bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rainfer: fertilizer production using rainwater as raw material
Authors: Zaman B , Handayani D S , Purwono  
Published: July 2021

Abstract
Shortly after the rain falls to the surface of the soil, the water flows into the water body or seeps into the ground without being optimally utilized. The low chemical and physical components are the main drawbacks of rainwater utilization. The raw material for fertilizer in this research is rainwater, so we call it rain fertilizer (rainfer). The main components of the additive are Bryophyta, sp, monosodium glutamate, hydrated lime, sodium chloride. They are added to enrich the physical and chemical components. The rainfer reactor is cylindrical with a maximum capacity of 70 liters. As much as 35 litres of rainwater plus additive is put into the reactor and stirred using a pump for 15 minutes until homogeneous. Let the mixture sit for 7 x 24 hours. The results showed that the addition of additives succeeded in increasing the parameters of TDS and conductivity respectively by 98.68% and 99.03%. The concentration of nitrate as nitrogen increased by 96.54%, from 1.13 mg/L to 32.67 mg/L. The final pH was 7.78, total P was 78.47 mg/L, total K was 0.03 mg/L, and heavy metal Cu was 0.06 mg/L. The level of toxicity based on the germination index value was 70.16% compared to the control, which is equivalent to mature and stable compost. The addition of additives can improve the quality of rainwater based on physical, chemical, and non-toxic parameters.
Probing the interaction of HAV4 peptide (Ac-SHAVAS-NH2) with E-cadherin domain EC1-EC2 by molecular docking
Authors: Aisyafalah S , Hudiyanti D , Asy’ari M , Siahaan P 
Published: July 2021

Abstract
E-cadherin-derived peptides, which are peptide sequences taken from their binding sites, have been shown to be able to modulate cross-cell junction so as to facilitate drug delivery to their targets. One of the E-cadherin-derived peptides, HAV4 (Ac-SHAVAS-NH2) previously has been studied by in vitro and in vivo where the activity of the HAV4 peptide is able to modulate the tight junction between E-cadherin cells. The physicochemical properties of macromolecule such as protein or peptide are very important to understand the function of the macromolecule. Computational chemistry method has good advantage for understanding physicochemical properties in studying the structure, dynamic, and interaction of molecules in support of experimental data. The purpose of this study is to prove the inhibitory activity of interaction between E-cadherin cells and the best conformation of HAV4 peptide by its binding energy and active site parameters. This study uses molecular dynamic simulation and molecular docking. The results of research in 27°C temperature at 20000 ps molecular dynamic simulation which prove the HAV4 peptide has the best conformation at the 2508 ps with conformation energy -47704.4 kJ.mol−1. Based on the results of molecular docking simulation, interaction between HAV4 peptide and E-cadherin domain EC1-EC2 show binding energy of -24.393 kJ.mol−1 with the Ki inhibition constant of 53.17 µM. This strong interaction occurs in the adhesion arm-acceptor pocket area with residual active sites Trp2, Ile4, Ile24, Lys25, Ser26, Asn27, Ser78, Glu89, Asp90, Met92.
Synthesis of chitosan-salicylaldehyde/vanillin Schiff base as antibacterial active compound on cotton fabrics
Authors: Ismiyarto  , Handayani W S , Ngadiwiyana  , Sarjono P R , Prasetya N B A 
Published: July 2021

Abstract
In this study, chitosan-salicylaldehyde/vanillin was synthesis by reflux method via condensation reaction. The aim of this study was to apply the Schiff base compound to cotton fabrics and test its antibacterial activity. The chitosan-salicylaldehyde/vanillin Schiff base was applied to cotton fabrics using spray method and antibacterial activity tested using turbidimetric method. The Schiff base was achieved with formation of brownish-yellow solids. The characterization of chitosan-salicylaldehyde Schiff base showed C=N vibration at 1649.18 cm−1, the ratio of Schiff base formed was 0.403 in a yield of 56% (b/b). The treated cotton fabrics using chitosan-salicylaldehyde/vanillin Schiff base showed optimum inhibition against Staphylococcus aureus up to 69% at 6 hours and Escherichia coli up to 7% at 18 hours.
Adsorption of Fe (III) metal ion by ionic imprinted polymer (IIP) method with poly (ethylene glycol) diglycidyl ether (PEGDE) as a crosslinker
Authors: Djunaidi M C , Fitriana W , Lusiana R A , Suseno A 
Published: July 2021

Abstract
The adsorption of Fe (III) metal ions in water media using the ionic imprinted polymer has been carried out with a polyeugenol base polymer and poly(ethylene glycol) diglycidyl ether (PEGDE) as the crosslinking agent. The adsorbent is in the form of Ionic Imprinted Polymer Fe (IIP-Fe), and Non-Imprinted Polymer (NIP) was also used as a comparison. The polymer results are characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), and Fourier Transform Infrared (FTIR). The adsorption test was performed to obtain the adsorption kinetics by varying the contact time. Meanwhile, adsorption isotherm was performed by varying the concentration of adsorbate, and adsorption selectivity between binary metal ions of Fe(III)/Cr(III), F(III)/Zn(II), and Fe(III)/Ag(I). Also, the adsorption mechanism was studied using different solvents such as HCl, Aquadest, KNO3, and Na2EDTA. The results of the filtrate in the adsorption test were characterized using AAS. The results showed the optimum time in kinetics was 60 minutes, the adsorption isotherm followed the Langmuir model with a large adsorption capacity of 23.640 mg/g on IIP-Fe and 17.636 mg/g on NIP. Adsorption selectivity towards Fe (III) metal ions in binary metal ions shows results in the order of Fe(III)/Zn(II)>Fe(III)/Cr(II)>Fe(III)/Ag(I), while the adsorption mechanism was dominated by hydrogen bonds.
Electrocoagulation and electro fenton and their applications in the processing of lindi water from landfill waste in campus area of Diponegoro University
Authors: Suhartana  , Pardoyo  
Published: July 2021

Abstract
Piles of garbage could an impact on reducing aesthethics, lowering the quality of groundwater and the health of the people who live around the landfill (TPA). The focus of research aims to reduce the content of organic pollutants dissolved in leachate at the Diponegoro University landfill (TPA). There are 2 methods chosen, namely the electrocoagulation method and the Fenton electro method. The electrodes used in these 2 methods are the same, namely aluminum and ferrous metals (as anode) and carbon (as cathodes). Our observations in the laboratory show that the dissolved organic matter in leachate at Diponegoro University’s final disposal site (TPA) (COD parameter) was 6.2 ppm, still far below the leachate content of TPA Jati barang 9.1 -16.2 ppm. The limit of the Government of the Republic of Indonesia in PP 82, 2001 (10 ppm). With the electrocoagulation method, when aluminum metal (as anode) was used, the amount of organic material that could be removed was 77.6%, while with ferrous metal (as anode) the amount of organic material that could be removed was smaller, namely 69.8%. Whereas with the Fenton electro method, when using aluminum metal (as anode), the amount of organic material that could be removed was 89.9%, while with ferrous metal (as anode) the amount of organic material that could be removed was smaller, namely 71.6%. The addition of inorganic salts (100 ppm NaCl and 100 ppm Na2SO4) was able to increase the yield of organic matter removal between 2.1 - 5.1%.
Analysis proximate of sargassum seaweed sp
Authors: Winarni S , Zainuri M , Endrawati H , Arifan F , Setyawan A , Wangi A P 
Published: July 2021

Abstract
Sargassum sp. seaweed becomes one of the interesting food preparations for the community and can be a potential local food-based product because this type of brown seaweed can be processed into food, pharmaceutical, cosmetic, and textile products. Seaweed Sargassum sp. has economic value and protection for marine life. Sargassum sp can be beneficial in the health field because it contains protein, minerals, alginates, active compounds of steroids, alkaloids, and phenols that function as antibacterial, antifungal, and antiviral properties. Sargassum sp., was the largest class of brown algae (Phaeophyta) in tropical seas. The purpose of this study was to determine the nutritional composition of Sargassum sp. which includes protein content, fat content, ash content, and water content. The method used is a proximate analysis method based on SNI 01-2354.4-2006, SNI 2891 01 1992, SNI 01-2354.1-2006, and SNI 2354.2: 2015. The results obtained were Sargassum sp protein levels of 3.048% higher than E. cottonii. Fat content in Sargassum sp of 0.617% of dry weight is lower than E. cottonii. The ash content of Sargassum sp was 7.112% higher than that of E. cottonii in proportion to the mineral content of the two seaweeds. The water content of Sargassum sp was 67.281% lower than E. cottonii, both of which were higher than the specified water content standard of <32%. This is also influenced by the drying process. Conclusion: Sargassum sp has good content to be consumed and used as local food products.
Effect different sampling times of Ulva sp on polysaccharide sulfate content
Authors: Sinurat E , Kusumawaty R , Fransiska D , Sihono  
Published: July 2021

Abstract
Ulva sp seaweed generally still harvested from nature, not cultivation. Therefore, guarantee to availability of its seaweed conducted storage in the warehouse. The purpose of this study was to determine the effect of sulfate polysaccharide content on the sampling times of Ulva sp. The sampling time of seaweed raw materials is freshly harvested seaweed, and other has been stored for 4 months. Dried Ulva sp and freshly Ulva sp obtained from Gunung Kidul. The testing parameters include ash content, polysaccharide content, sulfate content, and its yield. The results showed that the highest yield and total polysaccharides were obtained from freshly harvested seaweed, while the sulfate content was similar. Based on the polysaccharide extract test results obtained, storage affects the yield and it content of polysaccharides.
Synthesis of ferrate from ferrous sulfate using wet chemical approach and its application for remazol black B degradation: optimization and kinetic studies
Authors: Prasetya N B A , Suripto S J , Haris A , Ngadiwiyana  , Mohammed N S 
Published: July 2021

Abstract
Chemical oxidation is an effective method for treating wastewater that contains dyes. Ferrate is known as the strongest and environmentally friendly oxidizer in aqueous media. This study aims to degrade remazol black B dyes using ferrate synthesized by the wet chemical method from Ferrous ion of FeSO4.7H2O. This research studies the optimum conditions of degradation including pH, molar ratio and optimum time, degradation kinetics and the comparison of the effectiveness in degrading Remazol Black B dyes among ferrate to permanganate, peroxide and dichromate. The results show that ferrate can oxidize remazol black B effectively at an optimum pH 8, with a molar ratio of ferrates:dyes of 5:1 and the optimum time of degradation of 120 minutes, with the degradation percentage reaches up to 95%. The degradation kinetics of dyes follows first-order kinetics, and ferrate has the highest degradation effectiveness compared to permanganate, peroxide and dichromate.
Properties of the quantum vacuum calculated from its structure
Authors: Mainland G. B. , Mulligan Bernard 
Published: July 2021

Abstract
Physicists have speculated about the properties of the quantum vacuum for at least 85 years; however, only recently have they understood the quantum vacuum sufficiently well to begin making testable predictions. Specifically, using Maxwell’s equations to describe the interaction of the electromagnetic field with charged lepton - antilepton vacuum fluctuations, it has been possible to calculate the permittivity of the vacuum, the speed of light in the vacuum, and the fine structure constant. Physicists are now also beginning to successfully address problems in cosmology based on properties of the quantum vacuum. The terms “vacuum catastrophe” and “old cosmological problem” refer, respectively, to the predictions that the vacuum energy density and the cosmological constant are both approximately 120 orders of magnitude larger than the observed values. Using properties of the quantum vacuum and well-established physics, it is possible to demonstrate that the huge vacuum energy cannot transfer energy to normal matter; accordingly, vacuum energy contributes neither to the observed energy density of the universe nor to the cosmological constant, which plays a central role in the accelerating expansion of the universe.
Waves propagation through a localized axisymmetric vortical flow
Authors: Gadzhiev D A , Gaifullin A M 
Published: July 2021

Abstract
We propose a particular model for the axisymmetric vortex in two-dimensional space that can be generated under the rotation of the circular cylinder in a viscous fluid. The velocity field induced by such vortex is similar to the velocity field of the point vortex in the limited region and exponentially decays at infinity. We consider the plane acoustic wave propagation through such flow. The numerical solution for the scattered field is obtained using the exact integral representation. The scattered wave in the far field is an outgoing cylindrical wave peaking at small scattering angles.
Non-equilibrium dissociation and relaxation behind the shock wave within two-temperature approach
Authors: Gorbachev Yu , Kunova O , Shoev G , Bondar Ye 
Published: July 2021

Abstract
Within the recently proposed asymptotic method for solving the Boltzmann equation for chemically reacting gas mixture, the equations for a dissociating diatomic gas have been derived assuming two-temperature (translational-rotational + vibrational) approximation. Corresponding expressions for the reaction and relaxation rates, determined by the quasi-stationary vibrational distributions, have been obtained under assumption of dissociation from the highest vibrational level. Cut-off harmonic oscillator approximation for the diatomic molecules is assumed. It is shown that all reaction rates are the complex functions of the species densities. Analysis of a flow behind a shock wave is performed in a wide range of the flow parameters. It is shown that under strong non-equilibrium condition the dissociation rate is determined not by the dissociation probability, but by the vibration probability, since the excitation of highest vibrational levels is the bottleneck of dissociation process. This means that the procedure of obtaining the data on dissociation rates needs the accurate revision.
The influence of the emitting bodies surface boundary conditions on particle streams in their vicinity
Authors: Gunko Yu F , Gunko N A 
Published: July 2021

Abstract
The problem of the influence of boundary conditions on the surface of emitting bodies on particle flows in their vicinity is studied in this paper. The solution to this problem is actual and relevant both for studying the behavior of electron plasma in a closed space (diodes and multi-electrode devices) and in open space (studying electron flows in the vicinity of natural and artificial celestial bodies). This research is theoretical. The emitting particles are electrons. Moreover, it is assumed that the emission of electrons occurs in vacuum. The electric field potential on the surface of the emitting bodies is considered constant (the first boundary condition). The second condition is determined by setting the field strength on the body surface. Four types of boundary conditions are considered: 1) fully screened electric field; 2) mono-speed flow from the surface; 3) monoenergetic isotropic flow; 4) the starting particles are distributed according to the Maxwell’s law. In the second of the above cases, the desired dependence is found analytically. In the third and fourth cases, the dependences of the electric potential strength are found numerically using the kinetic approach. The calculation results are presented in the graphs.
Damped rotational vibrations of a long cylinder with a disk in the air flow
Authors: Kaufman D V , Ryabinin A N 
Published: July 2021

Abstract
We consider the drag and the damped rotational oscillations of a cylinder. The cylinder length-to-diameter ratio is nine. At the upstream end of the cylinder, a disk is mounted coaxially on the leg. The disk reduces the drag of the cylinder. The effect of the disk on damping of oscillations is described by aerodynamic rotational derivatives. Experiment in the wind tunnel is carried out with the flow past a cylinder fixed on an elastic spring suspension. In experiment, the diameter of the coaxial disk, position of axis of rotation and the gap between the disk and the cylinder vary. Deflected from the equilibrium position, the cylinder performs damped oscillations. The dependence of the amplitude of angular oscillations on time is determined by the tensometric method. Aerodynamic coefficients of rotational derivatives are found.
SD-effect for circular plates of lamina cribrosa and optic nerve
Authors: Pavilaynen Galina V , Franus Dmitry V 
Published: July 2021

Abstract
Asymptotic equations for stresses are presented and used for numerical modeling and graphical representation of elastoplastic properties of circular SD-plates. A numerical solution of the plate bend is obtained after calculating the system of fifth-order differential equations. Euler difference method and software package COMSOL 5.6 are applied to solve the problem for biological tissue.
Structural features of photogravitational celestial mechanics
Authors: Korolev V , Polyakhova E , Pototskaya I , Stepenko N , Tureshbaev A 
Published: July 2021

Abstract
The features of mathematical models of controlled motion of a spacecraft with a solar sail, which take into account the translational and rotational motion of all parts of the structure, are considered. Equations for motion in a photogravitational field are used on the basis of the two-body problem, taking into account perturbations, or a more general model of the bounded three-body problem. The gravitational field is supplemented by the field of light pressure forces, which makes it possible to simulate real dynamics processes. When approximating the system of equations of perturbed motion for different orbits and parameters of the main bodies, control capabilities and stability conditions of motion are obtained at the specified orbits, as well as in the vicinity of libration points. Stability of orientation or rotation relative to the center of mass is provided by the moment of light pressure forces on the elements of the sail system or additional actions of special engines.
Reduced description of local equilibrium monatomic oxygen flows with multiple ionization
Authors: Rydalevskaya M A , Shalamov I Y 
Published: July 2021

Abstract
A new scheme to describe ionized monatomic gases with multiple kinds of ions is suggested. The conservation equations of the momentum, energy, numbers of nuclei and electrons (both bound and free) are derived. Local equilibrium flows of dissociated ionized oxygen are considered. Temperature dependence of oxygen atoms, ions and free electrons concentrations is calculated for the case when the initial density of oxygen atoms is equal to the Loschmidt’s number. The dependence of pressure on temperature is also emphasized.
Physical and mathematical simulation of bridge segment oscillations
Authors: Shmigirilov R V , Ryabinin A N 
Published: July 2021

Abstract
On the basis of known mathematical models describing vibrations in the gas flow of a bluff body with one degree of freedom, a model of vibrations of a body with two degrees of freedom is obtained. The Krylov–Bogolyubov method is applied. Equations for slowly varying amplitudes and phase shift of vibrations are obtained. It turned out that the differential equations written for the squares of dimensionless amplitudes of translational and rotational vibrations coincide with the well-known Lotka-Volterra equations describing competition between two species of animals that eat the same food. In a wind tunnel, the change of modes of vibrations of the bridge segment predicted by a mathematical model is studied.
Nonlinear oscillation modes of spatial double pendulum
Authors: Smirnov A S , Smolnikov B A 
Published: July 2021

Abstract
The article studies nonlinear oscillations of a double mathematical pendulum which axes of the cylindrical joints are not collinear to each other and constitute an acute angle between themselves. Nonlinear oscillation modes of the system are constructed and analyzed in the first approximation using asymptotic methods. A quantitative verification of the obtained results is carried out by considering particular cases of a plane and orthogonal double pendulum and monitoring the energy integral in the appropriate approximation. The constructed analytical solutions are accompanied by graphic illustrations that clarify the essence of the solution.
On numerical bifurcation analysis of periodic motions of autonomous Hamiltonian systems with two degrees of freedom
Authors: Sukhov Egor 
Published: July 2021

Abstract
In this work we consider bifurcation problem for natural families of periodic motions of autonomous Hamiltonian systems with two degrees of freedom. While there exists a well-developed analytical approach to this problem, it is limited to small neighborhoods of known equilibria and stationary solutions. To explore the bifurcations of periodic motions for all admissible values of the problem’s parameters it is necessary to employ numerical methods. We propose an approach combining analytical and numerical computation of the natural families with numerical bifurcation analysis. We obtain the so-called base solutions either analytically or numerically for particular values of the problem’s parameters and then employ a numerical method to continue the base solutions to the borders of their existence domains and to identify bifurcation points. Linear orbital stability domains are also obtained in course of the continuation. To illustrate the proposed approach we analyze bifurcation of periodic motions emanating from Cylindrical precession of a dynamically-symmetric satellite on a circular orbit.
Local non-equilibrium phase density reconstruction with Grad and Chapman-Enskog methods
Authors: Timokhin Maksim , Rukhmakov Dmitry 
Published: July 2021

Abstract
The study of the non-equilibrium velocity gas distribution function reconstruction was carried out due to extended gas dynamics methods. The bimodal Mott-Smith solution for a plane shock wave was used as a reference distribution function. The shock-wave solutions were considered in the range of Mach numbers from Ma = 2.0 to Ma = 8.0. The reconstruction of the original function was carried out using the Navier-Stokes-Fourier, 13-moment, regularized 13-moment and 26-moment approximating functions.