Angle Values Research Articles

Is dark energy necessary for the sustainability of traversable wormholes?

Abstract Dark energy is usually the principal ingredient needed for traversability of wormholes by providing the negative gravity effect to keep the throat open. But can the same be achieved without dark energy? It turns out that if we couple the trace of energy-momentum with the standard Einstein-Hilbert Lagrangian and utilise a specific equation of state then dark energy may be obviated. The Casimir stress energy is known to result in the violation of the null energy condition (NEC) on the energy momentum tensor. This phenomenon makes such an equation of state (EoS) an ideal candidate to generate traversable wormhole (WH) geometries. The laboratory proven phenomenon provides a natural mechanism to sustain an open WH throat without having to appeal to dark energy. We generate two classes of WH solutions with this in energy-momentum trace-coupling gravity.
 For the specific choice of the Casimir EoS relating the energy-momentum tensor components [ Kar and Sahdev: Phys. Rev D {\bf 52} 2030 (1995)] and different choices for redshift functions, we determine the WH geometry completely. The obtained WH solutions violate the NECs and all qualitative constraints demanded of physically realisable WHs are satisfied. This is demonstrated via graphical plots for a suitably chosen range of values of the coupling parameter. Furthermore, our study involved an investigation into the repulsive effect of gravity, which revealed that its presence leads to a negative deflection angle for photons traveling along null geodesics. Notably, we observed a consistent pattern of negative values for the deflection angle across all values of $r_0$ in the three scenarios considered, thus indicating the clear manifestation of the repulsive gravity effect. All of this is possible without invoking the existence of dark energy.

Modification of high-density polyethylene-based separator to improve lithium-ion battery performance using nano-silica and maleic anhydride

Due to its good mechanical properties and chemical stability, high-density polyethylene (HDPE) has become a fantastic polyolefin for its application in lithium-ion batteries (LIBs) as the separator of electrodes. In this work, nano-silica as a mineral material and maleic anhydride as the compatibilizer of HDPE-silica were used at different combinations to promote the HDPE-based separator efficiency. According to the results, maleic anhydride caused a perfect distribution of nano-silica particles in the polymer media leading to increasing its porosity and reducing the separator heat-shrinkability by 98 %. Also, they improved the compound electrolyte absorption from 49.4 to 94.2 % which led to a decrease in the contact angle value from 65 to 40.2 degrees. The thermal analysis showed a ~10 % reduction in the compound crystallinity without any significant change in the melting point. The obtained data indicated that the HDPE separators made of 5 wt% silica and maleic anhydride are the best candidates for LIBs. The mentioned formulation decreased the separator resistance from 860 and 410 Ω, electrolyte resistance from 13 to 8 Ω, and the increment of the ion conductivity from 0.78 to 1.24 × 10−3 S.cm−1, the LIB capacities from 99.8 to 129.8 mAh/g and 97.8 to 127.59 mAh/g at the charge and discharge processes.

Non-coplanar CBCT image reconstruction using a generative adversarial network for non-coplanar radiotherapy.

To develop a non-coplanar cone-beam computed tomography (CBCT) image reconstruction method using projections within a limited angle range for non-coplanar radiotherapy. A generative adversarial network (GAN) was utilized to reconstruct non-coplanar CBCT images. Data from 40 patients with brain tumors and two head phantoms were used in this study. In the training stage, the generator of the GAN used coplanar CBCT and non-coplanar projections as the input, and an encoder with a dual-branch structure was utilized to extract features from the coplanar CBCT and non-coplanar projections separately. Non-coplanar CBCT images were then reconstructed using a decoder by combining the extracted features. To improve the reconstruction accuracy of the image details, the generator was adversarially trained using a patch-based convolutional neural network as the discriminator. A newly designed joint loss was used to improve the global structure consistency rather than the conventional GAN loss. The proposed model was evaluated using data from eight patients and two phantoms at four couch angles (±45°,±90°) that are most commonly used for brain non-coplanar radiotherapy in our department. The reconstructed accuracy was evaluated by calculating the root mean square error (RMSE) and an overall registration error ε, computed by integrating the rigid transformation parameters. In both patient data and phantom data studies, the qualitative and quantitative metrics results indicated that±45° couch angle models performed better than±90° couch angle models and had statistical differences. In the patient data study, the mean RMSE and ε values of couch angle at 45°, -45°, 90°, and -90° were 58.5 HU and 0.42mm, 56.8 HU and 0.41mm, 73.6 HU and 0.48mm, and 65.3 HU and 0.46mm, respectively. In the phantom data study, the mean RMSE and ε values of couch angle at 45°, -45°, 90°, and -90° were 91.2 HU and 0.46mm, 95.0 HU and 0.45mm, 114.6 HU and 0.58mm, and 102.9 HU and 0.52mm, respectively. The results show that the reconstructed non-coplanar CBCT images can potentially enable intra-treatment three-dimensional position verification for non-coplanar radiotherapy.

Transient thermal fracture analysis of a honeycomb layer with a central crack

Auxetic honeycomb materials with negative Poisson’s ratio received rapidly growing attention in recent years owing to their exceptional thermomechanical properties in constructing sandwich composites. The objective of this article is to investigate the transient thermal behavior and fracture risk of a honeycomb layer with a central crack subject to a sudden thermal shock by theoretical modeling. Two different material configurations along both orthogonal directions, as well as the conventional and auxetic hexagonal alumina honeycomb cells, are examined to illustrate their effects on the thermal stress intensity factors. To solve the thermoelastic governing equations subject to complex boundary conditions, the methodology of integral transform with singular integral equation is employed. The numerical results demonstrate that the auxetic honeycombs can reduce the thermal stress intensity factors significantly compared to their conventional counterparts. The ratio of stress intensity factors in auxetic to non-auxetic honeycombs under the same absolute value of the internal cell angle θ decreases monotonically with increasing |θ|. In addition, the effects of the relative density, crack length, and crack position are investigated. Our findings would provide a more comprehensive understanding of the honeycomb’s fracture behaviors and contribute to the material design of the sandwich composites with honeycomb cores.

Tuning the Properties of Xylan/Chitosan-Based Films by Temperature and Citric Acid Crosslinking Agent.

Petroleum-based food packaging causes environmental problems such as waste accumulation and microplastic generation. In this work, biobased films from stable polyelectrolyte complex suspensions (PECs) of xylan and chitosan (70 Xyl/30 Ch wt% mass ratio), at different concentrations of citric acid (CA) (0, 2.5, 5, 7.5 wt%), were prepared and characterized. Films were treated at two temperatures (135 °C, 155 °C) and times (30 min, 60 min) to promote covalent crosslinking. Esterification and amidation reactions were confirmed by Fourier Transform Infrared Spectroscopy and Confocal Raman Microscopy. Water resistance and dry and wet stress-strain results were markedly increased by thermal treatment, mainly at 155 °C. The presence of 5 wt% CA tended to increase dry and wet stress-strain values further, up to 88 MPa-10% (155 °C for 60 min), and 5.6 MPa-40% (155 °C for 30 min), respectively. The UV-blocking performance of the films was improved by all treatments, as was thermal stability (up to Tonset: 230 °C). Contact angle values were between 73 and 84°, indicating partly wettable surfaces. Thus, thermal treatment at low CA concentrations represents a good alternative for improving the performance of Xyl/Ch films.

ECAD study: Evaluating agreement degree among paediatricians in hip dysplasia assessment by the Graf ultrasound method.

Developmental dysplasia of the hip (DDH) is the most common musculoskeletal anomaly of childhood. This study analyses paediatrician's concordance performing hip ultrasound according to Graf's method. An analytical cross-sectional study is designed. Patients' hips are evaluated by Graf's ultrasound method at 4-6 and 12-16weeks of age. Demographic characteristics, pregnancy history, factors related to DDH, hip type, and α and β angles are collected. To assess the agreement degree of hip diagnosis and hip types Kappa index (I. kappa) is used. Intraclass correlation coefficient (ICC) evaluates the concordance of α and β angles. A p value < 0.05 is considered statistically significant. All results are represented with their 95% confidence interval (95% CI). Four hundred sixty-seven neonates are recruited and meet the inclusion criteria. A total of 3182 images were analysed. Agreement between paediatricians according to hip diagnosis and different types ranges from moderate to almost perfect I. kappa 0.6-1.0 (95% CI 0.5-0.7; 95% CI 1.0-1.0). α angle ICC for paediatricians is between 0.75 and 0.88 (95% CI 0.61-0.86; 95% CI 0.80-0.92). β angle value agreement degree among paediatricians at both visits is moderate. The Graf method is the most popular ultrasound technique for hip assessment. In our setting, paediatricians carry out children follow-up; therefore, they should perform universal screening. In this study agreement degree between paediatricians varies between substantial and almost perfect. Conclusion: The Graf ultrasound procedure performed by paediatricians is a reliable test and can be used for DDH screening. What is Known •Developmental dysplasia of the hip (DDH) is the most common congenital musculoskeletal anomaly of childhood. Early diagnosis and treatment improve DDH prognosis. Lack of detection can cause complications such as lameness, early osteoarthritis and need for hip replacement at an early age. What is New •Today, the best screening method is still subject of debate. But it seems that with selective screening many pathological hips go unnoticed. Universal screening implementation may be a challenge in some countries. But the question is if this could be carried out by paediatricians as part of healthy child follow-up.

Development of low temperature cure hybrid benzoxazine-epoxy resins for thermally stable and moisture resistant applications

New type of diallyl bisphenol-A (ABA) based benzoxazines and benzoxazine resins tailored with epoxy groups for low-temperature curing, have been developed using various curatives for high performance applications. The molecular structure of the synthesized compounds was analyzed using HRMS, 1H NMR, 13C NMR and ATR-FTIR analytical techniques. The cure behavior (Tp) of benzoxazine (Bz) and benz-epoxy (Bz-Ep) resin in the absence and presence of different nature of curatives were studied using DSC to evaluate their applicability for advanced composite applications. The values of Tp obtained are 279 °C, 190 °C and 247 °C for ABA-a, ABA-dmapa and ABA-ipa respectively. The cure behavior has been further lowered by converting ally group present in the benzoxazine has been transformed into epoxy groups by appropriate mechanism. The curing (Tp) temperature observed for hybrid ABA-a-Ep, ABA-dmapa-Ep and ABA-ipa-Ep benz-epoxy resins are 151 °C, 226 °C and 160 °C, 187 °C and 150 °C, 211 °C respectively. The Tp of different benz-epoxy resin systems studied in the presence of catalysts were found to be in the range of 101-155 °C. With a Tmax of 484 °C and a char yield of 43 %, poly(ABA-a) exhibits impressive thermal stability when compared to other synthesized polybenzoxazines. Further, incorporating various curatives into the benz-epoxy matrix enhances its thermal stability and char yield compared to the neat matrices. Additionally, the developed samples exhibit excellent moisture resistant (0.75 %) and hydrophobic nature with the highest contact angle value of 152o for poly(ABA-a). The findings from various studies indicate that the hybrid benz-epoxy resins demonstrate characteristics such as low-temperature curability, thermal stability, hydrophobicity. These results render them appropriate for a diverse array of high-performance industrial and engineering uses.

The superior mesenteric artery angle in diagnosis of nutcracker syndrome: a systematic review and meta-analysis.

Nutcracker syndrome (NCS) can be caused by narrowness of the superior mesenteric artery (SMA) angle. Nevertheless, the cut-off value of the SMA angle is controversial and variable. Therefore, the present study evaluated the optimal SMA angle to maximize diagnostic performance for NCS diagnosis by conducting a meta-analysis. We comprehensively searched the English literature related to the diagnosis of NCS from the perspective of SMA (from the date of database inception to June 2022). The accuracy of an SMA angle less than 41° in the diagnosis of NCS was evaluated by calculating the pooled sensitivity (SEN), pooled specificity (SPE), positive likelihood ratio (LR+), negative likelihood ratio (LR-), summary receiver operating characteristic (SROC) curve and area under the curve (AUC) value. The I2 test and meta-regression analysis were used to assess heterogeneity and sources of heterogeneity, respectively. Publication bias was assessed using Deeks' funnel plot asymmetry test. Six studies (526 patients) met the inclusion criteria. SEN and SPE were 0.94 (95% confidence interval (CI) 0.80-0.99) and 0.85 (95% CI 0.65-0.94), respectively. The LR + value was 6.0, and the LR- value was 0.07, revealing that SMA angles less than 41° exhibited an excellent ability to help confirm or exclude NCS. Additionally, SROC curves showed that the AUC of SMA angles less than 41° for the diagnosis of NCS was 0.96, indicating that SMA angles less than 41° have good efficacy for helping to diagnose NCS. This study explored the diagnostic efficacy of the cut-off value of the SMA angle by meta-analysis. According to the high SPE and SEN results, SMA angles less than 41° have good efficacy in facilitating NCS diagnosis.

Stability of the Dentin-Bonded Interface Using Self-Etching Adhesive Containing Diacrylamide after Bacterial Challenge.

Purpose/Aim: Acrylamides are hydrolytically stable at pH lower than 2, and were shown to preserve bonded interface integrity with two-step, total etch adhesives. The objective of this study was to leverage those two characteristics in self-etching primers containing the acidic monomer 10-MDP and test the microtensile bond strength before and after incubation with S. mutans incubation. Materials and Methods: Acidic primers (10 wt % 10-methacryloyloxydecyl dihydrogen phosphate─10-MDP; 45 wt % N,N-diethyl-1,3-bis(acrylamido)propane─DEBAAP, or 2-hydroxyethyl methacrylate─HEMA; 45 wt %, glycerol-dimethacrylate─GDMA) and adhesives (DEBAAP or HEMA/10-MDP/UDMA 45/10/45 wt %) were made polymerizable by the addition of 0.2 wt % camphorquinone, 0.8 wt % ethyl-4-dimethylaminobenzoate, 0.4 wt % diphenyliodonium hexafluorophosphate, and 0.1 wt % butylhydroxytoluene. Nonsolvated materials were characterized for flexural strength (FS), modulus (E), toughness, water sorption/solubility (WS/SL), contact angle, and vinyl conversion (DC). Viscosity was evaluated after adding 20 and 40 vol % ethanol to the primer and adhesive, respectively. The experimental materials or Clearfil SE Bond (CC─commercial control) were used to bond a commercial composite (Filtek Supreme) to the flat surface of human dentin. Microtensile bond strength (MTBS) was tested in 1 mm2 sticks for the 5 primer/bond combinations: CC (Clearfil Bond Primer and Bond), HH (HEMA/HEMA), DD (DEBAAP/DEBAAP), HD (HEMA/DEBAAP), and DH (DEBAAP/HEMA). Prior to testing, sticks were stored in water or biofilm-inducing culture medium with S. mutans for 1 week. Confocal images and FTIR-ATR evaluation evaluated the hybrid layer of the adhesives. Results were analyzed using Student's t-test (WS, SL, DC, contact angle, FS, E, toughness), one-way ANOVA/Tukey's test for viscosity, and two-way ANOVA/Tukey's test for MTBS (95%). Results: HEMA-based materials had lower contact angle (p = 0.004), higher WS (p < 0.001), and similar SL values compared to DEBAAP (p = 0.126). FS (p = 0.171) and E (p = 0.065) dry values were similar, but after one week of water storage, FS/E dropped more significantly for HEMA materials. Dry and wet toughness was greater for DEBAAP (p < 0.001), but it also had the greatest drop (46%). Clearfil bonds had the highest viscosity, followed by DEBAAP and HEMA, respectively (p = 0.002). For the primers, HEMA had the lowest viscosity (p = 0.003). As far as MTBS, all groups tested in water were statistically different when compared with HH (p < 0.001). After storage in biofilm, DH had the highest MTBS value, being statistically different from HH (p = 0.002), CC (p = 0.015), and DD (p = 0.027). Conclusions: The addition of a diacrylamide and its association with HEMA in self-etching adhesive systems provided greater bonding stability after bacterial challenge.

Phase angle measured by bioelectrical impedance analysis in patients with chronic obstructive pulmonary disease: Associations with physical inactivity and frailty

BackgroundFactors associated with early-stage frailty (pre-frailty) in patients with chronic obstructive pulmonary disease (COPD) remain unestablished. In addition to skeletal muscle quantity, skeletal muscle dysfunction can be estimated using an angular metric from bioelectrical impedance analyzer (BIA), termed the phase angle, that reflects cell membrane reactance representing the structural stability. This study examined whether the phase angle was more closely associated with pre-frailty compared with skeletal muscle quantity in patients with COPD. MethodsThis cross-sectional analysis included stable smokers with and without COPD whose frailty status was assessed using the Japanese version of the Cardiovascular Health Study criteria. The phase angle and skeletal muscle index (SMI) were measured using BIA, and physical activity over one week was assessed using triaxial accelerometers. ResultsA total of 159 patients were categorized into robust, pre-frail, and frail groups (n = 38, 92, and 29, respectively). The phase angle was significantly smaller in the pre-frail and frail groups than in the robust group after adjusting for age, sex, height, body mass index, smoking history, and lung function. In contrast, SMI did not differ between the robust and pre-frail groups. When combining the pre-frail and frail groups into a non-robust group, 4.8° was determined as the cutoff phase angle value to identify non-robust status. A phase angle <4.8° was associated with shorter durations of moderate-intensity physical activity but not with light physical activity. ConclusionsA smaller phase angle was associated with pre-frailty and impaired moderate-intensity physical activity in smokers with and without COPD.

X-ray characterization, structural analysis, antibacterial activity, and self-cleaning property of Cu-doped TiO2-SiO2 nanocomposite prepared by sonochemical process

TiO2-SiO2 nanocomposites with different copper (Cu) precursor loadings were prepared by a one-step sonochemical process. The mole ratio of Cu precursor in TiO2-SiO2 composite was varied at 0.004, 0.008, 0.020, and 0.040, respectively. The specific X-ray characterization techniques on crystalline structure, chemical composition, and chemical states of Cu-doped TiO2-SiO2 composite were carried out by X-ray diffraction technique (XRD), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS), respectively. Surface morphology and chemical bonding of Cu-doped TiO2-SiO2 composite were monitored by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectrophotometer (FTIR). For antibacterial properties, the inhibition zone of antimicrobial activity was investigated by varying amounts of Cu precursors in the TiO2-SiO2 composite. After that, Cu-doped TiO2-SiO2 composite powder with different Cu precursor ratios was mixed in PMMA solution and deposited on glass slides to study the optical property and hydrophilicity by UV-VIS-NIR spectrophotometer and contact angle method. XRD patterns of Cu-doped TiO2-SiO2 nanocomposites show the formation of the main TiO2 anatase phase with the ultrafine particles observed by FE-SEM images. FT-IR spectra of the composites are assigned to the prominent peaks of the Ti-O-Ti and Ti-O-Si bond relating to the TiO2-SiO2 host matrix. Meanwhile, TiO2-SiO2 composites with Cu precursor at 0.004 mol ratio can significantly enhance the antibacterial activity with a large inhibition zone. The contact angle value of Cu-doped TiO2-SiO2 nanocomposite film at 0.040 Cu precursor mole ratio in the TiO2-SiO2 matrix resulted in the optimized composite ratio for achieving a hydrophilic surface on the substrate.

Determining patterns in the separation of hemp seed hulls

The subject of this study is the technological processes of separation, the hull of industrial hemp seeds, an aspiration column, and whole kernels. The problem solved was determining the technical and technological solutions that could enable the intensification of production processes for separating industrial hemp seeds. The separation of hemp seed hull by linear dimensions on sieves with round and elongated holes has been investigated. It was found that the percentage of seed hulls retained by sieves with circular holes was 25.98 % for ø3.5 mm, 23.59 % for ø3.0 mm, and 40.28 % for ø2.0 mm, respectively. Sieves ø3.5 mm and ø2.0 mm made it possible to obtain seed hulls fractions with two components conditionally different in the «mass-size» ratio. Using sieves with elongated holes enabled obtaining fractions consisting of at least three components. Sieves with elongated working holes of 3.0×20 mm, due to their low ability (1.76 %) to retain hemp seed hull components, were ineffective. The clogging levels of kernels in seed hulls, separated by linear dimensions on combined sieves with round and elongated holes, were as follows: separation option No. 1 – 48.70 %, option No. 2 – 45.74 %, option No. 3 – 60.25 %, option No. 4 – 49.32 %, respectively. It was established that the use of an aspiration column made it possible to remove up to 32.1 % of clogging in the form of a light fraction. The application of the aspiration column reduced the content of seed coating in separation option No. 1 by 3.0–5.7 times, option No. 2 by 1.35–3.7 times, option No. 3 by 1.9–11.2 times, and option No. 4 by 1.5–4.8 times, respectively. The quantitative and component composition of seed hulls fractions obtained under conditions of using an aspiration column with set rational values of the air damper opening angle α=53° and the vertical tilt angle of the air channel β=6°, was as follows: Stage I – «heavy» fraction – 51.78 %, 27.56 % – waste, up to 20 % – «light» fraction of Stages II and III

Human-redundant robot interaction and redundancy utilization based on three-dimensional force sensor

To make full use of redundant characteristics, the inverse kinematics algorithm based on augmented Jacobian matrix with the goal of avoiding joint limit and obstacle is adopted. Then, admittance control system is established for human-robot interaction, and force control is converted into motion control of robot. Through the expansion of Jacobian matrix, the model of joint limit avoidance is established. Regarding obstacle avoidance in human-robot interaction process, the potential function gradient is calculated and augmented Jacobian matrix is formed. Thus, comprehensive control model of human-robot interaction and obstacle avoidance is established. When the external force is applied, the robot can move smoothly along the human hand. The robot's motion process is smooth and compliant. At the same time, when performing task of avoiding joint limit, the values of the joint angle are within the set range. The average angle margin of the four joints is over 60 %. So the goal of avoiding the joint limit is achieved. When adding obstacle avoidance in the interaction control, the difference value between the minimum distance and safe distance is always positive. The safety margin of the distance is over 20 %. So the robot does not contact with the obstacle. So human-robot interaction and redundancy utilization can be realized simultaneously.

Synthesis and characterization of stretchable isoprene-acrylic acid copolymer thin films

Copolymer thin films of isoprene with acrylic acid were synthesized using PECVD. In that way, the stretchable functionality of polyisoprene (PI) was combined with the hydrophilic functionality of poly(acrylic acid) (PAA) to obtain stretchable thin films with adjustable wettabilities. Deposition rates were found to change between 9 and 5.5 nm/min depending on the monomer flowrates. The analysis of water contact angle (WCA) values indicated that films having more AA units in their structures were more wettable. The stretchability of the films was assessed on laboratory gloves through stretch-release test and on PET sheet through bend-release test. No significant changes in the WCA values with no observable cracks and failures after successive tests were indication of stretchability of the copolymer films.

Study on the Properties of TiC Coating Deposited by Spark Discharge on the Surface of AlFeCoCrNiCu High-Entropy Alloy.

Titanium carbide (TiC) coatings were prepared on the surface of AlFeCoCrNiCu high-entropy alloy blocks using electro-spark deposition (ESD). The microhardness and corrosion resistance of the TiC coatings prepared under different voltage and capacitance process parameters were studied. The research shows that the maximum microhardness of the TiC coating on sample 4 (working voltage of 20 V, working capacitance of 1000 μF) is 844.98 HV, which is 81.5% higher than the microhardness of the substrate. This is because the deposition energy increases with the increase in voltage, and the adhesion and aggregation between the coating and the substrate are enhanced, increasing the hardness of the coating. It is worth noting that excessive deposition energy can increase surface defects and reduce the microhardness of the coating surface. Electrochemical testing analysis shows that the corrosion current density of the TiC coating is the lowest (9.475 × 10-7 ± 0.06 × 10-7), and the coating impedance is the highest (2.502 × 103 Ω·com2). The absolute phase angle value is the highest (about 72°). The above indicates that the TiC coating prepared with a working voltage of 20 V and a working capacitance of 1000 μF has better microhardness and corrosion resistance.

Morphological changes in flatfoot: a 3D analysis using weight-bearing CT scans

BackgroundFlatfoot is a condition resulting from complex three-dimensional (3D) morphological changes. Most Previous studies have been constrained by using two-dimensional radiographs and non-weight-bearing conditions. The deformity in flatfoot is associated with the 3D morphology of the bone. These morphological changes affect the force line conduction of the hindfoot/midfoot/forefoot, leading to further morphological alterations. Given that a two-dimensional plane axis overlooks the 3D structural information, it is essential to measure the 3D model of the entire foot in conjunction with the definition under the standing position. This study aims to analyze the morphological changes in flatfoot using 3D measurements from weight-bearing CT (WBCT).MethodIn this retrospective comparative our CT database was searched between 4–2021 and 3–2022. Following inclusion criteria were used: Patients were required to exhibit clinical symptoms suggestive of flatfoot, including painful swelling of the medial plantar area or abnormal gait, corroborated by clinical examination and confirmatory radiological findings on CT or MRI. Healthy participants were required to be free of any foot diseases or conditions affecting lower limb movement. After applying the exclusion criteria (Flatfoot with other foot diseases), CT scans (mean age = 20.9375, SD = 16.1) confirmed eligible for further analysis. The distance, angle in sagittal/transverse/coronal planes, and volume of the two groups were compared on reconstructed 3D models using the t-test. Logistic regression was used to identify flatfoot risk factors, which were then analyzed using receiver operating characteristic curves and nomogram.ResultThe flatfoot group exhibited significantly lower values for calcaneofibular distance (p = 0.001), sagittal and transverse calcaneal inclination angle (p < 0.001), medial column height (p < 0.001), sagittal talonavicular coverage angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.015) Hibb angle. In contrast, the sagittal lateral talocalcaneal angle (p = 0.013), sagittal (p < 0.001) and transverse (p = 0.004) talocalcaneal angle, transverse talonavicular coverage angle (p < 0.001), coronal Hibb angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.001) Meary’s angle were significantly higher in the flatfoot group. The sagittal Hibb angle (B = − 0.379, OR = 0.684) and medial column height (B = − 0.990, OR = 0.372) were identified as significant risk factors for acquiring a flatfoot.ConclusionThe findings validate the 3D spatial position alterations in flatfoot. These include the abduction of the forefoot and prolapse of the first metatarsal proximal, the arch collapsed, subluxation of the talonavicular joint in the midfoot, adduction and valgus of the calcaneus, adduction and plantar ward movement of the talus in the hindfoot, along with the first metatarsal’s abduction and dorsiflexion in the forefoot.

Numerical simulation of heat transport mechanism in chemically influenced ternary hybrid nanofluid flow over a wedge geometry

Ternary hybrid nanofluid flow over a wedge surface facilitates optimization, promotes industrial processes such as heat transfer, temperature regulation, material compatibility, energy efficiency and is very useful in equipment design. Due to this attention the current study focalizes the heat diffusion and mass transportation in ternary hybrid (TiO2-AL2O3-SiO2) nanofluid flow over a stretching/shrinking wedge geometry. Additionally, Ternary hybrid flow is examined under the impact of activation energy together with chemical reactions. The nanofluid flow process is structured using Modified Boungiorno Model together with framed set of partial differential equation (PDEs). The resulting systems is altered into non dimensional form of ordinary differential equation (ODEs) using transform functions and linearization is obtained through shooting technique. MATLAB bvp4c solver scheme is utilized for numerical findings of the problem. Influence of key parameters are analyzed on velocity, temperature, and concentration field. Fluid concentration intensifies via augmentation in activation rate whereas wedge stretching due to larger values of wedge angle, lessens velocity of fluid. Heat transportation escalate with higher values of fluid index, whereas negative trend is seen in case of higher value of Brownian parameter.

Investigation of the intelligent anti-aging bitumen using microcapsule clean-product secreting waste cooking oil through polyacrylamide-gel in porous-shell structure

The aging of bitumen is an urgent problem in pavement engineering materials. The objective of this work was to fabricate an intelligent anti-aging bitumen using a clean microcapsule product that secretes waste cooking oil through polyacrylamide (PAM)-gel in a porous shell structure. The microcapsule had a composite shell with cross-linked hexamethoxymethylmelamine as a skeleton with a porous structure and gel PAM filled in pores as the channels of the liquid waste cooking oil as core material. Aged bitumen was mixed with various microcapsules, and their physical and chemical properties were investigated. The testing results indicated that shells had successfully microencapsulated the oily rejuvenator without defects and damages. FT-IR results showed that the HMMM had been cross-linked and PAM also deposited in shells. SEM morphology showed that PAM was removed from the shell material after alcohol elution, and the shell still kept the spherical shape with a porous structure. Penetration experiments have demonstrated that PAM in the porous structure of the shell material can serve as a secretion channel for core material. Microcapsules had perfect thermal stability and homogeneous dispersion in bitumen, and there was no interface separation phenomenon. The test results showed that the bitumen/microcapsules samples gradually became softer and increased viscosity based on the viscosity changes, softening point, and penetration parameters. The tensile test also proved that adding microcapsules reduced the tensile strength of aged bitumen and increased the tensile elongation with the extension of time, which was entirely attributed to the action of the secreted rejuvenator molecules. The complex shear modulus (G*) values of bitumen/microcapsules samples gradually decreased with anti-aging time increasing at the same temperature. The phase angle values (δ) show that its value gradually decreases after the anti-aging process, indicating that the elastic composition of bitumen increases.

Implementation and Evaluation of a Gait Training Assistant for the Use of Crutches: Usability Study.

Surgical procedures on the lower extremities often require weight-bearing on crutches as part of the rehabilitation process. Orthopedic elective procedures enable patients to learn the correct use of crutches in a controlled preoperative setting. Digital assistance systems can safely circumvent a shortage of skilled staff and any contact restrictions that may be necessary. The usability of a newly developed gait training assistant (GTA) for the use of crutches will be evaluated. An intervention group trained to use crutches by the digital trainer will be compared with a control group trained to use crutches conventionally by a physiotherapist. As part of the development and implementation of a novel GTA, 14 patients learned to walk with crutches by completing specific exercises while receiving live feedback. Their movements were detected by a depth sensor and evaluated in real time. Specific parameters (step length, synchronous movement, crutch angle, and crutch distance to the feet) were compared with a control group (n=14) trained to use crutches by physiotherapists. The intervention group was also assessed by a physiotherapist. At the end of the study, the patients completed questionnaires to evaluate the usability of the system (Brooke's System Usability Scale score) and patient satisfaction. All patients trained by the novel GTA were able to use crutches correctly. The intervention group showed significantly better values for crutch angle (mean -6.3°, SD 3.5° vs mean -12.4°, SD 4.5°; P<.001) and crutch position (mean 3.3, SD 5.1 cm vs mean -8.5, SD 4.9 cm; P=.02). Both groups reported that they felt confident in the use of crutches, were able to follow the instructions, and enjoyed the training. Even though the majority (12/14, 86%) preferred physical therapy over a purely digital approach, most participants enjoyed using the system (13/14, 93%) and were interested in trying out other digital assistants (11/14, 79%). The usability of the GTA was rated above average by the majority (9/14, 64%) of the patients. The newly designed GTA is a safe method of teaching the use of crutches and is statistically superior to training by a physiotherapist. Even if patients prefer interaction with a physiotherapist over a purely digital approach, digital devices provide a safe and motivating opportunity to learn the essential locomotor skills for rehabilitation.

Formation of subwavelength tunable flat-top focus with double foci characteristic by tightly focused cylindrical vector beams

We report a numerical investigation on the generation of a subwavelength flat-top focus by tuning the polarization angle of the incident beam under tight focusing conditions. Our approach uses a binary phase mask containing two regions of opposite phases, with a variable diameter of the inner region. Properly tuning the diameter of the inner region of the mask, the flat-top profile of variable sizes (above and below the subwavelength region) is generated in a controlled manner with the various incident polarization angles of the beam and with the different numerical aperture (NA) value of the lens. Our study reveals that a particular cut-off value of polarization angle, above which the subwavelength flat-top is generated, corresponds to a specific NA that increases with the increase in the NA value. In addition, the emergence of the dual foci structure is observed in the longitudinal direction with increasing NA of the lens. The flat-top's polarization degrees-of-freedom and dual foci properties open up promising routes for potential applications in fluorescence polarization microscopy and multiplane particle trapping.