Error Bars Research Articles

Synthesis of an Ultra-high Hardness Nanostructured AlSi10Mg Alloy via A Hybrid Laser Powder Bed Fusion/High-Pressure Torsion Approach

The hybrid combination of laser powder bed fusion (L-PBF) and high-pressure torsion, respectively an additive manufacturing (AM) and severe plastic deformation (SPD) has recently emerged as an important field of study due to the ability to produce novel nanostructured metals/alloys with simultaneous enhancements in mechanical (hardness, yield and tensile strengths) and functional (corrosion and wear) performances. Pioneering studies on the hybrid L-PBF/HPT approach was focused on 316L stainless steel (316L SS) and AlCuMg alloys due to their widespread engineering applications. AlSi10Mg, an alloy widely used in the automotive industry is expected to benefit from this hybrid combination but has not been investigated before. Thus, this study aims to investigate the microstructural features and hardness of the nanostructured AlSi10Mg attained by the hybrid L-PBF/HPT technique via transmission electron microscopy (TEM) and Vickers microhardness (HV) measurements, respectively. The results showed novel microstructures, including nano-scale grain sizes (< 200 nm), nano-sized Mg2Si precipitates (~200 nm), and dense dislocation networks. The average hardness value was determined as 230 ± 20 HV, homogeneously distributed throughout the disk surface as indicated by the low deviation (error bar). The microstructures of L-PBF/HPT-synthesised AlSi10Mg are different and significantly refined than conventionally cast AlSi10Mg, which contributed to the two- to four-fold hardness (typical HV values of as-cast AlSi10Mg ranges from 60 – 68 HV) increase via grain boundary and dislocation strengthening mechanisms.

Evidence-Based Certification of Quantum Dimensions.

Identifying a reasonably small Hilbert space that completely describes an unknown quantum state is crucial for efficient quantum information processing. We introduce a general dimension-certification protocol for both discrete and continuous variables that is fully evidence based, relying solely on the experimental data collected and no other unjustified assumptions whatsoever. Using the Bayesian concept of relative belief, we take the effective dimension of the state as the smallest one such that the posterior probability is larger than the prior, as dictated by the data. The posterior probabilities associated with the relative-belief ratios measure the strength of the evidence provide by these ratios so that we can assess whether there is weak or strong evidence in favor or against a particular dimension. Using experimental data from spectral-temporal and polarimetry measurements, we demonstrate how to correctly assign Bayesian plausible error bars for the obtained effective dimensions. This makes relative belief a conservative and easy-to-use model-selection method for any experiment.

ZTF SN Ia DR2: Peculiar velocities' impact on the Hubble diagram

Type Ia supernovae ( are used to determine the distance-redshift relation and build the Hubble diagram. Neglecting their host-galaxy peculiar velocities (PVs) may bias the measurement of cosmological parameters. The smaller the redshift, the larger the effect is. We used realistic simulations of observed by the Zwicky Transient Facility (ZTF) to investigate the effect of different methods of taking PVs into account. We studied the impact of neglecting galaxy PVs and their correlations in an analysis of the Hubble diagram. We find that it is necessary to use the PV full covariance matrix computed from the velocity power spectrum to take the sample variance into account. Considering the results we have obtained using simulations, we determine the PV systematic effects in the context of the ZTF SN Ia DR2 sample. We determine the PV impact on the intercept of the Hubble diagram, $a_B$, which is directly linked to the measurement of $H_0$. We show that not taking into account PVs and their correlations results in a shift in the $H_0$ value of about $1.0$ and a slight underestimation of the $H_0$ error bar.

High-Energy Reaction Dynamics of N3.

The atom-exchange and atomization dissociation dynamics for the N(4S) + N2(1Σg+) reaction are studied using a reproducing kernel Hilbert space (RKHS)-based, global potential energy surface (PES) at the MRCI-F12/aug-cc-pVTZ-F12 level of theory (MRCI, multireference configuration interaction). For the atom exchange reaction (NANB + NC → NANC + NB), computed thermal rates and their temperature dependence from quasi-classical trajectory (QCT) simulations agree to within error bars with the available experiments. Companion QCT simulations using a recently published CASPT2-based PES confirm these findings. For the atomization reaction, leading to three N(4S) atoms, the computed rates from the RKHS-PES overestimate the experimentally reported rates by 1 order of magnitude, whereas those from the permutationally invariant polynomial (PIP)-PES agree favorably, and the T dependence of both computations is consistent with the experiment. These differences can be traced back to the different methods and basis sets used. The lifetime of the metastable N3 molecule is estimated to be ∼200 fs depending on the initial state of the reactants. Finally, neural-network-based exhaustive state-to-distribution models are presented using both PESs for the atom exchange reaction. These models will be instrumental for a broader exploration of the reaction dynamics of air.

Predissociation-based measurements of bond dissociation energies: US2, OUS, and USe.

The uranium-containing molecules US2, OUS, and USe have been investigated using a pulsed laser ablation supersonic beam molecular source with time-of-flight mass spectrometric detection. Spectra have been recorded using the resonant two-photon ionization method over the spectroscopic range from 277 to 238nm. These species have a myriad of excited electronic states in this spectroscopic region, leading to spectra that are highly congested and appear quasicontinuous. Sharp predissociation thresholds are observed, allowing precise bond dissociation energies to be measured. In the case of the triatomic molecules, it was necessary to use one laser for excitation and a delayed laser for ionization in order to observe a sharp predissociation threshold that allowed a precise bond dissociation energy to be measured. The resulting thermochemical values are D0(SU-S) = 4.910 ± 0.003eV, D0(OU-S) = 5.035 ± 0.004eV, and D0(USe) = 4.609 ± 0.009eV. These results provide the first measurement of D0(USe) and reduce the error limits in the previous values of D0(SU-S) and D0(OU-S) by a factor of more than 70.

Peculiarities of the shape and size of the mandible and the lower dentition with taking into account gender and craniotype

The aim of the study: establishment of actual intravital craniometric characteristics of the shape and dimensions of the mandible and lower dentition of an adult person depending on gender and craniotype. Research materials and methods: the work used dry bone preparations of whole or fragmented human skulls of both sexes in the amount of 39 units, from the collection of the Department of Human Anatomy of the Kharkiv National Medical University, and the results of CT studies of the head of adult people without existing bone tissue pathologies, totaling 85 observations. The basis of establishing a craniotype is the principle of calculating the general facial or facial index, which allows classifying anatomical objects according to the shape of the head structure. Research results: the straight length of the mandible in adult leptoprosops males is from 88.5 mm to 102.4 mm, for women - from 86.3 mm to 100.7 mm; in mesoprosops men, this parameter gradually decreases to the level - from 81.3 mm to 95.7 mm, in women - from 80.7 mm to 94.9 mm; in euryprosops, the index is the smallest and ranges from 79.7 mm to 91.5 mm in males and from 78.5 mm to 90.8 mm in females. The opposite trend with significant ranges of variation is established for the angular width of the bone. Thus, in male leptoprosops, this parameter was determined from 84.6 mm to 97.5 mm, in female representatives - from 83.6 mm to 96.3 mm; in mesoprosops men, it increased from 89.1 mm to 105.3 mm, in women - from 87.9 mm to 103.1 mm; in euryprosops, regardless of sex, it reached its peak values, from 94.5 mm to 116.1 mm and from 92.7 mm to 114.1 mm, respectively. The height of the mandibular body also showed a certain dependence on the type of skull structure, in leptoprosops men it tended to the highest values ​​and was fixed at the level from 29.1 mm to 38.9 mm, as well as in women - from 27.5 mm to 37.8 mm; at the same time, in mesoprosops men, the size decreased from 25.9 mm to 36.3 mm, in women, in turn, from 24.6 mm to 35.1 mm; in euryprosops men, this parameter ranged from 22.3 mm to 33.1 mm, and next to women - from 21.9 mm to 31.9 mm, it was at the level of the lowest indicators. When analyzing such a complex and multidirectional parameter as the arch of the mandible, it was also possible to obtain a characteristic of its dependence on the type of structure of the facial department of the skull. It was established that the range with the smallest values ​​of the length of the arc is characteristic of leptoprosops, ranging from 135.8 mm to 149.4 mm in males and from 133.5 mm to 147.3 mm in females; average indices are characteristic of men - from 139.1 mm to 154.6 mm and women - from 136.4 mm to 151.2 mm with a mesoprosopic craniotype; in euryprosops of both sexes, the index tends to the greatest values ​​at the level of 141.2 mm to 158.3 mm and from 139.7 mm to 155.7 mm, respectively. Conclusions: the main craniometric parameters of the mandible are significantly dependent on the type of structure of the facial department of the skull. Thus, the leptoprosopic craniotype is characterized by maximum values ​​of longitudinal and height dimensions with minimal indicators of width and arc length. Mesoprosops are characterized by the definition of intermediate, averaged values ​​equidistant from marginal, terminal forms. In representatives with the euryprosopic type of skull structure, a significant decrease in the length and height of the jaw with a significant increase, up to the maximum values, width and length of the arch was observed. At the same time, unlike leptoprosops, which had a shortened and pointed arch, in euryprosops, the arch tended to be smoothed and lengthened. The assessment by sex leads to the fact that all sizes of the lower jaw predominate in men, but, nevertheless, a certain number of differences in indicators were within the limits of statistical error, which does not allow making absolute conclusions in this matter

Elemental composition of <i>Vaccinium vitis-idaea</i> и <i>V. myrtillus</i> (Ercaceae) leaves in green moss pine forests under aerotechnogenic pollution in the Komi Republic

The paper aims at the impact of aerotechnogenic emissions from the largest in the European North pulp and paper production enterprise, namely JSC «Syktyvkar Timber Processing Complex», on the elemental composition (N, S, C, P, K, Ca, Mg, Na, Al, Fe, Mn) of lingonberry and blueberry leaves as the dominant dwarf shrubs in green moss pine forests. The leaves of blueberry and lingonberry growing in pine stands both in the background and contaminated areas were identified to have similar average values of the mass fraction of ash elements in 2009. The content of ash elements in the leaves of dwarf shrubs from the background pine forests was higher than that in leaves collected from the impact zone in 2018. The average values of the mass fraction of ash elements in blueberry leaves were found to access those in lingonberry leaves by 1,5 time both in the background and contaminated areas. There was no regular change in the content of elements in leaves of dwarf shrubs with distance from the source of emission. The differences in the sulfur content in leaves of dwarf shrubs for 2009 and 2018 were within the error limits. No significant differences were found in the values of the mass fraction of nitrogen in blueberry and lingonberry leaves for pine stands located at different distances from the emission source. The nitrogen content in lingonberry leaves was significantly lower than that in blueberry leaves for both observation periods. There was no significant difference in the total nitrogen content in blueberry and lingonberry leaves between 2009 and 2018.

Distributed safe formation tracking control of multiquadcopter systems using barrier Lyapunov function.

Coordinating the movements of a robotic fleet using consensus-based techniques is an important problem in achieving the desired goal of a specific task. Although most available techniques developed for consensus-based control ignore the collision of robots in the transient phase, they are either computationally expensive or cannot be applied in environments with dynamic obstacles. Therefore, we propose a new distributed collision-free formation tracking control scheme for multiquadcopter systems by exploiting the properties of the barrier Lyapunov function (BLF). Accordingly, the problem is formulated in a backstepping setting, and a distributed control law that guarantees collision-free formation tracking of the quads is derived. In other words, the problems of both tracking and interagent collision avoidance with a predefined accuracy are formulated using the proposed BLF for position subsystems, and the controllers are designed through augmentation of a quadratic Lyapunov function. Owing to the underactuated nature of the quadcopter system, virtual control inputs are considered for the translational (x and y axes) subsystems that are then used to generate the desired values for the roll and pitch angles for the attitude control subsystem. This provides a hierarchical controller structure for each quadcopter. The attitude controller is designed for each quadcopter locally by taking into account a predetermined error limit by another BLF. Finally, simulation results from the MATLAB-Simulink environment are provided to show the accuracy of the proposed method. A numerical comparison with an optimization-based technique is also provided to prove the superiority of the proposed method in terms of the computational cost, steady-state error, and response time.

A Comprehensive Physiologically Based Pharmacokinetic Model for Predicting Vildagliptin Pharmacokinetics: Insights into Dosing in Renal Impairment.

Physiologically based pharmacokinetic (PBPK) modeling is of great importance in the field of medicine. This study aims to construct a PBPK model, which can provide reliable drug pharmacokinetic (PK) predictions in both healthy and chronic kidney disease (CKD) subjects. To do so, firstly a review of the literature was thoroughly conducted and the PK information of vildagliptin was collected. PBPK modeling software, PK-Sim®, was then used to build and assess the IV, oral, and drug-specific models. Next, the average fold error, visual predictive checks, and predicted/observed ratios were used for the assessment of the robustness of the model for all the essential PK parameters. This evaluation demonstrated that all PK parameters were within an acceptable limit of error, i.e., 2 fold. Also to display the influence of CKD on the total and unbound AUC (the area under the plasma concentration-time curve) and to make modifications in dose, the analysis results of the model on this aspect were further examined. This PBPK model has successfully depicted the variations of PK of vildagliptin in healthy subjects and patients with CKD, which can be useful for medical practitioners in dosage optimization in renal disease patients.

Relativistic coupled-cluster simulation of the kinetics of the hydrolysis of uranium hexafluoride

Uranium hexafluoride ( UF 6 ) is used ubiquitously in the nuclear fuel cycle. Its spontaneous hydrolysis in the presence of atmospheric moisture is well known but the associated reaction mechanism is poorly understood. Here a computational study was undertaken with the aim of characterizing the rate-limiting step of the hydrolysis of UF 6 under dry conditions. Toward this end, we began by examining the convergence of various energy contributions to the atomization enthalpy ( Δ H at ) of UF 6 and its hydrolysis product, UO 2 F 2 . This enabled a refinement of our previous composite method, resulting in a composite method with improved accuracy that also scales well by leveraging existing massively-parallel codes. We find that extremely high levels of theory are required to obtain Δ H at within experimental error bars, in agreement with the literature. Having calibrated our composite scheme, we proceed to investigate approximations appropriate for computing accurate binding energies and barrier heights on the potential energy surface governing the hydrolysis of UF 6 . In combination with high-accuracy relative energies, a master equation approach is used to generate rate constants, and comparisons are made with recent measurements [Richards et al., RSC Adv., 2020, 10, 34729]. Based on kinetic and equilibrium arguments, we conclude that the hydrolysis of U F 6 , when proceeding under very dry conditions, is unlikely to be initiated via U F 6 + H 2 O → UF 5 OH + HF type reactions. Finally, computed equilibrium constants and rate coefficients are tabulated for the temperature range 300–1800 K.

Evaluation of artificial neurocomputing algorithms and their metacognitive robustness in predictive modeling of fuel consumption rates during tillage

Artificial intelligence (AI) requires complex neurocomputing algorithms (NCAs) for robustness in predictive modeling. Since 1990, a plethora of NCAs have evolved, challenging selection of the most intelligent and error-tolerant model for predicting fuel consumption rate (ØFuel) in tillage. This study adopted 12 recent NCAs in modeling 72 neurocomputing architectures and evaluated their metacognitive robustness in predicting ØFuel using 80 tillage datasets. These included Levenberg-Marquardt (trainlm), Quasi-newton (trainbfg), Powell-Beale conjugate gradient (traincgb), Scaled conjugate gradient (trainscg), Fletcher-reeves conjugate gradient (traincgf), Polak-ribiére conjugate gradient (traincgp), Onestep secant (trainoss), Bayesian regularization (trainbr), Resilient backpropagation (trainrp), Gradient descent (traingd), Learning rate gradient descent (traingdx) and Gradient descent momentum (traingdm). Tillage variables were sequentially subjected to NCA architectures learning on logsig, Purelin, and tansig neuro-activation functions, targeting 1000 epochs. Neuro-cognitive performance was evaluated through broad multi-criteria of regressed neuron input–output functions using heuristic and accuracy metrics, i.e., training time (t), number of hidden layers (NL), and neurons (Nn), optimal epoch (Eopt), Coefficient of correlation (R) and determination (R2), Mean square error (MSE), Root mean square error (RMSE), Mean absolute error (MAE), Mean absolute percentage error (MAPE), Sum square error (SSE), Prediction scatter (Tscatter), Coefficient of variation (CV) and Prediction accuracy (PA). Prediction reliability and robustness were evaluated using a20-index (a20), Willmott’s index of agreement (IOA), Index of scatter (IOS), Variance accounted for (VAF), Performance index (PI), Total score rank (ξtotal), Sensitivity index (SAij) and Anderson-Darling (AD) test. Results indicated that varying NL and Nn did not correspond with t, Eopt and PA but only occurred in single-layered trainbr and double-layered trainlm. Although PA increased at reduced convergence error limits, relationships among Eopt, t, and PA were unclear. Single-layered trainbr (14-20-1) outperformed all NCAs with R (0.9993), R2 (0.9986), MSE (6.34e-06), RMSE (0.0025), MAE (0.003), MAPE (1.4e-06), SSE (8e-04), R2All (0.9998) Tvalue (1.0), CV (3.232 %) and PA (99.81 %). However, trainlm (14-20-10-1) most accurately modeled double-layered architectures i.e. R (0.9932), R2 (0.9864), MSE (7.4e-05), RMSE (0.009), MAE (0.004), MAPE (0.003), SSE (0.003), R2All (0.9929), Tvalue (0.9998), CV (3.212 %) and PA (97.8 %). Nonetheless, trainbr (14-20-1) achieved the best reliability metrics of a20 (100 %), VAF (99.98 %), IOA (1.00), PI (1.9971), IOS (0.0115), ξtotal (284) and AD-test (2.6852). Sensitivity analysis revealed that tractive force had the most significant influence on ØFuel while tire inflation pressure had the least. Learning on transig neuro-activation function in single-layered neural network, metacognitive robustness of trainbr is superiorly merited for predicting ØFuel during tillage.

Utilizing compositions of zircon and apatite for prospecting of Cu-Mo-Auporphyry mineralization in the Pekinsky and Tessemsky granitoid massifs of the Taimyr-Severozemelskaya folded area

Research subject. The Tessemsky granite massif is located in the North Taimyr tectonic zone, surrounded by Cambrian rocks. The Pekinsky granite massif is located within the Central Taimyr zone, surrounded by metamorphosed Proterozoic rocks. Aim. To develop a methodology for using the composition of accessory granitoid minerals when prospecting Cu-Mo-Au-porphyry mineralization on the example of the Pekinsky and Tessemsky granitoid massifs of the Taimyr Peninsula. Materials and methods. Accessory zircon and apatite contained in two granitoid samples from the Pekinsky massif (P1, P2) and two granitoid samples from the Tessemsky massif (T2, T3) were studied. Their mineral composition was examined using an EPMA Cameca SX100 instrument. The element content in minerals was determined by LA-ICPMS using an NexION 300S instrument equipped with an NWR 213 attachment. Results. Most of the zircons from the Pekinsky and Tessemsky massifs were formed at T < 738°C in oxidized magma with ΔFMQ of 0.6–2.6, which is a favorable sign for the identification of Cu-Mo-Au-porphyry mineralization. Zircons are characterized by elevated (Eu/Eu*)Y and (Ce/Nd)n/Y ratios, which is also a favorable, though not a strongly reliable, sign for identifying porphyry mineralization. The Eu/Eu* and Sr/Y ratios in the apatites from the Tessemsky massif are higher than those in the apatites from the Pekinsky massif. The rock compositions of both massifs fall within the fields of adakites on the classification diagrams. The estimates of oxygen fugacity (logfO2) calculated from Mn in apatites for four samples agree well within the error limits. Conclusion. Specific features of using the composition of accessory minerals (zircon and apatite) for prospecting the Cu-Mo-Au-porphyry mineralization associated with granitoids were considered. Accessory indicator minerals can be used to rank granitoid massifs in order to assess their ore content. The example of two granite intrusions of the Taimyr Peninsula made it was possible to show that the Tessemsky massif is more promising for the discovery of associated Cu-Mo-Auporphyry mineralization than the Pekinsky massif.

Assessing pH-Dependent Conformational Changes in the Fusion Peptide Proximal Region of the SARS-CoV-2 Spike Glycoprotein.

One of the entry mechanisms of the SARS-CoV-2 coronavirus into host cells involves endosomal acidification. It has been proposed that under acidic conditions, the fusion peptide proximal region (FPPR) of the SARS-CoV-2 spike glycoprotein acts as a pH-dependent switch, modulating immune response accessibility by influencing the positioning of the receptor binding domain (RBD). This would provide indirect coupling of RBD opening to the environmental pH. Here, we explored this possible pH-dependent conformational equilibrium of the FPPR within the SARS-CoV-2 spike glycoprotein. We analyzed hundreds of experimentally determined spike structures from the Protein Data Bank and carried out pH-replica exchange molecular dynamics to explore the extent to which the FPPR conformation depends on pH and the positioning of the RBD. A meta-analysis of experimental structures identified alternate conformations of the FPPR among structures in which this flexible regions was resolved. However, the results did not support a correlation between the FPPR conformation and either RBD position or the reported pH of the cryo-EM experiment. We calculated pKa values for titratable side chains in the FPPR region using PDB structures, but these pKa values showed large differences between alternate PDB structures that otherwise adopt the same FPPR conformation type. This hampers the comparison of pKa values in different FPPR conformations to rationalize a pH-dependent conformational change. We supplemented these PDB-based analyses with all-atom simulations and used constant-pH replica exchange molecular dynamics to estimate pKa values in the context of flexibility and explicit water. The resulting titration curves show good reproducibility between simulations, but they also suggest that the titration curves of the different FPPR conformations are the same within the error bars. In summary, we were unable to find evidence supporting the previously published hypothesis of an FPPR pH-dependent equilibrium: neither from existing experimental data nor from constant-pH MD simulations. The study underscores the complexity of the spike system and opens avenues for further exploration into the interplay between pH and SARS-CoV-2 viral entry mechanisms.

Method for Two-Stage Radar Measurement of the Blade Repetition Rate of a Propeller-Driven Aircraft

Introduction. Radar images of aircraft propellers can significantly improve the quality of their recognition and protection against simulating interference. Such images can be obtained using algorithms based on an inverse antenna aperture synthesis. A key factor determining the quality of image acquisition is the accuracy of the rotor blade rotation frequency measurement. In 2019, a method for measuring the blade repetition rate was proposed, which is based on convolution of the "secondary" signal modulation spectrum while simultaneously eliminating the influence of the Doppler frequency of the signal reflected from the aircraft body. In sequential analysis, the number of cycles is determined by the ratio of the maximum blade repetition rate (hundreds of hertz) to the discrete frequency shift (thousandths of hertz). In this case, to solve the measurement problem, the required number of cycles should be hundreds of thousands, which is expensive in terms of practical implementation.Aim. Development of a two-stage method for measuring the blade repetition rate, which allows the number of signal convolution cycles to be reduced by hundreds of times.Materials and methods. The proposed method is aimed at implementing adaptation circuits to an a priori unknown rotor speed of an aircraft, which can be determined based on the blade rotation frequency. The method involves measuring the blade frequency in two stages: a rough measurement of the blade frequency rate followed by its accurate measurement within the limits of the maximum errors of the rough measurement.Results. A method for a two-stage measurement of the blade repetition rate as applied to the construction of radar images of aircraft propellers is proposed. The feasibility of the method is illustrated by the example of a signal reflected from a Mi-8 helicopter. The requirements to the measurement error of the blade repetition rate and to the frequency analysis step at the precise measurement stage are formulated. The requirement to the repetition rate of probing signals is substantiated, the fulfillment of which ensures an unambiguous restoration of the spectrum of "secondary" modulation of the signal reflected from the blades of a propeller-driven aircraft.Conclusion. The developed method for a two-stage measurement of the blade repetition rate ensures the adaptation of algorithms for constructing radar images of aircraft propellers to their rotation frequency.

Local decorrelation for error bars in time series

Local decorrelation for error bars in time series

FLRW cosmology in Weyl type f(Q) gravity and observational constraints

Inspired by various works in a Weyl type f(Q) gravity to reduce some serious problems in General Relativity Theory (GR), we develop a model of the universe in a Weyl type f(Q) gravity which shows the transition from a decelerating state to an accelerating state of the universe at present when we consider a particular functional form of the f(Q) gravity as f(Q)=(H02)(α1+α2log(H0−2Q)). We numerically solve Weyl type f(Q) gravity field equations and obtain the numerical solutions to the Hubble parameter, deceleration parameter, distance modulus, and the apparent magnitudes of stellar objects using Ia Supernovae. Also, we obtain numerical solutions for the Weyl vector w, non-metricity scalar Q, and the Lagrangian multiplier λ appearing in the action of f(Q) gravity. We compare our model with the error bar plots of the observed Hubble dataset of 77 points, SNIa datasets of 580 points, and 1048 supernova Pantheon datasets of the apparent magnitudes, and the statistical analysis using Baryon Acoustic Oscillations (BAO). It is found that our results fit well with the observed values. The model envisages a unique feature: although the universe is filled with perfect fluid as dust whose pressure is zero, the Weyl vector dominance f(Q) creates acceleration.

An insight into the mechanical and morphological properties of palm oil plasticized high density polyethylene-chitosan composites

An experimental analysis of the mechanical properties of maleic anhydride compatibilized high density polyethylene-chitosan composites plasticized with palm oil were investigated. The effect of chitosan as filler (0, 2.5, 5, 7.5 and 10 wt%) on the mechanical properties of the injection moulded samples and its comparison with the corresponding palm oil plasticized with the optimised composite system has been performed. The mechanical properties of the melt mixed composites were studied and compared. An increase of 11.3 % in tensile strength, 9.4% in impact strength and 44.4 % increase in Young's modulus for 5 wt% chitosan loaded composite system was obtained when compared with the neat HDPE system. Furthermore, the addition of 5 wt% palm oil to the optimised system increased its impact strength to 102 kJ/m2 when compared to the neat high density polyethylene system without chitosan. The improved compatibility between high density polyethylene and chitosan has been further confirmed through the morphological analysis. Finite element analysis of the tensile properties showed comparable values with the experimental values within acceptable error limits. This study led to the development of a bio-based material having better mechanical performance which can be used in bone-tissue engineering applications.

An improved manifold-projection trajectory based method for chemical kinetic mechanism reduction

An improved manifold-projection trajectory based dimension reduction algorithm (MTDR) to automatically generate skeletal chemical kinetic mechanisms was proposed and validated in this study. This algorithm is implemented by constructing an approximate manifold-based trajectory of the combustion system using Euclidean distances between two adjacent points and cosine similarities between two adjacent vectors in the manifold space, and then evaluating the importance of species by calculating the error of manifold-based trajectories before and after the projection of the manifold. In this method, the nature of the combustion system is well reflected since the combustion process information can be captured by the location of the state point in the manifold space. The calculation during the reduction process is simplified by using the manifold-based trajectory instead of the complex differential equations. Compared to our previous work, this study improves the prediction accuracy of the reduced mechanisms through a more comprehensive error evaluation in the mechanism reduction process. The detailed mechanisms of fuels including iso-cetane, iso-octane and gasoline surrogate mixtures of toluene, iso-octane and n-heptane were reduced to portray the prowess of the algorithm. It’s demonstrated that the number of species of the fuels is reduced from 492, 254 and 1389 to 95, 87 and 427 within an acceptable error, respectively. Meanwhile, the case of iso-octane mechanism reduction was chosen to compare the performance of MTDR with traditional methods including path flux analysis (PFA) and directed relation graph with error propagation and sensitivity analysis (DRGEPSA), and it is shown that the MDTR can generate more compact mechanism under a broad range of error limits.

On the Need to Take Measurement Error into Account When Carrying Out Activities in the Field of Environmental Protection

An analysis of the requirements of regulatory documents of the Russian Federation for measurements carried out to determine the values of quality indicators of natural environments (atmospheric air, soil, water) has been presented. It has been shown that when determining the true value of the content of a pollutant in environmental components, as well as when comparing measurement values with each other or with limit values (including when establishing the excess of a certain content of a controlled indicator in relation to the established standard), it is necessary to take into account the measurement range and limits of permissible error. The conclusion has been illustrated with specific examples that in case of violation of the requirements of regulatory documents and neglect of the measurement error range, the results obtained from laboratory tests cannot be objective, reliable and justified.

The Effect of Preoperative Carbohydrate-containing Fluid Consumption on Maternal Oxidative Stress Markers During Elective Cesarean Delivery

PurposeThe purpose of this study was to evaluate the effect of carbohydrate loading prior to the cesarean surgery under spinal anesthesia on thiols and ischemia-modified albumin (IMA) levels. DesignProspective, randomized placebo-controlled study. MethodsSeventy-nine pregnant women planned for cesarean sections under spinal anesthesia at Karaman Training and Research Hospital were randomized into a control group (group C) (n = 42), and an oral carbohydrate preloading group (group OCH) (n = 37). OCH loading requires consuming 400 mL the night before surgery and 200 mL up to 2 hours before anesthesia. Group OCH consumed an oral carbohydrate-rich beverage (Nutricia-Fantomalt), and group C consumed an equal volume of water. This study investigated thiol-disulfide homeostasis after preoperative carbohydrate consumption. Preoperative gastric fluid, volume, antral cross-sectional area, hypotension following the birth, and fetal blood gas parameters were compared across groups. FindingsThiols and IMA levels did not differ across groups before and after surgery (P > .05). Gastric ultrasonography showed similar antral cross-sectional area and stomach volume between groups (P = .172, P = .128, respectively). When surgery caused hypotension, group OCH received more ephedrine for surgery-induced hypotension, although this difference is not statistically significant (P = .704). A clustered error bar (95% confidence interval) plot with an interpolation line was used for a time-based comparison of mean differences in heart rate and mean arterial pressure between the groups. ConclusionsThis study supports that mothers' thiols and IMA levels were unaffected by preoperative OCH loading before cesarean surgery. We did not examine thiol and its derivatives in umbilical cord blood; hence, we can not comment on thiol/disulfide homeostasis levels in neonates.