Rough Form Research Articles

Multiscale evaluation of sand-geomaterial interface shear response in terms of material geometry effects

This study evaluates the effects of particle and surface geometric features on the interface shear behavior of sand-geomaterial. Particle shape and size were adjusted for the sand, and surface roughness form and height were set for the geomaterial part. 3D printing technology was used to produce geomaterials in the desired form. A custom-made transparent interface shear box was developed to perform digital image processing. For macroscale response, peak and residual strengths and dilation angle were measured. Sliding percentage and shear band thickness were determined from digital image correlation analyses for the mesoscale response. The experimental results showed that the macroscale response parameters increased as the overall regularity of the sand particles decreased. The increase in mean particle size and roughness height led to an increase in macroscale parameters. Digital image correlation analyses showed that the sliding percentage had an inverse correlation with the shear band thickness in terms of the particle shape and the roughness height effects. The roughness form controlled the trend of mean particle size effects on the sliding percentage. Overall, the mesoscale parameters revealed the traces of interlocking response, particle kinematics, and the failure mechanism in the interface region. Thus, a bridge was established between meso- and macro-scale responses.

Experimental investigations and sustainability analysis on the performance of vegetable oil-based MQL drilling of SS316L

ABSTRACT Recently, efforts have been made to reduce the use of conventional cutting fluids. Minimum Quantity Lubrication (MQL) has become a favourable approach to enhance machining performance and sustainability. This study investigated the impact of various cutting conditions on the drilling performance of SS316L, considering surface roughness, tool wear, and chip forms. The drilling tests are performed under dry, flood, and vegetable oil-based MQL (VMQL) conditions. The drilling under the VMQL condition resulted in a desirable surface finish, as indicated by a lower Ra value of 1.81 µm for 20 holes drilled compared to the other conditions. The results highlighted the efficacy of VMQL in reducing tool wear during drilling. Furthermore, the analysis of chip quality demonstrated that VMQL produced favourable chip forms compared to flood cooling and dry machining. The enhanced lubricating and cooling mechanism enabled the creation of desired chip forms under VMQL. In summary, the study clarified the specific benefits of different machining conditions, highlighting the crucial importance of lubrication in achieving desired surface finish, chip quality, and tool wear in various machining environments. The sustainability assessment is conducted using the Pugh matrix approach, and the superiority of VMQL over other drilling conditions is found.

An Experimental Study of the Frictional Behavior at the Interface Soil-Structure with Regards to Wall Friction Effect and Clogging Related to Surface Roughness Form

Abstract The interactions between soil-structure are largely governed by the shear strength at the soil-structure interface, particularly in situations involving large displacements, known as shear residual strength. This latter can be influenced by a range of factors, including normal stress, physical properties, surface roughness, wall friction. The main objective of this study is to investigate clogging related to surface roughness form, in addition to wall friction arises from consolidation. In order to investigate the impact of wall friction, experiments involving ring shear tests were carried out on kaolin. Four different consolidation durations were employed to induce varying settlements of the upper platen, while three distinct testing procedures, including single stage, multistage, and preshearing, were utilized. Additionally, different levels of surface roughness were incorporated to investigate the effect of clogging. The test results obtained from various testing procedures indicate that employing a single stage procedure with zero consolidation time is the most suitable approach for mitigating the influence of wall friction. For clogging effect, is dependent on the materials used, namely, the kaolin and the mixture, as well as, the interfaces involved.

Elucidating optimal nanohole structures for suppressing phonon transport in nanomeshes

Nanomeshes, often referred to as phononic crystals, have been extensively explored for their unique properties, including phonon coherence and ultralow thermal conductivity (κ). However, experimental demonstrations of phonon coherence are rare and indirect, often relying on comparison with numerical modeling. Notably, a significant aspect of phonon coherence, namely the disorder-induced reduction in κ observed in superlattices, has yet to be experimentally demonstrated. In this study, through atomistic modeling and spectral analysis, we systematically investigate and compare phonon transport behaviors in graphene nanomeshes, characterized by 1D line-like hole boundaries, and silicon nanomeshes, featuring 2D surface-like hole boundaries, while considering various forms of hole boundary roughness. Our findings highlight that to demonstrate a disorder-induced reduction in κ of nanomeshes, optimal conditions include low temperature, smooth and planar hole boundaries, and the utilization of thick films composed of 3D materials.

Theoretical and experimental investigation of ultrasonic cutting kinematics and its effect on chip formation and surface generation in high-frequency ultrasonic vibration-assisted diamond cutting

Ultrasonic vibration-assisted cutting (UVAC) is regarded as a feasible technology to machine difficult-to-cut materials. High-frequency ultrasonic vibration-assisted cutting (HFUVAC), with a working frequency of more than low and medium frequency (20–60 kHz), has been reported to improve material machinability and prolong tool life. This paper presents a comprehensive investigation of the ultrasonic cutting kinematics and the generated chip/surface formation process in HFUVAC of a 316l stainless steel workpiece. First, the ultrasonic cutting kinematics was analyzed and verified by comparing the experimental and theoretical surface texture under different nominal cutting speeds. Based on the ultrasonic cutting kinematics and the simulated strain/stress distributions, the chip and surface formation between conventional cutting (CC) and HFUVAC was analyzed. More importantly, the incremental cutting mode was defined when the cutting stroke, namely the effective cutting length in one vibration cycle was less than 800 nm. The results show that in the incremental cutting mode, defect-free surface was achieved due to suppressed large deformation and friction action. Finally, HFUVAC of the sinusoidal microstructure was performed under the incremental cutting mode, achieving optical requirements with nanometer-scale surface roughness and submicrometric form accuracy, which validates the technical feasibility in HFUVAC of micro-structured surfaces.

Anticandidal Activity of a Siderophore from Marine Endophyte Pseudomonas aeruginosa Mgrv7.

An endophytic symbiont P. aeruginosa-producing anticandidal siderophore was recovered from mangrove leaves for the first time. Production was optimal in a succinate medium supplemented with 0.4% citric acid and 15 µM iron at pH 7 and 35 °C after 60 h of fermentation. UV spectra of the acidic preparation after purification with Amberlite XAD-4 resin gave a peak at 400 nm, while the neutralized form gave a peak at 360 nm. A prominent peak with RP-HPLC was obtained at RT 18.95 min, confirming its homogeneity. It was pH stable at 5.0-9.5 and thermally stable at elevated temperatures, which encourages the possibility of its application in extreme environments. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against Candida spp. Were in the range of 128 µg/mL and lower. It enhanced the intracellular iron accumulation with 3.2-4.2-fold (as judged by atomic absorption spectrometry) with a subsequent increase in the intracellular antioxidative enzymes SOD and CAT. Furthermore, the malondialdehyde (MDA) concentration due to cellular lipid peroxidation increased to 3.8-fold and 7.3-fold in C. albicans and C. tropicalis, respectively. The scanning electron microscope (SEM) confirmed cellular damage in the form of roughness, malformation, and production of defensive exopolysaccharides and/or proteins after exposure to siderophore. In conclusion, this anticandidal siderophore may be a promising biocontrol, nonpolluting agent against waterborne pathogens and pathogens of the skin. It indirectly kills Candida spp. by ferroptosis and mediation of hyperaccumulation of iron rather than directly attacking the cell targets, which triggers the activation of antioxidative enzymes.

Environmental Influences on the Detection of Buried Objects with a Ground-Penetrating Radar

A tremendous number of landmines has been buried during the last decade. In recent years, various autonomous platforms equipped with ground-penetrating radars (GPRs) have been proposed for the detection of landmines. These systems have already demonstrated their performance in controlled environments with known ground truth. However, it has been observed that the influence of surface conditions in the form of vegetation and roughness as well as soil moisture content significantly reduce the detection probability. The influence of these individual factors on a ground-offset GPR is presented and discussed in this work. Each of these factors significantly degrades the backscattered signal. With increasing soil moisture, the signal gets attenuated more strongly; however, the signature is maintained in the phase of the C-Scans. An increase in surface roughness deteriorates the target pattern making it difficult to detect buried objects unambiguously. Vegetation, especially with irregular leaf structures, can appear as a ghost target and scatter the electromagnetic waves. In most cases, the target is easier to detect in the phase of the B- or C-Scan.

Influence of bioactive glass addition on the machinability, mechanical and biological response of Mg-PSZ-based biocomposites

The incorporation of bioactive glass (BG) into zirconia-based composite materials shows a feasible option to enhance the biological properties, reduce the sintering temperature, and resist the transformation of the tetragonal phase of zirconia. In this present work, the bioceramic composites, having the general formula [(100-x) (8 Mg-PSZ) – x (13–93 BG)] where x = 0 to 25 wt%, have been prepared and evaluated the effect of BG amounts on the machinability, mechanical and biological behavior of the composite material. The machining experiment is performed on an abrasive air jet machine (AAJM), and machinability is evaluated in the form of material removal rate (MRR), surface roughness (SR), and mechanics of material erosion (MME) at room temperature. The machinability results show that MRR decreases with enhancing the BG contents, and the SR follows the opposite trend of MRR. The MME indicates that the material is removed from the surface mainly due to the erosion crater and brittle fracture. Further, mechanical properties are evaluated, and it is found that the inclusion of BG frits and sintering temperature is substantially associated with the relative densities and the mechanical characteristics. Adding BG reinforcements increases the mechanical characteristics at lower sintering temperatures (1250 °C) while reducing the mechanical characteristics except hardness at higher sintering temperatures (1350 °C). Elastic modulus decreases with the addition of BG content up to 15 wt%; after that, it slightly increases up to 25 wt%. The in-vitro bioactivity and bio-degradation are tested in simulated body fluid (SBF), and both are increased by enhancing the BG contents up to 25 wt%. The in-vitro cell culture is performed on the MG-63 cell line. The biocompatibility increases with BG concentration (up to 25 wt%). Based on experimental results, it may be concluded that 8 Mg-PSZ/13-93BG bioceramic composites may be a potential choice for biomedical applications.

Iterative dynamics-based mesh discretisation for multi-scale coastal ocean modelling

Flow in coastal waters contains multi-scale flow features that are generated by flow separation, shear-layer instabilities, bottom roughness and topographic form. Depending on the target application, the mesh design used for coastal ocean modelling needs to adequately resolve flow features pertinent to the study objectives. We investigate an iterative mesh design strategy, inspired by hydrokinetic resource assessment, that uses modelled dynamics to refine the mesh across key flow features, and a target number of elements to constrain mesh density. The method is solver-agnostic. Any quantity derived from the model output can be used to set the mesh density constraint. To illustrate and assess the method, we consider the cases of steady and transient flow past the same idealised headland, providing dynamic responses that are pertinent to multi-scale ocean modelling. This study demonstrates the capability of an iterative approach to define a mesh density that concentrates mesh resolution across areas of interest dependent on model forcing, leading to improved predictive skill. Multiple design quantities can be combined to construct the mesh density, refinement can be applied to multiple regions across the model domain, and convergence can be managed through the number of degrees of freedom set by the target number of mesh elements. To apply the method optimally, an understanding of the processes being model is required when selecting and combining the design quantities. We discuss opportunities and challenges for robustly establishing model resolution in multi-scale coastal ocean models.

Assessing the Settling Velocity of Biofilm-Encrusted Microplastics: Accounting for Biofilms as an Equivalent to Surface Roughness.

While it is well established that a biofilm contributes to the sinking of plastics, the underlying mechanisms of how it influences the vertical transport of plastics have not been well explained. In this context, our study dives into the intricate effects of biofouling on the settling velocity (Ws) of microplastics (MPs) within the fluid. We adopt the perspective that the biofilm is a form of surface roughness impacting the drag coefficient (Cd) and vertical settling of MPs. By advancing the biofouling process model, we simulate the temporal variations of density and biofilm thickness of biofouled floating MPs, accounting for realistic parameters and assuming a layer-by-layer growth of biofilm on plastisphere surfaces. MPs of polyethylene (PE) exhibit a quicker initiation of descent compared to their polypropylene (PP) counterparts. Furthermore, leveraging computational fluid dynamics (CFD) simulation, the method to predict the Cd of spherical MPs with surface roughness is established. By treating the thickness of the biofilm as roughness height, an explicit method to predict the Ws of biofouled MPs is derived. The settling experiments for biofouled MPs conducted not only support the combination of the biofouling model and the explicit method to predict the Ws of biofouled MPs but also enhance the prediction accuracy by introducing a ratio parameter Co to better relate the equivalent surface roughness height (k) to the biofilm thickness (σ), i.e., k = Co·σ, where the recommended value of Co for spherical PP and PE MPs is between 0.5 to 0.8. This study, thus, provides new insights into the dynamics of biofouled MPs in hydraulic ecosystems.

Influence of substrate surface roughness on the thermal emissivity of titanium carbide coatings on graphite

This study focused on the impact of substrates shape on the heat radiationcharacteristics of a coating made of titanium carbide, TiC, deposited over a graphite basis. The TiC coating emissivity increase by 29.65% at 1050?C and by 37.45% at 1650?C when graphite, substrate surface roughness, was decreased from 3.01 ?m to 0.73 ?m. Simultaneously, the TiC coating?s spectrum emissivity on the graphite substrate indicated the material?s clear characteristic heat radiation. These findings demonstrated that the coating and substrate interacted to determine the coating?s heat radiation properties. A simplified coating model created to consider how the shape of the substrate affects the coating?s ability to conduct heat. Ultimately, the rough form of the substrate led to a decrease in the coating?s heat radiation characteristics and an enhancement in energy loss at the interface.

Energy dissipation during homogeneous wetting of surfaces with randomly and periodically distributed cylindrical pillars

HypothesisUnderstanding contact angle hysteresis on rough surfaces is important as most industrially relevant and naturally occurring surfaces possess some form of random or structured roughness. We hypothesise that hysteresis can be described by the dilute defect model of Joanny & de Gennes [1] and that the energy dissipation occurring during the stick-slip motion of the contact line is key to developing a predictive equation for hysteresis. ExperimentsWe measured hysteresis on surfaces with randomly distributed and periodically arranged microscopic cylindrical pillars for a variety of different liquids in air. The inherent (flat surface) contact angles tested range from lyophilic (θe=33.8°) to lyophobic (θe=112.0°). FindingsA methodology for averaging the measured advancing and receding contact angles on random surfaces is presented. Based on these results correlations for roughness-induced energy dissipation are derived, and an equation for predicting the advancing and receding contact angles during homogeneous (Wenzel) wetting on random surfaces is presented. Equations that predict the onset of the alternate wetting conditions of hemiwicking, split-advancing, split-receding and heterogeneous (Cassie) wetting are also derived, thus defining the range of validity for the homogeneous wetting equation. A ‘cluster’ concept is proposed to explain the measurably higher hysteresis exhibited by structured surfaces compared to random surfaces.

Modeling of pressure losses in a cylindrical duct with rectangular ribs

AbstractIn order to improve the thermal performance of heat exchangers and air collectors, we insert various forms of artificial roughness, known as ribs, into the useful duct. These ribs promote the creation of turbulent flows and enhance heat transfer by conduction, convection and radiation.However, the introduction of these ribs leads to an increase in pressure drop, requiring higher mechanical power to pump the heat transfer fluid. This experimental study focuses on estimating, using empirical approaches, the pressure losses induced by rectangular ribs with an inclined top. The ribs are made from 0.4 mm galvanized sheet steel.An experimental set-up was designed to measure the head losses generated by the ribs, from the point of entry to the point of exit from the useful duct. Using the dimensional analysis method, correlations were established to evaluate head losses as a function of flow regime and rib geometry and configuration (including different geometries for rib arrangement over the configuration area).

A Comparative Evaluation of Class II Composite Restoration Techniques: A Systematic Review on Incremental Layering versus Bulk-Fill Approaches

This systematic review of 112 RCTs (n=89,712) compared incremental versus bulk-fill placement techniques for direct Class II composite restorations in permanent posterior teeth over ≥6 months. Meta-analyses found no significant differences between groups for retention, recurrent caries, marginal adaptation, fracture, postoperative sensitivity, surface roughness, color match, or anatomic form (p>0.05 for all). Bulk-fill had less marginal staining (p=0.01). Clinical performance correlated more with materials and protocols than placement technique. Challenges like microleakage and wear persisted long-term. Neither incremental nor bulk-fill demonstrated clear superiority across clinical outcomes over up to 7 years. Both can provide durable posterior restorations. Practitioners should use professional judgment in technique selection based on clinical factors. Further long-term RCTs are warranted to reinforce these conclusions that neither placement technique showed superior clinical performance for direct Class II composite restorations.

Automated tree ring detection of common Indiana hardwood species through deep learning: Introducing a new dataset of annotated images

Tree-ring dating enables gathering necessary knowledge about trees, and it is essential in many areas, including forest management and the timber industry. Tree-ring dating can be conducted on either wood’s clean cross-sections or tree trunks’ rough end cross-sections. However, the measurement process is still time-consuming and frequently requires experts who use special devices, such as stereoscopes. Modern approaches based on image processing using deep learning have been successfully applied in many areas, and they can succeed in recognizing tree rings. While supervised deep learning-based methods often produce excellent results, they also depend on extensive datasets of tediously annotated data. To our knowledge, there are only a few publicly available ring image datasets with annotations. We introduce a new carefully captured dataset of images of hardwood species automatically annotated for tree ring detection. We capture each wood cookie twice, once in the rough form, similar to industrial settings, and then after careful cleaning, that reveals all growth rings. We carefully overlap the images and use them for an automatic ring annotation in the rough data. We then use the Feature Pyramid Network with Resnet encoder that obtains an overall pixel-level area under the curve score of 85.72% and ring level F1 score of 0.7348. The data and code are available at https://github.com/wufanyou/growth-ring-detection.

Population heterogeneity in Mycobacterium smegmatis and Mycobacterium abscessus.

Bacteria use population heterogeneity, the presence of more than one phenotypic variant in a clonal population, to endure diverse environmental challenges - a 'bet-hedging' strategy. Phenotypic variants have been described in many bacteria, but the phenomenon is not well-understood in mycobacteria, including the environmental factors that influence heterogeneity. Here, we describe three reproducible morphological variants in M. smegmatis - smooth, rough, and an intermediate morphotype that predominated under typical laboratory conditions. M. abscessus has two recognized morphotypes, smooth and rough. Interestingly, M. tuberculosis exists in only a rough form. The shift from smooth to rough in both M. smegmatis and M. abscessus was observed over time in extended static culture, however the frequency of the rough morphotype was high in pellicle preparations compared to planktonic culture, suggesting a role for an aggregated microenvironment in the shift to the rough form. Differences in growth rate, biofilm formation, cell wall composition, and drug tolerance were noted among M. smegmatis and M. abscessus variants. Deletion of the global regulator lsr2 shifted the M. smegmatis intermediate morphotype to a smooth form but did not fully phenocopy the naturally generated smooth morphotype, indicating Lsr2 is likely downstream of the initiating regulatory cascade that controls these morphotypes. Rough forms typically correlate with higher invasiveness and worse outcomes during infection and our findings indicate the shift to this rough form is promoted by aggregation. Our findings suggest that mycobacterial population heterogeneity, reflected in colony morphotypes, is a reproducible, programmed phenomenon that plays a role in adaptation to unique environments and this heterogeneity may influence infection progression and response to treatment.

Deep-blue random lasing emission coming from the BN-heteroacenes derivatives

Blue laser light emission is one of the most desirable and pursued types of laser emission due to its rarity and high demand for blue-emitting organic devices. Despite optimization, however, such systems struggle with limited stability and intense photobleaching and are based on a limited number of compounds. Thus, we present random lasing emission acquired from transparent dye-doped thin layers containing pyrrole[3,2-b]pyrrole-based BN-heteroacenes (BNPPs) derivatives. We show that laser light generation arises from inhomogeneities in the form of surface roughness and nanocrystals of aggregates acting as centers of constructive Mie scattering.

OPTIMIZATION OF CUTTING DIRECTION PARAMETERS FOR A CNC MILLING MACHINING PROCESS POCKET ON STRUCTURE AND SURFACE ROUGHNESS ON POSTEP MOTORCYCLE SPARE PARTS

CNC Milling machine is a machine that is widely used for the manufacture of a component. Product quality will be related to product selling value and consumer satisfaction, therefore the best parameters must be known in order to produce quality products. This study aims to determine the effect of the cutting direction on the structure and surface roughness of the pocket feeding CNC Milling machining process. Experimental methods are used to improve the quality of products produced by CNC Milling machines. The parameters used in this study are variations of spindle speed 500 rpm, 1900 rpm, and 5000 rpm, as well as variations of cutting direction, namely one way and zig-zag. The tests carried out are in the form of surface roughness testing, micro-structure observations, and macro-structures. The data analysis technique used is descriptive statistics. The results obtained are the use of the cutting direction parameter affects the quality of the resulting product in the form of structure and surface roughness. The zig-zag cutting direction parameter with spindle speed 5000 rpm obtained the lowest average surface roughness value of 0.87 μm, while the one way cutting direction with spindle speed 500 rpm obtained the highest average roughness value of 2,84 μm. In conclusion, using a higher spindle speed will result in a lower roughness value, while the zig-zag cutting direction produces a lower roughness value and a more even surface structure compared to one way cutting direction.

Contrast and Fusion: The Role of Regional Culture in Shaping Jiangsu Paper-Cut Art

The Chinese paper-cut art, first recorded in the Wei, Jin, and Southern and Northern Dynasties (220 AD–589 AD), has witnessed the changes of times, yet it still retains its artistic vitality. Chinese papercuts can be divided into two schools: the northern and the southern. Jiangsu, located in the region of the Yellow River and Huai River, is the geographical dividing line between those two schools. Therefore, in Jiangsu Province, not only the rough northern art form (such as in Xuzhou papercut) but also the graceful southern art form (such as in Jintan papercut) is evident. In addition, the unique combined paper-cut style (such as in Yangzhou and Nanjing papercuts) can be appreciated here. Although several scholars have analyzed the artistic characteristics of Jiangsu papercut based on cultural background, very few have discussed the differences between the northern and the southern in terms of content, connotation, and style. Through literature review and collected works made by local craftsmen and inheritors of this tradition, this article aims to show readers the contrast and integration of papercuts in these four places under the influence of different cultural and economic backgrounds in order to better understand the role of regional factors in shaping the art form of papercuts in Jiangsu Province. Nowadays, with the change in people’s lifestyles, the living space of traditional papercuts has shrunk drastically, and its practicability in the past has faded. Instead, people are searching for and creating cultural and artistic value in museums, tourist attractions, and commodity transactions. Among them, some works have deviated from the cultural background of traditional paper-cut art. Therefore, this paper provides a basis for the current development of this art form in Jiangsu.

Mycobacterium abscessus resists the innate cellular response by surviving cell lysis of infected phagocytes.

Mycobacterium abscessus is the most pathogenic species among the predominantly saprophytic fast-growing mycobacteria. This opportunistic human pathogen causes severe infections that are difficult to eradicate. Its ability to survive within the host was described mainly with the rough (R) form of M. abscessus, which is lethal in several animal models. This R form is not present at the very beginning of the disease but appears during the progression and the exacerbation of the mycobacterial infection, by transition from a smooth (S) form. However, we do not know how the S form of M. abscessus colonizes and infects the host to then multiply and cause the disease. In this work, we were able to show the hypersensitivity of fruit flies, Drosophila melanogaster, to intrathoracic infections by the S and R forms of M. abscessus. This allowed us to unravel how the S form resists the innate immune response developed by the fly, both the antimicrobial peptides- and cellular-dependent immune responses. We demonstrate that intracellular M. abscessus was not killed within the infected phagocytic cells, by resisting lysis and caspase-dependent apoptotic cell death of Drosophila infected phagocytes. In mice, in a similar manner, intra-macrophage M. abscessus was not killed when M. abscessus-infected macrophages were lysed by autologous natural killer cells. These results demonstrate the propensity of the S form of M. abscessus to resist the host's innate responses to colonize and multiply within the host.