bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave-Assisted Synthesis and Photocatalytic Activity of Thiourea-Modified ZnO Nanoparticles
Authors: Zhang Hai Feng , Lu Shi Xiang , Xu Wen Guo , Gao Feng Xin
Published: October 2013

Thiourea-modified ZnO nanoparticles were prepared by the microwave-assisted method. The nanoparticles were characterized by X-ray diffraction (XRD), High-resolution transmission electron microscope (TEM), UV-Vis absorption spectroscopy (UV-Vis) and X-ray photoelectron spectroscopy (XPS). ZnO nanoparticles presented typical wurtzite structure. Microwave-assisted method and thiourea modifying reduced the particle size of ZnO corporately and the particle size of 2.0 mol% thiourea/ZnO was about 3 nm. The photocatalytic efficiency of thiourea-modified ZnO was influenced by the molar precent between thiourea and ZnO and 2.0 mol% thiourea/ZnO had the highest photocatalytic activity. The degradation rate of 30 mg/L C.I. Reactive Blue 4 could get to 85% in 50 min at room temperature when the concentration of 2.0 mol% thiourea/ZnO was 0.10 g/L.
Solid-Phase Synthesis of DNA Chemical Sensor
Authors: Zhang Hui Yong
Published: October 2013

Oligonucleotides are essential components of many applications in molecular biology. The synthesis chemistry is robust and commercial oligonucleotide synthesizers have taken advantage of the chemistry to provide oligonucleotides of high quality and purity. This paper established nucleic acid synthesis platform to carry out the synthesis of the labeled nucleic acid probes based on the DNA synthesizer and solid-phase synthesis technology. We chose to study the automated synthesis starting from DMT protected FAM labeled amidite attached to controlled pore glass (CPG) support and the standard trityl-off oligonucleotide synthesis cycle was performed, yielding the solid-supported oligonucleotide. The reported automated solid-phase oligonucleotide synthesis procedure successfully employs the common iterative synthesis, deblocking, activation, coupling, capping, oxidation, and isolation steps in standard oligonucleotide synthesis. The automated synthetic approach can also be applied to oligonucleotides of different length, composition of nucleotide, demonstrating the universality of the method. Moreover, the synthesis involved the use of commercially available, safe, stable, and inexpensive reagents, particularly advantageous and attractive for their use in automated solid-phase synthesis. The synthesis allows custom tailoring of their structure to the requirements of biological assays within hours, as opposed to traditional approaches that require weeks or months of work in the laboratory. Therefore it will become much easier to investigate biological interactions and optimize for objectives such as the receptor mediated targeting of oligonucleotides.
Research on Protecting the Silk Fabrics from Fungus Erosion with Isothiazolone Resin Film Barrier and Inhibitor
Authors: Li Shi Chao , Tang Chang Bo , Wang Ting Ting , Shi Jian Ping
Published: October 2013

Fungus corrodes silk and makes their products quickly corrosion and crisp. This article disclosed that the silk fabrics treated with finishing resins containing isothiazolone to form the closing film. On the one hand, the film can prevent fungus penetrating into silk fiber matrix. On the other hand, it can make use of the antimicrobial of isothiazolone to improve its function. So the protection method can change the single isolation action to produce double action way and prevent fungus penetrating into silk fiber matrix.
Performance Improvement of MFCs by Treatment of Carbon Cloth Anode with Ultrasonic or Spent Anolyte
Authors: Liu Wei Feng , Cheng Shao An
Published: October 2013

In order to improve the power generation of microbial fuel cells (MFCs), carbon cloth anode was treated with ultrasonic or spent anolyte in this work. The maximum power density of a single-chamber air-cathode MFC was improved from 611.5 mW/m2 to 754.3 mW/m2 and 811.7 mW/m2, and the reactor start-up time was shortened by 7.3% and 22.7% respectively after treatments of the anode with ultrasonic and spent anolyte. Polarization tests reveal that the treated anodes have a smaller electrode polarization at high current densities than the control. MFCs with the treated anodes exhibited lower internal resistances than the untreated anode, which may arise from the enhanced substrate oxidation activity and extra-cellular electron transfer efficiency on these anodes. Results from this study indicated that treatment of anode with ultrasonic or spent anolyte was a simple and effective approach for improving the performance of MFCs.
Flame Retardancy of Polypropelene/LDHs Composites: An Influence of Organo-LDH Types
Authors: He Ming , He Xue Jun , Wang Lin Jiang , Xie Xiang Li
Published: October 2013

Organic-LDHs was prepared by three methods including co-precipitation, ionexchange and roast reduction process using Lauryl alcohol phosphoric acid ester potassium (MAPK) asmodifier.Polypropylene (PP)/Organically-modified layered double hydroxides (LDH) was prepared by the melt blending method. The structures and morphologies of composites were characterized by X-ray diffraction and TEM. TGA, cone calorimeter, limiting oxygen index (LOI) and the UL94 protocol were used to characterize the thermal stability and fire properties of composites. The results indicate that MAPK was successfully intercalated into the interlayer of LDHs and MAPK has a different arrangement in the interlayer of organicLDHs for different preparation methods of LDHs. PP/ionexchangeorganicLDHs (PP/ion-o-LDHs) and PP/roast reductionorganicLDHs (PP/ro-o-LDHs) show a better dispersion of LDH in PP than PP/co-precipitationorganicLDHs (PP/co-o-LDHs) composites. Compared to pristine PP, the peak heat release rate of PP/10% co-o-LDHs, PP/10% ion-o-LDHs and PP/10% ro-o-LDHs decreased by 21%, 33% and 30% respectively. The limiting oxygen index increased by 3.7 from 17.2(in PP) to 20.9(in PP/10% ion-o-LDHs). All of the composites could obtain an HB in the UL-94 horizontal burning.
Study on the Performance of Ionic Polymer-Metal Composites of Various Fabrication Technique
Authors: Zhao Yang , Xu Bing , Xu Bu Lei , Yu Ling Ke , Sun Dao Heng
Published: October 2013

onic Polymer Metal Composites (IPMC) is a new kind of electro-active smart material that has many advantages including bending actuation, large displacement, low weight, low driven voltage, low power consumption, flexibility etc. The mechanical characteristic of IPMC is related to ionic polymer membrane, such as thickness, roughening, cation type and so on. In this paper, the actuation principle of IPMC and fabrication technique of NafionTM membrane is presented. The performance of IPMC with Nafion membrane pre-treatment, different cation type and thickness are investigated. Experiment results showed that the fabrication process of ionic polymer membrane Nafion change can improve the performance of IPMC effectively.
Photon Cascade Emission of Pr3+-Doped K2YZr(PO4)3 Phosphor
Authors: Liang Wei , Niu Liang Feng , Gao Yuan Hao , Wang Yu Hua
Published: October 2013

In present work, K2Y1-xZr (PO4)3:Prx3+(0.01x0.05) samples were prepared by solid-state reaction method and their photoluminescence properties were investigated in ultra-violet (UV) and vacuum ultra-violet (VUV) region. The photon cascade luminescence (PCL) of Pr3+had been observed. All the results indicate that, in this Pr3+-doped K2YZr (PO4)3phosphor, even if the1S0state is higher than the lowest 4f5d energy level, the photon cascade emission (PCE) process for Pr3+still could occur under 147 nm and 234 nm (4f15d1state) excitation. Therefore, K2YZr (PO4)3was an ideal host for Pr3+to implement the PCE process successfully.
Study on Impurities Removal from Silicon by Slag Refining with Fe (OH)3-SiO2-CaF2 Slag System
Authors: Lu Cheng Hao , Fang Ming , Lai Hui Xian , Huang Liu Qing , Chen Juan , Chen Yu Qing , Li Jin Tang , Ma Wen Hui , Sheng Zhi Lin , Luo Xue Tao
Published: October 2013

An innovating slag system, Fe (OH)3-SiO2-CaF2 system, was introduced in the metallurgical methods to purify silicon for photovoltaic application. The partition ratio of boron (LB) between slag and silicon was studied under different mass ratio of slag to silicon and varying mass ratio of Fe (OH)3 to SiO2 under argon condition at 1873K. The distribution of impurity elements in silicon after slag refining was detected by scanning electron scope and electron probe micro analysis. Experimental results illustrated that the Fe-Si binary system could promote the LB. Silicon was surrounded by amorphous slag. Impurity elements are concentrated in slag.
Synthesis and Characterization of Branched Poly(Ethylene Terephthalate)
Authors: Chen Yan Ming , Zhao Dan , Wang Li Yan , Wu Quan Cai
Published: October 2013

Linear and branched poly (ethylene terephthalate) were prepared by using terephthalic acid, ethylene glycol as main raw materials and pentaerythritol as polyfunctional monomer through melt polycondensation method. The samples were characterized with respect to intrinsic viscosity and differential scanning calorimeter (DSC). The results show that the low branched poly (ethylene terephthalate) could be obtained by the addition of tertrafunctional pentaerythritol through common melt polycondensation process.
Zinc Oxide Films and Nanowires Synthesized by Sol-Gel and Hydrothermal Methods and their Applications
Authors: Wei Wei , Zhang Chun Fu , Chen Da Zheng , Gao Rui , Wang Zhi Zhe
Published: October 2013

In this paper, we studied the methods to synthesize good ZnO materials that can be applied in real environment. First we used spin coating method to form a layer of sol-gel driven ZnO, and then a hydrothermal method was used to synthesize nanowires of ZnO on the already obtained ZnO films. Some methods of test, including AFM and SEM, were performed to analyze the different characteristics of the material. Finally, their applications in the fields of TFT and solar cell were studied. We find that the ZnO films and nanowires are good in quality and their applications in TFT and solar cell are satisfactory.
The Influences of Different Precursors on Morphology of Bi3TiNbO9 Powders Prepared by a Sol-Gel Method
Authors: Li Zuo Dong , Liu Dan
Published: October 2013

Bi3NbTiO9 (BNTO) powders were synthesized by a sol-gel chemical method using niobium oxalates, bismuth nitrate and tetra-n-butyl-titanate as starting materials. In order to determine the influence of the molar ratio of the deionized water to ethylene glycol on the particle morphology and crystallization, different molar ratios, the deionized water/ethylene glycol, were chosen to prepare BNTO powders. Single phase BNTO powders could be obtained at a calcinations temperature of 600°C. Moreover, the possible formation mechanism of BNTO powders was also proposed in this paper. In the baking process, perovskite phase BNTO was formed via a reaction between oxides and bismuth niobium.
Defect Depth of Thermal Non-Destructive Testing for the Titanium Implants
Authors: Zhu Qi Fang , Sun Ze Ming , Ma Tong Da , Li Pu , Fan Zhi Gang , Vavilov Vladimir Platonovič
Published: October 2013

In this paper, the results of the first-stage research devoted to infrared thermographic detection of cracks in titanium alloys are presented. In application to the inspection of bottom-hole defects in 9.6 mm-thick Ti6Al4V titanium alloy samples, it has been found that a minimum detected defect should have diameter from one to two times greater than its depth. Images of phase are more noise-resistant and able to reveal deeper defects compared to images of amplitude. The test results obtained show that the Fourier analysis is a convenient data processing technique in active thermal NDT.
Exploit of Shipping Auxiliary Swing Test Platform
Authors: Wang Jia , Lu Dao Hua , Xie Song Lian
Published: October 2013

Shipping auxiliary swing test Platform is a kind of test device which can complete performance tests of the ship auxiliary equipment by simulating the motion of ships in the laboratory environment. This article presented a swing test-bed with high torque dynamic load of three-degree of freedom (3-DOF), simulated mainly the motion of rolling, pitching and heaving in a specific sea state. Put forward some comparison and design of the structure schemes against the requirement of high torque load, choose the best scheme according to the test requirement, and introduce some key accessories design of the made reliability accounting on the key mechanical structure of the swing test-bed.
Influencing Factors of Coal Gangue Carbothermal Reduction and Nitridation Reaction
Authors: Duan Feng , Ma Ai Qiong , Xiao Guo Qing , Zhang Xiao Hui , Yu Ren Hong
Published: October 2013

nfluencing factors of target products such as X phase, β-SiAlON phase and O-SiAlON phase of Inner Mongolia coal gangue carbothermal reduction and nitridation were researched by calculating the loss rate on ignition of specimens, and by means of XRD and SEM. During the carbothermal reduction and nitridation reaction of coal gangue, the loss rate on ignition of specimens rises with carbon reducer increasing, and keeping time has a little influence on the loss rate on ignition of specimens. If β-SiAlON is target phase, the yield from corundum is much higher than that from special grade bauxite. Corundum or bauxite is used as starting material, the yield of X phase is low and the highest yield is only 12.88%. For the carbothermal reduction and nitridation reaction of coal gangue, the appropriate addition of reducer carbon is 10%-16%, and temperature influence is larger. The reaction temperature over 1420°C and keeping time of 6h are beneficial to the formation of X phase, β-SiAlON and O-SiAlON.
Differences of Bioleaching of Pyrites from Different Geo-Genetic Deposits by Leptospirillum ferriphilum
Authors: Zhang Xun , Gu Guo Hua , Hu Ke Ting , Qiu Guan Zhou
Published: October 2013

In this paper, the bioleaching behavior of three pyrites from different geological origins (high-temperature hydrothermal, low-temperature hydrothermal and coal sedimentary) by L. ferriphilum was studied. The internal structure of three pyrite samples were investigated using optical microscope. The results show that the physical characteristics and internal structures of pyrites from different geological origins are different, and this causes the divergences of their bioleaching behavior. High-temperature hydrothermal pyrite (n-type semiconductor tested) is not almost dissolved and the leaching rate is only 0.58%, while the leaching rate of low-temperature hydrothermal pyrite and coal sedimentary pyrite (both of p-type semiconductor tested) are 15.25% and 27.50% respectively. The Leica optical microscope test of p-type semiconductor pyrites indicates that coarse particle of low-temperature hydrothermal pyrite is crystallized well and sedimentary pyrite consists of fine-grained crystal with poor crystallinity. This was suggested to cause the divergences of the bioleaching rate of both p-type semiconductor pyrites. In view of mineralogy, the semiconductive type of pyrite is the primary factor affecting its bioleaching. Furthermore, the different internal structure of pyrites will further have an influence on bioleaching for the same semiconductive type.Key words: pyrite; bioleaching; L. ferriphilum; geo-genetic
Isolation and Characterization of Actinomycetes from Acidic Cultures of Ores and Concentrates
Authors: Matsubara Akemi , Hurtado Jasmin E.
Published: October 2013

Mining industry is a source of wealth but also of environmental pollution in Peru. In this study 12 colonies of actinomycetes were isolated in acidic cultures from mineral ores and concentrates from mines of the Peruvian highlands. The isolates were characterized phenotypically by microscopy and growth at different conditions as pH tolerance, temperature, and sodium chloride, heavy metals resistance; ferrous iron and thiosulfate oxidation. All isolates were identified as actinomycetes based on their cultural and spore characteristics. Most of the isolates were able to grow at 8 - 45°C and pH 4 - 11. 60% of isolates grew at 10% NaCl but none of them growth at 13%. Iron oxidation was shown by 60% of isolates at pH 4, but only 25% were able to oxidize iron at pH 2. Thiosulfate oxidation was not detected in any isolate. Most of the isolates showed capacity to grow in medium with 200 ppm of Pb, Fe, Zn and 100 ppm of Cu. All of the physiological characteristics found in this work indicate the potential of these isolates as source for bioremediation and bioleaching.
Recovery of Zinc during the Pre-Treatment of a Refractory Gold-Bearing Ore
Authors: Marchevsky Natalia , Urbieta María Sofía , Bernardelli Cecilia , Mas Miguel , Donati Edgardo
Published: October 2013

Mesophilic bacteria were enriched from samples collected from acid mine drainages in La Carolina (San Luis, Argentina). Two enrichments, E1 and E2, showed suitable rates for iron or sulphur oxidation, respectively. Both enrichments were characterized by FISH analysis. They were mainly composed by Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans respectively. Studies with both, mixed and individual enrichments, showed biooxidation (measured as iron solubilisation) of a refractory gold-bearing pyrite ore from Hualilán (San Juan, Argentina). Pyrite and sphalerite were the main mineral species in the ore with 7% w/w and 8% w/w of iron and zinc and approximately 25 ppm of gold. Leaching experiments (2% w/v ore, 1.8 initial pH, 180 rpm and 30°C) were carried out with the addition of different alternative energy sources (6.67 g/L sulphur powder, 1 g/L ferrous iron, 0.02% w/v yeast extract). Redox potential, pH, ferrous iron concentration and total Fe and Zn were measured regularly. A 100% of iron leaching (after 28 days in the best experimental condition) was observed in some of the cultures. In other systems high zinc release was obtained (100% of dissolution after 28 days in the best experimental condition). Our results strongly suggest that under the correct operating conditions, biooxidation pre-treatment can be used to recover zinc as a subproduct of gold extraction from refractory ore.
Acid Drainage and Metal Bioleaching by Redox Potencial Changes in Heavy Polluted Fluvial Sediments
Authors: Porzionato Natalia , Mellota Mariangeles , Candal Roberto , Curutchet Gustavo
Published: October 2013

Sediments from polluted urban streams act as a sink of contaminants. The high content of organic matter and sulphides makes the system appropriate for binding heavy metals. However, changes in the redox potential leads to processes in which sediments acts like a low sulphidic ore in an oxidizing environment, and could generate acid drainages. Human and not human disturbances of the sediments could derive in its oxidation catalyzed by sulphur oxidizing bacteria (SOB). This process leads to acidification and metal release. In this study we analyze the acidification potential of anaerobic sediments of polluted streams near Buenos Aires with static and kinetic methods. The results remark the necessity to consider this process before any sediment management action.
Bioleaching for Extraction of Metals and Detoxification of Activated Sludges
Authors: Groudev Stoyan Nikolov , Nicolova Marina V. , Spasova Irena , Georgiev Plamen S.
Published: October 2013

Samples of anaerobically digested sludges from municipal wastewater treatment installations containing several toxic heavy metals (Cu, Zn, Ni, Co, Cr, Mn, Fe), different organochemicals and biological pollutants (mainly bacteria of the genera Escherichia, Klebsiella, Streptococcus and Clostridium) were subjected to different procedures for detoxification to make possible their use in agriculture. It was found that the bioleaching of these sludges at 70 °C by mixed cultures of extremely thermophilic chemolithotrophic bacteria was the most efficient way to decrease below the relevant permissible levels all above-mentioned pollutants. The bioleaching was carried out in reactors with mechanical stirring and enhanced aeration (by CO2 enriched air) under batch and continuous-flow conditions. The extraction of some metals (mainly of Cu and Zn) which were present in relatively high concentrations in some sludge samples was very efficient and exceeded 90 % within residence times of about 96 - 120 hours. The dissolved copper and zinc were recovered from the pregnant solutions after bioleaching by means of solvent extraction plus electrolysis. At the same time, the bioassimilable forms of N, P, K and the essential microelements were still present in sufficient concentrations in the pretreated sludges making them suitable for use in agriculture. This was confirmed by experiments in green-houses with plants intended for use in the bioremediation of post-mining landscapes.
Staphylococcus equorum Isolated from Seabed as Potential Biotool to Cr(VI) Remediation
Authors: Pradel Paulina , Hernández Carolina , Tello Mario , Villarroel Maria Paz , Corsini Gino , González Alex
Published: October 2013

Normal 0 21 false false false ES-CL X-NONE X-NONE MicrosoftInternetExplorer4 Cr(VI)is frequently used in several industrial activities, due to its uncontrolled spill this contaminant has generated serious damage to the environment: chromium hexavalent has a high oxidation potential and is able to go through biological membranes. As consequence Cr(VI)is described as a persistent contaminant with a high toxicity. It has been searched for alternative methods to remediate or detoxify environments contaminated with Cr(VI). The use of microorganisms able to absorb or reduce this type of contaminant is discerned as a potential biotool for remediation of metals-enriched industrial wastes. In order to isolate and identify environmental microorganisms with this capacity, we isolated a bacterium named LMA-2 with a selective pressure of 60 mM of Cr(VI) from contaminatedmarine sediment. In the morphologic analysis, this marine microorganism evidenced that corresponds to a Gram-positive cocci. This resistant bacterium has a minimal inhibitory concentration for Cr(VI) of 750 mM. The characterization and identification of this strain was made through 16S ribosomal RNA gene, this result revealed that it corresponds to Staphylococcus equorum. Assays using atomic absorption spectrophotometer (AAS) shows that this strain is able to ireduce the concentration of soluble Cr(VI) The capacity of this strain to remediate Cr(VI) was determined in 142.8 mg/L at 10 h of exposition. Our results showed the high resistance and the ability for Cr(VI) remediation by Staphylococcus equorum. These results suggest that this marine bacterium could be a prospect for future use as a biofilter for seabed marine environment decontamination. st1\:*{behavior:url(#ieooui) } /* 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-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}
Development of Alamine-336-Impregnated Alginate Capsule for Selective Recovery of Gold from Multi-Metal Solution
Authors: Wei Wei , Won Sung Wook , Yun Yeoung Sang
Published: October 2013

In this study, we developed Alamine-336-impregnated alginate capsule (Alamine-336-AC) by using a simple method. Alamine-336 was used as a model solvent extractant because it has good selectivity toward gold. Alamine-336-AC was prepared at different ratios of A (mixture of 1% CaCl2 and 2.5% carboxymethyl cellulose) and B (Alamine-336) solutions. A comparative study revealed that the ratio of 9:1 (A:B) was the best condition for fabricating Alamine-336-AC. Microscope images revealed that Alamine-336 was well dispersed in the Alamine-336-AC. The maximum of gold uptake by Alamine-336-AC was 284.1 mg/g, which was about 5 times higher than those of Pt and Pd. Kinetics of adsorption was also investigated.
Development of Powerful Bacterial Biosorbent Fibers for Recovery of Ruthenium and Comprehension of the Role of Bacterial Biomass in the Fiber
Authors: Won Sung Wook , Kwak In Seob , Yun Yeoung Sang
Published: October 2013

The main purpose of this work is to develop and evaluate the fibrous bacterial biosorbents and to undestand the role of bacterial biomass in functionalizing polyethylenimine (PEI)-coated bacterial biosorbent fiber (PBBF). For this, chitosan fiber (CSF) and chitosan/biomass composite fiber (CSBF) were separately prepared by extruding chitosan solution and chitosan/biomass suspension, respectively. To make PBBF, the CSBF was coated with PEI and then cross-linked by glutaraldehyde. An acetic acid waste solution containing the initial ruthenium concentration of 1822.9 mg/L was used as a model waste solution. Batch sorption studies showed that the maximum Ru uptake of PBBF was 110.5 mg/g, which was 16.5 times higher than that of the commercial ion exchange resin, Lewatit MonoPlus M600. In addition, the thin fiber type of biosorbent showed as fast sorption kinetics as powder form of the raw biomass. Therefore, PBBF was evaluated as a promising biosorbent for recovery of Ru from Ru-containing acetic acid waste solutions. The role of biomass in the fiber was also investigated through sorption experiments and SEM, FTIR and XPS analyses with differently prepared fiber sorbents. In the case that the CSF was made without the biomass, it could not be coated with PEI. Meanwhile, the CSBF could successfully coat with PEI and primary amine groups were significantly increased on the surface of the fiber. Therefore, it can be concluded that the biomass should be essential to make PEI-reinforced chitosan fiber and that the negatively charged carboxyl groups on the biomass give the driving force for binding of cationic polymer PEI.
Recovery of Zero-Valent Ruthenium from Acetic Acid Waste Solution by a Combined Process of Biosorption with Bacterial Biosorbent Fibers and Incineration
Authors: Kwak In Seob , Won Sung Wook , Shin Jang Sik , Yun Yeoung Sang
Published: October 2013

This study introduces a new process for the recovery of zero-valent ruthenium (Ru) from acetic acid waste solution by a combined process of biosorption with bacterial biosorbent fibers and incineration. As an effective sorbent to bind Ru-acetate complexes, polyethylenimine (PEI)-modified bacterial biosorbent fibers (PBBF) were developed and used for the experiments. The PBBF were prepared by extruding the blended mixture of chitosan-Corynebacterium glutamicum biomass as a fiber, coating the fiber with PEI and cross-linked using glutaraldehyde, consecutively. The role of chitosan in the bacterial biosorbent fiber was binder of the biomass. Batch biosorption studies showed that the maximum Ru uptakes of raw biomass and PBBF were estimated to be 16.0 and 110.5 mg/g, respectively. Kinetic studies showed that PBBF was as fast as powder form of raw biomass. After biosorption, the Ru-acetate complexes ions sorbed biosorbents were incinerated for recover Ru as a metallic form. These biosorbent constituents could be burnt out and at the same time, the sorbed Ru-acetate complexes ions could be reduced to Ru0. X-ray photoelectron spectroscopy (XPS) results indicated that the Ru-acetate complexes ions were able to be reduced into metallic form of zero-valent Ru. X-ray fluorescence spectrometry (XRF) was applied for analysis of impurity metals in the recovered Ru containing ashes. The purity of metallic Ru by means of XRF was 99.79%. The proposed sequential process of biosorption and incineration for recovery of Ru from acetic acid waste solution would contribute to the solution of several problems such as the Ru recovery efficiency, generation of secondary waste, and recover costs and energy.
Anaerobic Growth of Acidithiobacillus ferrooxidans on Pyrite
Authors: Escobar Blanca , Vargas Tomas
Published: October 2013

In the bioleaching of mineral sulphides under the catalytic action ofAt. ferrooxidans,ferrous ion oxidation and sulfides/sulfur solubilization uses oxygen as the final electron acceptor. Also, under anaerobic conditions,At. ferrooxidanscan alternatively catalize the oxidation of sulfur or reduced inorganic sulfur compounds (RISC) using ferric iron as electron acceptor [1]. The formation of Fe (II) from pyrite and covellite in the ferric anaerobic bioleaching withA. ferrooxidans,has been studied and well documented [2,3]. The requirements of ferric iron as electron acceptor for the anaerobic growth ofAt. ferrooxidanson elemental sulfur has been demonstrated and a linear relationship was obtained between the concentration of ferrous iron accumulated in the cultures and the increase in cell density [4]. It has been suggested a possible role in the solubilization of metals from sulfide ores involving the participation of the enzyme sulfur (sulfide): Fe (III) oxidoreductase [5]. Bacterial growth ofAt. ferrooxidanshas also been reported in the oxidative anaerobic respiration using hydrogen as electron donor and ferric iron as electron acceptor [6]. Anaerobic reduction of ferric iron and ferrous iron production from pyrite byAt. ferrooxidanshas been demonstrated [2], however there are no reports about bacterial growth using this mineral. In this work, we studied the anaerobic bioleaching of pyrite with the aim to determine ifAt. ferrooxidansis capable to anaerobic growth on pyrite using ferric iron as electron acceptor.
Tool Life and Wear Mechanism of Coated Si3N4 Ceramic Tools in Turning Grey Cast Iron
Authors: Kuzin Valery V. , Grigoriev Sergey N.
Published: October 2013

This paper presents results of the investigation of Si3N4 ceramic inserts with CVD coatings in turning grey cast iron. The high effectiveness of Si3N4 ceramic inserts with multi-layered coating in the finish turning of the grey irons was shown. It was established that at the heart of the wear mechanism of coated Si3N4 ceramic inserts there is a chain of relations cutting conditions loading fracture of coating сhipping of ceramic surface layer failure of tools. One of the important features of wear mechanism of these tools is the operational defects formed at the coating substrate interface.
Generation of Microelectrodes for Micro EDM
Authors: Miura Kohichi , Kohmo Shun Ichiro , Yamada Takazo , Lee Hwa Soo
Published: October 2013

In order to fabricate micro holes by EDM process, microelectrodes with high accuracy of form are needed. At present, micro electrodes are generated by grinding and/or on-machine EDM operations and then it is well known that efficient productivity of micro electrodes cannot be realized. Controlling method of thrust force for micro shaft is already proposed. Applying this method, thrust force is controlled to be 0 in turning operation, therefore microelectrodes are generated efficiently. Actually, microelectrode which diameter is less than 0.1 mm can be easily machined in short time. high-precision micro hole machining requires microelectrodes with high cylindricity. In this study, turning method for microelectrodes with high cylindricity is discussed.
Machining and its Influence to Surface Quality of Machine Parts
Authors: Holesovsky Frantisek , Novák Martin , Lattner Michal , Vyslouzil Tomas
Published: October 2013

A number of machine parts are provided with design notches for the mounting of lock ring, position of bearing, and cross over sub of diameters etc. These elements significantly affect the durability of machines parts and their influence is inherently implemented into their design. The question is machining itself, particularly ambient surface finishing and intrinsic notch element. The changes and behaviour of machined surface form also very interesting part of paper and particularly under load. A number of new findings concerning the influence of machining on durability of machine parts both under dynamic load and the cyclic tensile, bending at rotation and torque were discovered in this research. The findings are important for further development, mainly related to car and aviation industries.
Surface Roughness Modeling and Prediction by ANN when Drilling Udimet 720
Authors: Vrabel' Marek , Maňková Ildikó , Beňo Jozef
Published: October 2013

Article deals with design of artificial neural network (ANN) for prediction of the surface roughness as one of the important indicators of machined surface quality. Back propagation neural network was trained and tested for prediction of the machined surface roughness. Cutting conditions, selected monitoring indices and tool wear parameter were given as inputs to the ANN. Test sample was nickel based super alloy Udimet 720, which is used as material for highly stressed jet engine components. Experimental data collected from tests were used as input into ANN to identify the sensitivity among cutting conditions, monitoring indices and progressive tool wear and machined surface roughness.
Dependence of Shape Deviations and Surface Roughness in the Hardened Steel Turning
Authors: Struzikiewicz Grzegorz , Otko Tadeusz
Published: October 2013

The article focuses on analysis of the effects cutting parameters on the surface roughness and shape errors. Research was performed for longitudinal turning of hardened steel 145Cr with using ceramic tools of different nose radius. Shape deviations and roughness for machined surfaces ware determined. Results were analysed and conclusions were presented.
Advanced CNC Programming Methods for Multi-Axis Precision Machining
Authors: Grigoriev Sergey N. , Kutin Andrey A. , Turkin Mikhail
Published: October 2013

This paper presents a method to simultaneously increase the accuracy and decrease the calculation time for complex tool path programming in multi-axis machining centers. Examples of complex parts requiring such complex tool paths include various kinds of turbine blades, pump-forcing augers, teeth surfaces, etc. It explains the creation of topological structures on the basis of analytical spline curves with floating range definitions. The method for tool path calculation accommodates the specific requirements for multi-axis milling. The algorithms developed are the foundation for the CAD/CAM software that allows for NC programming and machining on 5-axis centers employing any design model. Industrial tests reveal a 70-80% reduction of NC programming time of parts with complex surfaces, reduced machining time of approximately 40-50% using basic high-speed cutting methods and custom-made tools. The advanced methods of NC programming result in substantially increasing machining accuracy.
Achievement of Precision Accuracy of Openings in Gas Turbine Engines Details
Authors: Kulikov M.Y. , Rygin Roman E. , Nechaev D.A.
Published: October 2013

In the present article are shown, dependences of a morphogenesis at a honing of chrome nickel alloys, on the basis of the analysis of physical processes of a honing of a hardly processed material. On the basis of the analysis of these made experiments, the reasons of insufficient firmness of the tool are given. Are provided, complex methods of achievement of demanded high precision of received openings, in the details executed from chrome nickel alloys.
A Comparison of EBIC, LBIC and XBIC Methods as Tools for Multicrystalline Si Characterization
Authors: Orlov Valeri I. , Feklisova Olga V. , Yakimov Eugene B.
Published: October 2013

A comparative study of multicrystalline Si based solar cells and plastically deformed single crystalline Si by the EBIC, LBIC and XBIC methods as well as a computer simulation were carried out. The XBIC measurements were realized on a laboratory X-ray source. Simulations of LBIC and XBIC contrast values for grain boundaries, dislocations and spherical precipitates were carried out for different diffusion length and beam diameter values. It is shown by a computer simulation that the LBIC and XBIC contrast of two-dimensional defects in the crystals with a large enough diffusion length can be a few times higher than that in the EBIC mode, i.e. these methods in recent multicrystalline Si structures allow to reveal grain boundaries with the lower recombination strength. The contrast of dislocations perpendicular to the surface can be comparable in all three methods. The XBIC and LBIC contrast of precipitates usually is essentially smaller than that in the EBIC mode and could approach it in the structures with the small diffusion length only. Experimental data confirming the results of simulations are presented.
Formation of Single and Double Donor States of Trivacancy-Oxygen Complexes in P-Type Silicon
Authors: Ganagona Naveengoud , Vines Lasse , Monakhov Edouard V. , Svensson Bengt Gunnar
Published: October 2013

Deep level transient spectroscopy (DLTS) has been applied to study the formation of trivacancy-oxygen complexes in Si. Samples of p-type Czochralski grown (Cz) silicon, with a boron doping concentration of ~1x1015 cm-3, have been irradiated at room temperature (RT) with 1.8 MeV protons to a dose of 5×1012 cm-2. Two new energy levels at Ev+0.24 eV and Ev+0.11 eV (Ev denotes the valence band edge) emerge when the divacancy (V2) to divacancy-oxygen (V2O) transition takes place during post-irradiation annealing. The concentration is ~30% relative to V2 (or V2O) and further, the two new levels exhibit an almost one-to-one correlation in strength. The present results strongly support that both levels are related to the same defect with a possible identification as single and double donor states of V3O.
Dislocation Motions in Czochralski Silicon Wafers Treated by Rapid Thermal Processing under Different Atmospheres
Authors: Xu Ling Mao , Gao Chao , Ma Xiang Yang , Yang De Ren
Published: October 2013

Effects of prior rapid thermal processing (RTP) under different atmospheres on the motion of dislocations initiated from indentations in Czochralski (CZ) silicon have been investigated. It is found that the maximum gliding distances of dislocations in the specimens with the prior RTP under nitrogen (N2) atmosphere are much smaller than those in the specimens with the prior RTP under argon (Ar) atmosphere. This is also the case when the specimens received annealing for oxygen precipitation (OP) subsequent to the RTP at 1250 °C under N2 and Ar atmospheres, respectively. It is believed that the nitrogen atoms introduced during the RTP under nitrogen atmosphere or the oxygen precipitates facilitated by the RTP-introduced nitrogen atoms can exhibit pinning effect on the dislocation motion, which increases the critical resolved shear stress for dislocation glide.
Deep Energy Levels of Platinum-Hydrogen Complexes in Silicon
Authors: Badr Elie , Pichler Peter , Schmidt Gerhard
Published: October 2013

Hydrogen incorporated into the samples by wet chemical etching interacts with platinum and forms several energy levels in the silicon forbidden band gap. Deep-level transient spectroscopy (DLTS) on Schottky diodes reveals several platinum-hydrogen related levels in p- and n-type silicon. In the n-type silicon, two new platinum-hydrogen related levels at 0.28 and 0.41 eV below the conduction band are reported. Annealing at 377 °C results in the dissociation of their corresponding platinum-hydrogen complexes.
Polycrystalline Silicon Gettering Layers with Controlled Residual Stress
Authors: Lysáček David , Kostelník Petr , Pánek Petr
Published: October 2013

We report on a novel method of low pressure chemical vapor deposition of polycrystalline silicon layers used for external gettering in silicon substrate for semiconductor applications. The proposed method allowed us to produce layers of polycrystalline silicon with pre-determined residual stress. The method is based on the deposition of a multilayer system formed by two layers. The first layer is intentionally designed to have tensile stress while the second layer has compressive stress. Opposite sign of the residual stresses of the individual layers enables to pre-determine the residual stress of the gettering stack. We used scanning electron microscopy for structural characterization of the layers and intentional contamination for demonstration of the gettering properties. Residual stress of the layers was calculated from the wafer curvature.
Impact of Electric Field on Thermoemission of Carriers from Shallow Dislocation-Related Electronic States
Authors: Trushin M. , Vyvenko Oleg F.
Published: October 2013

Shallow dislocation-related electronic states near the bottom of the conduction band in n-type Si bonded sample have been investigated with deep-level transient spectroscopy (DLTS), isothermal transient spectroscopy (ITS) and energy-resolved DLTS. The effect of thermoemission (TE) enhancement in external electric field was found and the dependence of the TE activation energy reduction as a function of the filling grade was obtained for these states. A new model of dislocation-strain-related Poole-Frenkel effect that accounts for the own electric field of internal charge of dislocation line is suggested and compared with the experimental data.
Effect of Hydrogen for Preservation of Reconstructed Surfaces
Authors: Araki Koji , Takeda Ryuji , Izunome Koji , Zhao Xin Wei
Published: October 2013

It is well known that a smooth surface of Si wafers can be obtained by Si surface reconstruction via high-temperature annealing. However, there remains a possibility of smooth Si surfaces deteriorating by accidental oxidation (called reflow oxidation) during the unloading process, i.e., taking out Si wafers from a vertical furnace after high-temperature annealing. Therefore, we considered it important to investigate the atomic-scale effects of oxidation on surface steps and terraces on Si wafers during the unloading process. We examined the effect of unloading temperature on oxide formation on Si (100) and Si (110) surfaces. The change in surface roughness was also measured. Our results indicated a significant improvement in the root mean square values of the surface roughness of terraces on the reconstructed surface. Moreover, this improvement was dependent on the decrease in the oxidation layer thickness in the case of low-temperature unloading. Furthermore, for suppressing reflow oxidation, we replaced the injected Ar gas with H2 in the cooling process during high-temperature Ar annealing and evaluated the thickness of the reflow oxidation layer and surface structure of Si (100) and Si (110). H2 annealing during the cooling process resulted in the formation of H-terminated Si surfaces, and this formation effectively suppressed reflow oxidation. However, the H2 atmosphere also caused etching of the reconstructed Si surfaces. Atomic force microscopy measurements revealed that in spite of the etching, Si (100) and Si (110) surface roughness drastically decreased because of subsequent roughness variation, regarded as being caused by oxidation. In the case of Si (110), characteristic line oxidation was effectively suppressed, resulting in a smooth terrace-and-step structure. In summary, the obtained results suggested that our method is effective for restraining the increase in atomic-scale surface roughness due to oxidation.
Queue Time Sensitivity Analysis Methodology
Authors: Freilikhman Alex , Drori Rotem , Shor Yakov
Published: October 2013

Queue time (QT) between consecutive process-steps is one of the factors affecting the quality of current products in semiconductors industry. Identification of process steps with queue time sensitivity is not an easy and quick analysis, and it requires a high number of lots. An effective tool for a quick identification of sensitivity of a specific operation to a queue time was developed at Micron Israel and it is applied on production material. The algorithm calculates the average absolute delta of responses between consecutive step QTs, where a minimal value is accepted in steps with a linear correlation between the QT and the response. This calculation results in a snap-shot of the impact of QT for specific responses, or failures modes, for the entire production line, where the step with minimal value of this parameter is easily detected. This algorithm was used on production material and indeed helped to detect a new QT dependency in specific process steps. The Queue Time Sensitivity Analysis (QTSA) algorithm is a novel methodology to detect correlation of QT in a single process step to a certain electrical EOL failure. It can be easily implemented in a fabrication site by the IT team. QTSA methodology is very efficient in detecting QT related issues and it can be used both in routine mode on baseline material and during significant elevation in EOL or in-line failures.
Luminescence from Germanium and Germanium on Silicon
Authors: Arguirov Tzanimir , Kittler Martin , Oehme Michael , Abrosimov Nikolay V. , Vyvenko Oleg F. , Kasper Erich , Schulze Jörg
Published: October 2013

We present an overview on generation of direct gap photo- and electroluminescence in Ge bulk wafers, Ge thin films deposited on Si, and Ge p-i-n diodes prepared on Si substrates. We analyzed the emission in a spectral range from 0.45 eV to 0.95 eV, covering the radiation caused by direct gap transitions, the indirect one, and also the luminescence related to transition on dislocations. The temperature and excitation level strongly influence the intensities of direct and indirect photoluminescence in bulk samples. As it could be expected, high temperature and excitation favour the generation of direct gap luminescence. Intrinsic bulk Ge shows a quadratic dependence of the direct gap luminescence on the excitation and a sub-quadratic one for the indirect. The photoluminescence spectra taken from intrinsic Ge on Si layers show features related to dislocations. There are two spectral regions associated with dislocation recombination. At room temperature one is at around 0.45 eV and the other at 0.72 eV. We found strong direct gap radiation from the Ge p-i-n diodes with intrinsic, highly dislocated active area (dislocation density of about 108-1010 cm-2). There is a threshold current density of 8 kA/cm2, at which the direct band luminescence becomes a super-quadratic. The dependence of the radiation intensity on the excitation is governed by a power law with exponent of 1.7 before reaching that threshold and 4.5 after exceeding it. Above the threshold the dislocation radiation shows similar dependence on the excitation as the direct band luminescence.
Influences of Charged Dislocations on Performance of III-V Compound Semiconductor FinFETs
Authors: Hur Ji Hyun , Lee Myoung Jae , Cho Seong Ho , Park Young Soo
Published: October 2013

We present a model for charged dislocations effects on III-V compound semiconductor based FinFETs performance. The model is developed to obtain momentum relaxation time and, from it, key device performance parameters such as effective mobility, threshold voltage, and finally saturation drain current. We find out that charged threading edge dislocation density of a FinFET channel should be smaller than about 107 cm-2 to ignore the dislocation scattering impact on the device performance which is roughly one order more strict condition than previously known condition for wurtzite GaN.
Silicon and Oxygen in High-Al-Content AlGaN: Incorporation Kinetics and Electron Paramagnetic Resonance Study
Authors: Kakanakova-Georgieva Anelia , Nilsson Daniel , Trinh Xuan Thang , Son Nguyen Tien , Janzén Erik
Published: October 2013

The high-Al-content AlxGa1-xN alloys, x>0.70, and AlN is the fundamental wide-band-gap material system associated with the technology development of solid-state LEDs operating at the short wavelengths in the deep-UV (λ < 280 nm). Yet, their properties are insufficiently understood. The present study is intended to bring elucidation on the long-time debated and much speculated Si transition from shallow donor in GaN to a localized deep DX defect in AlxGa1-xN alloys with increasing Al content. For that purpose electron paramagnetic resonance is performed on a particular selection of high-Al-content epitaxial layers of Al0.77Ga0.23N, alternatively Al0.72Ga0.28N, alloy composition.