Changes In Geometry Research Articles

Vibronic Splitting of the Electronic Origin in Two Conformers of the 3-Tolunitrile Dimer.

3-tolunitrile (3-TN) can form three different dimers, which differ in the relative orientation of the methyl groups. We determined the geometry changes of two of these conformers of 3-TN upon electronic excitation via a Franck-Condon fit of the vibronic intensities in the fluorescence emission spectra. Both aromatic rings expand upon electronic excitation, showing a delocalized one-photon excitation of the cluster. The conformer with the smaller center-of-mass distance shows an unusual order of the split components of the electronic origin. We attribute this changed order to the stronger charge transfer contributions to the splitting and a partial breakdown of the point dipole approximation, made in the Frenkel type interaction.

Heat transfer augmentation by using different techniques in small scale channels: A review study

In this paper highlights the most significant recent developments in scientific study on Heat sinks are thermal management components made of materials with sufficient thermal conductivity qualities. Due to the increase in operating power and speed as well as the general reduction in system size, the issues of heat removal and temperature management have taken on increasing importance in these studies. Changing the geometry of extended surfaces, the material from which they were made, the working fluid that ran over them and or the dimension of the channel, are some of the subcategories in which studies have been conducted. The current review addresses the main recent findings in the forced convection heat transfer happened at laminar flow inside small scale diameters channels. The recent studies indicated a remarkable enhancement with the change of Re, D and internal geometry of channel. The configuration of flow passages also adopted as a different passive technique to enhance thermal fluid flow.

How Flexible Is the Hydrogen Sulfide Molecule Structure? Influence of Hydrogen Sulfide Molecule Geometry on Its Hydrogen Bonds.

The geometry of hydrogen sulfide was studied by calculating potential energy surface (PES) with over 1800 configurations. The calculations were performed at very accurate CCSD(T)/aug‐cc‐pvz5 level. The most stable geometry on PES has bond angle (H‐S‐H) of 92.40⁰ and bond length (S‐H) of 1.338 Å. PES shows that hydrogen sulfide is a quite flexible molecule. Namely, it can change the bonding angle (H‐S‐H) in the range of . 15.6⁰ (from 84.6⁰ to 100.2⁰) and the bond lengths (S‐H) in the range of 0.082 Å (from 1.299 Å to 1.381 Å) with an energy increase of only 1.0 kcal/mol. An influence of hydrogen sulfide geometry on its hydrogen bonds was studied on several hydrogen sulfide/hydrogen sulfide and water/hydrogen sulfide dimers. It showed that the change of hydrogen sulfide geometry does not influence the strength of hydrogen bond. Fully optimized geometries in gas and water solution phases revealed structural differences of both monomers and dimers in gas phase and water phase. SAPT analysis of the optimized dimer geometries showed that in all the dimers electrostatic is the most dominant contribution, while, in the dimers with hydrogen sulfide, the influence of dispersion contribution becomes quite pronounced.

Neural-Network and Multivariate-Normal-Distribution Hybrid Method for Real-Time Ground-Shaking Reconstruction

ABSTRACT Ground-shaking maps provide a spatial representation of the impact of a seismic event in terms of ground-motion parameters (GMPs), especially useful in the context of seismic monitoring and civil protection operations. Algorithms used to compute these maps usually rely on seismic source parameters to steer the interpolation process and consequently are limited to operate in near-real time. The present work introduces a novel algorithm that combines neural networks with the multivariate normal distribution method to reconstruct ground-shaking maps using only data available in real time, improving on previously proposed algorithms. The core idea of the proposed algorithm is to maintain the structure proposed by ShakeMap while removing the dependence on the source parameters, imposed by the use of ground-motion prediction equations, by replacing them with an appropriate neural network working on the GMPs recorded in real time at the seismic stations. The overall workflow of the method and the details of the neural network architecture and training are described. A model trained on synthetic and recorded data to target seismic events affecting the Italian territory is tested using the 2016 Norcia, Italy, earthquake showing the method reconstruction capabilities, its robustness to noise and to network geometry changes, and its real-time potential.

Fermented Rapeseed Meal as a Dietary Intervention to Improve Mineral Utilization and Bone Health in Weaned Piglets.

This study examined the effects of incorporating fermented rapeseed meal (FRSM) into the diet of newly weaned piglets on mineral digestibility and bone health. Experimental diets containing varying levels of FRSM (8%, 12%, 15%, and 25%) were introduced to the piglets at 18 days of age, prior to weaning at 28 days. These diets were continued until the piglets were euthanized at 42 days of age. Mineral absorption was assessed using the apparent total tract digestibility (ATTD) method and blood plasma element analysis, while bone mineral content and mechanical properties were evaluated through densitometry and three-point bending tests. The results showed that intermediate levels of FRSM (12-15%) significantly enhanced the digestibility of key minerals, including phosphorus, calcium, magnesium, copper, zinc, and iron. This improvement was linked to increased femoral mineral content and bone stiffness, as well as a higher yield point, likely due to enhanced collagen synthesis. Additionally, there was an increase in bone fracture load and fracture stress, potentially due to changes in the organization of the bone mineral phase, as no changes in bone mid-shaft mineral density or geometry were observed. These findings suggest FRSM as a promising dietary component for improving mineral bioavailability and bone health in piglets.

Longitudinal Analysis of Bone Metabolic Markers and Bone Mechanical Properties in STZ-Induced Diabetic Rats.

Background: This longitudinal study examined the early effects of type 1 diabetes on bone mechanical properties and metabolic markers in mature rats, focusing on the natural progression of diabetes-induced changes without external treatments. Methods: Forty-eight 8-month-old male Wistar rats were divided into two groups, with one group receiving a single dose of streptozotocin (STZ, 60 mg/kg). Assessments were performed 2, 4, and 8 weeks post-administration, including serum biochemical analyses, bone marker assessments, and mechanical bone tests. The data were analyzed using two-way ANOVA to evaluate the impact of time and treatment. Results: At 2 weeks, diabetic rats showed increased fasting blood glucose (p < 0.001), decreased insulin levels (p = 0.03), and changes in HOMA markers (p < 0.001), liver enzymes (p < 0.001), inflammatory markers (p < 0.001), and bone metabolism markers (osteocalcin (p < 0.001), OPG (p = 0.006), RANKL (p < 0.001), and OPG/RANKL ratio (p < 0.001)), with initial alterations in bone geometry. By week 4, decreased body weight in the diabetic group (p < 0.001) led to further changes in bone geometry and initial differences in mechanical properties. At 8 weeks, significant declines in body (p < 0.001) and bone (p < 0.001) weights were observed, along with further deterioration in bone geometry and mechanical properties. Conclusions: The study highlights the significant impact of STZ-induced diabetes on bone health as early as two weeks post-STZ administration, with marked temporal changes in biochemical markers and mechanical properties.

Ambulatory blood pressure is associated with left ventricular geometry after 10 years in hypertensive patients with continuous antihypertensive treatment.

Both aging and high blood pressure (BP) are associated with a risk of left ventricular concentricity and hypertrophy. We hypothesized that optimal BP management improves left ventricular remodeling beyond aging. Among 558 hypertensive patients on continuous antihypertensive treatment and without concurrent heart disease who were referred to a cardiology clinic with echocardiography and ambulatory BP monitoring data, 142 patients' echocardiographic data was available after 10 years. Baseline BP and changes in left ventricular geometry were evaluated. Mean age at baseline was 71.0 years old. Baseline daytime BP was 129.9/72.4 ± 17.1/10.2 mmHg and nighttime BP was 122.5/67.1 ± 16.9/9.1 mmHg. After 10 years, left ventricular mass index (LVMI) and relative wall thickness (RWT) significantly decreased from 104.5 ± 26.3 to 97.9 ± 26.4 g/m2, p = 0.003 and 0.51 ± 0.09 to 0.47 ± 0.09, p < 0.001, consecutively. Among patients with hypertrophic geometry at baseline, 17.2% reverted to normal geometry at follow-up. Daytime systolic BP (136.9 ± 18.5 mmHg vs 126.2 ± 16.5 mmHg, p = 0.03), nighttime systolic BP (126.2 ± 17.7 mmHg vs 116.3 ± 16.0 mmHg, p = 0.038) and daytime pulse pressure (63.5 ± 17.3 mmHg vs 53.1 ± 14.9 mmHg, p = 0.022) at baseline were higher in patients who remained hypertrophic than those without hypertrophy at follow-up. On logistic regression analysis, daytime, nighttime systolic BP, and daytime pulse pressure were significantly related to the regression of hypertrophy adjusted for age, sex, eGFR, BMI, LVMI, and RWT at baseline. For conclusion, antihypertensive treatment for 10 years improved LV geometry despite aging. Ambulatory BP and pulse pressure at baseline predicted the change of LV geometry after 10 years.

Creatine supplementation: facts and myths

Introduction: Creatine (N-methylguanidinoacetic acid) is a peptide built of three amino acids: glycine, arginine and methionine. Its function is to store energy. It is common practice to intake creatine as a dietary supplement. Because of that, we decided to try to answer the question if there are scientifically documented advantages of creatine supplementation. Review method: We analyzed the newest research conducted from 2017 to 2024. The studies were searched in online databases like PubMed and Google Scholar. We focused on the impact of creatine supplementation on the ageing population, professional athletes, the course of some diseases, cognitive functions and body composition Results: Creatine supplementation is beneficial in professional sports. There are some signals that creatine may worsen lung conditions in sportsmen. In the ageing population, creatine supplementation boosts the results of resistance training on ageing muscle performance. There are suggestions that in this population bone geometry changes due to a combination of training and creatine supplementation may be protective against hip fracture. Creatine can also enhance cognitive functions as well as lead to positive changes in body composition. Supplementation of creatine seems to reduce symptoms of long COVID-19. It may be also beneficial among children with dermatomyositis and patients with ischemic heart disease. Conclusions: Creatine supplementation may be beneficial in some populations. It can also enhance cognitive functions as well as lead to changes in body composition. Some effects of creatine supplementation are still controversial and further investigation is needed to determine its usefulness. Keywords: creatine, body composition, long COVID-19, ageing population, professional sport, cognitive functions, dermatomyositis, ischemic heart disease

Theoretical and experimental study of elastocaloric responses in liquid crystalline elastomers

We carry out systematic experimental and theoretical study of elastocaloric (eC) response in nematic liquid crystal elastomers (LCEs), which possess the elastic properties of elastomers combined with the orientational order of liquid crystals. The chemical linking of mesogens to the polymer backbone enables thermomechanical response yielding a large spontaneous change in the LCE geometry on varying the temperature. In LCEs, a relatively large eC effect could be obtained upon adiabatic application or removal of a stress field in the isotropic state near phase transformation to the more ordered state. In these cases a change in the isothermal entropy or adiabatic temperature is compensated with the temperature change of liquid crystal elastomers. This effect could be exploited towards soft condensed state cooling technologies that gain increasing interest due to environmental issues, low-cost and low stimuli field. In the present study we measure directly the elastocaloric temperature change. Experimental measurements are interpreted using a modified Landau-de Gennes mesoscopic model taking into account both internal and external stress fields. Our systematic study identifies conditions yielding responsivity of a few K/MPa, which is two orders of magnitude larger than in the shape memory alloys, the most intensively studied materials for this effect.

Cardiovascular Adaptation in Fetal Growth Restriction: A Longitudinal Study From Fetuses at Term to the First Year of Life.

To investigate longitudinal trends in fetal and offspring cardiovascular adaptation in fetal growth restriction (FGR). Prospective longitudinal study. Fetal Medicine Unit. Thirty-five FGR pregnancies and 37 healthy controls assessed as term fetuses (mean age 37 ± 1 weeks) and again in infancy (mean age 8 ± 2 months). Conventional echocardiographic techniques, tissue Doppler imaging and speckle tracking echocardiography. Left ventricular (LV) and right ventricular (RV) geometry and function. Echocardiographic parameters were normalised by ventricular size adjusting for differences in body weight between groups. Compared to healthy controls, late FGR fetuses showed significant alterations in cardiac geometry with more globular LV chamber (LV sphericity index, 0.56 vs. 0.52), increase in biventricular global longitudinal systolic contractility (MAPSE, 0.29 vs. 0.25 mm; TAPSE, 0.42 vs. 0.37 mm) and elevated cardiac output (combined CO: 592 vs. 497 mL/min/kg, p < 0.01 for all). Indices of LV diastolic function in FGR fetuses were significantly impaired with myocardial diastolic velocities (LV A', 0.30 vs. 0.26 cm/s; IVS E', 0.19 vs. 0.16 cm/s) and LV torsion (1.2 vs. 3.5 deg./cm, p < 0.01 for all). At postnatal assessment, FGR offspring revealed persistently increased SAPSE (0.27 vs. 0.24 mm), LV longitudinal strain (-19.0 vs. -16.0%), reduced LV torsion (1.6 vs. 2.1 deg./cm) and elevated CO (791 vs. 574 mL/min/kg, p < 0.01 for all). Perinatal cardiac remodelling and myocardial dysfunction in late FGR fetuses is most likely due to chronic placental hypoxaemia. Persistent changes in cardiac geometry and function in FGR offspring may reflect fetal cardiovascular maladaptation that could predispose to long-term cardiovascular complications in later life.

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

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. However, the impact of LVH and LAE and their regression following antihypertensive therapy on atrial fibrillation incidence remains unclear. This retrospective analysis included consecutive patients with sinus rhythm who underwent echocardiography at hypertension diagnosis and after 6-18 months between 2006 and 2021 at tertiary care centres in Korea. LVH was defined as LV mass index greater than 115 g/m2 (men) and greater than 95 g/m2 (women), and LAE was defined as LA volume index greater than 42 ml/m2. The occurrence of new-onset atrial fibrillation (NOAF) was assessed in relation to changes in LVH and LAE status. Among the 1464 patients included, 163 (11.1%) developed NOAF during a median 63.8 [interquartile range (IQR) 35.9-128.5] months of surveillance period. New-onset LVH [adjusted hazard ratio (aHR) 1.88, 95% confidence interval (CI) 1.20-2.94, P = 0.006] and LAE (aHR 1.89, 95% CI 1.05-3.40, P = 0.034) were significant predictors of NOAF. Conversely, regression of LVH (aHR 0.51, 95% CI 0.28-0.91, P = 0.022) or LAE (aHR 0.30, 95% CI 0.15-0.63, P = 0.001) was associated with a reduced risk for developing NOAF. Patients with both LVH and LAE at follow-up echocardiography had a higher risk for NOAF (aHR 4.30, 95% CI 2.81-6.56, P < 0.001) than those with either LVH or LAE or those with neither. The changes in left heart geometry can serve as a predictive marker for NOAF in patients with hypertension.

Internal Conversion Cascade in a Carbon Nanobelt: A Multiconfigurational Quantum Dynamical Study.

Carbon nanobelts feature intriguing photophysical properties, due to their high symmetry and structural rigidity. Here, we consider a (6,6) armchair carbon nanobelt, i.e., the very first carbon nanobelt to be synthesized [Povie et al., Science 2017, 356, 172] and characterize the internal conversion dynamics using multiconfigurational quantum dynamics via the multi-layer multiconfiguration time-dependent Hartree (ML-MCTDH) method. A symmetry-adapted linear vibronic coupling Hamiltonian for 26 electronic states and 210 vibrational modes is employed. Electronic excitations are found to decay through a dense manifold of excited states, which interact via multiple conical intersections, while inducing minimal geometry change. It is shown that a rapid coherent decay, exhibiting a nonvanishing quantum flux on a time scale of less than 50 fs, transitions toward a slower, decoherent decay at longer times. As previously suggested in the literature, electronic relaxation is hindered by phonon bottlenecks such that a stepwise internal conversion cascade is observed. The computed vibronic absorption spectrum is shown to be in good agreement with the experimental spectrum.

A Well-Defined Magnesium Complex of C70 6.

Controlling and understanding charge state and metal coordination in carbon nanomaterials is crucial to harnessing their unique properties. Here we describe the synthesis of the well-defined fulleride complex [{(Mesnacnac)Mg}6C70], 2, (Mesnacnac)=HC(MeCNMes)2, Mes=2,4,6-Me3C6H2, from the reaction of the β-diketiminate magnesium(I) complex [{(Mesnacnac)Mg}2] with C70 in aromatic solvents. The molecular structure of complex 2 was determined, providing the first high-quality structural study of a complex with the C70 6- ion. In combination with solution state NMR spectroscopic and DFT computational studies, the changes in geometry and charge distribution in the various atom and bond types of the fulleride unit were investigated. Additionally, the influence of the (Mesnacnac)Mg+ cations on the global and local fulleride coordination environment was examined.

Redesigning heat exchanger channels: A local entropy generation approach

This paper proposes a redesign technique for heat exchanger channels based on a Local Entropy Generation (LEG) analysis and numerical simulations. The approach first divides the computational domain into zones and then identifies the zones responsible for increasing irreversibilities due to viscous and heat transfer effects. By evaluating different geometric features and flow conditions, the wall shape is modified (zone by zone) with the configurations that offer the lowest local entropy generation rates. The redesigned channels demonstrate that sudden changes in geometry along the streamwise direction reduce the size of regions with high thermal entropy generation and promote the creation of vortices, thereby reducing the magnitude of thermal irreversibilities. Smooth wall shape transitions might not be desirable when the goal is to improve heat transfer. The redesign process enhances the thermal performance of the system without significantly increasing power demand. The proposed methodology is evaluated using three wavy channels with a non-uniform amplitude-to-wavelength ratio (β1,β2,andβ3) since they allow for better management of wall geometry. As demonstrated for case β1, the LEG analysis enables the construction of new channels with a thermal performance 3.9 % superior to those with a uniform amplitude-to-wavelength ratio of α = 0.16 (best-case scenario), but with approximately 20 % less pumping power. While this study employs wavy channels as a case study, the methodology is broadly applicable to various heat exchanger configurations, including trapezoidal, triangular, and zigzag channels, making it a versatile tool for improving thermodynamic performance across different designs.

Увеличение продолжительности работы установки электроцентробежного насоса для повышения безопасности и сокращения рисков при спускоподъемных операциях

The study analyzes basic complications associated with generating mechanical impurities; numeric modeling to optimize the electrical submersible pump operation has been performed. Modeling the fluid flow in combination with erosion models has been used to determine the key factors facilitating the erosion of the electrical submersible pump action wheel impeller during oil production. In order to obtain a complete view of the flow and erosion properties, modeling has been performed for the entire fluid flow route. Modeling of the flow and the action wheel component erosion has been performed to determine the impact of the flow imbalance as well as to ensure the boundary conditions at the input for the modeling. The modeling results have shown: the rotational flow introduced in the mixing point at the action wheel input significantly impacts the strength properties of the modeled object; the area most exposed to erosion is the area of the action wheel impeller. The values of loss of material have been determined via the time sequence of geometry changes in the compounds in combination with the actual hydraulic operational parameters. The flow trajectories proposed for modeling show that the recirculating flow is the dominant. It is widely adopted that recirculation is one of the main causes of increased erosion in the compounds of the electrical submersible pump as it leads to the high frequency of high-speed impacts by sand particles. In order to reduce the erosion risk, the analysis aiming to identify the impeller geometrical parameters has revealed that the erosion rate in the compound can be reduced by decreasing the inclination of the action wheel impeller. The study has demonstrated that numerical modeling can provide a detailed and precise evaluation of erosion potential in cases associated with the high velocity of fluid flow with particles of mechanical impurities.

On-demand mitral valve morphometrics during surgical repair

Abstract Mitral valve regurgitation is one of the most common heart valve diseases that can occur when the structural composition of the mitral valve is affected. Mitral valve repair, typically performed in a minimally invasive setting, is a complex surgery that aims to reinstate the structural integrity of the valve and thereby restore normal valve function. The current practice lacks quantification of geometrical changes and interactive 3D visualization that could enhance the understanding of pathomorphological changes and impact of surgical correction. This work presents functionalities from smartMVR, a quantitative tool to measure, compare, and analyse changes in mitral valve geometry from data captured on-demand using an RGB-D camera. The feasibility of the approach is demonstrated on a silicone replica of a pathological mitral valve that is iteratively corrected using common surgical techniques.

Morphometric analysis of growth-related changes in femoral geometry

Morphometric analysis of growth-related changes in femoral geometry

Hamstring Muscle-Tendon Geometric Adaptations to Resistance Training Using the Hip Extension and Nordic Hamstring Exercises.

Targeted resistance training stimulates hamstring muscle hypertrophy, but its effect on tendon-aponeurosis geometry is unknown. This study examined changes in hamstring muscle, free tendon, and aponeurosis geometry following a 10 week Nordic or hip extension exercise intervention. Thirty recreationally active males were randomly allocated (n = 10 per group) to a Nordic, hip extension, or control group. Magnetic resonance imaging of both thighs was acquired pre- and post-intervention. Changes in free tendon and aponeurosis volume for each hamstring muscle, biceps femoris long head (BFlh) aponeurosis interface area and muscle volume-to-interface area ratio were compared between groups. Regional changes in muscle CSA were examined via statistical parametric mapping. The change in semimembranosus free tendon volume was greater for the Nordic than control group (mean difference = 0.06 cm3, 95% CI = 0.02-0.11 cm3). No significant between-group differences existed for other hamstring free tendons or aponeuroses. There were no between-group differences in change in BFlh interface area. Change in BFlh muscle volume-to-interface area ratio was greater in the hip extension than Nordic (mean difference = 0.10, 95% CI = 0.007-0.19, p = 0.03) and control (mean difference = 0.12, 95% CI = 0.03-0.22, p = 0.009) groups. Change in muscle CSA following training was greatest in the mid-portion of semitendinosus for both intervention groups, and the mid-portion of BFlh for the hip extension group. There was limited evidence for tendon-aponeurosis hypertrophy after 10 weeks of training with the Nordic or hip extension exercises. For the BFlh, neither intervention altered the interface area although hip extension training stimulated an increase in the muscle volume-to-interface area ratio, which may have implications for localized tissue strains. Alternative muscle-tendon loading strategies appear necessary to stimulate hamstring tendon adaptations.

Traffic analysis of different geometries of a junction for optimization of vehicle capacity and traffic safety increase

Abstract Identifying various vehicle movement characteristics inside a network requires a careful assessment and different measurements technics, in regards to road traffic studies. These measures are influenced by a variety of variables, including the direction of traffic, changes in daily transportation demand, junction geometry and location in areal of study, style of road and also the size of the study area. Examining various geometries and arrangements of lanes with different distributions of vehicle platoons of the junction based on traffic-related elements is the goal of this essay. The analysis of the junction in regards to the speed, volume, capacity, pollution and traffic safety can give alternative solution and provide a foundation for the implementation of various political strategies in the area.

Numerical Study of Cavitation Phenomenon in a Venturi Tube

This research aims to understand and numerically analyze the cavitation phenomenon that occurs in Venturi tubes with variations in throat length and pressure changes. This research uses Ansys Fluent 2023 R2 numerical simulation with venturi tube geometries of 25 mm, 30 mm, and 35 mm and pressures of 300,000, 600,000, and 900,000 Pa. A multiphase flow model with water liquid and water vapor is applied to predict cavitation using a mixture model. RANS steady state conditions with the k-ε turbulence model are used to solve the continuity, momentum, energy and volume fraction equations. The Schnerr-Sauer cavitation model calculates the phase transition between water-liquid and water vapor. Geometry varies by reference journal with different converging and diverging angles, outlined in tables and figures. 2D simulations are carried out using a pressure based solver with specified boundary conditions, using the Presto! for pressure solutions, and upwind and Quick schemes for discretization. The results of this research show that 1) Length throat 25 mm has the most stable distribution compared to 30 and 35 mm geometries at a pressure of 600,000 Pa. 2) The cavitation phenomenon is influenced by changes in geometry where at 35 mm geometry greater cavitation occurs in the area near the wall inlet convergent. 3) At a pressure of 900,000 Pa, the cavitation area that forms becomes larger and becomes a critical point in this journal.