bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave Synthesis and Photocatalytic Activity of Ce4+, Fe3+ Co-Doped TiO2 Nanocomposite
Authors: Xiong Wan Qing , Zhu Quan Xin , Lei Jian , Ye Wen Xiang , Liao Xue Hong
Published: October 2013

In this paper, Ce4+and Fe3+co-doped titanium dioxide nanocomposite was prepared by iron nitrate, cerium sulfate and titanium sulfate as raw materials and sodium dodecyl sulfate as surfactant under microwave irradiation. The x-ray diffraction (XRD) results show that as-prepared sample of direct adding doped cerium and iron content were 0.2% and 0.5% of titanium sulfate amount of substance calcined at 500°C for 2 h is anatase. We also studied the photocatalytic activity of the as-prepared Fe3+and Ce4+co-doped TiO2nanocomposite by using degradation of methyl orange solution. The effect conditions of photo-catalytic activities of the composite were investigated, such as different ratios of direct adding doped iron and cerium content, different dosage of hydrogen peroxide, different pH value, and different dosage of nanocomposite. When the catalyst is 1.0 g/L, pH value is 4.3, C(H2O2) is 3 mL/L, the effect of the visible light catalytic activity was the best, in 20 min, the degradation rate of 20 mg/L methyl orange solution was more than 90%. Obviously, as-prepared Fe3+and Ce4+co-doped titanium dioxide nanocomposite as photocatalysts for degradation methyl orange, has a significant effect. Moreover, the operation was simple, and there was no secondary pollution. In a word, it has a good prospect.
Ti3SiC2 – A New High Temperature Solid Self-Lubricating Additive Agent
Authors: Li Li Xin , Liu Xue Quan , Ding Cun Guang , Li Yi , Li Fa Chang , Li Jin Pu
Published: October 2013

With the additive agent Ti3SiC2, the dry sliding behavior of Cr3C2-Ni and Cr3C2-Ni-Ti3SiC2 composites against GCr15 was investigated with a pin-on-disk tester at 400 °C in air under the load of 200N. Without Ti3SiC2, the dynamic coefficient of friction (COF) curves was fluctuated severely. After adding Ti3SiC2, the COF was decreased from 0.37 to 0.32, and the initial transition region of dynamic COF curve was shortened. These tribological test results showed that Ti3SiC2 was a new kind of solid additive agent with favorable high temperature self-lubricating property, and two possible mechanisms was proposed for its anti-friction ability.
The Creep Behavior of Wood-Polymer Composites
Authors: Zhu Yuan , Liu Pei Ying , Jiang Zhi Hong
Published: October 2013

The creep behavior of WPCs needs to be addressed when developing and using this kind of materials. In this paper, the creep behavior of WPCs under linear viscoelastic region was investigated at different temperatures and bamboo flours levels. The creep compliance increase with the rise of temperature, the addition of bamboo flour has a positive effect on the creep behavior. Burgers model, Findley power law and TTSP were used to predict the long-term behavior of this kind material. Finely power law can well describe the creep properties of WPCs while Burgers model begins to diverge from measured data at about 100min. The application of TTSP was used to create master curve covered more than 108 from 30-min short-term creep compliance curves.
Blue-Green Mechanoluminescence of CaAl2Si2O8:Eu2+ and CaAl2Si2O8:Eu2+,Dy3+
Authors: Chu Zhen Ming , Li Yan Xia , Wang Xu Sheng , Yao Xi
Published: October 2013

This paper studied the mechanoluminescence of the CaAl2Si2O8:Eu2+x, Dy3+y phosphors. The crystal structure, photoluminescence (PL) and mechanoluminescent intensity of the phosphors were investigated. The emission peak of CaAl2Si2O8: Eux2+ had a redshift from 418 nm to 428 nm due to the increase of the crystal filed intensity around Eu2+ with the increase of Eu2+ ion content. The ML (mechanoluminescence) emission of CaAl2Si2O8:Eu0.01and CaAl2Si2O8:Eu2+0.01, Dy3+0.02 can be seen by the naked eyeswhen compressive loads were appliedon the samples. Whats more, the addition of Dy3+can increase the ML intensity of CaAl2Si2O8:Eu0.01. The ML and PL spectra of the sample CaAl2Si2O8:Eu2+0.01, Dy3+0.02 are identical, located at 428 nm.
Study on Laser Welding of Phone Nuts
Authors: Wu Xiao Hong
Published: October 2013

Used YAG pulse laser to weld 304 stainless steel nuts, studied about the parameters such as peak power, pulse width, defocus distance impacting on the performance of the joints welded by laser. The studies showed that the tensile strength and torque of the nuts increased as the peak power and the pulse width increased.Burn through in welding easy occur when laser pulse energy is too big, pulse width is too wide or defocus distance is too low.
A Research on the Device of Manufacturing Metal Powder
Authors: Luo Feng
Published: October 2013

The atomization mechanism here makes full use of the comprehensive effects of the centrifugal atomization, the oscillating atomization and the impact breakage atomization, synthesizing the superiorities of the three as an organic and powerfully efficient whole, and making their mutual reactions stronger step by step. The impact breakage atomization is a new auxiliary mechanism among the three, which can improve the atomizing process of droplets considerably after the centrifugal and the oscillating atomization, producing much better an atomizing result. It is very convenient, simple and direct to fulfill the three-in-one.
Study on Pretreatment Method of X-Ray Real-Time Imaging Digital Image
Authors: Zhang Peng Lin , Zhao Zhi Qiang , Kong Peng
Published: October 2013

X-ray nondestructive testing has a wide range of applications, which in materials testing, food testing, manufacturing, instrumentation, automotive parts and other fields having good performance. The paper mainly deals with low contrast X-ray digital images, image edge blur features and digital image preprocessing techniques of contrast. By a crack image taking geometric transformations, gray-scale transformations and image enhancement processing such as pretreatment technology airspace transforms, getting three options that have been able to effectively realize image denoising and enhancement. These three sets of processing solutions, to some extened, opening the image intensity distribution and making cracks sharper image segmentation is the foundation of subsequentence.
Predictive Modeling of Oxide Layer Thickness in Ultrasonic-ELID Multiplicate Grinding
Authors: Jia Xiao Feng , Zhao Bo , Bian Ping Yan
Published: October 2013

The oxide layer formed and removed on the surface of the grinding wheel has a significant influence on the grinding quality of ultrasonic-ELID multiplicate grinding. In this paper on the basis of the principles of electrochemical and ultrasonic vibration, the mechanisms of oxide layer formation and remotion were analyzed. Then, the predictive modeling of oxide layer thickness was proposed. The effects of main factors on the oxide film thickness were simulated and analyzed theoretically. The simulation results show that the layer thickness decreases with the decrease of the duty ratio or the grain volume ratio or the ultrasonic frequency ,and the increase of the electrode gap during the composite grinding process.
The Numerical Simulation and Finite-Element Analysis of the Motor Vibration Problem Based on the Base Anchor Softening Layer
Authors: Gu Yu , Li Shao Xiong , Li Rui , Li Qiang
Published: October 2013

Vibration results from situation when the inherent frequency close to the external exciting force during the operation of the motor, so accurate and effective calculation of the natural frequency of the motor has an important significance to damping noise. By numerical simulation model and the ANSYS finite element modal, the inherent frequencies were got of the motor and comparison results verify the effectiveness of the motor model. The effect of the modulus of elasticity of the softening layer between the motor and the ground to the inherent frequency was researched intensively, and puts forward related suggestions.
Direction Finding of Multiple Coherent Signals Based on Frequency Domain Sample Process
Authors: Zhu Xue Guang
Published: October 2013

In the field of communication direction finding by using antenna array, multi path effect arouses great attention. It not only increases the number of arriving waves, but the multi arriving signals are coherent. In order to solve the problem brought by multi path effect, much more elements are needed for multi arrival direction estimation after cancelling coherence processing which also requires more elements by spatial smoothing method. The method of frequency domain process is used in this paper to reduce the coherence between signals. The principal reason is that there is various wave distance difference between the multi arriving waves. The phase lag is not the same for different arriving path. Therefore we can adopt wide band receive process. The spatial vectors for different frequency component are not coherent, so it needs less elements for the array in the same case. The simulation results prove it is practical.
Biomediated Separation of Kaolinite and Hematite Using Bacillus subtilis
Authors: Poorni S. , Natarajan K.A.
Published: October 2013

Bacillus subtilis was used to demonstrate microbially induced selective flocculation to separate kaolinite and hematite. In neutral pH range of 7 - 8, 90 - 95% of hematite was selectively flocculated whereas 80 - 85% of kaolinite was dispersed using hematite - grown cells. Hematite- grown cells exhibited significant adsorption onto hematite than onto kaolinite, compared to unadapted cells. Kaolinite grown Bacillus subtilis secreted significant amounts of mineral specific proteins which conferred surface hydrophobicity whereas hematite-grown cells secreted more polysaccharides rendering hematite hydrophilic. Bacterial extracellular protein (EP) was isolated and the protein profiles of bacteria grown in the absence and presence of minerals were established.
A Descriptive Model for Microbial Population Dynamics in a Copper Sulphide Bioleaching Heap with Spatial and Physicochemical Considerations
Authors: Soto-Rojo Susana , Glonek Gary , Soto Pamela , Demergasso Cecilia , Solomon Patty
Published: October 2013

A descriptive mathematical model is a valuable tool that can help understand the relationship between the heap leaching process at the Escondida mine in Chile, the microbial community that participates in the process, and the physical characteristics of the heap, such as the arrangement and the mineral composition of the individual leaching strips. However, the bioleaching process at Escondida is a system, which presents many challenges to modelling. The main challenges relate to heap's design and mineral characteristics, the complex interactions between biological and physicochemical parameters, and the unexpected changes in the heap's operational conditions. The heap is sampled periodically and more than 20 variables, including 16S rRNA gene copy number for 16 different microorganisms, are recorded. The data exhibit complex behaviour, including variable dynamics between strips, systematic differences between lifts of the heap, and spatial and temporal correlations. In this work, we develop a non-linear descriptive model for the microbial population trajectory along the leaching cycle and across the different strips. The parameterisation of the model considers the different dynamics between lifts, and strip specific parameters characterise the behaviour of data from individual strips. The parameterisation also allows for spatial correlation by incorporating the effect of adjacent strips on the microbial population trajectory. The model is found to provide a good fit to the data and captures its behaviour across strips. Residuals showed no systematic patterns of departure between the observed and modelled response. The R2 values ranged from 0.53 to 0.71, indicating a reasonable level of predictive power.
Bioleaching of Phosphorus from Low Grade Ores and Concentrates with Acidophilic Iron- and Sulphur-Oxidizing Bacteria
Authors: Sarlin Tuija H. , Priha Outi K. , Arnold Mona E. , Kinnunen Päivi
Published: October 2013

Bioleaching experiments of phosphorus from low grade fluorapatite ore containing 8.2% P2O5 and from fluorapatite concentrate containing 29.8% P2O5 were carried out in shake flasks. Elemental sulphur was supplemented as an energy source for acid generation. Mixed and pure acidophilic bacterial cultures consisting of iron-and/or sulphur-oxidizing bacteria Acidithiobacillus ferrooxidans, A. thiooxidans and Leptospirillum ferrooxidans were used in the experiments. These acidophiles are commonly used in bioleaching of sulphide minerals, but their application on phosphorus bioleaching has been limited. Phosphorus leaching was shown to be a pH-dependant phenomenon. Phosphorus leaching yields of up to 97% and 28% were obtained in 3 weeks for low grade fluorapatite ore and concentrate, respectively. These results indicate a potential for applying bioleaching for phosphorus extraction from low grade materials.
Two-Step Bioleaching and Spent Medium Leaching of Gold from Electronic Scrap Material Using Chromobacterium violaceum
Authors: Natrajan Gayathri , Ting Yen Peng
Published: October 2013

Rapid technological advancement and the relatively short life time of electronic goods have resulted in an alarming growth rate of electronic waste which often contains significant quantities of toxic and precious metals. Compared to conventional chemical recovery methods, bioleaching has been shown to be an environmentally friendly process for metal extraction. In this work, gold bioleaching from electronic scrap material (ESM) was examined using batch cultures of the bacterium Chromobacterium violaceum which produces cyanide as a secondary metabolite. Gold was bioleached via gold cyanide complexation. The ESM was pretreated using nitric acid to dissolve the base metals (mainly copper) in order to reduce competition for the cyanide ion from other metals present in ESM. ESM was added to the bacterial culture after it reached maximum cyanide production during early stationary phase. Spent medium bioleaching using bacterial cell- free metabolites showed a higher gold recovery of 18%, compared to that of two-step bioleaching of 11% at 0.5% w/v pulp density of ESM. Gold bioleaching was further enhanced to 30% when the pH of the spent medium was increased to shift the equilibrium in favor of cyanide ions production. Spent medium bioleaching of pretreated ESM yield a higher gold recovery compared to two-step bioleaching at a pulp density of 0.5% w/v.
Bioprocessing of Mining and Metallurgical Wastes Containing Non-Ferrous and Precious Metals
Authors: Bulaev Aleksander , Muravyov Maxim I. , Pivovarova Tatyana , Fomchenko Natalya V. , Kondrat'eva Tamara F.
Published: October 2013

Mining and metallurgical treatments of sulphide ores are characterised by present significant losses of non-ferrous and precious metals as different types of waste. These elements are accumulated in heaps due to the lack of efficient technology for the recovery of the metals from metallurgical waste. The treatment of two types of industrial metallurgical waste (copper converter slag and old flotation pyrite tailings) containing non-ferrous and precious metals were examined in the laboratory. Leaching of the slag containing 2.74% Cu (as digenite, bornite, and free metal) and 2.49% Zn (as a ferrite ZnFe2O4 and silicate) by an Fe3+-containing solution was studied. The effect of various experimental parameters on the leaching dynamics of copper, zinc, and iron under batch conditions was investigated. The following experimental parameters were recommended: a pH of 1.5, a pulp density of 10% (w/v), a temperature of 70 °C, and an initial Fe3+ concentration of 15 g/L. Leaching under these conditions resulted in the solubilisation of 89.4% copper and 35.3% zinc within 2.5 hours. Percolation leaching of the pyrite tailings containing 0.29% Cu (as chalcopyrite), 0.26% Zn (as sphalerite), 0.00007% gold, and 0.00108% silver was also studied. Acidic percolation leaching and the resulting biooxidation lasting 134 days resulted in the solubilisation of 73.4% zinc and 50.8% copper. The recovery rates of gold and silver from the bioleaching residues by cyanidation were 57.2% and 50.7%, respectively. The data obtained in the present work may be used to estimate the operating parameters for the industrial-scale processing of non-ferrous and precious metals from mining and metallurgical waste.
Biotransformation of Arsenopyrite by Phanerochaete chrysosporium
Authors: Liu Qian , Yang Hong Ying , Qiao Li Li
Published: October 2013

Abstract. In this study, the arsenopyrite was used as representative of gold-bearing sulfides in Carlin-Type gold ores to test the ability of oxidation on them by P. chrysosporium. After shaking incubation for 20 days, the conversion rates of iron, sulfur and arsenic in arsenopyrite were 6.28%, 35% and 21.76%, which were 44.86, 2.98 and 48.36 times compared with the asepsis system, respectively. It indicated that the P. chrysosporium could improve obviously the biotransformation rate of arsenopyrite by its own metabolic activity. The electrochemical oxidation behavior of arsenopyrite in the leaching system without and with P. chrysosporium were detected with electrochemical technology. The results showed that the P. chrysosporium did not change the oxidation mechanism of arsenopyrite, but strong oxidizing environment, which was structured by its products-oxidative enzymes and hydrogen peroxide, could promote the transformation from Fe2+ to Fe3+. P. chrysosporium could significantly decrease pitting potential and improve polarization current of arsenopyrite electrode and then accelerate its corrosion process. These indicated that P. chrysosporium was an available microorganism for degrading and transforming sulfides. P. chrysosporium could break gold inclusion and improve gold leaching rate, and finally realized economical and efficient application of Carlin-type gold ores.
Effect of Contact with Organic Extractant LIX 84IC during Solvent Extraction Process on the Re-Establishment of Growth of Bioleaching Microorganisms
Authors: Davis-Belmar Carol S. , Acosta Mauricio , Schoen Valerie , Rautenbach George , Demergasso Cecilia
Published: October 2013

Solvent extraction (SX) used for the recovery of copper is a primary low-cost hydrometallurgical process applied extensively in cases like commercial bioleaching operations. Bioleaching solutions during SX treatment are exposed to important concentrations of organic extractants, a step that has a detrimental impact on microbial activity. The following work studies and determines the effect of this exposure on the re-establishment of growth and activity of different bioleaching microorganisms after contact and phase separation. Different bioleaching iron and sulfur -oxidizing microorganisms were tested. After contact with an industrially utilized organic extractant (LIX 84IC as extractant and Oxform SX12 as solvent), cultures were grown and their substrate utilization monitored.Acidithiobacillus ferrooxidansshowed only a slight increase in doubling time without significant latency period. On the contrary, for bothSulfobacillusspecies studied,S. thermosulfidooxidansandS. thermotolerans, were strongly impacted showing important lag phases before growth could take place. Additionally, the SX reagent showed disruption of cell walls and protein liberation during contact with all the different strains studied.
Effect of Bio-Leaching Process on the Pore Structure of Packed Particle Bed via 3D Imaging and Analysis
Authors: Wu Ai Xiang , Yang Bao Hua , Liu Jin Zhi , Miao Xiu Xiu
Published: October 2013

Heap bio-leaching technology is extensively applied to recover metals from low-grade complex ores in the mining industry, particularly the copper sulfide ores. Understanding the effect of bio-leaching process on the pore structure of packed particle beds is important to enhance the percolation and leaching performances with respect to design and operation of heap leaching system. The porosity, pore size distribution and degree of pore connectivity are the three most important features correlated with fluid flow in heap leaching operation. In this study, a spiral X-ray CT scanner, combined with 3D imaging and analysis, was used to characterize the complex pore structure of the packed ore particle beds before and after bioleaching copper sulfide ores. The results indicate that the pore structure has temporal and spatial variations during bio-leaching process.
Evaluation of the Electrochemical Behavior of Carbon Paste Electrode (CPE) with Chalcopyrite (CuFeS2) in the Presence of Ferrous Ions
Authors: Arena Fabiana A. , Bevilaqua Denise , Fujivara Cecilio S. , Benedetti Assis V.
Published: October 2013

In this work we present an electrochemical study using carbon paste electrode (CPE) with CuFeS2in solutions with different concentrations of Fe2+ions in order to evaluate the possible interaction between these ions and mineral sulfide in the absence and presence of the bacteriaAcidithiobacillus ferroxidans.
Investigation of Bioleaching of a Low Grade Nickel-Cobalt-Copper Sulfide Ore with High Magnesium as Olivine and Serpentine from Lao
Authors: Chen Bo Wei , Cai Liu Lu , Wu Biao , Liu Xue , Wen Jian Kang
Published: October 2013

Shake flask bioleaching of a low-grade nickel-cobalt-copper sulfide ore from Lao was investigated to test the technical feasibility to recovery metals from this ore. The mineralogical results indicated that the valuable minerals were disseminated finely and the ore had a low content of sulfur and high content of iron and magnesium, which was very harmful for bioleaching. The effects of different parameters such as the amount of acid addition, inoculation volume, initial pH, temperature and leaching time on the bioleaching performance of the ore were evaluated after pre-leaching with dilute acid. The results showed that nickel, cobalt, copper leaching rates reached 81.61%, 80.75%, 70.97% at 33 °C and 83.40%, 82.13%, 70.34% at 45 °C. The mineralogical analysis of the leaching residues revealed that the leaching rate of nickel sulfide was more than 92% and the unleached nickel was mainly present as nickel silicate.
True Growth Rate Kinetics: An Account of the Colonisation and Transport of Microorganisms on Whole Low Grade Ore, at the Agglomerate Scale
Authors: Govender Elaine , Bryan Christopher G. , Harrison Susan
Published: October 2013

The quantification of microbial colonisation and growth rate kinetics is essential in the characterisation of bioleaching systems for modelling heap performance. An experimental system, designed to simulate heap bioleaching conditions at the agglomerate scale, was used to quantify the microbial growth kinetics of a pure culture of Acidithiobacillus ferrooxidans in the PLS, the interstitial phase and attached to the mineral ore. Conventional methods for the quantification of microbial growth rate kinetics associated with the ore and in the flowing PLS have been found to be inadequate in the characterisation of whole ore systems owing to microbial transport between these regions. Growth within the whole ore system was dominated by the microbial communities associated with the ore. Two models were used to estimate the true growth rate kinetics of Acidithiobacillus ferrooxidans on whole low grade ore as a function of growth and transport between the identified phases. The “hydrodynamics” model assumed that microbial transport was promoted by fluid flow dynamics whilst the “biomass balance” model assumed that the microbial concentration gradient across identified phases was the driving force for transport.
Effect of Fe2+ and Cu2+ Ions on the Electrochemical Behavior of Massive Chalcopyrite in Bioleaching System
Authors: Qin Wen Qing , Yang Cong Ren , Wang Jun , Zhang Yansheng , Jiao Fen , Zhao Hong Bo , Zhu Shan
Published: October 2013

The electrochemical behavior of massive chalcopyrite in presence of Acidithiobacillus caldus, Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans and Sulfobacillus thermosulfidooxidans has been studied by cyclic voltammetry. The effect of Fe2+ and Cu2+ ion addition on the electrochemical behavior of massive chalcopyrite in bioleaching system were also investigated. The voltammograms illustrated that current densities of peaks were obviously increased with adding Fe2+ into the electrolyte. A series of anodic peaks were observed at more than 0 V when adding Fe2+ and Cu2+ ions, and these peaks are similar to the peaks of the step oxidation of chalcocite, thus proving that the formation of intermediate CuS2. Especially, the 9 g/L Fe2+ and 1.5 g/L Cu2+ were added. Therefore, appropriate ferrous and cupric ions concentration could enhance the formation of intermediate CuS2 leading to accelerate dissolution of chalcopyrite.
Evaluation of Plant Species for Phytoremediation of a Mining Waste from Andacollo, Neuquén-Argentina
Authors: Cordero Cintia , Incignieri Karen , Chiacchiarini Patricia A. , Lavalle Teresa L. , Giaveno Alejandra
Published: October 2013

800x600 Mining waste disposal and treatment is one of the biggest environmental challenges that mining confront at present. A promising approach is the phytoremediation technology, where living plants are used to remove metals from impacted sites or to stabilize mine tailings. The aim of this work was to evaluate several plant species for phytoremediation of a mining waste from gold ores concentration plant in Andacollo, Neuquén-Argentina, to propose the execution of an environmental restoration plan in this area. For the forestation assays Pinus ponderosa, Pinus murrayana, Populus nigra species and a herbaceous plant, Festuca arundinacea, were selected. The tailings used in this study was physicochemically characterized and resulted to be non-potentially acid generating and presented very low organic matter and macronutrients contents. The sequential extraction showed that no metals were present in the water soluble fraction minimizing the risks of spreading heavy metals. Phytoremediation assay showed that all vegetable species could grow on the mine tailing. The dry vegetal biomass for F. arundinacea was only 28 % lower than the one obtained in the control soil. Pinus species and P. nigra presented high values of translocation factor only for Zn. These preliminary results suggest that the forestation of this tailing dam with Pinus species and F. arundinacea could be an adequate strategy to phytoremediate this particular area. Normal 0 21 false false false ES-AR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}
Visualization of Attachment and Colonization of Pyrite Surfaces by a Novel Species of Acidianus
Authors: Castro Camila , Vera Mario , Donati Edgardo , Sand Wolfgang
Published: October 2013

In this work we have studied the attachment and colonization of pyrite surfaces by the recently isolated thermophilic archaeon CandidatusAcidianus copahuensis(isolated from the geothermal Caviahue-Copahue system, Argentina). Cells pregrown with sulfur, iron (II) or pyrite were tested. In order to characterize the EPS glycoconjugates of this strain, fluorescent lectins were used. Concanavalin A (ConA) gave the best signal and was selected for further studies. Coupons and grains of pyrite were treated with DAPI (to stain attached cells) and TRITC-ConA (to stain polysaccharides from EPS). Pyrite surfaces were imaged by epifluorescence (EFM) and confocal laser microscopy (CLSM). Initial cell attachment to pyrite grains was estimated to be 26%, 35% and 43% when cells were pregrown with sulfur, iron (II) and pyrite as electron donors, respectively. It was observed that the cell adhesion correlated with an increase of EPS production; both processes were favoured when cells were pregrown with pyrite or iron (II). Also the effect of phosphate (Pi) starvation in the attachment ofAcidianuswas studied in similar tests using a base medium without Pi. An increase of cell attachment under Pistarvation conditions was detectable.
Norton Vitrium3 – Revolutionary Grain Adhesion
Authors: Kiss Sándor
Published: October 2013

Saint-Gobain Abrasives is one of the biggest abrasive product producers, owning brands like, Norton, Winter, BayState, Flexovit, Universal.
The Influence of Cutting Conditions on Surface Roughness during Steel X38CrMoV5 Grinding
Authors: Novák Martin , Naprstkova Natasa
Published: October 2013

Machining of tool steels is often an important used technology. Products made from these materials are often used in mechanical engineering, and quality of workpiece surface roughness after machining respective grinding is one of the important parameters that to us speak about the quality of the machining process. The paper deals with the influence of cutting conditions when grinding tool steel X38CrMoV5 (EN ISO) on machined surface roughness.
Integral Characteristics of Triangulation 3D Models of Products
Authors: Grabchenko Anatoly I. , Dobroskok Vladimir L. , Garashchenko Yaroslav N. , Abdurajimov Lenmar N.
Published: October 2013

The integral characteristics of triangulation 3D models of industrial products are considered. Absolute integral characteristics are presented by the following groups: linear, angular, surface and volume. For comparative evaluation the relative characteristics are proposed. The proposed integral characteristics are a component part of a morphological analysis system of 3D models.
Tool Profile Generation by Boolean Operations on Ball Nuts
Authors: Hegedűs György , Takács György
Published: October 2013

Ballscrew drive mechanisms are widely used in the transmitting system of precision machine tools. The profile of the ball nut is a gothic curve combined by two equal radius arcs with offset centers. Most of gothic arc ball nuts are manufactured by form grinding, where the grinding wheel is shaped into the desired profile and the tool axis is tilted at the lead angle of the ball nut thread. In case of the internal ball nut grinding the high lead angle and long thread limits the manufacturing process. To avoid the collision between the internal surface of the workpiece and outer surface of the quill the optimal tilt angle is modified. The modified tilt angle affects to the profile of the formed grinding wheel. This paper presents a method for the generation of modified grinding wheel profile independently the tilt angle. The desired profile points are generated by solid boolean operations with programming of a parametric CAD system.
Improvement of Working Capacity of Carbide Tools for Machining Rail Wheel Pairs
Authors: Vereschaka Anatoliy Stepanovich , Kulikov Mikhail Yu. , Vereschaka Alexey Anatolevich , Florov A.V. , Popov Alexey Yu. , Maung San
Published: October 2013

It was found out that under turning wheel pairs, complete tool failure occurs as a result of ductile fracture of cutting wedge. It was also found out that the process of ductile fracture of a tool is governed by creep of local volumes of tool material adjacent to tool contact areas caused by its severe thermo-mechanical load in machining of hard-drawn surfaces of wheel pairs. The method was proposed to effectively reduce thermo-mechanical load on tool contact areas under machining of wheel pairs, while improving heat transfer from the cutting zone, which provides reduction of thermal stress of cutting wedge and improvement of the efficiency of cutting tool.
Optimisation of Experimental Techniques to Enhance the Efficiency of Polymer Photovoltaic Cell
Authors: Sodhi P.S. , Sahare Sanjay , Kumar V. Naresh , Swarnkar A.K. , Jadkar S.R. , Balasubramanian K. , Bhave Tejashree M.
Published: October 2013

The idea of generating electricity from plastics itself sounds enthralling, but it is equally challenging to achieve in the lab and then take it to the production level. Polymer Solar Cells (PSCs) have the advantage of lower cost and flexibility but they do suffer from problems like low efficiency and smaller service life which is mainly due to limited absorption spectra, poor charge mobility and the degradation of the polymers. A combination of narrow band donor and fullerene derivative is one of the possible approaches to fabricate a working device. In this work, various experimental techniques have been optimised in order to achieve better efficiency of the PSCs in atmospheric condition. Optimized parameters from polymer mixing ratio, spin coating, annealing and others were used to enhance efficiency of device. Parameters were optimized with the help various techniques viz. Viscometer, Thermo Gravity Analysis, UV-vis spectroscopy, Scanning Electron Microscopy and I-V measurement system. We report 0.76% efficiency in these solar cells, which were fabricated in open atmospheric condition. The as-prepared device showed a good performance with an open-circuit voltage (Voc) 0.74 V, short circuit current (Isc) 0.6 mA, a fill factor (FF) of 35%.
Improved Open Circuit Voltage in Nano-Porous Silicon Based Hydrogen Fuel Cell
Authors: Agarwal Himanshu , Bhave Tejashree M.
Published: October 2013

Hydrogen fuel cell generates electrical energy from the electrochemical reaction of hydrogen and oxygen with water vapor as a by-product. Polymer Exchange Membrane Fuel Cell (PEMFC) and Direct Methanol Fuel Cell (DMFC) which are normally utilized for portable applications are not only costly due to platinum electrodes, polymer membrane and supply of hydrogen or methanol as a fuel but also not integrable with silicon fabrication technology. Novel fuel cell based on nanoporous silicon (PS) as Metal/nanoPS/silicon Schottky type structure is under development and Open Circuit Voltage (Voc) upto 550 mV with Au as anode catalyst has been reported. Such fuel cell uses nanoporous silicon layer as proton exchange membrane. This type of structure is found to show humidity-voltaic effect i.e. generation of voltage in humid ambient. Humidity-stimulated voltage generation is facilitated by the hydrogen component of water present in the atmosphere. In the present work, our main objective was to improve Voc. We achieved Voc upto 1.118 V by restricting the pore size of nanoporous silicon to 4-5 nm and thickness of the Cu film to 100 nm. These results suggest that this type of fuel cell could be utilized to develop self-powered integrated circuit.
Efficiency-Limiting Recombination in Multicrystalline Silicon Solar Cells
Authors: Schubert Martin C. , Schön Jonas , Abdollahinia Alireza , Michl Bernhard , Kwapil Wolfram , Schindler Florian , Heinz Friedemann , Padilla Milan , Giesecke Johannes A. , Breitwieser Matthias , Riepe Stephan , Warta Wilhelm
Published: October 2013

This work presents recent advances in the characterisation of carrier recombination and impurities at Fraunhofer ISE. The role of iron contamination during crystallisation is analysed in more detail. Numerical simulations and comparisons to experimental data are presented which demonstrate the impact of iron from the crucible and crucible coating and show the in-diffusion of iron into the silicon melt as well as into the solid silicon during crystal cooling. Measurements of spatially resolved carrier lifetime and interstitial iron concentration on wafers after phosphorus diffusion gettering are used as input for cell efficiency modelling which reveals the specific and quantitative role of iron on cell parameters in multicrystalline silicon. A new photoluminescence based method is presented which quantitatively determines the interstitial iron concentration in finished solar cells. We finally present advances in defect characterisation with sub-micrometre resolution: We show recent progress in micro photoluminescence spectroscopy for the quantitative measurement of interstitial chromium with high spatial resolution. A further development of this setup will be discussed: By combining the principle of Light Beam Induced Current (LBIC) or voltage (LBIV) and the highly localized illumination, images of carrier recombination at local defects are presented which feature a, compared to EBIC, higher signal-to-noise ratio.
Photoluminescence Imaging of Silicon Bricks
Authors: Mitchell Bernhard , Weber Juergen W. , Juhl Mattias , Macdonald Daniel , Trupke Thorsten
Published: October 2013

Photoluminescence imaging techniques have recently been extended to silicon bricks for early production quality control and electronic characterisation in photovoltaics and microelectronics. This contribution reviews the state of the art of this new method which is fundamentally based on spectral luminescence analyses. We present highly resolved bulk lifetime images that can be rapidly extracted from the side faces of directionally solidified or Czochralski grown silicon bricks. It is discussed how detailed physical modelling and experimental verification give good confidence of the best practice measurement errors. It is also demonstrated that bulk lifetime imaging can further be used for doping and interstitial iron concentration imaging. Additionally, we show that full spectrum measurements allow verification of the luminescence modelling and are, when fitted to the theory, another accurate method of extracting the absolute bulk lifetime.
Inline PL Inspection and Advanced Offline Evaluation of Passivation Defects, Charge and Interfaces
Authors: Findlay Andrew , Lagowski Jacek , Wilson Marshall , D'Amico John , Savtchouk Alexandre , Korsos Ferenc , Nadudvari György
Published: October 2013

Recently introduced techniques for whole wafer mapping and imaging create new possibilities for root cause analysis of emitter passivation defects. Inline compatible PL imaging identifies such defects as localized regions with increased emitter saturation current and reduced implied open circuit voltage. Advanced offline evaluation of defective areas can be then performed with multiparameter noncontact measurements capable to establish the role of surface recombination, the interface trap density, or the dielectric charge that controls the field-effect passivation. The relevant novel metrologies are discussed and are illustrated using examples of advanced silicon passivation by dielectric films and by a-Si heterojunction structures.
Transition Metal Precipitates in Mc Si: A New Detection Method Using 3D-FIB
Authors: Zuschlag Annika , Schwab Michail , Merhof Dorit , Hahn Giso
Published: October 2013

To investigate transition metal precipitates in Si, synchrotron based measurements, like micro x-ray fluorescence (μXRF) or detailed transmission electron microscopy (TEM) studies, are usually necessary. Transition metals are among the most detrimental defects in multi-crystalline (mc) silicon material for solar cell applications, due to their impact on minority charge carrier lifetime and possible shunt formation. We present another possibility to investigate transition metal precipitates by 3-dimensional focused ion beam (3D-FIB) cutting using a combined scanning electron microscope (SEM) SEM-FIB-system. This method is able to detect transition metal precipitates down to 5 nm in radius and provides additional information about the 3D shape, size and spatial distribution of the precipitates.
Iron Management in Multicrystalline Silicon through Predictive Simulation: Point Defects, Precipitates, and Structural Defect Interactions
Authors: Hofstetter Jasmin , Fenning David P. , Powell Douglas M. , Morishige Ashley E. , Buonassisi Tonio
Published: October 2013

In multicrystalline silicon for photovoltaic applications, high concentrations of iron are usually found, which deteriorate material performance. Due to the limited solubility of iron in silicon, only a small fraction of the total iron concentration is present as interstitial solute atoms while the vast majority is present as iron silicide precipates. The concentration of iron interstitials can be effectively reduced during phosphorus diffusion gettering (PDG), but this strongly depends on the size and density of iron precipitates, which partly dissolve during high-temperature processing. The distribution of precipitated iron varies along the height of a mc-Si ingot and is not significantly reduced during standard PDG steps. However, the removal of both iron interstitials and precipitates can be enhanced by controlling their kinetics through carefully engineered time-temperature profiles, guided by simulations.
Fast and Slow Vacancies in Silicon
Authors: Voronkov Vladimir V. , Falster Robert
Published: October 2013

Vacancies (and probably also self-interstitials) in silicon appear to exist in several forms (atomic configurations) some of them being fast diffusers and other slow diffusers. The data on enhanced self-diffusivity under proton irradiation, on vacancy and oxide precipitate profiles installed by Rapid Thermal Annealing, and on the self-diffusivity under equilibrium conditions suggest that there are at least two kinds of vacancy: 1) Vw - a fast-diffusing localized vacancy manifested in electron irradiated samples (Watkins vacancy), 2) Vs - a slow-diffusing extended vacancy manifested under hot proton irradiation. In RTA experiments, these two species behave as one equilibrated subsystem of a moderate effective diffusivity intermediate between those of Vw and Vs. There is also strong evidence in favor of a third kind of vacancy: Vf a fast extended species, which controls the grown-in voids in silicon crystals.
Calibration of IR Absorbance in Highly Nitrogen Doped Silicon
Authors: Lauer Kevin , Möller Christian , Porytskyy Rudolf , Strutzberg Hartmuth , Schulze Dirk , Schley Michael , Schaaff Friedrich
Published: October 2013

Infrared absorption spectra of highly nitrogen doped multicrystalline float zone silicon are reported. By measuring the nitrogen content in silicon using SIMS, a calibration function of the IR absorption coefficient at 963 cm-1 (T = 300 K) and the nitrogen concentration is deduced: cN = (1.29 ± 0.05)×1017cm2α963. The calibration factor is 30 % less than the calibration factor reported by Y. Itoh et al. [Appl. Phys. Lett. 47 (1985) 488].
Influence of Cu Concentration on the Getter Efficiency of Dislocations and Oxygen Precipitates in Silicon Wafers
Authors: Kot Dawid , Kissinger Gudrun , Schubert Markus Andreas , Sattler Andreas , Müller Timo
Published: October 2013

Two getter tests were carried out in order to study the getter efficiency of oxygen precipitates in silicon samples contaminated with low and high Cu concentration. The samples were pre-treated by RTA followed by annealing in the temperature range between 700 °C and 1000 °C for various times in order to establish different concentrations and different sizes of oxygen precipitates in the samples. From the analysis of the results of the normalized inner surface and the gettering efficiency, it was deduced that in highly contaminated samples Cu precipitates more easily at dislocations than at the surface of oxygen precipitates. Contrarily, in the samples contaminated with low Cu concentration the presence of dislocations does not improve the getter efficiency. Cu precipitates were found at the edge of a plate-like precipitate in a sample with low Cu concentration.
High n-Type Doping in Ge for Optical Gain and Lasing
Authors: Cai Yan , Michel Jurgen
Published: October 2013

We review two ex-situ doping methods to achieve high n-type doping up to mid-1019 cm-3 in Ge-on-Si thin films. For both, delta doping and ion implantation, rapid thermal annealing is used to diffuse phosphorus from a diffusion source into the single crystal Ge layer. The diffusion mechanism is studied and we find that dopant enhanced diffusion in in-situ doped Ge attributes to the high doping level. A band gap narrowing effect is observed in highly doped n-type Ge through photoluminescence measurements by determining the photoluminescence peak shift. An empirical linear expression of the direct band gap narrowing shift with carrier concentration is proposed.
Electronic States and Optical Gap of Phosphorus-Doped Silicon Nanocrystals Embedded in a Silica Host Matrix
Authors: Konakov Anton A. , Belyakov Vladimir A. , Burdov Vladimir A.
Published: October 2013

Using the envelope-function approximation the electronic states and the optical gap of silicon nanocrystals heavily doped with phosphorus have been calculated. Assuming the uniform impurity distribution over the crystallite volume we have found the fine structure of the electron ground state (induced by the valley-orbit interaction) and the optical gap as a function of the crystallite size and donor concentration. It is shown that the energy of the ground singlet state decreases almost linearly as the concentration increases, while the valley-orbit splitting increases nonlinearly. Phosphorus doping also results in the decrease of the nanocrystal gap with increasing the impurity concentration.
Photoluminescence and Raman Scattering Behavior of Si Rich Silicon Oxynitride Films Annealed at Different Temperatures
Authors: Naseka Victor , Nasieka Iurii , Voitovych Maria , SARIKOV Andrey , Lisovskyy Igor , Strelchuk Victor
Published: October 2013

In this work, we study the photoluminescence and the Raman scattering behavior of Si rich silicon oxynitride films obtained by plasma enhanced chemical vapor deposition as a result of thermal anneals during 1 hour in the temperature range from 400O to 1100OC and discuss the ways of the transformation of structure in them.
Defect Generation and Propagation in Mc-Si Ingots: Influence on the Performance of Solar Cells
Authors: Sopori Bhushan , Mehta Vishal , Devayajanam Srinivas , Seacrist Mike , Shi Gang , Chen J , Deshpande Aditya , Binns Jeff , Appel Jesse
Published: October 2013

This paper describes results of our study aimed at understanding mechanism (s) of dislocation generation and propagation in multi-crystalline silicon (mc-Si) ingots, and evaluating their influence on the solar cell performance. This work was done in two parts: (i) Measurement of dislocation distributions along various bricks, selected from strategic locations within several ingots; and (ii) Theoretical modeling of the cell performance corresponding to the measured dislocation distributions. Solar cells were fabricated on wafers of known dislocation distribution, and the results were compared with the theory. These results show that cell performance can be accurately predicted from the dislocation distribution, and the changes in the dislocation distribution are the primary cause for variations in the cell-to-cell performance. The dislocation generation and propagation mechanisms, suggested by our results, are described in this paper.
Analysis of Inhomogeneous Dislocation Distribution in Multicrystalline Si
Authors: Chen Jun , Prakash Ronit R. , Li Jian Yong , Jiptner Karolin , Miyamura Yoshiji , Harada Hirofumi , Ogura Atsushi , Sekiguchi Takashi
Published: October 2013

Grain boundaries and dislocations are major crystallographic defects in multicrystalline Si materials for solar cells. Heavily dislocated grains are detrimental to the photovoltaic performance. This paper attempts to clarify the origin of inhomogeneous defect distribution in multicrystalline Si. The impacts of crystal orientation and grain boundary were investigated. The crystal orientation gives an important geometrical effect in the possibility of initiating slip in a grain when subjected to stress. The presence of grain boundary can also affect dislocation distribution depending on boundary character.