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Scientific Reports Aug 2023To explore how the thickness of the femoral lateral wall influences the effectiveness of internal fixation systems used to treat intertrochanteric fractures. CT images...
To explore how the thickness of the femoral lateral wall influences the effectiveness of internal fixation systems used to treat intertrochanteric fractures. CT images of the pelvis and femur of a male adult were used to construct an intertrochanteric fracture model (AO/OTA 31-A2) with various thicknesses of the femoral lateral wall (FLW). Four finite element (FE) models were created with the lateral femoral walls being 10 mm, 20 mm, 30 mm, and 40 mm thick. The fracture models were fixed with a dynamic hip screw (DHS), a proximal femoral nail anti-rotation (PFNA), and a proximal femoral locking compression plate (P-FLCP). A simulated vertical load was applied to the femoral head. The stress and displacement of the implant and femur in each model were recorded for comparison. The FE analysis of the intertrochanteric fracture models showed that the PFNA system could provide better stability than the DHS and P-FLCP with the same thickness of FLW. The FLW provided buttress support to the femoral head and neck when using a DHS and PFNA, and the buttress strength was proportional to the thickness of FLW. The maximum stress in the DHS model was recorded on the DHS plate which accommodated the lag screw. For the PFNA model, the maximum stress appeared at the connection between the nail and blade. In the P-FLCP model, the maximum stresses were highly concentrated at the connection between the cephalic nails and the proximal plate. The thickness of the femoral lateral wall should be considered an important factor when selecting a suitable internal fixation system for intertrochanteric fractures. Based on the FE analysis, intramedullary fixation, such as PFNA, experiences lower stress levels and a moderate displacement in comparison to DHS and P-FCLP when used to treat intertrochanteric fractures.
Topics: Male; Humans; Treatment Outcome; Finite Element Analysis; Bone Nails; Fracture Fixation, Intramedullary; Hip Fractures; Femur; Retrospective Studies
PubMed: 37542169
DOI: 10.1038/s41598-023-39879-9 -
ACS Omega Dec 2021The objective of this study is to solve the shortcomings of the current transparent bamboo veneer with a small thickness and low light transmittance by means of...
The objective of this study is to solve the shortcomings of the current transparent bamboo veneer with a small thickness and low light transmittance by means of lamination. The delignified bamboo templates were vacuum impregnated with an epoxy resin, and the impregnated bamboo templates were laminated with the same radial texture using the viscosity of the epoxy resin to obtain multilayer transparent bamboo (MLTB). The multilayer stacking method can greatly improve the optical and mechanical properties of transparent bamboo. The transparent bamboo with a thickness of 1.2 mm and the delignified bamboo with a volume fraction of 44.8% prepared by multilayer stacking exhibited an improved total optical transmissivity of up to 78.6%, while the highest transmittance of bamboo (0.9 mm thick) without multilayer stacking treatment was only 10.4%. Compared with the single-layer transparent bamboo with a thickness of 2.1 mm, the maximum tensile strength of the seven-layer transparent bamboo was 4 times that of the single-layer transparent bamboo. Therefore, MLTB can compensate to a certain extent for the low light transmission and poor mechanical properties of single-layer transparent bamboo. Overall, MLTB shows a richer and more layered texture, which has more esthetic value. It is a kind of natural transparent material with good light transmittance and excellent mechanical properties, which has a good development prospect as a structural material in the fields of construction, household, and electronic products.
PubMed: 34926923
DOI: 10.1021/acsomega.1c05014 -
Ophthalmology Science Sep 2023To investigate the relationship between retinal traction force and impairment of the inner retinal layer in patients with epiretinal membrane (ERM).
PURPOSE
To investigate the relationship between retinal traction force and impairment of the inner retinal layer in patients with epiretinal membrane (ERM).
DESIGN
Nonrandomized, retrospective consecutive case series.
PARTICIPANTS
Two hundred nine eyes of 201 patients with idiopathic ERM who underwent vitrectomy for idiopathic ERM were enrolled.
METHODS
Retinal folds caused by ERM were visualized using en face OCT, and the maximum depth of retinal folds within the parafovea (MDRF) was measured. Focal macular electroretinogram (ERG) was used to measure the amplitude and implicit time of each component for the ERM eyes and the normal fellow eyes. B-scan OCT images were used to measure the thicknesses of the inner nuclear layer (INL) and outer nuclear layer (ONL) + outer plexiform layer (OPL). Expression of α-smooth muscle actin (α-SMA) in surgically removed ERM specimens was quantified by reverse-transcription polymerase chain reaction.
MAIN OUTCOME MEASURES
We analyzed the relationship between MDRF and the relative amplitudes of focal macular ERG (affected eye/fellow eye), the relationships between MDRF and the mean INL thickness and ONL+OPL thickness, comparison of INL thickness and ONL+OPL thickness for each area when cases were classified according to MDRF localization in the ETDRS chart, and the relationship between MDRF and the relative expression of α-SMA in the ERM specimens.
RESULTS
The MDRF significantly correlated with the relative amplitudes (affected eye/fellow eye) of b-waves and oscillatory potentials (r = -0.657, = 0.015; r = -0.569, = 0.042, respectively) and the mean INL thickness and ONL+OPL thickness (r = 0.604, < 0.001; r = 0.210, = 0.007, respectively). However, only the INL thickness progression rate was significantly correlated with the MDRF progression rate (r = 0.770, < 0.001). On case stratification by localization of MDRF based on the ETDRS chart, in regions other than temporal regions, the INL thickness was significantly greater in regions with MDRF than in other regions. The MDRF significantly correlated with α-SMA expression in the ERM specimens (r = 0.555, = 0.009).
CONCLUSIONS
The findings suggest that ERM impairs the inner retinal layer in a traction force-dependent manner.
FINANCIAL DISCLOSURES
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
PubMed: 37214764
DOI: 10.1016/j.xops.2023.100312 -
Annual International Conference of the... Jul 2022Within cellular barriers, cells are separated by basement membranes (BMs), nanometer-thick extracellular matrix layers. In existing in-vitro cellular-barrier models,...
Within cellular barriers, cells are separated by basement membranes (BMs), nanometer-thick extracellular matrix layers. In existing in-vitro cellular-barrier models, cell-to-cell signaling can be preserved by culturing different cells in individual chambers separated by a semipermeable membrane. Their structure does not always replicate the BM thickness nor diffusion through it. Here, a porous polymeric nanofilm made of poly(D-L-lactic acid) (PDLLA) is proposed to recreate the BM in a microfluidic blood-brain-barrier model. Nanofilms showed an average thickness of [Formula: see text] and a maximum pore diameter of 1.6 μm. Human umbilical vein endothelial cells (HUVECs) were cultured on PDLLA. After 7 days, viability was >95% and cell morphology did not show relevant differences with HUVECs grown on control substrates. A protocol for suspending the nanofilm between 2 microfluidic chambers was identified and showed no leakage and good sealing. Clinical Relevance- Preclinical models of cellular barriers are a key step towards a deeper understanding of their roles in pathogenesis of various diseases: a physiologically relevant microfluidic model of the blood brain barrier (BBB) allows high-throughput investigations of BBB contribution in neurodegenerative diseases and cruelty-free screenings of drugs targeting the brain.
Topics: Blood-Brain Barrier; Brain; Cell Culture Techniques; Cells, Cultured; Human Umbilical Vein Endothelial Cells; Humans
PubMed: 36086504
DOI: 10.1109/EMBC48229.2022.9870981 -
Materials (Basel, Switzerland) Aug 2023In this study, CoFeBDy thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with...
In this study, CoFeBDy thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with thicknesses of 10, 20, 30, 40, and 50 nm, and heat-treated in a vacuum annealing furnace at 100, 200, and 300 °C. Various instruments were used to examine and analyze the effects of roughness on the magnetic, adhesive, and mechanical properties. From the low frequency alternating current magnetic susceptibility (χ) results, the optimum resonance frequency is 50 Hz, and the maximum χ value tends to increase with the increase in the thicknesses and annealing temperatures. The maximum χ value is 0.18 at a film thickness of 50 nm and an annealing temperature of 300 °C. From the four-point probe, it is found that the resistivity and sheet resistance values decrease with the increase in film deposition thicknesses and higher annealing temperatures. From the magnetic force microscopy (MFM), the stripe-like magnetic domain distribution is more obvious with the increase in annealing temperature. According to the contact angle data, at the same annealing temperature, the contact angle decreases as the thickness increases due to changes in surface morphology. The maximal surface energy value at 300 °C is 34.71 mJ/mm. The transmittance decreases with increasing film thickness, while the absorption intensity is inversely proportional to the transmittance, implying that the thickness effect suppresses the photon signal. Smoother roughness has less domain pinning, more carrier conductivity, and less light scattering, resulting in superior magnetic, electrical, adhesive, and optical performance.
PubMed: 37687687
DOI: 10.3390/ma16175995 -
Skin Research and Technology : Official... Jan 2023This study aimed to investigate the effect of fat-layer thickness and focal depth on the pressure and temperature distribution of tissue.
INTRODUCTION
This study aimed to investigate the effect of fat-layer thickness and focal depth on the pressure and temperature distribution of tissue.
METHODS
Computer simulations were performed for the skin-fat layer models during high-intensity focused ultrasound (HIFU) treatment. The acoustic pressure field was calculated using the nonlinear Westervelt equation and coupled with the Pennes bioheat transfer equation to obtain the temperature distribution. To investigate the effect of the thickness of the fat layer on pressure and thermal distributions, the thickness of the fat layer behind the focal point (z = 13.5 mm) changed from 8 to 24 mm by 2 mm step. The pressure and temperature distribution spectra were extracted.
RESULTS
The simulated results were validated using the experimental results with a 98% correlation coefficient (p < 0.05). There was a significant difference between the pressure amplitude and temperature distribution for the 8-14 mm thickness of the fat layer (p < 0.05). By changing the focal point from 11.5 to 13.5 mm, the maximum acoustic pressure at the focal point increased 66%, and the maximum temperature was 56%, respectively.
CONCLUSION
Considering the specific treatment plan for each patient, according to the skin and fat layer thicknesses, can help prevent side effects and optimize the treatment process of HIFU.
Topics: Humans; Computer Simulation; High-Intensity Focused Ultrasound Ablation; Plastic Surgery Procedures; Skin; Temperature; Lipectomy
PubMed: 36704882
DOI: 10.1111/srt.13280 -
Dental Materials : Official Publication... Jan 2022To determine the minimum thickness required for a monolithic hybrid ceramic crown on different substrates (soft vs stiff) used in posterior dentition for bruxism.
OBJECTIVES
To determine the minimum thickness required for a monolithic hybrid ceramic crown on different substrates (soft vs stiff) used in posterior dentition for bruxism.
METHODS
80 polymer-infiltrated ceramic networks Vita Enamic (PICN VE) disc specimens with four different occlusal thicknesses (0.8, 1.2, 1.6 and 2.0 mm), were produced using a computer-aided design/manufacturing system, and cemented on a stiff (zirconia) or soft (polyamide) substrate of 4-mm thickness. The ten specimens, in soft or stiff groups, were subjected to compressive loading by a MTS machine until fracture or maximum load (4500 N) was reached. The unbroken specimens were examined using optical coherence tomography. Eight axisymmetric finite element models and eight 3D models comprising the four different occlusal thicknesses and two substrates under different vertical loads and sliding movements were constructed. The maximum principal stress was selected to evaluate the stress distribution in this study.
RESULTS
The fracture resistance of the specimens was significantly different between the two substrates (P < 0.001). Fracture resistance was positively associated with specimen thickness (r = 0.597 and 0.896 for the soft and stiff substrate respectively). Specimens on the soft substrate had lower fracture loads, whilst cone cracks were observed in unbroken samples on different soft/stiff substrate prior to final fracture. The finite element analysis confirmed that samples on the stiff substrate had lower maximum principal stress values than those on the soft substrate. For the maximum principal stress not to exceed the flexural strength of PICN VE, a stiff substrate and minimum thickness of 2.0 mm are required for the prostheses.
SIGNIFICANCE
A minimum 2.0 mm thick, stiff substrate was needed for bruxism as shown by the effect of high/large chewing force on the posterior dentition of monolithic PICN VE crowns.
Topics: Bruxism; Ceramics; Computer-Aided Design; Crowns; Dental Porcelain; Dental Restoration Failure; Dental Stress Analysis; Humans; Materials Testing; Zirconium
PubMed: 34785045
DOI: 10.1016/j.dental.2021.10.010 -
Polymers Aug 2023This paper aimed to experimentally clarify the dynamic crushing performance of expanded polyethylene (EPE) and analyze the influence of thickness and dropping height on...
This paper aimed to experimentally clarify the dynamic crushing performance of expanded polyethylene (EPE) and analyze the influence of thickness and dropping height on its mechanical behavior based on the stress-energy method. Hence, a series of impact tests are carried out on EPE foams with different thicknesses and dropping heights. The maximum acceleration, static stress, dynamic stress and dynamic energy of EPE specimens are obtained through a dynamic impact test. Then, according to the principle of the stress-energy method, the functional relationship between dynamic stress and dynamic energy is obtained through exponential fitting and polynomial fitting, and the cushion material constants , and are determined. The maximum acceleration-static stress curves of any thickness and dropping height can be further fitted. By the equipartition energy domain method, the range of static stress can be expanded, which is very fast and convenient. When analyzing the influence of thickness and dropping height on the dynamic cushioning performance curves of EPE, it is found that at the same drop height, with the increase of thickness, the opening of the curve gradually becomes larger. The minimum point on the maximum acceleration-static stress curve also decreases with the increase of the thickness. When the dropping height is 400 mm, compared to foam with a thickness of 60 mm, the tested maximum acceleration value of the lowest point of the specimen with a thickness of 40 mm increased by 45.3%, and the static stress is both 5.5 kPa. When the thickness of the specimen is 50 mm, compared to the dropping height of 300 mm, the tested maximum acceleration value of the lowest point of the specimen with a dropping height of 600 mm increased by 93.3%. Therefore, the dynamic cushioning performance curve of EPE foams can be quickly obtained by the stress-energy method when the precision requirement is not high, which provides a theoretical basis for the design of cushion packaging.
PubMed: 37688229
DOI: 10.3390/polym15173603 -
International Journal of Retina and... May 2021Idiopathic epiretinal membrane (iERM) is a common retinal disease in the elderly population. The exact pathogenesis of iERM is unknown. The present study aimed to...
BACKGROUND
Idiopathic epiretinal membrane (iERM) is a common retinal disease in the elderly population. The exact pathogenesis of iERM is unknown. The present study aimed to evaluate the relationship between aqueous flare and morphology of iERM using swept-source optical coherence tomography (OCT).
METHODS
A consecutive series of 36 eyes of 33 patients with iERM and 109 control eyes of 109 patients were retrospectively examined. Aqueous flare measurements and OCT images were obtained on the same day. The average total retinal, inner retinal, outer retinal, and choroidal thicknesses were calculated using the thickness map mode with an Early Treatment Diabetic Retinopathy Study nine-zone grid that was divided into three zones. The maximum depth of the retinal folds in iERMs was manually measured. The correlation among flare value, maximum depth of folds, and retinal and choroidal thicknesses was evaluated. The morphological changes between the control eyes and the eyes with iERM in different stages were examined.
RESULTS
The result demonstrated a significant positive correlation between the aqueous flare value and total and inner retinal thicknesses in the early stage of iERM. There was a significant positive correlation between the maximum depth of folds and total and inner retinal thicknesses in the early stage of iERM, and the maximum depth of folds significantly increased in the advanced stage. The total and inner retinal thicknesses and proportion of inner retinal thickness significantly increased as the stage of iERM progressed.
CONCLUSIONS
The aqueous flare value was associated with retinal thickness in the early stage of iERM, which supports the idea that inflammation or breakdown of blood-ocular barrier is involved in the process of iERM formation. The maximum retinal folds increased as the stage of iERM progressed and retinal thickness increased, which indicates that the tangential force increases as the iERM stage progresses.
PubMed: 34001276
DOI: 10.1186/s40942-021-00294-9 -
Materials (Basel, Switzerland) Nov 2015Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main... (Review)
Review
Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main problems is fabricating a multilayer structure, and one solution attracting growing interest is the use of lead-free multilayer piezoelectric ceramics. The paper reviews work that has been done by the authors on lead-free alkali niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes. However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free alkali niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain (/) of a representative alkali niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where denotes the maximum strain and denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. In the paper, the compositional design and process used to co-fire lead-free ceramics with nickel inner electrodes are introduced, and their piezoelectric properties and reliabilities are shown. Recent advances are introduced, and future development is discussed.
PubMed: 28793646
DOI: 10.3390/ma8115389