Larger Mean Research Articles

QUANTIFICATION OF THE ACCURACY OF IN VIVO TIBIOFEMORAL KINEMATICS CALCULATED USING MAGNETIC RESONANCE IMAGING AND BIPLANE VIDEO X-RAY

AbstractObjectivesInvestigate Magnetic Resonance Imaging (MRI) as an alternative to Computerised Tomography (CT) when calculating kinematics using Biplane Video X-ray (BVX) by quantifying the accuracy of a combined MRI-BVX methodology by comparing with results from a gold-standard bead-based method.MethodsWritten informed consent was given by one participant who had four tantalum beads implanted into their distal femur and proximal tibia from a previous study. Three-dimensional (3D) models of the femur and tibia were segmented (Simpleware Scan IP, Synopsis) from an MRI scan (Magnetom 3T Prisma, Siemens). Anatomical Coordinate Systems (ACS) were applied to the bone models using automated algorithms1. The beads were segmented from a previous CT and co-registered with the MRI bone models to calculate their positions. BVX (60 FPS, 1.25 ms pulse width) was recorded whilst the participant performed a lunge. The beads were tracked, and the ACS position of the femur and tibia were calculated at each frame (DSX Suite, C-Motion Inc.). The beads were digitally removed from the X-rays (MATLAB, MathWorks) allowing for blinded image-registration of the MRI models to the radiographs. The mean difference and standard deviation (STD) between bead-generated and image-registered bone poses were calculated for all degrees of freedom (DOF) for both bones. Using the principles defined by Grood and Suntay2, 6 DOF kinematics of the tibiofemoral joint were calculated (MATLAB, MathWorks). The mean difference and STD between these two sets of kinematics were calculated.ResultsThe absolute mean femur and tibia ACS position differences (Table 1) between the bead and image-registered poses were found to be within 0.75mm for XYZ, with all STD within ±0.5mm. Mean rotation differences for both bones were found to be within 0.2º for XYZ (Table 1). The absolute mean tibiofemoral joint translations (Table 1) were found to be within ±0.7mm for all DOF, with the smallest absolute mean in compression-distraction. The absolute mean tibiofemoral rotations were found to be within 0.25º for all DOF (Table 1), with the smallest mean was found in abduction-adduction. The largest mean and STD were found in internal-external rotation due to the angle of the X-rays relative to the joint movement, increasing the difficulty of manual image registration in that plane.ConclusionThe combined MRI-BVX method produced bone pose and tibiofemoral kinematics accuracy similar to previous CT results3. This allows for confidence in future results, especially in clinical applications where high accuracy is needed to understand the effects of disease and the efficacy of surgical interventions. Acknowledgements: This research was supported by the Engineering and Physical Sciences Research Council (EPSRC) doctoral training grant (EP/T517951/1).Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Bias and mean squared error in Mendelian randomization with invalid instrumental variables.

Mendelian randomization (MR) is a statistical method that utilizes genetic variants as instrumental variables (IVs) to investigate causal relationships between risk factors and outcomes. Although MR has gained popularity in recent years due to its ability to analyze summary statistics from genome-wide association studies (GWAS), it requires a substantial number of single nucleotide polymorphisms (SNPs) as IVs to ensure sufficient power for detecting causal effects. Unfortunately, the complex genetic heritability of many traits can lead to the use of invalid IVs that affect both the risk factor and the outcome directly or through an unobserved confounder. This can result in biased and imprecise estimates, as reflected by a larger mean squared error (MSE). In this study, we focus on the widely used two-stage least squares (2SLS) method and derive formulas for its bias and MSE when estimating causal effects using invalid IVs. Using those formulas, we identify conditions under which the 2SLS estimate is unbiased and reveal how the independent or correlated pleiotropic effects influence the accuracy and precision of the 2SLS estimate. We validate these formulas through extensive simulation studies and demonstrate the application of those formulas in an MR study to evaluate the causal effect of the waist-to-hip ratio on various sleeping patterns. Our results can aid in designing future MR studies and serve as benchmarks for assessing more sophisticated MR methods.

Structural properties of newly 4,7-dihydroxycoumarin derivatives as potential inhibitors of XIIa, Xa, IIa factors of coagulation

Some coumarin derivatives show notable anticoagulant properties through their ability to interrupt the enzymatic function of vitamin K epoxide reductase. The current challenge lies in the development of novel derivatives that are more efficient and less harmful, specifically targeting the direct inhibition of coagulation factors. This study examined the direct inhibitory potential of two recently synthesized coumarin derivatives, 3-(1-(3-hydroxy-4-methoxyphenyl)-amino)-ethyldiene)-2,4-dioxochroman-7-yl acetate (A-3OH) and 3-(1-(4-hydroxy-3-methoxyphenyl)-amino)-ethyldiene)-2,4-dioxochroman-7-yl acetate (A-4OH), according to coagulation factors IIa, Xa, and XIIa. Accurately defining the structural properties of compounds is of great importance for a comprehensive understanding of the biological activity of pharmaceutical agents. In regard, this study aimed to analyze the structural (Potential Energy Surface (PES)), spectroscopic (FT-IR, NMR, and UV–Vis), and electronic properties (Quantum Theory of Atoms in Molecules (QTAIM)) of two newly synthesized compounds. These properties are determined using a combination of experimental and theoretical methods (B3LYP-D3BJ/6–311++G(d,p) level of theory). The investigated compounds deviate from planarity based on the results of structural properties. The results of QTAIM analysis show the presence of partially covalent hydrogen bonds and closed-shell van der Waals interactions that stabilize the examined compounds. Based on the large correlation coefficient (R) and low mean absolute error (MAE) of the spectroscopic data showed that the applied level of theory effectively replicated the experimental finding. The results from the molecular docking study suggest that both compounds demonstrate similar inhibitory effects on IIa when compared to the standard inhibitor dabigatran (DAB). The efficacy of A-3OH in inhibiting Xa is similar to that of conventional inhibitors apixaban (API), and rivaroxaban (RIV). The observed inhibitory effect of both compounds on coagulation factor XIIa was more potent than that of the conventional co-crystallized inhibitor. The results of this study add to the understanding of the structure-activity relationship of coumarin derivatives and provide possibilities for enhancing anticoagulant therapy and clinical outcomes for coagulation-related illnesses. The findings lay a foundation for further in vitro and in vivo investigations into the anticoagulant activities of the compounds, contributing to their potential pharmaceutical application.

Revisiting Maxwell-Smoluchowski theory: Low surface roughness in straight channels

The Maxwell-Smoluchowski (MS) theory of gas diffusion is revisited here in the context of gas transport in straight channels in the Knudsen regime of large mean free path. This classical theory is based on a phenomenological model of gas-surface interaction that posits that a fraction ϑ of molecular collisions with the channel surface consists of diffuse collisions, i.e., the direction of post-collision velocities is distributed according to the Knudsen Cosine Law, and a fraction 1−ϑ undergoes specular reflection. From this assumption one obtains the value D=2−ϑϑDK for the self-diffusivity constant, where DK is a reference value corresponding to ϑ=1. In this paper we show that ϑ can be expressed in terms of micro- and macro-geometric parameters for a model consisting of hard spheres colliding elastically against a rigid surface with prescribed microgeometry.Our refinement of the MS theory is based on the observation that the classical surface scattering operator associated to the microgeometry has a canonical velocity space diffusion approximation by a generalized Legendre differential operator whose spectral theory is known explicitly. More specifically, starting from an explicit description of the effective channel surface microgeometry—a concept which incorporates both the actual surface microgeometry and the molecular radius—and using this operator approximation, we show that ϑ can be resolved into easily obtained geometric parameters, ϑ=λh/C, having the following interpretation: C is a macroscopic parameter determined by the shape of the channel cross-section; h is a parameter that precisely captures the degree of roughness of the effective microgeometry, and λ is a parameter that characterizes the overall curvature of the surface microgeometry independent of h. Thus ϑ is resolved as the quotient of microscopic (λh) over macroscopic (C) signature parameters of the channel geometry. The identity ϑ=λh/C holds up to higher order terms in the roughness parameter h, so our main result better applies to well polished, or low roughness, surfaces.

A fast hybrid algorithm for the random vibration analysis of train-bridge systems under crosswinds

In this study, a fast hybrid algorithm based on surrogate and theoretical models is proposed. It solves surrogate model failure with too many inputs to the system and improves the computational efficiency in random vibration analysis of train-bridge systems under crosswinds. First, the surrogate model to rapidly predict the wheel-rail force time history and the theoretical model (finite element model) of the bridge are established. Then, a large number of samples of fluctuating wind speeds and track irregularities are generated based on the Monte Carlo method. Next, the wheel-rail force and the dynamic response of the bridge are calculated using the surrogate and theoretical models, respectively, and the coupling of the train and bridge subsystems is realized through iteration. Finally, the random vibrations of the train-bridge system under crosswinds are analyzed based on the calculation results of all samples. The results of the hybrid algorithm agree well with those of the traditional calculation method. The maximum normalized mean square error (NMSE) is only 0.0105, and the computational efficiency of the hybrid algorithm is nearly 4 times higher than that of traditional calculation methods. When the train is in the midspan of the bridge, the bridge dynamic response has a large mean and standard deviation. Under crosswinds, wheels on the windward side determine the safe running of the entire train. Under the wind speed of 15 m/s and Chinese high-speed railway track irregularities, the train operation reliability on the bridge is 98 %.

Ancient, veteran and other listed trees as nest sites for wild-living honey bee, Apis mellifera, colonies

Wild-living honey bee (Apis mellifera) colonies naturally nest in old cavity-bearing trees throughout their range, but this important nesting habitat is in global decline. Here we determine the use of ancient, veteran and other listed trees as nest sites by wild-living honey bee colonies in Britain and investigate the effect of tree size, genus and management on occupancy. Over 1,000 trees of special interest (TSIs) were surveyed in southeast England using the Ancient Tree Inventory (ATI) of the Woodland Trust, a charity that protects and promotes trees in Britain. 2% of all TSIs and 4.4% of TSIs with cavities were occupied by wild-living honey bee colonies (n = 21). Occupancy positively correlated with tree diameter, which is surprising given that the overall sample already had a large mean diameter of 1.3 m. Wild-living colonies occupied sweet chestnut (Castanea sativa) more frequently than expected (7% versus 2% overall), probably due to their large mean diameter (1.6 m) and proportion of trees with cavities (73%). Heights of occupied tree cavities (including non-ATI trees) ranged from 0 to 18.2 m with a median of 6.8 m, entrance size ranged from 2.2 to 322 cm2 with a median of 33.8 cm2 and entrance orientation was not significantly different from random.

Cell migration-inspired stochastic steering strategy of magnetic particles in vascular networks

One primary challenge of magnetic drug targeting is to achieve the efficient and accurate delivery of drug particles to the desired sites in complex physiological conditions. Though a majority of drugs are delivered through intravenous administration, until now, the kinematics and dynamics of drug particles influenced by the magnetic field, vascular topology, and blood flows are still less understood. In this work, a multi-physics dynamical model, which captures transient particle motions inside the vascular networks manipulated by the external magnetic field, is developed. Based on the model, we studied the transport efficiency of particles in the two-dimensional (2D), three-dimensional (3D) artificial, and in vivo-relevant vascular networks. It is found that particles that perform a random walk with correlated speed and persistence, recapitulating some characteristics of migratory motion of immune and metastasis cells, have the largest mean square displacements in various vascular network topologies. Next, we designed a stochastic magnetic steering strategy, using a time-varying gradient magnetic field, to manipulate particles to perform the cell migration-inspired random motions in the vasculature. The capability of the proposed steering strategy to improve the particle spreading speed and reduce the consumed magnetic energy has been demonstrated using our multi-physics numerical model. Furthermore, the influence of heterogeneous flows in the vascular networks on the particle steering efficiency was investigated. Overall, the numerical model and the proposed stochastic magnetic steering strategy can be used to assist the development of drug delivery systems for precise medicine research.

Valve Hemodynamics by Valve Size and 1-Year Survival Following Implantation of the Portico Valve in the Multicenter CONFIDENCE Registry

BackgroundThe CONtrolled delivery For ImproveD outcomEs with cliNiCal Evidence registry was initiated to characterize the clinical safety and device performance from experienced transcatheter aortic valve implantation (TAVI) centers in Europe and Australia that use the Portico valve to treat patients with severe aortic stenosis. We herein report for the first time the valve performance at 30-day across all implanted valve sizes and the 1-year survival from this registry. MethodsThis was a prospective, multicenter, single-arm observational clinical investigation of patients clinically indicated for implantation of a Portico valve in experienced TAVI centers. Patients were treated with a commercially available valve (size 23, 25, 27, or 29 mm) using either the first-generation delivery system (DS) (n = 501) or the second-generation (FlexNav) DS (n = 500). Adverse events were adjudicated by an independent clinical events committee according to Valve Academic Research Consortium-2 criteria. Echocardiographic outcomes were assessed at 30 days by an independent core laboratory, and a survival check was performed at 1 year. ResultsWe enrolled 1001 patients (82.0 years, 62.5% female, 63.7% New York Heart Association functional class III/IV at baseline) from 27 clinical sites in 8 countries across Europe and one site in Australia. Implantation of a single valve was successful in 97.5% of subjects. Valve hemodynamics at 30 days were substantially improved relative to baseline, with large aortic valve areas and low mean gradients across all implanted valve sizes (aortic valve areas were 1.7 ± 0.4, 1.7 ± 0.5, 1.8 ± 0.5, and 2.0 ± 0.5 cm2, and mean gradients were 7.0 ± 2.7, 7.5 ± 4.7, 7.3 ± 3.3, and 6.4 ± 3.3 mmHg for 23, 25, 27, and 29 mm valve sizes, respectively). Across all implanted valve sizes, most patients (77.1%) had no patient-prosthesis mismatch. Death from any cause within 1 year occurred in 13.7% of the patients in the first-generation DS group as compared with 11.0% in the second-generation DS group (p = 0.2). ConclusionsThe Portico valve demonstrated excellent hemodynamic performance across all valve sizes in a large cohort of subjects implanted in experienced TAVI centers. One-year survival rates were favorable when using both the first-generation and second-generation (FlexNav) DSs in this high-risk cohort. ClinicalTrials.gov IdentifierNCT03752866.

Is cardioplegia system pressure the optimal measure of coronary perfusion during antegrade cardioplegia delivery? A critical review of pressure measurements for optimal antegrade delivery.

Antegrade cardioplegia is routinely given during cardiac surgery. The delivery of antegrade cardioplegia from the cardiopulmonary bypass machine has many variables. Many perfusionists rely exclusively on cardioplegia system pressure to ensure safe antegrade delivery. Our group reviewed antegrade cardioplegia delivery in 50 patients undergoing coronary artery bypass graft. The data collected included the cardioplegia system pressure and the patient's direct aortic root pressure. The analysis of the data found weak correlation between the two pressures with a large mean difference and a wide standard deviation. The results suggest the direct measurement of aortic root pressure as guidance to antegrade cardioplegia instead of relying solely on cardioplegia system pressure.

Person-centred study on higher-order interactions between students' motivational beliefs and metacognitive self-regulation: Links with school language achievement.

Variable-centred studies assume that the links between motivation and metacognition with academic achievement are uniform across all students. However, this assumption may not hold and multiple interactions between motivational beliefs and metacognitive self-regulation may occur. To this end, the present study sought to explore these higher-order interactions and their links with school language achievement in a low-performance context. A large sample (N = 1046, 53.14% girls) of Greek secondary school students (M = 13.97, SD = .80) was drawn. Latent profile analyses were deployed to mimic higher-order interactions. Unexpectedly, the results indicated only three distinct well-defined profiles of students' motivated metacognitive self-regulation, namely exceptional motivation and metacognitive self-regulation (23.3%), adequate motivation and metacognitive self-regulation (48.2%), and minimal motivation and metacognitive self-regulation (28.5%). Incompatible profiles of motivation and metacognitive self-regulation did not emerge, contrary to previous findings suggesting negative higher-order interactions. The BCH method revealed large mean differences in school language achievement between the profiles, adjusting for covariates. Latent multinomial logistic regression indicated that gender and age predicted greater odds of membership to the minimal motivation and metacognitive self-regulation profile. Socio-economic status and spoken language at home predicted less chances of membership to the minimal profile only. Educational interventions are needed to target both motivational beliefs and metacognition to prevent underachievement.

Molecular Dynamics Mappings of the CCT/TRiC Complex-Mediated Protein Folding Cycle Using Diffracted X-ray Tracking.

The CCT/TRiC complex is a type II chaperonin that undergoes ATP-driven conformational changes during its functional cycle. Structural studies have provided valuable insights into the mechanism of this process, but real-time dynamics analyses of mammalian type II chaperonins are still scarce. We used diffracted X-ray tracking (DXT) to investigate the intramolecular dynamics of the CCT complex. We focused on three surface-exposed loop regions of the CCT1 subunit: the loop regions of the equatorial domain (E domain), the E and intermediate domain (I domain) juncture near the ATP-binding region, and the apical domain (A domain). Our results showed that the CCT1 subunit predominantly displayed rotational motion, with larger mean square displacement (MSD) values for twist (χ) angles compared with tilt (θ) angles. Nucleotide binding had a significant impact on the dynamics. In the absence of nucleotides, the region between the E and I domain juncture could act as a pivotal axis, allowing for greater motion of the E domain and A domain. In the presence of nucleotides, the nucleotides could wedge into the ATP-binding region, weakening the role of the region between the E and I domain juncture as the rotational axis and causing the CCT complex to adopt a more compact structure. This led to less expanded MSD curves for the E domain and A domain compared with nucleotide-absent conditions. This change may help to stabilize the functional conformation during substrate binding. This study is the first to use DXT to probe the real-time molecular dynamics of mammalian type II chaperonins at the millisecond level. Our findings provide new insights into the complex dynamics of chaperonins and their role in the functional folding cycle.

Opioid Consumption Following Foot and Ankle Surgery: A Systematic Review

Category: Other; Hindfoot Introduction/Purpose: The opioid epidemic in the United States has gained significant attention over the past few years. Subsequently, there have been several publications characterizing postoperative opioid consumption in patients who underwent foot and ankle surgery. Our goal was to systematically review the literature to identify trends in opioid consumption between procedures of the forefoot, midfoot, hindfoot and ankle and ultimately create finalized prescribing guidelines that treat patients’ pain adequately while limiting leftover pills. Methods: A systematic review was performed in concordance with the MOOSE guidelines. We included retrospective and prospective observational cohort studies that reported on mean opioid consumption following foot and ankle surgery, as well as unpublished data from our institution that fit the review’s parameters. We excluded studies that did not report this data or reported patients receiving alternative surgical techniques. The ROBINS-E tool was used to assess bias and the MINORS criteria was used to evaluate study quality. Results: Six studies met inclusion criteria from 395 identified articles. Reported data from 2,445 patients were analyzed for overall opioid consumption, region of surgery, and invasiveness of procedure. Five studies standardized opioids prescribed and consumed to a 5-milligram oxycodone "pill." Of the three studies reporting mean pill consumption by region of surgery, 16.1, 27.8, and 26.4 pills were consumed by forefoot, midfoot, and hindfoot patients, respectively. The largest mean and median pill consumption was observed in hindfoot patients (45.7 and 22, respectively). 4 of 5 studies found significantly higher opioid use in hindfoot and ankle patients, and 2 of 5 studies found significantly higher consumption among those undergoing bony versus soft-tissue procedures. Across all studies, patients used 45.7%-75.2% of their opioid prescriptions. Conclusion: In this systematic review, we identify literature reported mean number of recommended pills to be subscribed for each anatomical region, as prescriptions could be decreased by around half and still adequately control pain. This can be of significant aid in providing final guidelines to orthopedic surgeons to finalize prescription patterns in foot and ankle surgery based on the published literature.

A-137 Performance Evaluation of an Automatic, Rapid and Non-Westergren Based Method for Erythrocyte Sedimentation Rate Measurement

Abstract The erythrocyte sedimentation rate (ESR) is widely used for the assessment of acute or chronic inflammation, especially for rheumatoid diseases. The gold standard for determining ESR is the Westergren method, which measures the distance in millimeters that red blood cells fall in one hour. However, this method needs to be performed manually, which increases the biohazard risk to laboratory personnel, and the results are often influenced by many preanalytical and analytical factors. Several automated ESR analyzers with different methodologies are now available to provide faster results directly from whole blood anticoagulated with K3EDTA. In this study, we evaluated the performance of an automatic ESR analyzer, Alifax TEST1, and compared it with that of another automatic analyzer, Diesse Cube 30 touch, and also the Westergren method. TEST1 extrapolates the ESR values by measuring the kinetics of red cells aggregation in 20 s, while Cube 30 is a modified Westergren method that could obtain the results in 20 min. A total of 75 clinical samples were analyzed for ESR using the three methods. The hematocrit (Hct) and C-reactive protein (CRP) values were also analyzed. The Spearman correlation coefficient between TEST1 and Westergren methods was 0.90 (P < 0.0001) with a mean difference of -5.45; the correlation between Cube 30 and Westergren methods was 0.80 (P < 0.0001) with a mean difference of 10.74; the correlation between TEST1 and Cube 30 was 0.69 (P < 0.0001) with a mean difference of -15.9. The precision values (CV %) of TEST1 in low-, medium- and high-level controls were 2.71%, 1.21% and 1.05% for inter-assay, and 3.70%, 1.66% and 0.86% for intra-assay. The normal range of TEST1 was also established by analyzing ESR values of 125 healthy individuals where it is 0–15 mm/hr for men ≤50years old, 0–20 mm/hr for men > 50 years old and for women ≤50 years old, and 0–30 mm/hr for women > 50years old. The ESR values obtained from the three methods all significantly correlated with plasma CRP levels. However, the ESR values from Cube 30 and Westergren methods negatively correlated with Hct values, while that from TEST1 did not. The present study demonstrates that 1) TEST1 has a better correlation and a lower difference to the Westergren method compared to Cube 30, suggesting that TEST1, the automatic, rapid and non-Westergren based method is an effective assay for clinical practice; 2) the Westergren based methods are more easily influenced by Hct; 3) the large mean difference between TEST1 and Cube 30 highlights a need for harmonization of the ESR values obtained from different automatic analyzers, especially when it is applied to monitor the disease activity score (DAS28) in rheumatoid arthritis patients.

Harnessing a mesopelagic predator as a biological sampler reveals taxonomic and vertical resource partitioning among three poorly known deep-sea fishes

Pelagic predators are effective biological samplers of midtrophic taxa and are especially useful in deep-sea habitats where relatively mobile taxa frequently avoid observation with conventional methods. We examined specimens sampled from the stomachs of longnose lancetfish, Alepisaurus ferox, to describe the diets and foraging behaviors of three common, but poorly known deep-sea fishes: the hammerjaw (Omosudis lowii, n = 79, 0.3–92 g), juvenile common fangtooth (Anoplogaster cornuta, n = 91, 0.6–22 g), and juvenile Al. ferox (n = 138, 0.3–744 g). Diet overlap among the three species was high, with five shared prey families accounting for 63 ± 11% of the total prey mass per species. However, distinct differences in foraging strategies and prey sizes were evident. Resource partitioning was greatest between An. cornuta that specialized on small (mean = 0.13 ± 0.11 g), shallow-living hyperiid amphipods and O. lowii that specialized on large (mean = 0.97 ± 0.45 g), deep-dwelling hatchetfishes. Juvenile Al. ferox foraged on a high diversity of prey from both shallow and deep habitats. We describe the foraging ecologies of three midtrophic fish competitors and demonstrate the potential for biological samplers to improve our understanding of deep-sea food webs.

Multi-Objective Optimization of The Low-Pressure Casting of Large-Size Aluminum Alloy Wheels through a Systematic Optimization Idea.

The process parameters in the low-pressure casting of large-size aluminum alloy wheels are systematically optimized in this work using numerical casting simulation, response surface methodology (RSM), and genetic algorithm (NSGA-II). A nonlinear input-output relationship was established based on the Box-Behnken experimental design (BBD) for the crucial casting parameters (pouring temperature, mold temperature, holding pressure, holding time), and response indicators (defect volume fraction, spokes large plane mean secondary dendrite spacing (SDAS)), and a mathematical model was developed by regression analysis. The Isight 2017 Design Gateway and NSGA-II algorithm were used to increase the population and look for the best overall solution for the casting parameters. The significance and predictive power of the model were assessed using ANOVA. Casting numerical simulation was used to confirm the best option. To accomplish systematic optimization in its low-pressure casting process, the mold cooling process parameters were adjusted following the local solidification rate. The results showed that the mathematical model was reliable. The optimal solutions were a pouring temperature of 703 °C, mold temperature of 409 °C, holding pressure of 1086 mb, and holding time of 249 s. The mold cooling process was further optimized, and the sequence solidification of the optimal solution was realized under the optimized cooling process. Finally, the wheel hub was manufactured on a trial basis. The X-ray detection, mechanical property analysis, and metallographic observation showed that the wheel hub had no X-ray defects and its mechanical properties were well strengthened. The effectiveness of the system optimization process scheme was verified.

A new path integration method for the stochastic system under Poisson white noise excitation based on a probability mapping

In this paper, a new path integration method is proposed for stochastic dynamical systems excited by Poisson white noise. An efficient one-step transition probability density function (TPDF) matrix is constructed based on a decoupling probability mapping. The new method can handle the case of multiple impulses occurring in a one-step transition time interval and considers the randomness of the impulse instant, which compensates for a drawback of previous path integration methods. The probability mapping realizes the decoupling of randomness and the one-step TPDF matrix, which can be extended to general stochastic systems satisfying the Markov property. The stochastic responses of two dynamical systems excited by Poisson white noises for different mean arrival rates are obtained by using the new path integration method, and MC simulations prove that the new method is very effective, and it maintains good accuracy even for large mean arrival rates.

Water-soluble biopolymers from heat-treated and high pressure homogenized vegetable purées: investigating their emulsion forming and stabilizing capacities.

The emulsion forming and stabilizing capacities of water-soluble biopolymers originating from the aqueous (serum) phase of heat-treated and high pressure homogenized purées were investigated. The serum biopolymers were characterized and then utilized as emulsifier/stabilizer in simple oil-in-water emulsions. The resulting emulsions were stored at 4°C and monitored for 2 weeks. Results revealed that carrot and tomato sera contained higher amounts of pectin and lower protein compared to broccoli. The serum pectic biopolymers exhibited distinct molecular structures, depending on the vegetable origin. Given these natural biopolymer composition and characteristics, emulsions with small droplet sizes were observed at pH 3.5. However, emulsions at pH 6.0 showed large mean droplet sizes, except for the emulsion formulated with carrot serum. Regardless of the pH, emulsions containing carrot serum biopolymers exhibited high capacity to form fine emulsions that were stable during the 2-week storage period at low temperature. This study clearly shows the capacity of natural water-soluble biopolymers isolated from the serum phase of vegetable purées to form fine emulsion droplets and maintain its stability during storage, especially in the case of carrot serum biopolymers.

High-Frequency Pulsed Coaxial Injectors for High-Speed Flow Mixing and Control

Efficient and controlled mixing of fuel with fast-moving air is a challenging physical problem relevant to hypersonic systems. Although mixing happens at the molecular level through diffusion, the macroscopic phenomenon such as entrainment and vorticity dynamics resulting from the shear layer instabilities of the mixing fluids play a significant role in the overall efficiency of the process. With a focus on improving mixing at extreme flow conditions, this paper presents a fundamental study of a novel, high-speed, pulsed coflow system integrated with ultrahigh-frequency actuators (11–20 kHz). This injection system consists of a supersonic actuation air jet at the inner core that provides large mean and fluctuating velocity profiles in the shear layers of a fluid stream injected surrounding the core through an annular nozzle, with pulsing occurring at a designated frequency. The high-frequency streamwise vortices and shockwaves tailored to the mean flow significantly enhanced supersonic flow mixing between the fluids compared to a steady coaxial configuration operating at the same input pressure. Experiments also indicate a strong connection between the frequency and unsteady amplitude of the actuation jet to the supersonic flow mixing phenomenon. This paper reports the design details of the injector assembly and flow mixing characteristics captured using phase-locked microschlieren and planar laser-induced fluorescence techniques.

An equivalent strain energy density model for fatigue life prediction under large compressive mean stress

In this work, a modified Smith-Watson-Topper (SWT) model is proposed for the consideration of large compressive and tensile mean stresses. Firstly, the maximum normal stress in the original SWT model is replaced with equivalent stress amplitude, and the SWT parameter is thereafter interpreted as equivalent strain energy density (ESED). The newly proposed ESED model gives improved prediction results in fatigue life, especially under conditions with large compressive mean stress. Secondly, the applications of different mean stress correction (MSC) models are investigated with their limitations carefully examined. In order to improve the ESED model with higher accuracy, a new exponential MSC model is proposed. Moreover, an additional parameter concerning the dependency of material on mean stress is proposed. With the exponential MSC model incorporated, the ESED model is validated with experimental data from several different materials, and shows obviously improved prediction results compared with SWT model and some recent life prediction models.

Stone Heterogeneity Index as a New Parameter for Prediction of Shockwave Lithotripsy Outcomes

Background Renal stones are a major public health concern with continuously increasing prevalence. Extracorporeal shock wave lithotripsy (ESWL) which was introduced more than three decades ago as an authentic modality for the treatment of urinary stone disease is considered first choice of treatment for nearly all kind of urinary tract calculi. The outcome of ESWL for renal and ureteral stones depends on many factors, including stone size, Hounsfield Unit (HU), Skin Stone Distance (SSD) and Body Mass Index (BMI). Objective To introduce the concept of Stone Heterogeneity Index (SHI) as a single factor or in combination with other factors that predict the outcome of extracorporeal shock wave lithotripsy for adult patients with renal or ureteral stones. Methods This is a prospective study conducted on 60 Patients with renal and ureteral stones planned to have ESWL sessions attending urology outpatient clinic in Ain shams university and Misr University for Science and Technology hospitals. Results The radiologic heterogeneity of a urinary stone or SHI was independently associated with SWL success in patients with renal and ureteral calculi. SHI in the success group was 246.49 ± 82.13 while in the failure group was 159.20 ± 47.59 with Cutoff point < 183 predicting failure of ESWL outcome. SHI between success and failure groups was statistically significant being higher in success group. (p = 0.000). Conclusion SHI will play a promising role when determining a treatment modality in patients with a urinary stone, and especially when selecting the proper SWL candidates from the patients with a stone of large size or high Mean Stone Density (MSD).