Normal Angle Research Articles

Design of Band Stop Filter Using Epsilon-Negative Frequency Selective Surface

This paper focuses on designing a band stop filter based on epsilon-negative frequency-selective surface (FSS). The unit cell has an electrical length of 0.104λ0 × 0.104λ0 which offers a bandwidth of 2.53 GHz from 1.24 GHz to 3.77 GHz. It has a center frequency of 2.44 GHz and the obtained fractional bandwidth is above 100%. Additionally, the behavior of the presented FSS is explained by the equivalent circuit model and surface current distribution. Within the entire bandwidth, it offers a negative permittivity. The refractive index of BSF is almost zero for 2.45−3.98 GHz range of frequency. The proposed FSS structure exhibits polarization-independent properties and offers a stable frequency response for normal and oblique angles under both TE and TM polarization. Good agreement between the simulated and measured results is obtained for the designed prototype.

Insights into the relationship between particulate flow characteristics and local erosion behaviour under waterjet: The role of particle-fluid-surface interaction

In this study, the erosion characteristics of eutectic high entropy alloy under the liquid–solid two-phase flow is investigated by a coupled numerical-experimental method, in order to reveal the intrinsic relationship between microscopic erosion mechanism (experimental test) and the related particle-fluid-surface interaction (CFD modelling). Furthermore, instead of the common relation between average erosion rate and mainstream flow velocity, the relationship between local erosion distribution and local particulate flow characteristics is clarified. The erosion rate and erosion pattern match well between the experiment and simulation. The results demonstrate that NiCoCrFeNb0.45 exhibits superior anti-erosion performance when compared to other widely used equipment metals. The erosion profile agrees well with the shape of surface velocity distribution, indicating a close relationship between surface erosion behaviour and flow characteristics. In particular, the erosion pattern at a normal angle appears as a symmetric ring due to the flow stagnation phenomenon, with slight erosion damage in the centre area and severe erosion in the surrounding, whereas the erosion profile at an oblique angle displays an elliptic shape, with severe erosion damage in centre. Notably, the primary erosion mechanism varies dramatically in different surface regions, induced by the various impact velocities and angles associated with the corresponding changes in the flow field. This study provides a deeper understanding of erosion behaviour in terms of the interrelationship among the material mechanical properties, particulate flow field and particle-surface impingement behaviour.

Cherry Tomato Detection for Harvesting Using Multimodal Perception and an Improved YOLOv7-Tiny Neural Network

Robotic fruit harvesting has great potential to revolutionize agriculture, but detecting cherry tomatoes in farming environments still faces challenges in accuracy and efficiency. To overcome the shortcomings of existing cherry tomato detection methods for harvesting, this study introduces a deep-learning-based cherry tomato detection scheme for robotic harvesting in greenhouses using multimodal RGB-D perception and an improved YOLOv7-tiny Cherry Tomato Detection (YOLOv7-tiny-CTD) network, which has been modified from the original YOLOv7-tiny by eliminating the “Objectness” output layer, introducing a new “Classness” method for the prediction box, and incorporating a new hybrid non-maximum suppression. Acquired RGB-D images undergo preprocessing such as color space transformation, point cloud normal vector angle computation, and multimodal regions of interest segmentation before being fed into the YOLOv7-tiny-CTD. The proposed method was tested using an AGV-based robot in a greenhouse cherry tomato farming facility. The results indicate that the multimodal perception and deep learning method improves detection precision and accuracy over existing methods while running in real time, and the robot achieved over 80% successful picking rates in two-trial mode in the greenhouse farm, showing promising potential for practical harvesting applications.

Effect of laser beam incident angle on welding of Ti6Al4V with fiber lasers

Laser beam welding (LBW) is widely used for welding Ti6Al4V alloys in aerospace applications. LBW has localized high-energy fluence with low-energy input compared to other fusion welding processes, resulting in narrower heat-affected zones. On the other hand, most metals are highly reflective when the laser beam impinges perpendicular to the surface, making the process inefficient. Hence, this work proposes to employ shallow angle incidence to reduce the reflectivity during the welding of Ti6Al4V material. To explore the potential of this idea, the current study focuses on studying the effect of laser incident angle (15°-90°), power (300 W-1500 W), and feed rate (10 mm/s-25 mm/s) on autogenous weld bead geometry. For this purpose, bead-on plate (BOP) LBW is conducted on mill-annealed Ti6Al4V material of dimensions 25 mm × 25 mm × 3 mm by employing a fiber laser source with a maximum power of 3 kW and a wavelength of 1080 nm. It is observed from the results that at a normal incident angle and low laser power (< 600 W), the penetration depth is too low to generate a weld bead. Analyzing the cross-section of the weld bead, obtained from SEM, perpendicular to the weld direction reveals that the increase in laser incident angle up to an optimal angle resulted in increased bead dimensions (width and height), and beyond that, the dimensions decreased. However, the optimal incident angle changed when the laser power was changed. The major finding of this study is that at 600 W and a normal incident angle, the laser could not penetrate and generate a weld bead due to low absorptivity, while at an incident angle of 300, 450, and 600, weld beads are generated because of increased absorptivity. Similarly, the increase in weld dimensions with the increase in laser power is observed. At higher laser power, underfill and oxide formation are observed. The feed rate is less predominant than the incident angle and the power.

Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data

Here are analyzed 3D velocity distribution functions (VDFs) of protons in the suprathermal energy-per-charge (E/Q) domain of 6.2 to 223.1 keV/e, as observed by the WIND Suprathermal Ion Composition Spectrometer (WIND/STICS) between 1995 and 2019, upon passage of interplanetary (IP) shocks. “Suprathermal” designates energies above the bulk, “thermal” solar wind, including inner-source pickup ions, cometary ions, solar energetic particles, and suprathermal tail particles. Within the WIND/STICS measurements, here treated as a standalone data set, only 3D VDFs within 9 hr prior to and following the shock passage are selected, as identified by the Center for Astrophysics (CfA) Harvard Interplanetary Shock Database. These are subsequently averaged, first over the STICS field of view, then over 3 hr intervals in the 9 hr about the shock. The averages, with errors assuming Poisson statistics, are then fitted using the Levenburg–Marquardt nonlinear least squares technique to two simple, observationally suggested functions arising from diffusive shock acceleration (DSA) formalism: a power law in E/Q with spectral index (model I), and a power-law with exponential rollover having a cutoff in E/Q (model II). The first result is a comparison of upstream spectral indices, e-folding energies, and normalization constants with corresponding downstream values. The second is a comparison of fitted spectral indices against those given by measured CfA shock compression ratios and a comparison of fitted e-folding energies with those given by measured ratios and shock normal angles, per DSA-derived predictions. There is additionally a comparison between fitted parameters given by the two functional forms. Little agreement is found with values given by DSA.

Simultaneous Occurrence of Electromagnetic and Quasi‐Electrostatic Magnetosonic Waves

AbstractMagnetosonic (MS) waves usually manifest as electromagnetic fluctuations, while quasi‐electrostatic magnetosonic (QEMS) waves have been recently reported. Here we present an intriguing coexistence of low harmonic electromagnetic magnetosonic (EMMS) waves and QEMS waves within the same band. Ion Bernstein instabilities are calculated based on the observed proton distribution. Effective growth rates can occur in the first‐fourth harmonic bands with a broad wave number range when the wave normal angle is sufficiently large. In each harmonic band, the MS waves would transform from electromagnetic to electrostatic as the wave number increases. This study reveals that the simultaneous occurrence of EMMS and QEMS arises from the expansive excitation range of MS waves in ‐space, thereby implying the potential resonant interactions between MS and particles in a broad energy spectrum.

Midterm clinical and radiological outcomes of arthrogryposis-associated clubfoot treated with the Ponseti method: a retrospective observational study and comprehensive literature review

BackgroundThe treatment results of the Ponseti method for arthrogrypotic clubfoot have been described in only a few case series. Further evaluations are necessary.MethodsChildren from two German paediatric orthopaedic hospitals with arthrogryposis-associated clubfoot treated with the Ponseti method between 2004 and 2011 and who were at least five years of age at their last follow-up were retrospectively evaluated. The endpoints were the clinical foot position, necessary surgeries during the follow-up period and radiological constellations. A comprehensive literature review was conducted after a systematic literature search.ResultsSeventeen patients (47% with amyoplasia [AP] and 53% with distal arthrogryposis [DA]) met the inclusion criteria. Thirty-one feet were evaluated. The period between the treatment start and the last follow-up examination covered 8.9 ± 2.5 years. After the last cast removal within the initial Ponseti cast series, 74% of the clinical results were good to excellent. However, the clinical outcomes in the patients with AP were significantly worse. Overall, in 23 feet (74%), at least one major surgery at the age of 2.9 ± 2.2 years was necessary during the clinical course. Major surgeries were much more frequent on the feet of the patients with AP than with DA. Lateral X-rays showed normal age-appropriate radiological angles in 4% of the feet, hindfoot equinus in 19%, under-corrected hindfoot in 44%, under-corrected clubfoot in 26% and rocker bottom deformity in 7%. The radiological residual deformities in AP were much more severe than in DA (p = 0.042). Most of the studies reviewed (11 case series, 144 patients) reported high initial clinical correction rates, followed by high recurrence rates and the need for further surgeries.ConclusionAbout a quarter of the arthrogrypotic patients benefited from the Ponseti therapy without further major surgery. However, the clinically observed high initial correction rate after Ponseti therapy of arthrogrypotic clubfoot was not accompanied by a correction of the bony foot position in the X-rays. The feet of the patients with DA had better outcomes than those of the patients with AP. Therefore, in outcome studies, a clear distinction between patients with AP and those with DA is necessary.

Mathematical model and generation analysis for crossed helical gear system

Purpose Crossed helical gears have point contact and their surfaces are subject to high surface stress. Contact stress and root tooth stress are the most common sources of failure in crossed helical gear. This paper aims to study the load-carrying capacity and performance of crossed helical gear teeth with different gear tooth profiles. To overcome defects and reduce the sensitivity to small shaft angle changes. The combined tooth profile is designed to reduce the bending stresses, contact stresses and tooth deflection, and prevent pinion failure in the gearbox. Design/methodology/approach The principle of the method is a line contact is introduced instead of a point contact between two teeth in mesh with each other. The tooth surface of the helical gear is designed and cut by a modified tool. Higher normal pressure angles like 25° and 35° are used. The modified involute is accomplished to eliminate interference between the teeth. Engineering software packages have been applied to generate all crossed helical gears gear profiles. The modification is compounding curves consisting of an epicycloid-involute-hypocycloid gear teeth profile generated by the cutter modified. Findings The stresses in the crossed helical gear teeth profile were reduced by increasing the normal pressure angle values. Using a 35° pressure angle the enhancement percentage in contact stress and teeth fillet region will be about 29.345% and 15.421%, respectively. The best enhancement in a gear’s resistance is the epicycloid-involute-hypocycloid gear teeth profile. The enhancement was 32.610% and 18.588%. The skew in line of action in skewed helical gear will be sensitive when the crossing angles are small. Their teeth surface tends to be easily worn out; however, the wearing process will be reduced by using a proposed gear teeth profile. Practical implications The gear teeth to be modified are cut by a shaper process. The modifying rack cutter of this study can be used as a reference for creating a different helical gears sample. The helical teeth surface is modified to become an envelope of the other. This makes an original point contact change into a line contact. The epicycloid-involute-hypocycloid gear teeth profile is preferred for a higher contact ratio and a large load capacity. This work explicitly introduces a new method of kinematic consideration to improve the load capacity of crossed helical gear. Originality/value This paper showed some novel results by the unique shape of the rack-cutter designed to generate different helical angles and different gear positions. In the future, it will make valuable contributions to the further development of the dynamic performance of a crossed helical gear system through the study in the field of using asymmetric teeth profiles of helical gears with tip relief as the manner to enhance the crossed helical gear performance. Investigation of crossed helical gear by applying a predesigned parabolic function of transmission error enables the absorption of linear discontinuous functions caused by misalignment.

Research on the Magnetorheological Finishing Technology of a High-Steepness Optical Element Based on the Virtual-Axis and Spiral Scanning Path.

Magnetorheological finishing (MRF) of aspherical optical elements usually requires the coordination between the translational axes and the oscillating axes of the machine tool to realize the processing. For aspheric optical elements whose steepness exceeds the machining stroke of the equipment, there is still no better method to achieve high-precision and high-efficiency error convergence. To solve this problem, an MRF method combining virtual-axis technology and a spiral scanning path is proposed in this paper. Firstly, the distribution law of the magnetic induction intensity inside the polishing wheel is analyzed by simulation, the stability of the removal efficiency of the removal function within the ±7∘ angle of the normal angle of the polishing wheel is determined, and MRF is expanded from traditional single-point processing to circular arc segment processing. Secondly, the spiral scanning path is proposed for aspherical rotational symmetric optical elements, which can reduce the requirements of the number of machine tool axes and the dynamic performance of machine tools. Finally, an aspherical fused silica optical element with a curvature radius of 400 mm, K value of -1, and aperture of 100 mm is processed. The PV value of this optical element converges from 189.2 nm to 24.85 nm, and the RMS value converges from 24.85 nm to 5.74 nm. The experimental results show that the proposed combined process has the ability to modify curved optical elements and can be applied to ultra-precision machining of high-steepness optical elements.

Ultrablack surface with omnidirectional high absorption.

Black surface plays an important role in solar-thermal conversion systems and space optical systems. Despite the significant efforts in developing a black surface with strong broadband absorption, realizing scalable omnidirectional high absorption ultrablack surfaces remains challenging. Here, we report an ultrablack surface based on a structural black paint (SBP), realized by femtosecond (fs) laser fabrication of high aspect ratio microstructure mold followed by mold transferring on black paint coating. The SBP exhibits extremely low hemispheric reflectance (R < 1.2%) in the solar spectrum at a normal incident angle; even at an 80° incident angle, the SBP also has good anti-reflection performance (R < 9%). Based on such properties, we further show the enhanced solar-thermal performance over commercial black paints. Our approach holds promises for scalable and cost-effective manufacturing of ultrablack surface, with potential applications in solar-thermal conversion efficiency improvement and space optical system stray light suppression.

In Vivo Assessment of the Pediatric Trabecular Meshwork, Schlemm Canal, and Iridocorneal Angle Using Overhead-Mounted Optical Coherence Tomography

PurposeTo describe the in vivo morphologic characteristics of the trabecular meshwork (TM), Schlemm canal (SC), and iridocorneal angle in pediatric patients with normal eyes, glaucoma and cataract. DesignProspective cohort study Study population70 eyes (41 children) were enrolled. 28 normal eyes, 19 eyes with glaucoma, and 26 eyes with cataract (15 pre-, 11 post-lensectomy). Average age was 2.8±3.0 years at imaging. MethodsPediatric patients undergoing clinically indicated examination under anesthesia underwent overhead-mounted optical coherence tomography (OCT) imaging of the outflow pathway. Images were then evaluated for abnormalities in the outflow pathway. Main outcome measurePresence of thickened TM, SC patency, any iridocorneal angle malformation, and episcleral vessel patency in normal eyes vs. all other eyes. ResultsThickened TM tissue was found in no normal eyes, 47.4% of eyes with glaucoma, and 53.8% of eyes with cataracts. A patent SC was demonstrated in all normal eyes, 32% with glaucoma, and 65.4% with cataracts. Iridocorneal angle abnormality was identified in no normal eyes, 94.7% with glaucoma, and 69.2% with cataracts. Prevalence of iridocorneal angle abnormality was similar in cataract eyes pre- and post-lensectomy. All but one eye with glaucoma secondary to anterior segment dysgenesis had patent episcleral vessels. Intraocular pressure (IOP) at imaging was lower in eyes with than without a patent SC (13.9±3.8mmHg vs. 28.2±11.7mmHg, p<0.001). IOP was lower in eyes with normal iridocorneal angles compared to those with angle malformation (13.9±3.2mmHg vs. 22.6±12.1mmHg, p<0.001). There was no significant difference in IOP between eyes with normal TM thickness compared to those with thickened TM (17.4±8.2mmHg vs.17.4±9.5mmHg, p = 0.943). ConclusionEyes of children with glaucoma demonstrated thickened TM, decreased patency of SC, and abnormalities of the iridocorneal angle on OCT imaging, compared to normal controls. These abnormal findings also appear in many pediatric eyes with cataracts, even prior to lensectomy. Future study is warranted to evaluate the role these structural differences may play in the development of glaucoma following cataract surgery and the significant variation in how individual glaucoma eyes respond to angle surgery.

Prevalence and Propagation of Lightning‐Generated Whistlers in Van Allen Probes EFW Burst Data

AbstractWe assess the prevalence of ducted and non‐ducted whistler propagation using burst mode data from the Van Allen Probes Electric Field and Waves instrument (EFW). We have identified burst periods containing lightning‐generated whistlers (LGWs), resulting in a data set available for future use. The entire burst data set is filtered through an analysis of the search coil magnetometer (SCM) noise, identifying signals in frequency space that exceed an adaptive noise threshold. We implement DBSCAN (Density‐Based Spatial Clustering of Applications with Noise) to identify individual whistlers and clusters of whistlers. With magnetic spectral analysis, we calculate the mean wave normal angle (WNA) for each LGW group. We use ray tracing to estimate the expected WNA distributions for non‐ducted LGWs to compare to the data and determine methods for identifying potentially ducted LGWs. The ray‐tracing results provide a clear threshold in WNA for ducted whistlers. Using this threshold, we estimate that at least of LGWs in this data set are ducted. We find that the majority of potentially ducted whistlers are below and nearly half of LGWs below and within 9–18 MLT may be ducted.

Relationship between interincisal angles and TMJ morphology/position and trabecular structure: a retrospective study

BackgroundTMJ morphology/position and trabecular structure are influenced by various factors. The role of the interincisal angle, an indicator of the anterior occlusal relationship, on TMJ remains unclear. This study aims to investigate the morphology, trabecular bone structure, and position of the condyle, as well as the glenoid fossa’s morphology in skeletal class II populations with different interincisal angles.Materials and methodsA total of 150 adult patients with normodivergent facial types and skeletal class II malocclusions were selected and divided into three groups based on their interincisal angles: normal, small, and large angle groups. The indexes of TMJ were measured using cone-beam computed tomography (CBCT) data and analyzed using Dolphin Imaging, Mimics, and ImageJ.ResultsThe small angle group had the smallest anteroposterior diameter (APD), while the large angle group had a greater mediolateral diameter (MLD). The large angle group exhibited significantly the largest maximum axial area, bone surface area, and bone volume (P < 0.05). Small and large angle groups exhibited greater bone trabeculae (Tb. N) and thinner trabecular thickness (Tb. Th). Compared to the normal angle group, the small angle group exhibited a larger horizontal condylar angle and smaller bilateral condylar angles on the axial plane, while the large angle group showed the opposite trend. Small and large angle groups showed a reduced vertical condyle angle on the coronal plane, with the largest reduction observed in the large angle group (P < 0.05). Small and large angle groups had higher heights of the glenoid fossa (GFH). The large angle group exhibited the greatest GFH and width of the glenoid fossa (GFW) (P < 0.05).ConclusionThe large angle group had elongated oval and large condyles, and deeper glenoid fossae, while a flattened-oval and smaller condyle, and wider and shallower glenoid fossae were observed in the small angle group. Small and large interincisal angle affects the structure of condylar trabeculae, resulting in thinner Tb. Th and greater Th. N. In the condylar position, small and large angle groups exhibit condylar rotation in the axial and coronal planes. Therefore, the interincisal angle affects the morphology, position, and trabecular structure of the TMJ. This implies that we must pay attention to the impact of the interincisal angle on TMJ, and it is crucial to restore the normal interincisal angle during orthodontic treatment.

Modeling and verification of cortical bone drilling forces based on tissue structure heterogeneity

Bone drilling mechanism study is the basis for the optimization of cortical bone drilling process and drill geometry. In this paper, a drilling force model for modified drills with thinned chisel edge is established considering the heterogeneous structure of cortical bone. The bone mineral density is embedded into the established model, the model can predict the axial thrust force change along the drilling depth direction, and the model is verified through cortical bone drilling experiments. The thrust force and torque predicted by the model are in good agreement with the drilling experimental results of cortical bone drilling. Then, the drilling performance of the modified drill and the common drill is compared through cortical bone drilling experiments. Compared with common drill bits, the maximum reduction in average thrust force of the modified drill bit during stable drilling is 21.21 % (n = 2500 rpm, Vf=60 mm/min). The maximum reduction in average roughness of the hole wall is 21.87 % (n = 500 rpm, Vf=10 mm/min). The drill chisel edge thinning design reduces the negative impact of the negative normal rake angle on the cutting lip of common drill on drilling force and stability. Therefore, the drill bit chisel edge thinning design can effectively improve the drilling performance.

Determining the normal range of the calcaneus-metatarsal angles in the second-trimester fetal ultrasound examination using the novel measurement technique "Melek's angles": A cross-sectional study.

The aim of this study is to establish the normal calcaneus-metatarsal angles in order to facilitate the recognition of fetal foot deformities. Therefore, a novel measurement technique was determined using ultrasound and applied to nonanomalous fetuses in the 18th to 23rd gestational weeks. This cross-sectional study included 100 low-risk, nonanomalous fetuses in the 18th to 23rd weeks of gestation. Measurements were obtained using the novel measurement technique in fetal ultrasound examination. Fetal biometry, foot sole length, first and fifth metatarsal diaphyseal length measurements were taken. The acute angle measurement of the line segment passing between the calcaneus outer lateral and proximal fifth metatarsal with the long axis of the first metatarsal diaphysis (CA-mtt1) and long axis of the fifth metatarsal diaphysis (CA-mtt5) was taken. Interobserver and intraobserver reliabilities were assessed by intraclass correlations (ICC). A strong positive correlation was detected between bi-parietal diameter (BPD) and foot sole length, first metatarsal diaphyseal length and fifth metatarsal diaphyseal length (p < 0.0001). No significant correlation of these CA-mtt1 and CA-mtt5 angles with BPD was detected (p = 0.35, p = 0.82, respectively). The data suggest that the CA-mtt1 and CA-mtt5 angles remained consistently within a narrow range and were determined to be 20.0° ± 8.7° and 7.8° ± 7.5°, respectively. Intraobserver and interobserver agreement for CA-mtt1 angle was moderate (ICC, 0.655) and moderate (ICC, 0.615), for CA-mtt5 angle was moderate (ICC, 0.631) and moderate (ICC, 0.605), respectively. A normal reference range was established for fetal sole length, first metatarsal diaphysis length, fifth metatarsal diaphysis length, CA-mtt1 angle, and CA-mtt5 angle in the 18th to 23rd weeks of gestation. It was determined that the CA-mtt1 and CA-mtt5 angles remained relatively constant within a narrow range throughout the assessed gestational weeks.

A Parametric Study of Locally Generated Magnetosonic Waves by Ring‐Beam Hot Protons in the Martian Heavy Ion‐Rich Environment

AbstractMagnetosonic (MS) waves with frequencies above the proton gyrofrequency can be locally generated by ring‐beam protons in the Martian heavy ion‐rich ionosphere. In this study, we conduct a parametric analysis to investigate the effects of heavy ion concentrations, energy (Erb), and angle (αrb) of ring‐beam protons, and wave normal angle on the excitation features of Martian ionospheric MS waves. We find the growth rates and frequency range of MS waves decrease by including O+ and O2+ ions but are insensitive to their relative concentrations. With increasing Erb or αrb, the growth rates of MS waves show a general dropping tendency. Meanwhile, their frequency and wavenumber range are almost unaffected by increasing Erb but shrink to a narrower range mainly distributed in high frequencies by increasing αrb. Unstable MS waves expand to a wider wavenumber range but shrink to a narrower frequency range as they become more oblique.

Gastric perforation as a complication of Wilkie's syndrome.

Wilkie's syndrome, also known as Superior mesenteric artery (SMA) syndrome, is characterized by intestinal obstruction due to aortomesenteric duodenal compression caused by the reduction of the normal angle between (38-65º) to <25º or to a distance <8mm. The clinical presentation is usually non-specific (dyspepsia, postprandial abdominal pain) but sometimes presented as an acute intestinal obstruction syndrome (nausea, vomiting, gastric dilatation and abdominal distention). In this study, we report the case of a 22-year-old patient with a BMI of 16.5 who presented to the emergency room with acute intestinal obstruction caused by SAMS. He presented with massive gastric dilation that caused ischaemic necrosis of the gastric mucosa with subsequent perforation. It should be noted that only one case associated with Wilkie syndrome has been described in the literature. Therefore, given the rare incidence of complications associated with this syndrome and the favourable prognosis with conservative management, surgery is usually the last line of treatment. However, we must not forget that when necrosis appears, it is often extensive and requires urgent surgical treatment in most cases.

TO STUDY THE FUNCTIONAL AND RADIOLOGICAL OUTCOMES OF ANKLE ARTHRODESIS WITH CORTICOCANCELLOUS SCREW FIXATION VS INTRAMEDULLARY NAILING

Objective: We aimed to evaluate the functional and radiological outcomes of ankle arthrodesis using corticocancellous screw fixation vs intramedullary nailing. Methods: In our study, 22 cases underwent the procedure. This evaluation was performed based on preoperative radiologic data and at postoperative clinical visits at 2 months, 6 months, and 12 mo required postoperatively. Radiologic outcomes were measured by: (1) Rate of union, (2) Rate of adjacent joint arthritis, and (3) Alignment of the ankle joint. Functional outcomes were measured by using the AOFAS score (American Orthopedic Foot and Ankle Society score). The patients' Subjective assessments were done using the Cumberland Ankle Instability Tool (CAIT). Results: The angle between the tibia's long axis and a line parallel to the talus's long axis is determined in the AP projection. The mean angle was 89.6 degrees (85-100 degrees) in the intramedullary nailing group (IMN group) and 91.4 degrees in the corticocancellous screw group (CC screw). The angle between the tibia's long axis and a line that is perpendicular to the talus’s long axis. The mean angle was 40.5 degrees (30-45 degrees) in the IMN group and 41.6 degrees in the CC screw group. The mean AOFAS score (American Orthopedic Foot and Ankle Society score) was 83.25 in the IMN group and 80.5 in the other group. The mean Cumberland Ankle Instability Tool (CAIT) score was 28 in the IMN group and 27.5 in the other group. All the cases showed bony union except one case, the average time taken for the union was 18.5 w in the IMN group and 20.5 w in the CC screw group. Conclusion: According to our study, all of the patients with normal angles between the tibia's long axis and a line perpendicular to the talus's long axis were obtained in the AP projection, and the angle between the tibia's long axis and a line that is perpendicular to the talus’s long axis. These patients also showed better Cumberland Ankle Instability Tool (CAIT) and AOFAS (American Orthopedic Foot and Ankle Society) scores in both comparison groups.

A practical solution to improve the field of view in circular scanning-based photoacoustic tomography.

One of the primary challenges in ring single-element photoacoustic tomography systems is the low image quality in areas away from the center of the ring. This is mainly due to the limited field of view (FOV) of each transducer, which in turn reduces the imaging FOV. To address this shortcoming, we have put forward a practical and straightforward solution to enhance the FOV of circular scanning-based photoacoustic tomography (CS-PAT). This is accomplished by placing transducers at different angles instead of using a single transducer placed at a normal angle to the imaging target. We also modified the ring scanner inner wall surface to significantly reduce photoacoustic reverberation. By imaging several phantoms, we show a significant improvement in the images generated by our system imaging from 4.1 to over 7 for the signal-to-noise ratio and structural similarity index increased from 41% to 70%.

OCT Angiography of the Retina and the Choroid in the Macula in Patients with Normal Tension Glaucoma and Primary Open Angle Glaucoma.

The aim of this study was to compare vessel density (VD) in the retina and choroid in eyes with primary open angle glaucoma (POAG), normal tension glaucoma (NTG) and controls. Patients with POAG, NTG and controls underwent OCT scanning of the macula and the disc followed by 6 × 6 mm macula OCT angiography (OCTA) imaging. Global and hemifield VD were recorded for the superficial (SVP) and deep (DVP) vascular plexus and the choriocapillaris (CC). The OCT thickness of the nerve fiber layer (NFL) and ganglion cell layer (GCC) was also measured. Data from 65 POAG, 33 NTG and 40 control eyes matched for age were analyzed. Mean SVP VD was lower in NTG and POAG eyes compared to controls (38.8 ± 5.3, 40.7 ± 6.8 and 48.5 ± 4.0%, p < 0.001). Mean DVP VD was lower in NTG and POAG eyes compared to controls (43.1 ± 6.1, 44.5 ± 7.6 and 48.6 ± 5.8%, p = 0.002). There was no difference in SVP VD or DVP VD between the glaucoma groups (p > 0.050). No difference was noted in CC VD between the groups (68.3 ± 2.3, 67.6 ± 3.7 and 68.5 ± 2.6%, p = 0.287). Lower SVP and DVP VD was seen in eyes with glaucoma compared to normal eyes. NTG and POAG eyes had similar VD loss. Eyes with glaucoma manifested similar CC VD compared to controls.