bluuebunny/crossref_metadata_2025 huggingface dataset:
Thunderstorm activity in typhoon Lionrock (2016)
Authors: Shabaganova S N , Tarabukina L D , Kozlov V I
Published: September 2019

On Aug. 29, 2016, the tropical cyclone Lionrock was reported to turn into an extra-tropical storm and go to the shore of the Primorsky Region as monitoring shows, which brought about significant precipitation growth recorded in the north of the coast. Many surveys show the tropical cyclones in this area to transform into extra-tropical ones and become powerful mid-latitude storms with significant damage to coastal and maritime areas. The paper uses WWLLN (World Wide Lightning Location Network) data to study the thunderstorm activity while the tropical cyclone reaches the typhoon level with the maximum wind velocity. This made it possible to identify parameters’ variations of thunderstorm activity during atmospheric vortex phenomena. It also enabled us to determine the emergency probability due to a thunderstorm.
Space-time variability of wave characteristics near the coasts of the Southern Kuril Islands
Authors: Borisov A S , Kirillov K V
Published: September 2019

Significant wave heights and most probable wave heights in the nearshore areas of the Southern Kuril Islands are considered in this paper. These characteristics were obtained from data of in-situ measurements of hydrostatic pressure in the depth range from 5 to 25 m. The measurements have been performed in 2008 and 2009. It is shown in the paper that relatively calm sea surface was observed in time period from July till first half of September. Most probable wave heights varied from 0.17 m to 0.27 m and maximal values of significant wave heights varied from 0.75 m to 1m in the depth range from 15 to 25 m. For depths less than 15 m most probable wave heights varied from 0.05 m to 0.1 m and maximal values of significant wave heights varied from 0.68 m to 1m. Time period from second half of September is characterized as stormy period. Maximal values of significant wave height reached 5 m at that time and most probable wave heights varied from 0.1 to 1 m depending on depth and location. Period from January till April can be characterized by high number of moderate storms with maximal value of significant wave heights 1.8 m and most probable wave heights from 0.13 to 0.33 m.
New data on the morphology and development of volcanic lakes of the Kuril-Kamchatka region
Authors: Kozlov D N , Lebedeva E V
Published: September 2019

Volcanic lakes are of particular interest to geomorphologists and other professionals due to the diversity of the basins forms and the very dynamic development of lake systems. The origin and evolution of these water bodies are closely related to active volcanic and post-volcanic processes, they are characterized by rapid changes of shape, level, composition of water and characteristics of the coast. Usually bounded by craters, calderas and in the immediate vicinity of volcanoes, these lakes present a kind of by-product of volcanism. In the Kuril-Kamchatka region, two types of lakes can be distinguished: 1) dynamically developing young, some of them ephemeral, located on active volcanoes, in active craters. In these lakes, as a rule, there are active gas-hydrothermal manifestations, and their waters are highly mineralized; 2) stable (relict) lakes in the calderas of dormant and extinct volcanoes. Lakes of this type usually do not have explosive funnels or active gas hydrotherms, and the water in them is slightly mineralized. It suggests a much more ancient age and the decreasing of post-volcanic activity in caldera depressions. Lakes of different types can exist close to each other and form a single communicating systems.
Coastal retreat at Kharasaveyskoye gas and condensate field area, Kara Sea, Russia since 1970s
Authors: Belova N G , Ogorodov S A , Shabanova N N , Maslakov A A
Published: September 2019

Changes in coastal retreat rates, both spatial and temporal, are considered at the area of Kharasaveyskoye gas and condensate field for the period before the exploration till now. In the study area, the presence of permafrost makes the erosional coasts vulnerable to rising temperatures. The increase in air temperatures contributes to the thawing of coastal sediments and their accelerated destruction. And a decrease in sea ice area potentially increases the wave fetch. The rapidly changing climate of the Arctic should influence the processes of destruction of frozen coasts. At West Yamal Peninsula near Cape Kharasavey the average coastal retreat rate is 1.1 m per year (1977-2016) for 7 km of coastline. Based on the analysis of multi-temporal aerial and space images, it has been established that the maximum retreat rates are typical of coastal segments composed of icy sediments. As for temporal variability, the maximum rate of destruction was observed in 1977-1988 (up to 6.5 m per year) immediately after the beginning of economic development of the territory. In this key site, human impact affects the rate of coastal destruction more than variations in hydrometeorological parameters.
Vetrovoy isthmus of iturup island – holocene strait
Authors: Afanas’ev V V , Ignatov E I , Uba A V , Dunaev N N , Leontiev I O , Gorbunov A O
Published: September 2019

Explosive volcanism is equally important as the features of neotectonic and modern movements for the development of the Kurile Islands coast, as it led to the afflux of hundreds of millions of cubic meters of pumisopyroclastic material and tephra into the wave processing zone of coastal zones of the Pleistocene-Holocene. Morphometric, georadar and paleogeographic studies of the coastal-sea relief of Iturup Island allowed to determine several levels of marine terraces in the pyroclastic sediments of the Late Pleistocene-Holocene, and also the presence of a buried sea strait that existed at least in the middle Holocene. Taking into account the values of deformation of the terrace levels, the depth of the strait was 10-15 meters. Volcanic-tectonic deformations connected with eruptions near the central part of the Vetrovoy Isthmus led to the collapse of pumice packs at the section basement of the sea coastal ledge with a layer of beach material on the roof (LU-9223-6320 ± 100, cal. Year BP). Thus, in the mid-late Holocene, after the sea level was risen to the nowadays levels, at least two more pyroclastic series were deposited, the last of which one is dated 1050 ± 70 cal. BP – LU-8685.
Identification of oil and gas bearing objects using geophysical data in the eastern part of the Gulf of Suez, Egypt
Authors: Tarshan Ahmed , Shimanskiy S V
Published: September 2019

The airborne magnetic data is considered as one of the best methods to delineate the depth to basement layer. The airborne magnetic survey data obtained from the Egyptian Nuclear Materials Authority. Data is accurately processed, interpreted. Two-dimensional (2D) modeling was performed by GM-SYS, along one selected profile yielded from RTP map. In addition to that, three-dimensional (3D) Euler Deconvolution method was performed to delineate the depth to basement layer. Euler solutions were applied on RTP Grid by structural indexes 0, 1, 2, and 3 to select the best solution. The sedimentary succession of the study area is created using seismic data and well data. Petroleum system model was established to predict the locations of hydrocarbons within the study area. The results of PetroMod confirmed that the area is very promising for hydrocarbon aggregations, and also new hydrocarbon aggregations have been discovered.
Vegetation of the Yuzhno-Sakhalinsky mud volcano as an indicator of activity
Authors: Kopanina A V
Published: September 2019

In the present paper we have addressed the issue of identification of mud volcanic activity based upon the vegetation, its structure and dynamics, as well as the structural peculiarities of woody plants. The study was conducted using an integrated approach which includes: the description of vegetation and the structural analysis of woody plants that grow at various distances from the eruptive centre of the volcano. The obtained data on the vegetation suggest that the Yuzhno-Sakhalinsky mud volcano is a far more extensive landscape feature that it was considered before, with an eruptive centre which changes its location every 150-300 years.
Hydrogen Induced Cracking of API X52 and X60 Sour Service Steels Subjected to Pre-Strain under Prolonged H2S Exposure
Authors: Korda A.A. , Taufiq T.
Published: September 2019

The effect of plastic deformation on API X52 and X60 sour service steels on hydrogen induced cracking was studied. Plastic deformation was performed with a tensile pre-strain with the percentage variation of strain. The HIC test was carried out with a duration of 168 hours of hydrogen charging to investigate the cracking behavior. After hydrogen charging, the cross sections of both steels were observed to find out hydrogen cracks. Ultrasonic testing was carried out on the specimen surface to see the distribution of laminated cracks. The hydrogen crack surface was observed using SEM. The results showed that the values of CSR, CLR and CTR increased with increasing percentage of pre-strain. Ultrasonic testing showed that the area influenced by HIC increased with increasing percentage of pre-strain. The susceptibility of API X52SS and X60SS to HIC increases with increasing percent of pre-strain. API Steel X52SS has better HIC resistance than X60SS on high pre-strain.
Effect of Shielding Gas and Filler Metal to Microstructure of Dissimilar Welded Joint Between Austenitic Stainless Steel and Low Carbon Steel
Authors: Purnama Dewin , Oktadinata Herry
Published: September 2019

Welding of dissimilar metals involves different types of metals which have different chemical composition, mechanical and thermal properties. This paper presents a study on dissimilar metal weld between type 304 stainless steel and SS400 carbon steel. The steel plates were welded by using different filler metals (solid wire, flux-cored wire) and different shielding gases (100%CO2, 90%Ar+10%CO2). Then the weldments were observed by optical microscope, scanning electron microscope and EDX analysis. It seems that the weldments which were welded by using 100%CO2 shielding gas have significant amount of inclusions in weld metal compared to 90%Ar+10%CO2 shielding gas mixture. The EDX analysis shown the inclusions are oxides which consist of some elements (C, Si, Cr, Mn) with O. The weldment which was welded by using 90%Ar+10%CO2 shielding gas mixture and solid wire has much less inclusions in weld metal.
Effect of Applied Voltage and Coating Time on Nano Hydroxyapatite Coating on Titanium Alloy Ti6Al4V Using Electrophoretic Deposition for Orthopaedic Implant Application
Authors: Nuswantoro Nuzul Ficky , Budiman Ikhwal , Septiawarman Andre , Tjong Djong Hon , Manjas Menkher , Gunawarman
Published: September 2019

Nanoparticles of Hydroxyapatite (HA) were coated onto biocompatible titanium alloy, Ti6Al4V ELI using Electrophoretic Deposition (EPD) in order to improve its bioactivity. Electrophoretic Deposition (EPD) has been selected as the coating method because of the simplicity of the instrument, inexpensive cost, and ability to coat complicated products. This study, therefore, aims to investigate the effect of voltage and coating time of EPD process on increasing of implant mass as a parameter of deposition rate, coating thickness, and surface coverage of the HA on implant screw prototype products. Voltages were controlled in the range of 3, 5, and 7 volt and coating times were in the range of 3, 5, and 7 minutes. Surface morphology was examined using scanning electron microscopy (SEM). Coating thickness was measured by coating thickness gauges. While surface coverage was determined using ImageJ software. Based on the result, applied voltage and coating time affects the mass growth of samples and HA coating thickness in positive correlation. However, on the surface coverage, applied voltage and coating time reach the optimum value at 5 volt and 5 minutes. The best HA coating in which fulfilling the standard for orthopaedic implants was obtained at 5 volts for 5 minutes with mass growth is 0.00107 g, coating thickness are 79.13 µm, and surface coverage is 97.89%. HA coating thickness that produced in this research has fulfilled the desired coating thickness for orthopaedic implant application (50-100µm). SEM micrographs show that nano-HA is coated the alloy surface uniformly at these parameters. It can be concluded that these parameters can be applied to coat titanium Ti6Al4V ELI with HA for improving bioactivity in the orthopaedic application.
Effect of Addition Tahongai Leaf Extract (Kleinhovia hospita Linn.) As Organic Inhibitor on 1040 AISI Steel
Authors: Yunita Triana , Putri Kusuma Asih Wentika , Novita Sari Eli , Sulistijono
Published: September 2019

This research will study about corrosion inhibition by using tahongai leaf extract (Kleinhovia hospita Linn.) in a 3.5% NaCl environment. The inhibitor is extracted using maceration process from Tahongai leaf (Kleinhovia hospita Linn.). Testing of antioxidant activity using DPPH method gives result that antioxidant activity of tahongai leaf extract (Kleinhovia hospita Linn.) is strong antioxidant (96%) compared to vitamin C (98%), functional group test by FTIR method indicates that tahongai leaf extract (Kleinhovia hospita Linn.) contain flavonoid shown by O-H bond (3357.41 cm−1), double bond C=C (164 3.36 cm−1), C-H bond (2922.24 cm−1, 1460.69 cm−1, 1375.57 cm−1), Efficiency of inhibition reach 99.9825% for addition of inhibitor with concentration 200 ppm and duration of immersion 20 days. This inhibition behavior is also supported by polarization measurements where the lowest corrosion rate of 8.3x10−4 mm/year is obtained at the same concentration and immersion time.
Corrosion Behaviour of Collagen Coated and Uncoated Biomedical Titanium Alloy (TNTZ) Within Human Synovial Fluid
Authors: Fajri Hidayatul , Ariani Windy , Gunawarman  , Tjong Djong Hon , Manjas Menkher
Published: September 2019

The corrosion behavior of uncoated Ti-29Nb-13Ta-4.6Zr (TNTZ) and collagen-coated TNTZ within human synovial fluid + NaCl 0.9% solution was investigated using immersion test in order to know the effectivity of collagen to increase bioactivity and also reducing corrosion rate as a coating material. Collagen was selected as coating material because of the ability of adhesion cell and increasing bone healing process. The immersion test has been used as corrosion method due to its simplicity and inexpensive. The immersion time in this study was for 2, 4, and 6 weeks. Surface morphology of material was examined by scanning electron microscope (SEM). Corrosion rate was calculated by measuring degradation of coating mass during the corrosion process. While mechanical property (hardness) of material was measured by microhardness testing. The result of this study showed that collagen coating has reduced the corrosion rate of TNTZ in the human synovial fluid where the corrosion rate of the coated TNTZ is 0.00125 mmpy and the corrosion rate of uncoated one is 0.00262 mmpy after 6 weeks immersion. On the other hand, the hardness of coated TNTZ is higher than the uncoated one. It can be concluded that the collagen coating increases both corrosion resistant and mechanical properties of TNTZ.
Effect of Aluminum and Silicon Antioxidants Addition on Porosity, Cold Crushing Strength, Wear Resistance and Hydration Effect of Alumina Spinel Refractories
Authors: Fernando E.D. , Korda A.A.
Published: September 2019

Due to their high resistance and wear resistance, alumina spinel (MgAl2O4) are widely used for slide gate on ladle. The characteristics strongly depend on the formation of ceramic phases in the matrix. Addition of antioxidants is used to prevent the graphite oxidation, possibly leading to porosity increase. Currently, other problem appears as the consequences of climate change. The object of this research is to study the effect of antioxidants addition in temperature variations. The influence of Al and Si addition is investigated by means of XRD, SEM, TGA-DTA, apparent porosity, CCS, wear resistance and hydration resistance tests. It was found that lowest porosity, highest CCS and best wear resistance were reached by sample containing Al 5% in 1400°C, while best hydration resistance was reached by sample containing Si 5%.
The Influence of Mold Material on Cooling Curve, Solidification Parameters, and Micro-hardness of Al–6wt.%Si in Unidirectional Solidification
Authors: Masnur D , Suyitno  , Malau V
Published: September 2019

The influence of mold material on cooling curve, solidification parameters, and micro-hardness were investigated. Al–6wt.% Si in clay and stainless steel mold was directionally solidified using vertical Bridgman type furnace. The samples were heated up to 700°C at 1.9°C/s heat rate, held for 60 minutes, cooled, and withdrawn at 40 µm/s. The results show that the increasing of thermal conductivity by 72% affects cooling curve shape, solidification parameters, and micro-hardness. Furthermore, comparative evaluation of the exponent value of the function of micro-hardness to distance and micro-hardness to growth rate also have been made to proposed the range of exponent value for each mold material.
The Effect of Variation of Nano SiC Reinforcement Particle Addition to Mechanical Properties of Mg/Nano SiC Composite by Stir Casting Method
Authors: Syahrial A Z , Hannan N D
Published: September 2019

Composites are advanced material which is being developed that contains of two materials or more in order to improve the mechanical properties. Magnesium composite is a suitable material beside aluminium and its alloy to be applicated as vehicle body structure due to its lightweight and its low density. Thus, the vehicle body structure with lightweight and good mechanical properties can be achieved. In this research, magnesium composite is fabricated by mixing magnesium as composite matrix and nano SiC as reinforcement particle with the variation of the volume fraction 0.05 %vf, 0.10 %vf, 0.15 %vf, 0.20 %vf, and 0.25 %vf with stir casting as fabrication methods. To characterize the composite product, several testing were done, which were chemical composition characterization, metallographic observation, SEM-EDS characterization, XRD characterization, hardness testing, wear testing, and impact testing. The result of this research shows that with nano SiC addition as reinforcement particle will increase mechanical properties of magnesium composite. The best mechanical properties of magnesium composite is shown by the addition of 0.15 %vf nano SiC. The result shows the brinnel hardness number of this composition is 39 HB and 0.0052 mm3/m wear rate. Mechanical properties of magnesium composite are increased due to several strengthening mechanism such as grain size reduction and Orowan strengthening mechanism.
Relationship Between Heat Treatment And Mechanical Properties Of Al-Si-Mg Alloy
Authors: Namikawa Yuki , Sugio Kenjiro , Sasaki Gen , Tabata Junji , Fuyama Nobuyuki
Published: September 2019

The relationship between heat treatment and mechanical properties of Al-Si-Mg alloy was investigated. Solution treatment at 808K for 6 hours, preliminary aging at room temperature for 60 hours and artificial aging at 473K for 1 hours were conducted. Not preliminary aged samples were prepared for comparison. The strength improved and the elongation decreased with increasing the amount of Mg. This trend was seen both preliminary aged and not preliminary aged samples. However, preliminary aged samples showed relatively high tensile strength and elongation comparing with not preliminary aged samples. EPMA analysis revealed that the precipitation of Mg2Si in preliminary aged samples was larger than that of not preliminary aged samples, and which possibly contributed to the improvement of strength of the preliminary aged samples. Thermodynamic calculation showed that Mg2Si phase was not undissolved at the solution temperature, 808K, and these undissolved Mg2Si particles might influenced on mechanical properties negatively.
Effects Of Ionic Immersion Time On Optical Properties Of Cu2ZnSnS4(CZTS) Deposited by Successive Ionic Layer Adsorption And Reaction (SILAR)
Authors: Rukini Asywendi , Reza Alvian , Munir Badrul
Published: September 2019

Cu2ZnSnS4(CZTS) thin films fabricated by successive ionic layer adsorption and reaction (SILAR) method is a promising combination to actualize a low cost thin films Solar Cell (TFSC). Ionic exchange and rinsing time are critical point for ionic layer formation in SILAR method. The purpose of this study is to investigate the influence of cationic and anionic immersing time on the band gap energy of CZTS. Immersing time was varied into 10, 20, 30 and 40 seconds for both deposited and annealed samples, which annealing was conducted on 300°C for two hours. Deposited results showed a linear increase on band gap energy as cationic immersing time extended. Whereas, nonlinear increment with optimum band gap 1.35eV at 30 seconds immersion happened for anionic time variation samples. Annealed CZTS with cationic time variation also showed a linear increasing band gap. Meanwhile, annealed with anionic time variation showed a backward tendency of the deposited samples which the band gap decrease nonlinearly as anionic immersing time lengthened.
The Effect of Adding Synthesis Silica from Rice Husk as Cement Substitution for High Strength Concrete
Authors: Fajar Fatriansyah J , Dhaneswara D , Aida Khairunnisa S , Kusumawardhani D
Published: September 2019

The synthesis of silica from agricultural waste was conducted. The thermal decomposition was conducted at 700°C which yields white-brown silica powder. Acid mechano-chemical method was done to reduce the size particle of silica and homogenize the distribution particle. The variables used were the rotational speed of planetary ball-mill at 22 rpm and the addition of acid (HCl 1M). Under controlled burning, the highly reactive ash (silica products) that is produced can be used as a supplementary cementing material or in the production of high strength concrete (HSC). The samples were tested during its 28th day to know its compressive strength.
Failure Analysis of Superheater Boiler Tube SA 213 T12
Authors: Ardy Husaini , Bangun Deri Andika
Published: September 2019

Superheater tubes SA213 T12 (OD = 57 mm, WT = 6 mm) has been in service for 11 years in a supercritical coal fired boiler (315 MW). Tubes operating temperature are 430°C and pressure is 11 MPa. Failure occurred on tube no. 20, row 2. Three tubes specimens from the same row (failed tube, tube no. 3, and no. 4), were drawn for laboratory examinations. Vickers microhardnesses of failed and no. 3 tubes are the same (140 VHN), while tube no. 4 hardness is 170 VHN. These hardness values are much lower compared to the new tube (192 VHN). The lower hardness value of failed tube is due to complete decomposition of pearlite colonies in inner and outer side of failed tube to ferrite and spheroidized cementite. Failure of tube is characterized by thin lip rupture which indicated that the tube circumferential deformation occur gradually following spheroidization process. Failure by intergranular crack occurred along grain bondaries when the stress on the tube wall (hoop stress) exceeding material strength at service temperature. Tube no. 3 and 4 are partially spheroidized, mostly on the innerside. The severity of microstructure damage is related to the flow direction of flue gas, from tube no. 1 to no.2, no.3 and so on. Tube no. 1 was survived because it was protected by a front cover that will limit heat transfer from the flue gas. The previous failure analysis of similar boiler tube revealed that the hardness of the bulging tube is about 140 VHN which is the same as the hardness of the failed tube (no. 2) and no.3. Tube no. 3 is in the early stage of damage and shall be replaced because the hardness is much lower than 170 VHN. The effect of flue gas flow direction not only affects the hardness and microstructure but also deposit thickness. Deposit thickness in tube no. 2, 3, and 4 are 149, 123, and 100 µm respectively. Thicker deposit in tube no. 2 is also contributed to premature failure of this tube compared to the others. The local temperature of tube wall will be higher because thick deposit will reduce heat transfer between flue gas and steam inside the tube.
The Tensile Strength of Petung Bamboo Fiber Reinforced Epoxy Composites: The Effects of Alkali Treatment, Composites Manufacturing, and Water Absorption
Authors: Refiadi Gunawan , Syamsiar Yusi , Judawisastra Hermawan
Published: September 2019

Natural fiber application due to its competitiveness attracted many research in green composites. However, the tensile properties of natural fiber composites might be influenced by several factors such as treatment of the fibers, manufacturing processes, and water absorption levels. In this research, we use petung bamboo fibers as natural fibers candidate for a good reinforcement in green composites. The study focused on the tensile property of bamboo fiber reinforced epoxy composites due to alkali treatment, manufacturing process, and water absorption. The composites were made with three variations: the fibers were varied without and with alkaline treatment (5% NaOH); manual lay-up method and hot press were applied as manufacturing variation; moisture content in the composites was varied in dry condition and after water absorption treatment. Tensile testing and Scanning Electron Microscope (SEM), were performed to improve tensile strength of composite and fiber-matrix interface quality. The alkali treatment has less effect to the tensile strength than of the volume fraction gain and the void content. Composite manufacturing by hot press has a significant effect to the improvement of tensile strength up to 37% compare to the hand lay-up method. Water absorption up to 8.8% had decreased the tensile strength of composites up to 29%. The alkali treatment on the bamboo fibers had effectively reduced water absorption into the composite as well as the tensile strength reduction.
Effect of Temperature on Corrosion behavior of Copper Silver Phosphorus Brazing Alloys in Chloride Containing Solution
Authors: Prajatelistia Ekavianty , Nurrochman Andrieanto , Kyehyun Cho
Published: September 2019

The groups of phosphorus-containing brazing alloys are the most favored filler metals used for joining copper and copper-base alloys. These brazing alloys are expected to have the optimum corrosion resistance during the application. However, failures arise at the braze joint generally caused and initiated by the corrosion of the brazing alloys when used at higher temperature than the room temperature. Since most studies of the phosphorus containing brazing alloys were performed at room temperature, this work has been extended to investigate the effect of various temperature on the corrosion behavior. Electrochemical measurements were carried out to observed the temperature effect with the temperature variation of 25, 40, 55 and 70 °C in 3.5% NaCl electrolyte. As the results, the copper-silver-phosphorus brazing alloy was undergone a selective dissolution by the attack of Cl-to the copper element. The temperature dependence of the alloy showed in agreement with the relationship of 2.3RT/F that have similar manner on pure copper tafel region. The schematic diagrams of the corrosion process were then proposed. This work could be helpful to understand in the field practically because the application temperature is usually higher than that of room temperature in general.
Study to Enhance Tantalum and Niobium Contents in Bangka Tin Slag by NaOH and HClO4 Leaching
Authors: Vincia Shiva F , Permana Sulaksana , Maksum Ahmad , Soedarsono Johny W , Widana Kurnia S , Trinopiawan Kurnia , Munir Badrul
Published: September 2019

Indonesia is rich in tin ores. Slags from processing of tin ores naturally contain substantial amount of valuable metals, in this case tiobium and tantalum. This research explores how niobium and tantalum contents in local Bangka tin slag can be enhanced using NaOH and HClO4leaching reagents. First, Bangka tin slag was NaOH-leached and, then, the slag underwent HClO4leaching. Before undergoing any processes, the contents of niobium and tantalum in Bangka tin slag were 0.47% and 0.23%, respectively. After passing two leaching processes, niobium and tantalum contents reached 1.28% and 0.79%, respectively.
Enrichment of Tantalum and Niobium Contents in Bangka Tin Slag by NaOH and H3PO4Leaching
Authors: Akli Hendri F , Permana Sulaksana , Maksum Ahmad , Soedarsono Johny W , Widana Kurnia S , Anggraini Mutia , Munir Badrul
Published: September 2019

This study explores how 0.23% tantalum and 0.47% niobium in tin slag from the Bangka-Belitung archipelago, Indonesia, are upgraded. To enrich the contents of both metals, this research involves 8M NaOH leaching followed by 0.5M, 1M, and 1.5M phosphoric acid. First, tin slag was roasted at 900°C for 2 hours. Then, the sample was NaOH-leached while H3PO4 was exploited to leach its residues. Next, each of the residues from the leaching processes was characterized by XRF while the filtrates characterization used AAS and ICP-OES. On the one hand, NaOH leaching has proven to decrease the contents of iron, calcium, titanium, and aluminum. On the other hand, 0.5 M H3PO4 leaching optimizes tantalum contents up to 0.85% while 1.0 M H3PO4 leaching maximizes niobium contents up to 1.45%.
Effects of Austempering Process to Mechanical Properties of Thin Wall Ductile Iron Connecting Rod.
Authors: Sulamet-Ariobimo R.D. , Fadlan M. , Kamili S. , Sukarnoto T. , Mujalis Y. , Oktaviano Y.
Published: September 2019

Austempering process was carried out on thin wall ductile iron (TWDI) connecting rod produced by the design built in previous research. Austempering process was applied to improve the mechanical properties of the component, so it will be equal to forged steel. The aim of this work is to study the effects of austempering holding time to microstructure and mechanical properties of TWDI connecting rod. The process was applied to all connecting rods resulting from the vertical casting. The austenitising temperature was 960°C with 35 minutes holding time and the austempering temperature was 350°C with varied austempering holding time, that were 15, 30, 45 and 60 minutes. The process was held in fluidized bed furnace. Metallographic examination, tensile and compression stress-strain test were conducted directly to the connecting rod. The results showed that austempering process improved the mechanical properties of TWDI connecting rod and the result of the compression stress-strain test showed that the austempered TWDI connecting rod met its requirements.
The Role Of Annealing On Biodegradation Behavior Of Mg-Zn-Ca Alloy Prepared From Commercial Mg Sacrificial Anode
Authors: Setiawan Asep Ridwan , Basuki Arif
Published: September 2019

Magnesium and its alloys offers great potential application for biodegradable implant due to its low corrosion resistance, high biocompatibility, favorable mechanical properties, and young modulus similar to bone. However, there are still many challenges to be solved. In this work, Mg-Zn-Ca alloy were prepared from commercial Mg sacrificial anode, Mg-Ca master alloy, and pure Zn (99%) through casting process. Melting and alloying operations were conducted in a graphite crucible, using a home made melting facility. The influence of annealing treatment on the alloys performance were studied. Microstructure observations of the alloys were conducted using optical and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. The microhardness of the alloys were evaluated using Brinell hardness indentation. In vitro biodegradation behaviors of Mg-Zn-Ca alloy were evaluated through immersion test in Ringer Laktat solution. The results show that Mg-Zn-Ca alloy fabricated in our work exhibit minimum corrosion rates. Annealing treatment at 300 °C (8 hour, air cooling) alter the microstructure of Mg-Zn-Ca alloy. The microhardness of Mg-Zn-Ca alloys slightly increased from 43 (as cast) to 53 BHN (as annealed). The corrosion rate of the alloys was increased from 8 mm/year (as cast) to 17 mm/year (as annealed). This is suspected due to grain refinement and extensive formation of needle structures causing anodic couples with the matrix.
Effect of Annealing Cycle on Drawability and Microstructure of Cold Rolled Steel Sheet
Authors: Muda Iskandar , Dunne Druce P
Published: September 2019

The effect of the annealing cycle on microstructure, mechanical properties and draw ability of aluminium killed steel sheets at three different heating rates and holding times were investigated. Tensile test, hardness test, optical microscope and transmission electron microscope (TEM) techniques were utilized. The results of samples for different times in laboratory experiments were compared with the production samples. The results for these experiments showed that lower heating rates (12 °C/h) occurred at a lower annealing temperature, increase draw ability. This effect is attributable to the longer time available to initiate nucleation at the lowest heating rate. However, for all three heating rates (12 °C/h, 24 °C/h and 36 °C/h), the aluminium and nitrogen combine to form atmospheres or pre-precipitation clusters at polygonised sub-grains and as rolled boundaries, modifying the development of the recrystallized structure. Different amounts of AlN were precipitated prior to recrystallization for each heating rate resulting in different final recrystallized grain sizes, mechanical properties and drawabilities. The heating rate strongly influences recrystallization and drawability with a lower heating rate reducing both the temperature of the start of recrystallization and the recrystallized grain size. It is inferred that the lower rate promotes nucleation of recrystallization overgrowth of recrystallized. The effect of holding time on mechanical properties was to: (i) decrease tensile strength, yield strength and hardness and (ii) increase drawability, elongation and grain size. Tensile strength and hardness results from laboratory experiments were lower than those for production samples, but the trends were similar.
Failure Analysis of Blade on Coconut Shell Crusher Machine
Authors: Surasno  , Ihlas Apriardi
Published: September 2019

Blade mounted on coconut shell crusher machine was frequently having damaged while being operated in making of coconut shell powder at small and medium industries. This took place repeatedly during the operation, therefore blade repairing and replacement has to be done for every 16 hours at the wear rate of 24.28%. A research was carried out to find out the cause of damage to the metal blade material on the coconut shell crusher machine. The scope of this research included the observation on visual examination, dimensions examination, chemical composition, hardness, and metallography. The results of observations and tests showed that blade was broken due to abrasion and deformation during operation. The metal material used for the blade was low carbon steel. Chemical composition of the metal content of the blade were: C (0.103 up to 0.144 %) and Mn (0.657 up to 1.400 %). Hardness value of blade metal materials were 146 up to 148 Hv. Microstructure consisted of ferrite and pearlite. This low carbon steel material is not suitable to be used as a blade on coconut shell crusher machines for producing of coconut shell. Repairing and maintenance of welding coating methods on blades using low carbon electrodes does not give increased significant value of hardness. Blade replacement in coconut shell crusher machines must comply with the requirements of tool steel with suitable heat treatment or the use of low carbon steel with the carburization process.
Choice, Expectations, and the Placebo Effect for Sleep Difficulty
Authors: Yeung Valerie , Sharpe Louise , Geers Andrew , Colagiuri Ben
Published: September 2019

Background

Choice has been found to facilitate placebo effects for single-session treatments where standard placebo treatment without choice failed to elicit a placebo effect. However, it is unknown whether choice can enhance the placebo effect for treatments occurring over a period of days and where placebo effects are readily established without choice.

Purpose

We tested whether single or daily choice between two (placebo) treatments enhanced the placebo effect for sleep difficulty relative to no choice and no treatment over a 1 week period.

Methods

One-hundred and seventeen volunteers self-identifying with sleep difficulty were recruited under the guise of a hypnotic trial and randomized to one of the four groups. Self-reported outcomes included insomnia severity, fatigue, total sleep time (TST), sleep onset latency (SOL), perceived sleep quality (PSQ), and treatment satisfaction. Objective TST and SOL were assessed in a subsample via actigraphy.

Results

Overall, placebo treatment significantly improved insomnia severity, fatigue, and PSQ, confirming a placebo effect on these outcomes. However, both traditional and Bayesian analysis indicated no benefit of choice on the placebo effect on any sleep outcome. Mediation analysis of the overall placebo effect indicated that expectancy completely mediated the placebo effects for insomnia severity and PSQ and partially mediated the placebo effect for fatigue.

Conclusion

These findings suggest that choice does not enhance the placebo effect over longer treatment periods (up to 7 days) when placebo effects are readily established without choice. As such, any benefit of choice on placebo effects may be confined to quite specific circumstances.

Clinical Trials Registration

ACTRN12618001199202.
Estimating the Intracluster Correlation Coefficient for the Clinical Sign “Trachomatous Inflammation—Follicular” in Population-Based Trachoma Prevalence Surveys: Results From a Meta-Regression Analysis of 261 Standardized Preintervention Surveys Carried Out in Ethiopia, Mozambique, and Nigeria
Authors: Macleod Colin K , Bailey Robin L , Dejene Michael , Shafi Oumer , Kebede Biruck , Negussu Nebiyu , Mpyet Caleb , Olobio Nicholas , Alada Joel , Abdala Mariamo , Willis Rebecca , Hayes Richard , Solomon Anthony W
Published: September 2019

Sample sizes in cluster surveys must be greater than those in surveys using simple random sampling in order to obtain similarly precise prevalence estimates, because results from subjects examined in the same cluster cannot be assumed to be independent. Therefore, a crucial aspect of cluster sampling is estimation of the intracluster correlation coefficient (ρ): the degree of relatedness of outcomes in a given cluster, defined as the proportion of total variance accounted for by between-cluster variation. In infectious disease epidemiology, this coefficient is related to transmission patterns and the natural history of infection; its value also depends on particulars of survey design. Estimation of ρ is often difficult due to the lack of comparable survey data with which to calculate summary estimates. Here we use a parametric bootstrap model to estimate ρ for the ocular clinical sign “trachomatous inflammation—follicular” (TF) among children aged 1–9 years within population-based trachoma prevalence surveys. We present results from a meta-regression analysis of data from 261 such surveys completed using standardized methods in Ethiopia, Mozambique, and Nigeria in 2012–2015. Consistent with the underlying theory, we found that ρ increased with increasing overall TF prevalence and smaller numbers of children examined per cluster. Estimates of ρ for TF were independently higher in Ethiopia than in the other countries.
Visual and Olfactory Attributes of Artificial Nests
Authors: Rangen Sheila A. , Clark Robert G. , Hobson Keith A.
Published: September 2019

Artificial nests are commonly used to investigate relative rates of nest predation in birds, but several methodological considerations need to be addressed before results from natural and artificial nests can be compared. Using field and laboratory experiments, we examined responses of predators to visual and olfactory cues that were associated with wicker nests and their contents. Avian predators did not discriminate between wicker nests dipped in mud and those covered by a camouflage fabric, whereas mammalian predators showed a weak tendency to depredate camouflaged nests. Nests containing plasticine eggs were depredated more often than nests containing only quail eggs and finch eggs, although no response to number of plasticine eggs in nests was found. The higher predation of nests with plasticine eggs may have resulted because small mammals, relying on olfactory cues, comprised a large portion of the predator assemblage. Field results were supported in tests where captive deer mice (Peromyscus maniculatus) were attracted to assortments of egg types that included plasticine. Time required by captive deer mice to penetrate quail eggs and finch eggs versus plasticine eggs varied as a function of egg size and shell thickness and strength. Overall, domestic finch eggs provided a better alternative to quail eggs because they were small enough to allow detection of predation events by small mammals and did not have an unnatural odor like plasticine. Potential problems with nest concealment, egg visibility, egg odors, and other factors must be resolved to enhance the design and reliability of artificial nest experiments.
Fledging Success as an Index of Recruitment in Red-Winged Blackbirds
Authors: Weatherhead Patrick J. , Dufour Kevin W.
Published: September 2019

We used data from an 11-year study of Red-winged Blackbirds (Agelaius phoeniceus) to test the hypothesis that fledging success is a reliable index of recruitment at the population and the individual level. Natal philopatry was only 2.37% overall (3.51% for males and 1.49% for females) in our study population. However, the number of fledglings that returned as breeding adults from an annual fledgling cohort was significantly correlated with the size of the cohort. The correlation was also significant when males and females were analyzed separately, despite sex differences in natal philopatry, age of first breeding, and probable differences in mortality factors. Recruitment increased disproportionately with the size of the fledgling cohort. Thus, years of high production produced proportionately more breeding adults. At the individual level, the number of fledglings sired by a male in his lifetime was significantly correlated with the number of his descendants that eventually returned to breed in the study population. These results support the widely held assumption in avian field studies that fledging success is a reliable index of fitness.
Observational Learning in Hummingbirds
Authors: Altshuler Douglas L. , Nunn Andrea M.
Published: September 2019

Migratory hummingbirds forage on diverse assemblages of flowers varying in shape, color, and accessibility. Do hummingbirds learn to feed from flowers by observing other hummingbirds? Learning abilities of Ruby-throated (Archilochus colubris), Broad-tailed (Selasphorus platycercus), and Rufous (S. rufus) hummingbirds were studied in the presence or absence of a knowledgeable tutor. In two sequential trials hummingbirds learned to feed from artificial feeders of increasing complexity. Feeders in the first trial had easy access and were colored red at the nectar spout. In this initial trial, hummingbirds attempted to feed from the artificial feeder regardless of tutor presence, but tutored birds learn to feed more quickly. Feeders in the second trial were uncolored and the nectar spout was surrounded by a long artificial corolla. Tutored birds again learned to feed more quickly than their solitary counterparts. However, both untutored and tutored hummingbirds learned to feed more quickly in the second trial than the first, suggesting that the initial task of identifying a novel feeding resource is more difficult than learning how to access an identified resource.
Evidence of Differential Migration by Sex in White-Throated Sparrows (Zonotrichia Albicollis)
Authors: Jenkins Kendell D. , Cristol Daniel A.
Published: September 2019

Differential migrants are species in which one population class migrates farther than another. White-throated sparrows (Zonotrichia albicollis), which migrate into the southern United States each autumn in large numbers, have been proposed as a candidate differential migrant (Cristol et al. 1999). Using Bird Banding Lab data, we tested for latitudinal variation in the sex ratio of White-throated Sparrows in the Atlantic and central flyways. We found that the proportion of females increases with decreasing latitude in at least the Atlantic flyway, strongly suggesting that females migrate farther than males. Sex ratios calculated from those banding data were compared to those of museum specimens collected at the same latitudes, as well as single-season population samples at three latitudes in the heart of the winter range. Broad agreement was found using the three independent methods of sampling the sex ratio, so we conclude that White-throated Sparrows are differential migrants.
Stories Less Told: Parenting Strengths and Family-of-Origin Experiences amongst Parents Involved with Child Protective Services
Authors: Yoo Hana , Abiera Kelsey
Published: September 2019

Strengths-based child welfare practice emphasises the importance of acknowledging clients’ capacities and potentials when addressing their presenting issues of child maltreatment. However, the child welfare literature has focused more on parents’ risk factors and deficits whilst giving limited attention to positive parenting practices that they may have employed. Based on semi-structured interviews with parents involved with child protective services (CPS), this study explored these parents’ self-identified parenting strengths in light of their family-of-origin experiences. Results of interpretative phenomenological analysis (IPA) revealed that participants identified parenting strengths in the areas of provision, protection, emotional care and relational support, and parental guidance and discipline. All demonstrated a strong desire to provide their children with a better upbringing than their own and shared what they believed they had done well in parenting. Interestingly, participants seemed to have parented most intentionally in the areas in which they felt most deprived in their own childhood, which may have played a role in creating deficits in other areas of parenting. Implications for practice include the need for a ‘both/and’ approach that attends to parents’ strengths as well as areas for growth and the importance of family-of-origin work in child welfare practice.
Care Leavers and Children’s Services: Exploring the Utility of Communities of Practice in Theorising Transition
Authors: Turner Lynda , Percy-Smith Barry
Published: September 2019

This article considers the application of Communities of Practice theory to understand transition into, through and out of care, arguing that a sense of belonging and identity emerges from participation in supportive communities. We consider the influence of community on looked after children and care leavers’ sense of identity, engagement and well-being in transition. We also focus on the ways in which service policy and provision shapes professional practice. In doing so, we move beyond the argument for supportive relationships to examine some of the practices which mediate the interpersonal and reflect on the need to understand the meanings of disengagement. We discuss some of the ways practices within and across different communities affect young people’s trajectories and professionals’ responses, such as developing resilience, preparation for leaving care and achieving independence. Whilst current policy and provision focuses on preparation for independence, the article claims that resilience emerges through community and considers the importance of developing supportive social ecologies for cared for children to sustain them in their transition from care. It also calls for an examination of assumptions of accountability and measurement in policy and the importance of hearing the voices of professionals and developing dynamic and responsive practices.