Changes In Strength Research Articles

Six-month rehabilitation following surgical hip dislocation for femoroacetabular impingement restores the preoperative strength of most hip muscles, except for external rotators

Abstract The aim of this study was to evaluate the bilateral changes in hip muscle strength after a 6-month rehabilitation period for patients undergoing surgical hip dislocation (SHD) to treat femoroacetabular impingement syndrome (FAIS). We conducted a retrospective analysis on a cohort of 22 patients (mean ± SD age: 26 ± 7, 68% male) who underwent SHD for FAIS between March 2020 and January 2023 at La Tour Hospital. Bilateral isometric strength of eight hip muscle groups (abductors, adductors, hamstrings, quadriceps, extensors, flexors, internal, and external rotators) was assessed using a handheld dynamometer before surgery, and at 3 and 6 months postoperatively. After 6 months of rehabilitation, only the external rotators were weaker compared to preoperative levels (−13% ± 23%, P = .021). Strength levels were similar to preoperative levelsfor adductors (−2% ± 21%, P = .309), internal rotators (0% ± 25%, P = .444), quadriceps (0%± 23%, P = .501), hamstrings (7%± 20%, P = .232), extensors (7%± 19%, P = .336), flexors (8%± 34%, P = .781), and abductors (8% ± 25%, P = .266). At 6 months, 59% (abductors) to 82% (adductors) of patients did not achieve a clinically relevant strength improvement (>15%) compared to their preoperative status for aforementioned muscles. Additionally, 50% of the cohort experienced a clinically relevant loss of strength in the external rotators at 6 months post-surgery. To conclude, after SHD, most FAIS patients regained their preoperative strength for all muscle groups except the external rotators with a 6-month rehabilitation program. However, the effectiveness of the rehabilitation protocol varies on an individual level.

Numerical Modeling of Engineering-Scale Jointed Coal Mass and Confining Pressure Effect

In coal masses, joints serve as crucial components influencing mechanical responses and failure mechanisms. The joint distribution complicates the acquisition of physical parameters for engineering-scale coal masses, and traditional laboratory or in situ tests often suffer from inaccuracies and high costs. Therefore, examination of the dynamic properties of engineering-scale coal mass is generally performed by numerical simulations. This paper proposes a model construction approach using two-dimension Particle Flow Code (PFC2D) software to study the mechanical properties of engineering-scale jointed coal mass, addressing the limitations of conventional models by integrating scale effects, accuracy, and computational efficiency. Firstly, the distribution characteristics and mechanical parameters of the joints in the coal mass were obtained based on field statistics and laboratory experiments. The parameters of the laboratory-scale model were calibrated by the numerical matching method. The discrete element model for the engineering-scale coal mass was constructed by the step-by-step matching method. The confining pressure effect on the coal mass under a biaxial loading condition was studied, while the strength change, fissure evolution, and failure mechanism under different confining pressures and fissure degrees were investigated. Based on the simulation results, a quantitative relationship was established between the mechanical parameters, fissure degree, and confining pressure under compression conditions. Ultimately, the failure zone ahead of the working face and the distribution of the abutment pressure were assessed using the mechanics parameters of coal masses with diverse joint distributions.

Contribution and evolution of respiratory muscles function in weaning outcome of ventilator-dependent patients

BackgroundThe present study was designed to investigate the evolution and the impact of respiratory muscles function and limb muscles strength on weaning success in prolonged weaning of tracheotomized patients. The primary objective was to determine whether the change in respiratory muscles function and limb muscles strength over the time is or is not associated with weaning success.MethodsTracheotomized patients who were ventilator dependent upon admission at a weaning center were eligible. Diaphragm function was assessed with the phrenic nerve stimulation technique and with ultrasound to measure the diaphragm thickening fraction (TFdi) and diaphragm excursion (EXdi). Global respiratory muscle function was assessed with the maximal inspiratory pressure (MIP) and the forced vital capacity (FVC). Limb muscle strength was measured with the Medical Research Council Score (MRC). Measurements were made on a weekly basis. Patients were compared according to their outcome at discharge: complete weaning, partial weaning or death.ResultsAmong the 60 patients who were enrolled, 30 patients finally achieved complete weaning, 20 had partial weaning and 10 died. At 6 months, 6 patients were lost of follow-up, 33 achieved complete weaning, 10 had partial weaning and 11 died. In median, 2 (1–9) assessments were performed per patient. Diaphragm dysfunction was present in all patients with a median Ptr,stim of 5.5 cmH2O (3.0–7.5). Ptr,stim, MIP, TFdi and EXdi at admission were not different between patients who achieved complete weaning and their counterparts. At discharge of the weaning center, MIP, Ptr,stim and EXdi significantly increased in patients who achieved complete weaning. The MRC score significantly increased only in patients with complete weaning. At discharge, diaphragm dysfunction was highly prevalent even in patients with complete weaning (Ptr,stim < 11 cmH2O in n = 11 (37%)).ConclusionRespiratory muscle function and limb muscles strength are severely impaired in patients with prolonged weaning from mechanical ventilation. Significant improvement of diaphragm ultrasound indices was associated with successful weaning from mechanical ventilation and ICU-acquired weakness upon admission was significantly associated with good outcome suggesting that it was an amendable determinant of weaning failure in this population.

Influence of CFBC Fly Ash Chemical Composition and Mechanical Activation on the Properties of Geopolymer

Circulating fluidized bed combustion (CFBC) fly ash has the potential as a precursor to making geopolymer concrete because of its rich silica and alumina content. However, there is a problem in utilizing CFBC fly ash caused by its chemical and physical properties that differ from the widely used pulverized coal combustion (PCC) fly ash. CFBC fly ash has a higher water requirement than PCC fly ash due to its angular particle shape, and higher sulfur and lime contained also caused a different reaction in the geopolymer system. Mechanical activation by milling the CFBC fly ash could decrease the water requirement in the mixture and make good quality CFBC fly sh-based geopolymer concrete. Three CFBC fly ash samples from different power plants in Indonesia with different chemical compositions were used in this research. The first had a low lime and no sulfur content, the second had high lime and no sulfur content, and the third had high lime and sulfur content. The milling process using a ball mill for two hours decreased the water requirement, as shown in the lower normal consistency of the fly ash. The reactivity also was increased, shown by the faster initial setting time. Besides its higher reactivity, lower water requirement increased the compressive strength of geopolymer mortar produced. This study also showed that the existence of calcium and sulfur content in the CFBC fly ash could cause unexpected results shown by the change of initial setting time, water requirement, and compressive strength.

Goose grubbing and warming suppress summer net ecosystem CO2 uptake differentially across high-Arctic tundra habitats.

Environmental changes, such as climate warming and higher herbivory pressure, are altering the carbon balance of Arctic ecosystems; yet, how these drivers modify the carbon balance among different habitats remains uncertain. This hampers our ability to predict changes in the carbon sink strength of tundra ecosystems. We investigated how spring goose grubbing and summer warming-two key environmental-change drivers in the Arctic-alter CO2 fluxes in three tundra habitats varying in soil moisture and plant-community composition. In a full-factorial experiment in high-Arctic Svalbard, we simulated grubbing and warming over two years and determined summer net ecosystem exchange (NEE) alongside its components: gross ecosystem productivity (GEP) and ecosystem respiration (ER). After two years, we found net CO2 uptake to be suppressed by both drivers depending on habitat. CO2 uptake was reduced by warming in mesic habitats, by warming and grubbing in moist habitats, and by grubbing in wet habitats. In mesic habitats, warming stimulated ER (+75%) more than GEP (+30%), leading to a 7.5-fold increase in their CO2 source strength. In moist habitats, grubbing decreased GEP and ER by ~55%, while warming increased them by ~35%, with no changes in summer-long NEE. Nevertheless, grubbing offset peak summer CO2 uptake and warming led to a twofold increase in late summer CO2 source strength. In wet habitats, grubbing reduced GEP (-40%) more than ER (-30%), weakening their CO2 sink strength by 70%. One-year CO2-flux responses were similar to two-year responses, and the effect of simulated grubbing was consistent with that of natural grubbing. CO2-flux rates were positively related to aboveground net primary productivity and temperature. Net ecosystem CO2 uptake started occurring above ~70% soil moisture content, primarily due to a decline in ER. Herein, we reveal that key environmental-change drivers-goose grubbing by decreasing GEP more than ER and warming by enhancing ER more than GEP-consistently suppress net tundra CO2 uptake, although their relative strength differs among habitats. By identifying how and where grubbing and higher temperatures alter CO2 fluxes across the heterogeneous Arctic landscape, our results have implications for predicting the tundra carbon balance under increasing numbers of geese in a warmer Arctic.

Influence of sand type on acid resistance and capillary absorption capacity

This study aims to investigate the effect of binary and ternary combinations of river sand (RS), crushed sand (CS) and dune sand (DS) on the physical and mechanical performance of concrete subjected to acidic curing environments. The RS was replaced by CS and DS in different mass proportions. The five concrete mixtures M21(RS), M04(0.6CS + 0.4DS), M10(0.2RS + 0.6CS + 0.2DS), M15(0.4RS + 0.6CS) and M16(0.6RS + 0.4DS) were prepared. The sorptivity was evaluated by measuring the sorptivity coefficient (S, cm*s-0.5) after 28 days of submersion in distilled water. Concrete specimens were submersed in distilled water, 5% sulfuric acid (H2SO4), and 5% hydrochloric acid (HCl) for up to 180 days in order to test their acid resistance. Visual inspection, changes in mass and changes in compressive strength were used to evaluate the specimens' resistance to acid attack. The results indicated that replacing RS with CS led to an increase in sorptivity, while replacing RS with DS resulted in a decrease. When both CS and DS were used in place of RS, acid resistance in 5% HCl solution decreased. In 5% H2SO4 solution, substituting RS with CS reduced mass loss, but replacing RS with both CS and DS weakened the concrete's compressive strength.

The Addition of Silica Nanoparticles to Type IV Dental Stone: Influence on the Diagonal Tensile Strength

Introduction: Various methods have been studied to improve the properties of dental stones; one of them is adding nanoparticles to dental stones. In this study, the effect of adding different percentages of silica nanoparticles (0.5, 1, 2, and 5) on the diagonal tensile strength of dental stone type IV was investigated. Materials and Methods: Silica nanoparticles with percentages of 0.5, 1, 2 and 5 physically were mixed with dental stone type IV and then with distilled water according to the factory's instructions (23 ml to 100 g at 23°C). The diagonal tensile strength was measured using a Universal Testing Machine. In order to compare the diagonal tensile strength in different groups, ONE WAY ANOVA test and SPSS.26 software were used. The significance level was considered 0.05. Results: The addition of silica nanoparticles to dental stone type IV had no effects on the diagonal tensile strength of this material (P = 0.237). Conclusion: It can be concluded that adding silica nanoparticles does not negatively affect the diagonal tensile strength, and all concentrations performed similarly. This suggests that any of these concentrations can be used without concern for changes in tensile strength. However, further investigation is needed to evaluate the impact on other properties.

Analysis of the Parity-Time Symmetry Model in the Receiver-Based Wireless Power Transfer

Parity-time (PT) symmetry has made encouraging progress in wireless power transmission (WPT), exhibiting significant advantages in terms of system robustness and transmission efficiency. However, there are still challenges that need to be addressed, particularly when classical schemes operate at a fixed frequency in the weak coupling region, where even minor changes in coupling strength can result in excessive current surges. This paper introduced a novel PT-symmetric WPT system featuring negative resistance constructed on the receiver side. We first established a theoretical framework for the classical two-coil PT-symmetric magnetically coupled resonant WPT system and subsequently extended it to incorporate the PT-symmetric WPT system with negative resistance on the receiver. This topological coil configuration facilitated stable power delivery over a broader range, with the capability of self-tuning frequency without requiring additional frequency modulation. This adaptability enabled the system to cater to diverse scenarios and opens up a novel avenue for practical applications of PT symmetry in WPT. Finally, we designed a 10 W prototype to demonstrate the effectiveness of our topology, and the experimental results aligned with our theoretical calculations, validating the feasibility and potential of our PT-symmetric WPT system.

Evaluation of Bonding Strength of Pipeline Coating Based on Circumferential Guided Waves

The anti-corrosion layer of the pipe provides corrosion resistance and extends the lifespan of the whole pipeline. Heat-shrinkable tape is primarily used as the pipeline joint coating material bonded to the pipeline weld connection position after heating. Delineating the bonding strength and assessing the quality of the bonded structure is crucial for pipeline safety. A detection technology based on nonlinear ultrasound is presented to quantitatively evaluate the bonding strength of a steel-EVA-polyethylene three-layer annulus bonding structure. Using the Floquet boundary condition, the dispersion curves of phase velocity and group velocity for a three-layer annulus bonding structure are obtained. Additionally, wave structure analysis is employed in theoretical study to choose guided wave modes that are appropriate for detection. In this paper, guided wave amplitude, frequency attenuation, and nonlinear harmonics are used to evaluate the structural bonding strength. The results reveal that the detection method based on amplitude and frequency attenuation can be used to preliminarily screen the poor bonding, while the acoustic nonlinear coefficient is sensitive to bonding strength changes. This study introduces a comprehensive and precise pipeline joint bonding strength detection system leveraging ultrasonic-guided wave technology for pipeline coating applications. The detection system determines the bonding strength of bonded structures with greater precision than conventional ultrasonic inspection methods.

Effect of biochar content and particle size on mechanical and water absorption properties of landscaping waste/polylactic acid composites

The high-value utilization of landscaping waste to produce wood-plastic composites provides a promising approach to waste management, yet remains a challenge. In this study, wood-plastic composites were prepared using landscaping waste and polylactic acid (PLA) through an extrusion-molding process, with biochar (BC) as the reinforcing material. First, the effects of biochar content (0.5 %, 1 %, 2 %, 3 %, 4 %) and particle size (100mesh, 300mesh, 800mesh, 1200 mesh) on the physico-mechanical and dynamic thermo mechanical properties of the composites were analyzed. A multivariate nonlinear model was employed to fit the flexural properties of the composites. Additionally, the water absorption properties were investigated under immersion conditions at three different temperatures (20°C, 35°C, 50°C). The results demonstrated that biochar significantly improved the interfacial compatibility between landscaping waste and PLA, enhancing the mechanical properties of this composite. When the biochar content was 1 % and particle size was 100 mesh, flexural strength reached 25.16 MPa, respectively, representing increases of 19.20 % over composites without biochar, while the change in impact strength was small. In addition, the water absorption process of composites with 1 % BC were well fitted by Fick's law. SEM morphology observation indicated that interfacial bonding was reduced after water absorption, which was consistent with the test results. Combined with Arrhenius equation and Fick's law, the water absorption model of the composites at each water immersion temperature was obtained, which can predict the water absorption behavior at 60°C.

Influence of Fresnel effects on the glossiness and perceived depth of depth-scaled glossy objects.

Fresnel effects, that is, shape-dependent changes in the strength of specular reflection from glossy objects, can lead to large changes in reflection strength when objects are scaled along the viewing axis. In an experiment, we scaled sphere-like bumpy objects with fixed material parameters in the depth direction and then measured with and without Fresnel effects how this influences the gloss impression, gloss constancy, and perceived depth. The results show that Fresnel effects in this case lead to a strong increase in gloss with depth, indicating lower gloss constancy than without them, but that they improve depth perception. In addition, we used inverse rendering to investigate the extent to which Fresnel effects in a rendered image limit the possible object shapes in the underlying scene. We found that, for a static monocular view of an unknown object, Fresnel effects by themselves provide only a weak constraint on the overall shape of the object.

Study on the Rheological Properties of Nano-SiO2 Composite Modified Basalt Mineral Fiber Asphalt Mortar

Abstract To investigate the impact of mineral fiber modification and dosage on the rheological properties of fiber asphalt mastic, basalt fiber surface roughness was enhanced using nano-SiO2 solution. Fiber asphalt mastic was prepared with a filler-bitumen ratio of 1.6 and fiber dosages of 0%, 1.3%, 2.6%, 3.9%, and 5.2%. The taper entry test, dynamic shear rheology test, and bending beam rheology test were employed to analyze the variations in taper entry, shear strength, complex modulus (G*), phase angle (δ), rutting factor (G*/sinδ), modulus of strength (S), and rate of change of strength (m) of the fiber asphalt mastic. The results indicate that the optimal dosage of mineral fibers in fiber asphalt mastic is 2.6%. Nano-modified basalt fibers significantly enhance the anti-shear capacity of asphalt mastic. The high-temperature stability of fiber asphalt mastic improves with increasing fiber dosage, but the improvement becomes negligible beyond a 2.6% dosage. The interfacial bonding layer formed by asphalt on the fiber surface enhances the high-temperature performance and stress dissipation at low temperatures, thereby improving low-temperature cracking resistance.

Does Unilateral High-Load Resistance Training Influence Strength Change in the Contralateral Arm Also Undergoing High-Load Training?

Training one limb with a high-load has been shown to augment strength changes in the opposite limb training with a low-load (via cross-education of strength), indicating that within-subject models can be problematic when investigating strength changes. This study examined if the cross-education of strength from unilateral high-load training could augment the strength changes in the opposite arm undergoing the same unilateral high-load training. 160 participants were randomized to one of four groups: (1) training on the dominant arm followed by the non-dominant arm (D + ND), (2) training on the dominant arm only (D-Only), (3) training on the non-dominant arm only (ND-Only), and (4) a non-exercise control. All exercise groups performed 18 sessions of unilateral high-load elbow flexion exercise over 6 weeks. Participants were compared for changes in 1RM strength and muscle thickness. Changes in strength of the non-dominant arm were greater in D + ND (2.7 kg) and ND-Only (2.6 kg) compared to D-Only (1.5 kg) and control (-0.2 kg), while the changes were greater in D-Only compared to control. The same finding was observed in the dominant arm. Only the arms being directly trained observed increases in muscle thickness. Unilateral high-load resistance training increased strength in the opposite untrained arm, without changes in muscle thickness. This cross-education of strength did not augment the strength changes in the contralateral arm undergoing the same unilateral high-load training. However, it does not necessarily indicate that within-subject models are methodologically sound to investigate strength change if both limbs are trained with a high-load.

Quadriceps strength can improve twelve months after opening wedge high tibial osteotomy and opening wedge distal tibial tubercle osteotomy, particularly after opening wedge high tibial osteotomy

BackgroundKnee osteoarthritis (KOA) is a globally prevalent condition leading to joint pain and disabilities. Surgical interventions such as opening-wedge high tibial osteotomy (OWHTO) and opening-wedge distal tuberosity osteotomy (OWDTO) aim to alleviate symptoms and delay disease progression. Quadriceps strength, crucial for knee function, may decline postoperatively, affecting patient outcomes. However, little is known about quadriceps strength variation after OWHTO and OWDTO. This study investigated changes in quadriceps strength before and after OWHTO and OWDTO. MethodsThis retrospective study included patients who underwent OWHTO or OWDTO between 2016 and 2022. Quadriceps strength and demographic and surgical data were collected preoperatively and at 6 and 12 months postoperatively. Statistical analyses were performed to compare changes in quadriceps strength over time. ResultsOf 120 knees, 52 (OWHTO, 27; OWDTO, 25) were included in this study. Quadriceps strength increased over 12 months post-OWHTO, significantly improving at 12 months compared to the preoperative and 6-month values. In OWDTO, the strength improved but not significantly. ConclusionsQuadriceps strength improved following OWHTO and OWDTO, with OWHTO showing significant enhancements. Future studies should investigate the relationship between quadriceps strength and functional outcomes and guide rehabilitation strategies for improved postoperative recovery.

Tracking research on the performance changes of S31042 steel under long term service

S31042 is widely used in ultra-supercritical units due to its excellent comprehensive performance at high temperatures. Tracking and monitoring research was conducted on as-received S31042 tubes and tubes in service for 13k hours, 31k hours, and 52k hours at 650 °C. The results show that as the service time increased, a large quantity of M23C6 phase precipitated along the grain boundaries, gathered and grew up into the bulk. This weakened of the grain boundaries, which facilitated crack propagation and significantly reduced the plasticity and toughness of the S31042 heat-resistant steel. After 13k hours of operation, the dispersion strengthening of the precipitated phase inside the grain and grain boundary led to a substantial increase in hardness, while there was no obvious change in strength. However, after 52k hours of operation, the dispersed precipitated phase within the grain slowly aggregated and grew, decreasing the effectiveness of dispersion strengthening. Consequently, both the high-temperature strength and hardness of the S31042 steel gradually decreased. As the service time increased, the continuously distributed and similarly sized M23C6 phases on the grain boundaries of S31042 developed into an inhomogeneous coarsening chain structure. Additionally, the appearance of nanoscale secondary NbCrN and M23C6 phases within the grain and their resulting precipitation strengthening effects were the main reasons for the significant change in S31042 hardness values. Based on these findings, the residual life of S31042 heat-resistant steel in service was predicted using an extrapolation method based on high-temperature creep rupture tests and the relationship model between hardness and the P function. A comparison of the L-M parametric life prediction results with the strength extrapolation life prediction results based on the standard creep rupture test shows that the creep rupture strength extrapolation method is slightly conservative. Therefore, the prediction results based on the hardness L-M parameter method, which is simple and easy to perform, can be used for preliminary life prediction.

Freeze-thaw resistance and deterioration mechanism of alkali-activated filling grouts prepared from full industrial solid wastes for tunnels

To promote the application of the proposed alkali-activated grout (AAG) prepared from full solid wastes in cold-zone tunnel projects located at high altitudes and latitudes, it is imperative to fully recognise its endurance to the repeated freezing and thawing in specific service scenarios. For this purpose, two groups of representative AAG were selected as subjects for this study, and a typical OPC-based grout was chosen as the control group. Freeze-thaw cycle tests were carried out on grout samples after 28 days of standard curing using the slow-freeze method to simulate the harsh service environment in cold regions. The deterioration impact of freeze-thaw cycling on the grout samples were evaluated by monitoring the changes in visual appearance, mass loss, mechanical strength, and damage coefficient after 20, 40, 60 and 80 freeze-thaw cycles. Furthermore, the deterioration mechanism of various grout samples under the action of freeze-thaw cycling was revealed by multi-technique characterization methods including X-ray diffraction (XRD), scanning electron microscope (SEM), and mercury intrusion porosimetry (MIP). The results show that at the same number of freeze-thaw cycles, the surface deterioration, mass loss and strength damage of AAG were obviously better than that of the OPC-based grout, suggesting that AAG exhibited greater resistance to freezing and thawing than the OPC-based grout. The mass loss ratio increased with the increase of the number of freeze-thaw cycles, following a roughly power function pattern. The deterioration in the flexural strength of grout samples caused by freeze-thaw cycles was more severe than the deterioration in their compressive strength. The gel products of AAG were mainly C-A-S-H and N-A-S-H, which showed stronger resistance to freeze-thaw damage than the gel products of the OPC-based grout, C-S-H and portlandite. Compared with the OPC-based grout, AAG samples possessed a denser microstructure with lower porosity and a smaller proportion of large-sized harmful pores, which was not favourable for the pore water holding and migration of during freeze-thaw cycling and the development of osmotic and frost heave stresses, thus providing better resistance to freezing and thawing. A variety of macroscopic characterisations and microstructural tests have demonstrated the good durability of AAG against the freeze-thaw cycles, which can serve as a scientific foundation for its future engineering uses.

Performance and Hydration Mechanism of Fly Ash Coal-Based Solid Waste Backfill Material Affected by Multiple Factors

Masses of coal-based solid waste like fly ash are emitted during coal combustion, with low utilization rate. Preparing fly ash into backfill material can not only improve waste utilization efficiency, but also repair the cracks in mining areas. In this research, the performance and hydration mechanism of fly ash coal-based solid waste backfill material were investigated through slurry performance experiment, mechanical strength test and microstructure analysis. Besides, the grouting effect of the backfill material was verified by grouting experiment. The research demonstrated that the increase of fly ash to cement ratio (from 0.5 to 1.5) improved the fluidity, viscosity and bleeding rate of the slurry, but prolonged the setting time. The adjustability of backfill material was good, and the compressive strength of specimen reached its highest value of 27.1 Mpa through changing multiple factors. The grouting effect of fine-grained macadam was better than that of coarse-grained macadam. The compressive strength and Young's modulus of the backfill material specimens containing 0.5-1cm macadam were 12.2% and 17.4% higher, respectively, than those with 1-2cm macadam. The primary hydration product of backfill material was gel, which structural elements were Si, Al and Ca. As the curing age increased, the distribution of the three elements became denser, and more gel was formed, corresponding to the changes in the compressive strength of the backfill material. The research offers material source and selection basis for backfilling cracks in mining areas and enhances utilization efficiency of coal-based solid waste.

Quantitative Muscle MRI to Monitor Disease Progression in Hypokalemic Period Paralysis.

Primary hypokalemic periodic paralysis (HypoPP) is a muscle channelopathy that can cause periodic paralysis and permanent weakness. Currently, little is known about how progressive this myopathy is. Natural history data for HypoPP can potentially answer the question of progressiveness and form the basis for outcome measures to be used in follow-up and emerging treatment trials. We aimed to describe the natural history of HypoPP and assess whether quantitative fat imaging is a valuable biomarker to monitor disease progression. In this prospective follow-up study, we examined disease progression using Dixon MRI to monitor changes in fat replacement of the muscle and stationary dynamometry to monitor changes in muscle strength. We included 37 persons (mean age 43 years, range 18-79 years) with HypoPP-causing variants in CACNA1S. Three participants were asymptomatic carriers, 22 had periodic paralysis, 3 had permanent weakness, and 9 had periodic paralysis in combination with permanent weakness. The median follow-up time was 20 months (range 12-25). We found that fat fraction increased in 10 of 21 examined muscles. An increase in the composite fat fraction of at least 1 muscle group was found in all symptomatic phenotypes. By contrast, we found no significant change in muscle strength. The results from this follow-up study support the use of quantitative muscle MRI to monitor subclinical disease progression in HypoPP in patients with and without attacks of paralysis.

Are Dental Prophylaxis Protocols Safe for CAD-CAM Restorative Materials? Surface Characteristics and Fatigue Strength

The surface of dental materials is exposed to various prophylaxis protocols during routine dental care. However, the impact of these protocols on the functional properties of the material’s surface remains unclear. This study investigates the influence of different dental prophylaxis protocols on the surface properties and their effect on the mechanical performance of CAD-CAM restorative materials. Discs (Ø = 15 mm, thickness = 1.2 mm) were fabricated from resin composite (RC, Tetric CAD), leucite-reinforced (LEU, IPS Empress CAD), lithium disilicate (LD, IPS e.max CAD), and zirconia ceramics (ZIR, IPS e.max ZirCAD MT). The materials were subjected to six prophylactic treatments: untreated (CTRL), prophylactic paste fine (PPF), prophylactic paste coarse (PPC), pumice stone (PS), air abrasion with sodium bicarbonate jet (BJ), and ultrasonic scaling (US). Biaxial flexural fatigue tests, along with fractographic, roughness, and topographic analyses, were conducted. No significant changes in fatigue strength were observed for RC, LD, and ZIR under any prophylaxis protocols. However, LEU subjected to BJ treatment exhibited significantly reduced fatigue strength (p = 0.004), with a 22% strength reduction compared to the monotonic test and substantial surface alterations. Surface roughness analyses revealed increased roughness for RC treated with PPF, PPC, and PS compared to CTRL (p &lt; 0.05), while LD exhibited decreased roughness following PPF, PS, and US treatments (p &lt; 0.05). In ZIR, only the BJ protocol increased roughness (p = 0.001). In conclusion, dental prophylaxis protocols do not significantly affect the mechanical strength of RC, LD, and ZIR materials, thus allowing any protocol to be used for these materials. However, for LEU ceramics, the BJ protocol should be avoided due to its effect of reducing fatigue strength and damaging the surface.

Optimizing concrete strength through the incorporation of steel nails: a comprehensive engineering analysis

The primary materials utilized in contemporary buildings are concrete and reinforced concrete. Researchers applied many methods to improve their quality and reduce costs by adding additives. The primary focus of this investigation is the compressive strength of concrete. After adding varying amounts of steel nails to the concrete mixture, the ensuing changes in compressive strength are subjected to a comprehensive analysis. Mix design was conducted, and concrete cylinders having a diameter of 4” and height of 8” were produced with varying percentages of steel nails: 1%, 2%, 3%, 4%, and 5% of the cement weight. The mixture was prepared, maintaining a constant water-to-cement ratio of 0.5. The compressive strength of the concrete is measured at 3, 7, 14, and 28 days after the mixing process. It was determined that steel nail incorporation increased compressive strength. With a 5% mix, the highest strength measured is 4775 pounds per square inch, much higher than the normal strength required for most construction projects. Furthermore, using steel nails led to a cost reduction in concrete of up to 0.5%, alongside a strength enhancement of up to 24% compared to conventional concrete.