Specimen Thickness Research Articles

First study of quantitative relationship between electric polarization and electromagnetic interference (EMI) shielding effectiveness of CFRP

This study investigates the electric polarization, including direct current (DC) and alternating current (AC), and electromagnetic interference (EMI) shielding capabilities within the microwave range (2.5–3.9 GHz) of cross-ply continuous carbon fiber-reinforced polymer (CFRP) composites, constructed by stacking prepreg composites. The DC conductivity of CFRP was evaluated using a multimeter, while the AC relative permittivity was measured with electronic test equipment (LCR meter). To describe the relationship between shielding effectiveness and polarization behavior, the EMI shielding of CFRP was assessed using the waveguide method, presenting a quantitative description of this relationship for the first time. Results indicate a decrease in DC conductivity with increasing specimen thickness due to increasing defects. Conversely, AC permittivity increases with specimen thickness, attributed to a rise in charged carriers and associated carrier-atom interactions. Skin depth δ, at a given thickness, follows a trend of initial decrease and subsequent increase with rising frequency; at a given frequency, it increases with decreasing specimen thickness. The interaction between CFRP and radiation is primarily reflective, with the reflection coefficient being much higher than the absorption coefficient across the frequency range, escalating with specimen thickness. Shielding effectiveness (SET) and absorption loss (SEA) display an initial increase followed by a decrease with rising frequency, whereas reflection loss (SER) sees a slight increase. For the smallest thickness, SEA per unit thickness exceeds 3120 dB/m and 7960 dB/m using specimen and carbon thickness, respectively. The absorption loss predominantly arises from the interaction of the electric field with electric dipoles formed by carrier-atom interaction at defects.

Advances in Characterization of Thick Specimens and Time-Resolved <i>In-situ</i> Observation by Modern High Voltage Electron Microscopy

Advances in Characterization of Thick Specimens and Time-Resolved <i>In-situ</i> Observation by Modern High Voltage Electron Microscopy

A novel transition frequency for identification and evaluation of subsurface cracks based on alternating current field measurement technique

Subsurface cracks are more challenging to detect and evaluate compared to surface cracks. This paper introduces a novel transition frequency to identify and evaluate subsurface cracks using alternating current field measurement (ACFM) technique. A theoretical model is proposed to explore current disturbance mechanism for subsurface cracks under different frequencies. A 3D simulation model is established to validate the proposed theoretical model and investigate the effects of crack length, shape and specimen thickness on transition frequency. The ACFM testing system is used to detect subsurface cracks with different burial depths and explore the effect of lift-off on transition frequency. The results demonstrate that, with increasing frequency, the shape of Bx signal for subsurface cracks transitions from a trough to a peak, which can be utilized for identifying subsurface cracks. The burial depth can be accurately assessed by transition frequencies. The transition frequency is hardly affected by crack length, shape and lift-off.

Radiopacity evaluations of the novel calcium-silicate and glass-Ionomer-based materials

Aims: Radiopacity is a crucial property for a liner or base material, and these materials should provide an optimal contrast for detecting secondary caries in radiographic examinations. The purpose of this study was to assess the radiopacity characteristics of four calcium-silicate-based and two glass-ionomer-based materials used as a liner or base in direct or indirect vital pulp therapy.
 Methods: A total of 60 cylindrical-shaped and 1 mm thick specimens were prepared from a calcium-silicate (Biodentine, Septodont), a calcium-silicate (MTA, Angelus), a light-cured resin-modified calcium silicate (TheraCal LC, Bisco), a dual-cured resin-modified calcium silicate (TheraCal PT, Bisco), a glass hybrid glass-ionomer (Equia Forte HT, GC), and a resin-modified glass ionomer (Glass Liner, Wp Dental) material (n=10). Digital radiographic images of the specimens, a molar tooth section with 1 mm thickness, and an aluminum step wedge were obtained by a digital radiography system (Heliodent Plus, 
 Dentsply Sirona) with 60 kV voltage, 7 mA current, and 0.25 seconds exposure time. The mean gray values (MGV) of digital images were determined using the ImageJ software program (National Institute of Health, Bethesda, MD, USA). Kruskal-Wallis and Mann-Whitney tests (pBiodentine>Equia Forte HT>Theracal PT>Theracal LC>Glass Liner, respectively. All the tested liner or base materials exhibited significantly greater radiopacity values when compared to those of dentin (p

Validated assessment of power plant components with flaws and defects operating under long-term creep and isothermal creep-fatigue loading

An extensive database of frequently used heat-resistant steels 1 %Cr, 9–10 %Cr and 12 %Cr steels at application-typical temperatures was evaluated using the Nikbin-Smith-Webster model. Influencing factors, such as the initial plasticization and the specimen thickness, were investigated in the evaluation of the fracture mechanics material characteristic values. A thickness influencing factor fB for crack initiation is proposed, which improves the crack initiation estimation using the NSW model and reduces its over-conservatism notably. It could be shown that the crack initiation and especially the crack growth under creep loading can be described with sufficient accuracy by the modification of the NSW model. The limitation in the application of the C*-parameter could also be shown and explained by the Two-Criteria-Diagram (2CD). It should be applied to crack geometries with predominant crack tip damage. The 2CD is shown as preferred method for a more precise, material-related understanding and assessment of the crack initiation process.Based on the recalculation of fracture mechanics tests on CT und DENT specimens, the analytical approaches for the description of crack initiation and growth under creep and isothermal creep-fatigue loading could be validated in the long-term range by comparison with the experimental results up to 100,000 h.Finally, the transferability of these approaches from CT und DENT specimens to large components was investigated by calculating cracked components under practical creep and isothermal creep fatigue loading using these methods. It has been shown that the load level and the duration of holding time are decisive for the crack initiation and the crack growth under isothermal creep-fatigue loading. In the case of high stress and shorter holding times, the damage is predominantly influenced by fatigue. With lower stress and longer holding times, creep plays a more important role.

Corrosion resistance of hybrid plasma electrolytic oxidation coatings on AZ31B magnesium alloy in simulated body fluid

This study examines the effects of a hydroxyapatite/anatase TiO2/CeO2 coating on the corrosion of AZ31B magnesium alloy in a simulated body fluid. Plasma electrolytic oxidation (PEO) is used to create the coating, and the surface properties are analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). Contact angle measurements adapted to compare the uncoated substrate (144.74 ± 2.08°) with the coated substrates, which exhibit contact angles of (107.92 ± 2.16°), (95.88 ± 2.06°) and (66.05 ± 2.09°) for the respective coating durations. Increasing the thickness of the coating improves its corrosion resistance. Specifically, a 6-minute PEO coating significantly increases the thickness and provides better protection against corrosion for the AZ31B magnesium alloy. Cross-sectional scans of the coated samples revealed an increase in specimen thickness from 32.92 μm to77.17 μm. Potentiodynamic polarisation tests in a simulated body fluid reveal that the 6-minute coated sample shows the highest corrosion resistance, with the lowest corrosion current density (1.9037 × 10-06) compared to other coatings, indicating strong protection against corrosion. This research proposes a novel method to enhance the corrosion resistance of PEO coatings on magnesium alloys by depositing a thicker layer of hydroxyapatite, anatase TiO2 and CeO2. This approach results in a stronger and more effective protective system against corrosion.

An improved analysis of small punch deformation for evaluating tensile properties

Small punch (SP) method is a promising technique for evaluating tensile properties using small volumes of test material, yet its applicability is bound by large errors in estimation of tensile yield strength (YS) using the yield force (FY) determined by the existing two tangent, offset or bilinear function fitting methods. In this study, a yield force (FY) based on the occurrence of yielding across the specimen thickness is identified through finite element analysis and a methodology is formulated for determination of FY from experimental data, supported with acoustic emission (AE) technique. The YS-FY correlation for various structural steels, Inconel and Aluminium exhibit excellent linearity and standard errors within ±7 %. Based on the onset of plastic instability in SP deformation at an inflection point (Fs, us) of force-deflection curve, the specimen deflection us is shown to correlate with tensile uniform strain better than parameter um (deflection at peak load). The tensile properties of neutron irradiated SS 316 evaluated from SP tests using the methodologies and SP-tensile correlations formulated in this work, are found to be within 6–8 % of the uniaxial tensile test results.

Research on the influence of parameters on the fracture performance of the large stone asphalt mixture based on the semi-circular bending test

Pavement failure is a main type of road damage. To investigate the fracture performance of asphalt mixtures with large aggregates, this study utilized the semi-circular bending test to compare the specimens of LSAM-30 (the large stone asphalt mixture) and AC-13 (the fine aggregate asphalt mixture). The research focuses on examining the effects of specimen thickness, notch length, loading rate, and test temperature on the fracture performance. In the assessment of the experimental outcomes, this study employs fracture energy, J-integral, BCI, and CRI as parameters for comparison. The findings demonstrate that under the same conditions, the large stone asphalt mixture exhibits higher peak load, greater fracture energy, higher BCI and CRI values, as well as better J-integral fracture toughness in comparison to the fine aggregate asphalt mixture. At 20°C, the crack path in the large stone asphalt mixture (LSAM) circumvented the large aggregates and thus presented to be bent and long, while the crack in the fine aggregate asphalt mixture was shorter and straighter. The longer and more curved crack path in the LSAM consumed greater energy, resulting in better fracture resistance. At 0°C, the cracks in both asphalt mixtures were linear, but the large aggregate mixture required a stronger load to damage the larger aggregates. Therefore, the LSAM demonstrates a slightly better fracture resistance at low temperatures. In conclusion, the higher peak load, fracture energy, BCI, and CRI of the LSAM indicate a superior fracture performance. The longer and more curved crack path implies greater energy consumption during the fracture. As a result, the LSAM exhibits better fracture performance and resistance to pavement failure compared with the fine aggregate asphalt mixture.

Study on physical and mechanical properties of cement asphalt emulsified mortar under track slab

PurposeDuring the construction process of the China Railway Track System (CRTS) I type filling layer, the nonwoven fabric bags have been used as grouting templates for cement asphalt (CA) emulsified mortar. The porous structure of nonwoven fabrics endowed the templates with breathability and water permeability. The standard requires that the volume expansion rate of CA mortar must be controlled within 1%–3%, which can generate expansion pressure to ensure that the cavities under track slabs are filled fully. However, the expansion pressure caused some of the water to seep out from the periphery of the filling bag, and it would affect the actual mix proportion of CA mortar. The differences in physical and mechanical properties between the CA mortar under track slabs and the CA mortar formed in the laboratory were studied in this paper. The relevant results could provide important methods for the research of filling layer materials for CRTS I type and other types of ballastless tracks in China.Design/methodology/approachDuring the inspection of filling layer, the samples of CA mortar from different working conditions and raw materials were taken by uncovering the track slabs and drilling cores. The physical and mechanical properties of CA mortar under the filling layer of the slab were systematically analyzed by testing the electrical flux, compressive strength and density of mortar in different parts of the filling layer.FindingsIn this paper, the electric flux, the physical properties and mechanical properties of different parts of CA mortar under the track slab were investigated. The results showed that the density, electric flux and compressive strength of CA mortar were affected by the composition of raw materials for dry powders and different parts of the filling layer. In addition, the electrical flux of CA mortar gradually decreased within 90 days’ age. The electrical flux of samples with the thickness of 54 mm was lower than 500 C. Therefore, the impermeability and durability of CA mortar could be improved by increasing the thickness of filling layer. Besides, the results showed that the compressive strength of CA mortar increased, while the density and electric flux decreased gradually, with the prolongation of hardening time.Originality/valueDuring 90 days' age, the electrical flux of the CA mortar gradually decreased with the increase of specimen thickness and the electrical flux of the specimens with the thickness of 54 mm was lower than 500 C. The impermeability and durability of the CA mortar could be improved by increasing the thickness of filling layer. The proposed method can provide reference for the further development and improvement of CRTS I and CRTS II type ballastless track in China.

Developing Representative Test Specimen Conditions for Rutting Mechanical Test Methods of Airfield Pavements

Developing Representative Test Specimen Conditions for Rutting Mechanical Test Methods of Airfield Pavements

Effect of Printing Layer Thickness on Optical Properties and Surface Roughness of 3D-Printed Resins: An In Vitro Study.

To investigate the impact of printing layer thickness on the optical properties and surface roughness of various 3D-printed resins manufactured by digital light processing (DLP) and indicated for provisional and definitive restorations. A total of 240 specimens from four different 3D-printing resins-VarseoSmile Crown Plus (Bego; VS), Crowntec (Saremco Dental; CR), GC Temp PRINT (GC Dental; TG), and NextDent C&B MFH (NextDent; ND)-were divided into four groups (n = 60 per group). Each group was further divided into three subgroups (n = 20) according to printing layer thickness (25, 50, and 100 μm). All specimens were subjected to thermocycling with coffee before measurements were taken with a spectroradiometer to calculate color differences. The Kubelka-Munk (K-M) absorption (K) and scattering coefficients (S), translucency parameters (TP), and surface roughness (Ra) values were calculated for each printing layer thickness and compared with those of the 2M2 shade tab (target). The data were analyzed using Mann-Whitney U test, the variance accounted for (VAF) coefficient by Cauchy-Schwarz, and post hoc comparisons using Tukey test (α ≤ .05). S (79% ≤ VAF ≤ 100%) and K (40.45% ≤ VAF ≤ 100%) spectral distribution depended on the wavelength. A 25-μm layer thickness resulted in no significant differences from the 2M2 shade for S (P > .230) and K (P > .200). VS showed significantly different S (P = .004) and K (P = .003) values from those of the shade tab with 50-μm layering thickness, whereas other materials did not show significant differences from the 2M2 shade for S (P > .280) and K (P > .301). The 100-μm layer thickness specimens had significantly different S and K values compared to the 2M2 shade tab (P < .004). TP values of resins with 100-μm layer thickness were significantly lower than resins in 25- and 50-μm layer thicknesses (P < .001). The Ra values of resins increased significantly with 100-μm layer thickness (P ≤ .001). All tested materials, except for VS, showed color properties similar to the target shade when 25- and 50-μm printing layer thicknesses were used. The translucency of resins tended toward an inverse relationship with printing layer thickness. The surface roughness of resins increased significantly with 100-μm layer thickness. However, all resins with a printing thickness of 25 μm showed better color properties and surface roughness.

The combined effects of a heterogeneous porosity distribution and stress gradient on the high cycle fatigue behavior of high pressure die cast AlSi9Cu3

In order to expand the number of possible applications of High Pressure Die Cast (HPDC) components using the AlSi9Cu3 alloy, the automotive industry is giving greater attention to the fatigue design of components produce by this process-material combination. The process is well known for introducing a heterogeneous distribution of casting defects. This study explores the impact of the heterogeneous porosity distribution and stress gradients on the high cycle fatigue behavior of HPDC AlSi9Cu3 components. Fatigue tests under fully-reversed tension–compression and fully-reversed bending loads are used to investigate the influence of porosity and stress gradients on the fatigue behavior, by machining different specimen thicknesses. The results demonstrate that stress gradients and the heterogeneous porosity distribution determine the material’s fatigue response, including both the fatigue strength and crack initiation mechanisms. The Murakami parameter and local stress level at the critical defect make it possible to interpret the gradient effects. The nature of the entrapped gas in internal defects may influence the in-bulk crack propagation behavior. The comparison of fracture mechanics models (El Haddad, Murakami, Kitagawa-Takahashi) make it possible to highlight the link between the El Haddad’s parameter to parameters that are more microstructurally based.

Impact of filler and gelling catalyst/agent on properties of flexible polyurethane foam

AbstractIn this study, the physiomechanical properties of carboxymethylcellulose sodium salt (Na‐CMC salt) filler‐loaded foam and its impact on the wicking capacity of the foam were investigated in juxtaposition with the increasing tin concentration. According to the study's findings, standard unfilled foam demonstrated no wicking at all, while flexible PU foam filled with Na‐CMC salt, even with low porosity and subpar mechanical traits, displayed wicking heights of 4 mm, 3.4 mm, and 2.8 mm in test specimens of thicknesses of 6 mm, 8 mm, and 10 mm. Moreover, filled foam with a higher porosity level exhibited significantly better wicking heights of 11.4 mm, 10.8 mm, and 8.2 mm. The inclusion of CMC filler in the PU foam matrix is the reason for enhanced wicking property in foam. The sample thickness and wicking height trends are consistent among all foams; as foam sample thickness increases, wicking height progressively falls. The correlation between the foam's porosity value and the number of closed cell windows is confirmed by stereomicroscopy and the porosity values. According to this study, the infused filler's characteristics have a greater influence on the foam's wicking capacity than the foam's porosity. This study contributes significant insights into ongoing initiatives to enhance user experience, well‐being, and hygiene through innovative and meticulously designed new developed mattress foam using Na‐CMC as a filler.Highlights Co‐relation between concentration of tin and infused filler on wicking property. Standard unfilled foam demonstrated no wicking at all. Na‐CMC salt filled foam displayed wicking heights. After 15% increase in tin level, mechanical properties of foam degrade. Wicking depends on nature of infused filler and the foam's porosity.

Differential phase contrast (DPC) mapping electric fields: Optimising experimental conditions.

DPC in Scanning Transmission Electron Microscopy (STEM) is a valuable method for mapping the electric fields in semiconductor materials. However, optimising the experimental conditions can be challenging. In this paper, we test and compare critical experimental parameters, including the convergence angle, camera length, acceleration voltage, sample configuration, and orientation using a four-quadrant segmented detector and a Si specimen containing layers of different As concentrations. The DPC measurements show a roughly linear correlation with the estimated electric fields, until the field gets close to the detection limitation, which is ∼0.5mV/nm with a sample thickness of ∼145nm. These results can help inform which technique to use for different user cases: When the electric field at a planar junction is above ∼0.5mV/nm, DPC with a segmented detector is practical for electric field mapping. With a planar junction, the DPC signal-to-noise ratio can be increased by increasing the specimen thickness. However, for semiconductor devices with electric fields smaller than ∼0.5mV/nm, or for devices containing curved junctions, DPC is unreliable and techniques with higher sensitivity will need to be explored, such as 4D STEM using a pixelated detector.

Improvement of the Cracking Moment-Based Asphalt Mixture Splitting Test Method and Splitting Strength Research

The asphalt mixture splitting test is one of the most important methods for measuring asphalt’s tensile properties. To characterize the limitations of the traditional splitting test and the influence of the specimen size and loading conditions on the accuracy of the test, the factors affecting the strength of the splitting test were analyzed to reveal the splitting failure state and establish a unified representation model between the splitting and direct tensile tests. Initially, the moment of specimen cracking was taken as a key indicator, combined with image processing technology, to establish a set of criteria to judge the splitting test. Subsequently, standardized splitting tests were conducted and compared to tests of different specimen sizes and loading methods. Based on the octahedral strength theory, the stress points before and after the improved test were compared to the existing failure criteria. Direct tensile and splitting tests were conducted at different rates, and a unified strength–rate function model was established, realizing the unified representation of direct tensile and splitting tests. The research results indicate that the standardized splitting test is prone to the phenomenon wherein the specimen end face cracks before the center, affecting the accuracy of the test and potentially leading to redundant material strength evaluations. Using a loading method with a “35 mm specimen thickness” and a “0.3 mm rubber gasket + 12.7 mm arc-shaped batten” can essentially achieve the test hypothesis of “cracking at the center first”, resulting in less discrete outcomes and closer alignment to the three-dimensional stress failure state. The tensile and splitting strengths are both power function relationships with the rate as the independent variable, establishing a unified function model of the tensile and failure strengths. The research provides a more reliable testing method and calculation model for asphalt pavement structure design, and it also provides an effective basis for the improvement of splitting tests on materials such as concrete and rock.

Analysis of the Rotation Bending Test Method and Characterization of Unidirectional Carbon Fiber-Reinforced Polycarbonate Tapes at Processing Temperatures.

Bending is one of the dominant material deformation mechanisms that occurs during the forming process of unidirectional (UD) thermoplastic tapes. Experimental characterization of the bending behavior at processing temperatures is crucial to obtaining close-to-reality data sets for process analysis or material modeling for process simulation. The main purpose of this study is to characterize to a high degree of accuracy the temperature-dependent bending behavior of single and multi-ply specimens of carbon fiber-reinforced polycarbonate (PC/CF) UD tapes at processing temperatures, which implies a molten state of the thermoplastic matrix. The application of the rotation bending test using a customized fixture may come with systematic deviations in the measured moment that result from a pivot offset or an effective clearance that is unknown under realistic test conditions. The present research analyzes these effects with analytical methods, experimental investigations, and simulations using a finite element model. In this context, a compensation method for the toe-in effect is evaluated. With this approach, we were able to obtain reliable data and characterize the bending resistance within the desired processing window. The data reveal a major drop in bending resistance between 200 °C and 250 °C and a less significant decrease between 250 °C and 300 °C. Analysis of the thickness-normalized bending resistances indicates a non-linear relationship between specimen thickness and measured moment but an increasing shear-dominated characteristic at higher temperatures.

The Tensile, Thermal and Flame-Retardant Properties of Polyetherimide and Polyetherketoneketone Processed via Fused Filament Fabrication.

Polymer materials are increasingly widely used in high-fire-risk applications, such as aviation interior components. This study aimed to compare the tensile, thermal, and flame-retardant properties of test samples made from ultra-performance materials, polyetherimide (PEI) and polyetherketoneketone (PEKK), using the fused filament fabrication process (FFF). The tensile tests were performed for these materials at different raster angles (0, 45, and 90°). The thermomechanical tests were done in the axial, perpendicular, and through-thickness directions to the extruded filaments. The impact of printing parameters on the flame retardancy of 3D-printed samples was investigated in vertical burn tests with varying specimen thicknesses and printing directions. Experimentally, it was testified that PEKK had better isotropic behaviour than PEI for mechanical performance, thermal expansion, and fire-resistant properties, which are essential in fabricating intricately shaped products.

Experiment Study on the Mechanical Behavior and Acoustic Emission Response of Thick and Hard Sandstone Roof in Xinjiang Mining Area

One of the primary threats to coal mine safety production is the sudden extensive fracturing and collapse of thick and hard roof strata. A range of uniaxial compression experiments with acoustic emission (AE) monitoring was performed for studying the mechanical properties and crack evolution of thick and hard roof sandstone specimens. AE temporal response analysis revealed that the damage process of thick and hard roof sandstone specimens exhibited distinct stages. Additionally, AE event localization indicated that microcracks within the thick and hard roof sandstone specimens propagated from the ends to the middle of the specimens during the loading process, eventually leading to severe failure. The b-value analysis demonstrated that during the early loading stage, the scale of internal microcracks within the thick and hard roof sandstone specimens gradually decreased with the optimization of the load-bearing structure. In the later loading stage, the scale of microcracks increased with the deterioration of the load-bearing structure. Furthermore, RA–AF analysis revealed that the specimens experienced combined tensile–shear failure, primarily dominated by tensile failure throughout. The AE characteristics observed during the deformation of thick and hard sandstone can provide references for the monitoring of roof stability and early warning of potential disasters in thick and hard sandstone conditions.

Evaluation of creep properties considering the friction effect of the small punch test

In contrast to the Uniaxial Creep Test (UCT), where each stress produces a corresponding strain, the Small Punch Creep Test (SPCT) generates displacement in response to applied loads. Therefore, for the direct application of SPCT in creep damage assessment, it becomes imperative to convert the displacement and load data into the strain and stress parameters observed in the UCT. Unlike the UCT, which applies the load directly to the specimen, the SPCT indirectly imposes the load on the specimen through a punch ball. This divergence in loading methods introduces friction between the specimen and the punch ball during the SPCT. This study delves into the analysis of the friction coefficient between the specimen and punch ball using the Finite Element Method (FEM). Additionally, we explore the relationship between the specimen's minimum thickness and the friction coefficient. In conclusion, we propose a correlation between the creep properties of the two test methods, with the objective of accurately capturing the influence of friction between the specimen and punch ball in the SPCT.

Improved intraoperative identification of close margins in oral squamous cell carcinoma resections using a dual aperture fluorescence ratio approach: first in-human results.

Surgical excision is the main treatment for solid tumors in oral squamous cell carcinomas, where wide local excision (achieving a healthy tissue margin of around the excised tumor) is the goal as it results in reduced local recurrence rates and improved overall survival. No clinical methods are available to assess the complete surgical margin intraoperatively while the patient is still on the operating table; and while recent intraoperative back-bench fluorescence-guided surgery approaches have shown promise for detecting "positive" inadequate margins (), they have had limited success in the detection of "close" inadequate margins (1 to 5mm). Here, a dual aperture fluorescence ratio (dAFR) approach was evaluated as a means of improving detection of close margins. The approach was evaluated on surgical specimens from patients who were administered a tumor-specific fluorescent imaging agent (cetuximab-800CW) prior to surgery. The dAFR approach was compared directly against standard wide-field fluorescence imaging and pathology measurements of margin thickness in specimens from three patients and a total of 12 margin locations (1 positive, 5 close, and 6 clear margins). The area under the receiver operating characteristic curve, representing the ability to detect close compared to clear margins () was found to be 1.0 and 0.57 for dAFR and sAF, respectively. Improvements in dAFR were found to be statistically significant (). These results provide evidence that the dAFR approach potentially improves detection of close surgical margins.