bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of Jupiter Family Comet 252P/LINEAR During a Close Approach to Earth Reveal Large Abundances of Methanol and Ethane
Authors: Paganini L. , Camarca M. N. , Mumma M. J. , Faggi S. , Lippi M. , Villanueva G. L.
Published: August 2019

We observed short-period comet 252P/LINEAR post-perihelion during its 2016 passage, which presented a favorable opportunity to survey its chemical composition at a close Earth approach (∼0.14 au). We characterized the comet's chemical composition on four dates (UT 2016 April 12, 19, 26, and 29) using spectroscopic measurements with the Near-infrared Spectrograph (NIRSPEC) at the Keck Observatory on Maunakea, HI. Our high-resolution infrared spectra yielded production rates for four species (H2O, CH3OH, C2H6, and HCN) and upper limits for five species (NH3, H2CO, C2H2, CO, and CH4). We measured water at an average production rate of 4.9 ± 0.1 × 1027 molec s−1. The chemical properties of 252P suggest a rather typical composition, yet somewhat enriched in methanol and ethane but low in formaldehyde (upper limit) compared to other short-period comets surveyed at infrared wavelengths. Analysis of the ortho/para ratio in water indicates a nuclear spin temperature larger than ∼38 K, consistent with statistical equilibrium (2σ). Spatial distributions of gases, which are representative of possible heterogeneity in the nucleus and/or gas dynamics upon sublimation, showed rather symmetric profiles, with subtle enhancements of the more volatile species C2H6 and HCN toward the sunward hemisphere, while water showed spatial distributions that were extended toward the anti-sunward hemisphere. The continuum was characterized by a narrow distribution. We place our infrared results in the context of observations with the Discovery Channel Telescope, the James Clerk Maxwell submillimeter Telescope, and the Hubble Space Telescope.
Searching for Highly Magnified Stars at Cosmological Distances: Discovery of a Redshift 0.94 Blue Supergiant in Archival Images of the Galaxy Cluster MACS J0416.1-2403
Authors: Chen Wenlei , Kelly Patrick L. , Diego Jose M. , Oguri Masamune , Williams Liliya L. R. , Zitrin Adi , Treu Tommaso L. , Smith Nathan , Broadhurst Thomas J. , Kaiser Nick , Foley Ryan J. , Filippenko Alexei V. , Salo Laura , Hjorth Jens , Selsing Jonatan
Published: August 2019

Individual highly magnified stars have been recently discovered at lookback times of more than half the age of the universe, in lensed galaxies that straddle the critical curves of massive galaxy clusters. Having established their detectability, it is now important to carry out systematic searches for them in order to establish their frequency, and in turn learn about the statistical properties of high-redshift stars and of the granularity of matter in the foreground deflector. Here we report the discovery of a highly magnified star at redshift z = 0.94 in a strongly lensed arc behind a Hubble Frontier Field (HFF) galaxy cluster, MACS J0416.1-2403, discovered as part of a systematic archival search. The bright transient (dubbed “Warhol”) was discovered in Hubble Space Telescope data taken on 2014 September 15 and 16. The point source faded over a period of two weeks, and observations taken on 2014 September 1 show that the duration of the microlensing event was at most four weeks in total. The magnified stellar image that exhibited the microlensing peak may also exhibit slow changes over a period of years at a level consistent with that expected for microlensing by the stars responsible for the intracluster light of the cluster. Optical and infrared observations taken near peak brightness can be fit by a stellar spectrum with moderate host-galaxy extinction. A blue supergiant matches the measured spectral energy distribution near peak, implying a temporary magnification of at least several thousand. The short timescale of the event and the estimated effective temperature indicate that the lensed source is an extremely magnified star. Finally, we detect the expected counterimage of the background lensed star at an offset by ∼0.″1 in a deep coaddition of HFF imaging.
Fine-structure Excitation of Ne+ in Collision with Atomic Hydrogen
Authors: Wan Yier , Leiberman P. , Buenker R. , Loch S. D. , Schultz D. R. , Stancil P. C.
Published: August 2019

Fine-structure line emission from [Ne ii] is observed in the infrared (12.81 μm) and could serve as a diagnostic of X-ray irradiation in protoplanetary disks. [Ne ii] emission may also trace the disk gas and indicate the presence of shocks due to outflows. As the electron fraction decreases with decreasing height from the plane of a disk, collisions with atomic hydrogen begin to play an important role in populating excited fine-structure levels. We present computations of cross sections for fine-structure excitation in collisions of

with atomic hydrogen using a fully quantal molecular-orbital close-coupling approach with complete angular momentum coupling. The results are based on accurate calculations of NeH+ molecular potentials obtained from the multireference single- and double-excitation configuration interaction method. We find that the excitation cross sections are dominated by resonances at energies below 1000 cm−1. Quenching rate coefficients are given at temperatures (10–2000 K) of astronomical interest and compared with the electron impact rate.
Cosmic-ray Spectrum Steepening in Supernova Remnants. I. Loss-free Self-similar Solution
Authors: Malkov M. A. , Aharonian F. A.
Published: August 2019

The direct measurements of cosmic rays (CRs), after correction for the propagation effects in the interstellar medium, indicate that their source spectra are likely to be significantly steeper than the canonical E
−2 spectrum predicted by the standard diffusive shock acceleration (DSA) mechanism. The DSA has long been held responsible for the production of galactic CRs in supernova remnant (SNR) shocks. The γ-ray “probes” of the acceleration spectra of CRs on the spot, inside the SNRs, lead to the same conclusion. We show that the steep acceleration spectrum can be attributed to the combination of (i) spherical expansion, (ii) tilting of the magnetic field along the shock surface, and (iii) shock deceleration. Because of (i) and (ii), the DSA is efficient only on two “polar caps” of a spherical shock where the local magnetic field is within ≃45° to its normal. The shock-produced spectrum observed edge-on steepens with the particle energy because the number of freshly accelerated particles with lower energies continually adds up to a growing acceleration region. We demonstrate the steepening effect by obtaining an exact self-similar solution for the particle acceleration at an expanding shock surface with an arbitrary energy dependence of particle diffusivity κ. We show that its increase toward higher energy steepens the spectrum, which deeply contrasts with the standard DSA spectrum where κ cancels out.
The Factors of Affect Indoor Air Quality Inpatient at Private Hospital, Pekanbaru, Indonesia
Authors: Rahayu Endang Purnawati , Saam Zulfan , Sukendi Sukendi , Afandi Dedi
Published: August 2019

BACKGROUND: Air quality in inpatient rooms influenced by several factors. Room not qualified health can cause disease and can spread through equipment, the material used, food and drink, health workers, patients and visitors.
AIM: The purpose of this study is to know the factors that affect air quality in the inpatient room at a private hospital, Pekanbaru.
METHODS: The research is quantitative analytic by design cut latitude study. Samples from 120 nurses were selected overall sampling. The data do with the measurement directly, interviews and observation using a questionnaire. Data analysed by using the chi-square with significance p-value less than 0.05.
RESULTS: The quality of the air in inpatient rooms has met the standard. Variables are affecting air quality in inpatient rooms in the hospital significantly with p-value more than 0.05 is temperature, dust, the germ, density occupancy, sanitation room. While the moisture, standard operating procedures and behaviour is not significant.
CONCLUSION: The factors that significantly affect indoor air quality inpatient hospitalisation are temperature, dust, germ numbers, occupancy density, room sanitation.
Correlation between Estrogen Levels with Lipid Profile in Menopause Women in West Sumatera
Authors: Ariadi Ariadi , Jamsari Jamsari , Yanwirasti Yanwirasti , Siregar Muhammad Fidel Ganis , Yusrawati Yusrawati
Published: August 2019

BACKGROUND: Menopause is a condition where women had not experienced menstruation for 12 consecutive cycles. At menopause period, there is alteration in women reproductive cycle where estrogen decreased and lipid status altered.
AIM: This study is aimed to understand the association of estrogen level and lipid status in menopause women.
METHODS: This study was an observational study with cross-sectional design underwent in Obstetrics and Gynecology Polyclinic Dr M. Djamil Hospital, Padang to examine estrogen level and lipid level in 107 menopause women aged between 40-60 years old. The study was conducted for 6 months. The relationship between estrogen level and lipid profile was done using correlation test and p-value < 0.05 is significant.
RESULTS: There was no significant correlation between estrogen and total cholesterol (p = 0.146), LDL (p = 0.496), HDL (p = 0.172) and triglyceride (p = 0.296) in menopause women. There was negative correlation between estrogen with total cholesterol (r = -0.141; p = 0.146), HDL (r = -0.133; p = 0.172) and triglyceride (r = -0.1; p = 0.296) and a little positive correlation with LDL (r = 0.06; p = 0.496). Estrogen levels are not related to total Cholesterol, LDL, HDL, and triglyceride in menopause women
CONCLUSION: Estrogen levels did not correlate with lipid status in menopause women in West Sumatera.
Natural history collections as a basis for sound biodiversity assessments: Plexauridae (Octocorallia, Holaxonia) of the Naturalis CANCAP and Tyro Mauritania II expeditions
Authors: Sampaio Íris , Carreiro-Silva Marina , Freiwald André , Menezes Gui , Grasshoff Manfred
Published: August 2019

Mapping biodiversity is the marathon of the 21stCentury as an answer to the present extinction crisis. A century in which science is also characterised by large scientific datasets collected through new technologies aiming to fill gaps in our knowledge of species distributions. However, most species records rely on observations that are not linked to specimens, which does not allow verification of species hypotheses by other scientists. Natural history museums form a verifiable source of biodiversity records which were made by taxonomists. Nonetheless, these museums seem to be forgotten by biologists in scientific fields other than taxonomy or systematics. Naturalis Biodiversity Center (NBC) in Leiden is care keeper of large collections of marine organisms, which were sampled in the Northeast Atlantic during the CANCAP andTyroMauritania II expeditions (1976–1988). Many octocorals were sampled and deposited in the NBC collection, where they became available for study and were partially identified by the senior author (M.G.) in the 1980s. Nonetheless, no checklist or taxonomic revision was published so far with the complete results. In 2016 the first author visited NBC to examine NE Atlantic Plexauridae octocorals. Plexauridae octocoral-vouchered records were listed and mapped to reveal high standard primary biodiversity records unreported so far for the NE Atlantic Ocean. Twenty-four Plexauridae species with ~ six putative new species to science were discovered and eleven new biogeographical records were made from distinct Macaronesian archipelagos. Finally, new depth range records were found for three species at sea basin level and for eight species at a regional scale.
La communication sur la Responsabilité Sociale de l’Entreprise : défi de pertinence et enjeu de la perception des parties prenantes. Proposition d’un cadre conceptuel d’analyse
Authors: Tioumagneng André
Published: August 2019

Le débat sur la Responsabilité Sociale de l’Entreprise (RSE) met en exergue un consensus sur l’insatisfaction de la demande d’information qu’en expriment les parties prenantes. Il donne à voir qu’une explication du problème réside dans la focalisation des entreprises sur la communication écrite. Cet article se propose de montrer l’intérêt de transcender la traditionnelle rhétorique écrite, par l’expérimentation de la communication verbale en l’occurrence, et de voir l’entreprise comme un lieu de production de discours multiforme. L’approche est conceptuelle et procède de l’appréhension de la RSE comme un objet complexe. Elle met en dialogue trois référentiels théoriques touchant aux comportements stratégiques des entreprises face à la complexité, aux pratiques langagières des entreprises et à la lecture d’inspiration socio-économique de l’entreprise. La portée du travail est pragmatique, autant pour l’entreprise que pour ses partenaires, et les pistes de recherche qu’il ouvre sont relatives notamment au silence organisationnel dans la communication et au pilotage des outils de gestion sur la RSE.
Vers une éthique de la robotique
Authors: Boyer André , Farzaneh Faranak
Published: August 2019

Depuis leur apparition au milieu du XX e siècle dans le domaine industriel, les robots se développent dans de nombreux secteurs économiques, autour de l’utilisation de l’intelligence artificielle (IA). Dans cette communication, après avoir examiné ce que signifie aujourd’hui la notion de robot, nous analysons les questions éthiques qu’engendre la robotique dans divers secteurs de la société, à commencer par l’industrie, en passant par la robotique militaire et policière, la santé, l’éducation, les robots ménagers et en terminant par l’agriculture et l’environnement. À partir de cette analyse, nous recherchons un cadre éthique pour la robotique, dont nous essayons de définir une problématique à partir du couple « action et responsabilité » des robots.
Quid de la GRH dans la PME : une analyse à partir de la vision stratégique des propriétaires-dirigeants des PME camerounaises
Authors: Tchatchoua Thierry , Tsapi Victor , Djeumene Paul
Published: August 2019

L’objectif de cet article est d’analyser la place de la GRH dans la PME à partir de la vision stratégique des propriétaires-dirigeants des PME camerounaises. À l’aide de la méthode de la cartographie cognitive, il ressort de cette étude que la gestion des ressources humaines occupe une place prépondérante dans la vision stratégique des propriétaires-dirigeants de ces entreprises. En effet, les concepts centraux les plus importants de leur carte cognitive font référence à une gestion de ressources humaines paternaliste comme condition sine qua none pour la réalisation des objectifs de croissance de ces propriétaires-dirigeants.
École nationaliste et interculturalité. Les cas du Mexique et Chili depuis la voix des enseignants indigènes
Authors: González G Jaime A. , Berríos V Adolfo
Published: August 2019

L’article propose une évaluation de l’école nationaliste au Mexique et Chili. La recherche s’appuie sur une méthodologie d’étude de cas qui repose sur l’enregistrement de deux témoignages oraux des enseignantes indigènes de chaque pays. Les séquences scolaires étudiées révèlent les dommages psychologiques engendrés par la politique d’aliénation symbolique qui ne respecte pas la diversité culturelle. Bien que la principale réussite de l’école nationaliste se trouve dans l’habilitation sociale qui engendre l’instruction chez les sujets, son principal défaut est l’homogénéisation forcée dans collectives humaines plurielles. Pour faire de l’éducation interculturelle un outil de transformation sociale, il est nécessaire d’incorporer cette discussion dans la formation initiale d’enseignant. Depuis une perspective critique, l’interculturalité doit contribuer à questionner le tissu social que l’école nationaliste a contribué à bâtir, en identifiant les facteurs que restreint son passage vers un projet de société.
Memorias, enseñanza de la historia y democratización en escuelas de Buenos Aires y Bogotá
Authors: Higuera Rubio Diego
Published: August 2019

L’auteur fait une révision de quelques concepts autour de la mémoire sociale. Cette révision a pour but d’évaluer l’importance du concept de mémoire sociale et le lien qu’établissent les nouvelles générations avec son passé récent. Indiscutablement, nous voulons mettre en valeur l’importance des contenus d’histoire dans ce processus. D’abord, nous avons repris les propos de Michel Pollak et Maurice Halbwachs, car ils sont pertinents lors du travail de transmission de la mémoire dans les sociétés où les individus transitent par divers espaces de socialisation. Ensuite, nous avons analysé des entretiens effectués à des jeunes et adolescents de quelques collèges et lycées de Buenos Aires et de Bogota. Ce travail permet de donner de la valeur aux concepts déjà exposés. Finalement, nous faisons une corrélation entre la réflexion théorique, le matériel extrait du terrain et les concepts d’histoire et de conscience scolaire. De cette manière, nous voulons montrer comment la définition de la mémoire sociale élargit le débat du champ éducatif, notamment, ceux qui font référence à l’enseignement de l’histoire et la construction de la démocratie.
Políticas estatales sobre la profesión docente en el Chile post-autoritario
Authors: Bastías Bastías Lady , Tello Navarro Felipe
Published: August 2019

Cet article présente un essai théorique sur les politiques d’État qui visent la construction de la profession d’enseignant dans un Chili post-autoritaire. Pour cela, la littérature ainsi que des données secondaires serviront d’appui pour réaliser cette première approche de la problématique. D’après cette étude, ces politiques découlent d’un climat de méfiance des enseignants envers l’État. Ce constat devient évident dans les décennies qui suivent le renouveau de la démocratie du pays. Finalement, malgré les efforts du gouvernement pour rendre digne le rôle d’enseignant au Chili, le corps enseignant maintient une attitude méfiante envers les politiques d’État.
L’usage d’un logiciel mathématique et son incidence sur le processus d’enseignement-apprentissage de l'algèbre élémentaire
Authors: Pizarro Rendic Luis Esteban
Published: August 2019

Cet article portant sur l’usage d’un logiciel mathématique et son incident sur le processus d’enseignement et d’apprentissage de l’algèbre élémentaire a pour but de connaître la relation entre le logiciel éducatif mathématique et l’augmentation significative de l’apprentissage, pour des élèves de première année en cursus d’ingénierie. Par ailleurs, ce travail permettra d’établir les avantages et les désavantages de son application dans l’apprentissage des étudiants dans leurs formations personnelles et intellectuelles ainsi que sa cohabitation avec l’actuelle technologie. D’un autre côté, l’intérêt constituera un facteur prépondérant afin de fournir à l’institution des laboratoires informatiques avec des logiciels éducatifs respectifs, en plus de promouvoir des actions et des moyens au service de la quotidienneté des tâches éducatives de l’enseignant.
Pedagogía Holista: ¿el verdadero salvavidas de la educación pública?
Authors: Fuentes Sara , Reyes Paulina
Published: August 2019

L’éducation a évolué tout au long de l’histoire, comme conséquence de ce processus nous pouvons observer que les exigences requises dans les temps modernes ne s’adaptent pas au modèle éducatif traditionnel. C’est pour cette raison que l’implémentation d’une nouvelle méthodologie relative à la pédagogie holistique pourrait résoudre les problèmes éducationnels puisque cela perçoit les étudiants comme individus intégraux, c’est-à-dire que les élèves ne sont pas seulement des nombres qui ont besoin d’être mesurés et constamment évalués. La préoccupation de l’étudiant doit être vue depuis sa perspective intégrale et pour cela les enseignants doivent appréhender et intégrer de nouveaux concepts qu’ils leur permettront d’avancer comme société et à leurs tours de sauver l’éducation publique à l’échelle nationale.
La connaissance : base de la déformation humaine ségrégationniste de l'école
Authors: Cancino Garrido Mario Andrés
Published: August 2019

La connaissance est ce qui permet à l’homme de rendre possible la reconnaissance de la réalité. Ce concept nous est transmis depuis l’école comme un fait que tout le monde devrait savoir. Cependant, il n’est pas expliqué que l’humanité a créé la connaissance. Cette même connaissance dispose de caractéristiques propres à l’intérieur des relations interpersonnelles. Il est possible alors que la construction de la connaissance soit aujourd’hui ce qui empêche de reconnaître tous les êtres humains et laisser de côté la discrimination, en reconnaissant qu’en réalité l’humanité se compose sur la base de l’identité unique et individuelle de chacun des êtres humains reconnaissables comme personnes.
Study of Carbonated Calcium Phosphate Precipitation on Collagen
Authors: Tasomara Riesma , Julia Siti , Sari Yessie Widya , Nurlely Nurlely , Soejoko Djarwani Soeharso
Published: August 2019

Calcium phosphate biocomposites are candidate materials for bone tissue engineering due to their conductivity and biocompatibility. Calcium phosphate could be grown on collagen by precipitation method in long reaction time. Microwave irradiation is rapid method to assist precipitation by reducing reaction time. In order to study carbonated calcium phosphate precipitation on collagen and investigate the influence of microwave irradiation time, the carbonated calcium phosphate has been grown on collagen by microwave assisted precipitation method. The collagen sheets were soaked in carbonated calcium phosphate suspension prepared by using Ca(NO3)2.4H2O, (NH4)2HPO4, and NaHCO3 as starting materials, then microwave irradiated at 270 Watt for 2 minutes, 8 minutes, and 16 minutes. X-ray powder diffraction (XRD) pattern shows the transformation of dicalcium phosphate dyhydrate to apatite crystal structure. Increase in irradiation time had increased crystallinity of carbonate apatite phase. FTIR spectrum had confirmed presence of collagen, phosphate, and carbonate functional group. Scanning electron micrograph showed the presence of collagen with pore, and the carbonated calcium phosphate could attach and be deposited onto collagen.
Physicochemical and Cytotoxicity Characterization of Injectable Bone Substitute Based on Hydroxyapatite - Chitosan - Streptomycin for Spinal Tuberculosis Cases
Authors: Rachmawati Systi Adi , Hikmawati Dyah , Budiatin Aniek Setiya , Putra Alfian Pramudita
Published: August 2019

Injectable bone substitute (IBS) based on hydroxyapatite, chitosan and streptomycin has been developed succesfully. The IBS was made by mixturing 20% w/v hydroxyapatite and varying the chitosan ratio of 60:40, 65:35, 70:30, 75:25 and adding streptomycin as antibiotic substance. The mixture was added with hydroxyl propyl methylcellulose. The synthesis process was steady and no chemical reaction occurred as proven by Fourier Transform Infrared Spectroscopy (FTIR). The in vitro characterization were acidity (pH) and cytotoxicity test (MTT assay), while the physical characterization performed included injectability test, setting time, and morphology. The acidity test showed that the pH samples reached the human normal pH (6.8-7.4) in seven days. The cytotoxicity test proved that the samples were non-toxic. The repasta test showed that the acidity reached the human pH and could release the IBS pasta around 111-150 seconds. The injectability test indicated that IBS had ability to be injected for 95-96%. The setting time in all samples needed 72-166 minutes when it was injected into human bone scaffold model that was able to coat the pore of its scaffold model which proven by Scanning Electron Microscope (SEM) imaging. The pore size of human bone scaffold model was decreased from ±800 μm into ±120 μm. So, IBS pasta based on hydroxyapatite-chitosan-streptomycin in physicochemical and cytotoxicity behaviour is preferable to be applied for spinal tuberculosis cases.
Precipitated Silica from Sodium Silicate by CO2 on Fixed Bed Column
Authors: Dewati Retno , Suprihatin Suprihatin , Sumada Ketut , Muljani Srie
Published: August 2019

The precipitated silica prepared by reaction of sodium silicate and gas CO2 on fixed bed column have been production successfully. In this study, silica from bagasse was extraction by sodium hydroxide 2N solution to produce sodium silicate solution. The sodium silicate solution was dilute by demineralize water to produce some concentration in the range of 0.33-0.98 %SiO2. Fixed bed column has a diameter of 7.5 cm with a height of 50 cm and a pH control apparatus. CO2 gas and sodium silicate liquid are both flowed from under of the column with a specified flow rate. The precipitate process was carried out on a fixed bed column with high of bed in the range of 10-30 cm. The effect of silica concentration and the high of the bed on the characterize of the precipitated silica product have been studied. The precipitated silica product characterized by XRF, XRD, SEM-EDX and BET. The quality of precipitated silica produced in the range concentration of 95-98 w% SiO2, surface area (BET) in the range of 46.1 – 58.8 m2/g.
Hydroxyapatite-Collagen Composite Made from Coral and Chicken Claws for Bone Implant Application
Authors: Siswanto Siswanto , Hikmawati Dyah , Aminatun Aminatun , Zamawi Ichsan Miranda
Published: August 2019

Synthesis of porous hydroxyapatite-collagen composites for bone implant applications has been carried out. Hydroxyapatite synthesized from coral by the precipitation method, while Collagen synthesized from chicken claws. Collagen formation was carried out by freeze-dry technique with variations in freezing time of 2, 4 and 6 hours at -80 ° C. The next process was by drying in a lyophilizer. Characterization of samples was carried out using Fourier Transform Infra Red (FTIR), Scanning Electron Microscopy (SEM), compressive strength test and cytotoxicity test with Microtetrazolium (MTT) assay. FTIR results proved that collagen uptake and hydroxyapatite combine chemically. This is indicated by the absorption of functional groups that did not coincide between collagen and hydroxyapatite functional groups with composites. SEM observations showed that the largest pore size was obtained at freezing for 2 hours which was 774 μm and the smallest in freezing for 6 hours was 640 μm. This pore size was an important parameter of the bone implant because it played a role in the osteoinductive process. The composite compressive strength test results for freezing 2 hours, 4 hours and 6 hours respectively was 737 KPa, 842 KPa and 707.7 KPa. The results of the cytotoxicity test with MTT showed the percentage of cell viability above 100%. This means that the Hydroxyapatite-collagen composite is non-toxic. So, the sample formed has qualified as a bone implant candidate.
Study on Formalization of Oil Palm Trunk Modified by Melamine Formaldehyde
Authors: Manik Tetti Novalina , Mashuri Mashuri , Darminto Darminto
Published: August 2019

The structure, composition and water content of a oil palm wood influence its dynamic mechanical properties. These are very important to study in relation to wood applications. The quality of oil palm wood can be improved through formalization treatment in acid and alkaline conditions and then impregnated by melamine formaldehyde. Variation of formalization time and curing temperature after impregnation on specimens were investigated. Based on physical properties and FTIR characterizations, the formalization time of both acidic and alkaline conditions with the melamine formaldehyde impregnation treatment, showed improving in physical properties of the samples after treatment and this is also indicated with a shift in wave numbers and emergenced a new functional group on FTIR spectra of the samples. The curing temperature has also led to increase density and decrease water content of the specimen, so therefore revealing a decrease of the hygroscopicity of wood.
Synthesis of Carbon Nanosphere at Low Temperatures Based on Bamboo Fiber
Authors: Lahsmin Yulia Kirana , Tahir Dahlang , Abdullah Bualkar , Ilyas Sultan , Mutmainna Inayatul
Published: August 2019

Carbon Nanosphere (CNs) has been successfully synthesized from bamboo fibers at low temperatures by carbonization and activation. For activation used Potassium Hydroxide (KOH) at temperature 105°C, 155°C, 205°C, 255°C and 305°C. X-Ray Diffraction (XRD) spectra shows hexagonal and amorphous phase and Fourier Transform Infrared (FTIR) spectra shows decrease C-O bond with increasing activation temperature. Transmission Electron Microscopy (TEM) image for activation temperature of 105°C confirmed that sources the formation of Carbon Nanosphere. In this study shows bamboo fiber has a high potential as a carbon nanosphere material.
Irradiation Effect on the Structural Properties of Ipomoea batatas L as a Function of Temperature and Time
Authors: Fatimah Siti , Nur Muhammad , Ilyas Sri Dewi Astuty , Tahir Dahlang
Published: August 2019

Purple sweet potato (Ipomoea batatas L) contains high anthocyanin and peonidin glycosides which are useful as powerful natural antioxidants. Microwaves is an electric oven that use for heats and cooks food by exposing electromagnetic radiation produce thermal energy which was influenced to the composition and structural properties of food. In this study, the effect of microwave irradiation on the structural and bonding characteristic of Ipomoea batatas L have been analysis by X-ray diffraction (XRD and Fourier transform infra-red (FTIR), respectively. The composition and the crystallite size was decreases with increasing the temperature and the time of irradiation. The intensity of functional group FTIR spectra shows for 20 minutes irradiation indicated the time for breaking bond of hydroxyl group due to evaporation and re-arrangement of atomic bonding for >20 minutes irradiation. The result in this study as a guided for general public the time maximum irradiation by microwave in the processing Ipomoea batatas L without change the properties
Sorption Efficiency in Dye Removal and Thermal Stability of Sorghum Stem Aerogel
Authors: Septiani Eka Lutfi , Prastuti Okky Putri , Kurniati Yuni , Fauziyah Mar'atul , Widiyastuti Widiyastuti , Setyawan Heru , Wahyudiono Wahyudiono , Kanda Hideki , Goto Motonobu
Published: August 2019

Agroindustry waste containing cellulose compound, Sorghum stem, was utilized to become cellulose aerogel which was then used as dye absorbent in textile dye wastewater. Cellulose was prepared by sorghum stem powder delignification using 6%w of NaOH solution. The ratio of powder and NaOH was varied in 1:12, 1:15, and 1:20. After this process, the powder was synthesized with NaOH/Urea to produce an aerogel by the freeze-drying method. The result shows that a higher amount of NaOH in the delignification process could increase aerogel density and decrease the porosity. Thermal stability and sorption efficiency of the aerogel was analyzed in this study. Higher porosity of aerogel tends to raise % removal in methylene blue absorption. This study reveals that aerogel three times more effective than activated carbon in dye removal.
Investigation of Structural and Antifungal Behaviors of Nano-Sized Anatase Titanium Dioxide Synthesized by Co-Precipitation Route
Authors: Taufiq Ahmad , Arista Deny , Sunaryono Sunaryono , Saputro Rosy Eko , Hidayat Nurul , Soontaranon Siriwat , Handoko Erfan , Darminto Darminto
Published: August 2019

Nowadays, the application of nano-sized anatase titanium dioxide particles becomes one of the essential research focuses by many experts, especially for biomedical applications. In this work, we report the utilization of coprecipitation route in preparing nano-sized anatase titanium dioxide as an antifungal agent. The data analysis for the XRD data of the titanium dioxide particles showed that the sample crystallized with anatase structure and sized in the nanometric size of 13.30 nm. The particle size obtained from Scherrer’s analysis of the XRD data was quite similar to the particle size obtained from electron microscopy investigation. Furthermore, the small-angle scattering data presented that the anatase titanium dioxide constructed a 3-dimensional structure with a compact structure originating from the fractal dimension value of approximately 3. The functional groups of the nano-sized anatase titanium dioxide were traced in the wavelength range of 500-1500 cm-1 showing the presence of Ti-O bonding. Interestingly, the prepared sample in this experiment exhibited an excellent performance as an antifungal agent represented by inhibition zone diameter of 3.59 mm.
Optimization of Polydimethylsiloxane Synthesized Parameters as Vitreous Humour Substitutes
Authors: Setiadji Soni , Fitrilawati Fitrilawati , Fauza Anna Niska , Ardi Atikah , Novianti Ressa , Syakir Norman , Waslaluddin Waslaluddin , Rahayu Iman , Kartasasmita Arief Sjamsulaksan , Risdiana Risdiana
Published: August 2019

Polydimethylsiloxane (PDMS) with two type viscosity that commonly used as vitreous humour substitutes in vitreoretinal surgery has been successfully synthesized by ring-opening polymerization. Optimization of synthesized parameters such as ratio of monomer and chain terminator, the amount of initiator, mixing temperature and reaction time was carried out to obtain PDMS materials having similar properties with commercial product. PDMS with viscosity of 1.17 Pas that very close to viscosity of commercial PDMS of 1.08 Pas, was successfully synthesized with a ratio of 26:10 monomer and terminator chain, 0.58 M of initiator KOH, 170 oC of mixing temperature and 35 minutes of reaction time. By changing reaction time to 40 minutes, PDMS was successfully synthesized with viscosity of 3.42 that similar to that of commercial one.
The Effects of Split Valence Basis Sets on Muon Hyperfine Interaction in Guanine Nucleobase and Nucleotide Structures
Authors: Zaharim Wan Nurfadhilah , Shukri Sulaiman , Abu Bakar Siti Nuramira , Ismail Nur Eliana , Rozak Harison , Watanabe Isao
Published: August 2019

The DFT cluster method was employed to investigate the electronic structures and muonium hyperfine interactions in guanine nucleobase and nucleotide using three different basis sets. The total energy and Fermi contact values were calculated for muon trapped at carbon '8'. The three basis sets, 6-31G, 6-311G and 6-311G(d,p), were used in tandem with the B3LYP functional. There are significant quantitative differences in the calculated total energy. 6-311G(d,p) produced the lowest total energy as compared to the other basis sets. The lowering of the total energy is due to the increase in the number of basis functions to describe the atomic orbitals, which is consistent with the postulate on basis set completeness. The 6-31G basis set produced the muon Fermi contact value that is the closest to the experimental value. The calculated Fermi contact values for the nucleobase and nucleotide are significantly lowered in going from the double-zeta to the triple-zeta basis set by 5% and 4% respectively. The lowering of the Fermi contact value can be attributed to the extension of the triple-zeta basis set in describing the valence atomic orbitals. The presence of the sugar phosphate group in the nucleotide instead of the methyl group tends to lower the Fermi contact value. Thus, the sugar phosphate group should be taken into consideration when designing a calculation model.
Electrical Transport Properties of Perovskite La0.7Sr0.2Ba0.1Mn1-xNixO3(x = 0 and 0.1) Manganite
Authors: Munazat Dicky Rezky , Kurniawan Budhy , Imaduddin Agung
Published: August 2019

The effect of nickel substitution on the electrical transport properties of La0.7Sr0.2Ba0.1Mn1-xNixO3 (x = 0 and 0.1) manganite have been studied. The temperature dependence of resistivity of the samples shows that nickel substitution increases the overall resistivity. Exchange probability calculation shows that the ferromagnetic (FM) coupling inside the sample decreases upon nickel substitution, which induces antiferromagnetic (AFM) coupling inside the sample. These results are suitable with the reduction in the electronic bandwidth value. Comparison of experimental data with theoretical models shows that the electrical behavior of the samples is well explained by a theory based on percolation models. Present result suggests that the electrical behavior of the sample was influenced by scattering and interaction between electron, phonon, and magnon. Nickel substitution also decrease the metal-insulator transition temperature and theoretical Curie temperature from around 328 K to 249 K and around 349 K to 275 K respectively.
Magnetic Properties of YBa2Cu3O6 Studied by Density Functional Theory Calculations
Authors: Ramli Irwan , Mohd Tajudin Saidah Sakinah , Ramadhan Muhammad Redo , Sari Dita Puspita , Shukri Sulaiman , Mohamed-Ibrahim Mohamed Ismail , Kurniawan Budhy , Watanabe Isao
Published: August 2019

We present the results of investigations on the muon sitesin YBa2Cu3O6(YBCO6) by using the density functional theory (DFT) calculation technique in order to achieve a deeper understanding of its magnetic properties. We included the Hubbard parameter, U, among electrons in our DFT calculations in order to simulate realistic electronic and magnetic state in YBCO6. We found that the U value does not affect the muon sites in YBCO6but the related internal field has strong dependence on U value. In this study, we tried to optimize the value of Ucomparing with the experimental result.
Physical Properties of Encapsulated Iron Oxide
Authors: Saragi Togar , Permana Bayu , Therigan Arnold , Hidayat Sahrul , Syakir Norman , Risdiana Risdiana
Published: August 2019

The size effect of magnetic nanoparticles provides a various magnetic characteristic as a change of domain size. We report, synthesis of core-shell iron oxide and magnetic properties. Iron oxide particles were synthesized by co-precipitation method of iron (III) FeCl3.6H2O, iron (II) FeCl2.4H2O, in the mixture of with or without TEOS to investigated the physical properties. From XRD measurement, it was observed that all iron oxide particles with or without mixture of SiO2 has a hematite phase of a-Fe2O3. From M-H loop measurement, it was observed that the iron oxide without SiO2 has a ferromagnetic characteristic, while the iron oxide with SiO2 showed a medium state as a contribution of superparamagnetic and ferromagnetic properties.
Magnetic Study of the Lower Critical Field of Organic Superconductor λ-(BETS)2GaCl4
Authors: Sari Dita Puspita , Hiraki Koichi , Nakano Takehito , Hagiwara Masayuki , Nozue Yasuo , Kusakawa Takumi , Hori Akiko , Yamamoto Ayako , Watanabe Isao , Ishii Yasuyuki
Published: August 2019

The lower critical field of type-II organic layered superconductor λ-(BETS)2GaCl4 has been estimated by magnetic measurement. In this study, the demagnetization factor of a needle-like sample shape has been taken into account for the measurements by applying external field, parallel and perpendicular to the conducting plane. The lower critical field for the field perpendicular to the conducting plane is 8(1) G, convincing the previous study. This estimation allows us to predict the ideal external field that should be applied for London penetration depth measurement by using muon-spin rotation (SR) spectroscopy.
The Study on Tuning Photoluminescence of Colloidal Graphene Quantum Dots Synthesized through Laser Ablation
Authors: Murdaka Fiqhri Heda , Nugroho Agustinus Agung , Kusumaatmaja Ahmad , Isnaeni Isnaeni , Santoso Iman
Published: August 2019

We report photoluminescence study of Colloidal Graphene Quantum Dots (GQDs) that synthesized from ablation of rGO solution. The rGO solution was ablated using 800 nm Ti-Sapphire femtosecond laser by varying the synthesize parameters such as laser power and ablation time. We observed that changing laser power 1 Watt to become 1.7 Watt and time ablation 20 minutes to become 60 minuteswill alterate the Photoluminescence (PL) curve peak of GQDs. In case of ablation power variation, PL data shows that the PL curve peak excited by 280 nm laser changed from 369.09 nm to 371.02 nm, and when it excited by 290 nm the PL curve peak slightly changed from 388.17 nm to 393.8 nm. The alteration of Photoluminescence peak is also observed in the variation of time ablation experiment, The PL curve peaks from GQDs time ablation variation samples excited by 280 nm were slightly changed from 376.81 nm to 373.59 nm, and when it excited by 290 nm laser, the PL curve peak is 391.55 nm then changed to 392.11. The change of PL peak on laser power or time ablation variation shows that both parameters will alter either the size, shape, or the edge-type of GQDs.
Characterization of TiN Oxide Doping Antimony Thin Layer with Sol- Gel Spin Coating Method for Electronic Device
Authors: Doyan Aris , Susilawati Susilawati , Harjono Ahmad , Azzahra Syifa , Taufik Muhammad
Published: August 2019

Antimony tin oxide coating research has been carried out using a spin sol gel coating method with different doping concentrations (0, 5, 10, 15, 20)%. The results of the study on the morphological structure (SEM) of thin films that have been carried out showed more cracks on the surface of the morphology of thin layers without doping compared to thin layers with doping antimony. The Results of crystal structure of XRD in thin antimony doping tin oxide layer shows the grinding index of tin oxide crystals, 101, 110, 211, 220. In grain size, with increasing antimony doping percentage, the average grain size decreases. The optical properties using UV-Vis in thin films of antimony tin oxide doping show samples including semiconductor materials that can be used as electronic devices as seen from the reduction of this energy gap (3,680 - 3,574) eV. Also seen is an increase in the percentage of antimony doping and repetition of layers, the lower the transmissions value, but the value of absorbance of the thin layer increases.
Complex Permittivity, Permeability and Microwave Absorption Studies of Double Layer Magnetic Absorbers Based on BaFe12O19 and BaFe10CoZnO19
Authors: Handoko Erfan , Sugihartono Iwan , Marpaung Mangasi Alion , Cahyana Ucu , Aritonang Sovian , Jalil Zulkarnain , Rusmono Rusmono , Taufiq Ahmad , Sunaryono Sunaryono , Randa Maulana , Alaydrus Mudrik
Published: August 2019

Microwave absorption properties of double layer magnetic absorbers based on BaFe12O19 (BFO) and BaFe10CoZnO19 (BFCZO) have been investigated in X-band (8.2–12.4 GHz) frequencies. The BFO and BFCZO were prepared by using a solid state reaction process. The crystalline structures were investigated by X-ray diffraction (XRD), The complex permittivity and permeability are determined using Vector Network Analyzer (VNA) in a range from 8.2 GHz to 12.4 GHz. The double layer magnetic absorbers, composed of the BFO as matching layer and the BFCZO as absorption layer, with a total thickness of 5 mm, showed an effective reflection loss (RL) an effective absorbing bandwidth below –5 dB.
Analysis of Physical Properties, Crystal Structure and Magnetic Properties of Barium Hexaferrite Doped with 2 % wt. of SrO and Prepared by Coprecipitation Method
Authors: Suprapedi Suprapedi , Muljadi Muljadi , Djuhana Dede , Ramlan Ramlan
Published: August 2019

The purpose of this study is to determine the effect of the addition of 2 % SrO on physical, magnetic properties and crystal structure of BaO6Fe2O3. In this study, the coprecipitation method was used with raw materials BaCl2, FeCl3 and SrCl3 and Ba-ferrite composition is used based on the ratio of mole BaO: Fe2O3 = 1: 6, while SrO is used 2% of the weight of Ba-ferrite. The raw materials are dissolved in distilled water, then added a solution (50%) of ammonia to form a perfect precipitate. The precipitate after filtering was dried in an oven at 100°C until dry, then crushed with mortar and partially taken for analysis with DTA / TG. The fine powder was calcined at 800 ° C and held for one hour using an electric furnace. The calcined samples were crushed with mortar and fine powder was added 1% wt.of PVA adhesive and formed with a pressure of 40 MPa to obtaine a pellet sample. The pellet samples were then sintered at 1150°C and hold for 1 hour. Furthermore, the sintered samples were characterized such as measurement of bulk density, magnetic properties with gauss meters and VSM and measurements with XRD. The results of characterization show that the addition of additives 2% of SrO can provide an increase in physical properties and magnetic properties (remanence). But for the crystal structure of XRD analysis there is no change, a single phase is formed, namely BaFe12O19.
Effect of Copper Substitution on the Electrical Transport Properties of La0.7Ba0.1Sr0.2Mn1-xCuxO 3 (X = 0 and 0.05) Manganites
Authors: Kurniawan Budhy , Razaq Dhawud Sabilur , Imaduddin Agung
Published: August 2019

A systematic investigation of polycrystalline La0.7Ba0.1Sr0.2Mn1-xCuxO3 (x = 0 and 0.5) manganite has been conducted with a view to understand the effect of copper substitution on the electrical transport properties and its correlation with structural and morphological properties. The structural and morphological properties of the sample without copper content (x = 0) have been reported previously, while in this research, the structural and morphological properties of sample with 5% copper content (x = 0.5) will be reported. Structural comparison with previous research shows that 5% copper content does not change the rhombohedral structure of the sample without copper content. Comparison of resistivity (ρ) data with the theoretical model shows that the electrical properties of both samples are well described using the electron-electron, electron-phonon, electron-magnon, and kondo-like spin dependent scattering theory. Furthermore, percolation theory which have been used in the model shows that ferromagnetic phase and paramagnetic phase coexisted in both samples. Through copper substitution, the overall resistivity of the sample decrease compared to the sample without copper content. Furthermore, percolation theory demonstrates that ferromagnetic phase of the sample is decreasing as copper ions substituted manganese ion.
Enhanced Microwave Absorbing Capabilities of Multilayer Absorbers Based on BaFe12O19 and Fe3O4
Authors: Handoko Erfan , Sugihartono Iwan , Marpaung Mangasi Alion , Cahyana Ucu , Aritonang Sovian , Jalil Zulkarnain , Rusmono Rusmono , Taufiq Ahmad , Sunaryono Sunaryono , Alaydrus Mudrik
Published: August 2019

In order to enhance a new microwave absorbing capabilities in the X-band frequency range, polycrystalline magnetic materials of BaFe12O19 barium hexaferrite were fabricated through conventional ceramic method and the Fe3O4 powder from iron sand were prepared through magnetic separation after milling process by using planetary ball mill. Microwave absorbing capabilities of multilayer absorbers, composed of BaFe12O19 barium hexaferrite and the Fe3O4 powder, with a total thickness of 10 mm, were investigated by a vector network analyzer (VNA) in the range of 8.2 –12.4 GHz. According to transmission line theory, reflection of microwave radiations from multilayer magnetic materials is calculated. The reflection loss (RL) strongly depends on thickness of multilayer absorbers and showed an optimal RL. Keywords : BaFe12O19, Fe3O4 powder, reflection loss, multilayer absorbers.