Changes In Geometry Research Articles

Impact of Vehicle Engine Supply System on In-Service Changes in Body Geometry and Wheel Alignment

Impact of Vehicle Engine Supply System on In-Service Changes in Body Geometry and Wheel Alignment

Acute changes in right ventricular geometry and function following transcatheter tricuspid valve interventions

Abstract Background Little is known about acute changes in right ventricular (RV) function and geometry following transcatheter tricuspid edge-to-edge repair (T-TEER) or transcatheter tricuspid valve replacement (TTVR). Pressure-strain-volume loop-derived myocardial work metrics showed associations with myocardial energetics and contractility in conditions accompanied by volume overload, suggesting their potential utility in patients with tricuspid regurgitation (TR). Purpose To define acute changes in RV volumes and RV myocardial work following T-TEER and TTVR using conventional and pressure-strain-volume derived RV work metrics. Methods In this multicenter, observational study, 3D echocardiographic datasets and invasively acquired RV pressures were collected before and after transcatheter tricuspid valve procedure. Using dedicated software (ReVISION, Argus Cognitive) 3D RV volumes and strains were quantified and decomposed to longitudinal, radial and anterio-posterior motion. Forward stroke volume (SV) was calculated by subtracting TR volumes from RV 3D end-diastolic volume (EDV) and end-systolic volume (ESV) difference. Three-dimensional pressure-strain-volume loops were constructed and global RV work-index (RV-Wi) was calculated. Changes in RV parameters before and after the intervention were compared using paired-samples t test. Results Of 37 patients included in this study (65% male), 20 underwent T-TEER and 17 underwent TTVR. Compared to T-TEER patients, patients undergoing TTVR had higher prevalence of torrential TR at baseline but also achieved a higher reduction in TR volumes after the intervention (44 ± 11 ml vs 60 ± 16ml; p = 0,001). Following T-TEER there was a significant reduction in RV EDV (240 ± 93 ml vs 200 ± 80 ml; p < 0.001) and increase in SV (55 ± 34 ml vs 68 ± 26 ml; p = 0.036). Following TTVR there was a significant increase in RV ESV (121 ± 46 vs 146 ± 48, p = 0.003) and no significant change in SV (47 ± 24 ml vs 55 ± 20 ml; p = 0.143). There was significant reduction in RV strain and ejection fraction (EF) (all p < 0.001) primarily driven by reduction of radial motion component in both groups. RV-Wi increased in 35% (7/20) of T-TEER patients and in 18% of (3/17) TTVR patients. Conclusion An acute reduction in RV EF was observed in all patients and was mainly caused by decrease in RV EDV in T-TEER patients and increase in RV ESV in TTVR patients. Despite decrease of conventional metrics of RV function in both groups, an increase in RV-Wi was observed in 27% of all patients.Baseline and follow-up characteristicsCentral Figure

Long-term changes in cardiac geometry and mechanics after bariatric surgery- insights from the FatWest study

Abstract Background Patients with severe obesity have a high prevalence of subclinical cardiac organ damage including impaired longitudinal and radial cardiac mechanics. Previous studies on the impact of bariatric surgery on cardiac remodeling, most of them with short patient follow-up, have yielded inconsistent results. Purpose To assess progressive changes in cardiac geometry and mechanics up to five years following bariatric surgery. Methods In the prospective Bariatric Surgery on the West Coast of Norway (FatWest) study, cardiac remodeling was assessed by 2D echocardiography preoperatively and at six months, one year and five years after Roux-en-Y gastric bypass in a cohort of 97 patients (44±10 years, 72% women, body mass index [BMI] 41.8±4.8 kg/m²). Excess weight loss (EWL) was calculated as: absolute weight loss/(initial weight-ideal weight)x100. Left ventricular (LV) size was assessed by the LV mass/ height^2.7, LV longitudinal mechanics by the peak global longitudinal strain (GLS) and radial mechanics by the midwall shortening (MWS). LV myocardial oxygen demand was estimated from the LV mass-wall stress-heart rate product. Right ventricular diameter was measured in the basal one-third of the ventricular cavity. Left atrial (LA) reservoir function was assessed by the LA emptying fraction. Results After a mean follow-up of 63±13 months, the average postoperative EWL was 66%. Overall, both right ventricular diameter, LV mass index, LV GLS, myocardial oxygen demand and LAEF (68% vs. 64%) improved significantly at the 5-year follow-up (all p<0.05), while MWS remained unchanged (Figure). Prevalence of normal LV geometry increased gradually from 56% to 80%, while that of LV hypertrophy fell from 36% to 16% (p<0.001). Analyses of temporal trends showed that improvement in BMI, LV mass and LV GLS occurred during the first postoperative year (Figure). In Cox regression analysis, a low 5-year GLS was associated with preoperative hypertension after adjustment for age, sex, preoperative diabetes mellitus, and postoperative changes in BMI, mean blood pressure and myocardial oxygen demand (p<0.01). In a similar linear model, after adjustment for the same covariates, LV mass index at the 5-year follow-up was independently related to the magnitude of the postoperative BMI reduction (R² = 0.58, p<0.001). Conclusion Ventricular size and longitudinal mechanics are significantly improved 5 years after bariatric surgery, with the reverse remodeling occurring during the first postoperative year. Residual abnormal 5-year LV geometry and mechanics are related to preoperative hypertension and suboptimal BMI reduction.Figure

Impact of changes in left heart geometry on predicting new-onset atrial fibrillation in patients with hypertension

Abstract Background Hypertension-induced left ventricular hypertrophy (LVH) increases end-diastolic LV pressure and contributes to left atrial enlargement (LAE), which are associated with development of atrial fibrillation (AF). However, the impact of LVH and LAE and their regression following antihypertensive therapy on AF incidence remains unclear. Purpose This study aimed to investigate the impact of changes in the LVH and LAE status on the occurrence of new-onset AF (NOAF). Methods This retrospective analysis included patients with sinus rhythm who underwent echocardiography at hypertension diagnosis and after 6–18 months. LVH was defined as LV mass index >115 g/m2 (men) and >95 g/m2 (women), and LAE was defined as LA volume index >42 ml/m2. LVH and LAE regression was defined as the absence of LVH and LAE on follow-up echocardiography, respectively. The occurrence of NOAF was assessed in relation to changes in LVH and LAE status. Results Among the 1,464 patients included in the study, 163 (11.1%) patients developed NOAF during a median follow-up of 63.8 months (interquartile range, 35.9–128.5 months). On average, 12 electrocardiograms per patient were reviewed for AF detection. New-onset LVH (adjusted HR 1.88, 95% CI 1.20–2.94, P=0.006) and LAE (adjusted HR 1.89, 95% CI 1.05–3.40, P=0.034) were significant predictors of NOAF. Conversely, regression of LVH (adjusted HR 0.51, 95% CI 0.280.91, P=0.022) or LAE (adjusted HR: 0.30, 95% CI 0.15–0.63, P=0.001) after antihypertensive therapy was associated with a reduced risk of NOAF. The risk of NOAF was higher in patients with LVH and LAE together (adjusted HR 4.30, 95% CI 2.81–6.56, P<0.001) than in those with either LVH or LAE, or those with neither, as determined by follow-up echocardiography. Conclusion In patients with hypertension and sinus rhythm, regression of LVH and LAE following antihypertensive therapy is associated with a decreased incidence of NOAF, whereas newly developed LVH or LAE is associated with a higher risk of NOAF. The changes in left heart geometry can serve as a predictive marker for NOAF in patients with hypertension.

Physics-Informed Neural Networks for the Reynolds Equation with Transient Cavitation Modeling

Gaining insight into tribological systems is crucial for optimizing efficiency and prolonging operational lifespans in technical systems. Experimental investigations are time-consuming and costly, especially for reciprocating seals in fluid power systems. Elastohydrodynamic lubrication (EHL) simulations offer an alternative but demand significant computational resources. Physics-informed neural networks (PINNs) provide a promising solution using physics-based approaches to solve partial differential equations. While PINNs have successfully modeled hydrodynamics with stationary cavitation, they have yet to address transient cavitation with dynamic geometry changes. This contribution applies a PINN framework to predict pressure build-up and transient cavitation in sealing contacts with dynamic geometry changes. The results demonstrate the potential of PINNs for modeling tribological systems and highlight their significance in enhancing computational efficiency.

A novel framework for elucidating the effect of mechanical loading on the geometry of ovariectomized mouse tibiae using principal component analysis

IntroductionMurine models are used to test the effect of anti-osteoporosis treatments as they replicate some of the bone phenotypes observed in osteoporotic (OP) patients. The effect of disease and treatment is typically described as changes in bone geometry and microstructure over time. Conventional assessment of geometric changes relies on morphometric scalar parameters. However, being correlated with each other, these parameters do not describe separate fractions of variations and offer only a moderate insight into temporal changes.MethodsThe current study proposes a novel image-based framework that employs deformable image registration on in vivo longitudinal images of bones and Principal Component Analysis (PCA) for improved quantification of geometric effects of OP treatments. This PCA-based model and a novel post-processing of score changes provide orthogonal modes of shape variations temporally induced by a course of treatment (specifically in vivo mechanical loading).Results and DiscussionErrors associated with the proposed framework are rigorously quantified and it is shown that the accuracy of deformable image registration in capturing the bone shapes (∼1 voxel = 10.4 μm) is of the same order of magnitude as the relevant state-of-the-art evaluation studies. Applying the framework to longitudinal image data from the midshaft section of ovariectomized mouse tibia, two mutually orthogonal mode shapes are reliably identified to be an effect of treatment. The mode shapes captured changes of the tibia geometry due to the treatment at the anterior crest (maximum of 0.103 mm) and across the tibia midshaft section and the posterior (0.030 mm) and medial (0.024 mm) aspects. These changes agree with those reported previously but are now described in a compact fashion, as a vector field of displacements on the bone surface. The proposed framework enables a more detailed investigation of the effect of disease and treatment on bones in preclinical studies and boosts the precision of such assessments.

Impact of arterial system alterations due to amputation on arterial stiffness and hemodynamics: a numerical study

Subjects with amputation of the lower limbs are at increased risk of cardiovascular mortality and morbidity. We hypothesize that amputation-induced alterations in the arterial tree negatively impact arterial biomechanics, blood pressure and flow behavior. These changes may interact with other biological factors, potentially increasing cardiovascular risk. To evaluate this hypothesis regarding the purely mechanical impact of amputation on the arterial tree, we used a simulation computer model including a detailed one-dimensional (1D) arterial network model (143 arterial segments) coupled with a zero-dimensional (0D) model of the left ventricle. Our simulations included five settings of the arterial network: (1) 4-limbs control, (2) unilateral amputee (right lower limb), (3) bilateral amputee (both lower limbs), (4) trilateral amputee (lower-limbs and right upper-limb), and (5) quadrilateral amputee (lower and upper limbs). Analysis of regional stiffness, as calculated by pulse wave velocity (PWV) for large-, medium- and small-sized arteries, showed that, while aortic stiffness did not change with increasing degree of amputation, stiffness of medium and smaller-sized arteries increased with greater amputation severity. Despite a staged decrease in cardiac output, the systolic and diastolic blood pressure values increased, resulting in an increase in both central and peripheral pulse pressures but with an attenuation of pulse pressure amplification. The most significant increase in peak systolic pressure and decrease in peak systolic blood flow was observed at the site of the abdominal aorta. Wave separation analysis indicated no changes in the shape of the forward and backward wave components. However, the results from wave intensity analysis showed that with extended amputation, there was an increase in peak forward wave intensity and a rise in the inverse peak of the backward wave intensity, suggesting potential alterations in cardiac hemodynamic load. In conclusion, this simulation study showed that biomechanical and hemodynamic changes in the arterial network geometry could interact with additional risk factors to increase the cardiovascular risk in patients with amputations.

Syndrome Sinistre: Left Brachiocephalic Vein Compression and its Neurological Manifestations.

Embryologically, the left brachiocephalic vein (LBV) originates as an anastomotic channel between the right and left anterior cardinal veins. This positions the LBV between the manubrium sterni anteriorly and the innominate artery posteriorly. This pattern of adjacency of the aorta to the LBV is unique to mammals and results from a quirk of evolution. With age, the ascending aorta unfolds, elongates and dilates. Simultaneously, there is a change in the thoracic geometry that reduces the thoracic volume primarily from disc height loss and kyphosis. These transitions progressively compress the LBV. Normally, this compression is circumvented via collateral pathways and "Blood finds a way". However, traversing these circuitous pathways comes at a cost and can result in delayed transit times and venous congestion. While it is possible that compression of the LBV in the setting of adequate collateral channels may fail to provoke any pathologic sequelae, we propose a phenomenon in which such compression in the setting of inadequate collateral circulation may lead to a state of pathologic venous congestion. This anatomic anomaly and its associated clinical features, if identified, can offer a new avenue for treatment options for some of the hitherto unexplained neurologic disorders.

Deformed alluvial terraces record an excess of slip over the last few centuries on the Himalayan Topographic Frontal Thrust of central Bhutan

Deformed alluvial terraces are ubiquitous markers of a fault’s recent activity and may help assess its slip rate and associated seismic hazard. They are often considered as a nearly flat surface translated and rotated along a planar or listric fault. The present study challenges these assumptions by revealing uneven terrace treads and verticalization of the Topographic Frontal Thrust (TFT) in south-central Bhutan. We model this finding as combined variability in both the aggradation and geometry of the TFT. We estimate a Holocene slip rate of 19.6 ± 4.1 mm.yr−1, which confirms that the TFT accommodates most of the shortening across the range. Contrary to previous studies, we find an excess of slip over the last few centuries, which implies a lower seismic hazard. These results highlight the importance of considering the non-planar component in terrace shape, shallow abrupt changes in fault geometry, and aggradation in future morphotectonic studies worldwide.

TriHuman: A Real-time and Controllable Tri-plane Representation for Detailed Human Geometry and Appearance Synthesis

Creating controllable, photorealistic, and geometrically detailed digital doubles of real humans solely from video data is a key challenge in Computer Graphics and Vision, especially when real-time performance is required. Recent methods attach a neural radiance field (NeRF) to an articulated structure, e.g., a body model or a skeleton, to map points into a pose canonical space while conditioning the NeRF on the skeletal pose. These approaches typically parameterize the neural field with a multi-layer perceptron (MLP) leading to a slow runtime. To address this drawback, we propose TriHuman a novel human-tailored, deformable, and efficient tri-plane representation, which achieves real-time performance, state-of-the-art pose-controllable geometry synthesis as well as photorealistic rendering quality. At the core, we non-rigidly warp global ray samples into our undeformed tri-plane texture space, which effectively addresses the problem of global points being mapped to the same tri-plane locations. We then show how such a tri-plane feature representation can be conditioned on the skeletal motion to account for dynamic appearance and geometry changes. Our results demonstrate a clear step toward higher quality in terms of geometry and appearance modeling of humans as well as runtime performance.

ТЕОРЕТИЧНЕ ДОСЛІДЖЕННЯ ТЕПЛОВИХ ПРОЦЕСІВ НА ВУГЛЕЦЕВИХ ЕЛЕКТРОДАХ В РЕЗУЛЬТАТІ ДІЇ ПЛАЗМИ ПРИ ГЕНЕРАЦІЇ НАНОСТРУКТУР У ВАКУУМНІЙ ДУЗІ

A mathematical model has been refined to determine the thermophysical and thermomechanical processes on electrodes during the plasma formation of nanostructures. The model takes into account the effects of electrode spots, evaporation, sputtering, and thermal stresses in the electrode bodies. Calculations of temperature distribution on the surfaces of the graphite cathode and anode were carried out, considering the conditions necessary for obtaining nanostructures. An analysis of the thermophysical processes on the surfaces of the graphite cathode and anode during the transition to the working regime was conducted. The stability of the electrodes during plasma generation of nanostructures was determined by changes in the geometry of the electrodes. Calculations of the temperature fields on the end surface of the graphite cathode showed that with a continuous increase in the cathode surface temperature, the nature of its distribution does not change fundamentally. Calculation of temperature fields along the radius of the graphite cathode at different moments in time during the transition to the working regime showed a slight impact of evaporation on the change in the cathode's geometry. Determining the temperature fields along the generatrix of the anode showed the greatest impact of evaporation on the small area of the anode closest to the cathode. The dependencies of the acting stresses on temperature for the graphite cathode and anode were obtained. Studies of the dynamics of changes in thermal stresses on the electrodes during the formation of nanostructures in a plasma environment indicate that the values of thermal stresses are far from the material's strength limit. A theoretical study of the thermophysical and thermomechanical processes on the graphite cathode was carried out and compared with experimental measurements. The calculation of the electrodes' lifespan during the creation of carbon nanostructures in a plasma environment was 2.52∙105 s. The experimental lifespan of the graphite cathode is 2.88∙105 s, which is quite close to the calculated value. The coincidence of the obtained theoretical and experimental results indicates the viability of the developed model. The article may be of interest when designing equipment for obtaining nanostructures in a plasma environment and for further research on the physical parameters of electrodes.

Variable Geometry Turbine Turbocharger Optimization Using Machine Learning for On-Highway Fuel Cell Applications

<div>Turbocharger design involves adjustment of various geometric parameters to improve the performance and suit mechanical constraints, depending on the application-specific requirements. In designing the turbine stage, these parameters are optimized to maximize durability and efficiencies at the required operating points. For a heavy-duty class eight truck, “road load” and “rated power” are generally considered the two most important operating points. The objective of this article is to improve the efficiencies of these two operating points.</div> <div>The common challenge in the development of a turbine wheel design is the large number and interdependence of parameters to optimize. For example, increasing the blade thickness improves structural strength but reduces the mass flow capacity, thus influencing its performance. It is general practice to optimize the wheel geometry using iterative CFD analysis. However, running simulations for every single change in geometry involves significant computation time and does not guarantee the global optimum.</div> <div>This study proposes a machine learning (ML)-driven optimization process for variable turbine geometry (VTG) wheels with two target operating points. Initial CFD data is collected and used to train/validate a ML model for each operating point. A multi-objective optimization algorithm utilizes these ML models to provide a list of ideal turbine wheel designs, and the best candidates are validated in CFD for accuracy. The results are a balanced maximization in efficiency for both operating points, with an improvement in the pareto front by 1.4% points over CFD optimization alone.</div>

Study on Flexural Performance of Reinforced Concrete Beams Strengthened with FRP Grid–PCM Composite Reinforcement

To study the flexural performance of fiber-reinforced polymer (FRP) grid–polymer cement mortar (PCM)-composite-strengthened RC beams, the finite element numerical simulation of FRP grid–PCM composite RC beams is carried out using ABAQUS to analyze the effects of the amount of FRP grid reinforcement, the type of FRP grid material, and the geometry of FRP grid on the flexural performance of reinforced concrete beams and to establish the flexural capacity calculation formula of FRP grid–PCM-reinforced RC beams in case of debonding failure, based on analysis of the influencing factors. The results show that increasing the reinforcement of the FRP grid and increasing the stiffness of the FRP grid can improve the flexural bearing capacity of RC beams, and the change of FRP grid geometry has little effect on the flexural bearing capacity of RC beams. The established formula for calculating the flexural bearing capacity of FRP grid-reinforced concrete beams can better predict the flexural capacity of reinforced concrete beams under peeling failure.

Surgical dissection of ignition behavior of aluminum nanoparticles using molecular dynamics

Aluminum nanoparticles (ANPs) show great promise in energy technology, yet their atomic behavior during ignition remains a puzzle. This study provides insights into atomic migration processes within ANPs of different chemical layers during ignition and combustion, inspired by surgical peeling techniques. The research reveals that cavity formation in ANPs is inevitable due to disparities in atomic migration rates between core and surface areas, with core aluminum atoms experiencing sudden and significant stress alterations crucial for cavity formation. A linear trend in atom counts across radial layers correlates with particle geometry, influencing reactivity and morphological changes. The proposed Bond Environment Change (BEC) analysis reveals that oxygen atoms in the ANP shell undergo a three-phase evolution: intensive bonding, gradual relaxation, and stable configuration, reflecting the dynamic transformation of the oxide layer during the reaction process. While this research provides a deeper understanding of ANP ignition and combustion mechanisms, it may serve as a reference for refining ANP synthesis and guiding further inquiries in the field of nanoparticle-based energy technologies.

Axial length association with corneoscleral sagittal height and scleral asymmetry.

To determine how corneoscleral geometry changes with axial length and to assess the usefulness of including the sagittal configuration of the anterior segment when predicting the axial length. An observational study was performed including 96 healthy subjects (96 eyes). Axial length was calculated from optical biometry (IOL Master 500). Corneal curvature and scleral sagittal height parameters at 13, 14 and 15 mm were obtained automatically using corneoscleral topography (eye surface profiler; ESP). In addition, corneal and scleral sagittal heights at numerous locations (21 radii: 0-10 mm from the corneal apex at 12 angles: 0-330°) were calculated using the raw height data extracted from the ESP. The relationships between axial length and the study parameters were analysed using Pearson correlation analysis. The equations for the prediction of axial length were obtained by fitting multiple linear regression models. The temporal-nasal scleral asymmetry at 13-, 14- and 15-mm chord lengths was significantly correlated with axial length (r2 ≤ 0.26; p < 0.001). Significant inverse correlations were found between the temporal scleral sagittal height and axial length (r2 ≤ 0.28; p ≤ 0.02). The nasal scleral sagittal height was not associated with axial length. Three significant multiple linear regression models were fitted based on spherical equivalent, corneal radius and scleral asymmetry at 13 (r2 = 0.79; p < 0.001), 14 (r2 = 0.80; p < 0.001) and 15 (r2 = 0.80; p < 0.001) mm chord lengths. Larger ocular globes show reduced temporal-nasal scleral asymmetry, mainly due to the lower sagittal height of the temporal sclera. Thus, the geometry of the temporal scleral may be a factor of interest during myopia progression.

PDOC-05 MULTIPLE ISOCENTRE VMAT PLANNING FOR PAEDIATRIC CRANIOSPINAL IRRADIATION USING THE HALCYON LINEAR ACCELERATOR

Abstract Paediatric brain tumours constitute the leading cause of cancer specific deaths worldwide. Many patients require craniospinal irradiation (CSI), one of the most technically demanding techniques in radiotherapy. Many LMIC centres have installed Varian Halcyon® linear accelerators and require a technique to execute CSI safely. This study evaluates a multiple isocentre VMAT planning strategy for CSI. The Halcyon is a ring based linac with a single 6MV flattening filter free (FFF) photon beam, a stacked and staggered double MLC for beam shaping and modulation, and no movable collimator jaws. Multiple isocentres are required for treatment fields longer than 28 cm. Paediatric CSI requires dose to be delivered to the entire thecal sac incorporating whole brain as well as entire spinal cord, resulting in long planning target volumes. In addition to the length of the treatment field, CSI treatments are complex due to the change in geometry of the target and the patient body over the length of the treatment field. Traditional 3D conformal radiotherapy techniques (3DCRT) require multiple isocentres with field matching and junction feathering. VMAT offers an alternative, but also require multiple fields to achieve coverage. A Halcyon based three isocentre VMAT technique was investigated and evaluated according to the QUANTEC criteria. Portal dosimetry quality assurance was performed on all fields to ensure they were clinically deliverable. High quality paediatric CSI VMAT treatments can be delivered on the Halcyon, using three isocentres with automatic feathering applied in field overlap regions. Two full arcs and one support arc were used for the brain area, with two posterior partial arcs per spine isocentre, each covering a total of 140 degrees posteriorly to limit integral dose and dose to the lungs and kidneys. Imaging and setup is required for every isocentre further than 8cm/10cm (Halcyon V2/V3 respectively) from the previous isocentre.

Transcriptional regulation of postnatal aortic development

The aorta exhibits tremendous changes in geometry, composition, and mechanical properties during postnatal development. These changes are necessarily driven by transcriptional changes, both genetically programmed and mechano-responsive, but there has not been a careful comparison of time-course changes in the transcriptional profile and biomechanical phenotype. Here, we show that the greatest period of differential gene expression in the normal postnatal mouse aorta occurs prior to weaning at three weeks of age though with important evolution of many transcripts thereafter. We identify six general temporal patterns, including transcripts that monotonically decrease to lower or increase to higher steady state values as well as those that either peak or dip prior to or near weaning. We show that diverse transcripts within individual groupings correlate well over time, and that sub-sets of these groups correlate well with the developmental progression of different biomechanical metrics that are expected to be involved in mechano-sensing. In particular, expression of genes for elastin and elastin-associated glycoproteins tend to correlate well with the ratio of systolic-to-diastolic stress whereas genes for collagen fibers correlate well with the daily rate of change of systolic stress and genes for mechano-sensing proteins tend to correlate well with the systolic stress itself. We conclude that different groupings of genes having different temporal expression patterns correlate well with different measures of the wall mechanics, hence emphasizing a need for age-dependent, gene-specific computational modeling of postnatal development.

Adsorption Effects of Isoniazid Drug Over Carbon Nanotube (C56H16) and Ab‐Initio Molecular Dynamics Simulation (ADMP) – A Computational Quantum Chemical Approach

AbstractTuberculosis (TB) is a deadly disease of global concern. The previous work studies the geometric optimization, vibrational analysis, TDDFT, and electronic properties of the TB pathogen drug isoniazid (ISO). This communication will discuss the changes in geometry, electronic properties, and shielding parameters of ISO‐absorbed carbon nanotube (CNT) (CNT‐ISO, C56H16). This study has used the DFT/B3LYP/6–311G (d, p) method for the first time to report ISO's electronic structure and interaction parameters on the CNT surface. The same level theory is used to discuss the thermodynamic stability of CNT‐ISO. The calculated UV spectra of CNT are compared with UV spectra of CNT‐ISO by using the same level theory in a water solvent, which provides a better comprehension of CNT as a drug delivery system after absorption of the ISO in the human body. The nature and strength of interactions have been discussed with the help of NBO and AIM analysis, and the frontier orbital highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) gap, chemical softness, and chemical hardness have been calculated to understand its complete chemical properties. The characters of the frontier molecular orbitals are discussed and analyzed by comparing the DOS spectra of CNT with CNT‐ISO. It has also examined the scan plot of interaction with time using ab‐initio dynamics simulation (ADMP) calculations.

Low-profile dielectric grooved GRIN lens for broadband millimeter-wave applications

Microwave lenses are utilized at millimeter waves to ensure high-gain and narrow-beamwidth radiation patterns. This paper proposes full-dielectric grooved graded-index (GRIN) lenses with an improved effective permittivity profile of the lens. The proposed grooved GRIN lenses combine changes in the lens geometry with the stepped effective permittivity profile to better approximate the theoretical permittivity profile of the lens. A prototype GRIN lens has been designed, fabricated, and measured. The designed lens has diameter and thickness equal to 72 mm and 19.04 mm (5.3λ0, 1.4λ0 at the center frequency of 22 GHz), respectively. The lens covers the entire K-band (18–26.5 GHz) with aperture efficiency better than 44%. Moreover, it achieves the maximum gain and aperture efficiency of 23 dBi and 64%, respectively.

Transient mixed thermal elastohydrodynamic lubrication analysis of aero ball bearing under non-steady state conditions

A transient mixed thermal elastohydrodynamic lubrication model of bearing considering the thermal effect and the changes in velocity, load, and contact geometry is proposed. Based on the bearing dynamic and lubrication analysis, the effects of bearing rotational speed and start-stop conditions on the dynamic behavior and lubrication performance are studied. Results show that when the bearing rotational speed exceeds a certain critical value, the increasing speed will reduce the film thickness, especially the outer raceway. The increasing bearing acceleration can cause a higher slide-roll ratio and film temperature at the initial start-up process. Compared with the start-up process, the lubrication change in the shut-down process has a similar opposite trend, but the overall lubrication performance is better.