bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation study of CO2 laser-plasma interactions and self-modulated wakefield acceleration
Authors: Kumar Prabhat , Yu Kwangmin , Zgadzaj Rafal , Amorim Lígia Diana , Downer M. C. , Welch James , Litvinenko Vladimir N. , Vafaei-Najafabadi Navid , Samulyak Roman
Published: August 2019

3D numerical simulations of the interaction of a powerful CO2 laser with hydrogen jets demonstrating the role of ionization in the characteristics of induced wakes are presented. Simulations using SPACE, a parallel relativistic particle-in-cell code, are performed in support of the plasma wakefield accelerator experiments being conducted at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). A novelty of the SPACE code is its set of efficient atomic physics algorithms that compute ionization and recombination rates on the grid and transfer them to particles. The influence of ionization on the spectrum of the pump laser has been studied for a range of gas densities. Simulations reproduce both Stokes and antiStokes shifts in the spectrum of the pump laser, similar to those observed in experiments in the spectrum of the probe. Good agreement has been achieved with the experiments on the effect of variation in gas density on Stokes/antiStokes intensity. In addition, self-injection and trapping of electrons into the self-modulated wakes have been observed and analyzed. The experimentally validated code SPACE will be used for predictive simulations to guide future experiments at BNL ATF.
The Ir4+ substitution dependence of electric polarization as a probe of magnetic phase stability in multiferroic MnWO4
Authors: Wang H. W. , Zheng S. H. , Zhou G. Z. , Chen P. Z. , Lin L. , Yan Z. B. , Zhou X. H. , Jiang X. P. , Yu H. W. , Liu J.-M.
Published: August 2019

Hubnerite MnWO4 is a highly frustrated magnetic compound that has been known for its multiferroic properties. The intrinsic connection of ferroelectric polarization and magnetically frustrated structure allows an opportunity to probe the stability of magnetic structures against perturbations by means of measuring ferroelectric polarization. In this work, we investigate the ferroelectric polarization of Mn1 − 2xIrxWO4 to probe the stability of the low-temperature (T) collinear antiferromagnetic (AF1) phase against the Ir substitution, considering the strong spin-orbital coupling of Ir4+ that would enhance the single-ion anisotropy, on the one hand, and would favor the noncollinear spin alignment, on the other hand. Different from Mn1 − xRux/2WO4, it is suggested that the AF1 phase is only partially suppressed by the Ir substitution, allowing the emergence of the noncollinear antiferromagnetic (AF2) phase in coexistence with the collinear AF1 phase. Proper Ir substitution may promote both the magnetocrystalline anisotropy and the Dzyaloshinskii-Moriya interaction, thus making the modulation of the magnetic structure more complicated.
Enhancing optical transmission of multilayer composites using interfacial nanostructures
Authors: Chen Yi-An , Naidu Sharan V. , Luo Zhiren , Chang Chih-Hao
Published: August 2019

We demonstrate the suppression of light reflections at solid-solid interfaces in multilayer thin and thick films using interfacial nanostructures. The embedded nanostructures have subwavelength features and function as a gradient-index medium to eliminate Fresnel losses induced by refractive index mismatch between dissimilar materials. Suppressing the interfacial reflection can reduce interference effects in thin films, and the transmittance measurement of a polymer on a silica substrate demonstrates a two-fold decrease in interference fringe contrast. A thick multilayer composite consisting of three fused silica and two polymer layers has also been fabricated and demonstrates the enhancement of optical transmission up to 30% at high incident angles. The effects of the interfacial structure geometry are examined by theoretical models based on rigorous coupled-wave analysis methods. The experimental results agree well with simulation models, which predicts that further improvements can be achieved using the optimized tapered profile. This work indicates that interfacial nanostructures can improve the broadband and wide-angle response of multilayers and can find applications in thin-film optics, optoelectronic devices, and composite windows.
Quantum system-bath dynamics with quantum superposition sampling and coupled generalized coherent states
Authors: Bramley Oliver , Symonds Christopher , Shalashilin Dmitrii V.
Published: August 2019

Previously, we introduced two versions of the Multiconfigurational Ehrenfest (MCE) approach to high dimensional quantum dynamics. It has been shown that the first version, MCEv1, converges well to the existing benchmarks for high dimensional model systems. At the same time, it was found that the second version, MCEv2, had more difficulty converging in some regimes. As MCEv2 is particularly suited for direct dynamics, it is important to facilitate its convergence. This paper investigates an efficient method of basis set sampling, called Quantum Superposition Sampling (QSS), which dramatically improves the performance of the MCEv2 approach. QSS is tested on the spin-boson model, often used for modeling of open quantum systems. It is also shown that the quantum subsystem in the spin-boson model can be conveniently treated with the help of two level system coherent states. Generalized coherent states, which combine two level system coherent states for the description of the system and Gaussian coherent states for description of the bath, are introduced. Various forms of quantum equations of motion in the basis of generalized coherent states can be developed by analogy with known quantum dynamics equations in the basis of Gaussian coherent states; in particular, the multiconfigurational Ehrenfest method becomes a version of coupled generalized coherent states, and QSS can then be viewed as a generalization of a sampling method known for the existing coupled coherent states method which uses Gaussian coherent states.
Constructing dual-frequency OAM circular patch antenna using characteristic mode theory
Authors: Li Weiwen , Zhang Liangcai , Zhu Jianbin , Tao Ze , Liu Qing-Huo
Published: August 2019

The current wavemodes and their distribution features of the circular patch are analyzed by using the characteristic mode theory. Then, the corresponding characteristic modes are selected and the feed structure is designed to generate the vortex waves carrying orbital angular momentum (OAM), based on the idea that the OAM mode can be realized by combining two orthogonal degenerate modes. The experimental results show that the proposed antenna can effectively implement dual-frequency dual-mode OAM waves. The first-order OAM mode of the electric field component in beam axis z direction is realized at low frequencies, while the second-order OAM mode of the z-component field is obtained at high frequencies. The phase fluctuation of the OAM modes can be explained by the excitation coefficient of the characteristic mode with quantitative properties.
Epi-Gd2O3/AlGaN/GaN MOS HEMT on 150 mm Si wafer: A fully epitaxial system for high power application
Authors: Sarkar Ritam , Bhunia S. , Nag D. , Barik B. C. , Das Gupta K. , Saha D. , Ganguly S. , Laha Apurba , Lemettinen Jori , Kauppinen Christoffer , Kim Iurii , Suihkonen Sami , Gribisch Philipp , Osten Hans-Jörg
Published: August 2019

In this letter, we report the impact of epitaxial Gd2O3 on the electrical properties of an AlGaN/GaN high electron mobility transistor (HEMT) grown on a 150 mm diameter Si (111) substrate. Incorporation of epitaxial Gd2O3 grown by the molecular beam epitaxy technique under a metal gate (metal/Gd2O3/AlGaN/GaN) causes six orders of magnitude reduction in gate leakage current compared to metal/AlGaN/GaN HEMT. We observe that epi-Gd2O3 undergoes complete structural changes from hexagonal to monoclinic as the thickness of the layer is increased from 2.8 nm to 15 nm. Such structural transformation is found to have a strong impact on electrical properties whereby the gate leakage current reaches its minimum value when the oxide thickness is 2.8 nm. We find a similar trend in the density of interface traps (Dit) having a minimum value of 2.98 × 1012 cm−2 eV−1 for the epioxide layer of thickness 2.8 nm. Our measurements also confirm a significant increase in the two dimensional electron gas (2DEG) density (∼40%) at AlGaN/GaN interface with epioxide grown on AlGaN, thus confirming the contribution of epitaxial lattice strain on 2DEG modulation.
Long-duration direct drive hydrodynamics experiments on the National Ignition Facility: Platform development and numerical modeling with CHIC
Authors: Mailliet C. , Le Bel E. , Ceurvorst L. , Khan S. F. , Martinez D. , Goudal Th. , Izumi N. , Kalantar D. , Di Nicola P. , Di Nicola J. M. , Igumenshchev I. , Tikhonchuk V. T. , Remington B. , Smalyuk V. A. , Masse L. , Casner A.
Published: August 2019

We report on a novel planar direct-drive platform for hydrodynamics experiments on the National Ignition Facility (NIF). Its commissioning has been performed as part of the NIF Discovery Science Program. This platform enables the use of a 30 ns drive at an average intensity of 200 TW/cm2, creating a planar shock and ablation front over a 2 mm radius. To benchmark the performance of this design, the planarity of both the shock and ablation fronts has been measured between 26 ns and 28 ns after the start of the laser drive in a 3 mm-thick CH foil. The platform was then used to measure late-time Rayleigh-Taylor instability (RTI) growth at the ablation front for a 2D-rippled 300 μm-thick CH foil. Simultaneously, a numerical platform has been developed with the CHIC radiation hydrodynamics code at the CELIA laboratory. The CHIC numerical platform allows, for the first time, a complete simulation of the experiments over 30 ns to be performed. Large-scale simulations recover the trajectory and the 2D RTI growth measurements. They are further compared with half-mode simulations performed with identical parameters. We show that both numerical techniques fit with analytical modeling of RTI growth and discuss plans for future campaigns.
Formation of hot ice caused by carbon nanobrushes
Authors: Yagasaki Takuma , Yamasaki Masaru , Matsumoto Masakazu , Tanaka Hideki
Published: August 2019

Confinement in nanoscaled porous materials changes properties of water significantly. We perform molecular dynamics simulations of water in a model of a nanobrush made of carbon nanotubes. Water crystallizes into a novel structure called dtc in the nanobrush when (6,6) nanotubes are located in a triangular arrangement, and there is a space that can accommodate two layers of water molecules between the tubes. The mechanism of the solidification is analogous to formation of gas hydrates: hydrophobic molecules promote crystallization when their arrangement matches ordered structures of water. This is supported by a statistical mechanical calculation, which bears resemblance to the theory on the clathrate hydrate stability.
Dynamics of diffusiophoretic vesicle under external shear flow
Authors: Chuphal Prabha , P Varun , Thakur Snigdha
Published: August 2019

We investigate the dynamics of an active deformable particle in external shear flow. The active deformable particle under consideration is a diffusiophoretic vesicle that exhibits motility due to the asymmetric chemical reaction on its surface. The vesicle was constructed using the triangulated surface model, where a combination of chemically active and inactive vertices results in its propulsion. In most practical situations, the dynamics of active particles are affected by their environment and the external flow field is one such example. In this work, we observe the transition of vesicle dynamics from simple directed motion to a circular motion on application of shear flow, leading to a cycloidal trajectory. A detailed study about the dynamics of the active vesicle has been carried out here emphasizing the type of motion, shape, and tank-treading of the vesicle in shear. An elaborate comparison of active and passive vesicles has also been made.
Setup for simultaneous electrochemical and color impedance measurements of electrochromic films: Theory, assessment, and test measurement
Authors: Rojas-González Edgar A. , Niklasson Gunnar A.
Published: August 2019

Combined frequency-resolved techniques are suitable to study electrochromic (EC) materials. We present an experimental setup for simultaneous electrochemical and color impedance studies of EC systems in transmission mode and estimate its frequency-dependent uncertainty by measuring the background noise. We define the frequency-dependent variables that are relevant to the combined measurement scheme, and a special emphasis is given to the complex optical capacitance and the complex differential coloration efficiency, which provide the relation between the electrical and optical responses. Results of a test measurement on amorphous WO3 with LED light sources of peak wavelengths of 470, 530, and 810 nm are shown and discussed. In this case, the amplitude of the complex differential coloration efficiency presented a monotonous increase down to about 0.3 Hz and was close to a constant value for lower frequencies. We study the effect of the excitation voltage amplitude on the linearity of the electrical and optical responses for the case of amorphous WO3 at 2.6 V vs Li/Li+, where a trade-off should be made between the signal-to-noise ratio (SNR) of the optical signal and the linearity of the system. For the studied case, it was possible to increase the upper accessible frequency of the combined techniques (defined in this work as the upper threshold of the frequency region for which the SNR of the optical signal is greater than 5) from 11.2 Hz to 125.9 Hz while remaining in the linear regime with a tolerance of less than 5%.
Combining turbulence modelling techniques may address traditional limitations
Authors: Bandari Anashe
Published: August 2019

Researchers could bypass typical shortcomings in the modelling of turbulence by combining two approaches.
Mueller matrix metrology for measuring the critical dimensions of nanostructures
Authors: Kim Meeri
Published: August 2019

Mueller matrix metrology, an advanced ellipsometry technique, can be an effective tool for analyzing the critical dimensions of nanostructures.
iASPP mediates p53 selectivity through a modular mechanism fine-tuning DNA recognition
Authors: Chen Shuo , Wu Jiale , Zhong Shan , Li Yuntong , Zhang Ping , Ma Jingyi , Ren Jingshan , Tan Yun , Wang Yunhao , Au Kin Fai , Siebold Christian , Bond Gareth L. , Chen Zhu , Lu Min , Jones E. Yvonne , Lu Xin
Published: August 2019

The most frequently mutated protein in human cancer is p53, a transcription factor (TF) that regulates myriad genes instrumental in diverse cellular outcomes including growth arrest and cell death. Cell context-dependent p53 modulation is critical for this life-or-death balance, yet remains incompletely understood. Here we identify sequence signatures enriched in genomic p53-binding sites modulated by the transcription cofactor iASPP. Moreover, our p53–iASPP crystal structure reveals that iASPP displaces the p53 L1 loop—which mediates sequence-specific interactions with the signature-corresponding base—without perturbing other DNA-recognizing modules of the p53 DNA-binding domain. A TF commonly uses multiple structural modules to recognize its cognate DNA, and thus this mechanism of a cofactor fine-tuning TF–DNA interactions through targeting a particular module is likely widespread. Previously, all tumor suppressors and oncoproteins that associate with the p53 DNA-binding domain—except the oncogenic E6 from human papillomaviruses (HPVs)—structurally cluster at the DNA-binding site of p53, complicating drug design. By contrast, iASPP inhibits p53 through a distinct surface overlapping the E6 footprint, opening prospects for p53-targeting precision medicine to improve cancer therapy.
The changing agrarian economy in Zimbabwe, 15 years after the Fast Track Land Reform programme
Authors: Shonhe Toendepi
Published: August 2019

The reconfigured agrarian structure imposed new production and commoditisation patterns across the settlement types in Zimbabwe. From 2000, new markets were established, with differentiated effects on capital accumulation for different sets of farmers. After the Fast Track Land Reform programme, the impact of the economy-wide challenges, climate change, capital and global geo-politics on the agrarian economy remain relatively unexplored. Using a case study of Hwedza District, this article reveals the changing agrarian relations beyond the trimodal agrarian structure, showing that smallholder farmers have significantly relied on reinvestment of agricultural sales proceeds rather than contract farming. Farmers exit the contract farming arrangements citing their exploitative nature. The article contributes to the debate on Zimbabwe's agrarian and political transition.
The negotiability of state legal and bureaucratic authority during land occupations in Zimbabwe
Authors: Chamunogwa Arnold
Published: August 2019

The article explains how state legal and bureaucratic authority over land access was renegotiated, and at times undone, during land occupations in Mazowe District, Zimbabwe from 2001 to 2002. It explains the logics and strategies used by land occupiers to make use of legal and bureaucratic procedures, in contradictory ways, as they made, protected and validated claims to land and related resources. It also explains the ambiguous role of local state institutions during farm occupations. The author illustrates how certain state institutions adhered to long-standing technocratic ideas and practices of controlling land access, while others undermined and, at times, subverted them.
The fragility of empowerment: changing gender relations in a Zimbabwean resettlement area
Authors: Addison Lincoln
Published: August 2019

This article examines the fragility of women's empowerment in Sovelele, a resettlement area established through Zimbabwe's Fast Track Land Reform programme. Compared to their lives before resettlement, married women have larger plots allocated to them by husbands, exercise a higher degree of control over surplus grain and experience more joint use of resources. Single women can more easily buy and hold land in their own right. Yet, these gains are fragile because they arise out of largely unintended and changing circumstances, including the spatial dynamics of resettlement, permit-based land tenure, limited market integration and labour shortage. While attention to the conditions underlying empowerment reveals its fragility, it is not equally fragile for all women. Some women's gains may prove more resilient than others because they rest upon a deeper renegotiation of gender relations.
Enhancement of carotenoid biosynthesis in Phaffia rhodozyma PR106 under stress conditions
Authors: Zhang Jing , Li Qing-Ru , Zhang Ming-Hao , You Ying , Wang Yu , Wang Yu-Hua
Published: August 2019

Carotenoids have good biological activity in antioxidant, anti-aging and scavenging harmful free radicals. In this study, we screened a strain that produced carotenoids, and selected a stress condition which significantly improved carotenoids content. The strain was identified as Phaffia rhodozyma PR106. Active oxygen generator TiO2 was the most significant factor to the carotenoids content of the P. rhodozyma. The content of carotenoids was 54.45 mg/g at 500 mg/L TiO2, which was about 1.25 times of the control and the proportion of carotenoids also changed from 1:9:16 to 1:8.5:12. Further, we determined the reactive oxygen species (ROS) in YEPD medium and P. rhodozyma, found that the ROS (H2O2, O2−, and HO•) was significantly increased at 500 mg/L TiO2 in YEPD medium compared with the control, but increased in P. rhodozyma under 1000 mg/L TiO2 treated. These results suggested that the increase in carotenoids was related to ROS in P. rhodozyma.
Endothelial IQGAP1 regulates leukocyte transmigration by directing the LBRC to the site of diapedesis
Authors: Sullivan David P. , Dalal Prarthana J. , Jaulin Fanny , Sacks David B. , Kreitzer Geri , Muller William A.
Published: August 2019

Transendothelial migration (TEM) of leukocytes across the endothelium is critical for inflammation. In the endothelium, TEM requires the coordination of membrane movements and cytoskeletal interactions, including, prominently, recruitment of the lateral border recycling compartment (LBRC). The scaffold protein IQGAP1 was recently identified in a screen for LBRC-interacting proteins. Knockdown of endothelial IQGAP1 disrupted the directed movement of the LBRC and substantially reduced leukocyte TEM. Expression of truncated IQGAP1 constructs demonstrated that the calponin homology domain is required for IQGAP1 localization to endothelial borders and that the IQ domain, on the same IQGAP1 polypeptide, is required for its function in TEM. This is the first reported function of IQGAP1 requiring two domains to be present on the same polypeptide. Additionally, we show for the first time that IQGAP1 in the endothelium is required for efficient TEM in vivo. These findings reveal a novel function for IQGAP1 and demonstrate that IQGAP1 in endothelial cells facilitates TEM by directing the LBRC to the site of TEM.
Photoionization of tungsten ions: experiment and theory for W5+
Authors: Müller A , Schippers S , Hellhund J , Kilcoyne A L D , Phaneuf R A , McLaughlin B M
Published: August 2019

Experimental and theoretical cross sections are reported for single-photon single ionization of W5+ ions. Absolute measurements were conducted employing the photon–ion merged-beams technique. Detailed photon-energy scans were performed at (67 ± 10) meV resolution in the 20–160 eV range. In contrast to photoionization of tungsten ions in lower charge states, the cross section is dominated by narrow, densely-spaced resonances. Theoretical results were obtained from a Dirac–Coulomb R-matrix approach employing a basis set of 457 levels providing cross sections for photoionization of W5+ ions in the

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metastable excited levels. Considering the complexity of the electronic structure of tungsten ions in low charge states, the agreement between theory and experiment is satisfactory.
Gender bias on the students’ scheme in ratio and proportion solving problems
Authors: Setyaningsih Nining , Juniati Dwi , Suwarsono
Published: August 2019

The research aims to describe the gender bias on the student’s schema in ratio and proportion problem solving. The schema means to represent the student’s concepts stored in his or her memory and used for ratio and proportion problem solving. The research was conducted at SMP Muhammadiyah Program Khusus Junior High School in Surakarta, Indonesia. It employed a qualitative approach. The data were collected by interview and students’ written works. The subjects amounted to 2 male and female students with the similar high mathematical ability. The data were analyzed by using an interactive model, including data collection, data reduction, data presentation, and conclusions. The results of the research show that (1) the students’ schema in ratio and proportion problem solving comprised the content schema, the formal schema, and the linguistic schema; (2) the male subject with high mathematical ability (SLT) used the unit rate strategy, the cross product strategy, and the equivalent class strategy in ratio and proportion problem solving; and (3) the female subject with high mathematical ability (SLT) employed the equivalent strategy, the unit rate strategy, and the build up strategy in ratio and proportion problem solving. The different strategies in problem solving indicates varying schema in solving problems related to ratio and proportion.
Developing students’ collaboration skills through project-based learning in statistics
Authors: Desyarti Safarini TLS
Published: August 2019

In the era of Industrial Revolution 4.0, teachers are required to facilitate learning that provides opportunities for students to develop essential skills needed in the real working world. Employees need to perform strong collaboration skills to work productively on a team to accomplish complex assignments. Project Based Learning (PBL) is one of the learning models that give opportunities for students to develop collaboration skills. This study aims to describe how students’ collaboration skills develop through PBL in statistics. The design of learning activities and the rubric of collaboration skills were adopted from the 21st Century Learning Design (CLD) framework developed by SRI International in collaboration with Microsoft Partners in Learning (2012). In this study, students were carrying out the project with the theme “Statistics in School”. During the project, students were able to apply statistics concepts through data collection, data representation, and data analysis. The results of this study indicate that students’ collaboration skills have developed to level 5 of the 21st-CLD rubric. The following indicators were representing the results: students make substantive decisions based on group agreement, students take an important role in implementing the project, students work also depend on each other in order to complete the project.
Student’s critical thinking ability with higher order thinking skills (HOTS) question based on self-efficacy
Authors: Syarifah TJ , Usodo B , Riyadi
Published: August 2019

Critical thinking is one of the thinking abilities that must be given in 21st-century education, because by having it, the student can think reasonably, reflectively and systematically that carried out on all information or problems to make the right decisions. There are many factors that are affect students’ critical thinking ability, such as self-efficacy which has meaning selfconfidence, curiosity, and willingness to accept opinions, openness, independence, and decision making. This qualitative study aimed to describe students’ critical thinking abilities based on levels of self-efficacy by using the question of Higher Order Thinking Skills (HOTS). Purposive sampling technique has been used with 58 subjects with different levels of self-efficacy. Data collection was done using documentation, testing, and interview method. Showed student’s critical thinking ability on high self-efficacy is students can internalize the basic abilities of deep thinking, moderate self-efficacy students thinking ability are still systematic, and low selfefficacy student has limited insight. These results indicate that differences in self-efficacy will also make a difference in students’ critical thinking abilities.
Students’ mathematics learning achievement in junior high school using 7E learning cycle
Authors: Nur Rahmy Suci , Usodo B , Slamet I
Published: August 2019

The aims of this research are to determine the effect of applying the 7E learning cycle model and direct learning of students’ mathematics learning achievement. This research was conducted in several State Junior High School of Nganjuk Regency for academic year 2018/2019. The research method used the experimental method. The sample consisted of 184 students. The experimental class was given a 7E learning cycle model. The control class is given a direct learning model. This research used the documentation method and test method in data collection. Data analysis using a t-test, with a significance level of 5%. Data were obtained from the experimental class and the control class. The results of this research concluded that there were differences in the effect of 7E learning cycle implementation and direct learning on students’ mathematics achievement, and students’ mathematics learning achievement using the 7E learning cycle model was better than students using direct learning. The steps of the 7E learning cycle model such as for elicit, engage, explore, explain, elaborate, evaluate and extend can make students active in learning. To improve student’s mathematics learning achievement in junior high school can use the 7E learning cycle model.
Students’ responses to the test instruments on geometry reasoning ability in senior high school
Authors: Ayuningtyas Winanti , Mardiyana  , Pramudya I
Published: August 2019

This study aims to determine students’ responses to the geometry reasoning ability test instruments in high school. The research instrument used was the student response questionnaire to the test of geometrical reasoning ability. The study subjects took 28 students of grade XI. The data was obtained after the students having examined with the instrument test of geometrical reasoning ability. The research procedures include; first, the researcher gave the students questionnaire responses after they were asked to do a test of geometrical reasoning ability. Second, the researcher collected data obtained from the students’ response questionnaire. Third, the researchers conducted data analysis by calculating percentages to find out the number of student responses. Fourth, the researchers draw conclusions. The results of the analysis show that the students’ response to the geometry reasoning ability test instruments were very well. Most students show a positive response to the instrument, according to the language used in the instrument is easy to understand, the design of drawings and colors are interesting, and the materials used were adjusted to the level of ability of high school students.
Guided discovery: an alternative teaching method to reduce students’ rote learning behavior in studying geometric transformation
Authors: Ishartono Naufal , Nurcahyo Adi , Dwi Setyono Ikhsan
Published: August 2019

In Indonesia, geometry transformation is taught from elementary to high school students, but at the high school level geometric transformation material already has a high level of complexity that is already involved in the concept of matrices in the formula, especially the number of formulas that must be understood is very large, giving rise to the tendency of students to learn by memorization (rote learning). Of course, this matter cannot be underestimated by mathematics teachers so it needs a solution that can reduce the tendency of students to learn using the rote-learning method. Therefore, learning methods Guided Discovery can be seen as an alternative solution to be able to reduce the tendency of students to learn by memorization. This learning method can involve students actively to find and reconstruct formulas and concepts in the topic of transformation of geometry independently. Moreover, because they have studied the topic of geometry transformation at a previous level, they will use their prior knowledge to study it so that learning will be more meaningful. This research is a literature study where it aims to describe the possibility of applying Guided Discovery methods to reduce the tendency of students to learn geometry transformation topics in rote learning (rote learning behaviour). The results of this study are that theoretically by using Guided Discovery learning methods is possible to reduce the tendency of students to learn by memorizing in learning the topic of Geometry Transformation, namely the steps of Giving Problems, Data Developing, Data Arrangement, Extra Data, Verification, and Exercise.
Modelling the percentage of poverty based on an open unemployment rate using some nonparametric regression techniques
Authors: Andriyana Y , Suprijadi J , Suparman Y , Winarni S , Jaya I G N M
Published: August 2019

Poverty is a basic problem to be solved happened in all countries, including Indonesia. Although the economic development of Indonesia is increasing from time to time, but the population is also highly increasing. The population grows rapidly which is not followed by the same Gross Domestic Product development. The unbalance situation implies the gap of social-economic conditions. In order to reduce the poverty rate, we need to build a model showing the influence of some factors to the poverty rate. Since, the open unemployment rate plays an important role to the poverty rate, then in this study, we will focus only on modelling the open unemployment rate to the poverty in Indonesia. Due to the characteristic of the scatter plot of the data, where the pattern is not easy to model parametrically, we then propose some nonparametric regression techniques. We present some results using nonparametric approach, such as, kernel and splines techniques. For the kernel approach we propose to use Nadaraya-Watson technique and local polynomial approach, and for the spline techniques we propose to apply Smoothing Splines, B-Splines and P-Splines techniques. The estimation curves shows that all nonparametric approaches fit nicely to the data.
Business Process Analysis and Improvement for a Third Party Logistics Provider in Indonesian Cold Chain Logistics
Authors: Pradita S P , Ongkunaruk P
Published: August 2019

Indonesian consumer awareness to seek for quality fresh food products is increasing. Therefore, a cold chain logistics is required to deliver agricultural and fishery products across islands. The number of logistics providers in Indonesia are continuously growing, especially for cargo services. Our objectives are to identify the business processes and related activities in a cold chain logistics provider, to analyse problems and to provide recommendations for improvement. We conducted an in-depth interview and analysed the business process using Integration Definition for Function Modelling (IDEF0). The results showed that the major problems are lack of proper cold chain logistics and knowledge in supply chain management. Then, we recommended to improve efficiency in the major activities. These could be the direction for further development to enhance Indonesian cold chain logistics especially for other third party logistics providers to improve their competitive advantages.
Self-Assembly of Aldehyde Lipids in Water
Authors: Janlad M , Boonnoy P , Wong-ekkabut J
Published: August 2019

Lipid based self-assembled structures has been applied for drug delivery systems. It is well known that lipid self-assembled structures depend on the chemical structures of lipids, however the self-assembled structures of oxidized lipids with asymmetrical structures remain unclear. In this study, 1-palmitoyl-2-(9-oxo-nonanoyl)-sn-glycero-3-phosphocholine (9-al) was used to investigate its self-assembly structure. The molecular dynamics (MD) simulation was performed with the system consisting of 128 lipids and 8,960 simple point charge (SPC) water molecules. Initially, all lipids and water molecules were randomly generated in the simulation box, then molecular trajectories were integrated and collected over microsecond times. The results showed that the equilibrium self-assembled structures of 9-al lipid preferred to form a micelle structure. We analyzed the lipid’s angle distribution and the lipid’s chain length to determine the lipid geometry. The results are in agreement with the previous MD simulation (Boonnoy, P.; et al. J. Phys. Chem. Lett. 2015, 6, 4884 – 4888) that showed the deformation of aldehyde lipid bilayer into micelle structure due to their shorter and highly mobile of aldehyde functional group in oxidized chain.
Bond strength of laminated films between poly(lactic acid) based cast films and metalized cast polypropylene films
Authors: Hongsriphan N , Chaichana J , Pornpitakdamrong C , Thaptham S
Published: August 2019

This research was carried out to study the feasibility to use biodegradable poly(lactic acid) (PLA) in flexible packaging films, which they were usually laminated with metalized cast polypropylene (MCPP) film in order to reduce oxygen permeability and could be microwaveable. Since PLA was too brittle, two types of polymers; poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene glycol (PEG), were blended and extruded into cast films in the weight ratios of 5, 10, and 15 wt%. The prepared blend films were laminated with MCPP films using a commercial polyurethane adhesive. Mechanical and thermal properties of the blend films were investigated by tensile testing and differential scanning calorimetry. The bond strength of the laminated films was analyzed. It was found that the glass transition temperatures of PLA in the PLA/PEG blends were dramatically reduced attributed to the plasticizing effect, however, they were not changed in the PLA/PBAT blends. As a result, tensile strength of the PLA/PEG films was reduced significantly with respect to PEG content. The laminated films of PLA/PBAT blend and MCPP had higher bond strength than those of PLA and MCPP or PLA/PEG and MCPP. The transparent PLA/PBAT 95/5 wt% was the best formula that could replace poly(ethylene terephthalate) for laminated film.
Effect of Acetic Acid Pre-Treatment on the Growth Temperature of Graphene on Copper by Thermal Chemical Vapor Deposition
Authors: Kokmat P , Donnuea N , Nuntawong N , Wisitsoraat A , Ruammaitree A
Published: August 2019

Graphene is a flat monolayer of carbon atoms arranged in a honeycomb lattice. Graphene has many outstanding properties such as high electron mobility, superb strength, transparency and great flexibility. These exotic properties make graphene a promising candidate for solar cell, fuel cell, battery, supercapacitor and so on. In this report, we have studied the effect of acetic acid pre-treatment on the growth temperature of graphene on copper by thermal chemical vapor deposition (CVD). In case of graphene growth without acetic acid pre-treatment, the high temperature of 1000 °C is needed for the growth of graphene by CVD. In contrast, the growth temperature can be decreased to 800 °C for graphene growth with acetic acid pre-treatment. We found that acetic acid pre-treatment can eliminate copper oxide from the sample surface resulting in the growth temperature of graphene decreases.
Conductive paper of reduced graphene oxide and nanofibrillated cellulose
Authors: Tanpichai S , Aachri M , Pattananuwat P , Potiyaraj P
Published: August 2019

The conductive paper has been of great interest due to its flexibility and superior properties. In this work, the facile procedure with scalable possibility was used to prepare conductive paper with graphene oxide (GO) and reduced graphene oxide (rGO). GO synthesized by the modified Hummers’ method was successfully transformed to rGO using ascorbic acid. These GO and rGO were used as a conductive source to improve conductive properties of the as-prepared paper. GO and rGO (0 – 25 wt%) were mixed with nanofibrillated cellulose (NFC) to form conductive paper. Results showed that the reduction of the electrical resistance was found from both GO/NFC and rGO/NFC paper sheets with increasing a content of GO or rGO. Furthermore, the paper with rGO exhibited more outstanding electrical conductive than the GO/NFC paper. Also, the water uptake of the conductive paper was affected by the addition of GO or rGO. The significant reduction of water uptake was found to be more pronounced with the introduction of rGO in comparison with the presence of GO. The conductive paper prepared in this study would be useful for applications such as flexible electrode.
Study of the effect of electron beam on thermal and mechanical properties of poly(lactic acid)/poly(butylene succinate) blends
Authors: Tiptipakorn S , Hemvichain K , Pirombua A
Published: August 2019

In this research, the effect of radiation dose on thermal and mechanical properties of polymer blends between poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) were determined at the PLA/PBS weight ratios of 100/0, 80/20, and 0/100. Dicumyl peroxide (DCP) was used as additive at 0.2 phr. The radiation doses were varied at 0-150 kGy. There were some changes of chemical structure upon irradiation as observed via Fourier Transform Infrared Spectrometer (FT-IR), leading to the decrease of melting temperature (Tm) with the increase of radiation doses. Moreover, the flexural strength determined via Universal Testing Machine (UTM) were decreased with increasing radiation doses. The lowest biodegradation was found at the radiation dose of 50 kGy.
Potential Application of Biopolymer Chitosan and Cationic/Anionic Polymers in Textile Wastewater Treatment
Authors: Watcharin W , Wiratthikowit S
Published: August 2019

Biopolymer chitosan have been investigated for color removal in textile wastewater by using coagulation process of biopolymers and synthetic polymers. After the wastewater samples were treated with 0.1% chitosan for chitosan coagulation process, coagulation process of cationic or anionic polymer were performed by using chitosan and cationic polymer (CSC) or chitosan and anionic polymer (CSA) polymer concentrations of 0.1, 0.2 and 0.4 g/l at pH 6-8, respectively. The color removal efficiency of textile wastewater samples before and after treatment with chitosan followed by cationic/anionic polymers has been evaluated. The color removal by chitosan was dependent on pH and the maximum percent removal 31.4 ± 3.3% has been observed at pH 7. The optimum parameters for polymer-biopolymer coagulation process in this study was CSC at dosage of 0.2 g/l, pH 8 and CSA at dosage of 0.1 g/l, pH 7. Besides, its chemical analyses including Chemical Oxygen Demand (COD), dissolved solid, and suspended solid were analyzed in order to consider the potential application of chitosan in textile wastewater treatment. The results showed that the COD, dissolved solid and suspended solid of pre-treated textile wastewater were 290, 3998.7 and 280.7 mg/l, respectively, however, both dissolved solid and suspended solid were higher than the regulatory standard for wastewater. As the optimum condition, the COD, dissolved solid and suspended solid of textile wastewater after treatment with CSC (0.2 g/l at pH 8) were 260.7, 1939.8 and 103.6 mg/l, respectively, while the COD, dissolved solid and suspended solid of textile wastewater after treatment with CSA (0.1 g/l at pH 7) were 190.6, 3002.2and 106.8 mg/l, respectively. All of the results after treatments were within the regulatory standard. Therefore, the combination of chitosan and cationic/anionic polymers could be utilized in textile wastewater treatment.
Synthesis of sodium lignosulfonate from lignin extracted from oil palm empty fruit bunches by acid/alkaline treatment for reinforcement in natural rubber composites
Authors: Thungphotrakul N , Dittanet P , Loykulnunt S , Tanpichai S , Parpainainar P
Published: August 2019

This work studied a synthesis of sodium lignosulfonate (SLS) from the lignin which extracted from oil palm empty fruit bunches (OPEFB) by using batch method. The preparation of lignin from OPEFB was done by acid pretreatment using 1% (wt/wt) H2SO4 at 90 °C for 120 min in order to reduce hemicelluloses. Then lignin was extracted by 2.5% (wt/wt) NaOH at 90 °C for 180 min and precipitated by adjusting pH to 2 with 98% H2SO4. The obtained lignin was changed to SLS by using sodium bisulfite (NaHSO3). The study yields of prepared SLS conducted by varying concentration of NaHSO3. The obtained SLS was characterized by Fourier transform infrared spectroscopy and zeta potential compared to sodium lignosulfonate (commercial).
Effect of molecular weight of poly(L-lactic acid) on the stereocomplex formation between enantiomeric poly(lactic acid)s blendings
Authors: Srithep Y , Pholharn D , Akkaprasa T
Published: August 2019

The effect of molecular weight of poly(L-lactic acid) on the stereocomplex formation between poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) was investigated. Films of 1:1 blend were prepared from PLLA with molecular weight of 125, 180 and 209 kg/mol and PDLA with molecular weight of 150 kg/mol by a solution cast method. Thermal properties, crystalline structure and mechanical properties were measured by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD) and tensile testing. Blending lowest molecular weight PLLA (Mw 125 kg/mol) with PDLA showed highest stereocomplex formation with melting temperature more than 50°C compared to that of homocrystallites. As the molecular weight of PLLA became higher, the stereocomplex formation was lower. Films with higher stereocomplex formation also had higher mechanical properties.
Optimizationof poly(L-lactide)-polybutylene adipate terephthalate diblockcopolymer by ring opening polymerization
Authors: Pholharn D , Srithep Y
Published: August 2019

Polylactide (PLA) is a brittle biodegradable polymer: co-bonding of a higher flexibility polymer such as polybutylene adipate terephthalate (PBAT) into the PLA chains has been shown to make it more flexible. We studied the optimum conditions for synthesizing poly(L-lactide)-polybutylene adipate terephthalate diblock copolymer (PLLA-b-PBAT), with ratios by weight of L-lactide:PBAT from 100:0.3 to 100:1. Incubation times of polymerization were varied from 4 to 8 hours at 160°C. Nuclear magnetic resonance (NMR) spectra were used to verify the structure of synthesized polymers. Differential scanning calorimetry thermograms showed melting temperatures of diblock copolymers at around 161-168°C - characteristic of PLA. The optimum conditions for PLLA-b-PBAT synthesis by ring opening polymerization were 100:0.3 ratio and eight hour incubation leading to 95% yield, a high degree of crystallinity (71%) and the highest molecular weight (34,000g/mol, measured by gel permeation chromatography).
Solvated lithium ions in defective Prussian blue
Authors: Ruankaew N , Yoshida N , Phongphanphanee S
Published: August 2019

Prussian Blue (PB) or ferric hexacyanoferrate (II) is one of the most attractive materials in green battery industry. It has defective structure (d-PB),

Fe

4

III

[

Fe

II

(
CN
)

6

]

3

⋅

xH

2

O

(
x
≈
14
−
16
)

, that one of [Fe(CN)6]4− group is missing, and hydrated with water molecules at the 24e empty nitrogen site. In this study, we investigated the distributions of water and Li+ in d-PB by using three-dimensional reference interaction site-model (3D-RISM) theory, which is a statistical mechanics theory of molecular liquids. The theory can examine the selective ion adsorption in solvated molecular materials. The results from 3D-RISM show that there are 14 water molecules located in different positions inside the d-PB lattice, which are in good agreement with experiment. Moreover, we also found the Li+ distributed at inside d-PB lattice positioned closely to the 32f spherical cavity of d-PB.
Development of tyre tread compounds for good wet-grip : effects of rubber type
Authors: Suchiva K , Sirisinha C , Sae-oui P , Thapthong P
Published: August 2019

The present work reported the study of the effects of type of rubber on energy loss of tyre tread compounds for radial tyres which determines wet-grip properties of the tyres derived from them. The types of rubbers studied were solution SBR (S-SBR), emulsion SBR (E-SBR), functionalized S-SBR (FS-SBR), natural rubber (NR), functionalized NR (CNR), butadiene rubber (BR) and their selected blends.The wet-grip property was assessed by measuring tan δ at 0°C. It was found that FS-SBR gave tread compound with the best wet-grip property followed by S-SBR, CNR, E-SBR, NR and BR. Blends of SBR with lower ranking rubbers (CNR, NR and BR) also gave lower values of tan δ at 0°C or poorer wet-grip properties. The results can be explained by the viscoelastic properties of the rubbers and their interactions with silica.