Cavity Wall Research Articles

Defining the URCOTEBS System as a Unilateral Radiographic–Stochastic Model for the Complementary States (Health/Disease) of the D-Organ and Middle-Ear Mucosa

The middle ear (ME) is a notoriously complicated anatomic structure, geometrically arranged as irregular interlinked spheroidal and polyhedric cavities dug inside the temporal bone (TB). The bony walls of these cavities are radiopaque and form the bony support for the D-Organ that we have previously defined as corresponding to the epithelium covering the Antrum walls (belonging to the central cavities of the middle ear) and the walls of mastoid and petrous cavities (the peripheral cavities of the ME). The aim of the study is to define an exact method for categorizing a Unilateral Radiographic COnformation of the TEmporal Bone in Schuller’s projection (URCOTEBS) under one of the four defined conformations and using it for practical everyday clinical purposes. The conclusion is that a radiograph in Schuller’s projection is a concrete way of storing precise information on the status (health/disease) of the D-Organ and therefore of the ME mucosa. These data is encoded within the image and we aim to decode and translate them into clinical data. The URCOTEBS results in an overlapping projection of all bony cavities that comprise the General Endo-temporal Bony Cavity Complex onto the same plain (film). This characteristic of classical film imaging constitutes an advantage from the multiple CT sections, as far as our proposed approach goes, because the set of stochastic information is found in the whole of the cavities taken as one on the same image, to which the measurement gauges can be easily applied. The decoding must be performed accordingly, and this occurs much faster with conventional radiography. This image of the TB in Schuller’s projection is a mirror that reflects the status of the ME mucosa, and URCOTEBS encodes the physiological state of the D-Organ. The present work gives, through stochastic methods, the key to decoding this information into clinical language. In ascending order of their projection areas (projection of their Variable Geometry Peripheral Endo-temporal Bony Cavity Complex) we can recognize URCOTEBS_d, URCOTEBS_c, URCOTEBS_b, and URCOTEBS_a. The corresponding Greek letter designates the state of disease for each of these conformations: URCOTEBS_δ, URCOTEBS_γ, URCOTEBS_β, URCOTEBS_α, and the capital letters define their state of health: URCOTEBS_D, URCOTEBS_C, URCOTEBS_B, URCOTEBS_A. URCOTEBS_d is the smallest unilateral radiographic conformation of the TB in Schuller’s projection and is, by definition, a radiographic image of the state of disease of the D-Organ. The probability of disease in URCOTEBS_d is 100%. This radiographic system is readily available and clinically usable.

Utilization of Embedded Surface Compliance for Suppression of Deep Cavity Flow Noise

Cavity noise suppression is one of the extensively debated aeroacoustic research problem due to its application over the wide range of mechanical systems. This study presents a scheme of embedding surface compliance in form of elastic panels on cavity walls as a mean to achieve significant tonal noise reduction. A deep cavity of aspect ratio D/L = 0.4 operating at Mach number 0.09 is considered. Using the Direct Aeroacoustic Simulation, the rigid cavity case is investigated to uncover the underlying physical processes driving the aeroacoustic coupling phenomenon between the shear layer and the cavity mode. The analysis suggests that each cavity wall supports a certain coupling-associated activity and therefore provides a platform to modify the shear layer - cavity mode interaction in a tacit way through the well-designed positioning of elastic panels. The accordantly mounted elastic panels are then excited with the flow perturbation energy to significantly reduce the pressure fluctuations magnitude of the cavity mode which strongly affects its synchronization with shear layer and hence presents the possibility of significant noise reduction.

Analysis of Helmholtz resonator wall elasticity effects on the performance of periodic acoustic metamaterial

In this paper, a metamaterial made of a porous layer with embedded periodic Helmholtz resonators is studied and the effects of the resonator wall elasticity on the acoustic attenuation performance of the metamaterial are investigated numerically. The analytical transmission loss results using the parallel transfer matrix method show good agreement with finite element results for the rigid wall case. Elastic materials with different thicknesses are considered for the wall of the neck and the top, lateral and bottom walls of the resonator cavity. It is shown that the transmission loss of the metamaterial degrades when the bottom wall of the resonator cavity is elastic. The elasticity of the bottom wall has a significant impact on the performance of the metamaterial. This analysis will help for better design of acoustic metamaterials with periodic Helmholtz resonators.

Validation of a model on the coupling between circular membrane and Helmholtz resonator

Recently, a model was proposed to describe the resonance characteristics of a modified Helmholtz resonator with a circular membrane fitted to one of the cavity walls. The model is based on two equations of motion: 1) One equation for the transverse wave formed on the membrane and 2) the second for the displacement of the air volume in the port of the Helmholtz resonator. When two equations were solved for the displacement of the membrane as a function of the radius, it was shown that, due to the coupling, the resonance frequencies would vary depending on the parameters of the Helmholtz resonator, which may be observed only for the modes with circular nodal lines. In the current study, the proposed model was further validated in a series of measurements under various conditions, and the results were discussed and compared to the predictions of previous models.

High‐frequency wide‐angle reflection and refraction method for structural engineering ground‐penetrating radar surveys

AbstractElectromagnetic wave velocity in ground‐penetrating radar (GPR) constant offset data can be estimated via the diffraction hyperbola fitting method. This method is applicable when radargrams contain diffraction events (hyperbolic patterns) caused by scatters in the host smaller or equal to the dominant wavelength. An alternative method for velocity estimation, if no intrusive information is available for a direct correlation, requires the collection of multi‐offset data. The method is quite common for broad geophysical applications; however, it seems not to be fully utilized for engineering applications, such as slabs/walls where thickness estimation and depth of the embedded features are critical requirements for structural assessments. This method would also overcome the limitations in velocity calibration in environments with no hyperbolic signal signatures. The aim of this study is to explore multi‐offset high‐frequency GPR applications, specifically the wide‐angle reflection and refraction method, for structural engineering, to understand whether it is feasible, possible limitations, and advantages. Numerical models reproducing reinforced concrete elements and a cavity wall were analysed to understand the wave behaviour and predict the response prior to testing on real cases. The main purpose is to explore how reinforcing bars can affect the velocity spectra derived from semblance analysis and what the response would be in a case of multi‐layered structure with increasing velocity with depth (cavity wall). The comparison with real cases showed that, despite some intrinsic limitations, high‐frequency multi‐offset approach could be part of standard workflow for all those surveys where no other velocity estimation method is feasible.

Numerical computations for convective MHD flow of viscous fluid inside the hexagonal cavity having sinusoidal heated walls

This analysis deals the steady and the incompressible MHD fluid flow by sinusoidal walls of a hexagonal cavity with a cylindrical obstacle at the center. Finite element method (FEM), a numerical modeling method is used to examine the heat transfer and fluid flow controlled by the energy equation, the continuity equation and Navier-Stokes equations, which are converted to dimensionless form through suitable parameterization, which are tackled by finite element method. The temperature distribution and velocity fields are displayed for various parameters which are Richardson number, Hartmann number, Reynolds number, velocities’ amplitudes ratio, temperatures’ amplitudes ratio and phase deviation. This graphical study shows good convergent results of temperature and velocity for variation of involved parameters. At the end, the significant effects of the heat transfer rate are discussed in terms of the Nusselt number.

C conjugate heat transfer simulation of swirl internal cooling on blade leading edge

Abstract Swirl cooling can not only increase the area of the heat exchange wall covered by the coolant, but also improve the average heat transfer intensity and uniformity of the target surface. SST k-ω turbulence model is utilized in the conjugate heat transfer numerical simulation. Based on C3X blades, leading edge swirl cooling structure of the corresponding areas are modified. The flow and heat transfer characteristics of swirl cooling are analyzed at different cross-sections and positions. It is found that there exists an optimal aspect ratio and hole spacing to minimize the temperature gradient on the swirl cavity wall. The swirling motion in the swirl cavity can significantly increase the heat transfer coefficient of the wall surface.

The greater omentum and similar serous formations of testis in male white rats.

The greater omentum of white rats appears, in basic morphological features (in miniature), to be homologous to the greater omentum of humans. We study of the greater omentum reaction to the catgut implant. After implantation of the catgut thread, it turned out that not only the greater omentum, but also serous formations similar to it, related to the testicles, are involved in the covering of the implant. The aim of the study was to study the general plan of the structure and the principles of morphometric analysis of serous formations of testis in white male rats. The experiment involved 15 white male rats of reproductive age, weighing from 284 to 334 grams. It has been established that each testicle of white rats has serous (peritoneal derivatives) formations of two types. One of them is a typical mesentery, with which each testicle is separately fixed to the posterior wall of the pelvic cavity, and the other formation is a free regrowth of a duplication of the serous membrane. It was called the epididymal omentum. According to the algorithm for studying the greater omentum in our previous works, it is noteworthy that the area of the greater omentum is noticeably inferior to the area of the epididymal omentums (F = 0.239; p = 0.006). So, if the average value of the area of the greater omentum is 2766.51 ± 388.12 mm2, then the same indicator of the epididymal omentum reaches 4383.36 ± 793.56 mm2, with their approximately the same thickness (F = 1.35; p = 0.291). It has been established that the greater omentum has two, homeomorphic to it, derivatives of the peritoneum, associated with the epididymis, which were justifiably called epididymal omentums and were fully described in the literature for the first time.

Assessment of different types of bricks in varying wall configurations in an indoor thermal environment for a semi-arid region

This study evaluates the indoor thermal benefits of seven bricks, and their combination with cavity walls, Vertical Greening Systems (VGS), and Expanded Polystyrene (EPS) insulation in a semi-arid Indian climate using EnergyPlus simulations. For walls with VGS and exterior EPS with higher heat capacity, peak summer Operative temperatures (Top) reduced up to 2.3°C, followed by cavity walls and EPS on middle of the wall (up to 1.3°C) compared to their respective bare walls. Interior EPS raised Top by up to 0.7°C. VGS and EPS minimized heat flux fluctuations due to their lower Decrement Factor. VGS exhibited superior indoor thermal comfort, with more occupants satisfied for longer durations compared to exterior EPS. This study suggests that applying VGS or EPS on the exterior (regardless of brick type) is more effective in enhancing indoor thermal comfort during hot days in semi-arid regions .

RADT-13. A BIOLOGIC EQUIVALENT DOSE COMPARISON BETWEEN RADIOSURGERY AND COLLAGEN TILE BRACHYTHERAPY FOR POST-OPERATIVE TREATMENT OF A BRAIN METASTASIS RESECTION CAVITY

Abstract INTRODUCTION Recurrence of a previously irradiated brain metastasis represents a challenging clinical scenario. Repeat radiosurgery results in sub-optimal local control (LC). Two independently published prospective cohort studies demonstrated durable LC in this setting with collagen tile brachytherapy (CTBT), a novel Cesium-131 carrier. Here we compare biologically equivalent dosimetric parameters of CTBT to radiosurgery to understand dose metrics that may underlie durable LC from CTBT. METHODS A patient was selected from the multi-institutional prospective CTBT registry (NCT04427384) with a brain metastasis resection cavity near brainstem. Planning was performed for radiosurgery (30Gy in 5 fractions, BED of 48Gy) and CTBT (Cs-131, activity of 3.5U). To directly compare dosimetric parameters between radiosurgery and CTBT, biologic equivalent doses (BED) were calculated for brainstem(α/β of 3, BED3) and oncologically at-risk tissue(α/β of 10, BED10). TG101 brainstem dose-constraints were referenced, and respective BED were calculated. RESULTS The resection cavity was 4mm away from brainstem and contained 7 CTBT tiles (28 Cs131 seeds). Gradient index (GI) (24Gy BED10 volume/48Gy BED10 volume) was 3.8 for radiosurgery and 2.2 for CTBT. Conformality index (CI) (48Gy BED10 volume/CTV volume) was 1.2 for radiosurgery and 2.6 for CTBT. BED10 to 90% of the cavity wall (2mm rim around the resection cavity) was 49.6Gy for radiosurgery and 92.6Gy for CTBT. BED3 dose limit goals (max dose 31Gy in 5 fractions, BED3 95.1Gy and threshold dose 23Gy in 5 fractions, BED3 of 58.3Gy to 0.5cc) were met for both radiosurgery and CTBT. CONCLUSION BED comparisons demonstrate that CTBT leads to higher CI, lower GI, and higher dose to the cavity wall than radiosurgery while meeting BED3 dose limit goals to an adjacent organ at risk. These dose characteristics might underlie durable LC seen in the recurrent brain metastasis setting, though larger scale analyses are being performed with with clinical outcomes on NCT04427384.

Analysis of the seismic vulnerability and innovative retrofit solutions of cavity brickwork walls

This paper offers the results of an experimental investigation aimed at assessing the seismic vulnerability of a type of cavity wall, with a brief discussion of the advantages of this form of construction. Cavity walls were mainly designed to carry vertical loads and to improve the thermal behaviour of the building envelope: these are made of two single-wythe walls (typically using low-perforated bricks) with a cavity filled with a polystyrene panel. Cavity walls often exhibit poor seismic performance. A total of 12 full-size cavity-wall panels were tested in this experimental programme at the laboratory, by conducting shear and bending tests aimed at studying the in-plane and out-of-plane structural responses under simulated seismic actions. In addition, different retrofit solutions were studied and used to reinforce the cavity-wall panels: this included the traditional method to tie the wall leaves with steel connectors, an innovative method made of GFRP (Glass Fiber Reinforced Polymers) rods, and a mortar coating reinforced with a composite grid, known as FRCM (Fiber Reinforced Cementitious Matrix). It was found that the lateral bending-capacity of the panels reinforced with the GFRP rods and a FRCM coating greatly increased over that of the control unreinforced specimens. The proposed reinforced method was able to provide some seismic resisting capacity to the cavity walls, especially against bending and out-of-plane loading, in a more effective way than the traditional method of steel ties.

Complimentary Staining of Caries Detector Dyes in Primary Teeth with or without the Application of a Dentine Bonding Agent

Background: Caries detector dyes are introduced to aid in identifying infected dentine. Many researchers claim that they are not specific in identifying infected dentine since dyes also stains sound tooth surfaces. The use of a dentine bonding agent could help in avoiding the penetration of caries detector dyes to some extent in less mineralized primary teeth. This study assesses caries detector dyes penetration in primary teeth with or without dentine bonding agent application. Methodology: Ninety primary extracted carious teeth were considered for the study. Teeth were divided in to two groups (45 teeth each group): group I with dye application without dentine bonding agent and group II with dye application after dentine bonding agent; in both groups three different types of dyes were used. All cavity walls and surfaces of samples in group 1 were stained with caries detector dyes for 10 s, subsequently washed with water for another 10 s and finally air-dried. A similar procedure was carried for teeth in group II after the application of a bonding agent on visibly sound tooth surfaces without the use of an etchant. Results: A statistically significant difference between two groups for staining of different tooth surfaces was noted. A Kruskal–Wallis one-way ANOVA revealed a statistically significant difference in stain removal among the different groups either by distilled water or sodium hypochlorite were observed. Conclusion: A dentine bonding agent can help in preventing caries detector dye penetration in noncarious tooth surfaces of deciduous teeth.

Two-dimensional numerical analysis on the rock/bolt interaction considering shear and normal relative displacements

Fully-grouted passive bolts are widely used in underground or surface rock excavations and in particular in stabilizing potentially unstable blocks of rock due to sliding on natural discontinuities. Their operating mechanism is complex, but it is possible to consider two stabilizing forces that each bolt applies to the block of rock. These forces depend on the mechanical parameters governing the bolt-rock interaction, which are difficult to evaluate. In this work, specific numerical analyses have been developed, able of evaluating the bolt-rock interaction (in shear and perpendicular to the interface that separates them) for numerous cases that were obtained by varying the main geometric parameters of the bolt, the mechanical properties of the binder material and rock. Thanks to this complex study, it was possible to describe the variability of the interaction parameters and to define, through graphs, the trend of the stabilization forces as the main geometric and mechanical parameters that can be encountered in practice change. The graphs obtained are a useful tool for the correct design of fully-grouted passive bolts and the stabilization of potentially unstable rock blocks on the walls of underground cavities or on the faces of surface excavations.

Cavity evolution of the high-speed cylinder entering the water under different ice-hole diameter constraints

In this study, experimental research on the oblique water-entry process of the high-speed cylinder under the ice-free condition and three different ice-hole diameter conditions based on the high-speed photography technology is carried out. The experimental repeatability is verified. The influence of the ice-hole constraint on the evolution process of the cavity of the cylinder is investigated by dividing in three stages: the cavity expansion stage, the surface closure stage, and the deep closure stage. Besides, the evolution characteristics of the cavity under four different experimental conditions are studied. Results show that during the cavity expansion stage, the cavity expansion is constrained by the ice-hole. The left side of the cavity near the free surface is curved. With the increase of the ice-hole diameter, the curvature of the left side profile of the cavity gradually decreases. The liquid around the water-entry point impacts the inner wall of the ice-hole to generate a reflective flow. During the surface closure stage, the impact of the reflective flow inhibits the contraction of the right side of the cavity wall, which further induces that the surface closure of the cavity is delayed. Besides, under the influence of smaller ice-hole, the right tail of the cavity wall is impacted by the reflective flow and a local impact collapse occurs. As the diameter of the ice-hole increases, the right tail of the cavity wall is folded but does not collapse significantly, and independent surface closure jet and reflective flow can be observed. During the deep closure stage, under the ice-hole constraint, in addition to the puff-off collapse, it can be found that the shedding collapse is accompanied by the local impact collapse. The occurrence of cavity deep closure of the cylinder is accelerated.

Numerical Study of High-Speed Vertical Water Entry of Hollow Projectiles with Different Aperture Sizes and Velocities

The hollow projectile is a new type of projectile that has complex water entry hydrodynamics characteristics and has attracted significant attention in recent years. As such, it is important to investigate the effects of different entry velocities and aperture diameters on the cavity morphology, cavitation, dynamics, and motion characteristics of hollow projectiles when entering water at high speeds. In this study, four stages of an open cavity, cavity stretching, cavity closure, and cavity contraction in the water entry processes of a hollow projectile at 50–200 m/s and four aperture diameter projectiles at 100 m/s were studied using the volume of fluid (VOF), realizable k-ε turbulence, and Schnerr-Sauer cavitation model. With an increase in the speed, the depth of the cavity closure increases, thereby advancing the closure time. The timing of the surface closure at 50 m/s is clearly different from that at 100–200 m/s. Cavitation is not obvious and is near the cavity wall at 50 m/s, although the entire cavity is almost filled with vapor at 100–200 m/s. The friction resistance has two step points when impacting the water surface and entering the water completely. As the velocity increases or the aperture ratio reduces, the splash is higher, the cavity volume is larger, the cavitation phenomenon is more obvious, the cavity closure time is delayed, and the frictional resistance of the projectile is greater. The results of this study can guide the production and application of hollow projectiles in the future.

A reusable, low-cost model to improve resident confidence in performance of postpartum tubal ligation

Proficiency in postpartum abdominal sterilization is a core objective that residents must acquire during residency as outlined by the Council on Resident Education in Obstetrics and Gynecology. Surgical sterilization remains a popular and effective form of contraception in the United States; however, many women requesting immediate postpartum tubal ligation are unable to have the procedure given institutional barriers and variations in practice. Additionally, increasing use of long-term reversible contraceptives has contributed to declining immediate postpartum sterilization rates, which may ultimately impact an Obstetrics and Gynecology resident’s ability and confidence to perform this procedure. Our goal was to develop a reusable, low-cost model to improve resident familiarity and confidence with postpartum tubal ligation. A 3-dimensional model was developed that represents key anatomic structures encountered during tubal ligation and allows residents to perform all procedure steps. Materials and costs were determined. The model was piloted during scheduled simulation time. Residents evaluated the model’s realism and reported confidence in performing the tubal ligation pre- and post-simulation with a 5-point Likert scale . Four reusable models were created for $21.56 each. All PGY level residents (n=12) successfully performed the procedure with most having performed less than 5 postpartum tubal ligations previously. Resident confidence in performing postpartum tubal ligation improved significantly post-simulation (2.58 vs 3.42/5, p=0.005). Residents strongly agreed that the model replicated the steps (4.83/5), resembled the abdominal wall (4.58/5) and peritoneal cavity (4.73/5), and was similar in difficulty to a live procedure (3.2/5). All residents strongly agreed practicing on this model could improve surgical technique (5/5). This model fills a gap in sterilization simulation and resident training. It is low-cost and easily reproducible, closely resembles the pelvic anatomy, allows for completing the steps of the procedure and can be used for resident education to improve confidence with immediate postpartum sterilization.

Examining the Risk of Summertime Overheating in UK Social Housing Dwellings Retrofitted with Heat Pumps

The UK government has announced its ten-point plan to annually install 600,000 low-carbon heat pumps by 2028. However, there is a lack of evidence showing potential overheating risk in dwellings retrofitted with heat pumps. This paper examines the prevalence and magnitude of summertime overheating across 24 naturally ventilated social housing dwellings retrofitted with ground source heat pumps (GSHPs). The dwellings are located in a socially deprived area in Oxford (UK). The empirical study included longitudinal monitoring of indoor temperatures in the living rooms and bedrooms during the non-heating seasons of 2021 and 2022 (May–September), which included a record-breaking heatwave in July 2022. Indoor temperature and CO2 levels in bedrooms were monitored across a subset of six dwellings alongside the monitoring of window opening state in three bedrooms to understand the effect of natural ventilation in removing excess heat. About 136 thermal comfort surveys were conducted to ascertain the subjective responses of residents. Overheating risk assessment was carried out using CIBSE static and adaptive methods, which revealed that summertime overheating was prevalent across half of the dwellings in the non-heating season of 2022, as compared to 17% overheated dwellings in 2021. Bungalows with upgraded cavity wall insulation and top floor flats facing south and south-west had a propensity to overheat. The variation in indoor temperature and CO2 levels across a small sample also indicated the relationship between overheating and residents’ behaviour. Given that the majority of the dwellings were occupied by retired elderly people with low incomes who are vulnerable to heat and cannot afford active forms of cooling, it is vital to deploy passive design measures, such as appropriate shading devices that are suitable for a heating-dominated climate and enhanced ventilation, as part of home energy retrofits. Implementing reversible heat pumps coupled with solar PVs can provide cooling during heatwaves while delivering low-carbon heat in the winter.

A High-Affinity "Synthavidin" Receptor for Squaraine Dyes.

Strong-binding host-guest pairings in aqueous media have potential as "supramolecular glues" in biomedical techniques, complementing the widely-used (strept)avidin-biotin combination. We have previously found that squaraine dyes are bound very strongly by tetralactam macrocycles possessing anthracenyl units as cavity walls. Here we show that replacing the anthracenes with pentacyclic 5,7,12,14-tetrahydro-5,7,12,14-tetraoxapentacene (TOP) units generates receptors which bind squaraines with increased affinities (around Ka =1010 m-1 ) and improved selectivities. Binding can be followed through changes to squaraine fluorescence and absorbance. The TOP units are easy to prepare and potentially variable, while the TOP-based receptor shows improved photostability, both in itself and in complex with squaraines. The results suggest that this system could prove valuable in the further development of practical "synthavidin" chemistry.

A High‐Affinity “Synthavidin” Receptor for Squaraine Dyes

AbstractStrong‐binding host–guest pairings in aqueous media have potential as “supramolecular glues” in biomedical techniques, complementing the widely‐used (strept)avidin‐biotin combination. We have previously found that squaraine dyes are bound very strongly by tetralactam macrocycles possessing anthracenyl units as cavity walls. Here we show that replacing the anthracenes with pentacyclic 5,7,12,14‐tetrahydro‐5,7,12,14‐tetraoxapentacene (TOP) units generates receptors which bind squaraines with increased affinities (around Ka=1010 m−1) and improved selectivities. Binding can be followed through changes to squaraine fluorescence and absorbance. The TOP units are easy to prepare and potentially variable, while the TOP‐based receptor shows improved photostability, both in itself and in complex with squaraines. The results suggest that this system could prove valuable in the further development of practical “synthavidin” chemistry.

In situ hybridization analysis of odorant receptor expression in the olfactory organ of the pig-nosed turtle Carettochelys insculpta

The turtle olfactory organ consists of upper (UCE) and lower (LCE) chamber epithelium, which send axons to the ventral and dorsal portions of the olfactory bulbs, respectively. Generally, the UCE is associated with glands and contains ciliated olfactory receptor neurons (ORNs), while the LCE is devoid of glands and contains microvillous ORNs. However, the olfactory organ of the pig-nosed turtle Carettochelys insculpta appears to be a single olfactory system morphologically: there are no associated glands; ciliated ORNs are distributed throughout the olfactory organ; and the olfactory bulb is not divided into ventral and dorsal portions. In this study, we analyzed the expression of odorant receptors (ORs), the major olfactory receptors in turtles, in the pig-nosed turtle olfactory organ, via in situ hybridization. Of 690 ORs, 375 were classified as class I and 315 as class II. Some class II ORs were expressed predominantly in the posterior dorsomedial walls of the nasal cavity, while other class II ORs and all class I ORs examined were expressed in the remaining region. These results suggest that the pig-nosed turtle olfactory organ can be divided into two regions according to the expression of ORs.