Wall Pattern Research Articles

Micromorphological Characterization of Seeds of Dicot Angiosperms from the Thal Desert (Pakistan)

Micromorphological and ultrastructural data have been helpful in determining the evolution, classification, ecology, and phylogeny of seed plants. Taxonomic utility of seed characters has been explored, although the value of micro-structure in selected dicot angiosperms from desert areas has not been adequately addressed. We conducted a comparative morphometric analysis of internal and external seed features in the 16 dicot species representing 10 families from the Thal desert (Pakistan) using scanning electron microscopy. Seeds were mostly minute and small and slightly larger than 1 mm in length except for Acacia nilotica, Astragalus hamosus and Prosopis juliflora. Seeds varied in shape from elliptical to obovate, D-shaped, reniform, rhomboid, and ellipsoidal. The cell outline, periclinal boundaries, and sculpture pattern of the anticlinal wall were generally rugulate, reticulate and striate, papillate and rugose, or rarely undulating granulate. The seed coat also comprises diverse forms of epicuticular projections and texture. The phenetics of 84 character-states using principal component and dendrogram statistics supported the affinities among desert species. Here, we identified micromorphological similarities and differences among dicot angiosperms to determine their systematic relationships.

Influence of Pipe-Jacking Reaction on Earth Pressure of Back Wall of Pilot Tunnel of Subway Station

The study of the distribution form and calculation method of the earth pressure on the back wall of a pilot tunnel under a jacking reaction is very important to ensure the safety and smooth construction of the pipe jacking. Based on a metro station in Shenyang, this paper firstly investigates the effects of the changes in the jacking reaction parameters, such as the loading intensity, loading position, and loading area on the earth pressure and the displacement of the back wall in a pilot tunnel through numerical simulation, and then proposes a formula for calculating the soil reaction on the back wall and verifies it by comparison with the FEA (finite element method) results. The results show that the earth pressure distribution pattern of the back wall is similar to the normal distribution curve under the action of the jacking reaction. The horizontal displacement and earth pressure of the back wall will gradually increase with the increase in the jacking reaction. The horizontal displacement of the back wall is greatest when the load is applied to the middle wall, followed by the top wall and the bottom wall. The maximum horizontal displacement is reduced by approximately 24.25% when the loading position changes from the middle to the bottom. As the loading area increases, the maximum horizontal displacement of the back wall decreases, in the order of 11.8% and 14.45% relative to the previous level. The earth pressure of the back wall also decreases, in the order of 17.92% and 22.76% relative to the previous level. The equations presented are applicable to the calculation of the soil reaction in the limit state.

Characteristics of Leaf Epidermis of 22 Lilieae (Liliaceae) under Different Altitudes in China

In this study, 22 leaf samples of 22 Lilieae species were collected in six Province at 90 - 3740 m to study the variations of leaf characteristics with altitude change. The Qualitative character of leaf epidermis and two stomatal indexes, viz. stomatal area (SA), stomatal index (SI), were analyzed in laboratory. The results show that: 1) the shape of the leaf epidermis cells and the pattern of the anticlinal walls provide some useful taxonomic information to distinguish the genus, however, none of the stable traits are exclusive to a genus; 2) there are significant or even very significant linear correlations between the two indexes and altitude, of which SA exhibit a negative correlation with altitude (r2 = 0.294, p = 0.009), while SI exhibit a positive correlation with altitude (r2 = -0.254, p = 0.017). As a result, the pattern of leaf cells and anticlinal walls is influenced by genetic factors, while the stomatal area and stomatal index are influenced by environmental factors. Members of the tribe Lilieae have a relatively stable elevation range, which is related to their long-term adaptation to the local environment in the structure of their leaf epidermis.

73 WHICH IS THE CULPRIT OF THIS MYOCARDIAL INFILTRATION?

Abstract Introduction Myocardial infiltration by primary cardiac neoplasm is a rare condition and the pathological spectrum includes more widespread benign cell types, providing exceptional diagnostic and therapeutic challenges. Refractory heart failure, pericardial effusion and arrhythmias due to infiltrative mass are the most common clinical manifestations. Multimodality imaging, with echocardiography, computed tomography and magnetic resonance imaging, is essential to determine the characteristics of a cardiac tumor. Clinical case: A 35-year-old man without cardiovascular risk factors presented with two months of shortness of breath and weight loss. A previous history of acute myeloid leukemia undergoing allogenic bone marrow transplant was reported. Transthoracic echocardiography revealed an apical thrombus in left ventricle with inferior and septal hypokinesia conditioning mildly reduced ejection fraction, circumferential pericardial effusion without cardiac tamponade and abnormal right ventricular thickening (Figure 1). The cardiac magnetic resonance imaging confirmed diffuse thickening of the right ventricular free wall (maximum diameter 30 mm), suspected for myocardial infiltration, extending to the right atrium and left ventricle with an ischemic pattern of the inferior wall (Figure 2). No coronary artery disease was found by coronary angiography, but the right coronary artery was incorporated by the pathological tissue in chest computed tomography scan. Cardiac positron emission tomography demonstrated the presence of neoplastic tissue with increased metabolic activity, whose similar characteristics were also evident in the ascending aorta and aortic arch. Being the percutaneous endomyocardial biopsy inconclusive, a pericardiectomy was performed through a median sternotomy incision, showing widespread cardiac neoplastic infiltration. Histopathological analysis, done on samples taken by surgical myocardial biopsy, revealed tissue involvement by a rare and aggressive cardiac anaplastic large T-cell non-Hodgkin lymphoma (ALK -, Ki-67 90%). Few days after surgery, the patient developed a refractory cardiogenic shock and unluckily died before establishing an adequate therapy. Conclusion Primary cardiac lymphoma is very infrequent and the non-specificity of the symptoms makes the diagnosis extremely challenging and often limited to autopsy findings. Our case highlights the importance of an appropriate diagnostic algorithm that can allow an early diagnosis and an adequate therapy of this otherwise fatal pathology. In this condition surgical removal of the tumor in not indicated, being chemotherapy the only effective treatment. However, because of rarity, data are lacking to produce definitive regarding guidelines.

Microtubule nucleation complex behavior is critical for cortical array homogeneity and xylem wall patterning

Plant cell walls are versatile materials that can adopt a wide range of mechanical properties through controlled deposition of cellulose fibrils. Wall integrity requires a sufficiently homogeneous fibril distribution to cope effectively with wall stresses. Additionally, specific conditions, such as the negative pressure in water transporting xylem vessels, may require more complex wall patterns, e.g., bands in protoxylem. The orientation and patterning of cellulose fibrils are guided by dynamic cortical microtubules. New microtubules are predominantly nucleated from parent microtubules causing positive feedback on local microtubule density with the potential to yield highly inhomogeneous patterns. Inhomogeneity indeed appears in all current cortical array simulations that include microtubule-based nucleation, suggesting that plant cells must possess an as-yet unknown balancing mechanism to prevent it. Here, in a combined simulation and experimental approach, we show that a limited local recruitment of nucleation complexes to microtubules can counter the positive feedback, whereas local tubulin depletion cannot. We observe that nucleation complexes preferentially appear at the plasma membrane near microtubules. By incorporating our experimental findings in stochastic simulations, we find that the spatial behavior of nucleation complexes delicately balances the positive feedback, such that differences in local microtubule dynamics-as in developing protoxylem-can quickly turn a homogeneous array into a banded one. Our results provide insight into how the plant cytoskeleton has evolved to meet diverse mechanical requirements and greatly increase the predictive power of computational cell biology studies.

Utility of high-resolution magnetic resonance vessel wall imaging in differentiating between atherosclerotic plaques, vasculitis, and arterial dissection

PurposeDifferentiating between atherosclerosis, vasculitis, and dissection is a diagnostic challenge because of inconclusive findings on conventional imaging and some overlap in the vessel wall patterns. The aim of this study was to determine whether vessel wall MRI patterns can differentiate between these vasculopathies.MethodsWe retrospectively reviewed 3T high-resolution vessel wall imaging studies of patients diagnosed with atherosclerotic plaques, vasculitis, and dissection. The patterns of involvement, wall enhancement, and T1 and T2 signals, as well as the specific patterns, were assessed and compared between the three diseases.ResultsFifty-nine patients with atherosclerosis (n = 33), vasculitis (n = 13), and dissection (n = 13) were enrolled. There were significant differences in the pattern of involvement between the three groups (P < 0.001), with concentric wall thickening in vasculitis patients (84.6%) and eccentric wall thickening in atherosclerosis (97%) and dissection (92.3%) patients. There was also a significant difference in the specific pattern (P < 0.001), with intimal flap (76.9%) and intramural hematoma (23.1%) in dissection patients and intraplaque hemorrhage (18.2%) in atherosclerosis patients. Furthermore, subgroup analysis showed a significant difference in the wall enhancement pattern between atherosclerosis and vasculitis patients (P < 0.05). Finally, there was a significant difference in the location of involvement between the three groups (P < 0.001).ConclusionBy using the pattern of involvement, wall enhancement, and specific patterns, vessel wall MRI can help differentiate between atherosclerosis, vasculitis, and dissection.

Process Parameter Optimization of Additively Manufactured Parts Using Intelligent Manufacturing

Additive manufacturing is the technique of combining materials layer by layer and process parameter optimization is a method used popularly for achieving the desired quality of a part. In this paper, four input parameters (layer height, infill density, infill pattern, and number of perimeter walls) along with their settings were chosen to maximize the tensile strength for a given part. Taguchi DOE was used to generate an L27 orthogonal array which helped to fabricate 27 parts on the Ender 3 V2 fused deposition modeling (FDM) printer. The ultimate testing machine was used to test all 27 samples to generate the respective tensile strength values. Next, the Microsoft Azure ML database was used to predict the values of the tensile strength for various input parameters by using the data obtained from Taguchi DOE as the input. Linear regression was applied to the dataset and a web service was deployed through which an API key was generated to find the optimal values for both the input and output parameters. The optimum value of tensile strength was 22.69 MPa at a layer height of 0.28 mm, infill density of 100%, infill pattern of honeycomb, and the number of perimeter walls as 4. The paper ends with the conclusions drawn and future research directions.

Vessel wall imaging features of Moyamoya disease in a North American population: patterns of negative remodelling, contrast enhancement, wall thickening, and stenosis

BackgroundThis study characterized vessel wall imaging (VWI) features of Moyamoya disease (MMD) in a predominantly adult population at a North American center.MethodsConsecutive patients with VWI were included. Twelve arterial segments were analyzed for wall thickening, degree and pattern of contrast enhancement, and remodeling.ResultsOverall, 286 segments were evaluated in 24 patients (mean age = 36.0 years [range = 1–58]). Of 172 affected segments, 163 (95%) demonstrated negative remodeling. Complete vessel wall obliteration was most frequent in the proximal M1 (17/48, 35%). Affected segments enhanced in 72/172 (42%) (n = 15 for grade II; n = 54 for concentric and n = 18 for eccentric); 20 of 24 (83%) patients had at least one enhancing segment. Both enhancing and non-enhancing segments were present in 19/20 (95%) patients. Vessel wall enhancement was most common in the proximal segments and correlated to the degree of stenosis (p < 0.001), and outer wall diameter (p < 0.001), but not disease duration (p = 0.922) or Suzuki score (p = 0.477). Wall thickening was present in 82/172 (48%) affected segments and was associated with contrast enhancement (p < 0.001), degree of stenosis (p < 0.001), and smaller outer wall diameter (p = 0.004).ConclusionThis study presents VWI findings in North American patients with MMD. Negative remodeling was the most common finding. Most patients had both enhancing and non-enhancing abnormal segments. Vessel wall enhancement was most common in proximal segments, variable in pattern or degree and was correlated to the degree of stenosis and smaller outer wall diameter.

Experimental and numerical investigation of 3D-printed mortar walls under uniform axial compression

This study aims to investigate and trace the behavior of 3D-printed load-bearing walls under uniform axial compression load. The manufacturing procedure of 3D-printed structures is unique as they are printed layer by layer where the interface between layers is usually a weak plane for 3D-printed structures. This weak plane also causes the printed mortar to behave as an orthotropic material. To analyze and trace the behavior of 3D-printed structures, the basic mechanical properties of the 3D-printed mortar as well as the interface strength between printed layers are investigated in this study. In addition, a series of load tests on 3D-printed load-bearing walls were performed to investigate the behavior of this kind of printed structure under uniform axial compression load. There are three different printing wall patterns tested in this study, plain, diamond, and carp walls. Both diamond and carp walls failed by buckling of the printed mortar. However, with a better load transfer path of the diamond wall, the diamond wall showed a more ductile response compared to the carp wall. The diamond wall requires less printing time and less mortar consumption, but it shows a higher load at first crack, higher load-carrying capacity, and more ductile response compared to the other two walls, depicting its better overall performance as a load-bearing wall. This research also proposes an FE model which considers the interface strength of the 3D-printed layers. The proposed model can be used to predict the load–displacement, stress–strain distribution, load transfer path as well as failure pattern of the tested 3D-printed walls with satisfactory accuracy. The model can also capture well a complex geometrical non-linearity of the printed wall observed through buckling of the tested walls.

Virtual disease landscape using mechanics-informed machine learning: Application to esophageal disorders

Esophageal disorders are related to the mechanical properties and function of the esophageal wall. Therefore, to understand the underlying fundamental mechanisms behind various esophageal disorders, it is crucial to map mechanical behavior of the esophageal wall in terms of mechanics-based parameters corresponding to altered bolus transit and increased intrabolus pressure. We present a hybrid framework that combines fluid mechanics and machine learning to identify the underlying physics of various esophageal disorders (motility disorders, eosinophilic esophagitis, reflux disease, scleroderma esophagus) and maps them onto a parameter space which we call the virtual disease landscape (VDL). A one-dimensional inverse model processes the output from an esophageal diagnostic device called the functional lumen imaging probe (FLIP) to estimate the mechanical “health” of the esophagus by predicting a set of mechanics-based parameters such as esophageal wall stiffness, muscle contraction pattern and active relaxation of esophageal wall. The mechanics-based parameters were then used to train a neural network that consists of a variational autoencoder that generated a latent space and a side network that predicted mechanical work metrics for estimating esophagogastric junction motility. The latent vectors along with a set of discrete mechanics-based parameters define the VDL and formed clusters corresponding to specific esophageal disorders. The VDL not only distinguishes among disorders but also displayed disease progression over time. Finally, we demonstrated the clinical applicability of this framework for estimating the effectiveness of a treatment and tracking patients' condition after a treatment.

Ultra-sculpturing of seed morphotypes in selected species of genus Salvia L. and their taxonomic significance.

The taxonomic importance of macromorphological and micromorphological seed characteristics was investigated using SEM of ten species of the Salvia genus from Pakistan. The aim was to identify diagnostic seed ultrastructural features that could aid in species delimitation, correct identification and phylogenetic position. The ultrastructure of Salvia varies greatly, and a wide range of unique micromorphological features have been observed. Seed micromorphological features were explored by SEM, including seed shape, colour, texture, cell outline, surface sculpturing, epidermal cell arrangement, anticlinal, and periclinal wall pattern. Seed shapes were categorized as obovate, spherical, spheroid, broadly elliptic, elliptic and oblong, mostly with a terminal hilum. Seed colours were black, light brown, dark brown, brown and yellow. Exo-morphological characters, i.e. epidermal cell arrangements, included irregular, wavy pentagonal-hexagonal, regular pentagonal-hexagonal. Cluster analysis was used to assess similar and distinct species within Salvia with a feasible explanation. Taxonomic keys were made based on micromorphological qualitative features that help to delimit species and identify them quickly within the Salvia genus. Seed morphology of ten Salvia species was described and investigated, and the diagnostic significance of features evaluated using SEM. This study analysed seed features, especially at the species level, which might provide much new taxonomic information. The results revealed that, in seed morphology, using SEM can help with taxon identification, especially at the genus and species levels.

Leaf Epidermal Traits of Selected Euphorbiaceae and Phyllanthaceae Taxa of Hainan Island and Their Taxonomic Relevance

Euphorbiaceae and Phyllantaceae are two of the most taxonomically complex and diverse families among angiosperm. Therefore, this study aims to identify the common, variation, and diagnostic traits of foliar anatomy and micromorphology of selected Euphorbiaceae and Phyllanthaceae taxa collected from Hainan Island. A total of 42 individuals of 38 species belonging to these two families were examined under light microscopy (LM) and scanning electron microscopy (SEM). A multivariate detrended correspondence analysis (DCA), principal component analysis (PCA), and chord diagram analysis were performed to visualize the variations and relationships between the species. The nonglandular trichomes were further classified into long falcate and short conical with papillae on their surface, and stellate and lepidote subentire, while the glandular trichomes were divided into capitate, subsessile capitate, sessile capitates, and peltate. The paracytic-type stomata were found in most of the species. The prominent continuous or discontinuous cuticular striations radiating from the guard cells in parallel, horizontal, or reticulate patterns were analyzed in most of the taxa. Variation was also found in epidermal cells and anticlinal wall patterns. Together, these traits are useful for identification, discrimination, and to define species boundaries at various levels. Our study will provide a basis for future studies to strengthen the systematic of Euphorbiaceae taxa.

Effect of flanges on the in-plane behavior of the masonry walls

In unreinforced masonry buildings, load bearing walls are not of only rectangular shape in the plan, but the cross walls connected to them make the walls of either I shape, T shape, C shape, etc. The presence of the cross walls can significantly change the behavior of the masonry walls in terms of strength and the failure modes of the walls. In this paper, a parametric study has been performed to investigate the effect of different parameters, namely pre-compressions, material properties, aspect ratios, and boundary conditions on the in-plane behavior of the masonry walls. The masonry walls have been modeled using the simplified micro-modeling approach in the standard finite element software Abaqus without any user-defined subroutine. It has been found that the strength and damage pattern of the flanged walls are different from the rectangular walls, which needs to be considered in the analysis of masonry walls using a numerical approach or while conducting experiments.

Case history on excessively large displacements and remediation of pile-supported excavation in a sloping ground

Pile-supported excavations in urban region slopes can result in excessively large retaining wall and ground surface displacements if not strutted or tied back correctly. Such an example is presented in this study showing the details of investigation works, construction procedure, monitoring, and 3D numerical analysis of a deep excavation in a stiff clay slope. Total excavation depth ranged from 4.8 m to 5.3 m, with additional 2.0 m high vertical wall and 2.8 m high steep slope in the vicinity of the pile capping beam. Before reaching the bottom of the designed excavation, the maximum cumulative monitored wall displacements were 115.0 mm, while the cracks observed on the nearby uphill structures exceeded 5.0 mm in width. Detailed field inspections and the 3D numerical analysis were performed to investigate the displacement pattern of the pile wall and the adjacent soil and structures in the uphill area. The numerical model results were further used to define specific supporting measures to enable excavation and building construction. Supporting measures were presented, and their effectiveness was assessed. Finally, the lessons learned were summarized to prevent future failures of similar structures.

Taxonomic implications of foliar epidermal anatomy of Jatropha tanjorensis J.L. Ellis &amp; Saroja and its putative parents

This study was aimed to determine the relationship among three Jatropha taxa for their reliable identification. Data from reviews showed that J. curcas and J. gossipifolia are the putative parents of J. tanjorensis. Standard method of using Premier Light Microscope, concentrated Trioxonitrate (V) acid, Petri dishes, Methyl-blue and glycerol was employed to carry out the study. Results of the study showed that the three taxa possessed paracytic stomata on both surfaces except in J. gossipifolia where the stomata were only observed on abaxial surface. The cell shape was oblong in J. tanjorensis with undulate anticlinal wall patterns. In J. curcas and J. gossipifolia, the cell shapes and anticlinal wall patterns were irregular and straight, respectively. The stomatal length of the taxa ranged from 11.2 μm to 43.0 μm while the cell length was from 25.0 μm to 84.0 μm. The oblong cell shape and undulate anticlinal walls of J. tanjorensis are its diagnostic characters while the irregular cell shape and amphistomatic leaves are the diagnostic features of J. curcas. Absence of stomata on the adaxial surface with irregular cell shape is unique to J. gossipifolia. The data obtained could be used in conjunction with other characters for reliable identification of the three taxa.

Hard antiphase domain boundaries in strontium titanate unravelled using machine-learned force fields

We investigate the properties of hard antiphase boundaries in ${\mathrm{SrTiO}}_{3}$ using machine-learned force fields. In contrast to earlier findings based on standard ab initio methods, for all pressures up to $120\phantom{\rule{0.16em}{0ex}}\mathrm{kbar}$ the observed domain wall pattern maintains an almost perfect N\'eel character in quantitative agreement with Landau-Ginzburg-Devonshire theory, and the in-plane polarization ${P}_{3}$ shows no tendency to decay to zero. Together with the switching properties of ${P}_{3}$ under reversal of the N\'eel order parameter component, this provides hard evidence for the presence of rotopolar couplings. The present approach overcomes the severe limitations of ab initio simulations of wide domain walls and opens avenues toward concise atomistic predictions of domain-wall properties even at finite temperatures.

Investigation of Seismic Performance for Low-Rise RC Buildings with Different Patterns of Infill Walls

Evaluating the structural performance of low-rise RC buildings with infill walls is an essential issue in Thailand, as most infill walls were not designed for lateral load resistance. The purpose of this study was to predict the structural behavior and illustrate the effects of infill walls. Residential, commercial, and educational buildings were selected as representative buildings with different patterns of infill walls. Based on the results, infill walls contributed to considerable strength and stiffness. Most of the infill walls that affected the low-rise buildings were at the ground floor level. The behavior of the buildings that had a contribution of infill walls was found to be brittle until the infill walls collapsed, and then the buildings became ductile. Some patterns in which infill walls were placed improperly led to a torsional effect, resulting in columns in the affected areas reaching failure criteria more than those without this effect. Considering the NLRHA procedure, only infill walls on the ground floor contributed to the building being subjected to a ground motion. The fully infilled frame tended to reach the infill crack before the other patterns. For the UMRHA procedure, only the first vibration mode was adequate to predict seismic responses, such as roof displacement and top-story drift.

Numerical Study of an Improved Non-Circular MC Fuelled with H/Air for Thermo-Photovoltaic (TPV) Applications

In recent years, researchers have paid special attention to wall uniformity temperature and improvement in a micro-combustor (MC) for applications as thermos-photovoltaic (TPV) since they have a direct influence on feasibility and efficiency of the required conversion of energy. Numerous experimentation and numerical studies in the field of micro-combustion have been carried out and published in this respect. This study focuses on the flame and flow behaviour in an improved MC. Utilizing the famous approach of fluid dynamics being computational (CFD), the impact of geometrical flow parameters behaviour and temperature of wall is explored and measured. The generated model is being used to evaluate the effects of Hydrogen (H) mass flow rate (MFR) and H/air equivalency ratios on the flame pattern and outer temperature of wall of conventional and enhanced MCs. Moreover, the influence of various MC cross sections (CS), such as square, circular, and flat, on temperature of wall is examined. The findings reveal that when the MFR rises, the wall outside temperature rises as well. The MC with flat cross-sections (CSs) is found to be more effective in terms of power of emitter and efficiency of emitter.

Multiple instance convolutional neural network for gallbladder assessment from laparoscopic images.

We present an artificial intelligence framework for vascularity classification of the gallbladder (GB) wall from intraoperative images of laparoscopic cholecystectomy (LC). A two-stage Multiple Instance Convolutional Neural Network is proposed. First, a convolutional autoencoder is trained to extract feature representations from 4585 patches of GB images. The second model includes a multi-instance encoder that fetches random patches from a GB region and outputs an equal number of embeddings that feed a multi-input classification module, which employs pooling and self-attention mechanisms, to perform prediction. The evaluation was performed on 234GB images of low and high vascularity from 68 LC videos. Thorough comparison with various state-of-the-art multi-instance and single-instance learning algorithms was performed for two experimental tasks: image- and video-level classification. The proposed framework shows the best performance with accuracy 92.6%-93.2% and F1 93.5%-93.9%, close to the agreement of two expert evaluators (94%). The proposed technique provides a novel approach to classify LC operations with respect to the vascular pattern of the GB wall.

Numerical analysis of the two‐phase steam‐air heat transfer flow induced in smooth and corrugated channel using the VOF model

AbstractIn this paper, heat transfer induced in smooth and wavy channels in the presence of two phases (air and steam) was conducted and discussed. Two configurations have been studied according to the geometrical shape of the channel walls. The thermal and hydrodynamic fields in the channel have been predicted using the single‐fluid approach with a solver based on the finite volume method. Explicit formulation of the volume of fluid was used to track the interface between both fluids. The mesh in the wavy channel was treated with a curvilinear mesh grid. Local Nusselt evolution, isothermal distribution, streamlines, and other parameters have been shown at different times of simulation. It was found that weak air phase velocities and wave patterns of the channel walls play a destabilizing role in the interface evolution between both fluid phases. In addition, results show that channels with wavy walls can be an effective solution to ensure higher heat transfer in two‐phase flows.