bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency and Severity of Chlorothiazide-Induced Hyponatremia in the Neonatal Intensive Care Unit
Authors: Harkin Maura , Johnson Peter N. , Neely Stephen B. , White Lauren , Miller Jamie L.
Published: January 2021

Objective Although thiazide diuretics are commonly used in the neonatal intensive care unit (NICU), the risk of thiazide-induced hyponatremia in infants has not been well documented. The primary objective of this study was to determine the frequency and severity of hyponatremia in neonates and infants receiving enteral chlorothiazide. Secondary objectives included identifying: (1) percent change in serum sodium from before chlorothiazide initiation to nadir, (2) time to reach nadir serum sodium concentration, and (3) percentage of patients on chlorothiazide receiving sodium supplementation.

Study Design This was a retrospective cohort study of NICU patients admitted between July 1, 2014, and July 31, 2019, who received ≥1 dose of enteral chlorothiazide. Mild, moderate, and severe hyponatremia were defined as serum sodium of 130 to 134 mEq/L, 120 to 129 mEq/L, and less than 120 mEq/L, respectively. Data including serum electrolytes, chlorothiazide dosing, and sodium supplementation were collected for the first 2 weeks of therapy. Descriptive and inferential statistics were performed in SAS software, Version 9.4.

Results One hundred and seven patients, receiving 127 chlorothiazide courses, were included. The median gestational age at birth and postmenstrual age at initiation were 26.0 and 35.9 weeks, respectively. The overall frequency of hyponatremia was 35.4% (45/127 courses). Mild, moderate, and severe hyponatremia were reported in 27 (21.3%), 16 (12.6%), and 2 (1.6%) courses. The median percent decrease in serum sodium from baseline to nadir was 2.9%, and the median time to nadir sodium was 5 days. Enteral sodium supplements were administered in 52 (40.9%) courses. Sixteen courses (12.6%) were discontinued within the first 14 days of therapy due to hyponatremia.

Conclusion Hyponatremia occurred in over 35% of courses of enteral chlorothiazide in neonates and infants. Given the high frequency of hyponatremia, serum sodium should be monitored closely in infants receiving chlorothiazide. Providers should consider early initiation of sodium supplements if warranted.

Key Points
Prevalence, Risk Factors, and Short-Term Outcomes of Full-Term Low Birth Weight Infants Born at a Tertiary Academic Center: A Prospective Case–Control Study
Authors: Al-Wassia Heidi K. , Baarimah Shahd K. , Mohammedsaleh Asmaa H. , Alsulami Manal O. , Abbas Ragad S. , Rezqallah Raghad A. , Alawadi Raghda A. , Aljohani Saja M.
Published: January 2021

Objective Low birth weight (LBW) infants (<2,500 g) continued to be a global health problem because of the associated short- and long-term adverse outcomes. The study aimed to determine the prevalence, risk factors, and short-term outcomes of term LBW infants

Study Design A prospective and case–control study. All infants born consecutively from September 1, 2018 to August 31, 2019 were included. Cases, term LBW infants, were 1:1 matched to controls, appropriate for gestational age (AGA) term infants. Major congenital or chromosomal anomalies and multiple pregnancies were excluded.

Results The prevalence of term LBW in the studied period was 4.8%. Mothers of term LBW infants had significantly lower body mass index (p = 0.05), gained less weight (p = 0.01), had a history of previous LBW (p = 0.01), and lower monthly income (p = 0.04) compared with mothers of term AGA infants even after adjustment for confounders. A nonsignificant higher number of term LBW infants needed NICU admission, while their need for phototherapy was deemed significant.

Conclusion We identified nutritional and socioeconomic maternal factors that are significantly associated with LBW infants and should be targeted during antenatal visits to improve neonatal outcomes.

Key Points
Neonatal Outcomes at Extreme Prematurity by Gestational Age Versus Birth Weight in a Contemporary Cohort
Authors: Ausbeck Elizabeth B. , Allman Phillip Hunter , Szychowski Jeff M. , Subramaniam Akila , Katheria Anup
Published: January 2021

Objective The aim of the study is to describe the rates of neonatal death and severe neonatal morbidity in a contemporary cohort, as well as to evaluate the predictive value of birth gestational age (GA) and birth weight, independently and combined, for neonatal mortality and morbidity in the same contemporary cohort.

Study Design We performed a secondary analysis of an international, multicenter randomized controlled trial of delayed umbilical cord clamping versus umbilical cord milking in preterm infants born at 230/7 to 316/7 weeks of gestation. The current analysis was restricted to infants delivered <28 weeks. The primary outcomes of this analysis were neonatal death and a composite of severe neonatal morbidity. Incidence of outcomes was compared by weeks of GA, with planned subanalysis comparing small for gestational age (SGA) versus non-SGA neonates. Multivariable logistic regression was then used to model these outcomes based on birth GA, birth weight, or a combination of both as primary independent predictors to determine which had superior ability to predict outcomes.

Results Of 474 neonates in the original trial, 180 (38%) were included in this analysis. Overall, death occurred in 27 (15%) and severe morbidity in 139 (77%) neonates. Rates of mortality and morbidity declined with increasing GA (mortality 54% at 23 vs. 9% at 27 weeks). SGA infants (n = 25) had significantly higher mortality compared with non-SGA infants across all GAs (p < 0.01). There was no difference in the predictive value for neonatal death or severe morbidity between the three prediction options (GA, birth weight, or GA and birth weight).

Conclusion Death and severe neonatal morbidity declined with advancing GA, with higher rates of death in SGA infants. Birth GA and birth weight were both good predictors of outcomes; however, combining the two was not more predictive, even in SGA infants.

Key Points
A generalized permutation entropy for noisy dynamics and random processes
Authors: Amigó José M. , Dale Roberto , Tempesta Piergiulio
Published: January 2021

Permutation entropy measures the complexity of a deterministic time series via a data symbolic quantization consisting of rank vectors called ordinal patterns or simply permutations. Reasons for the increasing popularity of this entropy in time series analysis include that (i) it converges to the Kolmogorov–Sinai entropy of the underlying dynamics in the limit of ever longer permutations and (ii) its computation dispenses with generating and ad hoc partitions. However, permutation entropy diverges when the number of allowed permutations grows super-exponentially with their length, as happens when time series are output by dynamical systems with observational or dynamical noise or purely random processes. In this paper, we propose a generalized permutation entropy, belonging to the class of group entropies, that is finite in that situation, which is actually the one found in practice. The theoretical results are illustrated numerically by random processes with short- and long-term dependencies, as well as by noisy deterministic signals.
Thermal imaging of vibrational energy dissipated in a 2D acoustic black hole pit
Authors: Durand-Texte Thomas , Pelat Adrien , Penelet Guillaume , Gautier François , Sécail-Géraud Mathieu
Published: January 2021

An Acoustic Black Hole (ABH) is an efficient way to passively damp flexural vibrations in plates. It consists of an axisymmetric pit whose thickness gradually decreases down to a small value at its center, thus reducing progressively the local wavelength and increasing the amplitude of vibrations. A trapping effect occurs in the central area, in which a small patch of visco-elastic coating is sufficient to dissipate the localized energy in a very efficient way. The dissipated mechanical power produces a local heat release and so a local increase in temperature that is recorded by means of a high-speed infrared camera. In the stationary regime, the local temperature increase is the signature of the ABH efficiency. In the transient regime and before a characteristic time, the zones where the damping mechanisms are active and where vibrational energy is dissipated can be localized. The key role played by the constraining layer of visco-elastic material in the ABH efficiency is notably shown experimentally.
Polarization effects in laser-induced plasma lasers based on elements from the 13th group
Authors: Nagli L. , Stambulchik E. , Gaft M. , Raichlin Y.
Published: January 2021

We propose a model explaining polarization effects in laser-induced plasma lasers (LIPLs) of the 13th group elements, pumped by a linearly polarized laser beam. The model is based on considering optical transitions between magnetic sublevels involved in the pumping–generation cycle. The model reproduces experimentally observed LIPL polarization features under the np 2P1/2, 3/2 → n′s 2S1/2 pumping. On the other hand, polarization-resolved collisional-radiative modeling appears to be required for a quantitative explanation of the LIPL polarization when the np 2P1/2, 3/2 → n′d 2D1/2 pumping is used.
Flame stabilization enhancement by microjet-based virtual shock wave generators in a supersonic combustor
Authors: An Bin , Wang Zhenguo , Sun Mingbo
Published: January 2021

Two flow control methods, namely, the microjet array (MJA) and the conventional shock wave generator (SWG), were employed to enhance the chemical reaction in a strut-based supersonic combustor. The Mach number, stagnation temperature, and stagnation pressure of the inflow were 2.92 K, 1650 K, and 2.60 MPa, respectively. The combustor was fueled by hydrogen and liquid kerosene. The case without any flow control method (the baseline case) was also reported for comparison. It was found that the recirculation flow at the strut base was essential to flame stabilization. A self-sustaining hydrogen flame was achieved in the baseline case. However, a flame blow-off was observed when kerosene was injected into the combustor. This was attributed to the short residence time in the recirculation flow and the long ignition delay time of kerosene. To extend the operation envelope of the combustor, additional shock waves were introduced into the combustor using MJAs and SWGs. The shock waves successfully enlarged the recirculation flow at the strut base and significantly enhanced the chemical reaction. Self-sustaining hydrogen/kerosene flames were achieved in the cases with MJAs and SWGs. Although the chemical reaction in the case with MJAs was slightly less vigorous than that in the case with SWGs, these two cases shared the same combustion mode. The MJAs had the potential to replace the conventional SWGs in terms of flame stabilization enhancement.
Quantitative comparison of the magnetic proximity effect in Pt detected by XRMR and XMCD
Authors: Graulich Dominik , Krieft Jan , Moskaltsova Anastasiia , Demir Johannes , Peters Tobias , Pohlmann Tobias , Bertram Florian , Wollschläger Joachim , L. Mardegan Jose R. , Francoual Sonia , Kuschel Timo
Published: January 2021

X-ray resonant magnetic reflectivity (XRMR) allows for the simultaneous measurement of structural, optical, and magneto-optic properties and depth profiles of a variety of thin film samples. However, a same-beamtime same-sample systematic quantitative comparison of the magnetic properties observed using XRMR and x-ray magnetic circular dichroism (XMCD) is still pending. Here, the XRMR results (Pt L3 absorption edge) for the magnetic proximity effect in Pt deposited on the two different ferromagnetic materials Fe and Co33Fe67 are compared with quantitatively analyzed XMCD results. The obtained results are in very good quantitative agreement between the absorption-based (XMCD) and reflectivity-based (XRMR) techniques, taking into account an ab initio calculated magneto-optic conversion factor for the XRMR analysis. Thus, it is shown that XRMR provides quantitative reliable spin depth profiles important for spintronic and spin caloritronic transport phenomena at this type of magnetic interfaces.
Real-time imaging and tracking of microrobots in tissues using ultrasound phase analysis
Authors: Pane S. , Iacovacci V. , Sinibaldi E. , Menciassi A.
Published: January 2021

Ultrasound B-mode imaging has been employed to monitor single agents and collective swarms of microrobots in vitro and ex vivo in controlled experimental conditions. However, low contrast and spatial resolution still limit the effective employment of such a method in a medical microrobotic scenario. Doppler-based ultrasound appears as a promising tool for tracking microrobots in echogenic and dynamic environments as biological tissues. In this Letter, we demonstrate that microrobot displacements can be used as a special signature for their visualization within echogenic media, where B-mode fails. To this aim, we induced vibrations of a magnetic soft microrobot through alternated magnetic fields and used ultrasound phase analysis to derive microrobot features such as size and position over time. By exploiting vibrations, we were able to perform imaging and tracking of a low contrast microrobot both in tissue-mimicking phantom and in chicken breast. The axial resolution was 38 μm, which is four times smaller than the B-mode resolution with the employed equipment. We also performed real-time tracking of the microrobot's positions along linear trajectories with a linear velocity up to 1 mm/s. Overall, the reported results pave the way for the application of the proposed approach for the robust monitoring of medical microrobots in tissue.
Fourier transform detection of weak optical transitions in atoms undergoing cyclic routines
Authors: Schelfhout Jesse S. , Toms-Hardman Lilani D. , McFerran John J.
Published: January 2021

We demonstrate a means of detecting weak optical transitions in cold atoms that undergo cyclic (preparation, probing, and detection) routines with improved sensitivity. The gain in sensitivity is made by probing atoms on alternate cycles of a repeated experimental sequence, leading to regular modulation of the ground state atom population when at the resonance frequency. The atomic transition is identified by conducting a fast Fourier transform via an algorithm or instrument. We find an enhancement of detection sensitivity compared to more conventional scanning methods of ∼20 for the same sampling time, and can detect contemporary clock lines with fewer than 103 atoms in a magneto-optical trap. We apply the method to the (6s2) 1S0−(6s6p) 3P0 clock transition in 171Yb and 173Yb. In addition, the ac-Stark shift of this line in 171Yb is measured to be 0.19(3) kHz W−1 m2 at 556 nm.
Four-temperature kinetic model for CO2 vibrational relaxation
Authors: Kosareva A. , Kunova O. , Kustova E. , Nagnibeda E.
Published: January 2021

A four-temperature kinetic-theory approach for modeling vibrationally non-equilibrium carbon dioxide flows is developed. The model takes into account all kinds of vibrational–translational energy transitions and inter-mode vibrational energy exchange between symmetric, bending, and asymmetric CO2 modes. The key feature of the model is using the averaged state-resolved relaxation rates instead of conventional Landau–Teller expressions. Spatially homogeneous CO2 vibrational relaxation is studied using the state-to-state, new four-temperature and commonly used three-temperature models. Excellent agreement between four-temperature and state-to-state solutions is found, whereas using the three-temperature model with the Landau–Teller production rates leads to significant loss of accuracy. Numerical efficiency of various approaches is discussed as well as the ways for its improvement.
Transformation-induced plasticity in omega titanium
Authors: Zahiri Amir Hassan , Ombogo Jamie , Ma Tengfei , Chakraborty Pranay , Cao Lei
Published: January 2021

ω -titanium (Ti) is a high-pressure phase that is conventionally perceived to be brittle and nondeformable, although direct investigations of its deformation process remain scarce. In this work, we perform molecular dynamics simulations to study the deformation process of ω-Ti with initial defects and find that stress-induced ω→α martensitic transformation can cause extensive plasticity in ω-Ti under various loading directions. Moreover, for the first time, we demonstrate that four types of transformation twins—{112¯1}, {112¯2}, {101¯2}, and {101¯1} twins—can be formed through the ω→α martensitic phase transformation. This work advances the understanding of plastic deformation in ω-Ti and unveils the essential role of the metastable ω-phase in the formation of transformation twins.
Hydration motifs of ammonium bisulfate clusters show complex temperature dependence
Authors: Kreinbihl John J. , Frederiks Nicoline C. , Johnson Christopher J.
Published: January 2021

The role of water in the formation of particles from atmospheric trace gases is not well understood, in large part due to difficulties in detecting its presence under atmospheric conditions and the variety of possible structures that must be screened computationally. Here, we use infrared spectroscopy and variable-temperature ion trap mass spectrometry to investigate the structural motifs adopted by water bound to ammonium bisulfate clusters and their temperature dependence. For clusters featuring only acid–base linkages, water adopts a bridging arrangement spanning an adjacent ammonium and bisulfate. For larger clusters, water can also insert into a bisulfate–bisulfate hydrogen bond, yielding hydration isomers with very similar binding energies. The population of these isomers shows a complex temperature evolution, as an apparent third isomer appears with a temperature dependence that is difficult to explain using simple thermodynamic arguments. These observations suggest that the thermodynamics of water binding to atmospheric clusters such as these may not be straightforward.
Improved acetone gas sensing performance based on optimization of a transition metal doped WO3 system at room temperature
Authors: Pi Mingyu , Zheng Liyu , Luo Haoyue , Duan Simiao , Li Chenlu , Yang Jie , Zhang Dingke , Chen Shijian
Published: January 2021

This paper proposes an effective strategy of material system optimization to improve acetone gas sensing performance based on hydrothermally processed transition metal (Fe, Co or Ni)-doped WO3 materials. A detailed comparison of the capability of pure WO3 and X:WO3 (X = Fe, Co, Ni) to sense acetone gas at room temperature was performed. It was found that the sensitivity of Ni:WO3 nanoflowers to acetone was much higher than that of pure WO3, Fe:WO3 and Co:WO3 under white light irradiation. To obtain a highly sensitive acetone gas sensor, the molar doping ratio of Ni to WO3 was further optimized. It was found that 3%Ni:WO3 had the highest response–recovery speed and the best target gas selectivity. Acetone with a concentration as low as 2 ppm can be detected at room temperature (20 °C). The sensitivity enhancement mechanism of the Ni:WO3 gas sensor is also discussed. It is expected that under white light irradiation the proposed Ni-doped WO3 can be used as a highly sensitive and selective acetone gas sensor at room temperature.
Enhanced switching performance of resistance random access memories by an inserted copper tellurium layer
Authors: Chen Po-Hsun , Lin Chih-Yang , Chang Jing-Shuen , Tseng Yi-Ting , Huang Jen-Wei
Published: January 2021

In this work, we systematically investigate the effects of the insertion of the solid-state electrolyte material copper–tellurium (CuTe) in resistance random access memory (RRAM). The CuTe layer is inserted as Cu/CuTe/SiO2/TiN (top-to-bottom) and the device exhibits excellent resistance switching (RS) characteristics such as lower forming bias, a larger memory window and faster RS speed, compared to the Cu/SiO2/TiN device. This validates the effects of the inserted CuTe layer with a Cu electrode. Furthermore, an additionally fabricated Cu/CuTe/TiN device demonstrates that the CuTe layer can also successfully act as a middle insulator for the RRAM device, based on the obtained experimental results.
A method to obtain the wind field characteristics of super-large aperture radio telescope site based on single-point wind tower and numerical simulation
Authors: He Fei-Long , Xu Qian , Wang Na , Zhu Chun-Hua
Published: January 2021

The influence of wind on the pointing accuracy of large aperture radio telescopes is becoming increasingly serious, especially at high observing frequency. Obtaining the wind field characteristics efficiently is very important to reduce the wind disturbance on antenna structure. In this paper, an error evaluation of numerical simulation method is established based on the measured data of single point wind tower, and the wind field characteristics are obtained from the evaluated numerical simulation results combined with the measured data for the 110 m aperture QiTai radio Telescope (QTT) site. According to the simulation results, compared with the measured data, the root mean square error (RMSE) of wind speed is less than 1 m s−1, and the minimum wind speed RMSE is 0.2 m s−1. An analysis of the wind field characteristics of the QTT site suggests that the active wind resistance design of the antenna periphery should focus on the SSW (south-south-west) direction.
Gamma-ray bursts with extended emission: classifications, energy correlations and radiation properties
Authors: Zhang Xiao-Lu , Zhang Chuan-Tao , Li Xu-Juan , Su Fu-Fang , Dong Xiao-Fei , Chang Heon-Young , Zhang Zhi-Bin
Published: January 2021

Thanks to more and more gamma-ray bursts with measured redshift and extended emission detected by the recent space telescopes, it is urgent and possible to check whether those previous energy correlations still satisfy the particular sample involving only the bursts accompanied by tail radiations. Using 20 long and 22 short bursts with extended emission, we find that the popular γ-ray energy correlations of the intrinsic peak energy versus the isotropic energy (Amati relation) and the intrinsic peak energy versus the peak luminosity (Yonetoku relation) do exist in both short and long bursts. However, it is much better if these gamma-ray bursts with extended emissions are reclassified into two subgroups of E-I and E-II that make the above energy correlations more tight. As proposed by Zhang et al., the energy correlations can be utilized to distinguish these kinds of gamma-ray bursts in the plane of bolometric fluence versus peak energy as well. Interestingly, the peculiar short GRB 170817A belongs to the E-I group in the fluence versus peak energy plane, but it is an outlier of both the Amati and Yonetoku relations even though the off-axis effect has been corrected. Furthermore, we compare the radiation features between the extended emissions and the prompt gamma-rays in order to search for their possible connections. Taking into account all these factors, we conclude that gamma-ray bursts with extended emission are still required to model with dichotomic groups, namely E-I and E-II classes, which hint that they might have different origins.
The wide-field photometric system of the Nanshan One-meter Telescope
Authors: Bai Chun-Hai , Feng Guo-Jie , Zhang Xuan , Niu Hu-Biao , Eskandar Abdusamatjan , Pu Guang-Xin , Ma Shu-Guo , Liu Jin-Zhong , Jiang Xiao-Jun , Ma Lu , Esamdin Ali , Wang Na
Published: January 2021

The Nanshan One-meterWide-field Telescope is a prime focus system that is located at Nanshan Station of Xinjiang Astronomical Observatories. The field of view was designed to 1.5° × 1.5°, and the Johnson-Cousins UBVRI system was chosen as the main filter set. The telescope has been providing observation services for astronomers since September 2013. Variable source searching and time-domain surveys are the main scientific goals. The system’s test results are reported including linearity, dark current, bias, readout noise and gain of the CCD camera. The accurate instrumental calibration coefficients in UBVRI bands were driven with Landolt standard stars during photometric nights. Finally, the limiting magnitudes are given with signal-to-noise ratios and various exposure times for observers.
Statements of the boundary value problems in mathematical simulation of a quasistationary electric field in the atmosphere and ionosphere
Authors: Denisenko Valery
Published: January 2021

Boundary-value problems which have to be solved in the frame of the mathematical models of quasi-stationary electric fields and currents in the global conductor, that consists of the Earth’s ionosphere and the atmosphere are formulated. The approach based on the domain decomposition is used. A quadratic energy functional is constructed. It allows us to reduce the solution of the boundary value problem for a three-dimensional elliptic differential equation with asymmetric coefficients to minimizing of the functional. Estimates of the quadratic form in comparison with the Dirichlet principle for the Poisson equation are obtained. These estimates allow us to assess the condition number of the matrix of the system of linear algebraic equations, arising in the numerical solution to the problem.
Complete spectra of periodicities in the problems of differentiation of closely related bacterial genomes
Authors: Miroshnichenko L A , Gusev V D
Published: January 2021

Tandem repeats (periodicities) constitute a significant part of the genomes of various organisms. They are often used as molecular markers in problems of differentiation of related objects. As such, bacteria of pseudotuberculosis and plague are considered. Genetically, the pathogen causing plague, Yersinia pestis, is very similar to Yersinia pseudotuberculosis. A comparison is made of the full spectra of periodicities in the genomes of bacteria of both species. Their general and species-specific features have been identified, confirming the high classification potential of the used object description.
Numerical solution of the integral equations of the electromagnetic field in geosteering problems
Authors: Bondarenko A.V. , Velker N. N. , Kushnir D.Yu. , Dyatlov G.V. , Dashevsky Yu.A.
Published: January 2021

Extra-deep azimuthal resistivity measurements improve the depth of investigation up to 30 m from the wellbore. Interpretation of electromagnetic logging data in the neighbourhood of a well becomes an important technical problem. We present an efficient parallel method for computation of induction tool responses with multiple transmitter–receiver configurations in 2D pixel-based anisotropic model crossed by an arbitrary well trajectory. The cornerstone of the approach is volume integral equation method. We consider the conductivity distribution as a sum of background and anomalous conductivities. Background conductivity is 1D-layered. Anomalous conductivity has arbitrary 2D distribution. Electromagnetic fields are the superposition of background and anomalous fields. Background fields are calculated exactly using rigorous analytical solution for 1D-layered background model. With this approach, the 2D pixel-based model is treated as an extension of the 1D-layered model. The anomalous fields are required only in pixels with conductivity different from the conductivity of the 1D-layered model. Anomalous fields are calculated using convergent series of integral operators [1]. The approach takes into account conductivity anisotropy and allows obtaining both the exact solution and the fast approximate one. The convergence of approximate solution is investigated on some synthetic examples.
Computed tomography imaging using a short pulse source with angular discontinuity
Authors: Prokhorov I V , Yarovenko I P
Published: January 2021

This paper deals with an inverse problem that consists of the attenuation coefficient identification for the non-stationary radiation transfer equation. To solve the problem, we propose to use a pulsed radiation source with an angular discontinuity. We show that the solution to the radiation transfer equation is the sum of a discontinuous ballistic component and a continuous scattered one.The representation, allows us to obtain a formula for finding the attenuation coefficient. The uniqueness theorem for the solution of the inverse problem has been proved. Numerical experiments on a digital phantom show that the method proposed improves the reconstruction quality.
Inversion formulas and their finite-dimensional analogs for multidimensional Volterra equations of the first kind
Authors: Solodusha Svetlana , Antipina Ekaterina
Published: January 2021

The paper focuses on solving one class of Volterra equations of the first kind, which is characterized by the variability of all integration limits. These equations were introduced in connection with the problem of identifying nonsymmetric kernels for constructing integral models of nonlinear dynamical systems of the “input-output” type in the form of Volterra polynomials. The case when the input perturbation of the system is a vector function of time is considered. To solve the identification problem, previously introduced test signals of duration h (mesh step) are used in the form of linear combinations of Heaviside functions with deviating arguments. The paper demonstrates a method for obtaining the desired solution, developing a method of steps for a one-dimensional case. The matching conditions providing the desired smoothness of the solution are established. The mesh analogs of the studied integral equations based on the formulas of middle rectangles are considered.
Generation of a random anisotropic incompressible turbulent velocity field in accordance with the calculated flow statistics
Authors: Alexandrov A V , Dorodnicyn L W , Duben A P , Kolyukhin D R
Published: January 2021

On the base of Randomized Spectral Method (RSM), a new stochastic algorithm for the generation of homogeneous anisotropic turbulent velocity fields has been developed. This technique provides incompressibility of the obtained velocity field realizations simultaneously with the two main required statistical properties—the Reynolds-stress tensor and the turbulent energy spectrum. The method is computationally efficient and can easily be extended to the case of inhomogeneous turbulence.
About the effect of rounding on the properties of tests for testing statistical hypotheses
Authors: Yu Lemeshko B , Lemeshko S B
Published: January 2021

The paper shows the results of the influence of rounding errors on the distribution of statistics for testing various statistical hypotheses. It is shown that when rounding errors are commensurable with the standard deviation, measurement errors in the distribution of statistical tests (goodness-of-fit tests, homogeneity tests, normality tests, etc.) can significantly deviate from those that occur in the absence of rounding. Recommendations are given for applying the tests in such situations.
Flow simulation around circular cylinder at low Reynolds numbers using vortex particle method
Authors: Kuzmina K , Marchevsky I
Published: January 2021

The algorithm of the Viscous Vortex Domain method implemented in the author’s code VM2D is investigated. This code allows simulating 2D viscous incompressible flows and solving fluid-structure interaction problems. The verification of the algorithm, namely, the correctness of taking into account the viscosity effect, is performed on well-studied test problems of the flow simulation around a circular cylinder for Reynolds numbers in the range 20 . . . 200: the problem of the impulse start of the circular cylinder is considered, and the dependency of the flow separation angle on the Reynolds number is investigated. The comparison shows that for low Reynolds numbers (up to 140), the flow separation angle obtained in numerical simulations by using the VM2D code is in good agreement with the results of other studies. For higher Reynolds numbers, the estimated separation angle is slightly overestimated.
New decomposition method for the solutions of linear Schrödinger equation
Authors: Edeki S. O. , Onyemekara K. C.
Published: January 2021

The Schrödinger equation serves as the fundamental equation for quantum mechanics. In this article, we consider the theoretical and numerical solutions of Schrödinger’s linear equations. This is achieved using the new semi-analytical approach as an alternative to the classical Adomian Decomposition Method (ADM). The new method is referred to as Telescoping Decomposition Method. Some cases are considered; the results obtained display high level of convergence to their exact forms. The improved version is very useful and reliable; it requires less analytical effort, even without giving up precision. Thus, it is also highly recommended for the solution of related linear and nonlinear differential models in the fields of applied research.
Existence results for a resonant third-order problem with two dimensional kernel on the half-line
Authors: Imaga O. F. , Iyase S. A. , Bishop S. A.
Published: January 2021

The purpose of this research is to establish conditions that guarantee the solvability of a resonant third-order boundary value problem (BVP) on the half-line. The resonant problem is subject to integral and m-point boundary conditions while, the kernel of the differential operator is equal to two. The coincidence degree theory will be applied and an illustrative example will be considered to demonstrate the result.
The convergence properties of a new hybrid conjugate gradient parameter for unconstrained optimization models
Authors: Sulaiman I M , Mamat M , Waziri M Y , Yakubu U A , Malik M
Published: January 2021

The hybrid conjugate gradient (CG) algorithms are among the efficient modifications of the conjugate gradient methods. Some interesting features of the hybrid modifications include inherenting the nice convergence properties and efficient numerical performance of the existing CG methods. In this paper, we proposed a new hybrid CG algorithm that inherits the features of the Rivaie et al. (RMIL*) and Dai (RMIL+) conjugate gradient methods. The proposed algorithm generates a descent direction under the strong Wolfe line search conditions. Preliminary results on some benchmark problems reveal that the proposed method efficient and promising.
A robust energy policy review of selected African countries: An impetus for energy sustainability in Nigeria
Authors: Soyemi A O , Samuel I A , Adesanya A , Akinmeji A , Adenugba F
Published: January 2021

Power rationing has become the bane of the Nigerian power sector, plunging the nation into prolonged periods of darkness and costing about 2.5 percent of her GDP annually. Although, installed generating capacity is almost 13 GW, the situation worsened by an overdependence on thermal and hydro generation, high losses, and a poor tariff structure. In the face of these challenges, Nigeria seeks to achieve universal access by 2030 with sustainable power having a share of 30 per cent in her energy mix. Despite the existence of frameworks supporting this target, Nigeria’s policies are still weak; indicated by her low Regulatory Indicator for Sustainable Energy (RISE) score of 30. To reach universal access by 2030 and fulfil SDG 7; Nigeria needs the right mix of policies. This study aims to review, draw lessons from the successful and unsuccessful implementation of similar policies in five countries and give recommendations.
Design and implementation of a single phase to three phase rotary converter
Authors: Olowoleni J. O. , Awosope C. O. A. , Adoghe A. U. , Oguntosin V. , Okupevi E. S
Published: January 2021

Epileptic power supply, scarcity of fuel, and the ever increasing demand for power supply have given rise to the development of several off-grid and on-grid power alternatives. A single phase to three phase rotary phase converter is a machine that can generate three phase power supply from an existing single phase source. This is a cheap means of generating three phase power especially in some residential environments where access to three phase power is limited. Some home equipment such as air conditioners and refrigerators run on three phase power also workshop owners and technicians have need to operate three phase machinery which may include table saw, drilling machine, lathe machine, and any machinery that runs on three phase power.
Effect of distributed generation placement on power system: A case study of Eko electricity distribution company, LAGOS
Authors: Bango Owolabi P. , Agbetuyi A. F. , Samuel I. A. , Abdulkareem A. , Adoghe A. U
Published: January 2021

Protection coordination of distribution network has been one of the issues with the distributed generators integration. The reason is that the distribution network is radial in nature by which energy flow is unidirectional. The research aim is to investigate how the location or placement of DG affects the protection setting of the existing network. The healthiness of the test distribution system used in this work is investigated with and without DG connection by use of load flow analysis using Neplan software. The results confirm that the location or placement of DG with the distribution system connection improves the voltage profiles at each bus and active power load loss. The DG placed 1km away from point of common coupling (PCC), the voltage profiles is 10.448Kv with DG connection, and 10.442kV without DG connection, while active power load loss is 69kW with DG connection and 71kW without DG connection. Also, DG placed 6km away from point of common coupling the voltage profiles is 10. 404kV with DG connection 10.372Kv without DG connection, while the active power load loss is 110kW with DG connection and 131kW without DG is connected. Moreover, with the DG placed 1km away from the point of common coupling (PCC) the fault current 17.596kA with DG connection and 3.286kA without DG connection, while 6km away from the PCC is 17.543kA with DG connection and 3.286kA without DG connection. It can be concluded that as the distance of the DG from the PCC increases, the fault current also increases which affects the protection scheme of the existing distribution system.
Growth and characterization of copper cadmium sulphide thin films
Authors: Emegha J. O. , Damisa J. , Elete D. E. , Arijaje T. E. , Akinpelu A. , Ogundile P. O. , Onumejor C. A
Published: January 2021

Copper cadmium sulphide thin film was deposited onto glass (soda-lime) substrates using chemical bath deposition (CBD) technique at room temperature. Chemical, optical, structural, and microstructural features were examined via the Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), UV-Vis Spectroscopy, and High-resolution Transmission Electron Microscopy (HRTEM). FTIR revealed that the associated chemical bond was below the 900 cm-1 marks. The optical band-gap of 2.36 eV was estimated from the absorption analysis. X-ray diffraction measurements reveal that the deposited material is polycrystalline with hexagonal and cubic structures typical of the binary constituents of and thin films. The grain sizes were randomly distributed and ranged between 35 and 60 nm as indicated by the HRTEM.
Real Option Technique for an Assessment of the Itakpe Iron Ore Project
Authors: Amusan Adeola R. , Adinya Ini
Published: January 2021

This study examines the viability of an iron mining mineral with the approach of real options, which allows the mining project flexibility and scalability. A positive value for the Option to delay was achieved, which indicates the feasibility of the Itakpe project. In addition, the Option to abandon before the expiration of the project under unfavorable market conditions was obtained.
Solution of a barrier option Black-Scholes model based on projected differential transformation method
Authors: Edeki S. O. , Fadugba S. E.
Published: January 2021

In this article, the solution of the linear variant of a Barrier Option Black-Scholes Model (BOBSM) is considered via a semi-analytical approach referred to as the Projected Differential Transformation Method (PDTM). Similar to the traditional Differential Transformation Method, this new approach demonstrates feasible progress and efficiency of operation. For simplicity of illustrative, the BOBSM is converted to an equivalent heat-like form, and a series-form of the solution (root) is successfully obtained. Hence the PDTM is suggested for both pure and functional sciences for strongly nonlinear differential models with financial applications.
The influence of coffee cherry fermentation on the properties of Cascara arabica from Subang, West Java
Authors: Sholichah E , Desnilasari D , Subekti R J , Karim M A , Purwono B
Published: January 2021

Cascara is an infusion beverage of dried coffee cherry pulp prepared from a by-product of coffee production. Cherry of arabica coffee was fermented with spontaneous fermentation, Lactobacillus plantarum and yeast (Saccharomyces cerevisiae) at room temperature for 24 hrs. The properties of cascara including total phenolic, flavonoid, and caffeine contents, antioxidant activity, colour, and sensory acceptance were evaluated. Results showed that cascara from L. plantarum fermentation (Y) exhibited the highest polyphenols and caffeine contents of 46.78 ppm and 52.8 ppm, respectively. Cascara from spontaneous fermentation (X) resulted the highest flavonoids content and antioxidant activity of 0.28 ppm and 89.52%, respectively. The result of sensory evaluation showed that cascara from yeast fermented cherry obtained the highest overall acceptance score of 4 out of 6.
Pumpkin flour effects on antioxidant activity, texture, and sensory attributes of flat tubers noodle
Authors: Novita Indrianti N , Sholichah E , Afifah N
Published: January 2021

Canna and arrowroot are local tubers which have high amount of amylose content and suitable for noodle. Flat noodles are one type of noodles that are characterized with a thin flat shape and is generally made from starch. Pumpkin flour is one of the processed products of pumpkin fruit, which can be used in manufacturing of formulated foods as functional ingredient. The aim of this research was to study the effect of pumpkin flour on texture, antioxidant activity, and sensory attributes of flat tubers noodle. In this study, flat noodle was made from canna or arrowroot starch, which is added with pumpkin flour. We added the pumpkin flour (0%, 5%, 10%, and 15% w/w, canna or arrowroot starch basis) in the flat noodle formulation. Result showed that the addition of pumpkin flour increased antioxidant activity of flat tubers noodle. The stickiness of flat tubers noodle increased with the increasing of pumpkin flour level. Flat noodle made form arrowroot starch was stickier than flat canna noodle. Sensory analysis was carried out on flat canna noodle with hedonic scoring method to identify which product is the most preferred by the panelist. Generally the aroma and taste of flat canna noodle did not vary with increasing of pumpkin flours level. Flat noodle made from canna starch with 10% of pumpkin flour obtained the highest score for color, texture (stickiness), and overall acceptability assessed. Antioxidant activity and stickiness measurement of flat canna noodle with 10% of pumpkin flour were 39.80% and 3350 gf respectively.
Using kefir glucomannan to modify the diversity and composition of cecum bacterial in Sprague Dawley rats with metabolic syndrome
Authors: Desnilasari D , Harmayani E , Widada J , Nurliyani
Published: January 2021

This study aimed to determine the effect of kefir and kefir glucomannan (Kefir-GM) to the diversity and composition cecum bacteria and bodyweight and feed intake in rat metabolic syndrome. Research carried out used four group’s treatment, namely (1) control, normal rat (2) rats with metabolic syndrome (3) diet kefir in rats with metabolic syndrome, and (4) diet kefir-GM in rats with metabolic syndrome. After 4 weeks, cecum was taken for analysis of the diversity and composition of bacterial. Kefir and Kefir-GM in rats metabolic syndrome did not significantly affect the diversity at p<0.05, but increased Lactobacillus 14.61% and Bifidobacterium 2.2%, and decreased Clostridium 38.15% and Bacteroides 22.51%. Bodyweight and feed intake did not significantly different at p<0.05. Based on this research, kefir and Kefir-GM did not affect diversity but it is able to modify composition bacteria on cecum and also can keep the bodyweight and feed intake in rats.
Bio-modified soybean meal as a new protein source for food
Authors: Istiqomah L , Damayanti E , Suryani A E , Susilawati I O , Lutfiani
Published: January 2021

Soybean meal has long been considered as a plant protein source particularly for animal feedstuff. Nowadays, there is a promising prospect of this material for food processing. However, its protein utilization has drawbacks, such as poor protein solubility and anti-nutritional factors called phytic acid. The phytic acid could be reduced by the addition of phytase, whereas nutrient content enhanced by microbial fermentation. In this study, we analyzed the bio-modified of soybean meal (SBM) through fermentation by phytase producing Lactobacillus plantarum A1-E to evaluate its effect on nutritional quality and anti-nutrient factor called phytic acid and aflatoxin. The study was designated into two treatments consisted of unfermented soybean meal (USBM) and fermented soybean meal (FSBM) by L. plantarum A1-E. Parameters observed were microbial population, phytic acid content, aflatoxin content, and nutrient composition (moisture, ash, crude protein, crude fiber, and lipid). Data were analyzed using analysis of variance (ANOVA) and a T-test to compare treatment means. FSBM by L. plantarum A1-E increased population (6.8x107 CFU/ml) during 72 h incubation (P<0.05) than 0 h (2.1x106 CFU/ml). FSBM reduced phytic acid content (34.13%) and aflatoxin (6.12%) compared to control (USBM). Fermentation during 72 h had on average more crude protein (1.33-fold), crude fiber (2.09-fold), ash (1.13-fold), and less crude lipid (0.71-fold) than SBM. Thus, it can be concluded that FSBM by phytase producing L. plantarum A1-E could be applied for degradation phytic acid during food processing and represents an improvement in nutritional quality thereby becomes potential raw material as a new protein source for food.
Wastewater treatment based on remazol blue using DBD plasma reactor under acidic and basic conditions
Authors: Khairunizzahrah Badzlina , Bismo Setijo
Published: January 2021

Synthetic dyes are one of the most dangerous components of textile wastewater. Waste that contains various organic compounds, especially synthetic dyes, causes a high Chemical Oxygen Demand (COD) values. Remazol blue is a reactive dye that is widely used for the textile dyeing process. Therefore, water pollution occurs when the dye waste produced from textile activities is discharged into water bodies without prior treatment. In this study, innovation in waste treatment technology was applied in the Dielectric Barrier Discharge (DBD) plasma reactor. DBD are non-thermal plasma reactors designed to degrade organic and inorganic compounds in wastewater through oxidation process. This is carried out by active species, such as ozone (O3), hydrogen peroxide (H2O2) and hydroxyl radical (•OH), which are formed in the reactor. The study aims to evaluate the performance of non-thermal DBD plasma reactor in treating wastewater containing one of the textile dyes, namely remazol blue. The results showed that the percentage of degradation achieved was 98.43% within a process time of 120 minutes with a final concentration of 0.75mg/L. Furthermore, it showed that optimum conditions were obtained at pH value of 4, air flow rate of 2.5L/min, liquid flow rate of 50mL/min and a primary Neon sign transformer (NST) voltage of 19kV.