Minimum Potential Research Articles

Variational modeling of temperature induced and cooling-rate dependent phase transformations in polycrystalline steel

Phase transformations in steel have a high impact on the material properties. The material is modified by a changed stiffness as well as residual stresses which are a result of transformation strains and plastic deformations during the phase transition. In the current work, we propose a variational material model which is able to display the phase transformations which occur during thermal processes like induction hardening and grinding. Depending on the cooling rate, the material model is able to show the transformation between austenite and martensite, austenite and ferrite as well as a mixture of both. The polycrystalline structure of the steel is taken into account by use of different oriented grains which are considered by a combined Voigt–Reuss bound for the energy of the phase and grain mixture. The material model is derived using the principle of the minimum of the dissipation potential for non-isothermal problems. Compared to classical approaches in material science, the model is thermomechanically coupled. Thus, the phase transformation is also influenced by the stress state and individual martensitic variants are favored during the transformation process, which is an important property for applications to process chains. The model’s ability to show the complex material behavior is proven by calculations on the material point level as well as by finite element simulations.

Rectification in a mixture of active and passive particles subject to a ratchet potential

We study by simulation a mixture of active (run-and-tumble) and passive (Brownian) particles with repulsive exclusion interactions in one dimension, subject to a ratchet (smoothed sawtooth) potential. Such a potential is known to rectify active particles at one-body level, creating a net current in the ‘easy direction’. This is the direction in which one encounters the lower maximum force en route to the top of a potential barrier. The exclusion constraint results in single-file motion, so the mean velocities of active and passive particles are identical; we study the effects of activity level, Brownian diffusivity, particle size, initial sequence of active and passive particles, and active/passive concentration ratio on this mean velocity (i.e. the current per particle). We show that in some parameter regimes the sign of the current is reversed. This happens when the passive particles are at high temperature and so would cross barriers relatively easily, and without rectification, except that they collide with ‘cold’ active ones, which would otherwise be localized near the potential minima. In this case, the reversed current arises because hot passive particles push cold active ones preferentially in the direction with the lower spatial separation between the bottom and top of the barrier. A qualitatively similar mechanism operates in a mixture containing passive particles of two very different temperatures, although there is no quantitative mapping between that case and the systems studied here.

Application of Galerkin iterative technique to nonlinear bending response of three-directional functionally graded slender beams subjected to hygro-thermal loads

In the view of some progressive devices such as shuttles in the aerospace field, the vessels in the marine engineering and reaction equipments in the nuclear field are exposed to super-high thermal or hygro-thermal loads simultaneously varied along the three directions in the operation, we propose the three-directional functional graded materials (3D FGMs) to carry out the composition of slender beams to meet the requirements of the hygro-thermal distribution in the multi-directions and improve the endural ability so that catastrophic failure is refrained due to large deflections. Built up on von Kármán geometric nonlinearity, one takes advantages of the principle of minimum total potential energy to derive the nonlinear governing equation of the structures subjected to hygro-thermal loadings of the uniform, linear and sinusoidal distributions. A novel analytical solution for the nonlinear bending response is presented based on the Galerkin iterative technique, which overcomes the shortcoming of finding difficultly the closed-form solution to antisymmetric nonlinear structures such as multi-directional FGMs. The generalized differential quadrature method (GDQM) is performed for validating the effectiveness of the presented methodology. Numerical simulations are implemented to reveal the effects of 3D FGMs indexes, mechanical and hygro-thermal loadings on the nonlinear bending response. Results exhibit the nonlinear behavior is profoundly dependent on the 3D FGMs and hygro-thermal properties, which is applied for optimizing the 3D FGMs structures in multiple physical fields.

On variational principles in coupled strain-gradient elasticity

Strain-gradient elasticity is a special case of high-gradient theories in which the potential energy density depends on the first and second gradient of the displacement field. The presence of a coupling term in the material law leads to a non-diagonal quadratic form of the stored energy, which makes it difficult for the derivation of fundamental theorems. In this article, two variational principles of the minimum of potential and complementary energies are argued in the context of the coupled strain-gradient elasticity theory. The basis of the proofs of both variational principles is the equivalent transformation of the stain and strain-gradient energy density that allows to avoid the complication related to the presence of the fifth-rank coupling tensor in the equation for the potential energy density and leads to diagonalization of the quadratic form of the stored energy. This transformation enables to inverse Hook’s law, to determine compliance tensors, and to obtain closed-form relation for the complementary energy. After that the proofs of both principles of a minimum of potential and complementary energies are provided in the usual manner adopted in the classical theory of elasticity.

Structure and kinematics of tidally limited satellite galaxies in LCDM

ABSTRACT We use N-body simulations to model the tidal evolution of dark matter-dominated dwarf spheroidal galaxies embedded in cuspy Navarro-Frenk-White subhaloes. Tides gradually peel off stars and dark matter from a subhalo, trimming it down according to their initial binding energy. This process strips preferentially particles with long orbital times, and comes to an end when the remaining bound particles have crossing times shorter than a fraction of the orbital time at pericentre. The properties of the final stellar remnant thus depend on the energy distribution of stars in the progenitor subhalo, which in turn depends on the initial density profile and radial segregation of the initial stellar component. The stellar component may be completely dispersed if its energy distribution does not extend all the way to the subhalo potential minimum, although a bound dark remnant may remain. These results imply that ‘tidally limited’ galaxies, defined as systems whose stellar components have undergone substantial tidal mass-loss, neither converge to a unique structure nor follow a single tidal track. On the other hand, tidally limited dwarfs do have characteristic sizes and velocity dispersions that trace directly the characteristic radius (rmx) and circular velocity (Vmx) of the subhalo remnant. This result places strong upper limits on the size of satellites whose unusually low velocity dispersions are often ascribed to tidal effects. In particular, the large size of kinematically cold ‘feeble giant’ satellites like Crater 2 or Antlia 2 cannot be explained as due to tidal effects alone in the Lambda Cold Dark Matter scenario.

Wood density and hydraulic traits influence species' growth response to drought across biomes.

Tree species display a wide variety of water-use strategies, growth rates and capacity to tolerate drought. However, if we want to forecast species capacity to cope with increasing aridity and drought, we need to identify which measurable traits confer resilience to drought across species. Here, we use a global tree ring network (65species; 1931site series of ring-width indices-RWI) to evaluate the relationship of long-term growth-drought sensitivity (RWI-SPEI drought index relationship) and short-term growth response to extreme drought episodes (resistance, recovery and resilience indices) with functional traits related to leaf, wood and hydraulic properties. Furthermore, we assess the influence of climate (temperature, precipitation and climatic water deficit) on these trait-growth relationships. We found a close correspondence between the long-term relationship between RWI and SPEI and resistance and recovery of tree growth to severe drought episodes. Species displaying a stronger RWI-SPEI relationship to drought and low resistance and high recovery to extreme drought episodes tended to have a higher wood density (WD) and more negative leaf minimum water potential (Ψmin). Such associations were largely maintained when accounting for direct climate effects. Our results indicate that, at a cross-species level and global scale, wood and hydraulic functional traits explain species' growth responses to drought at short- and long-term scales. These trait-growth response relationships can improve our understanding of the cross-species capacity to withstand climate change and inform models to better predict drought effects on forest ecosystem dynamics.

In Vivo Antistress Effects of Synthetic Flavonoids in Mice: Behavioral and Biochemical Approach.

Natural flavonoids, in addition to some of their synthetic derivatives, are recognized for their remarkable medicinal properties. The present study was designed to investigate the in vitro antioxidant and in vivo antistress effect of synthetic flavonoids (flavones and flavonols) in mice, where stress was induced by injecting acetic acid and physically through swimming immobilization. Among the synthesized flavones (F1–F6) and flavonols (OF1–OF6), the mono para substituted methoxy containing F3 and OF3 exhibited maximum scavenging potential against DPPH (2,2-diphenyl-1-picrylhydrazyl) with IC50 of 31.46 ± 1.46 μg/mL and 25.54 ± 1.21 μg/mL, respectively. Minimum antioxidant potential was observed for F6 and OF6 with IC50 values of 174.24 ± 2.71 μg/mL and 122.33 ± 1.98 μg/mL, respectively, in comparison with tocopherol. The ABTS scavenging activity of all the synthesized flavones and flavonols were significantly higher than observed with DPPH assay, indicating their potency as good antioxidants and the effectiveness of ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) assay in evaluating antioxidant potentials of chemical substances. The flavonoids-treated animals showed a significant (* p < 0.05, ** p < 0.01 and *** p < 0.001, n = 8) reduction in the number of writhes and an increase in swimming endurance time. Stressful conditions changed plasma glucose, cholesterol and triglyceride levels, which were used as markers when evaluating stress in animal models. The level of these markers was nearly brought to normal when pre-treated with flavones and flavonols (10 mg/kg) for fifteen days in experimental animals. These compounds also considerably reduced the levels of lipid peroxidation (TBARS: Thiobarbituric acid reactive substances), which was significant (* p < 0.05, ** p < 0.01 and *** p < 0.001, n = 8) compared to the control group. A significant rise in the level of catalase and SOD (super oxide dismutase) was also observed in the treated groups. Diazepam (2 mg/kg) was used as the standard drug. Additionally, the flavonoids markedly altered the weight of the adrenal glands, spleen and brain in stress-induced mice. The findings of the study suggest that these flavonoids could be used as a remedy for stress and are capable of ameliorating diverse physiological and biochemical alterations associated with stressful conditions. However, further experiments are needed to confirm the observed potentials in other animal models, especially in those with a closer resemblance to humans. Toxicological evaluations are also equally important.

The Role of Potassium Channel Gates in the Electrophysiology of the Human Gastric Smooth Muscle Cell

Background: The cell membrane acts as a filter, allowing ions to enter and leave the cell. Ionic channels are responsible for passing ions. This task is the responsibility of the ion channel gates, and ion transfer generates the action potential. Potassium channels play a prominent role in gastrointestinal smooth muscle cells and slow-wave production. Potassium channels are involved in acid secretion and gastric contraction. Gastric functional problems such as reflux disease and motility disorder are classified as electrophysiological disorders. Objectives: This study aimed to investigate the effect of potassium channel gates on the electrophysiology of the human gastric smooth muscle cells. Methods: Three states were considered for the potassium channels gate (Including physiological state, 50% blockage, and 90% blockage) to investigate the effect of the status of the gates, and a slow-wave diagram was obtained in these three states. Then, the value and the time of action potential were compared at five indicator points (initial potential, maximum spike potential, minimum valley potential, maximum plateau potential, and resting potential) in slow-wave. Results: The results showed that the maximum effect of the activation parameter of the potassium channel gate (τd,Kni) was in 90% blockage compared to the physiological state, so that the maximum spike potential decreases by 2.43%. Also, a 90% blockage in the fast potassium channel gate inactivation parameter (τf,Kfi) increased the maximum spike potential by 12.6% compared to the physiological state, while the minimum valley potential increased by 3%. In addition, the τf,Kfi parameter reduced the time of occurrence of the maximum plateau potential by 7.9%. Conclusions: Potassium channels affect the slow-wave of the human gastric smooth muscle cell in spike, valley, and plateau phases. Using this method and blocking ion channels by pharmacological agents, the effect of ions in different phases of the slow-wave can be investigated. Also, it can help improve the contractile and motility disorders of the smooth muscles of the gastrointestinal tract.

Trade-offs between xylem hydraulic efficiency and mechanical strength in Chinese evergreen and deciduous savanna species.

Evergreen and deciduous species coexist in tropical dry forests and savannas, but differ in physiological mechanisms and life-history strategies. Hydraulic conductivity and mechanical support are two major functions of the xylems of woody plant species related to plant growth and survival. In this study, we measured sapwood-specific hydraulic conductivity (Ks), leaf-specific hydraulic conductivity (KL), modulus of rupture (MOR) and elasticity (MOE), xylem anatomical traits and fiber contents in the xylems of 20 woody species with contrasting leaf phenology (evergreen vs deciduous) in a Chinese savanna. Our results showed that deciduous species had significantly higher Ks and KL but lower MOR and MOE than evergreen species. Evergreen species experienced more negative seasonal minimum water potential (Pmin) than deciduous species during the dry season. Furthermore, we found trade-offs between xylem hydraulic efficiency and mechanical strength across species and within the evergreen and deciduous groups, and these trade-offs were modulated by structural and chemical traits. Both Ks and KL were significantly related to hydraulic weighted vessel diameter (Dh) across all species and within the deciduous group. Both MOR and MOE were significantly related to wood density, neutral detergent fiber and acid detergent fiber across species and within evergreen and deciduous groups. Our findings demonstrated that Chinese evergreen and deciduous savanna species diverged in xylem hydraulic and mechanical functions, reflecting conservative and acquisitive life-history strategies for evergreen and deciduous species, respectively. This study provides new information with which to understand the hydraulic and biomechanical properties and ecological strategies of savanna species in long-term dry-hot environments.

Estimating Volume Loss for Shield-Driven Tunnels Based on the Principle of Minimum Total Potential Energy

Volume loss is an important method to estimate ground movement during tunnelling. However, volume loss is usually estimated by empirical methods, especially for volume loss at the tunnel face, which is a three-dimensional problem. Based on the principle of minimum total potential energy, we proposed a semi-analytical method to predict the volume loss at the tunnel face and ground surface. The proposed method provides a more direct way of estimating volume loss at the tunnel face from an energy point of view. Moreover, a new deformation mechanism was designed to describe the ground movement before the tunnel face. Based on the proposed method, we investigated the influence of the support pressure, tunnel diameter, and tunnel depth on the volume loss at the tunnel face, and other parameters related to surface subsidence. The volume loss at the tunnel face decreased with the increase in the support pressure ratio and the slurry weight. The volume loss at ground surface was generally smaller than the volume loss at the tunnel face due to the soil compression during ground movement. The bigger the tunnel diameter, the bigger the volume loss at the tunnel face. However, the volume loss at ground surface may not increase with the increase in tunnel depth, because of the soil arching effect. Moreover, the deeper the tunnel, the more obvious the influence of the support pressure ratio on volume loss. Similarly, the bigger the tunnel diameter, the more obvious the influence of the slurry weight on the volume loss.

Phytogeographical origin determines Tropical Montane Cloud Forest hydraulic trait composition

Abstract Tropical montane cloud forests (TMCF) have unique climatic conditions, which allow the coexistence of plant lineages with different phytogeographical origins from tropical versus temperate climates. Future climate projections suggest TMCFs will be subjected to increasing drought stress due to fog uplift and higher temperatures, possibly leading to tree mortality and local extinctions, and consequently changes in forest composition and functioning. Characterizing community functional composition, trade‐offs among traits and the drivers of community assembly is of utmost importance to improve our capacity to predict the response of montane plant communities to forecast climate change. Here, we aimed to test whether species from different phytogeographical origins (i.e. tropical – evergreen × deciduous − and temperate) differ in drought vulnerability and how the coexistence of these groups change the hydraulic composition of TMCFs. We used a framework based on measurements of key hydraulic traits (i.e. xylem embolism resistance, hydraulic safety margin, stomata control, turgor loss point, minimum water potential) of 16 dominant species (&gt;70% of the forest basal area) within a TMCF in the Atlantic Rain Forest Domain in southeast Brazil. We used community‐weighted means to model whether removing each species group would change the community hydraulic functional composition. Temperate, tropical deciduous and tropical evergreen groups differ in their hydraulic functioning and these differences explain forest functional composition and taxa dominance. Temperate and tropical deciduous taxa were consistently more vulnerable hydraulically (i.e. lower safety margins and embolism resistance). The coexistence of different phytogeographical lineages is a key determinant of TMCF hydraulic composition. We also used models including phylogeny to evaluate the variation of hydraulic traits across phytogeographical groups, and the results suggest some niche conservatism associated with plant hydraulic functioning. Our results provide evidence of the importance of species phytogeographical origin on TMCF functioning, and niche conservatism in the evolution of hydraulic traits. The higher drought vulnerability observed in temperate group might be a mechanistic explanation for the restriction of temperate taxa distribution to wetter places during past colder and drier climate. Thus, we suggest hydraulic functional traits may be useful to predict future dynamics of TMCFs under changing climatic conditions.

An accurate hyperelasticity‐based plate theory and nonlinear energy‐based micromechanics for impact and shock analyses of compliant particle‐reinforced FG hyperelastic plates

AbstractThe current article is devoted to the nonlinear dynamic and impact response analyses of rectangular incompressible neo‐Hookean hyperelastic plates with uniform/nonuniform transverse distributions of stiff elastic reinforcing particles. The nonlinear finite element governing equations are derived by using the principle of minimum total potential energy and solved by an updating scheme that uses the Runge‐Kutta time integration and penalty methods. The impact energy expressions are written for the integrated plate‐indenter system. The novelties of the article are: (i) realistic modeling the energy absorption of a particle‐reinforced nonlinear hyperelastic matrix based on the volume fractions of the constituent phases instead of using wrong Voigt‐type models or impractical predefined gradation coefficients, (ii) considering non‐uniform distributions of the reinforcing particles, (iii) using a highly accurate asymmetric (all the available theories are symmetric) infinite‐order plate theory, (iv) including the inherent hyperelastic nature of the material in the definition of the parameters of the plate theory, (v) considering the thickness changes of the plate, (vi) including von Karman's kinematic nonlinearity, (vii) analyzing both the dynamic and impact behaviors, (viii) proposing an adaptive algorithm to match the description of the displacement field with the load/stress variations, (ix) updating not only the stiffness but also the mass matrix within the time steps, (x) incorporation of the nonlinear boundary conditions by the penalty method, and (xi) performing time‐dependent analyses instead of the natural frequency analyses. Results reveal the drastic effects of the volume fraction of the reinforcing particles on the dynamic responses and report the impact responses of the FG hyperelastic plates, for the first time.

The quantum vortex states in extended Bose–Hubbard model: effects of lattice geometries, inter-particle interactions and spatial inhomogeneity

We study quantum vortex states of strongly interacting bosons in a two-dimensional rotating optical lattice. The system is modeled by Bose-Hubbard Hamiltonian with rotation. We consider lattices of different geometries, such as square, rectangular and triangular. Using numerical exact diagonalization method we show how the rotation introduces vortex states of different ground-state symmetries and the transition between these states at discrete rotation frequencies. We show how the geometry of the lattice plays crucial role in determining the maximum number of vortex states as well as the general characteristics of these states such as, the average angular momentum $<L_z>$, the current at the perimeter of the lattice, phase winding, the relation between the maximum phase difference, the maximum current and also the saturation of the current between the two neighboring lattice points. The effect of the two- and three-body interactions between the particles, both attractive and repulsive, also depends on the geometry of the lattice as the current flow or the lattice current depends on the interactions. We also consider the effect of the spatial inhomogeneity introduced by the presence of an additional confining harmonic trap potential. It is shown that the curvature of the trap potential and the position of the minimum of the trap potential with respect to the axis of rotation or the center of the lattice have a significant effect on the general characteristics these vortex states.

Machine-learning-guided descriptor selection for predicting corrosion resistance in multi-principal element alloys

More than $270 billion is spent on combatting corrosion annually in the USA alone. As such, we present a machine-learning (ML) approach to down select corrosion-resistant alloys. Our focus is on a non-traditional class of alloys called multi-principal element alloys (MPEAs). Given the vast search space due to the variety of compositions and descriptors to be considered, and based upon existing corrosion data for MPEAs, we demonstrate descriptor optimization to predict corrosion resistance of any given MPEA. Our ML model with descriptor optimization predicts the corrosion resistance of a given MPEA in the presence of an aqueous environment by down selecting two environmental descriptors (pH of the medium and halide concentration), one chemical composition descriptor (atomic % of element with minimum reduction potential), and two atomic descriptors (difference in lattice constant (Delta {{{mathrm{a}}}}) and average reduction potential). Our findings show that, while it is possible to down select corrosion-resistant MPEAs by using ML from a large search space, a larger dataset and higher quality data are needed to accurately predict the corrosion rate of MPEAs. This study shows both the promise and the perils of ML when applied to a complex chemical phenomenon like corrosion of alloys.

An investigation of aero-thermo-elastic flutter and divergence of functionally graded porous skew plates

Aero-thermo-elastic flutter and divergence analyses of functionally graded (FG) porous skew plates subjected to supersonic airflow are investigated in this study. The material properties of skew plates vary across the thickness based on the modified power-law model. Three types of thermal loading as constant, linear and nonlinear temperature distributions in the thickness direction of the plate are considered. Applying the Hamilton’s principle, the coupled partial differential equations of motion and the associated boundary conditions based on the first-order shear deformation theory and linear piston theory are derived in the Cartesian coordinates. Also, the principle of minimum total potential energy and adjacent equilibrium criterion are used to obtain the stability equations. Using a mapping, the partial differential equations of motion and stability equations are converted from Cartesian coordinate system to a skew coordinate. The partial differential equations in the skew coordinate are discretized by generalized differential quadrature method (GDQM) and solved using the state space method. Consequently, the effects of geometrical, mechanical and thermal parameters such as thermal loading types, angle of skew, power-law index, porosity, and boundary conditions on the flutter and divergence boundaries of skew plate are studied in detail.

Stem and leaf xylem of angiosperm trees experiences minimal embolism in temperate forests during two consecutive summers with moderate drought.

Drought events may increase the likelihood that the plant water transport system becomes interrupted by embolism. Yet our knowledge about the temporal frequency of xylem embolism in the field is frequently lacking, as it requires detailed, long-term measurements. We measured xylem embolism resistance and midday xylem water potentials during the consecutive summers of 2019 and 2020 to estimate maximum levels of embolism in leaf and stem xylem of ten temperate angiosperm tree species. We also studied vessel and pit membrane characteristics based on light and electron microscopy to corroborate potential differences in embolism resistance between leaves and stems. Apart from A. pseudoplatanus and Q. petraea, eight species experienced minimum xylem water potentials that were close to or below those required to initiate embolism. Water potentials corresponding to ca. 12% loss of hydraulic conductivity (PLC) could occur in six species, while considerable levels of embolism around 50% PLC were limited to B. pendula and C. avellana. There was a general agreement in embolism resistance between stems and leaves, with leaves being equally or more resistant than stems. Also, xylem embolism resistance was significantly correlated to intervessel pit membrane thickness (TPM ) for stems, but not to vessel diameter and total intervessel pit membrane surface area of a vessel. Our data indicate that low amounts of embolism occur in most species during moderate summer drought, and that considerable levels of embolism are uncommon. Moreover, our experimental and TPM data show that leaf xylem is generally no more vulnerable than stem xylem.

Threshold Voltage and Flat Band Voltage of Normally on Junction Less Field Effect Transistor

Threshold Voltage and Flat band Voltage model of Normally on JLFET is presented in this paper. The threshold voltage is the value of the gate to source voltages at which the depletion width equals to the thickness of the channel. For a normally on JLFET ideally, no current flows above the threshold voltages. Flat band voltage is the value of the gate voltage at which channel is completely neutral. In other word the thickness of depletion layer and accumulation layer is zero at flat band voltage. The model is based on the minimum central and surface potential of the device. The Threshold voltage is determined from the minimum central potential and the flat band voltage is determined by the minimum surface potential. The two models are validated by comparing them with results obtain from TCAD.

Multiview Point Cloud Registration Based on Minimum Potential Energy for Free-Form Blade Measurement

Point cloud registration is an essential step for free-form blade reconstruction in industrial measurement. Nonetheless, measuring defects of the 3-D acquisition system unavoidably result in noisy and incomplete point cloud data, which renders efficient and accurate registration challenging. In this article, we propose a novel global registration method that is based on the minimum potential energy (MPE) method to address these problems. The basic strategy is that the objective function is defined as the MPE optimization function of the physical registration system. The function distributes more weight to the majority of inlier points and less weight to the noise and outliers, which essentially reduces the influence of perturbations in the mathematical formulation. We decompose the solution into a globally optimal approximation procedure and a fine registration process with the trimmed iterative closest point algorithm to boost convergence. The approximation procedure consists of two main steps. First, according to the construction of the force traction operator, we can simply compute the position of the potential energy minimum. Second, to find the MPE point, we propose a new theory that employs two flags to observe the status of the registration procedure. We demonstrate the performance of the proposed algorithm on four types of blades. The proposed method outperforms the other global methods in terms of both accuracy and noise resistance.

Competing on the same stage: Ru-based catalysts modified by basic ligands and organic chlorine salts for acetylene hydrochlorination

The lower the minimum surface electrostatic potential of the ligand, the better the modification effect on Ru-based catalysts. The modification effect of HMTA and DABCO on Ru-based catalysts is greatly improved when they are prepared into organic chlorine salts.

Extraorally proliferating verrucous carcinoma of buccal mucosa mimicking squamous cell carcinoma: A rare case presentation

Verrucous carcinoma (VC) (Ackerman's tumor/Snuff dipper's cancer) is a variant of oral squamous cell carcinoma (SCC) with minimum aggressive potential. The most common sites of involvement in the head-and-neck regions are oral cavity and larynx. VC of the oral cavity is a different clinicopathologic tumor distinguished from the usual SCC because of its local invasiveness, nonmetastasizing behavior, and special clinical appearance, but long-standing cases have shown transformation into SCC. An accurate pathological diagnosis is difficult because of an inadequate tumor sample for the study, and more importantly, a close collaboration is needed between a clinician and a pathologist to achieve the correct diagnosis. In this article, we discuss a case of 42-year-old male with VC of the left buccal mucosa which was proliferating extraorally.