Lateral Growth Rate Research Articles

Growth Rate in Cultured Crustose Coralline Algae of the Genus Phymatolithon and Sporolithon From Taiwan

ABSTRACTCoastal algal reef ecosystems, which are formed by the skeletal carbonate of crustose coralline algae (CCA), provide vital habitats for a diverse range of marine organisms and serve as valuable archives of long‐term environmental data. Despite the importance of these reef ecosystems, there is currently a lack of available information regarding the accretion rates of CCA in subtropical intertidal zones in the Taoyuan algal reef. We measured the vertical accretion and horizontal growth of CCA cultured in two aquaculture tanks over a 9‐month period. The vertical accretion and horizontal growth rate of CCA was approximately 0.29–0.43 and 5.5 μm·day−1 (the extrapolated annual value is equivalent to 0.11–0.16 and 2.0 mm·year−1, respectively). Newly colonized CCA had faster horizontal growth of approximately 110 μm·day−1 (equivalent to 40.2 mm·year−1). These results highlight the slow and gradual process of algal reef ecosystem formation in the subtropical intertidal zones. The CCA had a faster lateral growth rate as seen in the newly settled CCA. These findings contribute to our understanding of the overall growth dynamics of CCA.

Controllable growth of large 1T-NbTe2 nanosheets on mica by chemical vapor deposition and its magnetic properties

Two-dimensional (2D) magnetic materials have recently attracted broad attention for their potential technological applications. Here, we report controllable growth of NbTe2 nanosheets on mica substrate by atmospheric chemical vapor deposition. Different from the SiO2/Si substrates, dangling bonds on the surface of the mica are absent, which induces low nucleation density and higher lateral growth rate. As a result, the lateral size of NbTe2 nanosheets on mica substrates can be significantly larger than those on SiO2/Si substrates. Large single crystal NbTe2 nanosheets with a lateral size of up to 151 µm were fabricated on a mica. High-resolution transmission electron microscope image, XRD patterns and Raman spectra reveal the NbTe2 nanosheets adopt the single crystal with 1T phase. Furthermore, the NbTe2 nanosheets on mica demonstrate ferromagnetic properties with a Curie temperature of up to 162 K. Our work paves the way for the atmospheric chemical vapor deposition growth and applications of many more 2D magnets.

Revealing the kinetic behaviors of hydrate formation on bubble surface with different pressure gradients in deep-sea methane seepage areas of the South China Sea

In the deep-sea methane seepage environment, hydrate formation on the methane bubbles is a crucial pathway for methane transformation, and plays an important role in determining whether seepage methane can enter the surface ocean. While how the pressure determines the hydrate formation process in different water depths remains unclear. In this study, we investigated the formation kinetic characteristics and microstructure evolution of methane hydrate on suspended gas bubbles within varied pressure conditions. The pressure range (4–14 MPa) was in the deep-sea methane seepage environment. The results indicated that pressure obviously affected the hydrate film formation characteristics. As pressure increased, the lateral growth rate of the hydrate film accelerated, the hydrate crystal particles became smaller, and the initial hydrate film surface became smoother. Raman spectroscopy results showed that pressure changes did not obviously alter the microporous evolution on the hydrate film surface, that the gas-phase/water-phase Raman peak area ratio exhibited similar trends. The dissolved methane concentration under different pressure conditions was not the primary factor affecting hydrate thickening, rather, it depended mainly on the driving force. This study is of great significance in revealing the characteristics of methane hydrate formation and methane transfer in the oceanic methane seepage environment.

The morphology of liquid CO2 hydrate films at different temperatures under saturation pressure

CO2 hydrate film formed on the surface of water droplets in liquid CO2 was studied via digital microscope system and in situ Raman spectrometer. Temperature significantly affects the initial morphology and lateral growth rate of hydrate film. In the temperature range of 273.15–279.15 K under corresponding saturation pressure of liquid CO2, the growth and development process is primarily separated into three stages, that is, rapid lateral growth, rapid thickening, and slow development. However, in the temperature range of 280.15–282.15 K, the growth and evolution of hydrated film is dominated by rapid lateral growth and slow development processes, while the rapid thickening disappears on our experimental scale, caused by the decrease in the driving force. Each of these two temperature ranges has unique characteristics and interesting discoveries during the hydrate film formation and development. For hydrate film formed at 283.15 K, the formation of hydrate is very difficult. It needs to nucleate inside the droplet with the assistance of the hydrate crystal seeds remaining in the water droplet after decomposition, so that the small hydrate crystals can grow in the water phase, and as the crystals get larger, they will eventually emerge on the droplet’s surface and produce a complete hydrate film. Combining the experimental phenomena during the growth and development of hydrate films at various temperatures, the further growth of the hydrate phase during the generation process mainly depends on the mass transfer process of water molecules through the hydrate film. This work provides valuable information on the mechanism of nucleation, growth and decomposition of liquid CO2 hydrate crystals, which is of great significance for applications in seafloor CO2 gas sequestration.

Investigation on methane hydrate formation behaviors in deep-sea methane seepage environments

Deep-sea cold seep is a natural phenomenon where methane leaks from the sea floor. Methane can be partially conversed through physical, chemical, and biological processes, but the excess methane that remains uncaptured escapes into the atmosphere and contributes to the greenhouse effect. Physical carbon sequestration via hydrate formation is a fast and high-energy density type of carbon sequestration; however, it has been largely overlooked. This study investigated hydrate formation in authigenic carbonate rocks through deep-sea geological surveys in cold seeps in the South China Sea. Investigations have shown that authigenic carbonate rocks can sequester carbon by blocking the methane plume from the seepage vents. This perspective provides a new physical carbon sequestration mode of carbonate rocks by observing the artificial collection of methane plumes in deep-sea seepage areas. The mode was simplified into two steps including the formation of a thin layer of planar hydrate film on carbonate rocks and a thick layer of hydrate through the stacking of bubbles under the thin film. Salinity, a key distinction between seawater and freshwater, was further investigated for its impact on the carbon sequestration mechanism. Results showed that saline ions in seawater had little impact on the thickening rate of the planar hydrate film but reduced the lateral growth rate of hydrates on the bubble by 60%. This reduction in the lateral growth rate greatly facilitated the three-dimensional growth, increased the hydrate thickness on the bubble, and improved the carbon sequestration efficiency. Hydrate formation on the exposed carbonate rock can effectively impede methane plume migration into upper water and atmosphere, mitigate the greenhouse effect, and present a promising strategy for carbon sequestration in deep-sea methane seepage areas.

Stress evolution of fault-and-thrust belts in 2D numerical mechanical models

We employed numerical models to examine the dynamics of fold-and-thrust belts (FTBs), particularly focusing on the spatial and temporal interplay between stress variations and fault development. Our study explores the effects of variables such as layer thickness, basal friction, and surface diffusivity on the FTBs’ structural development, emphasizing the conditions under which frontal thrusts form. We found that fault activities within FTBs exhibit a cyclic behavior characterized by phases of initiation, quiescence, and reactivation. For over 95% of the total cycle duration, the frontal thrusts are the only active structures, and the stress within the FTB predominantly remains in a critical state. During the remaining 5%, the stress becomes over-critical, leading to the formation of a proto-thrust zone and the reactivation of pre-existing thrusts within the FTB. The lateral growth rate of FTBs is directly related to the thickness of the deforming layer, with the progression of the deformation front maintaining a steady pace across the study period. Additionally, our analysis on the progression of FTBs highlights the critical role of zonal failure spacing in determining the structural styles within FTBs. Our results indicate that narrowly spaced zonal failures, which promote the emergence of low-angle forethrusts, are more likely to occur at increased distances from the backstop. This explains the sequential frontal failure in the FTB; however, the stress accumulating at the rear weak zones also play an important role in the evolutionary patterns of the FTB. Our study offers new insights into the complex processes governing the mountain formation.

Promotion mechanism of carbon dioxide hydrate formation by l-Methionine and its competitive effects with NaCl

The growth kinetics and macroscopic morphology evolution of CO2 hydrate promoted by l-Methionine (L-Met) in NaCl aqueous solutions in a wide range of mass fractions were systematically investigated. 0.05 wt% was the threshold mass fraction of L-Met to have prominent promotion effects in a batch mode. The addition of NaCl could suppress its promotion performance, while it could be regained by further addition of L-Met to 1.0 wt%. Porous feature and wall-climbing phenomena of CO2 hydrate were obvious in the presence of L-Met while it could be suppressed by NaCl. The tangential (lateral) growth rate of the hydrate film on planar pure water surface was the highest while both L-Met and NaCl could decrease it. For L-Met, it was the highest at 0.05 wt%. Special ball-like, mosaic-like and sword-like appearances of CO2 hydrates were found. Both the adsorption-capillary effects of L-Met and the hydration effects of L-Met and NaCl were thought to account for all the phenomena and a detailed scenario was proposed and discussed. A macroscopic growth model based on the tangential growth rates of hydrate films was proposed and evaluated.

Nucleation and grain growth in low-temperature rapid solid-phase crystallization of hydrogen-doped indium oxide

Nucleation and grain growth are discussed as a means of clarifying the mechanism of the rapid solid-phase crystallization (SPC) process of H2-doped amorphous indium oxide (InO x :H) films. H2-doping in InO x :H films reduced nucleation density at 250 °C from 4.1 to 1.1 μm−2, resulting in an increase in grain size and Hall mobility of the polycrystalline (poly)-InO x :H films. Lateral growth rate from the nucleus was estimated to be 220 nm min−1 for the InO x :H film at 250 °C. Thus, an amorphous InO x :H film could be converted to a poly-InO x :H film within 3 min owing to a fast lateral growth rate from the nucleus. Almost the same grain size, Hall mobility, and carrier density could be obtained from the poly-InO x :H films after annealing at 250 °C for only 3 min irrespective of the ramp rate. The results demonstrated the wide range of the processing window for SPC for poly-InO x :H films.

Effect of asphaltenes on growth behavior of methane hydrate film at the oil-water interface

Investigation of the effect of asphaltenes, the natural surfactant in crude oil, on the methane hydrate formation is crucial for flow assurance in deep-water oil and gas field. However, most of recent studies on hydrate growth mainly focused on the impact of artificial and commercial surfactants. Limited attention has been given to the effect of the important natural surfactants presented in crude oil on hydrate film growth, such as asphaltenes. In this study, the influences of dissolved asphaltenes on the properties of oil-water interface and the growth of methane hydrate film were investigated. The morphology of methane hydrate film on the water droplet in the oil phase with different asphaltene concentrations was in-situ visualized in a visual autoclave equipped with microscopic imaging, and the lateral growth rate of the methane hydrate film was measured. The results showed that the addition of asphaltenes could increase the hydrophobicity of the methane hydrate film, inhibit the growth of hydrate, and change the morphology of the hydrate film. The growth rate of the hydrate film was negatively correlated with the asphaltene concentration (0–200 ppm), but stabilized above 200 ppm. In addition, this inhibition effect on the lateral growth rate was negatively correlated with temperature.

Investigating the Fundamental Conditions for Quantitative Growth to Obtain High-Quality WS2 Using a Process of Physical Vapor Deposition

Two-dimensional layered transition-metal dichalcogenides (2D-TMDs) have garnered significant attention due to their layer number-dependent electronic properties, making them promising candidates for atomically thin electronics and optoelectronics. However, current research has primarily focused on exfoliated TMD materials, which have limitations in size, layer number control, and yield. Therefore, a crucial challenge remains in producing large single TMD crystals with precise control over the layer number. A comprehensive understanding and precise control of the growth conditions are imperative to address this challenge. This study systematically investigated key growth conditions, including temperature, precursor flow, growth duration, material quantity, gas flow, and slide position. By optimizing these parameters, we successfully synthesized TMD materials with an impressive size of 850 µm. Notably, we achieved the preparation of monolayer WS2 single crystals on a large scale within a remarkably short duration of 10 min, exhibiting a lateral growth rate of up to 1.4 μm/s, which is comparable to the best-exfoliated monolayers. The findings from our study provide a robust pathway for the rapid growth of high-quality TMD single crystals, facilitating further advancements in this field.

Regime transition temperature of poly(ethylene oxide) in thin films: Effect of film thickness and molecular weight

In thin films of poly(ethylene oxide), the regime transition temperature between regimes II and III, TIII→II, was found to increase with decrease in the film thickness D below 1 μm and increase in the molecular weight (Mw). When D was 1 μm or greater, TIII→II was found to be highly dependent on Mw and independent of D. As D decreased, the dependence of TIII→II on Mw decreased. The spherulitic growth rate, on the other hand, was almost independent of D for D ≥ 100 nm. These results were discussed based on the suppression of chain mobility in the cases of small D and high Mw. The reduced mobility slowed down the lateral growth rate of secondary nuclei and relatively enhanced the secondary nucleation frequency. The results also implied that the surface free energy of the folded surface decreases with lowering D and that the chain folds are disordered.

Selective-area growth of GaN and AlGaN nanowires on N-polar GaN templates with 4° miscut by plasma-assisted molecular beam epitaxy

In this study, selective area growth (SAG)s of AlGaN/GaN nanowires (NWs) on miscut N-polar GaN templates were studied and compared with that grown on Ga-polar templates using plasma-assisted molecular beam epitaxy (MBE). The SAG of N-polar AlGaN/GaN NWs demonstrated higher growth rate and more growth selectivity than that of Ga-polar AlGaN/GaN NWs. Additionally, lateral growth rate of N-polar NWs was significantly lower than Ga-polar NWs. Compared to the pyramidal shaped top surfaces of Ga-polar NWs, the N-polar GaN NWs had flat head top surfaces. The combination of higher growth selectivity, larger growth window, negligible lateral growth, and flat head, makes N-polar (Al,Ga)N NWs attractive for a variety of applications including UV LEDs and detectors as well as quantum sensing.

The effects of self-assembling off-angles on the homoepitaxial lateral outward growth of single-crystal diamond

The surface morphology formed at the initial growth stage is crucial for the homoepitaxial growth of large-area single-crystal diamond (SCD). In this paper, the self-assembly of off-angles on diamond (001) crystal face and the evolution of surface morphology during the epitaxial lateral outward growth of SCD by microwave plasma chemical vapor deposition (MPCVD) have been intensively investigated. At the beginning of the growth, inwardly inclined off-angles formed at the corners of the top surface of SCD sample, which may lead to the formation of secondary nucleation and polycrystalline diamond (PCD) at the edge regions. In comparison, the size of the SCD plate after repeated homoepitaxial lateral growth could be expanded from 3 × 3 mm2 to 4.9 × 4.9 mm2 by self-assembling an outwardly inclined off-angle on diamond (001) crystal face at initial growth stage. The SCD without PCD rim could be obtained in both enclosed holder and semi-open type holder by self-constructing an outwardly inclined off-angle on the growth surface. The lateral growth rate of SCD in the semi-open holder was increased by 2.3 times compared with that in the enclosed holder. Additionally, the lateral surface of SCD grown in a semi-open holder shows a typical step-flow growth pattern.

An application of mixed-effects model to evaluate the role of age and size on radial variation in wood specific gravity in teak (Tectona grandis)

To test whether radial variation of wood specific gravity (WSG) is controlled by tree age or tree size in teak (Tectona grandis L.f) plantation trees, opposing different-length pith-to-bark strips which represents the differential lateral growth rate was compared using mixed-effects model which considers the heterogeneity of variances and dependency in the data to gain insight into the stochastic processes that govern the wood formation process. Various models were tested in devising an appropriate radial WSG model. Models that accounted for serial correlation in WSG data performed better than the simple structure that assumes zero correlation between measurements. The autoregressive plus random tree effect structure performed better in describing the radial variation pattern. The variability of the data related to random fluctuations during tree development and the wood formation process is modeled by the autoregressive parameter revealing the intrinsic complexity of wood formation. Since they cannot be attributed to observed factors, models should consider temporal or serial correlations when assessing wood quality. The results revealed that tree age is a decisive factor in controlling the WSG of wood, while tree size is statistically less important. Furthermore, the core wood production period varies with the growth rate. It is shown that the core wood area decreased with slow growth. Findings presented here appear to provide the first demonstration of radial variation in WSG with respect to growth rate and age for planted teak growing in Ghana.

Investigating cyclopentane hydrate nucleation and growth using microfluidics

The success of geological storage of carbon dioxide (CO2) in depleted oil and gas reservoirs relies among other aspects on the efficiency of CO2 injection, especially in the near-wellbore area where flow rates are high. CO2 hydrates pressure/temperature equilibrium conditions may be reached in this zone due to cooling associated with the Joule–Thomson effect; such CO2 hydrate formation may lead to strong injectivity loss and impair drastically the onsite well operations. In this study, cyclopentane hydrates (CPH) were employed as CO2 hydrate proxy (i.e. formation at atmospheric pressure) to mimic CO2 hydrate formation at higher pressure. In this study, the nucleation and growth processes were determined using a droplet-based in-house-microfluidic device. The generation of water droplets in cyclopentane liquid using the co-flow method was achieved. Trains of identical water droplets were stored in a serpentine channel. Each isolated droplet in this channel serves as a separate reactor. The temperature was controlled using a Peltier module to initiate hydrate nucleation at low temperatures. The isolated droplets provided the opportunity to statistically analyze the kinetic behaviors by varying key parameters, such as thermal history and water salinity. Detection of the onset of crystallization in water droplets over time and temperature allowed us to plot conversion curves based on imposed parameters. The effect of thermal history and dissociation temperature was first compared using pure water. This study marks the initial investigation into how NaCl influences CPH formation in microfluidic devices, focusing on isolated water droplets within serpentine tubes. The progression of ice nucleation, ice melting, the onset of CPH crystallization, CPH growth, and CPH dissociation are illustrated in water droplets exposed to changing temperatures. The addition of NaCl in the water during the procedure exhibited a noteworthy impact on CPH formations. With the same temperature profile, salt concentration delays nucleation (thermodynamic effect) and slows down growth. Our findings suggest that higher subcooling accelerates nucleation and growth rates. Initial lateral growth rates ranged from 4.22 μm/s to 2.14 μm/s, with a subcooling of 4.2 °C observed between 2 and 7 min for a pure water droplet.

Facet Control and Material Redistribution in GaN Growth on Three-Dimensional Structures

In this work, the influence of temperature and ammonia partial pressure on the GaN shell morphology grown on GaN microfin cores is investigated. We demonstrate that GaN overgrowth on 3D structures above a temperature of 1000 °C is determined by the competition between growth and decomposition that results in the redistribution of material between coexisting surfaces due to their different thermal stabilities. By studying the GaN shell growth under different reactor parameters, we show that decomposition processes, often disregarded during planar growth, strongly influence the vertical-to-lateral distribution of material during GaN growth on 3D structures. We observed that GaN shell growth on a-plane microfins at high temperatures and high ammonia fluxes results in an increase of the decomposition rate of the c-plane surfaces and thus, reduces the growth rate in the vertical direction. On the contrary, the lateral growth rate increases due to the diffusion of material from the less stable c-plane facet to the more stable a-plane facet where it reincorporates. Furthermore, under certain growth conditions, the decomposition of the c-plane outweighed the incorporation, reducing the height of the initial 3D structure during growth, while still gradually growing in the lateral direction, which resulted in the development of inclined facets. These findings highlight the high sensitivity of 3D structures to thermal decomposition processes and redistribution of material. Therefore, the understanding of these mechanisms and their interaction is required for controlling and optimizing growth on these architectures.

Reef Complexes of the Late Ordovician–Early Silurian Altai Basin: Classification, Structure, Paleobiota, and Paleogeography

Abstract —The paper presents data on the classification, structure, and biota of reef complexes from the Late Ordovician–early Silurian Altai Basin. The early Paleozoic history of the Altai Basin included the early–middle Katian, late Katian, early Hirnantian, late Telychian, and middle–late Sheinwoodian events of large-scale reef formation which produced framework reefs, mud mounds, and coral meadows. The early Paleozoic reefs of the area formed at rates of 40 to ~12 cm per thousand years. The late Telychian reef system, which formed in 0.51–1.0 Myr, occupied the largest area of the basin. The lateral extent of reef systems in the Late Ordovician–early Silurian basin of Altai depended more on the rates of vertical and lateral growth, as well as on the previous sea bottom topography and clastic inputs, than on the duration of reef formation. Carbonate deposition in the Altai basins of that time can be simulated with a general model implying formation of distal barrier reefs.

Film formation kinetics of Methane-propane hydrate on gas bubble in MEG and luvicap EG solutions

Hydrate plugging in deep sea oil & gas transportation is the final result of morphological evolution of hydrate growth. However, effect of hydrate morphological evolution in the presence of hydrate inhibitors with respect to flow assurance is rarely studied. In this work, methane-propane hydrate forming system by suspending gas bubbles in pressurized aqueous phase was studied to evaluate the hydrate film growth kinetics in the presence of thermal and kinetic inhibitors (MEG, LuviCap EG) at subcooling levels of 10–15 K. Along with morphological observations with optical microscope, the results suggested that: (1) KHI showed better inhibition performance on hydrate growth with hydrate film as a barrier for mass transfer; (2) 4000 ppm performed as a threshold concentration of hydrate film formation on bubble; (3) crater structures, as potential mass transfer channels, are the morphological characteristics of KHIs adsorbing to the hydrate film. In addition, the effects of environmental factors on the growth kinetics of hydrate on bubble showed that the subcooling determined the lateral growth rate of hydrate film, the inhibitor concentration determined whether a film was formed, and the craters structure on the hydrate film determined the mass transfer in the initial thickening stage of hydrate film growth. The research could shed new light on fine-tuning of the inhibitor concentration and level of subcooling to effectively inhibit the growth of hydrate in gas pipelines and assure the multiphase flow in deep sea oil & gas transportation.

Surface protrusion induced by inter-diffusion on Cu-Sn micro-pillars

With downward scaling of the micro-bumps in three-dimensional integrated circuits, surface inter-diffusion becomes dominant, changing the kinetic path of intermetallic compounds (IMC) formation and causing serious reliability issues. However, an in-depth understanding of the surface inter-diffusion process and the corresponding influence on the formation mechanism of IMC in a micro-bump remain unclear. We conducted annealing at 170 ℃, over 16 h for pillar type Sn/Cu micro-bumps and observed a unique 2-step sidewall Cu3Sn IMC formation phenomenon on the FIB-cut clean surface of the micro-bumps. It is found the two-step sidewall IMC formation is dominated by the surface inter-diffusion of Sn and Cu atoms. Density functional theory calculations reveal that the activation energy barrier of nucleation for sidewall Cu3Sn IMC is about 1/3 of that of sidewall Cu6Sn5 on corresponding interfacial IMC layers, making the formation of sidewall Cu3Sn dominant. Moreover, we proposed a kinetic model that can predict the mean lateral growth rate of the sidewall IMC which may cause fatal short-circuit failure.

Reactive pulsed laser deposition of low particulate density and epitaxial TiN films on Si (100) for functional oxide integration

• Low particulate density epitaxial TiN on Si (100) is deposited via reactive PLD. • Plume chemistry (N/Ti) alters the structure and microstructure of the TiN film. • TiN films roughen in RPLD process under low N availability. • Edge mobility along ><˃˄110> TiN limits the lateral growth rates. • Ferroelectric BaTiO 3 is epitaxially integrated on reactive PLD TiN/Si. Epitaxial TiN films on (100) Si have been realized by reactive pulsed laser deposition (PLD). Their utility is demonstrated by subsequent growth of epitaxial BaTiO 3 . PLD geometry optimization has yielded TiN films with a low particulate density, ∼ 6 × 10 3 cm −2 , but with a growth rate, ∼1 μm/hr, comparable to the standard On-axis geometry. The method of heat up to growth temperatures yields oxide free epitaxial interface, (001) TiN ||(001) Si and <100> TiN ||<100> Si and ω-scan full width at half maximum of 1.2° in symmetric and asymmetric geometries. Repetition rate and fluence effect studies have resulted in films with a surface roughness of < 5 nm as required for device fabrication. Parameters that increase surface roughness also raise oxygen incorporation. A BaTiO 3 -TiN-Si stack, (001) BaTiO3 ||(001) TiN ||(001) Si and <100> BaTiO3 ||<100> TiN ||<100> Si , is demonstrated with switchable out of plane polarization.