bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Langmuir oscillations breaking driven by ion motion and relativistic effects
Authors: Pramanik Sourav , Maity Chandan 
Published: January 2021

Abstract
The nonlinear evolution of Langmuir oscillations (LOs) is studied in a cold plasma including the ion motion and (weakly) relativistic mass variation of electrons. For the purposes, a simple perturbation technique is used to solve the governing one-dimensional fluid-Maxwell’s equations. The solutions show that the Langmuir mode frequency acquires spatial dependencies due to the finite ion inertia and relativistic effects. As a result, excited LOs mix up in phase and break at arbitrarily low amplitudes. An approximate expression for the phase-mixing time of LOs is then obtained, thus improving some earlier results. Phase-mixing time is found to decrease with the increase of both the electron-to-ion mass ratio parameter and relativistic factor. A comparative analysis between these two effects is also carried out to clarify which effect contributes more to the phase-mixing time. It is revealed that phase-mixing is induced more quickly due to the ion motion than the relativistic effects.
Effect of resonant magnetic perturbations with plasma response on particle orbit characters
Authors: Su Chunyan , Chen Shaoyong , Mou Maolin , Guo Wenping , Chen Xieyu , Tang Changjian 
Published: January 2021

Abstract
The ion orbits considering the resonant magnetic perturbation (RMP) fields with plasma response are studied numerically using the full orbit code based on HL-2A tokamak parameters. The results show that RMP with plasma response can cause a more significant radial orbit expansion than the vacuum RMP field. Further study exhibits that the physical mechanism of the orbit expansion relates to the resonant field amplification (RFA) effect. The passing orbits expansion become quite large when ions pass through the region where the perturbed field is strongly amplified. Meanwhile, the trapped orbits expansion is determined by the average value of the perturbed field where corressponding orbit goes by. This indicates that the plasma response to RMP plays an important role in changing the characteristics of ion orbits, which can lead to a redistribution of fast ions and thus providing a possible mechanism for the degradation of plasma confinements in experiments.
A method for estimating masses ofWUrsaeMajoris-type binaries
Authors: Lu Li-Na , Liu Jin-Zhong , Jiang Deng-Kai , Wang Ya-Hui 
Published: January 2021

Abstract
Masses of W Ursae Majoris-type (W UMa) binaries play a critical role in investigating stellar dynamical evolutionary status. In this paper, we combine the PARSEC (PAdova and TRieste Stellar Evolution Code) with the Roche geometric model to provide a method to determine the masses of W UMa systems. To verify the validity of this method, we compile a sample of 140 spectrum binaries from the literature, which includes 76 W- and 64 A-subtype systems with reliable physical parameters. We find that the average fractional difference and the standard deviation (σM) of the residuals for W-subtype and A-subtype approximately amount to 15.66% and 0.1218, 16.03% and 0.2094, respectively. Meanwhile, we also perform detailed analyses in accordance with the orbital period, the effective temperatures and the mass ratio. We find that the method is more applicable to determine masses for W UMa systems with low effective temperature and short period.
The formation of a blue cluster in the local Universe
Authors: Wen Qing-Xin , Luo Yu , Kang Xi 
Published: January 2021

Abstract
It is well known from the Butcher-Oemler effect that galaxies in dense environment are mostly red with little star formation and the fraction of blue galaxies in galaxy groups/clusters also declines rapidly with redshifts. A recent work by Hashimoto et al. reported a local ‘blue cluster’ with a high fraction of blue galaxies (∼ 0.57), higher than the model predictions. They ascribed this blue cluster to the feeding of gas along a filamentary structure around the cluster. In this work we use group catalog from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and the state-of-art of semi-analytic model (SAM) to investigate the formation of blue clusters in the local Universe. In total, we find four blue clusters with halo mass ∼1014
M
⊙ at 0.02 < z < 0.082, while only the one found by Hashimoto et al. is in a filamentary structure. The SAM predicts that blue clusters have later formation time and most blue satellite galaxies are recently accreted. We conclude that the formation of blue clusters is mainly governed by newly accreted blue satellites, rather than the effect of large-scale environment.
Active Brownian particle in harmonic trap: exact computation of moments, and re-entrant transition
Authors: Chaudhuri Debasish , Dhar Abhishek 
Published: January 2021

Abstract
We consider an active Brownian particle in a d-dimensional harmonic trap, in the presence of translational diffusion. While the Fokker–Planck equation cannot in general be solved to obtain a closed form solution of the joint distribution of positions and orientations, as we show, it can be utilized to evaluate the exact time dependence of all moments, using a Laplace transform approach. We present an explicit calculation of several such moments at arbitrary times and their evolution to the steady state. In particular we compute the kurtosis of the displacement, a quantity which clearly shows the difference of the active steady state properties from the equilibrium Gaussian form. We find that it increases with activity to asymptotic saturation, but varies non-monotonically with the trap-stiffness, thereby capturing recently observed active-to-passive re-entrant behavior.
A computer system for the leukocytes classification in medical images
Authors: Chernykh E M , Mikhelev V M 
Published: January 2021

Abstract
The paper is about the development of a computer system for the white blood cells images classification. Solving the leukocytes classification task makes it possible to diagnose not only the blood diseases, but also a wide range of other diseases, as well as to evaluate the overall state of a person’s health. Modern leukocytes classification methods have a fairly large number of shortcomings, which make a problem of finding the most effective method as a tool to solve this task. In our computer system we use the method based on using a trained convolutional neural network as a binary classifier for the leukocytes classification. This study shows the advantages of using this architecture and a deep learning technology to solve the objects classification task in medical digital images. The developed system allows one, in most cases, correctly and with a high speed to determine whether the white blood cell belongs to one of the two classes, which indicates to the possibility of using this system as an auxiliary tool for the blood hematological analysis.
Uniqueness, existence and solution of the direct boundary heat exchange problem for a weakly non-linear temperature conductivity coefficient
Authors: Tanana V P , Markov B A 
Published: January 2021

Abstract
This work is a preliminary result necessary for the formulation and solution of the inverse heat conduction problem for a weakly quasilinear equation. Nevertheless, the article has independent significance. For the direct heat conduction problem a solution is constructed in the form of a series with a small parameter, the existence of the solution, its uniqueness are proved, and a number of estimates are made - in particular, the rate of decrease of the solution at large times. The solution is built for a medium, part of which has a piecewise constant coefficient of thermal conductivity, and part of the medium has slightly non-linear thermal diffusivity. The construction of a classical solution is impossible due to the discontinuity of the thermal diffusivity, therefore, on the sections of the media the matching conditions are set - the conditions for the continuity of the solution and the condition for the continuity of the heat flux. The solution to the weakly quasilinear equation is constructed in the explicit form of a series with a small parameter, for which uniform convergence is proved. The decreasing of the solution at large times is proved as of time raised to the negative third power.
Modeling Under Uncertainty: a Comparison of Approaches
Authors: Dobronets B S , Popova O A 
Published: January 2021

Abstract
A new approach to data processing and uncertainty modeling based on the use of computational probabilistic analysis is considered. The basis of computational probabilistic analysis is numerical operations on probability density functions represented by piecewise polynomial functions. The problems of predicting the time series of distributions and estimating the probability densities of solutions of boundary value problems and systems of nonlinear equations with random coefficients are considered. Interval analysis, functional data analysis, symbolic data analysis and Monte Carlo method are currently used to study such data. A comparison of these approaches is given. Numerical examples show the effectiveness of the proposed approaches.
Hybrid Hybrid one step trigonometrically scheme with oscillatory solutions for solving initial value problems of second order
Authors: Adeniran A. O. , Longe I. O 
Published: January 2021

Abstract
A hybrid one step scheme with coefficients based on the step size and frequency of the trigonometric function used as basis function is derived. The constructed scheme is use to solve some problems with oscillating solutions. Stability properties of the developed scheme was also discussed. Numerical result obtained through the implementation of the scheme show its computation efficiency and accuracy over some of the existing ones (Abhulimen and Okunuga[1], Adeniran, Odejide and Ogundare [2], Alabi, Oladipo and Adesanya[3], Awoyemi, Adebile, Adesanya, and Anake, [5]) in the literature.
On damping parameters of Levenberg-Marquardt algorithm for nonlinear least square problems
Authors: Umar A O , Sulaiman I M , Mamat M , Waziri M Y , Zamri N 
Published: January 2021

Abstract
The Levenberg-Marquardt (LM) algorithm is a widely used method for solving problems related to nonlinear least squares. The method depends on a nonlinear parameter μ known as self-scaling parameter that affects the performance of the algorithm. In this paper we examine the effect of various choice of parameters and of relaxing the line search. Numerical results obtained are used to compare the performance using standard test problems which show that the proposed alternatives are promising.
Numerical treatment of first order delay differential equations using extended block backward differentiation formulae
Authors: Chibuisi C. , Osu B. O. , Edeki S. O. , Akinlabi G. O. 
Published: January 2021

Abstract
In this research, we developed and implemented extended backward differentiation methods (formulae) in block forms for step numbers k = 2, 3 and 4 to evaluate numerical solutions for certain first-order differential equations of delay type, generally referred to as delay differential equations (DDEs), without the use of interpolation methods for estimating the delay term. The matrix inversion approach was applied to formulate the continuous composition of these block methods through linear multistep collocation method. The discrete schemes were established through the continuous composition for each step number, which evaluated the error constants, order, consistency, convergent and area of absolute equilibrium of these discrete schemes. The study of the absolute error results revealed that, as opposed to the exact solutions, the lower step number implemented with super futures points work better than the higher step numbers implemented with super future points.
Baeckea frutescen L. essential oil was tested with Aedes aegypti larvae at various concentration levels
Authors: Jemi Renhart , Simanullang Sumiati , Sarinah  , Nuwa  , Luhan Gimson , Koroh Desy Natalia 
Published: January 2021

Abstract
Reducing the negative impact of using synthetic insecticides in a friendly manner. The alternative is to use a bioinsecticide. Ujung Atap (Baeckea frutescens L.) essential oil is one of them that has the potential as a bioinsecticide. Distillation of fresh leaves and dry leaves. Aedes aegypti larvicide mortality test on the resulting essential oil. A. aegypti mosquitoes that cause dengue fever. Analyze the essential oil content of B. frutescens L. by GC-MS. The Dried Leaf Distillation of B. Frutescens L. produces more and better essential oil than fresh leaves. Dried leaf essential oil is more deadly against larvicides than fresh leaf essential oil of B. frutescens L. Larvacide activity is classified as toxic. There are 25 compounds found in essential oils of fresh leaves and 23 compounds in dry leaves. The compound which is a gastric poison for insects is Limonene.
Fermentation of amylolytic yeast and lactic acid bacteria to improve the quality of modified cassava
Authors: Damayanti Ema , Ichsyani Meylida , Istiqomah Lusty , Anggraeni Ayu Septi , Kurniadi Muhamad 
Published: January 2021

Abstract
The amylolytic activity has been studied in yeast and lactic acid bacteria (LAB) which are isolated from various types of traditional fermented cassava. The study aimed to obtain yeast and LAB isolates which high amylolytic activity for inoculum in cassava fermentation. A total of 23 yeasts and 22 LAB isolates were isolated from Gatot, Tiwul, Tapai, and Cassava fermented using chloramphenicol yeast glucose (CYG) media for yeast and de Man Rogosa Sharpe agar (MRSA) + CaCO3 for LAB. Yeast amylolytic activity was tested using yeast extract peptone starch agar medium, while the amylolytic LAB used MRS + starch media with Lugol’s iodine indicator. Colonies showing clear zone areas were measured as amylase activity on the iodine complex method. Isolates that have the highest amylolytic activity were used as inoculum in cassava fermentation. Yeast Tr7 and LAB G6 isolates showed the highest amylolytic activity (0.0624 U/mL and 0.0627 U/mL). Cassava fermentation products using yeast Tr7 and BAL G6 resulted 52.06% of hydrogen cyanide (HCN) reduction higher than without inoculum (32.32%). According to biochemical identification using API 50 CHL kit, LAB G6 isolate was 99.6% identical with Pediococcys pentosaceus whereas biochemical identification using API 20 C AUX showed that yeast Tr7 was 95.8% identical with Candida tropicalis. The biochemical identification result was similar to the molecular identification result. In molecular identification using 28S rRNA sequence analysis revealed that yeast Tr7 was 99% similar with Candida tropicalis NITCSK13 strain. LAB G6 was 100% similar with Pediococcus pentosaceus BSS1375 strain using 16S rRNA sequence analysis. C. tropicalis Tr7 and P. pentosaceus G6 potentially used for inoculum in cassava fermentation process to improve cassava quality as a functional food.
Cold water swelling starch: methods to prepare and recent applications
Authors: Sarifudin Achmat , Sholichah Enny , Setiaboma Woro , Tongta Sunanta 
Published: January 2021

Abstract
Cold water swelling starch (CWSS) offers advantage of unique properties over its origin. Among methods available to prepare CWSS, heating starch in ethanol can be considered to be the simplest one. The unique features of CWSS are depending on its starch origin and degree of conversion; therefore, its application should be specific depending on the feature of CWSS. This review summarizes methods to produce CWSS, advantage of producing CWSS by heating starch in ethanol method, the most important features of CWSS that influence its applicability, and exploration on CWSS applications. We expect that this review will be beneficial for food industries that utilize modified starch as ingredient in their products as well as researchers who seek potential applications of CWSS.
Metabolite Detection and Antibacterial Activity of Fungal Endophytic Extracts Isolated from Brotowali (Tinospora crispa) Plants using TLC-Bioautography Assay
Authors: Fathoni A , Hudiyono S. , Budianto E , Cahyana A H , Agusta A 
Published: January 2021

Abstract
Endophytic fungi may be a potent source of bioactive compounds and have a vast repertoire of diverse metabolites. One source of endophytic fungi host plants is a medicinal plant such as Brotowali or Tinospora crispa. Research corresponding to the antibacterial activity of endophytic fungi extracts isolated from T.crispa taken from several regions in West Java has never been reported yet. While antibacterial methods to evaluate their activity as well as to identify the chemical compounds is a TLC-bioautography assay. This research is aimed to investigate the components of endophytic fungal extracts and their antibacterial activity using the TLC-bioautography assay method. In this study, eighty isolates of endophytic fungi have been successfully isolated from plant tissues of T.crispa from several regions in West Java. Antibacterial activity by using TLC (dot-blot) plates revealed that the fungal extracts could inhibit S. aureus (77 extracts) and E. coli (35 extracts) with inhibition zones ranging from 8-30 mm. The endophytic fungi extracts that showed potent antibacterial activity against Gram-positive bacteria (S.aureus) were sixteen extracts, while nine extracts have good inhibition activity against Gram-negative bacteria (E.coli). Among the fungal extracts that have excellent ability against both Gram-positive and negative was namely TcBt1Bd-10 extract. Based on metabolites analysis using the TLC method, the possibility of the chemical compounds that played a role in antibacterial activity of the extracts, including phenolics, flavonoids, alkaloids, and terpenoids.
Candlenut oil encapsulation with Hidroxypropyl Methylcellulose (HPMC) for body lotion application
Authors: Yusri Silvya , Tiffany  , Sutanto Hery 
Published: January 2021

Abstract
Candlenut oil obtained by cold press extraction method was encapsulated in order to preserve the unsaturated fatty acids content from thermal oxidation. The encapsulation of candlenut oil was performed using hydroxypropil mrthylcellulose (HPMC) and maltodextrin as the encapsulating agent due to their filming ability. The solution of wall materials was added with the candlenut oil and emulsified, followed by spray drying process. Three different ratios of oil to wall materials (2:3, 1:1, and 3:2) were evaluated. Based on the peroxide values, encapsulation efficiency, wettability, and moisture content of the microcapsules, the sample with a ratio of 1:1 had better preservation ability towards candlenut oil and therefore used as the main ingredient for body lotion development. Three different concentrations of encapsulated candlenut oil (10%, 6%, and 2%) within the lotion base were observed and analyzed in terms of antioxidant activity by DPPH assay, and overall physical likeness. The result suggested that the wall materials might hinder the reaction between candlenut oil and DPPH radical compounds. The body lotion sample with the lowest content of encapsulated candlenut oil showed the highest antioxidant activity (IC50 = 52.31 ppm). Furthermore, according to the ANOVA test result, there was no significant difference in overall physical likeness between the three samples (p-value ≥ 0.05).
Characterization of Fine Particulate Matters Collected in the Vicinity of Coal-fired Power Plants in Java using ED-XRF
Authors: Lestiani D D , Santoso M , Kusmartini I , Atmodjo D P D , Kurniawati S , Sari D K 
Published: January 2021

Abstract
The number of coal-fired power plant in Java has been increased because of the government policy to supply the electricity in Indonesia to meet the electricity needs. This mega project is assumed to have an impact on the environmental and human health. In this study, the assessment of the air quality near the coal fired power plant has been carried out through characterization of the fine particulate matters. The particulate matters PM2.5 were collected in four sites in the vicinity of coal-fired power plant in Banten, West Java and Central Java, Indonesia. The elemental concentrations in PM2.5 such as Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb have been identified using energy dispersive X-ray Fluorescence-EDXRF. The validation of XRF measurement was applied using standard reference material NIST SRM 2783 Air Particulate on Filter Media. The elemental concentration of PM2.5 especially for the toxic elements as well as the mass and black carbon were compared between four sites. For some sites, the level of elemental concentrations was lower than other industrial sites in Java, due to the sampling was carried out before the commissioning/normal operation. Further and periodical monitoring will be needed to obtain a better comprehensive result to assess the impact of coal power plant to the surrounding environment.
The extraction of antioxidants from Chlorella vulgaris for cosmetics
Authors: Agustina Siti , Aidha Novi Nur , Oktarina Eva 
Published: January 2021

Abstract

Chlorella vulgaris is microalgae that contain chlorophyll as antioxidants, which has been widely used as a functional food. Antioxidants from Chlorella vulgaris also have potential as active ingredients in the cosmetics industry. Nowadays, consumers prefer natural cosmetics because they aren’t harmful to the skin. This study aimed to obtain chlorophyll antioxidants from Chlorella vulgaris and applied it to the cosmetics. The extraction process of antioxidants from Chlorella vulgaris was performed by maceration method, with Chlorella vulgaris concentration variable: 0.01; 0.05 and 0.1% in water as solvent. The antioxidant extracts powdered by spray drying method, with addition of 100 g/L maltodextrin. The observation was conducted on the characteristics of water content, ash content, carbohydrate content, protein content, antioxidant activity, and powder morphology. The extracts powder applied to cosmetics in the form of creams and lotions, then characterized for the antioxidant activity and microbial content. The best antioxidant capacity of extract powder was obtained on Chlorella vulgaris concentration 0.1%, which was 11.83 mg Vit C per 100 g sample. The results of antioxidant capacity in cosmetics as cream and lotion were 4.95 mg Vit. C per 100 g sample (IC50 719.75 mg/ml) and 4.73 mg Vit. C per 100 g sample (IC50 660 mg/ml), respectively. Both of cream and lotion weren’t shown any microbial contamination. Based on this study, Chlorella vulgaris with its antioxidant capacity can be developed as active ingredients for various kinds of cosmetics.
Magnetic convection in a nonuniformly rotating electrically conductive medium in an external spiral magnetic field
Authors: Kopp M I , Tur A V , Yanovsky V V 
Published: January 2021

Abstract
The research is devoted to the stability of convective flow in a nonuniformly rotating layer of an electrically conducting fluid in a spiral magnetic field. The stationary and oscillatory modes of magnetic convection are considered depending on the profile of the angular rotation velocity (Rossby number Ro) and on the profile of the external azimuthal magnetic field (magnetic Rossby number Rb). The non-linear dynamic system of Lorentz type equations is obtained by using the Galerkin method. Numerical analysis of these equations has shown the presence of chaotic behavior of convective flows. The criteria of the occurrence of chaotic movements are found. It depends on the parameters of convection: dimensionless numbers of Rayleigh Ra, Chandrasekhar Q, Taylor Ta, and external azimuthal magnetic field with the Rossby magnetic number Rb for Rayleigh (Ro = −1) and Kepler

(

Ro

=
−
3

/

4
)

profiles of the angular rotation velocity of the medium.