Construction Of Curves Research Articles

Dynamic mechanical analysis of epoxy composites: Master curve construction and prony series fitting to investigate filler shape effects on viscoelastic properties

Dynamic mechanical analysis of epoxy composites: Master curve construction and prony series fitting to investigate filler shape effects on viscoelastic properties

A novel imaging-based method to estimate left ventricular filling pressure

Abstract Background There is a clinical need in heart failure diagnostics to have a non-invasive measure of left ventricular (LV) filling pressure. Echocardiographic parameters may be used to differentiate between normal and elevated left ventricular (LV) filling pressure, but do not provide a quantitative estimate of the filling pressure. Purpose To establish a non-invasive method for estimating LV filling pressure and construction of the LV diastolic pressure curve. Methods Retrospective study in 100 patients with suspected coronary artery disease. Ground truth filling pressure (i.e. LV pre-atrial contraction pressure, which is shown to approximate mean left atrial pressure) was measured by LV micromanometer-tipped catheters. Non-invasive filling pressure was estimated as the sum of minimum LV pressure (minPLV) and the maximum early-diastolic atrio-ventricular pressure difference (∆PA-V), as shown in Figure 1. MinPLV was estimated by a regression model trained in 81 patients, which included an estimate of the time constant of τ (Figure 1) and echocardiographic and demographic parameters. ∆PA-V was computed by a simplified Navier-Stokes momentum conservation equation. Accuracy of filling pressure estimate was evaluated in a test cohort of 19 patients. Results The strongest predictor of minPLV was τ (R=0.71) followed by LA reservoir strain (R=0.65), LV systolic pressure (R=0.23) and body mass index (R=0.37), all of them independent predictors. There was good agreement between estimated and measured τ (Bias -0.0069s and limits of agreement <0.0195s). When combining estimated τ and the three other predictors in a regression model, there was good agreement between estimated and measured minPLV: Bias -0.5 mmHg, limits of agreement <1.9 mmHg (±2SD). Estimated LV filling pressure also showed good agreement with measured values: Bias 0.0 mmHg, limits of agreement <3.1 mmHg, shown in Figure 2. The diastolic pressure curve was estimated with good accuracy (diastolic meanPLV had bias and limits of agreement were respectively 0.2 and <3.2mmHg). Conclusions The proposed non-invasive method estimated LV filling pressure with good accuracy in a population with coronary artery disease. The method also allowed approximation of the LV diastolic pressure curve. The method needs validation in larger populations and in other phenotypes. Method to calculate LV filling pressure LV filling pressure (pre-A) agreement

Between-day variability of soleus H reflex recruitment curve parameters: how many stimulations are required to maximise the reproducibility of the measurements?

Purpose The H reflex recruitment curve represents the gold standard for quantifying changes in spinal circuitries. However, there is no agreement on how many stimulations should be applied for each parameter. Thus, we explored the impact of varying the number of stimulations (3, 6, 9, 12 and 15 stimuli per intensity) on between-day reliability of soleus H reflex. Materials and Methods Twenty healthy participants (11 males, 9 females; age: 22.4 ± 2.3 years) visited the laboratory on two days for H-recruitment curves construction, using a 3 s inter-stimuli interval. To explore whether H reflex parameters differed between days, without varying the number of stimulations, paired-sample t tests were performed. Relative and absolute reliability were calculated using the intraclass correlation coefficients (ICCs) and the coefficients of variation (CVs), respectively. Results Mmax, Hmax/Mmax, H slope, Hthresh, current at 50% of Hmax and current at Hmax were not significantly different between days (all p > 0.05). ICCs of Mmax, Hmax/Mmax and Hthresh were all good (0.79–0.89). H slope ICCs were moderate (0.56–0.73) between 3 and 12, but good (0.75) with 15 stimulations. Current at Hmax ICCs were moderate (0.55–0.0.73) with all stimulations, except with 9 (good: 0.76). CVs of the current at Hmax were all moderate (between 5-to-10%). Hthresh CV was poor (>10%) with three, but moderate for other stimulations. Mmax, Hmax/Mmax and H slope CVs were generally poor. Conclusions 9 stimulations are required to ensure higher between-day reliability of H reflex parameters, except for H slope that requires 15 stimulations.

Bezier Curves and Surfaces with the Generalized α-Bernstein Operator

In the field of Computer-Aided Geometric Design (CAGD), a proper model can be achieved depending on certain characteristics of the predefined blending basis functions. The presence of these characteristics ensures the geometric properties necessary for a decent design. The objective of this study, therefore, is to examine the generalized α-Bernstein operator in the context of its potential classification as a novel blending type basis for the construction of Bézier-like curves and surfaces. First, a recursive definition of this basis is provided, along with its unique representation in terms of that for the classical Bernstein operator. Next, following these representations, the characteristics of the basis are discussed, and one shape parameter for α-Bezier curves is defined. In addition, by utilizing the recursive definition of the basis, a de Casteljau-like algorithm is provided such that a subdivision schema can be applied to the construction of the new α-Bezier curves. The parametric continuity constraints for C0, C1, and C2 are also established to join two α-Bezier curves. Finally, a set of cross-sectional engineering surfaces is designed to indicate that the generalized α-Bernstein operator, as a basis, is efficient and easy to implement for forming shape-adjustable designs.

Combining extraction and cultivation methods for soil seed bank analysis increases number of captured species and their similarity to above-ground vegetation.

Analysis of aboveground vegetation and soil seed bank is an important source of data on the state and dynamics of vegetation. It is especially important in landscapes exposed to disturbances, which have lost their functions. For our research, a post-mining area in the region of the Upper Silesian Black Coal Basin was selected, whose relief and ecosystems are strongly disturbed by underground mining and are currently also affected by ongoing climate change. Data collection for our research took place in the territory of two waterlogged subsidence basins in the Karvina region, Czech Republic. We evaluated 30 phytosociological releves using techniques of Zurich - Montpellier school and 540 soil cores using cultivation and extraction method. In the above-ground vegetation, 115 plant species were identified. By cultivating soil samples, we determined 60 species from 1,487 seedlings, by extraction method 66 species from 5,999 seeds. A statistically significant effect of the presence of the tree layer on the number of species obtained by the extraction method was demonstrated. There is also a statistically significant difference between the selected analysis methods in terms of the length of the captured seeds and their seed mass. The construction of a rarefaction curve demonstrated that the use of cultivation and extraction methods leads to a greater capture of soil seed bank species. The similarity between the species composition of aboveground vegetation and the soil seed bank correspond to similarities observed in other studies from degraded habitats. Very low similarity between the species of the soil seed bank from cultivation and extraction method is probably caused by the highly variable distribution of seeds in the soil in time and space.

Review and characterization of the 2014 Orkney damage datasets for damage pattern mapping and fragility curve construction

The 2014 Orkney earthquake caused significant damage to unreinforced masonry buildings in the surrounding townships. After the earthquake, field surveys were conducted to assess the extent of damage in the affected areas. This study reviews data collected from the 2014 Orkney earthquake to investigate damage patterns, evaluate building safety for occupancy, and support fragility curve construction. Damage was quantified based on the European Macroseismic Scale (EMS-98) to assess building safety and conduct regression analysis. The results indicate that the collected data is suitable for investigating damage patterns and determining building safety for occupancy. However, it is not suitable for constructing fragility curves. Empirical fragility curves are typically developed using logistic regression, but this study found the data unsuitable for regression analysis due to sampling errors and limited data quantity. This study recommends the use of first-order approximation methods to supplement the dataset, reducing sampling errors and increasing data quantity.

Head Circumference for Growth Curves and Percentiles for 0-2-Year-Old Children in Ankara: Comparison with GAMLSS and Quantile Regression Methods.

Objective: Growth curves are important tools for assessing the growth and development of children in the target population by age. Measuring head circumference (HC) in infants is an important tool in monitoring infant health and brain development. The aims of this study are to construct current 0-2-year-old HC growth curves and percentiles and compare the methods used in the construction of growth curves for HC measurements by gender. Materials and Methods: The study is a retrospective research that includes the HC measurements of a total of 2832 (n = 1438 girls, n = 1394 boys) children examined between 2018 and 2021 in Başkent University hospital, Ankara. Lambda-Mu-Sigma, LMSP, and LMST methods based on Box-Cox Cole and Green (BCCG), Box-Cox power exponential (BCPE), and Box-Cox t (BCT) distributions respectively, and quantile regression (QR) method were used to construct the fitted growth curves. Model performances were evaluated using the generalized Akaike information criterion. The analyses were conducted using R 4.1.2 version. Results: According to the LMS and QR methods, percentile values of HC measurements by gender were calculated and the results were compared. Smoothed HC growth curves were constructed and compared for both methods by gender. The present study, Neyzi et al study, and World Health Organization (WHO) standards were compared for the third, 50th and 97th percentiles of HC. Conclusion: This study showed that the third-97th HC percentiles calculated by LMS and QR methods are very close to each other. Additionally, this study showed that the HC percentiles of Turkish children were slightly different compared to WHO standards.

Construction of Free Curves by Adding Osculating Conics to a Given Cubic Curve

Abstract In the present article we construct new families of free and nearly free curves starting from a plane cubic curve $C$ and adding some of its hyperosculating conics. We present results that involve nodal cubic curves and the Fermat cubic. In addition, we provide new insight into the geometry of the $27$ hyperosculating conics of the Fermat cubic curve using well-chosen group actions.

Direct Determination of Flavanone Isomers in Citrus Juice by Paper Spray Tandem Mass Spectrometry.

A novel and efficient analytical protocol based on paper spray tandem mass spectrometry was developed for the determination of isomeric O-glycoside flavanones in citrus juices and beverages. This approach significantly reduces sample preparation time and solvent consumption compared to traditional chromatographic techniques. By exploiting the unique fragmentation patterns of these compounds, accurate quantification of both diglycosides and their individual isomers (neohesperidoside and rutinose derivatives) was achieved. The method demonstrated excellent analytical performance, with high accuracy, selectivity, and reproducibility. The impact of matrix effects was mitigated through the construction of ratio calibration curves, ensuring reliable quantification in complex matrices. Finally, a simple DPPH experiment to assay the antioxidant activity of each single positional isomer was performed, indicating the superior ability of neohesperidose conjugates. This simplified method offers a valuable tool for quality control, authenticity assessment and the study of health benefits associated with citrus consumption.

The underpinning of the evaluation of aerobic endurance based on methods established in the late 20th century: A systematic review

<p style="text-align: justify;">This systematic review aims to analyze the validity (invasive and noninvasive protocols) of aerobic endurance evaluation methods established in the late 20th century and their practical application in creating training series in different sports events. The PRISMA system was used for systematic review. It was identified that high number of studies support the concept of the evaluation of aerobic endurance, i.e., aerobic threshold (AnT), in terms of its significance for the determination of training series and training intensity aimed at aerobic endurance improvement. During the protocol of testing and construction of the lactate curve (La – work capacity), the method based on sampling and measurement of lactate concentration in blood is given priority as a more valid instrument for AnT determination than the method based on ventilatory parameters and heart frequency. Authors note that the parameters based on which AnT is determined are expressed in different units of measure (m/min, km/h, ml/kg/min) so that AnT, as such, does not only represent the measure of aerobic endurance but also the measure of maximal oxygen consumption (VO2max) and mechanical efficiency. The results of the study indicate that terms related to AnT should be removed from official use. More precisely, researchers and coaches focus on a method related to the interpretation of the lactate curve (at a certain %VO2max) to determine whether there has been an improvement (or not) in aerobic endurance based on its displacement (to the right or to the left).</p>

Sn-Position-Resolved Quantification of Aminophospholipids by Isotopic N,N-Dimethyl Leucine Labeling and High-Resolution Ion Mobility Mass Spectrometry.

Aminophospholipids (APLs), composed of phosphatidylethanolamines (PEs) and phosphatidylserines (PSs), are vital components of mammalian cell membranes and lipoproteins, participating in both homeostasis and cellular signaling. Their structural changes, including the permutation of fatty acid connectivity (sn-positions), due to dysfunctional metabolic processes have been linked to many diseases. However, the accurate quantification of APLs with unambiguous fatty acyl assignment through routine label-free LC-MS/MS lipidomic analysis remains a major challenge. In this study, we explore the functionalization of the free primary amine groups of APLs using amine-reactive isotopic N,N-dimethyl leucine (iDiLeu) and employ high-resolution ion mobility MS (IM-MS) to develop a novel method for sensitive discernment and accurate quantification of APL sn-isomers. With high-resolution demultiplexing (HRdm) providing IM resolving power >200, labeled sn-isomeric pairs of APLs (ΔCCS ≈ 1%) demonstrate excellent, near baseline separation. In addition to greatly enhanced sensitivity, 5-plex iDiLeu labeling enables the construction of an internal 4-point calibration curve and therefore absolute quantification of APL sn-isomers in a single run. This strategy enabled precise annotation and quantification of 239 APLs including 60 pairs of sn-isomers in the mouse cortex. Additionally, we were able to find ratio changes in multiple APL sn-isomer pairs between wild type and APP/PS1 Alzheimer's disease (AD) model mice at different ages, indicating their strong correlation to AD progression. This strategy could provide universal utility in unraveling the alteration of APL sn-isomers, which have long been considered as the "dark matter" of traditional lipidomic analyses, leading to more precise elucidation of molecular mechanisms of various diseases.

Treatment of elderly patients with acute myeloid leukemia: personal experience

Background. Acute myeloid leukemia (AML) is an aggressive malignancy of the hematopoietic system. Most patients with newly diagnosed AML are 65 years of age or older. Treatment of this cohort of patients is difficult due to the comorbidity of elderly patients and the genetic characteristics of hemoblastosis, which prevents the achievement of significant progress in treatment, in contrast to younger patients with AML. As domestic and foreign studies have shown, age is an independent universal prognosis factor for AML. In the era of targeted drugs, successful treatment of AML is becoming possible.Aim. To assess overall survival in elderly patients with AML, tolerability and effectiveness of various treatment regimens in patients with AML ≥65 years.Materials and methods. This paper presents our own experience in the treatment of elderly patients with AML in the hematology departments of the City Clinical Hospital No. 52. The study included patients over 65 years of age with AML from April 2022 to September 2023. A total of 40 patients were analyzed. To determine the risk factors for death, univariate and multivariate regression analyzes were performed using the logistic regression method. Variables that showed statistical significance on univariate analysis were included in the multivariate analysis. An analysis of 12‑month overall survival was also carried out using the Kaplan–Meier method with the construction of survival curves and calculation of median survival. A comparative analysis of two groups of patients treated with the AZA + EN and LdaraC regimens was carried out.Results. 63 % (n = 25) are men, 37 % (n = 15) are women. The median age was 75 years; all patients had complicated premorbid background. 53 % (n = 21) of patients were in the age range from 65 to 69 years, 47 % (n = 19) were over 70. Antitumor treatment was received by 88 % (n = 35) of patients. The remaining 5 underwent: best accompanying (n = 2), cytoreductive (early death at this stage) (n = 3) therapy. Complete remission after two cycles of therapy was achieved in 46 % (n = 16) of patients, and in 29 % (n = 10) it was maintained at the time of analysis. Early relapse occurred in 14 % (n = 5). Early mortality was recorded in 9 % (n = 3). Death was reported in 40 % (n = 16) of patients. 20 % (n = 7) of patients were refractory to first-line therapy, of which 36 % (n = 5) were treated with low doses of cytarabine (LdaraC), the rest to a combination of azacitidine (AZA) with venetoclax (EN). The number of relapses among patients on AZA + EN and LdaraC therapy was comparable.Conclusion. AZA + EN is the first-line treatment of choice in older patients with AML. The possibility of conducting this course in an outpatient setting makes it most convenient for both hematologists and patients. An important aspect in the treatment of AML in elderly patients is improving and maintaining quality of life.

Construction of The Load-Transfer Curves for Piles in Sand on The Basis of The Standard Penetration Test

Construction of The Load-Transfer Curves for Piles in Sand on The Basis of The Standard Penetration Test

Antimicrobial and Antifungal Action of Biogenic Silver Nanoparticles in Combination with Antibiotics and Fungicides Against Opportunistic Bacteria and Yeast.

The development of multidrug resistance by pathogenic bacteria and yeast is a significant medical problem that needs to be addressed. One possible answer could be the combined use of antibiotics and silver nanoparticles, which have different mechanisms of antimicrobial action. In the same way, these nanoparticles can be combined with antifungal agents. Biogenic silver nanoparticles synthesized using environmentally friendly biosynthesis technology using extracts of biologically active plants are an effective nanomaterial that needs to be comprehensively investigated for implementation into medical practice. In this study, the synergistic effects arising from their combined use with antibiotics and fungicides against various bacteria and yeasts were studied. The following methods were used: disco-diffusion analysis and construction of plankton culture growth curves. The synergistic effect of silver nanoparticles and antibiotics (fungicides) has been determined. Effective concentrations of substances were established, recommendations for the studied pathogenic species were presented, and the effect of destruction of the bacterial membrane was illustrated. The most significant synergistic effect was manifested in pathogenic candida and brewer's yeast.

Artificial Neural Network-Based Non-Linear Modeling and Simulation of CaO-SiO2-Al2O3-MgO Blast Furnace Slag Viscosity

Blast furnace slags are formed by CaO-SiO2-Al2O3-MgO systems and have several physical characteristics, one of which is viscosity. Viscosity is an important variable for the operation and blast furnace performance. This work aimed to model viscosity through linear and non-linear models in order to obtain a model with precision and accuracy. The best model constructed was a non-linear model by artificial neural networks that presented 23 nodes in the first hidden layer and 24 nodes in the second hidden layer with 6 input variables and 1 output variable named ANN 23-24. ANN 23-24 obtained better statistical evaluations in relation to 11 different literature equations for predicting viscosity in CaO-SiO2-Al2O3-MgO systems. ANN 23-24 was also subjected to numerical simulations in order to demonstrate the validation of the non-linear model and presented applications such as viscosity prediction, calculation of the inflection point in the viscosity curve by temperature, the construction of ternary diagrams with viscosity data, and the construction of iso-viscosity curves.

Physicochemical Rationale of Matrix Effects Involved in the Response of Hydrogel-Embedded Luminescent Metal Biosensors.

There is currently a critical need for understanding how the response and activity of whole-cell bacterial reporters positioned in a complex biological or environmental matrix are impacted by the physicochemical properties of their micro-environment. Accordingly, a comprehensive analysis of the bioluminescence response of Cd(II)-inducible PzntA-luxCDABE Escherichia coli biosensors embedded in silica-based hydrogels is reported to decipher how metal bioavailability, cell photoactivity and ensuing light bioproduction are impacted by the hydrogel environment and the associated matrix effects. The analysis includes the account of (i) Cd speciation and accumulation in the host hydrogels, in connection with their reactivity and electrostatic properties, and (ii) the reduced bioavailability of resources for the biosensors confined (deep) inside the hydrogels. The measurements of the bioluminescence response of the Cd(II) inducible-lux biosensors in both hydrogels and free-floating cell suspensions are completed by those of the constitutive rrnB P1-luxCDABE E. coli so as to probe cell metabolic activity in these two situations. The approach contributes to unraveling the connections between the electrostatic hydrogel charge, the nutrient/metal bioavailabilities and the resulting Cd-triggered bioluminescence output. Biosensors are hosted in hydrogels with thickness varying between 0 mm (the free-floating cell situation) and 1.6 mm, and are exposed to total Cd concentrations from 0 to 400 nM. The partitioning of bioavailable metals at the hydrogel/solution interface following intertwined metal speciation, diffusion and Boltzmann electrostatic accumulation is addressed by stripping chronopotentiometry. In turn, we detail how the bioluminescence maxima generated by the Cd-responsive cells under all tested Cd concentration and hydrogel thickness conditions collapse remarkably well on a single plot featuring the dependence of bioluminescence on free Cd concentration at the individual cell level. Overall, the construction of this master curve integrates the contributions of key and often overlooked processes that govern the bioavailability properties of metals in 3D matrices. Accordingly, the work opens perspectives for quantitative and mechanistic monitoring of metals by biosensors in environmental systems like biofilms or sediments.

Construction and Comparation of Critical Nitrogen Concentration Dilution Curves for Spring and Autumn Potato in China

Nitrogen is one of the essential nutrients for the growth and development of potato plants. The precise application of nitrogen can improve the yield and quality of potatoes and enhance their resistance to diseases. The changes in the critical N dilution curves of the shoot, root, and whole plants of potato were analyzed according to different N levels. The difference in the critical nitrogen concentration dilution curve of potatoes in spring and autumn was discussed. It is of great significance for the precise management of nitrogen fertilizer in spring and autumn potatoes. In this experiment, four field experiments were conducted using two potato cultivars (Zheshu956 and Yongma1) with four varying N application levels (N0–N3). Two identical varieties were planted at the same location in the spring and autumn and there was no significant difference in the selection of the same varieties between the two seasons. The dry matter and nitrogen concentration of roots, stems, leaves, and tubers were measured after transplantation at different stages. The results showed that the critical nitrogen concentration models for the shoot, root, and whole plant of potatoes were constructed as follows: spring potato shoot, N = 4.8712 W−0.203, root, Nc = 1.8477 W−0.157, and whole plant, Nc = 4.1679 W−0.293; autumn potato shoot, Nc = 3.8653 W−0.204, root, Nc = 2.1529 W−0.158; and whole plant, Nc = 3.2569 W−0.304. The critical nitrogen curves for the aboveground part and the whole plant of spring potato were significantly higher than that of autumn potato. Under N2 (160 kg ha−1) treatment, both spring and autumn potatoes reach their maximum yield. The critical nitrogen concentration dilution curve based on the whole plant was determined to be more appropriate for potatoes. The critical nitrogen concentration curves of potatoes in spring and autumn were significantly different for the aboveground part and the whole plant, but there was no significant difference for the underground part. The separately constructed nitrogen nutrition indices can be used to diagnose the nitrogen requirements of spring and autumn potatoes.

Novel clinical method: left ventricular diastolic pressure curve by echocardiography

Abstract Background A non-invasive clinical method for construction of the systolic part of the left ventricular (LV) pressure curve was recently introduced. There is, however, no clinical method available to construct the LV diastolic pressure curve. Purpose The aim of this study was construction of patient-specific LV diastolic pressure curves from echocardiographic data and have initial validation against simultaneously acquired pressure curves by high-fidelity LV pressure catheters (micromanometers). Methods The study included 108 patients referred for diagnostic left heart catheterization due to suspected coronary artery disease. 81 patients were used as a training cohort. The construction of a diastolic pressure curve is based on a reference unitless pressure trace and seven key pressure-time diastolic events estimated in each patient. The reference diastolic pressure trace was generated from a group of 8 patients with LV pressures recorded by micromanometer. Each individual pressure trace from the reference cohort was first annotated with the occurrence of the key diastolic events: mitral valve (MV) opening, minimum LV pressure, peak of early-diastolic mitral flow velocity (E) and start and peak of atrial contraction-induced velocity (A), and MV closure. Then the temporal intervals between these events were normalized before calculating an averaged pressure curve (Figure 1, panels A-C). A patient-specific LV diastolic pressure curve was constructed by adjusting the standard curve according to estimated LV pressure at the key diastolic events (shown in Figure 1D). The estimation of the pressure-time instants is based on the LV volume temporal transient, used to estimate filling flow rate (Q=dV/dt) and flow acceleration and deceleration (dQ/dt=d2V/dt2), as well as a set of biomarkers including left atrial reservoir strain, peak systolic LV pressure, and body mass index. LV volume temporal traces were generated by combining global 2D volumes with global longitudinal strain. The ability to generate patient-specific diastolic LV pressure curves was validated in a second cohort of 7 patients studied with micromanometer-tipped catheters. Echocardiography and LV pressure were recorded from the same series of beats and recordings were done during breath-hold at end-expiration. The agreement was accessed qualitatively and considering the mean diastolic LV pressure. Results There was good agreement between measured and estimated LV diastolic pressure curves, qualitatively and quantitatively, via mean diastolic PLV: Bias 0.2 mmHg, limits of agreement <3.2 mmHg (Figure 1D-F). Conclusions The results suggest that the LV diastolic pressure curve can be estimated by echocardiography. The method needs validation in larger populations.Non-invasive diastolic LV pressure curve

Evaluation of myocardial work indexes in patients with cardiac sarcoidosis

Abstract Background Cardiac involvement is associated with worse prognosis and mortality in sarcoidosis. Diagnosis often requires expensive and less available tests. Purpose The aim of this study is to evaluate whether non-invasive measurement of myocardial work by transthoracic echocardiogram has incremental value in the diagnosis of cardiac involvement compared to left ventricular (LV) global longitudinal strain (GLS). Methods This is a cross-sectional, non-blinded, single-center pilot study. Patients of both genders > 18 years old, with confirmed diagnosis of cardiac sarcoidosis according to the Heart Rhythm Society criteria, and controls consisting of individuals diagnosed with systemic sarcoidosis without cardiac involvement, were included. Patients with obesity grade 2 or higher , moderate or severe primary heart valve disease, myocardial diseases of other etiologies, established coronary artery disease, and inadequate acoustic window were excluded. All patients underwent transthoracic echocardiography and non-invasive blood pressure measurement, followed by subsequent analysis involving the construction of a pression-strain curve. The following LV indexes were calculated: GLS, global work index, global constructive work, global wasted work, and global work efficiency. ROC curves were calculated for all variables using the EasyROC online tool (v 1.3.1), and these were later compared to GLS. Confidence intervals were established by the DeLong method, and curves were compared by the Bonferroni method. A two-tailed p value of 0.05 was considered significant. Results Twenty patients with cardiac involvement and twenty patients without cardiac involvement were evaluated. The results of the variables are presented in table 1. Conclusions With exception of wasted work, all other LV myocardial work variables showed statistical correlation with cardiac involvement in sarcoidosis patients. However, there was no incremental value of myocardial work indexes compared to the isolated use of GLS.

Determination of rare earth elements in synthetic calcium phosphates by high-resolution continuum source electrothermal atomic absorption spectrometry

Ceramic, cement and composite biomaterials have been developed based on hydroxyapatites (HA) and tricalcium phosphates (TCP), which are analogous in phase and chemical composition to the mineral component of bone tissue. The crystal structures of HA and TCP are arranged in isomorphic substitutions. Recently, research has focused on the modification of HA and TCP structures with ions of various metals, including rare earth ions (REEs), with the aim of creating materials with a range of beneficial properties for medical applications. REEs are known to have a number of useful properties, including antibacterial, antitumour, catalytic, magnetic and luminescent properties. The replacement of some of the Ca ions in the structures of HA and TCP with REE ions therefore makes it possible to obtain a material with biocompatibility and biological activity, giving it the required properties depending on the REE used and its concentration. In order to achieve the specified properties, it is necessary to control not only the structure (phase composition, lattice parameters of the powders) and the presence of characteristic functional groups, but also the chemical elemental composition. Modifications of hydroxyapatites and tricalcium phosphates containing from one to several different alloying elements are currently being developed. Various analytical methods are used for this purpose, including X-ray, atomic emission and a number of others. This article is devoted to the study of the analytical capabilities of the method of atomic absorption spectrometry with electrothermal atomization and a continuous spectrum source in relation to the determination of Eu and Yb in hydroxyapatites and tricalcium phosphates. The article considers the optimal conditions and modes of analysis, including temperature-time programs, the use of modifiers, the construction of calibration curves, and other factors that can be adjusted for more precise results. The results demonstrated the possibility of simultaneous determination of both Eu and Yb in the concentration range of 0.09 to 2 wt.%, with a relative standard deviation of less than 6 rel.%.