Excess Energy Research Articles

Multi-Criteria Optimization of the Paper Production Process Using Numerical Taxonomy Methods: A Necessary Condition for Predicting Heat and Electricity Output in a Combined Heat and Power (CHP) System

The subject of this study is the optimization of the paper production process in one of Poland’s leading paper mills. In addition to its primary objective of paper production, the company generates heat and electricity for internal consumption and external clients, including the local municipality. Surplus energy may be sold on the power exchange; however, this requires forecasting the quantity of energy to be sold 24 h in advance, which introduces an element of uncertainty. Production stoppages, often caused by random events such as paper breakage, force a power decrease in the CHP system, further complicating energy forecasting. To minimize the occurrence of such events, numerical taxonomy methods were employed to determine the optimal screen speed (Vs) and winding speed (Vn) for two paper machines, based on the type and weight of the paper produced. This analysis utilized detailed daily data collected by the company over the period 2015–2020. The findings contribute to minimizing the occurrence of paper roll tearing, thereby reducing the risk of inaccurate forecasts of the energy and heat produced by the CHP system. Furthermore, the methodology employed in this study may be effectively applied to other optimization problems in industrial processes.

Interatomic Coulombic electron capture beyond the virtual photon approximation.

Via the interatomic Coulombic electron capture (ICEC) process, an electron can be captured by an atom or a molecule, while the binding and excess energy is transferred, via a long-range Coulomb interaction, to a neighboring atom or molecule. The transferred energy can be used to ionize or electronically excite the neighboring species. When the two species are asymptotically far apart, an analytical formula for the ICEC cross sections can be derived. The latter can then be estimated using only the energies and the photoionization cross sections of each species. In this work, we develop an analytical model that allows us to predict the ICEC cross sections when the size of the involved species is comparable to the distance between the two entities. Using abinitio R-matrix results for various systems, we show that the new model reduces the error of the asymptotic formula by two orders of magnitude on average while only using parameters that can be taken from the properties of each species.

A Parametric Study on the Stability, Geometry and Hardness of AISI 308LSi WAAM-GMAW

Wire arc additive manufacturing (WAAM) has been established to be an efficient and cost-effective additive manufacturing technique for fabricating functional metallic parts from scratch. However, there is need to determine optimal processing condition for each material system to produce high-quality parts. In this work, a parametric study of WAAM of AISI 308LSi was performed to determine the processing condition(s) at which single tracks of high dimensional accuracy, excellent geometry, no visible crack and pore, and high hardness required for high-quality multi-track deposition can be achieved. The track geometries were investigated using a combination of optical microscopy and image processing software. The microstructure and hardness of the deposited single tracks were examined using optical microscopy and Vickers hardness tester respectively. A process map predicting the process stability of WAAM of AISI 308LSi was developed within a process window. Continuous single tracks of high dimensional accuracy were produced from a stable deposition process. The process becomes unstable whenever the wire deposition volume per unit length of track is in excess of the available heat energy per unit length of track. The wire feed rate and traverse speed significantly influence the stability and geometry of the single tracks. The processing conditions at which single tracks of low wetting angle (<90◦), high aspect ratio (>1.5), high surface quality, and high hardness (close to the as-received material) can be deposited were determined. These processing conditions were considered suitable for the fabrication, surface modification and repair of functional engineering parts made of 308LSi stainless steel.

Absence of the third linker domain of ApcE subunit in phycobilisome from Synechocystis 6803 reduces rods-to-core excitation energy transfer.

Phycobilisome (PBS) is a pigment-protein complex utilized by red algae and cyanobacteria in photosynthesis for light harvesting. A cyanobacterium Synechocystis sp. PCC 6803 contains PBS with a tricylindrical core built of allophycocyanin (APC) disks where six phycocyanin (PC) rods are attached. The top core cylinder is seemingly involved in attaching four PC rods and binding orange carotenoid protein (OCP) to quench excess of excitation energy. In this study, we have deleted the third linker domain (LD3) of ApcE subunit of PBS which assembles four APC discs into the top core cylinder. The mutation resulted in PBS with bicylindrical core, structurally comparable to the naturally existing PBS from Synechococcus 7942. Lack of LD3 and the top APC cylinder reduces the excitation energy transfer between PC and APC in the mutant. Moreover, these PBSs are more prone to light induced-photodamage and do not bind to the photoactivated orange carotenoid protein (OCP), a known PBS excitation quencher. These findings highlight the complex and elegant interplay between PBS architecture and functional efficiency, suggesting that in PBSs with naturally tri-cylindrical cores, the top cylinder has essential roles in recruiting the rods and proper binding of OCP and recruitment of the four PC rods.

“Dead Lithium” Formation and Mitigation Strategies in Anode‐Free Li‐Metal Batteries

AbstractThin lithium‐metal foil is a promising anode material for next‐generation batteries due to its high theoretical specific capacity and low negative potential. However, safety issues linked to dendrite growth, low‐capacity retention, and short cycle life pose significant challenges. Also, it has excess energy that must be minimized in order to reduce the battery costs. To limit excess lithium, practical lithium metal batteries need a negative‐to‐positive electrode ratio as close to 1 : 1 as possible, which can be achieved through limiting excess lithium or using an “anode‐free” metal battery design. However, both designs experience fast capacity fade due to the irreversible loss of active lithium in the cell, caused by the formation of the solid electrolyte interphase (SEI), dendrite formation and “dead lithium,” – refers to lithium that has lost its electronic connection to the anode electrode or current collector. The presence of dead lithium in batteries negatively affects their capacity and lifespan, while also raising internal resistance and generating heat. Additionally, dead lithium encourages the growth of lithium dendrites, which poses significant safety hazards. Within this fundamental review, we thoroughly address the phenomenon of dead lithium formation, assessing its origins, implications on battery performance, and possible strategies for mitigation. The transition towards environmentally friendly and high‐performance metal batteries could be accelerated by effectively tackling the challenge posed by dead lithium.

Optimal planning and operation of heterogeneous autonomous and grid-connected microgrids based on multi-criteria techno-economic, environmental, and social indices

Sustainable energy transition involves the execution of recent technologies as a means of ensuring energy access and security. However, the increasing adoption of such technologies, particularly in the presence of diverse constraints, poses significant challenges from a planning perspective. In this context, the multi-objective analysis offers valuable insights for decision-making that balances mutual benefits, as relying solely on a single objective may increase the risk level for stakeholders engaged in coordinated decisions. Based on the real dataset, this study presents a comparative multi-criteria techno-economic, environmental, and social evaluation of site-specific unified standalone and grid-connected hybrid microgrids. The study employs a modified Last Cluster Mean Carried Forward approach for data processing, incorporating the Proprietary Derivative-free Algorithm and Original Grid-Search Algorithm to ensure a standardized comparison. Results reveal the substantial advantages of grid-connected systems over standalone counterparts, with reductions of 12.54 % to 63.73 % and 68.93 % to 89.13 % in terms of Net Present Cost and Levelized Cost of Energy, respectively. Grid-connected systems exhibit superior adaptability, recovering 52.3 % to 98.1 % surplus energy with a Renewable Fraction averaging 77.1 % to 87.9 %. However, these systems were hindered by frequent interruptions and required a minimum capacity shortage of 2.5 % to 3.5 %. Furthermore, grid-connected systems have proved feasible when carbon emissions, forests required to absorb the emissions, and the Social Cost of Carbon Emissions are considered in the range of 4.65–67.13 kiloton (metric), 423.32–6108.53 ha, and $0.24-$3.42 million, respectively. Social analysis and sensitivity analyses are performed to justify the robustness and adaptability. Lastly, the findings are followed by policy recommendations and results validation by comparing prevailing government tariffs and other studies.

Личностные особенности и самоотношение лиц с психогенным перееданием

<p><strong>Background. </strong>According to the World Health Organization, in 2023, excess weight was observed in 2,5 billion adults aged 18 and older. Individuals with obesity suffer from chronic somatic diseases, face social isolation. Understanding the psychological and social factors behind weight gain allows us to develop effective programs to prevent obesity and help people lose weight. <strong>Objective.</strong> The aim of this study is to analyze the analysis of personality traits and self-attitudes in individuals with excess body mass. <strong>Hypothesis.</strong> Individuals with psychogenic overeating have an increased level of neuroticism, perfectionism and internal conflict, as well as reduced self-acceptance. <strong>Materials and methods. </strong>101 people with eating disorders were examined. All respondents were divided into three groups according to the criterion of body mass index (BMI): 1 group - 33 people with pre-obesity and obesity of the first degree, average age 40±13 years; 2 group - 20 people with second degree obesity, average age 35±12 years; group 3 - 48 people with third degree obesity, average age 44±10 years. The socio-demographic characteristics of the respondents and medical documentation data were studied. Psychological testing was conducted using: the KON-2006 Neurotic Personality Questionnaire to assess neurotic personality traits, the Multidimensional Perfectionism Scale (MPS), a questionnaire to study self-esteem. <strong>Results. </strong>Analysis of the study results showed a high level of neuroticism for individuals with different BMIs in all groups, the violation of self-attitude is primarily associated with the perception of one's appearance, perfectionism is not a personal feature associated with psychogenic overeating. Low self-esteem of external data is combined in them with narcissism and a positive assessment of their personal characteristics. <strong>Conclusions. </strong>The results obtained can be used to develop and improve the effectiveness of psychological weight correction programs for psychogenic overeating, based on taking into account the personal factors of obesity.</p>

Generalized Rosenfeld–Tarazona scaling and high-density specific heat of simple liquids

The original Rosenfeld–Tarazona (RT) scaling of the excess energy in simple dense fluids predicts a ∝T3/5 thermal correction to the fluid Madelung energy. This implies that the excess isochoric heat capacity scales as Cvex∝T−2/5. Careful examination performed in this paper demonstrates that the exponent −2/5 is not always optimal. For instance, in the Lennard-Jones fluid in some vicinity of the triple point, the exponent −1/3 turns out to be more appropriate. The analysis of the specific heat data in neon, argon, krypton, xenon, and liquid mercury reveals that no single value of the exponent exists, describing all the data simultaneously. Therefore, we propose a generalized RT scaling in the form Cvex∝T−α, where α is a density- and material-dependent adjustable parameter. The question concerning which material properties and parameters affect the exponent α and whether it can be predicted from general physical arguments requires further investigation.

Techno-economic assessment of an industrial prosumer with biomass investment and time varying tariffs: An Australian case study

This paper investigates the potential for a value chain framework to deliver impact through innovation across the timber manufacturing process. A new and efficient combustion technology that converts timber waste to energy is considered for this study. The framework to estimate the new energy costs and savings derived from the new technology, compared with current supply and demand scenarios, as well as the value generated by waste streams. The opportunity of selling excess energy to the grid or local area has been investigated. Two alternatives of time-varying tariffs and time-varying tariffs with biomass, are used for assessing the costs. According to the numerical results, tariff 3, with 25,000 tonnes of biomass feedstock per year, is the best option for the mill. The price efficiency index is reduced by approximately 40% compared to this option’s usual business. In addition, the investor can save the whole energy bill compared to the current business as usual. The investor could make a profit of $460,401 per year by selling energy to the grid. The annual saving is around six times higher than the savings gained using a time-varying tariff alone. However, this option requires $1,811,635 as annual life cycle cost, with a payback period of ten years. The lowest levelised cost of energy of 0.14 c/kWh is also obtained for this option.

Longitudinal Fluvial Dispersion of Coarse Particles: Insights From Field Observations and Model Simulations

AbstractIn this study, we use field observations augmented with model simulations to examine gravel dispersion over nine years (2007–2015) in Halfmoon Creek. The observations of flow, entrainment, and dispersion were used to develop a forward model utilizing the Einstein‐Hubbell‐Sayre (EHS) compound Poisson process. The observed mean virtual velocity of the tracer population slows down with cumulative excess energy after the 2010 large event. The forward model deviates from the observations in representation of tails, overpredicts mean displacements, and shows a narrower spatial distribution. The heavy‐tailed resting times indicate prolonged immobilization of some grains, suggesting the preferential movement of other most mobile grains. As such, 34% of most mobile grains constitute 50% of the total entrainments. The consideration of preferential movement explains the longitudinal spread but still overpredicts the displacement after the 2010 event. The model was then explored to consider additional transport‐related mechanisms causing deviations, such as reduction in virtual velocity, entrainment probability, and morphological trapping of meander bends, which helps to adequately recreate the observed dispersive behavior. The available historical flow records used for simulating dispersive behavior over multiple decades reveal an abrupt increase in displacements for exceptionally large events, suggesting the exhumation of deeply buried grains back in transport. The simulation results highlight the need for tracer studies with large sample sizes and improved recovery rates for longer time frames experiencing floods of widely varying magnitudes. Such models, inspired by Einstein's stochastic theory can be valuable for various river research applications.

The regularities of spent bleached earth treatment with the ester-aldehyde fraction

The regularities of extraction of adsorbate from spent bleaching earth (SBE) of sunflower oil by the esteraldehyde fraction (EAF) have been established. The content of the substances adsorbed by SBE was 34.1%, including 19.2% free fatty acids (FFA) and 11.1% moisture. The influence of temperature (50 and 700C), extraction duration (60 and 120 min), and the mass ratio of EAF to SBE ((2–4):1) on the extraction parameters has been determined. It was found that increasing these process parameters enhances the extraction degree of the adsorbate and FFA from the bleaching earth, reaching 41.9% and 34.4%, respectively, at a temperature of 700C, extraction duration of 120 min, and a mass excess of EAF to SBC at a ratio of 4:1. Optimal conditions for the removal of FFA from SBE were identified. It was established that strong acidic sites are present on the surface of the bleaching earth, with the acidity of fresh, spent, and EAF-treated bleaching earth being 0.79, 0.77, and 0.74 mmol H+ per gram, respectively. The basicity of fresh bleaching earth was 0.073 mmol OH– per gram, indicating the ability of bleaching earth to catalyze the esterification of FFA with ethanol. The suitability of the obtained extract for the production of FFA ethyl esters was demonstrated.

Second-order dissociation and transition of heavy quarkonia in the quark-gluon plasma

We revisit the dissociation of heavy quarkonia by thermal partons at the next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the quark-gluon plasma (QGP). Utilizing the chromoelectric dipole coupling from quantum chromodynamics (QCD) multipole expansion as an effective Hamiltonian, this has been conducted in the approach of second-order quantum mechanical perturbation theory, which allows us to systematically incorporate the bound state wave functions. Employing the quarkonium wave functions and binding energies obtained from an in-medium potential model, we then numerically evaluate the dissociation cross sections and rates for various charmonia and bottomonia, where the infrared and collinear divergences are regularized by the thermal masses of medium partons. We demonstrate that distinct from the leading order (LO, also known as gluo-dissociation) counterparts peaking at relatively low gluon energy and falling off thereafter, the NLO cross sections first grow and then nearly saturate as the incident parton energy increases, as a result of the outgoing parton carrying away the excess energy. The resulting NLO dissociation rates increase with temperature and take over from the LO counterparts toward high temperatures, similar to pertinent findings from previous studies. We also evaluate the in-medium second-order transition between different bound states, which may contribute to the total thermal decay widths of heavy quarkonia in the QGP. Published by the American Physical Society 2024

Design analysis of a sustainable techno-economic hybrid renewable energy system: Application of solar and wind in Sigulu Island, Uganda

Sustainable energy is central to achieving the global Sustainable Development Goals (SDGs), particularly in electrifying underserved communities. This study examines Sigulu Island, which lacks grid electricity and relies on costly, polluting diesel generators. On-site assessments revealed a daily load demand of 1,455.705 kWh. This study designed and analyzed a Sustainable Techno-economic Hybrid Renewable Energy System (STHRES) combining solar photovoltaics and wind turbines, with battery backup, to meet the island's energy needs. The research adopted both qualitative and quantitative methods, gathering atmospheric weather conditions specific to Sigulu Island. Solar panels and wind turbines were identified as the most viable options, with the system incorporating 677 units of 1 kW solar panels and 27 units of 1 kW wind turbines, generating 839.97 kW and 640.08 kW daily, respectively. Additionally, 527 Li-ion batteries were used to store approximately 1480.05 kW of surplus energy demand to manage fluctuations capable of sustaining the island for 8 hours during a total blackout. The initial installation costs are estimated at $90,393.04 for solar PV, $27,729.82 for wind turbines, $159,169.81 for batteries, and $92,407.00 for the inverter. The STHRES is projected to save $56,917.93 annually, covering 15.4 % of the installation costs compared to diesel operations. Moreover, this system will reduce Uganda's carbon footprint by 436,035.6 kgCO₂ annually, equivalent to a 0.01 % reduction in national emissions. The proposed system decreases the Net Present Cost (NPC) from $426,617.60 to $369,699.67 and the Cost of Energy (COE) from $32.12/kWh to $ 27.79/kWh. With a 9 % Internal Rate of Return (IRR) and a 3 % Return on Investment (ROI), STHRES has a payback period of 8.2 years, demonstrating its financial and environmental benefits for Sigulu Island.

Enhancing Solar Water Heater Performance Using Phase Change Materials and Modified Encapsulation Geometry

ABSTRACTSolar energy's abundant availability in India makes it a potential solution to meet increasing energy needs without harming environment. Solar water heating (SWH) systems are effective in converting solar radiation into heat for domestic and industrial applications. However, their inability to provide hot water during nighttime or off‐sunshine hours due to the intermittent nature of solar energy presents a challenge. Thermal energy storage, particularly using phase change materials (PCMs), has emerged as a solution. In this study, spherical ball‐type encapsulated PCM, specifically RT60, was incorporated into a solar water heater tank under variable atmospheric conditions. The PCM stores excess energy during daylight and releases it when the water temperature drops below the PCM's melting point. The results reveal a significant reduction in the temperature drop of water from 4.5°C to 1.4°C when utilizing PCM compared to conventional storage water tanks without PCM. Additionally, energy storage capacity is enhanced by 5.13% with PCM incorporation. Furthermore, modifying the encapsulation geometry to a rectangular shape enhances heat transfer and reduces temperature drop even further to 0.9°C, making it a promising approach to improving SWH system performance. This study highlights the possibility of enhancing encapsulation shape and applying PCM to enhance SWH system performance. The results highlight the possibility of increasing solar thermal systems' energy efficiency and usefulness, which will support sustainable energy sources.

Adaptive robust self‐scheduling for a wind‐based GenCo equipped with power‐to‐gas system and gas turbine to participate in electricity and natural gas markets

AbstractIntegrating renewable energy, particularly wind generation, into power systems brings significant uncertainty and intermittency, challenging generation companies (GenCos) to maintain economic operations. This paper proposes a strategy for a wind‐based GenCo equipped with a gas turbine and a power‐to‐gas (PtG) system to balance wind variability. The gas turbine offsets power shortfalls by consuming natural gas, while the PtG system absorbs excess wind energy, converting it to natural gas and injecting it into the natural gas network as a form of storage. The GenCo operates in day‐ahead electricity and natural gas markets and the real‐time electricity market, addressing uncertainties from wind output, energy prices, and natural gas access. A tri‐level adaptive robust optimization model is introduced for the GenCo’s short‐term operational scheduling. At the first level, decisions related to the GenCo's participation in the day‐ahead electricity and natural gas markets are made. The second level deals with determining the worst‐case realization of the uncertainties, constrained by the budget of uncertainty and the limited range of variations of uncertain variables. The third level sets the operational strategy on the actual day, considering power and gas balance, as well as constraints for the wind farm, gas turbine, and PtG unit. A column & constraint generation (C&CG) algorithm is used to solve the model. Numerical results demonstrate the model’s effectiveness in various case studies, showing that the GenCo can manage wind uncertainties, benefit from arbitrage opportunities in electricity and gas markets, and improve economic outcomes. This approach supports the broader integration of renewable energy into power systems.

Heat stress and bleaching in corals: a bioenergetic model

AbstractThe coral-dinoflagellate endosymbiosis is based on nutrient exchanges that impact holobiont energetics. Of particular concern is the breakdown or dysbiosis of this partnership that is seen in response to elevated temperatures, where loss of symbionts through coral bleaching can lead to starvation and mortality. Here we extend a dynamic bioenergetic model of coral symbioses to explore the mechanisms by which temperature impacts various processes in the symbiosis and to enable simulational analysis of thermal bleaching. Our model tests the effects of two distinct mechanisms for how increased temperature impacts the symbiosis: 1) accelerated metabolic rates due to thermodynamics and 2) damage to the photosynthetic machinery of the symbiont caused by heat stress. Model simulations show that the model can capture key biological responses to different levels of increased temperatures. Moderately increased temperatures increase metabolic rates and slightly decrease photosynthesis. The slightly decreased photosynthesis rates cause the host to receive less carbon and share more nitrogen with the symbiont. This results in temporarily increased symbiont growth and a higher symbiont/host ratio. In contrast, higher temperatures cause a breakdown of the symbiosis due to escalating feedback that involves further reduction in photosynthesis and insufficient energy supply for $$\hbox {CO}_2$$ CO 2 concentration by the host. This leads to the accumulation of excess light energy and the generation of reactive oxygen species, eventually triggering symbiont expulsion and coral bleaching. Importantly, bleaching does not result from accelerated metabolic rates alone; it only occurs as a result of the photodamage mechanism due to its effect on nutrient cycling. Both higher light intensities and higher levels of DIN render corals more susceptible to heat stress. Conversely, heterotrophic feeding can increase the maximal temperature that can be tolerated by the coral. Collectively these results show that a bioenergetics model can capture many observed patterns of heat stress in corals, such as higher metabolic rates and higher symbiont/host ratios at moderately increased temperatures and symbiont expulsion at strongly increased temperatures.

Temperature-dependent thermophysical characterisation of N,N-Dimethylbenzylamine binary mixtures with acetophenone derivatives (propiophenone, p-chloroacetophenone and p-methyl acetophenone)

ABSTRACT This study reports the density (ρ), speed of sound (u), and viscosity (η) of N,N-dimethyl benzyl amine (DMBA) binary mixtures with propiophenone, p-methylacetophenone, and p-chloroacetophenone in a temperature range of 303.15–313.15 K for various compositions. Excess thermodynamic properties (excess molar volume, V E ; excess isentropic compressibility, κ s E ; viscosity deviation, Δη; and excess Gibbs free energy of activation of viscous flow, ΔG *E ) were derived from the experimental data. The analysis focused on understanding intermolecular interactions, particularly the influence of the inductive effect on hydrogen bonding and dipole–dipole interactions within the mixtures. The Jouyban-Acree model was employed to predict the densities, speeds of sound, and viscosities. The model’s accuracy was assessed using the mean relative deviations (MRDs) and individual relative deviations (IRDs) between the calculated and experimental values. To further support these findings, Fourier Transform Infrared (FT-IR) spectroscopy was conducted to provide complementary insights into the intermolecular interactions within the mixtures.

Photoinhibition Sensitivity of Abies sachalinensis Saplings Under Different Leaf Mass per Area Conditions: Insights into Acclimation to Current and Future Light Environments

Photoinhibition, a common physiological obstacle in forest regeneration, results from rapid light elevations after removing upper-layer trees, thereby impeding sapling growth and survival. The leaf mass per area (LMA), which reflects the current light environment, may predict saplings’ responses to future elevations in light intensity. However, the relationship between the LMA and photoinhibition sensitivity in boreal forest evergreen conifers remains unclear. In this study, we explored whether the LMA was related to photoinhibition sensitivity in A. sachalinensis saplings. Saplings with a high LMA exhibited higher excitation pressure (1−qP) under the current light environment, leading to increased stress even at low relative light intensities of 3%–17%. A model illustrating the dependence of photosynthetic physiological parameters on the photosynthetic photon flux density (PPFD) revealed that 1−qP significantly decreased with an increasing LMA, while the electron transfer rate (ETR) and non-photochemical quenching (NPQ) significantly increased. Additionally, regardless of the LMA, 1−qP reached near saturation (≈1.0) at a PPFD of 1000 μmol m−2 s−1, likely owing to the inefficient consumption of excess energy by electron transfer, as indicated by the low maximum ETR (approximately 25 μmol m−2 s−1). These findings suggest that although A. sachalinensis exhibits high sensitivity to photoinhibition, a high LMA may reflect physiological acclimation to forthcoming elevations in light exposure, thereby reducing the susceptibility to photoinhibition at present and in the future.

Steatosarcopenia: A New Terminology for Clinical Conditions Related to Body Composition Classification

Body composition analysis focuses on measuring skeletal muscle mass and total body fat. The loss of muscle function and mass is related to clinical conditions such as frailty, increased risk of falls, and prolonged hospitalizations. Despite the relevance of the definition of sarcopenic obesity, there is still a gap in the monitoring of patients who have the combination of sarcopenia and myosteatosis, regardless of the presence of obesity. Therefore, we propose a new nomenclature, steatosarcopenia, a condition characterized by the loss of mass or skeletal muscle strength and performance associated with the excessive deposition of ectopic reserve fat in muscle tissue, in the same individual, not necessarily related to excess fat total body mass. A greater understanding of this condition may assist in developing strategies for preventing and treating metabolic diseases.

Effect of body mass index on quadriceps angle and tibial torsion in school-aged children

BackgroundThe prevalence of excessive body mass (BMI) is increasing in pediatric population. Accordingly, the number of musculoskeletal problems in this population is also likely to increase. The quadriceps angle (Q-angle) is a clinical measure used to measure knee alignment in relation to the hip, femur, and tibia, as well as evaluating alignment of the patella. Tibial torsion (T.T) is an important morphological feature of human tibia. The aim of that study was to study the relationship between the Q-angle and TT in children 8 to 12 years old, the effect of BMI on Q-angle and T.T, and the difference in Q-angle and TT between dominant and non-dominant side.Results“Seventy-five children from primary schools” were enrolled in the study and allocated into 3 groups (25 subjects in each group), according to BMI: group I (normal weight = 25), group II (overweight = 25), and group III (obese = 25). The mean value of age of groups I, II, and III was 10.35 ± 1, 10.74 ± 1.2, and 10.17 ± 1.18 years respectively; the mean value of weight was 29.88 ± 3.94, 43.68 ± 6.55, and 50.06 ± 10.44 kg respectively; the mean value of height was 135.28 ± 7.63, 143.2 ± 8.85, and 140.72 ± 9.3 cm respectively; and the mean value of BMI was 16.22 ± 1, 21.18 ± 1.4, and 25.17 ± 2.67 kg/m2. The number (%) of boys in groups I, II, and III was 15 (60%), 18 (72%), and 17 (68%) respectively and of girls was 10 (40%), 7 (28%), and 8 (32%) respectively.The significant values were Q-angle and TT. Data were expressed as mean ± SD. ANOVA was used to compare between subjects’ characteristics of the groups. Kolmogorov-Smirnov test was used for testing normality of data distribution. One-way MANOVA was used to compare parametric variables (Q-angle and TT) between the two groups. Compared with normal weight children, there was statistically significant increase in Q-angle and TT angle in overweight and obese children.ConclusionAny change in BMI would eventually lead to change in both Q-angle and TT angle. The greater the BMI values, the greater the values of Q-angle and TT angle.