Surface Structure Research Articles

Pore Structure and Fractal Analysis of Low-Resistivity Longmaxi Shale in the Southern Sichuan Basin Combining SEM, Gas Adsorption, and NMR.

Pore structure can affect the reservoir property, petrophysics, and fluid migration/adsorption, which is critical for shale evaluation and development. In this paper, the pore structure, fractal characteristics, and their influencing factors on low-resistivity shale (LRS) from the Longmaxi Formation in the Southern Sichuan Basin were analyzed by combining geochemistry experiments, physical property analysis, X-ray diffraction, scanning electron microscopy (SEM), N2/CO2 gas adsorption experiments, and nuclear magnetic resonance (NMR). The results indicate that in LRS, the layered clay mineral/pyrite distribution and more developed pores with a larger size and better connectivity can build a complex and superior conductive network. In gas adsorption tests, the pore volume (PV) is primarily contributed by mesopores in sizes of 2-4, 10-30, and 40-50 nm; the specific surface area (SSA) is mainly controlled by mesopores of 2-4 nm and micropores of 0.5-0.7 nm. The pore structures characterized by NMR, gas adsorption experiments, and SEM are consistent. In addition, gas adsorption is more suitable than NMR for describing the fractal dimension, where the development of micropores enhances the heterogeneity and complexity of the pore surface and pore structure. The gas-producing LRS has larger D1 and D2 than water-producing LRS. Moreover, TOC contributes to the development of micropores to some degree. Quartz and illite are negatively correlated with the PV and SSA of mesopores and total pores, while pyrite, clay mineral, and illite/smectite (I/S) are converse with a positive relationship. There exists only one negative relationship between chlorite and D2, and chlorite is weakly positively correlated with the large pore volume and negatively correlated with the micropore SSA.

Calcium regulates the physiological and molecular responses of Morus alba roots to cadmium stress

Heavy metal cadmium (Cd) is toxic to organisms. Mulberry (Morus alba L.) is a fast-growing perennial that is also an economical Cd phytoremediation material with large biomass. However, the molecular mechanisms underlying its Cd tolerance remain unclear. Here, we reveal the physiological and molecular mechanisms underlying Cd toxicity under varying calcium (Ca) treatments. First, under low-Ca treatment (0.1 mM Ca), mulberry growth was severely inhibited and the root surface structure was damaged by Cd stress. Second, electrophysiological data demonstrated that 0.1 mM Ca induced an increased Cd2+ influx, leading to its accumulation in the entire root and root cell walls. Third, high-Ca treatment (10 mM Ca) largely alleviated growth inhibition, activated antioxidant enzymes, increased Ca content, decreased Cd2+ flux, and inhibited Cd uptake by roots. Finally, 0.1 mM Ca resulted in the activation of metal transporters and the disruption of Ca signaling-related gene expression, which facilitated Cd accumulation in the roots, aggravating oxidative stress. These adverse effects were reversed by treatment with 10 mM Ca. This study preliminarily revealed the mechanism by which varying Ca levels regulate Cd uptake and accumulation in mulberry roots, provided an insight into the interrelationships between Ca and Cd in the ecological and economic tree mulberry and offered a theoretical basis for Ca application in managing Cd pollution.

Step-by-step silicon carbide graphitisation process study in terms of time and temperature parameters

This work investigates the temperature and time as key parameters for graphene formation on the silicon carbide surface during the high thermal decomposition process. Measurements were performed using various experimental techniques under ultra-high vacuum conditions. The graphitisation process was divided into various stages, after which the surface chemical composition and atomic structures were analysed in detail. It has been shown that despite the known theory of graphitisation mechanism and initial condition for occurrence of this process, the application of different temperatures and heating times affect the quality and quantity of formed graphene layers. Applying a temperature too low or annealing the sample for a too short time led to an inefficient silicon sublimation process. On the other hand, too high temperature during flashing modifies the visibility of surface structures, which may be crucial for other investigations and potential applications of such systems.

Water-induced surface ordering facilitating the microcutting of ductile metals

Metal cutting is a crucial process in modern manufacturing. Enhancing the machinability of metals can significantly improve their production efficiency and surface integrity. Coating surface-active media (SAM) on the free surface of the metals before cutting is an easy method to improve machinability, which usually pertains to the category of the renowned Rehbinder effect. However, the existing SAM is usually hazardous and complex materials. Besides, the effect of SAM on the local structure of the metal surface remains unclear. In this study, water is employed as a simple yet often overlooked SAM in the microcutting of copper. Using water as SAM also allows the employment of X-ray absorption fine structure spectroscopy (XAFS) to study the local structure of copper with and without water coating. Results show that water coating on the free surface of copper can significantly reduce the cutting force and chip thickness, and improve the surface finish. Interestingly, removing the water coating enables the recovery of the cutting force, demonstrating a reversible effect. Based on the XAFS results and molecular dynamics simulation, a water-induced surface ordering mechanism is proposed to explain the findings from the microcutting experiments. This mechanism suggests that water molecules can induce surface ordering in copper, resulting in reduced surface energy and fracture toughness of copper, thus enhancing machinability. This work provides valuable insights into the comprehension of the Rehbinder effect and shows that picometer-scale modifications of the surface atom arrangement can considerably alter the deformation mode of metals, paving the way for the development of new manufacturing processes.

Tailoring electrochemical CO2 reduction selectivity over CuSn by modulating surface oxidation state with infrared laser treatment

Infrared laser treatment was used to precisely modify the surface structure of CuSn electrodes, effectively fine-tuning the selectivity of reduction products. With increasing laser power, the metallic Cu and Sn surfaces became more oxidized, and the Sn/Cu composition ratio varied with depth and further changed post-EC reaction. The diversity of reduction products, including C1 (CO, CH4, and formate), C2 (C2H4, ethanol, acetate, acetaldehyde, and glycolaldehyde), and C3 (propanol and isopropanol) compounds, shifted towards a more selective production of C1 (CO and formate) products. These tailored behaviors are attributed to variations in interfacial electronic structures, oxidation states, composition ratios, and the interaction between CO2 and the density of states (Cu, O, and Sn) near the Fermi level. The laser treatment method enables precise tuning of electrode surfaces, modulation of reduction products, and enhancement of selectivity. Moreover, this technique presents a novel approach for electrode design in the field of CO2 reduction, offering new avenues for optimizing catalytic performance.

Compressive Mechanical Properties and Energy Absorption of Cubic Spherical Hollow Cellular Material Based on the Rod and Curved Surface Structure

Cellular materials, such as lattices and honeycombs, were widely used for structural protection owing to their excellent mechanical properties. By combining the excellent characteristics of lattice and honeycomb curved surface structures, this study designed a cell called Cubic Spherical Hollow (CSH), which had the advantages of orthogonal isotropy and better spatial connectivity. Inspired by the micro-structural arrangement of bamboo fiber and conch shell, we designed the new CSH cellular materials through the interlayer offset strategy. Then, the effects of interlayer offset on the mechanical properties and compression deformation behavior were explored experimentally and simulatively. Compared with other cellular materials, CSH cellular materials exhibited excellent mechanical properties with higher specific strength and specific modulus. The arrangement offsets of the CSH cells between different layers led to a change in the deformation mechanism from a rod’s compressive mode to a combination of a rod’s compressive mode and curved surface’s bending mode. The initial peak stress and plateau stress decreased with the increased arrangement offsets of the CSH since the extruded protrusions of the structure filled the holes and reduced the lateral expansion behavior of the material in the pressurized environment. This phenomenon also reduced the transverse expansion and prevented the sudden change in stress in the constrained space, indicating that the structural deformation was stable and had excellent cushioning and energy absorption properties. In this study, the cellular material design strategy opens a new avenue for energy absorption.

Effect of ultrasound-assisted Maillard reaction on functional properties and flavor characteristics of Oyster protein enzymatic hydrolysates

To address the delamination phenomenon during storage and flavor characteristics of Oyster protein hydrolysates (OPH). In this study, xylo-oligosaccharides (XOS) were selected to covalently graft with OPH through ultrasound-assisted Maillard reaction, and the effect of ultrasound-assisted Maillard reaction on the structure, functional properties, and flavor characteristics of OPH were investigated. The results revealed that the ultrasound treatment led to a 1.46-fold increase in the degree of grafting compared with the conventional wet-heat Maillard reaction methods. Structural analyses at various levels indicated substantial alterations in the OPH structure following the ultrasound-assisted Maillard reaction. More ordered α-helical secondary structures were shifting to random coiling, the tertiary structure showed more stretching changes, and the surface structure was characterized by loose and porous features. Compared with OPH, the solubility of the ultrasound-assisted Maillard reaction products (OPH-U-M) increased from 54.67% to 70.14%, leading to a notable enhancement in storage stability. Flavor profile analysis demonstrated a decrease in unsaturated aldehydes and ketones presenting fishy and bitter aromas, while an increase in presenting meat aroma compounds was observed in OPH-U-M. Furthermore, OPH-U-M exhibited superior antioxidant properties with DPPH and ABTS radical scavenging abilities enhancing 46.05% and 42.09% in comparison with OPH, respectively. The results demonstrated that covalently binding with XOS under ultrasonication pretreatment endowed OPH with superior functional properties (including solubility, storage stability, and antioxidant activity), and the improvement of flavor profile. This study can provide theoretical guidance and practical implications for promoting the processing applications of oyster protein.

Optimizing Surface Texture Through Ion Induction for High Areal Capacitance and Enhanced Stability in MXene Electrodes

AbstractTo make supercapacitors a viable commercial product, it is necessary to increase the mass loading (ML) of the electrodes. However, current research on high ML MXene electrodes mainly focuses on internal structure optimization, often neglecting the importance of surface texture in the electrodes, which plays a crucial role in mediating interactions between the internal structure and the electrolyte. This study reports on a simple ion‐intercalation process that can reduce charge transfer resistance and improve cycling stability. Through the integration of 3D visualization models and wide‐angle X‐ray scattering techniques, a comprehensive investigation of the electrode's surface structure and MXene flake arrangement is conducted. The results showed that pre‐oriented aggregates induced by ion‐intercalation create a sophisticated surface structure with rich hills and valleys, promoting electrolyte permeation and ion exchange. This work highlights the significance of surface texture in films and electrodes, guiding the design of high‐performance materials.

Machine Learning Aided Design and Optimization of Antifouling Surfaces.

Antifouling surfaces, renowned for their strong surface resistance to proteins, cells, or tissues in various biological and environmental conditions, have broad applications in implanted devices, antibacterial coatings, biosensors, responsive materials, water treatment, and lab-on-a-chip. While extensive experimental research exists on antifouling surfaces, machine learning studies on this topic are relatively few. This perspective specifically focuses on exploring the complex relationships between the composition, structure, and properties of antifouling surfaces, examining how these factors correlate with surface hydration and protein adsorption. Different machine learning models have been developed to analyze and predict single and multiple protein adsorptions on various types of surfaces, ranging from structureless surfaces to well-ordered and rigid self-assembled monolayers, dynamically ordered polymer brushes, and complex filtration membranes. These models not only identify key descriptors or functional groups critical for antifouling performance (surface hydration, protein adsorption) but also predict the antifouling properties for a specific surface. Recognizing current challenges, this perspective delineates future research directions in the antifouling field. By leveraging and comparing current machine learning approaches, it aims to advance both the design and fundamental understanding of antifouling surfaces, thereby pushing the boundaries of innovation in this critical field.

Exploring the impact of Anions, Alkyl group and confinement effect in ionic liquid @ UiO-66(Zr) MOF: A DFT study

Metal organic frameworks (MOFs) have emerged as a strong research material due to their exceptional porosity and tunable functional nature. MOF structures consist of metal nodes with organic linker, which can be functionalized depending on the required application. With the tunable properties, it has wide range of applications in energy, environmental and therapeutic approaches. Nevertheless there are several factors which can affect their performance such as lower affinity towards target molecules, chemical and thermal stability etc. To counter these issues several studies have been devoted on functionalizing the MOF. In this work, we have considered UiO-66 (University of Oslo-66) MOF because of its exceptional thermal and chemical stability with a series of versatile ionic liquids (ILs). The selected ILs are 1-ethyl-3-methylimidazolium ([C2MIm]+) and 1‑butyl‑3-methylimidazolium ([C4MIm]+) cations with various anions [X]−, where X = acetate (OAc), tetrafluroborate (BF4), dicyanamide (DCA), nitrite (NO2) and chloride (Cl) anions. These ILs have been impregnated in tetrahedral (∼10 Å) and octahedral (∼16 Å) pores of UiO-66 structure. First principle density functional theory (DFT) approach is used to study the structure, stability, spectral properties and charge transfer between IL/UiO-66 interfaces. Our calculations suggest that, IL does not affect the structure of UiO-66 surface. The anion and the alkyl group in the cations play a vital role in the stability of the complexes. Furthermore, confinement effect influence the stability of the complexes, irrespective nature of anion and cation. Electron density and charge transfer analyses reveal that anions have profound liking towards MOF because of having high electronegative atoms. Our study will help to understand the molecular level interaction between IL@MOF interface, and these composite can be utilized for the energy and environment related applications.

Optimization of Triply Periodic Minimal Surface Heat Exchanger to Achieve Compactness, High Efficiency, and Low-Pressure Drop

With advancements in additive manufacturing (AM) techniques, high-quality triply periodic minimal surface (TPMS) structures can now be produced. TPMS walled heat exchangers (HX) hold significant potential for industrial applications and are receiving increasing attention. This paper explores the impact of various TPMS design variables on flow and thermal performance to optimize TPMS heat exchangers for compactness, high efficiency, and low pressure drop. The design variables examined include the type of TPMS lattice, unit cell size, wall thickness, aspect ratio, TPMS orientation, and equivalent thickness. The study reveals that the flow and heat transfer performance of TPMS structures are significantly affected by these design variables. For the Gyroid, Diamond, and SplitP lattices, performance is nearly identical when the surface-to-volume ratio is kept constant. The average velocity of the fluid in the TPMS HX should be 0.3 m/s. The corresponding Re is between 300~800. Thin wall thickness, small equivalent thickness, and flat lattice configurations can significantly reduce pressure drop while maintaining the overall heat transfer coefficient. Additionally, the angle between the flow direction and TPMS orientation can increase pressure drop. Three aluminum heat exchangers were successfully printed using an AM machine, and testing results are comparable with theoretical prediction.

Simultaneous bulk and surface modifications of g-C3N4 via supercritical CO2-assisted post-treatment towards enhanced photocatalytic activity

A high-temperature supercritical CO2 (ScCO2)-assisted post-treatment strategy is developed to simultaneously modify the bulk and surface structures of graphitic carbon nitride (g-C3N4) using ScCO2 as penetrant and a small amount of methanol/acetonitrile mixture as modifiers. Specifically, the product of modified g-C3N4 is obtained through the post-treatment of pristine g-C3N4 in a homogeneous ScCO2/methanol/acetonitrile system, continuously heating to reach a target temperature (330 °C, 15.2 MPa) without a residence time. With the assistance of ScCO2, organic molecules penetrate the interlayers of g-C3N4 and subsequently modify the in-plane structure of g-C3N4. Methanol induces the partial transformation of g-C3N4 into a carbon nitride with a poly(heptazine imide)-like structure and with abundant methyl and hydroxyl groups. Simultaneously, acetonitrile polymerizes into 2,4,6-trimethyl-1,3,5-triazine, which is then covalently grafted onto the surface of modified g-C3N4. Remarkably, the entire post-treatment process is completed within 5 min, achieving a final product yield of 92.3 %. The modified g-C3N4 photocatalyst achieves an H2-evolution rate of 2126.1 μmol·h−1·g−1 and a CO2-to-CO conversion rate of 874.1 µmol·h−1·g−1. This work provides a green, efficient, high-yield, and scalable strategy for preparing layered and porous non-metallic photocatalysts using supercritical fluids technology.

Energy–dependent femtosecond LIPSS on germanium and application in explosives sensing

Abstract In this study, we fabricated laser-induced periodic surface structures (LIPSS) on a germanium surface through laser ablation in air using axicon and femtosecond (fs) pulses. This novel approach permitted the nanoscale material processing outcome refinement via an fs Bessel beam. Our investigations aimed at systematically understanding the formation of periodic structures under various experimental conditions, such as (i) different pulse energies ranging from 50 µJ to 1000 µJ at a constant scan speed and (ii) constant energy with different scan speeds (0.1–3 mm s−1). By adjusting the fluences and scan speeds, we were able to identify the parametric space and alter the periodicity of the low-spatial frequency LIPSS and high-spatial frequency LIPSS on germanium, which were analyzed using field emission scanning electron microscopy. An optimal LIPSS formation over a large area of germanium was achieved at an input energy of 250 µJ and a scan speed of 0.75 mm s−1. Additionally, we measured the contact angles of the Ge nanostructures (GeNSs) to demonstrate their hydrophobic nature and non-wetting properties, providing insights into the behavior of LIPSS. Subsequently, the GeNSs were coated with a ∼15 nm thick gold (Au) film using a thermal deposition method. Utilizing these, the surface-enhanced Raman spectroscopy (SERS) technique detected diverse analytes, such as tetryl (an explosive) at a concentration of 50 µM and thiram (a pesticide) at 500 nM. The SERS enhancement factors for tetryl and thiram molecules on GeNSs coated with a 15 nm-thick Au layer were determined to be 2.5 × 104 and 4.2 × 105, respectively.

Effect of biosurfactants on the self-assembly behavior and drug encapsulation for branched block copolymers

For the past few years, block copolymers have attracted extensive attention in the field of drug delivery. In this work, the hyperbranched PEO-PPO block copolymer H1304 having the same PEO segments and PPO segments as the commercially available 4-branched block copolymer Tetronic1304 was synthesized. Compared with T1304, H1304 was characterized by lower cloud point, smaller critical micelle concentration (CMC), larger micellar size and better drug solubilization capacity. The effect of three biosurfactants lecithin (PC), alkyl glycogen (APG), sodium deoxycholate (NaDC) on the aggregation behavior of H1304 and T1304 were researched. Meanwhile, the solubilization and in vitro release properties of hydrophobic anticancer drug podophyllotoxin were also evaluated. The addition of PC or APG to form a mixed micelle reduced the cloud point and CMC, optimized the drug carrier characteristics. NaDC exhibited different effects due to its unique disclike surface structure. NaDC formed back-to-back aggregates, which interfered the self-assembly process of block copolymer and in turn caused variation of the copolymer micellar properties. The study of mixed systems consisting of biosurfactants and block copolymers will help to change the performance of copolymers in various pharmaceutical fields and contribute to the application of copolymers as drug carriers in drug delivery systems.

Functional and pragmatic parameters of speech acts with the explicit mode of ignorance in scientific dialogue

The article is about identifying functional aspects of 1st-person statements with the explicit mode of ignorance (messages like I do not know… / We don’t know… I don’t know / We don’t know ...) in scientific discussions as a genre of scientific discourse. The relevance of the analysis is predetermined by the necessity to study various parameters of discourse (including both epistemic and pragmatic) as closely connected. The main research method is contextual and pragmalinguistic analysis. The sources of the material are transcripts of modern English and Russian scientific discussions in various fields of knowledge. The article identifies the illocutionary properties of ignorant statements, establishes their pragmatic functions, as well as determines their position in the traditional classification of speech acts. Taking into account the illocutionary orientation of references to ignorance makes it possible to identify representative, interrogative, axiological varieties of ignorance messages as well as their subtypes differentiated on the basis of the degree of their expressiveness, their vector of evaluation, the nature of the representative and interrogative role of speech acts with the mode of ignorance: fully expressive and conditionally expressive, positive and negative, preventive and hesitative, etc. The criterion “pragmatic functions” helps us specify additional functions of references to ignorance in scientific dialogue: to indicate a certain degree of the speaker’s epistemic responsibility for their words, to serve as a means of avoiding the answer, a way to prevent criticism, etc. Moreover, the work identifies factors determining the illocutionary nature of ignorance speech acts: the surface structure of the message, the general context of utterance, the position of the ignorance message in the dialogical unity, sincerity and felicity conditions of speech acts formulated as ignorance messages. References to ignorance are concluded to be quite a significant phenomenon in the structure of scientific dialogue, since they perform a number of important functions in it. The analysis scheme can be used to study statements with other explicit modes (knowledge, opinions, etc.) in various types of discourse.

Atomic structure of different surface terminations of polycrystalline ZnPd

The intermetallic compound ZnPd has been found to have desirable characteristics as a catalyst for the steam reforming of methanol. The understanding of the surface structure of ZnPd is important to optimize its catalytic behavior. However, due to the lack of bulk single-crystal samples and the complexity of characterizing surface properties in the available polycrystalline samples using common experimental techniques, all previous surface science studies of this compound have been performed on surface alloy samples formed through thin-film deposition. In this study, we present findings on the chemical and atomic structure of the surfaces of bulk polycrystalline ZnPd studied by a variety of complementary experimental techniques, including scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), low energy electron microscopy (LEEM), photoemission electron microscopy (PEEM), and microspot low-energy electron diffraction (μ-LEED). These experimental techniques, combined with density functional theory (DFT)-based thermodynamic calculations of surface free energy and detachment kinetics at the step edges, confirm that surfaces terminated by atomic layers composed of both Zn and Pd atoms are more stable than those terminated by only Zn or Pd layers. DFT calculations also demonstrate that the primary contribution to the tunneling current arises from Pd atoms, in agreement with the STM results. The formation of intermetallics at surfaces may contribute to the superior catalyst properties of ZnPd over Zn or Pd elemental counterparts. Published by the American Physical Society 2024

Black Phosphorus for Mid-Infrared Optoelectronics: Photophysics, Scalable Processing, and Device Applications.

High efficiency mid-infrared (λ = 3-8 μm) light emitters and photodetectors are pivotal for advancing next-generation optoelectronics. However, narrow-bandgap semiconductors face fundamental challenges such as pronounced nonradiative carrier recombination and thermally generated noise, which impede device performance. Recently, two-dimensional layered black phosphorus (BP) and its alloys have attracted substantial interest for mid-infrared device applications, demonstrating superior performance relative to conventional III-V and II-VI semiconductors with similar bandgaps. In this review, we discuss the optical properties of BP, contrasting these with those of covalent compounds. Owing to its inherently self-terminated surface structure and reduced nonradiative recombination, BP exhibits high performance in light emission and photodetection at room temperature. Furthermore, this review highlights recent advances in the large-area processing of BP thin films, paving the way for practical device applications and integration. Finally, we explore ongoing challenges and emerging opportunities in the utilization of BP for functional mid-infrared devices.

Combinatorial control of type IVa pili formation by the four polarized regulators MglA, SgmX, FrzS, and SopA.

Type IVa pili (T4aP) are widespread bacterial cell surface structures with important functions in translocation across surfaces, surface adhesion, biofilm formation, and virulence. T4aP-dependent translocation crucially depends on the number of pili. To address how the number of T4aP is regulated, we focused on M. xanthus, which assembles T4aP at the leading cell pole and is a model organism for T4aP biology. Our results support a model whereby the four proteins MglA, SgmX, FrzS, and the newly identified SopA protein establish a highly intricate interaction network for orchestrating T4aP formation at the leading cell pole. This network allows for combinatorial regulation of the number of T4aP resulting in discrete levels of T4aP-dependent motility.

A Review on the Effect of Wood Surface Modification on Paint Film Adhesion Properties

Wood surface treatment aims to improve or reduce the surface activity of wood by physical treatment, chemical treatment, biological activation treatment or other methods to achieve the purpose of surface modification. After wood surface modification, the paint film adhesion performance, gluing performance, surface wettability, surface free energy and surface visual properties would be affected. This article aims to explore the effects of different modification methods on the adhesion of wood coating films. Modification of the wood surface significantly improves the adhesion properties of the paint film, thereby extending the service life of the coating. Research showed that physical external force modification improved the hydrophilicity and wettability of wood by changing its surface structure and texture, thus enhancing the adhesion of the coating. Additionally, high-temperature heat treatment modification reduced the risk of coating cracking and peeling by eliminating stress and moisture within the wood. Chemical impregnation modification utilized the different properties of organic and inorganic substances to improve the stability and durability of wood. Organic impregnation effectively filled the wood cell wall and increased its density, while inorganic impregnation enhanced the adhesion of the coating by forming stable chemical bonds. Composite modification methods combined the advantages of the above technologies and significantly improved the comprehensive properties of wood through multiple modification treatments, showing superior adhesion and durability. Comprehensive analysis indicated that selecting the appropriate modification method was key for different wood types and application environments.

Clinical Characteristics of Choroidal Metastases

The most common intraocular tumors in adults are metastases from primary tumors: breast cancer, lung cancer, and other organ neoplasms. They are most typically located in the choroid, in the posterior pole of the eye. This article outlines the characteristic clinical features along with ultrasound and optical coherence tomography findings that aid in differential diagnosis. It also illustrates the growth pattern of metastatic nodules from their formation to their eventual fusion into a diffuse tumor conglomerate with an irregularly shaped surface and internal structure