bluuebunny/crossref_metadata_2025 huggingface dataset:
A unified solution for the in-plane vibration analysis of multi-span curved Timoshenko beams with general elastic boundary and coupling conditions
Authors: Lv Xiuhai , Shi Dongyan , Wang Qingshan , Liang Qian
Published: October 2022

A unified solution for the in-plane vibration analysis of multi-span curved Timoshenko beams with general elastic boundary and coupling conditions by combining with the improved Fourier series method and Rayleigh-Ritz technique is presented in this paper. Under the current framework, regardless of boundary conditions, each of displacements and rotations of the curved Timoshenko beams is represented by the modified Fourier series consisting of a standard Fourier cosine series and several closed-form auxiliary functions introduced to ensure and accelerate the convergence of the series representation. All the expansion coefficients are determined by the Rayleigh-Ritz technique as the generalized coordinates. The convergence and accuracy of the present method are tested and validated by a lot of numerical examples for multi-span curved Timoshenko beams with various boundary restraints and general elastic coupling conditions. In contrast to most existing methods, the current method can be universally applicable to general boundary conditions and elastic coupling conditions without the need of making any change to the solution procedure.
Four field coupled dynamics for a micro resonant gas sensor
Authors: Liu Yulei , Qian Fengqiang , Xu Lizhong
Published: October 2022

In a micro resonant gas sensor, the electrostatic excitation is used widely. For a micro resonant gas sensor with electrostatic excitation, four physical fields are involved. In this paper, for the micro resonant gas sensor, the four-field coupled dynamics equation is proposed. It includes mechanical force field, chemical density field, electrostatic force field, and the van der Waals force field. Using the method of multiple scales, the coupled dynamics equation is resolved. The effects of the four physical fields on the natural frequencies for the micro resonant gas sensor are investigated. Results show that the effects of the Van der Waals force on the natural frequencies of the micro resonant gas sensor depend on the mechanical parameters and the bias voltages; the sensitivity of the natural frequencies to the gas adsorption depends on the mechanical parameters, the bias voltages, and the Van der Waals force.
The bonded macro fiber composite (MFC) and woven kenaf effect analyses on the micro energy harvester performance of kenaf plate using modal testing and Taguchi method
Authors: Hamdan A. , Mustapha F. , Ahmad K. A. , Mohd Rafie A. S. , Ishak M. R. , Ismail A. E.
Published: October 2022

The demand on wind energy application will continue to increase as fossil fuel prices keep increasing and the reservoir keeps decreasing. In wind energy, wind turbine application should be properly selected. The material selection for turbine blade fabrication is highlighted as well in recent research. For green material application, the usage of natural fiber reinforced composite, especially kenaf fiber, in the fabrication of wind turbines needs to be given due attention. Woven and unwoven kenaf fiber is employed to fabricate composite plates which replicate the simple turbine blade model. At the same time, Macro Fiber Composite (MFC) is attached to the kenaf plates for micro energy harvester purposes. There are two methods to attach the MFC used in this study which are surface bonded and embedding into the plate. In order to investigate the effects of bonding MFC technique, modal Testing analysis and Taguchi method is employed. It is found out that the damping percentage of both woven and unwoven kenaf plates increase at 100 % and 50 % respectively when bonded with MFC on their surfaces. Bonded technique is suggested as the most influenced factor in micro energy harvesting at the vibration range of 20 to 60 Hz. It summarized that, the kenaf woven type, the distance from structure neutral axis, the stiffness of structure, the excitation vibration and the neutral frequency of a structure are highlighted as the factors influencing the performance of micro energy harvester as well.
Real-time simulation dynamics model and solution algorithm for the trolley-hoisting system in container crane simulated training system
Authors: Lu Kai-liang , Mi Wei-jian , Jiang Ming-ming , Liu Yan-bang
Published: October 2022

The development of simulated training system (simulator) for container crane has made some progress; however, there are still problems in insufficient training function (e.g. the container spreader alignment skill training, one of the most important skill in conventional terminals) and lack of dynamic sense of immersion. In this paper, the technical status of container crane simulator is summarized and the state of art of dynamics model and its solution algorithm for container crane is reviewed. It is pointed out that establishing an accurate real-time simulation dynamics model and studying an efficient algorithm under certain calculation accuracy is the key problem of enhancing immersion, reality and training effect of the simulator. With reasonable simplification and hypothesis, the dynamic equilibrium equations of the trolley-hoisting system are established, further considering the characteristics of the mechanical and electrical transmission system of the crane and also the external mean wind load. Based on the four order Runge-Kutta method by MATLAB programming, the fast solution to the two order ordinary differential equations is realized on personal computer, and the three dimensional (3D) space swing time-history response of the container spreader can be obtained in real-time. The results of numerical calculation are consistent with the actual situation, thus, this study provides a feasible technical route for the real-time dynamics simulation in the container crane simulated training system.
Nonlinear vibration analysis of directional drill string considering effect of drilling mud and weight on bit
Authors: Taheran Farshad , Monfared Vahid , Daneshmand Saeed , Abedi Esmaeil
Published: October 2022

In this paper a nonlinear dynamic model for drill string in inclined well drilling is developed. Effects of drilling mud flow rate, weight on bit, angular velocity along with viscous damping on stability and vibration of the drill string are studied. Findings indicate the nonlinear effects are significant on the results. The effects of drilling mud flow rate and weight on bit on the natural frequencies and time responses are evaluated. Enhancement of drilling mud flow rate results in decreasing of natural frequencies and vibrational amplitude, while increasing the weight on bit, leads to decrease of the natural frequencies and increase the vibrational amplitude.
A high-throughput multi-hop WSN for structural health monitoring
Authors: Gao Shang , Yuan Shenfang , Qiu Lei , Ling Biyun , Ren Yuanqiang
Published: October 2022

Two major challenges with existing multi-hop WSNs used for structural health monitoring (SHM) are how to increase the data transmission rate (DTR) for large amounts of sampling data and enlarge the data transmission range without degrading link quality. To handle these issues, this paper proposes a new design method of a multi-hop WSN with multi-radio sink node (M-RSN) and double-radio relay node (D-RRN) which can increase the data transfer ability at the sink and extend the monitoring distance without degrading wireless link quality. Additionally, a tight scheduled approach and multi-radio time synchronization method are designed for the stable implementation of the proposed network. To evaluate the effectiveness and robustness of the proposed network designing method, experiments in outdoor environment and for aircraft composite wing boxes monitoring are carried out. The evaluation results have shown the advantages of the proposed methods.
Stability analysis and dynamic equilibrium of a Kuroshio generator system
Authors: Yu Hsing-Cheng , Chen Yi-An , Kehr Young-Zehr
Published: October 2022

Global resources for conventional energy are currently being exhausted, and several countries worldwide are attempting to develop renewable energy. Current generator systems are a subject of ocean power research. This paper proposes a novel design of a Kuroshio generator system (KGS) that is suitable for the maritime environment of Taiwan (i.e., an average flow velocity of the Kuroshio Current is 1.45 m/s and the flow can be accelerated on Keelung Sill with a depth of 50-250 m). The KGS combined a reliable cable design and simple anchor system at sea and was not affected by motion changes of rotation axes in yaw and roll by way of an appropriate rudder design. An intuitive simulation method applied using MapleSim software was used to create a rigid KGS model. Different modeling frameworks for varied cable design and joint positions were adjusted to meet system requirements. An intuitive simulation method applied using MapleSim software was used to create a rigid KGS model. Different modeling frameworks for varied cable design and joint positions were adjusted to meet system requirements. The stability analysis was performed to determine dynamic equilibrium and motion behavior of the KGS and the combined cable design. The optimal spring stiffness and damper coefficient of polyester fibers were set as 5×105 N/m and 3×105 N∙s/m in the simulation, respectively. Furthermore, to achieve the torque equilibrium in pitch motion of the KGS, an optimal joint position that was relative to the leading infraedge of the outer duct was set at 2.2 m along the negative surge axis according to their responses in the simulation. Finally, the force and torque generated by the hydrodynamic effect in the KGS and the estimated specifications of a direct-drive permanent magnet generator equipped with an external rotor were imported into the simulation. Consequently, the motion ranges of translation axes in surge and heave were converged within 0.5 m, and the estimated output power in the KGS exceeded 54.8 kW.
Seismic performance of reinforced concrete frames retrofitted with inserted steel frame and adhered waved steel panel
Authors: Ahn Namshik , Kim Min Sook , Song Seong-Eon , Lee Young Hak
Published: October 2022

In this paper, two types of seismic retrofitting methods for reinforced concrete frames were suggested and examined through the cyclic loading tests: one is to insert a steel frame to existing partially masonry infilled concrete frame of the building after removing masonry from the concrete frame and the other is to adhere waved steel panels to the existing masonry fully infilled concrete frame. In order to evaluate validity of the suggested methods in seismic performance, five specimens were manufactured and tested: a bare concrete frame, a partially masonry infilled concrete frame, a masonry infilled concrete frame, a steel frame inserted concrete frame, and a waved steel panel adhered concrete frame. Compared were crack pattern, failure mode, load-displacement relation, ductility, stiffness and energy dissipation capacity. The specimens retrofitted with the inserted steel frame showed a maximum load approximately twice that of the partially masonry infilled frame, and the specimen retrofitted with the adhered waved steel panel showed a maximum load approximately twice that of the masonry fully infilled frame.
Modeling of RC shear walls using shear spring and fiber elements for seismic performance assessment
Authors: Jeong Seong-Hoon , Jang Won-Seok
Published: October 2022

Reinforced concrete shear wall is one of the most effective members during severe lateral loads especially in earthquakes and winds. Extensive researches, both analytical and experimental, have been carried out to study the behavior of reinforced concrete (RC) shear walls. Predicting inelastic response of RC walls and wall systems requires accurate, effective, and robust analytical model that incorporate important material characteristics and behavioral response features. In this study, a modeling method using fiber and spring elements is developed to capture inelastic responses of an RC shear wall. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The parameters of the shear spring that represent strength and stiffness degradation, pinching, and slip are determined based on analysis results from a detailed finite element method (FEM) model. The reliability of the FEM analysis program is verified. The applicability of the proposed modeling method is investigated by performing inelastic dynamic analyses for reference buildings with various aspect ratios of shear walls.
Lift force, drag force, and tension response in vortex-induced vibration for marine risers under shear flow
Authors: Mao Liangjie , Liu Qingyou , Wang Guorong , Zhou Shouwei
Published: October 2022

An experiment was performed in a deep-water basin to investigate VIV mechanisms under shear flow. Lift force, drag force, and tension response were obtained. Results show that multiple frequencies are appeared for nonuniform vortex shedding frequency and interaction between the IL and CF vibrations. Beat phenomenon is observed in time history of lift force, and decreased with the increasing riser pretension. Dominant frequencies of riser tension are consistent with the IL and CF dominant frequency, and amplitudes of the tension are not uniform. VIV is inhibited with increasing riser pretension and the dominant frequencies also increase with increasing riser tension.
Dynamic behaviors of 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle
Authors: Sui Wenwen , Zhu Zhencai , Cao Guohua , Chen Guoan
Published: October 2022

Dynamic behaviors of the 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle is investigated. The telescopic mechanism is a combination of one vertical beam that can move axially, one constant beam perpendicularly fixed at the end of the vertical beam and one telescopic beam that can move along the axial direction of the constant beam during work. The Euler-Bernoulli beam theory is utilized to simplify the beams. The Lagrangian description is adopted to account for the coordinate for the telescopic mechanism. The equations of motion are derived using the Hamilton’s principle and decomposed into a set of ordinary differential equations by employing the Galerkin’s method. The eigenfunctions are acquired based on the boundary conditions by adopting the dichotomy method. The solutions to the equations are acquired using the Newmark-β method. Experiments are carried out to prove the validity of the theoretical model. Numerical examples are simulated to explore whether the vertical beam and telescopic beam can extend or retract synchronously and obtain appropriate beam moving strategy. The results prove that synchronous motion of the vertical beam and telescopic beam will not always lead to pronounced stronger vibration than the separate ones. On the other hand, the beam moving strategies that the telescopic beam moving before the vertical beam when they all extend out or retract back and moving after the vertical beam when one extends out and the other retracts back will effectively reduce the vibration compared with otherwise.
Effect of fractional-order PID controller with acceleration feedback on a linear single degree-of-freedom oscillator
Authors: Niu Jiangchuan , Shen Yongjun , Yang Shaopu , Li Xianghong
Published: October 2022

A linear single degree-of-freedom (SDOF) oscillator with fractional-order PID controller of acceleration feedback is investigated by the averaging method, and the approximately analytical solution is obtained. Moreover, the numerical solution of the system is obtained by the step-down order method and the power series method progressively. The effects of the parameters in fractional-order PID controller on the dynamical properties are characterized by some new equivalent parameters. The proportional component of fractional-order PID controller is characterized in the form of equivalent mass. The integral component of fractional-order PID controller is denoted in the form of the equivalent linear damping and equivalent mass. The differential component of fractional-order PID controller is denoted in the form of the equivalent linear negative damping and equivalent mass. Those equivalent parameters could distinctly illustrate the effects of the parameters in fractional PID controller on the dynamical response. A comparison between the analytical solution with the numerical results is made, and their satisfactory agreement verifies the correctness of the approximately analytical results. The effects of the parameters in fractional-order PID controller on control performance are further analyzed by some performance parameters of the time response. Finally, the robustness of the fractional-order PID controller based on acceleration feedback is demonstrated through the control of a SDOF quarter vehicle suspension model.
Study on failure warning of tool magazine and automatic tool changer
Authors: Chen Chuanhai , Tian Hailong , Zhang Jianhai , Shi Xiaohui , Chen Lei , Bao Jun , Duan Wei
Published: October 2022

Tool magazine and automatic tool changer (ATC) is used to store and change tools in a machining center, which plays an important role in automatic manufacturing. Therefore, the stability and reliability of tool magazine and ATC is very important to a machining center. Failures of tool magazine and ATC would increase ramp-up repair time and repair cost. So early warning system of failures for tool magazine and ATC becomes a research hotspot. The main vibration signals of tool magazine and ATC would occur obviously when the tool arm grasps a tool holder, draws a tool holder out of a tool into spindle or tool pocket and inserts a tool holder into spindle or tool pocket. To predict failures of tool magazine and ATC and improve the availability of machining center, a vibration test procedure and calculation method of vibration signal threshold of pull nails looseness which can lead to tool falling failures are proposed based on the vibration detection theory. Then, the vibration signals of tool changing are analyzed and the relationship between the maximum amplitude of vibration signals and the looseness severity of pull nails is also illustrated. The final experiment results show that the tool falling failure warning method is feasible to reduce the failures of tool magazine and ATC through the early warning system based on the threshold of vibration signals.
Structural performance experiment by moving cart to mount measurement sensors
Authors: Lee Eun-Taik , Eun Hee-Chang , Choi Young-Ji , Ahn Young-Jun , Lee Seung-Guk , Park Sang-Woo
Published: October 2022

The development of a measurement system for the purpose of structural performance evaluation has been needed. This work introduces a moving cart system on which to mount measurement sensors to measure acceleration and sound pressure in the time domain and an impact hammer for external excitation. The measurement data are utilized to evaluate the structural performance based on a mixed approach to directly and indirectly collect response data by a microphone and an accelerometer, respectively. The reliability of the measurement data is improved by the utilization of multiple sensors. The structural state is investigated by the power spectral density estimate (PSE) or proper orthogonal mode (POM) of the sound pressure and acceleration data. The applicability of the system is illustrated in a field test.
Dynamic performance analysis of nonlinear anti-resonance vibrating machine with the fluctuation of material mass
Authors: Li Xiaohao , Shen Tao
Published: October 2022

Aimed to solve the problem of weak anti-resonance performance and poor working stability in current anti-resonance vibrating machines, this paper presents a nonlinear dynamic model that reflects the actual working state of the anti-resonance machine. Under the material mass fluctuation condition, the dynamic response of the anti-resonance vibrating system has been discussed, and the dynamic parameters selection problem of the anti-resonance vibrating system has been analyzed which could be used to improve working performance stability. In the paper, the influence of nonlinear factors of the anti-resonance vibrating machine on the driving body and the working body has been analyzed under the material fluctuation conditions also. The results can provide the theoretical support and experimental basis for improving the design and working performance of the anti-resonance vibrating machine.
Effect of rolling process parameters on stability of rolling mill vibration with nonlinear friction
Authors: Zeng Lingqiang , Zang Yong , Gao Zhiying
Published: October 2022

Friction-induced vibration is a typical self-excited phenomenon in the rolling process. Since its important industrial relevance, a rolling mill vertical-torsional-horizontal coupled vibration model with the consideration of the nonlinear friction has been established by coupling the dynamic rolling process model and the rolling mill structural model. Based on this model, the system stability domain is determined according to Hurwitz algebraic criterion. Subsequently, the Hopf bifurcation types at different bifurcation points are judged. Finally, the influences of rolling process parameters on the system stability domain are analyzed in detail. The results show that the critical boundaries of vertical vibration modal, horizontal vibration modal and torsional vibration modal will move with the change of rolling process parameters, and the system stability domain will change simultaneously. Among the parameters, the reduction ratio has the most significant effect on the stability of the system. And when rolling the thin strip, the system stability domain may be only enclosed by the critical boundaries of vertical vibration modal and torsional vibration modal. In that case, the system instability induced by horizontal vibration modal would not occur. The study is helpful for proposing a reasonable rolling process planning to reduce the possibility of vibration, as well as selecting an optimal rolling process parameter to design a controller to control the rolling mill vibration.
A hybrid fault diagnosis method for mechanic-electronic-hydraulic control system based on simulated knowledge from virtual prototyping
Authors: He Deyu , Hu Niaoqing , Hu Lei
Published: October 2022

For the fault diagnosis of mechanic-electronic-hydraulic control system (MEHCS), the main barrier that restricts the application of knowledge-based methods is the lack of historical fault data. Aiming at this problem, this paper proposed a hybrid fault diagnosis method based on simulated knowledge from virtual prototyping. As a special form of mathematical model, virtual prototyping of MEHCS under faulty and nominal condition was established, validated, fault-injected and simulated to obtain simulation data. Fault features of different fault types were extracted, which were then trained by three pattern recognition methods to build the knowledge database for diagnosis. Threshold test and ensemble classifier constituted by the three pattern recognition methods were employed respectively to realize fault detection and isolation. To verify the proposed methodology, a case study of vessel steering system was presented. Fault types of stuck rudder and steady state error were studied. Probabilistic neural network (PNN), naive Bayes (NB), andk-nearest neighbor (kNN) were employed to constitute ensemble classifier based on majority voting. The diagnosis results showed that the accuracy of fault detection and isolation of both fault types were highly acceptable. The ensemble classifier performed better on comprehensiveness and smoothness than any individual pattern recognition method for the overall diagnosis. The proposed method might be an available choice for the fault diagnosis of MEHCS, especially for large-scale and complicated cases.
Damage detection of concrete piles subject to typical damages using piezoceramic based passive sensing approach
Authors: Feng Qian , Xiao Han , Kong Qingzhao , Liang Yabin , Song Gangbing
Published: October 2022

Pile foundations are typically comprised in concealed construction work. In recent years, some major categories of concrete piles subject to typical damages have caused a lot of engineering disasters and accidents. These accidents have been caused by collapse of civil structures resulting in great casualties and economic loss. Therefore, damage detection and real-time health monitoring on foundation piles is an urgent research requirement. In this research, a piezoceramic based passive sensing approach is proposed to detect typical damages types of concrete piles, including partial mud intrusion, secondary concrete pouring interface, circumferential crack, and full mud intrusion. In this passive sensing approach, induced stress waves are generated by the impact hammer on the top surface of a pile and one smart aggregate embedded on the bottom of each pile is used as a sensor to receive the propagating wave signals. These sensors are embedded before pouring concrete. Structural defects affect the natural frequency of the pile. The power spectrum of piles with different types of damage were compared by plotting the sensor signals in frequency domain. The natural frequency decreases with the increase in defect severity. The experimental results demonstrate that the proposed approach can detect all four typical damage types in concrete piles.
Micro-vibration isolation measurement platform using permanent magnet negative-stiffness devices and air springs
Authors: Zhang Xiaoping , He Lin
Published: October 2022

Environmental micro-vibration affects the accuracy of precision measurement devices. Passive isolation system can isolate most external vibration, decreasing its stiffness will improve isolation effect. Permanent magnet negative-stiffness device (PMNSD), which is mainly constructed from three permanent magnets, can decrease the system dynamic stiffness of isolation system without any effect to the static stiffness, when it is used parallel with positive-stiffness isolator. The mechanism of its negative stiffness is analyzed, and its stiffness is calculated by theory method and finite element method, it proves that the stiffness will decrease with the decrease of the initial air gap of magnets. A micro-vibration isolation platform using PMNSDs and air springs is constructed, it can carry many kinds of measurement instruments which weight 0-2000 Kg, keeping the system natural frequency under 1 Hz, it has good isolation capacity for micro-vibration over 2 Hz. The PMNSD will have greatly practical applications for its tunable negative stiffness, zero static stiffness, contact free, long life and so on.
Modeling and dynamic simulation on engraving process of rotating band into rifled barrel using three different numerical methods
Authors: Li Zhen , Ge Jianli , Yang Guolai , Tang Jun
Published: October 2022

The FEM (finite element method), FEM-SPH (smoothed particle hydrodynamics method) adaptive coupling method and the coupled Eulerian-Lagrangian method (CEL) are introduced to simulate the engraving process. Eight-node hexahedral elements were mainly used to build the finite element models of the rotating band engraving into the gun barrel except in CEL simulation. In this case, the rotating band model and mesh are both built in ABAQUS in order to meet the requirements of CEL simulation. The simulation results include the deformation process of the rotating band, the motions of the projectile, the dynamic engraving resistance and the calculating efficiency were obtained, compared and analyzed. The advantages and disadvantages of numerical methods when simulating engraving process are discussed. The results show that the FEM-SPH adaptive coupling method and the CEL method have advantages for applications involving the simulation of the engraving process. The intent is to better understand the numerical methods and eventually broaden the utilizations in analyses of interior ballistics.
Sound field separation technique using the principle of double layer patch acoustic radiation modes
Authors: Liang Guo , Haichao Zhu , Rongfu Mao , Junbo Su , Changwei Su
Published: October 2022

In order to solve the problems of near-field acoustic holography in applications such as external interference and aperture effects, a sound field separation technique using the principle of double layer patch acoustic radiation modes is proposed in this paper. The radiated acoustic pressures over two planar surfaces at certain distances from the sources are calculated first. Then, the effects resulting from the backscattering interference in non-free sound fields can be eliminated by a double-layer sound field separation technique. Next, data interpolation and extrapolation are performed on the separated data to increase the sound source's pressures on the holographic plane equivalently for holographic images with higher spatial resolution. Simulation and experimental results demonstrate that good agreements can be obtained with few measuring points.
Investigation of modal shapes of the alignment-leveling table
Authors: Kilikevicius Arturas , Cereska Audrius , Maskeliunas Rimas , Fursenko Antanas , Kilikeviciene Kristina , Sabaitis Deividas
Published: October 2022

This paper focuses on the assessment of modal forms of the alignment leveling table and their impact to the angle measurement accuracy of circular scales. It also addresses the impact of the experimental stand structure to the measurement of these scales. Even though the performed investigations are used to determine the precision of a specific angle measurement system, the findings do have a wider range of applications and can be used for the development of precision measurement instruments. Experimental and numerical investigations are used to illustrate the efficiency and effectiveness of the proposed alignment-leveling table.
effect of Tokopedia marketplace promotion on consumer shopping behavior in the COVID-19 pandemic
Authors: Liana Chendi , Haniza Nurul
Published: October 2022

The government's COVID-19 policy limits the actions of all Indonesians. People's buying habits have shifted to internet shopping via increasing marketplaces. This is why product-producing enterprises and MSMEs use the Marketplace. Markets use promotional methods to attract internet customers. The author wants to know how Tokopedia's marketplace promotion affected consumer shopping behavior during the COVID-19 epidemic. This research employs the Consumer Behavior Theory to investigate a consumer's decision-making process. This quantitative research employs linear regression analysis. Pesona Depok Estate dwelling RT 002 RW 022, Depok, was the study site and sample. Purposeful sampling. A predefined number of samples received a Google Form questionnaire. The coefficient of determination (R2) is 0.610, which suggests Tokopedia's marketing affected 61% of customer purchase behavior during the COVID-19 epidemic. Shopee's advertising affected customer purchase behavior during the COVID-19 epidemic.
Novel Antimalarial Drug Screening Based on Methyl Eugenol, Cinnamaldehyde, and Thiosemicarbazone with Cysteine Protease Inhibition: In Silico Molecular Docking, Molecular Dynamics, and ADMET Studies
Authors:   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Arianie Lucy , Eko Hermanto Feri ,   Biology Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Dhiaul Iftitah Elvina ,   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Warsito Warsito ,   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Widodo Nashi ,   Biology Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia
Published: October 2022

Plasmodium falciparum malaria contributes to significant global diseases. Computer-aided drug design, screening, and discovery were used to analyze a novel series of Methyl Eugenol Benzaldehyde Thiosemicarbazone (MEBThi) and Methyl Eugenol Cinnamaldehyde Thiosemicarbazone (MECThi) derivatives for malaria falciparum inhibition. This present study showed that 16 molecules from 28 of MEBThi and MECThi have affinities and interaction with active-site residues of cysteine protease, a key player in erythrocyte proliferation of P. falciparum. 13-MECThi demonstrates the best binding affinity at ˗8.0 kcal/mol while co-drug ˗5.6 kcal/mol. Physicochemical and pharmacokinetic assays of 13- MECThi have also revealed this potent compound. Toxicity analysis shows that 13-MECThi does not have mutagenicity and carcinogenicity characters, whereas co-drug has mutagenicity probability. The molecular dynamic evaluation illustrated that the 13-MECThi complex has higher Root Mean Square Deviation (RMSD) values, indicating its structure was more flexible than the chloroquine complex. Root Mean Square Fluctuation (RMSF) complex of receptor and 13-MECThi has no fundamental differences with chloroquine complex. This designed compound should be considered a falciparum antimalarial drug.
Anion Effect and Ligand Preference in the Precipitation of Ni(II) Complex from Methanolic Solution: Case of Tartrate vs Pyrazine
Authors:   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Finisia Yenni , Mutrofin Siti ,   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia, Ponco Prananto Yuniar ,   Chemistry Department, Faculty of Sciences, Universitas Brawijaya, Malang, 65145, Indonesia
Published: October 2022

This research aims to incorporate pyrazine in the synthesis of Ni(II)-tartrate-pyrazine metal organic frameworks or Ni(II)-T-P MOF as candidate of porous material. Synthesis of the targeted MOF was conducted at room temperature in a methanolic solution by mixing Ni(II) solution, L-tartaric acid (T), and pyrazine (P) solutions sequentially in various molar ratios (Ni(II):T:P = 1:1:0; 1:0:2; 1:2:2; and 1:2:4) using two different Ni(II) salts (chloride and nitrate). Solid products were characterized by infrared spectroscopy, qualitative anion identification test, melting point test, and scanning electron microscopy. The result shows that type of nickel salt affects the precipitation of Ni(II) complex, in which pale blue solids were precipitated out only from the chloride reactions (1:0:2, 1:2:2, and 1:2:4). IR and SEM analyses from the 1:2:2 and 1:2:4 reactions show identical result as also shown by the 1:0:2 reaction, whereas qualitative anion identification test result suggests that the chloride is uncoordinated to the Ni(II). The targeted Ni(II)-T-P is unsuccessfully obtained, instead the product is proposed to be [Ni(pyrazine)x(H2O)(6-x)]Cl2. although the tartaric acid was doubled and firstly reacted with the Ni(II), the pyrazine still has higher preference to coordinate to the Ni(II) center than the tartrate ligand.
Effect of Solvent Type and Germination Time on The Level of Free Amino Acid and Peptides of Germinated Pigeon Pea (Cajanus cajan (L.) Millsp) Extract
Authors:   Departement of Chemistry, Faculty of Mathematics & Natural Sciences, Udayana University, UNUD Campus Street, Jimbaran Bali, 80361, Indonesia, Ratnayani Ketut , Wisaniyasa Ni Wayan ,   Departement of Food Science & Technology, Faculty of Agricultural Technology, Udayana University, UNUD Campus Street, Jimbaran Bali, 80361, Indonesia., Wiwik Oktayuni Ni Putu ,   Departement of Chemistry, Faculty of Mathematics & Natural Sciences, Udayana University, UNUD Campus Street, Jimbaran Bali, 80361, Indonesia
Published: October 2022

Germination can activate the degradation of storage protein in legumes releasing peptides and free amino acids for seed growth. These compounds have many benefits in many fields, especially in food and health. This study aimed to determine the effect of solvent type and germination time on the level of free amino acids (FAA) and the level of peptides (MW < 10 kDa) of germinated pigeon pea extract. The extraction of free amino acids and the dissolved protein from germinated pigeon pea flour was carried out using two kinds of solvents, namely water, and 0.1 N HCl. The variation of germination times of pigeon pea seeds was carried out at 12, 24, 36, 48, 60, 72, 84, and 96 hours. The level of FAA was determined spectrophotometrically using the ninhydrin method after the deproteination step, while the level of peptides was determined spectrophotometrically using the biuret method. The results showed that using 0.1 N HCl as a solvent produced a higher level of FAA and peptides in the extract than using water. The increase of germination time can increase the level of FAA with the peak achieved in 36 hours. The increase of germination time can increase the level of peptides with the peak of peptides level achieved on 84 hours of germination. These results showed that seed germination is a potential method for producing free amino acids and peptides which accumulate at a specific time
Synthesis of Chitosan Magnetic Nanoparticles using Glutaraldehyde and Tripolyphosphate as Crosslinker
Authors:   Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Brawijaya Jl. Veteran Malang 65145, East Java, Indonesia, Alidha Rahmani Indri , Mulyasuryani Ani ,   Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Brawijaya Jl. Veteran Malang 65145, East Java, Indonesia, Andayani Ulfa ,   Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Brawijaya Jl. Veteran Malang 65145, East Java, Indonesia
Published: October 2022

Chitosan is an abundant natural polymer, which able to adsorb Pb2+. However, chitosan has the drawback of being unstable in acid and alkaline conditions, so it needs cross-linking. In this article, we will compare the usage of two crosslinkers, glutaraldehyde (GD) and tripolyphosphate (TPP), to solve these issues. The synthesis of chitosan magnetic nanoparticles was carried out by co-precipitation with the addition of glutaraldehyde under acidic conditions and the addition of TPP under alkaline conditions. The results showed that the FTIR spectrum gave characteristic bands at 3131.96 cm-1 (OH and NH), 1635.86 cm-1 (C=O), 1401.97 cm-1 (CN), ~1110 cm-1 (COC), and ~617 cm-1 (Fe-O). SEM analysis showed that the surface morphology of CMNP-GA particle aggregation was clear more than that of CMNP-TPP. The size of the synthesized nanoparticles was determined by PSA analysis, which was 131.95 µm and 137.10 µm, respectively. The results of the XRD analysis showed that, in addition to the Fe3O4 and chitosan phases, the produced CMNP also contained γFe2O3 phase, which was considered to be caused by Fe3O4 oxidation
Frequency of use of online assessment by higher level teachers during confinement due to the COVID-19 pandemic
Authors:   Instituto Politécnico Nacional, Escuela Superior de Cómputo, Mexico City, Mexico, Ruiz-Ledesma Elena Fabiola , Acosta-Gonzaga Elizabeth ,   Instituto Politécnico Nacional, UPIICSA, Mexico City, Mexico
Published: October 2022

The purpose of this research was to review how often mathematics teachers use technological tools to assess their students and, the relationship established with the reliability, ease of use, and usefulness that teachers find in them; in order to offer them courses or workshops that allow them to use different tools that help them in the evaluation process, as well as, to show them different options of use for the different moments in their class, such as in diagnostic, formative or summative assessment. Under the paradigm of quantitative research, a questionnaire was applied to a random sample of 12 teachers from a public institution of higher education in Mexico City. All teachers were invited (N=14), but only 12 were able to participate; therefore, there was an 8% margin of error. The application of the questionnaire was during the period of confinement. The reliability of the questionnaire has been validated and Pearson correlation analyzes have been carried out, based on the variables: frequency and ease of use, usefulness, and reliability. The results showed that in the category of medium use, more than half of the teachers in the sample have shown a frequency of regular use of the online assessment tools. A comparison was made with the authors of the reviewed literature and coincidences were found with the answers given by the teachers. For example, there are authors who showed that teachers use ICT more frequently in their classes when they have all the necessary technological skills. Due to the above, various alternatives were proposed that encourage teachers to use it. The higher the frequency of use of online platforms, the greater the utility they find in them. With the results obtained, it is concluded that the frequency of use of online platforms positively influences the development of confidence that teachers must work with these tools.
An Analysis of Individual Entrepreneurial Orientations in Predicting Malaysian Engineers’ Intention to Quit the Jobs using PLS-SEM Approach
Authors: Osman Idris , Mohd Hashim Maryam Jameelah , Mohd Idaya Husna , Kassim Suhailah , Othman Mohd Zailani , Mastor Suraya Hamimi
Published: October 2022

The objective of this study is to investigate the influence of individual entrepreneurial orientation (IEO) on the engineers' ITQ based on entrepreneurial orientation theory. The data were analysed using the Partial Least Squares-Structural Equation Modelling (PLS-SEM) to validate the research model and hypotheses. The findings reveal that the more IEO an organisation practices, the less likely its engineers' ITQ current jobs. Theoretically, this study extends the value of IEO components in predicting engineers' ITQ. Additional knowledge is required to incorporate the roles of IEO and engineers' behavioural expectations in order to address engineering talent shortages in a competitive labour market.
Keywords: individual entrepreneurial orientation; intention to quit; engineers; entrepreneurial orientation theory
eISSN: 2398-4287 © 2019. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open-access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under the responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians), and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.
DOI: https://doi.org/10.21834/ebpj.v7iSI8.3926
Possible Preventive Effect of Ziziphora clinopodioides Lam. Essential Oil on Some Neurodegenerative Disorders
Authors: Sahakyan Naira , Petrosyan Margarit
Published: October 2022

The present article describes some characteristics of the effect of essential oil (EO) extracted from Ziziphora clinopodioides harvested from Armenian highlands on microglial cell lines (BV-2 wild-type (WT) and acyl-CoA oxidase1 (ACOX1)-deficient (Acox1–/–) cells). The mutant cell line was used as a model to investigate cellular oxidative damage following EO treatment. The main components of the tested EO were pulegone, isomenthone, 1,8-cineole, piperitone, and neomenthole, with concentrations of 42.1%, 9.7%, 8.22%, 7.35%, and 5.9%, respectively, in plants harvested from the high-altitude Armenian landscape. The IC50 value of the EO in the DPPH assay was 7.025 uL/mL. The sub-cytotoxic concentrations (based on the MTT assay) for both cell lines were 5 × 10–1 uL/mL. The catalase activity of the WT cells was decreased following 24-h treatment with the EO, but that of Acox1–/– BV-2 cellswas increased. ACOX1 activity was decreased (up to 49%) at 72hof treatment. These results show the protective effect of the tested EO on Acox1–/– mutantcells.
Challenges and Problems on Self-directed Learning Readiness in Non–face-to-face Educational Settings During COVID-19
Authors: HEO JeongChul , HAN Sumi
Published: October 2022

This study aimed to verify whether self-directed learning readiness (SDLR) level can be significantly predicted by the literacy of learning management system (LLMS), motivation, and feedback interaction (FI) in non–face-to-face educational settings. We performed Pearson’s correlation analysis and multiple regression analysis. A total of 206 online college students responded to this web survey using simple random sampling. Results showed that three variables (LLMS, motivation, and FI) were positively associated with SDLR. Moreover, motivation and LLMS affected the SDLR level, and FI did not. Moreover, it is necessary for online educators to understand the problems that learners may face, such as low LLMS, low motivation, and lack of interaction in a non–face-to-face educational circumstances. In addition, this study suggested that they can encourage their students to increase LLMS and motivation for improving self-directed learning of online students during COVID-19 pandemic. Lastly, limitations and suggestions were discussed for future studies.
General Health Statuses as Indicators of Digital Inequality and the Moderating Effects of Age and Education: Cross-sectional Study
Authors: van Deursen Alexander J A M
Published: October 2022

Background

Considerable effort has been directed to offering online health information and services aimed at the general population. Such efforts potentially support people to obtain improved health outcomes. However, when health information and services are moved online, issues of equality need to be considered. In this study, we focus on the general population and take as a point of departure how health statuses (physical functioning, social functioning, mental health, perceived health, and physical pain) are linked to internet access (spanning internet attitude, material access, internet skills, and health-related internet use).

Objective

This study aims to reveal to what extent (1) internet access is important for online health outcomes, (2) different health statuses are important for obtaining internet access and outcomes, and (3) age and education moderate the contribution of health statuses to internet access.

Methods

A sequence of 2 online surveys drawing upon a sample collected in the Netherlands was used, and a data set with 1730 respondents over the age of 18 years was obtained.

Results

Internet attitude contributes positively to material access, internet skills, and health outcomes and negatively to health-related internet use. Material access contributes positively to internet skills and health-related internet use and outcomes. Internet skills contribute positively to health-related internet use and outcomes. Physical functioning contributes positively to internet attitude, material access, and internet skills but negatively to internet health use. Social functioning contributes negatively to internet attitude and positively to internet skills and internet health use. Mental health contributes positively to internet attitude and negatively to material access and internet health use. Perceived health positively contributes to material access, internet skills, and internet health use. Physical pain contributes positively to internet attitude and material access and indirectly to internet skills and internet health use. Finally, most contributions are moderated by age (<65 and ≥65 years) and education (low and high).

Conclusions

To make online health care attainable for the general population, interventions should focus simultaneously on internet attitude, material access, internet skills, and internet health use. However, issues of equality need to be considered. In this respect, digital inequality research benefits from considering health as a predictor of all 4 access stages. Furthermore, studies should go beyond single self-reported measures of health. Physical functioning, social functioning, mental health, perceived health, and physical pain all show unique contributions to the different internet access stages. Further complicating this issue, online health-related interventions for people with different health statuses should also consider age and the educational level of attainment.