, glycosylation, acetylation, protein–protein interactions, and targeted protein degradation. Furthermore, the role of histone modifications in regulating secondary metabolism deserves attention due to its potential impact on heritability and its contribution to stress tolerance. Understanding the epigenetic aspect of these modifications can provide valuable insights into the mechanisms underlying stress response. In this context, also examining PTMs that impact the biosynthesis of secondary metabolites is meaningful. Secondary metabolites encompass a wide range of compounds such as flavonoids, alkaloids, and terpenoids. These secondary metabolites play a crucial role in plant defense against herbivores, pathogens, and oxidative stress. In this context, it is imperative to understand the contribution of secondary metabolism to plant tolerance to abiotic stresses and how this understanding can be leveraged to improve long-term survival. While many studies have focused on the transcriptional regulation of these metabolites, there is a growing interest in understanding various changes in PTMs, such as acetylation, glycosylation, and phosphorylation, that are able to modulate plants’ response to environmental conditions. In conclusion, a comprehensive exploration of post-translational mechanisms in secondary metabolism can enhance our understanding of plant responses to abiotic stress. This knowledge holds promise for future applications in genetic improvement and breeding strategies aimed at increasing plant resilience to environmental challenges.

Rapid bioreactor process optimization and scale-up for production of a measles vector COVID-19 vaccine candidate.

The emergence of SARS-CoV-2 in late 2019 and subsequent worldwide spread and pandemic in 2020 spurred the rapid and agile development of a variety of vaccine candidates. With speed to patients in mind during development of measles-vectored vaccine candidate V591, process optimization efforts were made to expand options for raw material sourcing/treatment, enable flexible use of various types of processing equipment, and streamline the overall production process. To that end, both gamma irradiated and heat sterilized microcarriers were tested to expand the supply network for critical process development experiments and manufacturing at a time when worldwide supply chains were strained or disrupted. Single use bioreactors were also evaluated and implemented to reduce experimental turnaround time. Furthermore, to simplify the process and gain additional efficiencies in large scale media preparation, growth and infection media formulations were harmonized with a parallel vaccine development program. These rapid process option evaluations were conducted parallel to critical path scale up, and the combined efforts enabled the rapid demonstration of two full manufacturing scale 2000 L bioreactors less than 6 months after virus seed delivery, culminating in the first large scale measles production process capable of addressing the high dose demands of a pandemic response scenario. Despite subsequent clinical discontinuation of the V591 vaccine candidate, the findings described herein will be useful for enabling rapid and scalable production of other measles-vectored vaccine candidates, oncolytic measles strains, or cell and gene therapies.

РОЛЬ ГУМИНОВЫХ УДОБРЕНИЙ И РЕГУЛЯТОРОВ РОСТА ПРИ ВЫРАЩИВАНИИ ТЫСЯЧЕЛИСТНИКА ОБЫКНОВЕННОГО В УСЛОВИЯХ ЗАПАДНОГО ПРЕДКАВКАЗЬЯ

The purpose of the study is to develop methods for increasing the yield of yarrow and increasing the content of essential oil in medicinal raw materials. A study of the effect of humic fertilizers on the productivity of common yarrow in the 2nd–4th growing season was carried out in the North Caucasus branch of the Federal State Budgetary Institution VILAR in 2021–2022. The soil of the experimental plot is represented by leached chernozems, which have a neutral reaction, pH is about 7. The humus content in the arable layer is 5.0 %; total nitrogen – 0.22–0.30; phosphorus (P2O5) – 9.17–10.22; potassium (K2O) – 1.7–2.1 %. Weather conditions (amount of precipitation and temperature) were favorable for the growth and development of plants. Research was conducted by setting up small-plot experiments, which were carried out in accordance with generally accepted methods. The effect of foliar treatments with humic fertilizers Lignohumat (0.5 l/ha), Normat L (0.3 kg/ha) and their complexes with the bioregulator Zircon (0.1 l/ha) on growth and development was studied plants, yield of raw materials and essential oil content. Treatment with humates was carried out at the beginning of plant growth and during the stemming phase. Double application of humic fertilizers Lignohumat (0.5 l/ha) and Normat L (0.3 kg/ha) contributed to the intensification of growth processes, an earlier onset (by 2–4 days) of the budding and flowering phases, and made it possible to obtain increase in yield of raw materials by 20–25 %, essential oil per unit area – 25–32 %, but the content of essential oil increased slightly – by 2–5 %. It can be increased (by 26–30 %) by treating plants during the budding phase with the growth regulator Zircon (0.1 l/ha). The complex use of humic preparations during the phase of intensive growth and Zircon at the onset of flowering leads to an increase in the yield of essential oil per hectare to 48 %.

Remote sensing-based maize growth process parameters revel the maize yield: a comparison of field- and regional-scale

The accurate estimation of regional crop yields holds significant importance for optimizing subsequent resource allocation and maximizing economic returns in agriculture. Crop yield can be effectively estimated by assessing the overall growth status through long-term remote sensing observations. However, most previous studies have relied on remote sensing data from one or a few periods for yield estimation, thus lacking a comprehensive description of entire crop growth. Furthermore, past algorithms have not considered their applicability across different observational scales (e.g., unmanned aerial vehicle (UAV)- and satellite-observed). Considering this, we extracted four maize growth process parameters using Leaf Area Index (LAI) obtained from UAV (equipped with multispectral sensor, centimeter-level) and satellite (MODIS, 1 km) observations: PP_a (representing the duration of the crop growth period), PP_b (representing the peak growth stage of the crop), PP_c (representing the initial state of the crop), and LAImax (maximum LAI). These parameters were used to construct a maize yield estimation model applicable at both regional and field scales. The results indicate that the four process parameters extracted in this study can accurately estimate crop yields, with rRMSE = 14.08% at the field-scale and rRMSE = 17.75% at the regional-scale. Among these parameters, PP_a, representing the duration of the crop growth period, and the maximum LAI, are the parameters that individually contribute the most to the estimation accuracy. Moreover, the proposed method exhibited good spatial applicability (field-scale: Moran Index (MI) = -0.18; regional-scale: MI = 0.19). In conclusion, the parameters describing maize growth process derived from long-term-series observations can effectively estimate maize yield across different observation scales. This method not only facilitates the optimization of agronomic practices based on UAV observations but also supports the decision of regional agricultural policies based on satellite observations. Furthermore, crop yield estimation utilizing process-based parameters provides a new perspective for related studies.

ВЫЗРЕВАНИЕ РАСТЕНИЙ ДЛЯ СОЗДАНИЯ КОЛЛЕКЦИИ ВИНОГРАДА IN VITRO

The purpose of the study is to develop a method for creating a collection of the grape gene pool in vitro using the combined use of biotechnological methods: modification of the nutrient medium and cultivation of plants under conditions of low positive temperature. During the cultivation process with an increased content of sucrose in the nutrient medium (50−70 g/l), autumn color of the leaves appears and shoots ripen in various grape varieties: Sypun Cherniy, Vierul, Tsimlyansky Cherniy (clone 2–3), Cabernet Sauvignon, Kumshatsky, Rupestris du Lo, Tsimladar, less in varieties Krasnostop zolotovsky, Baklanovsky, Sibirkovy. This helped to extend the period of non-transplant storage of plants. The fairly high viability of plants at a sucrose concentration of 70.0 g/l during the first 5 months of cultivation gradually decreased when they were cultivated for 8–9 months. The possibility of in vitro regeneration of plants from mature microcuttings when cultivated for one year has been established. To increase the safety and viability of plants, matured test tube plants were stored in a pharmaceutical cabinet at a low positive temperature of 1−8 °C. Plants were stored in tightly closed tubes on solid culture medium. When stored under these conditions for 3–4 years, the plants had a length of the mature part of the shoots of 49.8−70.3 %. Better ripening compared to native ones occurs in interspecific grape varieties and rootstocks. After a month of cultivating lignified microcuttings with living tissues on the solid nutrient medium of Murashige and Skuga, single shoot regeneration and plant restoration were revealed. Cultivation of the restored plants under standard conditions on solid nutrient medium Murashige and Skuga with the addition of the growth regulator Melafen for 3 months contributed to further regeneration and improvement of growth processes of both roots and shoots. The plants were completely restored. The possibility of continuous storage of test tube grape plants for 3−4 years has been proven with a combination of two factors: an increased concentration of sucrose in the nutrient medium and a low positive temperature of 1−8 °C.

Rooted in Communication: Exploring Auxin-Salicylic Acid Nexus in Root Growth and Development.

Plant hormones are pivotal in orchestrating diverse aspects of growth and developmental processes. Among various phytohormones, auxin and salicylic acid (SA) stand out as important regulators, often exerting opposing effects on overall plant growth. Essentially, research has indicated that auxin and SA-mediated pathways exhibit mutual antagonism during pathogen challenge. Additionally, in recent years, significant advancements have been made in uncovering the molecular intricacies that govern the action and interplay between these two phytohormones during various essential growth-related processes. In this discussion, we briefly delve into the genetic and molecular mechanisms involved in auxin and SA antagonism. We then analyse in detail how this dialogue impacts critical aspects of root development, with an emphasis on the transcriptional and protein regulatory networks. Finally, we propose the potential of exploring their interaction in various other aspects of below ground root growth processes. Understanding this relationship could provide valuable insights for optimizing and enhancing crop growth and yields.

Pantoea–Bacillus as a Composite Microbial Community: Inhibition and Potential Mechanism Against Potato Anthracnose Disease

The potato (Solanum tuberosum), an important component of global food security, often faces threats from various diseases during its growth process, especially potato anthracnose (Colletotrichum coccodes), which severely affects crop yield and quality. In this study, we successfully isolated and identified two bacteria with potential for biological control, (Pantoea agglomerans) and (Bacillus subtilis).The experimental results indicate that the bacterial suspensions of strains JZ-1-1-1 and JZ-2-2-2 had a significant inhibitory effect on the pathogen ZL-7, with the inhibition rate of JZ-1-1-1 reaching as high as 55.21%. The inhibition rate of JZ-2-2-2 was 53.48%. When these two strains were mixed at a 4:6 ratio, the inhibitory effect on pathogenic bacteria was even more significant, reaching 68.58% inhibition. In addition, the composite microbial community produced biofilms with their yield gradually increasing within 24 h and showing a slight decrease after 72 h. The efficacy test further indicated that the composite bacterial suspension was highly effective in controlling the spread of lesions, with an efficacy rate as high as 81.40%. In the analysis of defense enzyme activity, peroxidase (POD) and superoxide dismutase (SOD) levels peaked on day seven, while the composite bacterial suspension significantly reduced malondialdehyde (MDA) and polyphenol oxidase (PPO) activity. Quantitative real-time PCR confirmed that these two strains effectively colonized the surface of potato tubers. In summary, this study provides an important theoretical basis and practical guidance for the application of biological methods for the prevention and control of potato anthracnose.

Dynamic analysis of a stochastic microorganism flocculation model with two complementary nutrients and nonlinear perturbation

This paper considers a stochastic model of microorganism flocculation incorporating two complementary nutrients. By introducing nonlinear perturbation, we analyze the influence of flocculations, microorganisms, and two nutrients on the model dynamic. The paper proves the existence and uniqueness of the stationary distribution in the stochastic model. Moreover, sufficient conditions for the extinction of microorganisms are established. Numerical simulations indicate that nonlinear perturbation makes the growth process of microorganisms more unpredictable, better reflecting the complicated variations in real-world environments. Noise interference is not always detrimental, but appropriate noise levels may promote the growth of microorganisms.

Insights into Molecular Mechanism of Secondary Xylem Rapid Growth in Salix psammophila

Salix psammophila C. Wang & C. Y. Yang is an important windbreak and sand-fixing shrub species in Northwest China, with excellent characteristics such as resistance to drought, wind, and sand. S. psammophila needs to be stubbed flat after several years of growth to continue to grow, otherwise, its growth rate will slow down and even begin to die. To understand the genetic regulatory mechanism of secondary growth in S. psammophila, cell structure and transcriptome analysis were performed on the secondary xylem and secondary phloem of stems. The results showed that the secondary xylem and the secondary phloem of S. psammophila were well developed at 1, 2, and 3-year-old stages, and the secondary growth changes mainly occurred in the secondary xylem at the 2 to 3-year-old stage, with a faster growth rate. The CSE2 and CSE1 genes that regulate CSE (caffeoyl shikimate esterase) have high sequence similarity (92% and 93%) with the CSE2 and CSE1 genes of the genus Populus, respectively, and regulate lignin biosynthesis. Notably, the expression levels of these two genes decreased in the secondary xylem of 3-year-old S. psammophila, indicating that the rapid growth of S. psammophila may be related to lignin biosynthesis. Weighted gene co-expression network analysis (WGCNA) was utilized to screen candidate TFs and genes involved in the secondary growth processes of S. psammophila, which were categorized into six co-expression modules. A total of 79 genes were selected from these co-expression modules, and co-expression network maps of the genes were constructed. The results indicate that the secondary growth of S. psammophila was regulated by a TF regulatory network. Interestingly, PLATZ TFs were involved in the rapid secondary growth and stress tolerance in S. psammophila. This hints that S. psammophila may promote secondary growth by increasing stress tolerance.

Thermal evolution of solid solution of silica-embedded AgPt alloy NPs in the large miscibility gap.

Understanding the phase behavior of immiscible elements in bimetallic nanomaterials is essential for controlling their structure and properties. At the nanoscale, the miscibility of these immiscible elements often deviates from their behavior in bulk materials. Despite its significance, comprehensive and quantitative experimental insights into the dynamics of the immiscible-to-miscible transition, and vice versa, remain limited. In this study, we investigate the nucleation and growth kinetics of silica-embedded AgPt nanoparticles (NPs) across a wide range of annealing temperatures (25 °C to 900 °C) to elucidate temperature-dependent nanoalloy phase transitions and NP size distribution. Our findings reveal that the alloy phase persists up to 400 °C, with a corresponding average NP size of ∼2 nm. Beyond this temperature, phase instability begins to occur. We propose a three-stage process of nucleation and growth: (1) initial AgPt nanoalloy formation during deposition, (2) growth via thermal energy-assisted diffusion up to 400 °C, and (3) Ag atom emission from the nanoalloy above 500 °C, indicating Ag diffusion towards the surface, followed by partial sublimation of Ag atoms at 900 °C. These results provide crucial insights into the thermal limits for the dealloying of NPs, growth kinetics, and phase stability or instability under varying thermal conditions.

Mechanism and Structural Defects of Zinc Film Deposited on a Copper Substrate: A Study via Molecular Dynamics Simulations

Epitaxial growth can be used to guide the controllable growth of one metal on the surface of another substrate by matching the interface lattice, thus improving the dendrite tendency of metal growth. The atomic arrangement of the Cu (111) crystal plane of the FCC structure is similar to that of the Zn (0002) crystal plane of the HCP structure, which is theoretically expected to promote the heterogeneous epitaxial nucleation growth of metal zinc under low strain. In this paper, the molecular dynamics method is used to simulate the atomic process of zinc film growth on the Cu (111) surface. It is found that the behavior of zinc-adsorbed atoms on the substrate surface conforms to the epitaxial growth mode. The close-packed structure grown along the (0002) direction of the layered clusters is tiled on the Cu (111) surface, forming a highly ordered low-lattice-mismatch interface. When a large area of layered zinc clusters cover the substrate, the growth mode will change from heteroepitaxial growth to homoepitaxial growth of Zn atoms on the zinc film, forming a lamellar distribution composed of FCC and HCP structure grains. Polycrystalline zinc film with a planar structure with a (0002) surface preferred a crystal plane. The increase in incident energy is helpful in improving the quality of zinc films, while the deposition rate, corresponding to the deposition temperature and electrolyte ion concentration, has no significant effect on the surface morphology and crystal structure of single metal films. In summary, the atomic arrangement of the Cu (111) surface has a strong guiding effect on the atomic ordered arrangement in the zinc film crystal, which is suitable for the epitaxial deposition of the substrate to induce the ordered growth of the Zn (0002) crystal plane.

Effects of feeding varying levels of mycotoxin-containing corn fines on diet choice and growth performance of nursery pigs

Abstract Mycotoxins in feed are known to negatively affect growth and other physiological processes in pigs. Two experiments were conducted to investigate the effects of feeding diets with varying levels of mycotoxins and boron (a nutrient reported to mitigate some aspects of mycotoxicosis). Screenings from the 2020 crop year corn contained mycotoxin levels of 23,038 ppb total fumonisins (FUM), 1,446 ppb zearalenone (ZEA), and 5,032 ppb total deoxynivalenol (DON). The corn fines were added to a corn-soybean meal diet formulated to meet or exceed NRC (2012) nutrient requirements as a replacement for corn at 0, 10, and 20% for Diets 1-3. Diets 4-6 were Diets 1-3, respectively, plus 40 ppm boron from sodium tetraborate decahydrate. Diets 3 and 6 were formulated to approximate the guidance level of fumonisin and the advisory level of DON stated by the FDA. Exp. 1 used 48 crossbred pigs (initial body weight [BW] = 9.18 kg ± 0.12 kg) blocked by sex and BW and randomly allotted to 1 of 3 treatment comparisons: Comparison 1) Diet 1 vs. Diet 2; Comparison 2) Diet 1 vs. Diet 3; and Comparison 3) Diet 2 vs. Diet 3. There were 4 replicates (4 pigs/pen) for the 21-day preference trial. Exp. 2 used 144 crossbred pigs (mean initial BW = 10.20 ± 0.23 kg) blocked by sex and BW and randomly allotted to diets for a total of 6 replicates (4 pigs/pen) for a 21-day growth trial. On d 21, serum was collected from the heaviest and lightest pig in each pen for clinical chemistry assessment. Exp. 1 demonstrated the barrows’ ability to discern between diets in Comparisons 2 and 3 (P < 0.01) for each week while gilts only started to exhibit that ability during Week 3 for Comparison 2 (P = 0.06). Increasing mycotoxin levels in Exp. 2 had no effect on overall ADG, ADFI, and G:F (P = 0.16, 0.53, and 0.92, respectively). The increasing mycotoxin levels affected serum glucose and cholesterol (P = 0.03, and P < 0.01, respectively). There was no effect of boron on the same performance measures (P = 0.81, 0.59, and 0.76, respectively) although it did lower serum glucose (P = 0.02). In conclusion, pigs can differentiate and choose between diets containing these mixed mycotoxins but when not given a choice, the pigs do not necessarily have different growth performance using the particular mycotoxins and concentrations within the framework of this assessment.

Data-Driven Soft Sensor Model Based on Multi-Timescale Feature Fusion for Crystal Quality Prediction in Czochralski Process

The accurate real-time prediction of the crystal quality index v/G is an important reference for the real-time monitoring of the growth quality status and the process optimization adjustment of semiconductor silicon single crystals. This paper proposes a data-driven crystal quality indicator v/G soft sensor prediction model based on multi-timescale feature fusion to achieve the effective prediction of the crystal quality indicator v/G. Firstly, the characteristics of the crystal quality index v/G in the growth process of Czochralski silicon single crystal are analyzed. Secondly, the crystal quality index v/G is broken down into several natural components using something called complete ensemble empirical mode decomposition with adaptive noise (CEEMDAD), which provides more stable data. On this basis, each intrinsic mode component is reconstructed according to the sample entropy. Then, the maximum mutual information coefficient (MIC) method is applied to identify the characteristic variables most closely associated with each reconstructed component of the crystal quality index v/G from the process-influencing factors. Then, a long short-term memory network with a self-attention mechanism is used to establish a prediction model of the reconstructed components to extract the multi-timescale feature information from the different components of the crystal quality index v/G. Finally, the prediction results of the crystal quality index v/G are obtained by fusing each subsequent prediction model. According to the actual field data, the comprehensive experimental results validate the efficacy of the proposed soft sensor modeling method for the crystal quality index v/G. Compared with the single model, the proposed prediction model has a smaller MAE, RMSE, and prediction performance index and a higher HR prediction hit rate.

Direct observations of nucleation and early-stage growth of Au-catalyzed GaAs nanowires on Si(111)

Developing a reliable procedure for the growth of III-V nanowires (NW) on silicon (Si) substrates remains a significant challenge, as current methods rely on trial-and-error approaches with varying interpretations of critical process steps such as sample preparation, Au-Si alloy formation in the growth reactor, and NW alignment. Addressing these challenges is essential for enabling high-performance electronic and optoelectronic devices that combine the superior properties of III-V NW semiconductors with the well-established Si-based technology. Combining conventional scalable growth methods, such as metalorganic chemical vapor deposition (MOCVD) within situcharacterization using environmental transmission electron microscopy (ETEM-MOCVD) enables a deeper understanding of the growth dynamics, if that knowledge is transferable to the scalable processes. We report on successful epitaxial growth of Au-catalyzed GaAs NWs on Si(111) substrates using micro-electromechanical system chips with monocrystalline Si-cantilevers in both conventional MOCVD and ETEM-MOCVD systems. The conventional MOCVD provided a framework for initial parameter tuning, while ETEM-MOCVD offered valuable insights into early nucleation and catalyst-substrate interactions. Our findings show that nucleation is significantly influenced by the removal of native oxide layers and the initial formation of the Au-Si alloy. Ourin situstudies revealed different NW-substrate interfaces, essential for optimizing the epitaxial growth process. We identified three typical configurations of NW 'roots', each impacted by growth conditions and preparation steps, affecting the structural and potentially the optical properties of the NWs. Similarly, doping from the Si-substrate may affect both optical and electrical properties; however, compositional analysis revealed no traces of Si in NWs post-nucleation and a small amount in the catalytic droplet. Our research highlights the importance ofin situstudies for a comprehensive understanding of nucleation mechanisms, paving the way for optimizing III-V NW growth on Si substrates and developing high-performance III-V/Si devices.

Dislocation-Driven Formation of Oriented Macroperiodic Metastructures of Curved Single Crystal Lattices in Glass.

Single crystals fabricated in glass by localized heating can develop uniquely deformed lattices stabilized by the surrounding amorphous medium. The development of lattice curvature appears to be intrinsic to the crystal growth process in some systems, while the result of the locally changing crystallography in others. In this work, a model laser-fabricated rotating lattice Sb2S3 crystal grown in stoichiometric glass is used to demonstrate fabrication of novel macroperiodic metastructures that utilize intrinsic lattice curvature superimposed with subtle crystallographic influences. The limited availability of slip systems drives the lattice curvature magnitude to vary with crystal growth direction, maximizing for lattices aligned with the predominant Burgers vector along with corresponding increases in dislocation density. Misaligned lattice orientations form smaller secondary lattice curvatures arising from misaligned Burgers vectors with further elastic contributions. Over extended crystal growth, these secondary components align the lattice to rotate about either the <001> or <010> crystal axes forming repeating metastructures of lattice orientation with periodicity 20-160 microns in length. The mechanistic approach used in this work may be expanded to other systems with known slip systems to better understand and design macroperiodic metastructures.

Transmission Line Icing Prediction Based on Physically Guided Fast-Slow Transformer

To improve the accuracy of the icing prediction model for overhead transmission lines, a physics-guided Fast-Slow Transformer icing prediction model for overhead transmission lines is proposed, which is based on the icing prediction model with meteorological input characteristics. First, the ice cover data is segmented into different time resolutions through Fourier transform; a transformer model based on Fourier transform is constructed to capture the local and global correlations of the ice cover data; then, according to the calculation model of the comprehensive load on the conductor and the conductor state equation, the variation law of ice thickness, temperature, wind speed, and tension is analyzed, and the model loss function is constructed according to the variation law to guide the training process of the model. Finally, the sample mixing enhancement algorithm is used to reduce the overfitting problem and improve the generalization performance of the prediction model. The results show that the proposed prediction model can consider the mechanical constraints in the ice growth process and accurately capture the dependence between ice cover and meteorology. Compared with traditional prediction models such as LSTM (Long Short-Term Memory) networks, its mean square error, mean absolute error, and mean absolute percentage error are reduced by 0.464–0.674, 0.41–0.53, and 8.87–11.5%, respectively, while the coefficient of determination (R2) is increased by 0.2–0.29.

Growth Pathway of CdS Nanoplatelets Investigated by In Situ X-ray Scattering and Optical Spectroscopy.

Two-dimensional (2D) CdS nanoplatelets (NPLs) have attracted much attention due to their sharp absorption peaks and unique optical properties, but their formation mechanism has not been clearly explained. In this study, the whole growth process of 2D CdS NPLs from the original precursor compounds to the final products was investigated by in situ small-angle X-ray scattering (SAXS), ultraviolet-visible (UV-vis), and transmission electron microscopy (TEM). It reveals that the growth of CdS NPLs can be divided into three stages, i.e. dissolution of the precursors Cd(OA)x(OAc)2-x and sulfur powder accompanied by the formation of CdS precursor compounds (PCs) from 30 to 120 °C (stage I), formation of the CdS magic-sized clusters (MSCs) and their growth into NPLs from 120 to 240 °C (stage II), and curling and uncurling growth of the NPLs at 240 °C (stage III). Dramatically, the shape of the NPLs changes from flat to curly when the temperature reaches 240 °C, but very interestingly, they become flat again after a prolonged stay at 240 °C. The curling and uncurling of NPLs is proposed to be driven by their surface stress imbalance induced by ligands.

Phase Field Simulation and Experimental Study of Carbide Precipitation Process in Submerged Arc Welding on Descaling Roll

The mechanical properties of surfacing layers are significantly affected by the precipitation and evolution of carbides in nickel-based alloys. At present, the study of carbide precipitation in a Ni-Cr-B-Si surfacing layer is described by using the phase field method. In this paper, the true Gibbs free energy of the M23C6 carbide phase in Ni-Cr-C ternary alloy was established by the CALPHAD method and thermodynamic database. The growth and coarsening process of M23C6 carbide was simulated based on phase field method. The microstructure of M23C6 carbide of Ni-Cr-C alloy at 1373 °C isothermal aging time was observed by scanning electron microscope (SEM). The results show that the growth and coarsening of the precipitated M23C6 carbide phase are undergone through multiple processes during isothermal aging. First, a single precipitate core is formed, and then the single precipitate continues to coarsen and grow, forming a lamellar structure. Two precipitates contact to form a single rod-like structure, and multiple precipitates form slender rod-like structures. Finally, the contacting elongated rod-like structures grow, forming a typical layered eutectic carbide. The precipitation behavior, growth, and coarsening process of M23C6-type carbides in Ni-Cr-B-Si series alloys are explored through phase field simulation and experimental research in this paper. A theoretical basis is provided for the rational control and distribution of carbides in surfacing layers. A reference is also offered for optimizing the nickel-based superalloy materials used for surfacing the surface of descaling rolls.

Creation of Segmented Platelets with Diverse Crystalline Cores Using Double Crystalline Triblock Copolymers.

Two-dimensional (2D) platelet structures with uniform dimensions and spatially defined diverse cores are highly sought but are still challenging to access. Living crystallization-driven self-assembly (CDSA)-seeded growth enables the creation of uniform 2D core-shell nanomaterials with diverse core compositions via sequential epitaxial crystallization of block copolymers. Nevertheless, general limitation of the growth process to strict requirements of heteroepitaxial crystallization is a major obstacle to the formation of segmented nanoparticles with extended diverse core chemistries. Herein, we introduce a strategy of using double-crystalline triblock copolymers, such as poly(ε-caprolactone)-block-poly(p-dioxanone)-block-poly(N,N-dimethyl acrylamide) (PCL-b-PPDO-b-PDMA), as bridges to create segmented platelets with compositionally distinct cores. The epitaxial crystallization of the PCL block excludes the PPDO block, forming out-of-plane PPDO crystals that seed subsequent epitaxial crystallization of the added PPDO unimer, producing flat-on quasi-square PPDO crystals. Meanwhile, the less-defined orientation of PPDO crystals has confirmed the presence of flat-on epitaxy between PCL and PPDO. For comparison, PCL-b-PHL (PHL = poly(ζ-heptalactone)) forms in-plane crystals with a strictly defined orientation via edge-on epitaxy due to the cocrystallization of PCL and PHL. Therefore, this approach provides a novel route to construct precisely controlled segmented 2D platelet structures with chemically distinct cores and tunable functionalities, an extension to expand the precise design of complex nanoparticles.

Medium entropy-derived flower-like FeCeCu nanozyme with excellent oxidase-like activity for on-site and visual detection of carbosulfan.

Carbosulfan residues in environment is very harmful to human health. The rapid and high sensitive detection of carbosulfan residues is particularly important to guarantee human health and safety. The conventional chromatographic techniques and enzyme inhibition strategies cannot realize on-site and visual detection of carbosulfan. It is clear that a novel nanozyme-based method was need, which exhibited advantages in low-cost, rapidity, and portability with easy-to-use operation. A medium entropy-derived flower-like FeCeCu nanozyme (FeCeCuzyme) were prepared via the metal-organic coordination method with "Ostwal ripening" growth process. FeCeCuzyme exhibited an excellent oxidase-like activity due to an abundant active sites in the flower-like structure. Carbosulfan can produce the sulfide compound by hydrolysis reaction under acidic condition, which could easily form sulfide-metal bonds with FeCeCuzyme, thereby significantly quenching their oxidase-like activity and hindering nanozyme-mediated chromogenic reaction. Given this phenomenon, the FeCeCuzyme were used as a colourimetric sensor for highly-specific carbosulfan detection without using acetylcholinesterase and H2O2. The FeCeCuzyme colourimetric sensor showed a wide linear range from 0.15 to 50.00μM (R2=0.9970) with low detection limit of 0.13μM. Meanwhile, FeCeCuzyme sensor was integrated with smartphone to design a portable detection platform, which realizes the on-site and rapid detection of carbosulfan with easy-to-operation. A low detection limit of 0.14μM was obtained in the linear relation of 0.15-50.00μM. The satisfactory recoveries (91.17%-108.00%) from the spiking method were highly agreed with HPLC technique, and which further verified the feasibility of FeCeCuzyme-based strategies in real samples. This work provides a pioneer new avenue for design of novel nanozymes, and offers an efficient alternative to the conventional methods for specifical, fast, and on-sites detection of carbosulfan in environment.