Loss Factor Research Articles

Effect of screw insertion depth into fractured vertebrae in the treatment of thoracolumbar fractures

PurposeThe study’s objective was to assess the effect of the screw insertion depth into fractured vertebrae in treating thoracolumbar fractures.Materials and methodsThis was a retrospective analysis of 92 patients with thoracolumbar fractures from December 2018 to February 2020. Patients had AO type A2, A3 thoracolumbar fractures. The patients were divided into two groups according to the screw insertion depth. The vertebral wedge angle (VWA), Cobb angle (CA), anterior vertebral body height (AVBH), middle vertebral body height (MVBH), visual analog scale (VAS) score, and Oswestry Disability Index (ODI) were compared preoperatively and at one week and 12 months postoperatively. The correlation between Vertebral height loss and potential risk factors, such as sex, age, BMD and BMI was evaluated.ResultsCompared with the preoperative data, the postoperative clinical and radiographic findings were significantly different in both groups, But no significant difference between the two groups at 1 week. At 1 year postoperatively, there was a significant difference in the CA (p < 0.0001), VWA (p = 0.047), AVBH (p < 0.0001), MVBH (p < 0.0001), VAS score (p < 0.0001), and ODI (p < 0.0001) between the two groups, Except for age, bone density and other influencing factors the long screw group had better treatment results than the short screw group.ConclusionA longer screw provides greater grip on the fractured vertebral body and stronger support to the vertebral plate. The optimal screw placement depth exceeds 60% of the vertebral body length on the lateral view.

A study on BaTiO3 – NiFe2O4 composite; microstructure, multiferroic and magnetodielectric properties

The lead-free x NiFe2O4 – (1-x) BaTiO3 (x = 0, 0.05, 0.1, 0.15) multiferroic composites were prepared via the solid-state sintering technique. Microstructure, multiferroic, and magnetodielectric properties of composites were investigated. According to the XRD data (from x = 5 to 15 wt%), the tetragonality factor (cT/aT) and unit cell volume of the BaTiO3 (BTO) crystal system diminished. Based on SEM images, ferromagnetic NiFe2O4 (NFO) grains are uniformly dispersed in the ferroelectric BTO matrix without additional reaction in the interfaces of two phases. The highest values of dielectric (dielectric constant (εr) ∼ 1905 and dielectric loss factor (tan δ) ∼ 0.049) and ferroelectric properties (saturation polarization (PS) ∼ 13 μC/cm2 and remnant polarization (Pr) ∼ 10 μC/cm2) are attained for x = 5 wt% due to the lowest NFO (non-ferroelectric) concentration. Also, with increasing ferrite concentration (up to 15 wt%), the ferroelectric properties of the composites show a gradual decrease. The saturation magnetization (MS) values rise due to increasing ferrite concentration (from 2 to 5 emu/g for x = 5 to 15 wt%). Moreover, coercivity (HC) drops from 150 to 110 Oe. The simultaneous observation of the ferroelectric and ferromagnetic characteristic hysteresis loops confirmed the multiferroic effect for x = 5, 10, and 15 wt%. The highest magnetodielectric constant (3 %) is obtained for x = 15 wt% multiferroic composite at the applied magnetic field of 6 kOe.

Enhancing electromagnetic interference mitigation: A comprehensive study on the synthesis and shielding capabilities of polypyrrole/cobalt ferrite nanocomposites

In a society increasingly infiltrated by digital and networking technologies, designing electromagnetic interference (EMI) shielding materials is critical for safeguarding sensitive electronic equipment and ensuring the smooth functioning of essential communication networks. This study focuses on the optimization of the properties of cobalt ferrite (CoFe2O4)/polypyrrole (PPy) nanocomposites made by in-situ polymerization used for electromagnetic (EM) shielding based on their magnetic and dielectric losses. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and vector network analyzer (VNA) were employed to study the materials' physical and chemical characteristics. The findings demonstrate that the magnetic and electric properties of the materials composed of CoFe2O4 and PPy are substantially altered by the integration of CoFe2O4 and PPy. Adding PPy to CoFe2O4 reduces the real and imaginary parts of magnetic permeability, and the conductivity, dielectric constant, and dielectric loss are increased. These effects are advantageous for EM shielding applications. The high electromagnetic shielding performance mainly results from the enhanced interfacial polarization induced by interface region among CoFe2O4 and PPy molecules. The influence of the PPy matrix in altering the dielectric and magnetic loss factors (tanδE and tanδM) of the embedded ferrite particles is pronounced. Although CoFe2O4 shows excellent attenuation characteristics, it cannot optimally match impedance with free space, particularly at higher frequencies. In addition, material thickness and shielding efficiency adjust the reflection loss (RL) performance. The prepared composites can attenuate more than 95 % of the incident electromagnetic waves. This study emphasizes the benefits of employing composite materials in EMI shielding designs and the combined advantages of conductive and magnetic materials.

Optimizing ZnSe nanorods with La doping for structural, electrical, and dielectric properties in device applications

Nano-materials, pure Zinc Selenide (ZnSe), and rare earth (Lanthanum) doped ZnSe (Zn1-xLaxSe, x = 0.00, 0.02, 0.04, 0.06) were synthesized via a facile and low-cost hydrothermal method. X-ray diffraction (XRD) demonstrated that the nanoparticles grow in cubic crystal phase with high degree crystallinity, and the measured crystallite size of La-doped ZnSe ranges from 31.95 to 31.11 nm. Mitigation in crystallite size was observed with the inclusion of La and enhancement in the lattice constant ‘a’ from 5.6565 Å to 5.6818 Å. Morphological study (FESEM) depicts synthesized materials' morphologies as nanorods. The FESEM images indicate the random distribution of the nanorods across the crystal lattice, regardless of the accumulation of the nanorods, showing lumps in the synthesized material sample. The estimated grain size of pure ZnSe nanorods ranges from 137.6 to 496.9 nm. Electrical features revealed that direct current (DC) electrical conductivity ‘σdc’ enhances with temperature, affirming the semiconducting behavior of the materials. Increased lanthanum content enhances the ‘σdc’ from 3.08 × 10–5 (Ω cm)-1 to 5.94 × 10–5 (Ω cm)-1 at 303 K while lessening the activation energy value from 0.134 to 0.104 eV. Dielectric features, including relative permittivity (ε'), loss factor or dielectric loss (ε''), tangent loss (tanδ), as well as AC conductivity (σac), indicate a direct proportionality with temperature, and elevated values of all the dielectric parameters are noted with La-doping. An increase in dielectric constant with doping concentration displayed that the prepared nanocrystals have valuable dielectric and capacitive behavior. The outcomes of electrical and dielectric features display that the prepared nanorods have vital characteristics for developing optoelectronic devices, solar cells, photocatalysts, and light-emitting diode applications.

Fatigue analysis on flax-epoxy composites: insights and implications

This study investigates the performance of flax fiber and epoxy resin composites, focusing on fatigue testing, which is scarcely reported in the literature. Fatigue behavior is evaluated under full reverse bending loading conditions: R = −1. Apart of the definition of the classic S-N curve, the analysis deeply investigated the evolution of the hysteresis leaf generated during each cycle over the entire fatigue life. This approach allows evaluating interesting parameters such as the evolution of the loss factor and the apparent modulus over life, being these informations fundamental for practical application of natural-fiber composites in engineering applications.

Dielectric spectroscopy technology combined with machine learning methods for nondestructive detection of protein content in fresh milk.

To quickly achieve nondestructive detection of protein content in fresh milk, this study utilized a network analyzer and an open coaxial probe to analyze the dielectric spectra of milk samples at 100 frequency points within the 2-20GHz range, focusing on the dielectric constant ε' and the dielectric loss factor ε''. Feature variables were extracted from the full dielectric spectra using the successive projections algorithm (SPA), uninformative variables elimination (UVE), and the combined UVE-SPA method. These variables were then used to develop partial least squares regression (PLSR), support vector machine (SVM), decision tree (DT), random forest (RF), and least squares boosting (LSBOOST) models for predicting protein content. The results showed that ε' decreased monotonically with increasing frequency, while ε'' increased monotonically. The UVE-SPA method for feature extraction demonstrated superior performance, with the UVE-SPA-PLSR model being the best for predicting milk protein content, achieving the highest RC 2=0.998 and RP 2=0.989 and the lowest RMSEC=0.019% and RMSEP=0.032%. This study provides a theoretical reference for evaluating milk quality and developing intelligent detection equipment for natural milk.

Static and dynamic mechanical properties of aluminum nitride-silicon carbide whisker composites

AlN composites reinforced with SiC whiskers and Y2O3 sintering aids were fabricated using the hot-pressing technique to investigate static and dynamic mechanical properties. Microstructure analysis revealed that increasing SiC whisker content yielded grain refinement and decreasing relative density. The Vickers hardness increased from 10.29 to 14.47 GPa, while the fracture toughness improved from 3.03 to 4.39 MPa·m1/2 with 30 wt% SiC whiskers. A numerical approach for evaluating the dynamic modulus and loss factor is presented utilizing the wave propagation characteristics. The dynamic properties showed decreasing dynamic modulus and increasing loss factor with higher SiC content, attributed to increased porosity and interphase boundaries. Thermal conductivity, however, decreased from 139.53 to 49.95 W/m·K as SiC whisker content increased, primarily due to enhanced phonon scattering at grain and interphase boundaries. These findings suggest that AlN-SiCw composites are promising candidates for heat dissipation ceramic substrates, which offer superior mechanical strength and reliable thermal management.

Association Between Scalp Microbiota Imbalance, Disease Severity, and Systemic Inflammatory Markers in Alopecia Areata.

Alopecia areata (AA) is an autoimmune disease causing non-scarring hair loss, with both genetic and environmental factors implicated. Recent research highlights a possible role for scalp microbiota in influencing both local and systemic inflammatory responses, potentially impacting AA progression. This study examines the link among scalp microbiota imbalances, AA severity, and systemic inflammation. We conducted a cross-sectional study with 24 participants, including patients with AA of varying severities and healthy controls. Scalp microbial communities were analyzed using swab samples and ion torrent sequencing of the 16S rRNA gene across multiple hypervariable regions. We explored correlations among bacterial abundance, microbiome metabolic pathways, and circulating inflammatory markers. Our findings reveal significant dysbiosis in the scalp microbiota of patients with AA compared to healthy controls. Severe AA cases had an increased presence of pro-inflammatory microbial taxa like Proteobacteria, whereas milder cases had higher levels of anti-inflammatory Actinobacteria. Notable species differences included abundant gram-negative bacteria such as Alistipes inops and Bacteroides pleibeius in severe AA, contrasted with Blautia faecis and Pyramydobacter piscolens predominantly in controls. Significantly, microbial imbalance correlated with AA severity (SALT scores) and systemic inflammatory markers, with elevated pro-inflammatory cytokines linked to more severe disease. These results suggest that scalp microbiota may play a role in AA-related inflammation, although it is unclear whether the shifts are a cause or consequence of hair loss. Further research is needed to clarify the causal relationship and mechanisms involved.

Realization of Secure Robotic Brain Via Programmable Metasurface with Robust High‐Order BIC

AbstractTerahertz waves can be widely used for short‐range communication in complex indoor environments and non‐destructive object detection applications. Metasurfaces are widely used in terahertz sensing and communication devices because they can modulate terahertz waves in multiple dimensions. Metamaterial robot brain can utilize metasurfaces' powerful direct modulation ability to achieve sensing and communication functions. The metasurface devices realized based on Dynamic Heterogeneous Redundancy (DHR) architecture can improve the confidentiality and security of terahertz wave wireless communication. While the intrinsic ohmic loss and quality factor of usual metallic metamaterials are usually low, the concept of bound states in the continuum (BIC) has been proposed for stronger terahertz‐matter interactions. Among them, high‐order BICs are of interest because of their strong robustness to structural defects. Therefore, an aluminium‐graphene hybrid metasurface with high‐order BIC is proposed. We have the principle of excitation of high‐order BICs is investigated and creatively proposed with high robustness realized using the magnetical EIT effect. The robustness of the high‐order BIC is also utilized to design security hardware based on DHR architecture. The designed secure hardware can satisfy the demand for an intelligent robotic brain to the internal terahertz wave confidential wireless communication.

Thermal/vibration characteristics of additional damping structures with entangled metallic wire material under high temperature environment

In modern engineering practice, the simultaneous exposure to high temperatures and vibrations can threaten the security of the structure. In this paper, a novel additional damping structures with entangled metallic wire material (EMWM) are proposed and its vibration characteristics at high temperature are investigated. Firstly, a thermal/vibration coupling test platform of additional damping structures is designed and constructed, and a high-temperature vibration pickup method is adopted to extract the response signals. On this basis, the 5–400Hz frequency sweep tests are carried out under the unilateral constraint condition. The effects of excitation magnitude, ambient temperature and EMWM thickness on the vibration parameters are analyzed. The vibration performance is evaluated by modal identification and loss factor by half-power method. The results show that the damping performance of the constrained damping structure and insertion damping structure is better than that of the free damping structure under different excitation levels; the increase of the ambient temperature generates a greater influence on the vibration damping performance of the structure, but it still has a good stability; the amplitude change of the structure is more apparent through the increase of EMWM thickness, and the vibration damping performance is more superior. Under extreme engineering environments, a new approach to plate damping structures is provided that still maintains excellent performance.

Targeting CD3-CD16+CD56+ NK Cells and NK Cell Activity by Intralipid in the Management of Reproductive Failure

Immunological risk factors in recurrent pregnancy loss include autoantibodies, alterations in NK cell number and function, regulatory T cells, the human leukocyte antigen system (HLA), etc., where the treatment options aim to regulate immune dysfunction. Intralipid is a synthetic product traditionally used as a dietary supplement consisting of soybean oil combined with refined egg phospholipids. It has been shown that intralipid exerts physiologic activities, including altering immunological functions, that may benefit patients with certain types of infertility. In this review, we summarize the current state of the art of targeting NK cells and NK cell activity in women with implantation failure or/and recurrent pregnancy loss. We focus on intralipid mechanisms of action and outcomes of clinical trials regarding the efficacy and safety of intralipid infusions in women with reproductive failure. More studies are needed to reveal all the aspects of the safety and effectiveness of intralipid administration in reproductive failure treatment.

Free vibration analysis of sandwich shells with cutouts: An experimental and numerical study with artificial neural network modelling

This article investigates the free vibration and damping characteristics of cylindrical sandwich shells with cutouts using both experimental and numerical approaches. The effects of cutout shape, size, and position on the dynamic response of cylindrical sandwich shells are explored. Moreover, Artificial Neural Network (ANN) models are constructed to predict the dynamic behavior of the sandwich shell with a cutout. A user-friendly application, Sandwich Shell Vibration Analysis (SSVibA), is developed, incorporating the ANN models to predict the non-dimensionalized natural frequencies and modal loss factors of the sandwich shell under different shell geometries, boundary conditions and cutout configurations. The objective of the present research is to advance the understanding of the dynamic behavior of sandwich structures by integrating experimental investigations, numerical analyses, and ANN modeling.

Evaluation of wind potential and economic prospects in the southern regions of Morocco with MERRA-2 and ERA5

Meteorological reanalyses are generating interest in the modelling of wind energy production. This study provides a comparison between ERA5 and MERRA-2. Two regions in Morocco were studied: Laayoune-Sakia-El-Hamra (22 sites) and Dakhla-Oued-Eddahab (17 sites). Among the 150 wind turbines tested, the two most efficient ones were identified for each site. The results show that MERRA-2 outperforms ERA5 in several aspects, including scatter plots and R2 correlation. Wind potential and economic viability were evaluated for each of the 39 sites, incorporating a loss factor of 26.71% and applying Weibull parameters to precisely characterize each site. The analysis reveals that a few sites stand out for their high wind speeds, significant power densities and a capacity factor reaching 54.37%. Economically, the cost of electricity, ranging between $ 0.012 and $ 0.023 per kWh, is particularly favourable for wind energy production.

A retinal detachment based strabismus detection through FEDCNN

Ocular strabismus, a common condition in the present generation is an absolute risk factor for amblyopia and blinding premorbid visual loss. Despite the availability of new optometry tools with eye-tracking data, the issues persist in attaining accuracy and reliability in diagnosing strabismus. These two concerns are specifically accommodated in this study by the proposed novel approach that involves CNNs with eye-tracking datasets from subjects. The presented work aims to improve the accuracy of diagnostics in ophthalmology utilizing the integration of the further proposed algorithms into an automatic strabismus detection system. For this purpose, the proposed FedCNN model combines the CNN with eXtreme Gradient Boosting (XGBoost) and uses the Gaze deviation (GaDe) images to capture dynamic eye movements. This method tries to make the feature extraction as accurate as possible in its best working state to enhance the diagnosis precision. The model proves to be accurate, reaching 95.2%, which is even more prominent because of the more or less detailed connection layer of the CNN, which is used for the selection of features designated for such tasks of strabismus recognition. The presented method has the potential of shifting the approach to diagnosing diseases of the eyes in more or less half of the patients.

Bone density as a risk of early loss of correction after percutaneous posterior spinal fixation for traumatic thoracolumbar fracture: a study on the usefulness of Hounsfield unit values on computed tomography scan.

Vertebral Hounsfield unit values on computed tomography scan (CT values) have been found to be correlated with bone density measured using dual-energy X-ray absorptiometry. We hypothesized that low preoperative CT values are risk factors for early loss of correction after percutaneous posterior spinal fixation (PPSF). This study aimed to evaluate the usefulness of measuring preoperative CT values. In total, 104 patients underwent PPSF due to traumatic thoracolumbar fracture. Among them, 53 with a range of fixation that was within two vertebrae above and below the fractured vertebra were selected. CT values were measured preoperatively from the most cephalad vertebrae on the fixed vertebrae. Vertebral wedge angle (VWA) and local kyphosis angle (LKA) were measured before and after surgery. participants were classified into progression (P) and nonprogression (NP) groups. The P group comprised patients with LKA progressing > 10° from the immediate postoperative period to 3months postoperatively. Meanwhile, the NP group included patients without progression. Eight (15.1%) patients were included in the P group. The vertebral CT values were 102.2 ± 36.7 in the P group and 162.4 ± 59.7 in the NP group (p < 0.01). The pedicle CT values were 114.4 ± 45.9 in the P group and 170.8 ± 72.3 in the NP group (p < 0.05). At 2weeks postoperatively, VWA and LKA of the P group progressed to 9.8° ± 7.0° and 10.9° ± 7.6°, respectively. CT values can predict progressive loss of correction after PPSF.

8305 Assessing The Relationship Between Oral Health And Bone Disease Among Post-menopausal Women

Abstract Disclosure: N. Tahir: None. S. Ahmad: None. K. Batra: None. A. Gupta: None. K.E. Izuora: Research Investigator; Self; Novo Nordisk. Background: Menopause is associated with significant bone loss and worsening oral health, especially periodontal disease (PD). The purpose of this study was to understand the relationship between oral health and bone loss and the factors that influence this relationship. This will help better understand their pathophysiology and provide guidance for more appropriate care. Methods: ​​This cross-sectional study included post-menopausal women undergoing routine bone density evaluation at a diagnostic radiology center. After participants signed informed consent, histories were collected via an investigator-administered questionnaire, the oral cavity was inspected for teeth loss and PD, and a bone density assessment, interpreted by a radiologist, was obtained. The significance level was set at 5% and data were analyzed using chi-square and logistic regression tests. Results: In a sample of 100 eligible participants, the mean age and body mass index (BMI) were 68.17 ± 8.33 years and 29.59 ± 6.13 kg/m2 respectively. Twenty-three participants (23.0%) had T2DM, 29 (29.0%) had &amp;lt; 20 natural teeth and 17 (17.0%) had normal bone mineral density. In an unadjusted simple logistic regression, age, BMI, race/ethnicity, number of natural teeth, history of PD, and history of osteoporotic fracture were associated with bone loss. However, in the binary logistic regression, the only significant predictors of bone loss included age (aOR 1.171, p&amp;lt;0.001), BMI (aOR 0.763, p&amp;lt;0.001), and the history of osteoporotic fractures (aOR 21.273, p=0.021). Conclusion: Clinical variables associated with bone loss in our study included older age, lower BMI, and history of osteoporotic fracture. These are established risk factors for bone loss. Although unadjusted results suggest a relationship between oral health measures and bone loss, these relationships were not present when other factors were included in a multivariate model. These findings suggest PD by itself may not be a risk factor for bone loss but may reflect the similarity in the risk factors for both conditions. Presentation: 6/3/2024

A Novel Approach of the Viscoelasticity of Axially Functional Graded Bar and Application of Harmonic Vibration Analysis of an Isotropic Beam as Support

The use of smart materials and passive controllers in modern technologies has stimulated the study of vibration in elastic systems with viscoelastic damping. It is also possible to create components with precise material distribution coefficients and distinct properties, such as Functionally Graded Materials. This work investigates the resonant frequency characteristics of a beam supported at its ends by Axially Functionally Graded (AFG) viscoelastic bars using the finite element method. The set of equations governing motion is obtained by assuming Euler–Bernoulli beam theory for the beam and bar theory for the bars using Lagrange’s equations. The material properties of the functionally graded bar is assumed to vary through the length according to the power law distribution. The longitudinal loss factor values are used to define the internal damping coefficient, which is also dependent on the Young’s modulus value varying along the bar. The effects of the length-varying material properties and internal damping of the FG support bars on the force transmission TR and frequency parameters λ are examined in detail. No study has been found in the literature on the vibration of viscoelastic FG bar-supported beams subjected to a harmonic force at the centre point. It is shown that using bars formed with combinations of different materials considering material damping will be useful to keep the vibration level and force transmission at a certain value and control the frequency parameters.

Measured and predicted sound transmission through a laboratory concrete floor

The direct sound transmission through a simple, massive, homogeneous building element with and without lining is investigated experimentally and compared with analytical and empirical models from the literature. A 150 mm thick concrete floor and a 100 mm thick floating floor were measured in the floor transmission facility of the National Research Council Canada, i.e. without flanking sound transmission. In addition to the sound reduction index and the normalized impact sound pressure level, loss factors, radiation efficiencies, and mean squared velocities were recorded in the laboratory. The measured data is compared to established models of sound transmission. A focus is placed on the calculation model of ISO 12354-1 (Appendix B), which uses calculated radiation efficiencies and loss factors to predict the sound reduction index of heavy, homogeneous building elements. Some difficulties with the calculation model and the examples in the standard are discussed. In principle, the results in this study show that the calculation model of ISO 12354-1 gives good estimates when the correct input parameters are used. However, deviations between the calculated and the measured loss factors and radiation efficiencies have large effects on the accuracy of the estimates, particularly in the region around the coincidence frequency.

Recycled plastics based impact noise resilient layer development

Sustainability and the carbon footprint reduction is commonly associated with recycling and secondary use of materials, for example also in the building construction industry. For decades, experts have been dealing with this topic across the entire spectrum of the development of building structures. One of the areas where soft recycled materials find suitable application is the area of building acoustics with a focus on impact noise attenuation. This contribution focuses on resilient layers dedicated for lightweight floating floors. This type of flooring is very often used in the reconstruction of apartments in apartment buildings. There is usually no possibility to realize heavy floating floors or for static reasons or reasons of the structural height of rooms or door openings. The work focuses on the development of floor underlayer mats based on recycled material in several variants. These were experimentally compared with conventional materials used in practice as the so-called impact sound insulation layers under laminate floors in terms of improving the impact noise insulation as well as the dynamic stiffness and the loss factor.

Wooden multistorey acoustic test facility for vibration reduction indices measurement on different junctions of floor decking used to reduce flanking transmissions

FCBA, CSTB and Cerqual joint forces together with the French acoustic wood technical commission, to create in 2020, an in-situ measurement mockup: the "Maquette Acoustique Bois". The mockup is a CLT based building of three floors construction, with four rooms on each level. Measurements from junction characterization to air-borne and impact sound insulations can be performed. In this paper the "Maquette Acoustique Bois" is used to measure vibration reductions levels indexes Kij, in different configurations, where smart building systems junctions are implemented to reduce flanking transmissions. Measurement results presented are generated from 4 types of junctions in between 2 rooms. The load bearing structure is Cross Laminated Timber (CLT). The measurement strategy is Statistical Energy Analysis (SEA). SEA involves cutting the structure into subsystems and decomposing the spectrum into third-octaves or octaves. In this way, the exchange of energy flow in the substructures can be analyzed. The parameters that govern vibrational transmission between subsystems are damping and coupling loss factors and can be identified experimentally by reversing the problem. The approach is, first, based on sub-structuring strategy of structure; second, on experimentally measured coupling and damping loss factors; third, on extracting vibration level difference one by one all flanking passes.