Band Thickness Research Articles

Modelling localised failure in porous reservoir rocks using a continuum model with an embedded localisation band

The localised failure of highly porous rocks usually involves the size-dependent responses governed by the presence of planar bands in the form of compaction bands under high confinements. Deformations inside these bands induced by grain crushing are much higher than the surrounding host rock, making the rock structure inhomogeneous. This post-localisation mechanism is not able to be correctly captured by classical constitutive models for rocks due to the assumption of homogeneous deformation. The inhomogeneous behaviour can be addressed by our mechanism-based constitutive model in this paper, accounting for properties of the mesoscale localisation bands. In this model, the inclination and thickness of compaction bands are taken into account in kinematic enrichments to connect elastic responses outside and inelastic responses based on breakage mechanics theory inside them. The potential of the proposed approach is presented through several numerical examples, using triaxial tests on rocks.

Temperature Dependent Band Gap Correction Model Using Tight-Binding Approach for UTB Device Simulations

In order to accurately determine the electrostatics of Ultra-Thin-Body (UTB) devices, the semi-empirical tight-binding (TB) approach is widely used for calculating the channel thickness dependent band structure of any material at those temperatures where TB parameters are available (generally defined at 0 K and 300 K). In this work, we analyze the variation of band structure for Si, Ge, and GaAs over different channel thicknesses at 0 K and 300 K, and show that the band curvature at the band minima remains unchanged with temperature, while the band gap changes significantly and affects the channel electrostatics. Based on this finding, we propose an approach to simulate the electrostatics of UTB devices, at any temperature between 0 K and 300 K, using the band structure obtained at 0 K, along with a suitable channel thickness and temperature-dependent band gap correction. From the results obtained for the channel charge density, we show good agreement with band structure based simulation results, at 300 K, over a wide range of channel thicknesses, for Si, Ge, and GaAs, while also showing good agreement with TCAD simulation results, at a typical intermediate temperature of 150 K, thus highlighting the accuracy, simplicity and wide applicability of the proposed approach.

Facilitating glaucoma diagnosis with intereye neuroretinal rim asymmetry analysis using spectral-domain optical coherence tomography.

To determine whether intereye asymmetry of a three-dimensional neuroretinal rim parameter, the minimum distance band, is useful in differentiating normal eyes from those with open-angle glaucoma. This is a cross-sectional study of 28 normal subjects and 33 glaucoma subjects. Subjects underwent spectral domain optical coherence tomography imaging of both eyes. From high-density raster scans of the optic nerve head, a custom-designed segmentation algorithm calculated mean minimum distance band neuroretinal rim thickness globally, for four quadrants, and for four sectors. Intereye minimum distance band thickness asymmetry was calculated as the absolute difference in minimum distance band thickness values between the right and left eyes. Increasing global minimum distance band thickness asymmetry was not associated with increasing age or increasing refractive error asymmetry. Glaucoma patients had thinner mean neuroretinal rim thickness values compared to normal patients (209.0 μm vs 306.0 μm [P < 0.001]). Glaucoma subjects had greater intereye thickness asymmetry compared to normal subjects for the global region (51.9 μm vs 17.6 μm [P < 0.001]) as well as for all quadrants and all sectors. For detecting glaucoma, a thickness asymmetry value >28.3 μm in the inferior quadrant yielded the greatest sum of sensitivity (87.9%) and specificity (75.0%). Globally, thickness asymmetry >30.7 μm yielded the greatest sum of sensitivity (66.7%) and specificity (89.3%). This study indicates that intereye neuroretinal rim minimum distance band asymmetry measurements, using high-density spectral domain optical coherence tomography volume scans, may be an objective and quantitative tool for assessing patients suspected of open-angle glaucoma.

Improve the dupilumab therapy evaluation with dermoscopy and high-frequency ultrasound in moderate-to-severe atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory disease. Monoclonal antibody dupilumab was approved to treat moderate-to-severe AD in recent years. An objective assessment of treatment response by skin imaging modality is adjuvant for clinical evaluations. This study aimed to explore the value of dermoscopy and high-frequency ultrasound (HFUS) imaging characteristics in treatment evaluation for moderate-to-severe AD patients treated with dupilumab. Moderate-to-severe AD patients refractory to conventional therapy were enrolled in the study. All patients went through at least a 16-week standardized treatment of dupilumab. Clinical scores (eczema area scoring index [EASI], SCOARD, numerical rating scale of pruritus, dermatology life quality index), dermoscopy, and HFUS examinations were conducted at 0, 2, 4, 8, 12, and 16 weeks of treatment. Erythema, scales, erosion, and pigmentation under dermoscopy were scored, and subepidermal low-echogenic band (SLEB) thickness under HFUS was measured as quantitative indexes. Descriptive analysis and mixed effect linear regression models were used for statistical analysis. Sixteen patients were enrolled in the study and their average age was 45.63±18.18 years. All clinical scores decreased with significant difference after 16-week treatment compared with baseline. All patients achieved EASI 50 (EASI score decreased by 50% or more), and 9/16 patients reached EASI 75 after 16-week treatment. Dermoscopy evaluation of erythema, scales and erosion scores were decreased, and the sign of pigmentation score was increased after treatment. For HFUS, the mean SLEB value was 0.51±0.29 mm and decreased to 0.27±0.15 mm after 16-week treatment (p<0.01). SLEB value decreased linearly with treatment time and correlated with clinical scores. However, SLEB values of two patients were 0.57 and 0.68mm at week 16, respectively, which were higher than the average, and one of the patients showed EASI 75. Dermoscopy and HFUS were able to reveal deeper inflammation response than clinical scores in AD and can be an effective method to evaluate and monitor clinical improvement during dupilumab treatment for AD patients. The preliminary value of imaging methods for predicting the treatment endpoint of dupilumab remains to be verified.

Deformation characteristics of the shear band of silty clay–concrete interface under the influence of freeze–thaw

Direct shear tests of the silty clay–concrete interface under different moisture contents and freeze–thaw (F–T) cycles were conducted to study the mechanical and deformation characteristics of the silty clay–concrete interface under the action of F–T cycles. The change rule of shear band thickness under F–T cycles were analyzed based on particle image velocimetry technology. The microstructure changes of the damaged specimens were observed combined with scanning electron microscopy. Experimental results show that the shear strength of the silty clay–concrete interface is negatively correlated with the F–T cycles and moisture content. The moisture content increases from 12.7% to 20.7%, and the shear strength of the shear band decreases by 7.6%, 7.5%, 7.5%, 12.3%, and 10.5% after 9 F–T cycles, respectively. The shear strength of the shear band decreases obviously after 3 F–T cycles, and tends to be stable after 7 F–T cycles. The successive F–T cycles increases the thickness of the shear band until it stabilizes after 3 F–T cycles. The length and width of cracks inside the specimen increase as the number of F–T cycles rises. The orientation of particles in the shear band is weakened, but the orientation of particles in the shear band is always stronger than that outside the shear band. The change in soil particle and pore content is the most obvious in 3 F–T cycles, and it is the reason for the change in shear band.

Temperature rise in shear bands and its effect on crystallization behavior in bulk metallic glasses

Since the operation of shear band in bulk metallic glasses (BMGs) is accompanied by severe localization in both size and time scales, the measurement of heating and temperature of shear band is extremely difficult. In this paper, temperature rise in the shear bands and its effect on crystallization behavior are investigated in experimental and analytical ways. The released elastic energy, the thickness of shear band and the elapsed time for the energy transfer into the shear band are the key parameters in determining the temperature profile inside and around shear bands. By using the glass transition temperature (Tg) and liquidus temperature (Tliq) in the analytical model, it is possible to determine the shape and the size of hot and liquid zones. It is found that, the size of hot zone is equal to the stable crack growth region and also the size of liquid zone is equal to the vein pattern size on the fracture surface. Since the heating and cooling rates in a hot shear band are extremely high, crystallization cannot appear within the shear band, but is likely to occur around it. In a cold shear band, the heating and cooling in the supercooled liquid region occurs slowly, which is suitable for nucleation and growth of the crystalline phase inside the shear band. However, the crystalline phase appears only on the compressive side of the specimen. These findings provide a new insight for better understanding the deformation behavior of bulk metallic glasses through an analytical method.

Properties of the iliotibial band and their relationships with gait parameters among patients with knee osteoarthritis.

This study aimed to determine the thickness and stiffness of the iliotibial band(ITB) in patients with knee osteoarthritis (KOA) and to identify the gait parameters that are associated with ITB properties. Eighteen female patients with radiographically diagnosed medial KOA and knee pain (age: 69.7 ± 5.9 years, body mass index: 23.0 ± 3.1 kg/m2 ) and 22 age-matched female individuals without knee pain (age: 69.1 ± 7.0 years, body mass index: 21.6 ± 3.6 kg/m2 ) were included. Shear wave elastography images were obtained at the height of the proximal pole of the patella with the participants in the supine position, and the ITB thickness and shear wave velocity, which is a surrogate measure of stiffness, were calculated. In patients with KOA, the knee and hip joint angles and moments during walking were calculated using a motion analysis system. The shear wave velocity was significantly higher in patients with KOA than in asymptomatic adults (11.3 ± 1.0 vs. 10.0 ± 1.8 m/s, respectively; p = 0.010); however, the thickness did not differ between them (2.1 ± 0.3 vs. 2.0 ± 0.3 mm, respectively; p = 0.705). The time-integral value of the knee adduction moment (β = 0.507, p = 0.032) and maximum value of the hip flexion moment (β = 0.498, p = 0.036) were associated with the shear wave velocity. Meanwhile, no parameters were associated with the thickness. The ITB was stiffer in patients with KOA than in asymptomatic adults; such a stiffer ITB was associated with greater knee adduction and hip flexion moments during walking. Clinical Significance: Greater mechanical loading was associated with a stifferITBin patients with KOA.

Evaluation of iliotibial band volume with 3T MRI

Aim: The aim of our study is to evaluate the iliotibial band thickness (ITBT) and volume (ITBV) according to age and gender with 3 T MRI in a healthy Turkish population.&#x0D; Material and Method: In the current study, 150 patients who had knee MRI were retrospectively evaluated. They were divided into the following groups to examine the effects of age: group 1: 18–30 years old; group 2: 31–40 years old; group 3: 41–50 years old; and group 4: 51–60 years old. ITBV measurements were performed on axial T2-weighted knee MR images.&#x0D; Results: The mean age was 42.2±29.6 (range 18-60) years. The mean ITBT was 1.76±0.22 mm and the mean ITBV was 20,24±1,44 mm3 in all patients. There was statistically significant difference in mean iliotibial band thickness and volume between genders (p=0.001; p=0.001). There were no statistically significant differences in mean iliotibial band thickness and volume values between the groups in the one-way ANOVA test (p &gt;0.05). &#x0D; Conclusion: Radiological studies on iliotibial band thickness and band area in healthy individuals are new in the literature. This study is the first radiological study in which the volume of the iliotibial band was measured in healthy individuals and was performed on a 3 tesla MR device. Also, it is the first study that is used artificial intelligence for iliotibial band evaluation and the technic is effective and more rapid according to our experience. ITBV and ITBT are statistically significantly higher in males than females. Most thick ITB was detected between the ages of 31-40. The values of our study, especially ITBT, differ from previous studies and the values are altered in a wide range. Therefore, standardization in the calculation is necessary. This topic is open to future research.

Controlling the lag-time and release kinetics of press-coated tablets using process parameters and tablet geometry

Press-coated tablets are an advantageous technology to achieve delayed releases of active ingredients. They are characterized by a core–shell structure, that makes it possible to tune the lag-time and release kinetics in order to meet the chronotherapeutical goals. Thus, these features are the most important quality attributes to be controlled when designing a press-coated tablet. Many studies have focused on the influence of the formulation on the release attributes. This work aims to study the influence of geometrical and process parameters on the release attributes of press-coated tablets, while keeping a constant formulation. In particular, the variation of compression pressure, layer thickness and band thickness made it possible to vary the lag-time from 1 h to 10 h. These parameters also have an influence on the release kinetics after the lag-time. Indeed, two main opening modes were observed during the dissolution test that correspond to fast or slow release rates. The opening mode obtained depends on the density distribution in the shell, which is directly influenced by the process parameters.

Fast and slow light-induced changes in murine outer retina optical coherence tomography: complementary high spatial resolution functional biomarkers.

Fast (seconds) and slow (minutes to hours) optical coherence tomography (OCT) responses to light stimulation have been developed to probe outer retinal function with higher spatial resolution than the classical full-field electroretinogram (ERG). However, the relationships between functional information revealed by OCT and ERG are largely unexplored. In this study, we directly compared the fast and slow OCT responses with the ERG. Fast responses [i.e. the optoretinogram (ORG)] are dominated by reflectance changes in the outer segment (OS) and the inner segment ellipsoid zone (ISez). The ORG OS response has faster kinetics and a higher light sensitivity than the ISez response, and both differ significantly with ERG parameters. Sildenafil-inhibition of phototransduction reduced the ORG light sensitivity, suggesting a complete phototransduction pathway is needed for ORG responses. Slower OCT responses were dominated by light-induced changes in the external limiting membrane to retinal pigment epithelium (ELM-RPE) thickness and photoreceptor-tip hyporeflective band (HB) magnitudes, with the biggest changes occurring after prolonged light stimulation. Mice with high (129S6/ev) vs. low (C57BL/6J) ATP(adenosine triphosphate) synthesis efficiency show similar fast ORG, but dissimilar slow OCT responses. We propose that the ORG reflects passive physiology, such as water movement from photoreceptors, in response to the photocurrent response (measurable by ERG), whereas the slow OCT responses measure mitochondria-driven physiology in the outer retina, such as dark-provoked water removal from the subretinal space.

Understanding the efficiency of roll lubrication when rolling AD33 aluminium alloy bands in industrial twin mill 175Ч300

This paper describes the results of a study that looked at the effect of contact conditions (including the use of industrial oil I40 (5%) for roll lubrication) on the deformation performance and power draw of a twin cold mill 175&times;300 operated by the machine building site in Dong Nai, Vietnam, when rolling 0.55 mm thick bands made of aluminium alloy AD33. The initial band size is 0.7&times;100&times;2,000 mm. The authors considered reological properties of the aluminium alloy, as well as the roll lubrication environment, to come up with a rational rolling process designed for 0.55&times;100 mm bands made from 0.7&times;100&times;2,000 mm rolled steel. Due to the use of industrial oil I40 (5%) in the mill 175&times;300, the number of passes could be reduced from three to two. The use of industrial oil I40 (5%) in the twin mill 175&times;300 ensured the specified precision and helped reduce the loads. Compared with dry rolling, due to the use of industrial oil I40 (5%), the rolling force could be lowered by 6 kN (8.3%) in the first pass and the power draw &ndash; by 0.025 kW (3.34%). At the same time, the second pass saved 2.96 kN (5.24%) of rolling force and 0,017 kW (3.95%) of power while ensuring the preset band thickness at the mill exit. Compared with dry rolling, when using I40 oil, the rolling force distribution efficiency along the band length rises by 22.7% in the first pass and by 14.64% in the second pass. When using I40 oil (5%), the strain distribution u nevenness along the band length drops by 39.15% &mdash; from 2.35 to 1.43% in the first pass and by 70.08% &mdash; from 3.81 to 1.14% in the second pass. When using I40 oil (5%), the thickness distribution along the length of aluminium band at the mill exit is more even than when the rolls are dry or use water. It also results in a minimized longitudinal thickness variation &delta;h &ndash; i.e. 0.01 mm. These findings helped develop a rational rolling process for AD33 aluminium alloy bands that relies on the use of industrial oil I40 (5%) to lubricate the rolls of an industrial twin mill, while cutting the loads and saving power.

High-frequency ultrasound features in vulvar lichen sclerosus and correlation with histopathology.

Vulvar lichen sclerosus (VLS) is a chronic inflammatory disease initially involving anogenital areas. Noninvasive assessment is essential for precise management in VLS. We aim to analyze high-frequency ultrasound (HFUS) features and correlate HFUS with histopathological changes. Forty patients with histopathologically confirmed VLS lesions were retrospectively identified from August 2020 to September 2021. The clinical manifestations, dermoscopic images as well as both 20 and 50MHz HFUS images were assessed. HFUS assessment included epidermal morphology, hypoechoic dermal band thickness, and hypoechoic dermal band internal echo. We compared HFUS images with histopathology, and Pearson's correlation coefficient was used to assess the relationship between hypoechoic dermal band thickness and histopathological depth. Hypoechoic dermal band was present in 100% (40/40) VLS lesions. There was a significant linear positive correlation between the histopathological depth and corresponding hypoechoic dermal band thickness, with a Pearson correlation coefficient of 0.685 (p<0.001). Besides, 95% (38/40) lesions revealed smooth epidermis, and the internal echo of hypoechoic dermal band was assessed as homogeneous in 60% (24/40) and inhomogeneous in 40% (16/40) lesions. HFUS characteristics, as well as measurable hypoechoic dermal band thickness, may provide valuable information in the precise diagnosis and the treatment monitoring of VLS.

Microcracking behaviors and acoustic emission characteristics of granite subjected to direct shear based on a novel grain-based model

In this study, we numerically examine the microcracking behaviors of Alxa porphyritic granite under direct shear using a novel grain-based model considering particle-scale softening mechanism. Associated acoustic emission (AE) activities were monitored using a moment tensor algorithm, and then the effects of normal stress on the microcracking behaviors and AE characteristics of granite were investigated. The shear fracture systems primarily comprised linked tensile crack arrays, of which the proportion of shear cracks increases with an increase in normal stress. Furthermore, additional intra-grain cracks formed because of the strengthening grain interlocking effect, and the thickness of shear band gradually increased. Moreover, with the normal stress increasing, the decreasing b-value of AE events indicated that the proportion of large-magnitude AE events increased. We reported that the maximum-magnitude AE event in the prepeak stage could be used to identify the crack damage point, which could be considered as a potential failure precursor of granites. The displacement ratio of the peak strength point to crack damage point slightly increased with an increase in normal stress, providing a potential warning indicator for the granite failure. Overall, this study provides certain novel insights into the damage behaviors and failure prediction of granites under direct shear.

Potential of optical frequency domain imaging for differentiation between early and advanced coronary atherosclerosis.

This study evaluated whether optical frequency domain imaging (OFDI) accurately distinguish between fibroatheroma (FA) and pathological intimal thickening (PIT) compared with histopathology. A total of 631 histological cross-sections from 14 autopsy hearts were analyzed for the comparison between OFDI and histological images. Of those, 190 (30%) sections were diagnosed with PIT and 120 (19%) with FA. The OFDI signal attenuation rate was calculated from an exponential. The lipid length was measured longitudinally by detection of sequential OFDI frames within a plaque segment containing lipids. The lipid arc was measured with a protractor centered in the center of the lumen. The fibrous cap thickness was defined as the minimum thickness of the signal rich band overlying PIT and FA. There was no significant difference in the OFDI signal attenuation rate between FA and PIT (3.09 ± 1.04 versus 2.79 ± 1.20, p = 0.13). However, the lipid length was significantly longer, the maximum lipid arc was significantly larger, and the fibrous cap thickness was significantly thinner in FA than in PIT (7.5 [4.3-10.3] mm versus 4.3 [2.7-5.8] mm, p < 0.0001, 125 [101-174]° versus 96 [74-131]°, p < 0.0001, and 220 [167-280] µm versus 260 [190-332] µm, p = 0.019). This study revealed OFDI may have the potential capability for discriminating FA from PIT based on the longitudinal and circumferential extent of lipid plaque, although the OFDI signal attenuation rate was similar between FA and PIT.

Reproducibility of Neuroretinal Rim Measurements Obtained from High-Density Spectral Domain Optical Coherence Tomography Volume Scans.

PurposeTo compare the reproducibility of two-dimensional (2D) peripapillary retinal nerve fiber layer (RNFL) thickness and three-dimensional (3D) neuroretinal rim measurements using spectral domain optical coherence tomography (SDOCT) in normal and glaucoma subjects.MethodsOne eye per subject for 27 normal and 40 glaucoma subjects underwent repeat SDOCT RNFL thickness scans and optic nerve volume scans on the same day. From the volume scan, custom software calculated five neuroretinal rim parameters: 3D minimum distance band (MDB) thickness, 3D MDB area, 3D rim volume, 2D rim area, and 2D rim thickness. Within-subject variance (Sw), coefficient of variation (CV), and intraclass correlation coefficient (ICC) were analyzed.ResultsMDB thickness and RNFL thickness have similar reproducibility among normal and glaucoma subjects (eg, global MDB thickness CVs of 2.4% and 3.6%, and global RNFL thickness CVs of 1.3% and 2.2%; P > 0.05 for both comparisons). Reproducibility of MDB thickness was lower in glaucoma patients for the superior and inferior quadrants compared to normal subjects (CVs of 9.6% versus 3.4% and 6.9% versus 2.7%; P < 0.05, respectively). There were no statistically significant differences between both groups for RNFL thickness in the four quadrants. For both patient groups and for all regions, MDB thickness had the lowest CVs among all five neuroretinal rim parameters (eg, global MDB thickness CVs of 2.4% and 3.6% versus 3.0% and 18.9% for the other four neuroretinal rim parameters).ConclusionGlobal MDB and global RNFL thickness are similarly reproducible among normal and glaucoma subjects, though MDB thickness for the superior and inferior quadrants is less reproducible among glaucoma subjects.

Expression of the Growth Hormone Gene during Early Development of Tiger Shovelnose Catfish (Pseudoplatystoma Fasciatum Linnaeus, 1766)

The early development stage of fish is crucial in fish farming, especially catfish species with cannibal characteristics, such as the Tiger Shovelnose Catfish (Pseudoplatystoma fasciatum Linnaeus 1766). Growth plays an essential role in fish’s life, which is influenced by the mechanism of growth hormone (GH). This study analyzed the level of growth hormone (GH) gene expression at several early developmental stages of Tiger Shovelnose Catfish. Samples were taken from an embryo, three days post hatched (dph) larvae to 60 dph juvenile. Isolation of mRNA was carried from the pituitary gland located at the head of the fish. Gene expression analysis was performed using RT-PCR method that compared GH/b-actin genes from band thickness. The results of the analysis showed the highest expression at 60 dph juvenile. The most significant increase in GH gene expression occurred from the egg to three dph larvae (P &lt; 0.05), then decreased to 20 dph juvenile. The increased phenotypic growth was seen from the increased length and weight at 45 dph juveniles. This indicates the amount of growth hormone released at the juvenile stage of 20 dph, thus triggering rapid growth in the next stage at 45 dph juvenile. Growth hormones can act as growth biomarkers in Tiger Shovelnose Catfish. The novelty of this study was to determine the level of GH gene expression in Pseudoplatystoma fasciatum ornamental fish as the object of research. Suggestions for further research to explore genes related to growth mechanisms through transcriptomic and proteomic technologies.

Microstructural evolution and mechanical properties of a micro-alloyed low-density δ-TRIP steel

Ultrahigh tensile strength over 1200 MPa has not been reported for low-density delta-transformation-induced-plasticity (δ-TRIP) steels. In addition, the trade-off between strength and ductility is still inevitable for those steels. This study fills the gap by controlling morphology and volume fraction of δ-ferrite. A micro-alloyed low-density δ-TRIP steel with a chemical composition of Fe–3Al-0.84Cr-0.94Mn-0.31Mo-1.18Ni-0.31Si-0.25V-0.3C (weight percentage, wt.%) was prepared, and the high Al addition resulted in the reduced density of ∼5% with 7.49 g cm−3 in density. By applying varying heat treatment parameters, three steels with different microstructures, i.e. steels A, B and C were prepared. Microstructural morphologies of the three steels are significantly different. Steel A has a medium volume fraction of 56% for dendritic δ-ferrite with moderate average thickness of 3 μm while steel B contains the highest volume fraction of dendritic δ-ferrite (61%) with the smallest thickness of 1 μm. In contrast, steel C has the lowest volume fraction of dendritic δ-ferrite (32%) with the largest thickness of 4 μm. In addition, the volume fractions of lamellar RA are 14%, 8% and 19% for steels A, B and C, respectively. Steel A has an ultrahigh tensile strength of 1270 MPa, while a good ductility of 17% is retained. However, steel B shows the lower ductility of 14% in spite of the higher tensile strength of 1220 MPa. The thickness and volume fraction of δ-ferrite band influence not only the TRIP effect but also the initiation and propagation of cracks. The main reason for steel B with the lower ductility is associated with its smallest thickness and the highest volume fraction of δ-ferrite among the three steels. In contrast, the utmost strength-ductility product of steel C is attributed to its moderate thickness and the lowest volume fraction of δ-ferrite bands, which can alleviate the local stress concentration at the ferrite/martensite boundaries and leads to the improvement of ductility.

Effects of Wooden Dowel Species, Edge Banding Thickness, and Adhesive Types on Embedded Strength in Particleboard

Composite materials, edge banding, and wooden dowels are used in inner decoration and construction of furniture frames. However, there is little information available concerning the embedded strength of various fasteners and, in particular, dowels in these materials. The aim of this study was to determine the embedded strengths of PVC edge bandings with the thickness of 0.8, 1, and 2 mm, and dowels produced from five different wood species bonded parallel to the surfaces of a melamine coated particleboard (YL-Lam) with polyvinyl acetate (PVAc-D4) or polyurethane (PUR-D4). In accordance with TS 4539 standard, the effect of wooden dowel species, thickness of edge banding, and type of adhesives on embedded strength were determined. Embedded strength values of polyurethane (PUR-D4) were found 10 % higher than the embedded strength values of polyvinyl acetate (PVAc-D4). The highest embedded strength was obtained for beech dowel bonded with polyurethane (PUR-D4) adhesive in the samples with 0.8 mm PVC edge banding (2.004 N/mm2), while the lowest embedded strength was obtained for Scots pine dowel with polyvinyl acetate (PVAc-D4) adhesive in the samples without PVC edge banding (0.826 N/mm2). This value is higher than the predicted value that allows designers to estimate the embedded strength of dowels.

Assessment of Psoriatic Skin Features Using Non-Invasive Imaging Technique

Background: Psoriasis is one of the most commonly recognized dermatological diseases, characterized by distinct structural changes, hyperproliferation and inflammation. The aim of the study was quantitative comparisons of psoriatic skin with skin without psoriatic lesions by non-invasive imaging methods. Methods: 71 patients diagnosed with psoriasis vulgaris underwent non-invasive imaging of skin at the site of the psoriatic lesion and at the site without such lesion. Skin density, epidermis thickness and subepidermal low-echogenic band (SLEB) thickness were measured by high-resolution ultrasound (HFU). Blood perfusion was assessed using laser speckle contrast analysis (LASCA) and skin temperature was measured by thermal imaging camera. Hyperspectral camera was used to obtain spectral reflectance profiles in psoriatic lesion and skin without psoriatic changes. Results: The greatest differences in skin density and epidermal thickness between psoriatic and unchanged skin were observed on the forearms. The skin covered with psoriatic plaques was 80% less dense, and the epidermis in this area was 121% thicker. The greatest thickness of SLEB was observed in the knee area (Me = 0.389 mm). Skin with psoriatic lesions is characterized by a higher temperature (Me = 33.6 vs. Me = 31) and blood perfusion than skin without psoriasis (Me = 98.76 vs. Me = 50.65). Skin without psoriasis shows lower reflectance than psoriatic lesion from 623 nm to 1000 nm; below this value, skin without psoriatic lesion shows higher reflectance. Conclusions: Skin density and epidermis thickness, skin blood perfusion, temperature and reflectance can be useful parameters for monitoring the course of psoriasis and its treatment, especially since the examination of psoriatic skin with proposed methods is non-invasive, quantitative and easy to perform in clinical conditions.

Mechanism of shear strength deterioration of soil-rock mixture after freeze–thaw cycles

The growth and melting of internal ice crystals reorganizing the pore structure and internal skeleton of soil-rock mixture (S-RM), which leads to the deterioration of the S-RM shear strength after freeze–thaw cycles and its strength characteristics after the cycles are different from the normal temperature one. Due to unclear S-RM strength deterioration mechanism after freeze–thaw cycles, stability of S-RM cutting slopes in cold regions cannot be effectively evaluated. In this paper, particle flow code (PFC) simulation as well as direct shear and nuclear magnetic resonance (NMR) tests were carried to study strength degradation behaviors and pore structure changes of S-RMs containing various amounts of rock after freeze–thaw cycles. The results show that the shear strength and internal friction angle of S-RM are no longer positively correlated with the rock content after the cycles, and the strength parameters will decrease at rock contents of above 45%. Based on the simulation test, shear band thickness variation after the cycles was quantitatively evaluated, and an innovative method to obtain the fluctuation value of shear failure surface was proposed. It is found that the change laws of shear band thickness and failure surface fluctuation value with rock content after the cycles are consistent with that of shear strength, and they all reach the maximum value when the rock content is 45%. Fractal theory was introduced for quantitative evaluation of changes in S-RM pore structure after the cycles, and combined with the strength parameter attenuation, the strength deterioration mechanism of S-RM was revealed: The deterioration of shear strength in samples containing low rock content is mainly due to changes in the contact form between particles caused by internal inclusion structure formation after the cycles. The deterioration of S-RM with rock content of 55% and 65% is mainly due to attenuation of the internal skeleton effect caused by the appearance of overhead structures. The internal pores and skeleton structure of the sample with 45% rock content have little change, so the attenuation changes of the strength parameters and the undulation value of the failure surface are minimal.