bluuebunny/crossref_metadata_2025 huggingface dataset:
Attachment to Minerals and Biofilm Development of Extremely Acidophilic Archaea
Authors: Zhang Rui Yong , Vera Mario , Bellenberg Sören , Sand Wolfgang
Published: October 2013

Biofilm development of F. acidiphilum BRGM4 on polycarbonate filters floating on liquid medium and pyrite surfaces were studied by confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) combined with epifluorescence microscopy (EFM). Results show that F. acidiphilum biofilms were heterogeneously distributed, and varied among different growth conditions, such as inorganic phosphate (Pi) starvation and glucose supplementation. Biofilm and planktonic cells showed significant morphological differences. Capsular EPS were observed in both biofilm and planktonic cells. Cells showed preferential attachment to the cracks/defects of pyrite surfaces.
Predicting the Metabolic Potential of the Novel Iron Oxidising Bacterium "Ferrovum" sp. JA12 Using Comparative Genomics
Authors: Mosler Sophie , Poehlein Anja , Voget Sonja , Daniel Rolf , Kipry Judith , Schlömann Michael , Mühling Martin
Published: October 2013

Here we describe the potential uptake and assimilation pathways for the essential nutrients C, N, P, and S in the acidophilic iron oxidiser Ferrovum strain JA12, a member of a novel genus among the Betaproteobacteria. Comparative genomics proved to be a powerful approach to give first insights into the biochemical potential of this novel genus and to understand the reasons for the dominating abundance of Ferrovum spp. in a pilot plant to remediate acid mine drainage.
Temporal Dynamics of Genes Involved in Metabolic Pathways of C and N of L. ferriphilum, in the Industrial Bioleaching Process of Escondida Mine, Chile
Authors: Galleguillos Pedro A. , Music Visnja , Acosta Mauricio , Salazar Camila N. , Quatrini Raquel , Shmaryahu Amir , Holmes David S. , Velásquez Antonio , Espoz Cristian , Pinilla Carlos , Demergasso Cecilia
Published: October 2013

The structure of the microbial community inhabiting the copper bioleaching heap at Escondida mine has been systematically monitored since the operation was started up (2006), using biomolecular and microbiological analyses. Recent molecular analyses showed thatL. ferriphilumwas one of the most abundant organisms in the process during year 2012. In order to study the biological dynamics of carbon and nitrogen in the process, the expression levels of thirteen genes ofL. ferriphilumwere analyzed by RT-qPCR. The 16S rRNA andalaSgenes were used as reference, and two relative quantification methods (ΔΔct and and Pffafl) were applied to estimate the relative expression levels of metabolic genes. On the day 110 of operation, a significant increment in the expression level of one gene involved in the cycle of tricarboxilic acids (2-oxoglutarate-acceptor oxidoreductase,oorA) was detected. By other hand, the expression level of two genes involved in carbohydrate metabolism (glgP, Glycogen phosphorilase, andglgA, Glycogen synthase) gradually increased, as the operation time progressed. The expression levels of genes involved in the fixation and assimilation of nitrogen increased at later stages of the process. A significant increase of the expression level of the gene annotated for Nitrogenase iron protein (nifH) was detected on the day 185 of operation. The opposite trend was observed for the gene annotated as Ammonium transporter protein (amt), as an elevated expression level was observed in earlier stages to suddenly decrease on the day 185 of operation, suggesting a change of the nitrogen source. In agreement with molecular quantitative analyses, this work confirmed thatL. ferriphilumwas an active member of the community during the period studied. This work gives new insights into biological dynamics of carbon and nitrogen, and suggests the potential guidelines to enhance the efficiency of biological components in industrial heap bioleaching processes.
Optimization of the Separation Method for Bioleaching Bacteria DNA and RNA Extracted Simultaneously
Authors: Yun Hui , Xie Jian Ping , Huang Ning , Yang Xin Jie , Xu Jing , Qiu Guan Zhou , Liu Xin Xing
Published: October 2013

DNA and RNA based analysis was a useful way to characterize microbial communities during biohydrometallurgical processes. However, feasible, affordable and efficient DNA and RNA separation methods are rarely reported although several simultaneous DNA and RNA extraction methods have been developed recently. In this study, various salts including NaCl, CaCl2 and LiCl were tested for separation of DNA and RNA. Salt concentration, nucleic acid concentration, precipitation temperature and time were optimized. The results showed that LiCl was more efficient to separate DNA and RNA than the other two salts. The optimized conditions were as follows: 1/4 volume saturated LiCl was used for precipitating RNA first at -20°C for 30 min for total nucleic acid concentration of approximately 200-400 ng/μL, and then centrifuged at 12,000×g at room temperature for 20 min to collect RNA. DNA in the supernatant was precipitated using 0.6 volume isopropanol and then collected by centrifugation at 12,000×g at room temperature for 20 min. The results indicated that DNA and RNA could be extracted from not only pure culture of Acidithiobacillus ferrooxidans(A.ferrooxidans), Acidithiobacillus caldus(A. caldus), Acidithiobacillus albertensis(A. albertensis), Leptospirillum ferrooxidans(L. ferrooxidans), Ferroplasma thermophilium(F. thermophilium), but also the acid mine drainage(AMD) water samples from Daye copper mine, Xiangxi gold mine, Axi gold mine. The resulted DNA and RNA could be amplified and A260/280 was 1.8-2.0, A260/230 was 1.8-2.2, which indicated high quality of DNA and RNA. This method could be widely used for separation of bioleaching bacteria DNA and RNA extracted simultaneously.
Heterodisulfide Reductase from Acidithiobacilli is a Key Component Involved in Metabolism of Reduced Inorganic Sulfur Compounds
Authors: Ehrenfeld Nicole , Levicán Gloria J. , Parada Pilar
Published: October 2013

Heterodisulfide reductase (Hdr), is an iron-sulfur protein which in anaerobic methanogenic archaea catalyzes the reduction of the disulphide bond between coenzyme M and coenzyme B and is coupled to methane formation. In aerobic acidophilic chemolithotrophic bacteria (e.g., biomining bacteria) the function of this enzyme is unclear. Inspection of the genomic sequences of Acidithiobacillus ferrooxidans DSM 16786 and Acidithiobacillus thiooxidans DSM 17318 and reverse transcriptase-PCR results revealed a cluster of six co-transcribed genes, hdrC1, hdrB1, hdrA, orf1, hdrC2 and hdrB2, encoding proteins with high similarity to catalytic Hdr subunits. Additionally, microarray expression profiling and quantitative RT-PCR experiments demonstrated that the hdr genes of A.ferrooxidans and A. thiooxidans were highly expressed when bacteria are grown in the presence of sulfur and tetrathionate. Moreover, hdr genes in A. ferrooxidans were greatly up-regulated when this microorganism was grown in sulfur compared to ferrous medium. These results strongly support a role for Hdr in oxidative metabolism of reduced sulfur compounds in aerobic chemolithotrophic bacteria.
Comparative Study of Fluoride-Tolerance of Five Typical Bioleaching Microorganisms
Authors: Ma Li Yuan , Li Qian , Xiao Yun Hua , Wang Qing Liang , Yin Hua Qun , Liang Yi Li , Qiu Guan Zhou , Liu Xue Duan
Published: October 2013

In the bioleaching of uranium ore, fluoride that ever accreted with the ore floats into solution, inhibiting the growth and metabolic processes of microorganism or even killing them, further reducing the efficiency of uranium leaching. In order to study the fluoride tolerance of the bioleaching microorganisms, five typical bioleaching strains includingAcidithiobacillus ferrooxidansATCC 23270,Leptospirillum ferriphilumYSK,Sulfobacillus thermosulfidooxidansST,Acidithiobacills thiooxidansA01,Acidithiobacills caldusS1 were selected to compare their growth fluctuation and their oxidation rate of iron or sulfur in the presence of different concentration of fluoride. The results showed thatAt. ferrooxidansATCC 23270 held the best fluoride tolerance, whileS. thermosulfidooxidansST took the worst. In order to explore the mechanism of microbial resistance to fluoride, whole-genome array (WGA) was used to analyze the genome-wide expression profiling ofAt. ferrooxidansATCC 23270 upon 4.8 mM fluoride stress. The results showed that gene categories closely related to fluoride tolerance include cell membrane, energy metabolism, transport and binding functions of proteins, DNA metabolism, cell processing, synthesis and transportation of protein and other functional and metabolic pathways. Most of the genes associated with iron-sulfur metabolic system ofAt. ferrooxidanswere highly expressed during 10 to 120 minutes, while in the long-term stress for 4 hours, the gene expression returned to normal level or even were down regulated. All these results provide useful information for further research on domesticating bacteria and increasing the efficiency of uranium leaching.
Estimation of Ionic Load Effect on the Oxidizing Activity of the Microbial Population in the Heap Bioleaching Process at Escondida Mine
Authors: Cautivo Dina , Soto Pamela , Zepeda Victor J. , Galleguillos Pedro A. , Velásquez Antonio , Pinilla Carlos , Demergasso Cecilia
Published: October 2013

The design of the industrial copper bioleaching plant at Escondida mine involves the recycling of the solutions in the system, with a consequent increase of ionic solutes in the raffinate solution and Pregnant Leach Solution (PLS). It is known that elevated concentrations of solutes in these solutions have a negative effect on the microbial population leading to decrease the dissolution of copper containing ore. To study the effect of the ionic load on the microbial oxidizing activity, a regression model was built using the systematic data obtained for the concentrations of sulfate, aluminum, chloride and manganese in solutions, during five years of operation. Then, this model was used to support a design of experiment (DOE). The DOE revealed an important effect on the microbial activity produced by sulfate and/or aluminum, decreasing the activity to minimum values, but the effect of chloride and manganese were not significant on the microbial oxidizing activity. This work highlights the importance of determining operational limits for the ionic load of biomining solutions in order to prevent future inhibitions of the microbial oxidizing-activity.
Bioleaching and Electrochemical Leaching of a Pyritic Chalcopyrite Concentrate
Authors: Khoshkhoo Mohammad , Dopson Mark , Sandström Åke
Published: October 2013

Moderately thermophilic bioleaching of a pyritic chalcopyrite concentrate was mimicked in an electrochemical vessel. The bioleaching was carried out for 28 days at 45°C with 2.5% (wt/vol) solid content at pH 1.5. Data from the redox potential development was used to program a redox potential controller in an electrochemical vessel to reproduce the same leaching conditions in the absence of microorganisms. Despite precipitation of iron as jarosite and formation of elemental sulphur in the electrochemical experiment, the copper recoveries were almost the same in both experiments.
Bioleaching of a Copper Sulphide Ore at Different Temperatures
Authors: Groudeva Veneta Ivanova , Iliev Mihail Vladimirov , Ilieva Ralitza Valentinova , Groudev Stoyan Nikolov
Published: October 2013

Copper sulphide ore containing 0.37% Cu, with chalcopyrite as the main copper-bearing mineral, was leached in percolation columns containing 20 kg of ore crushed to minus 20 mm at different temperatures 18, 50 and 70°C. The columns were inoculated with cultures of mesophilic, moderately thermophilic and extremely thermophilic chemolithotrophic bacteria, respectively. Different variants of leaching with respect to the composition of the leached solution and the rate of irrigation of the ore were applied at each of the temperatures above-mentioned. The best results were achieved at leaching carried out at 70°C, with periodic additions of ferric ions, nutrients and bacterial cells by leach solutions prepared in a separate BACFOX-type unit, and by application of enhanced aeration of the ore by air enriched in CO2. 82.1% of the copper was leached in this way within a period of 230 days, while the highest Cu extraction achieved at 18°C was 28.0% and that at 50°C was 55.4%, within the same period of time.
Bioleaching of Pyrrhotite by Moderately and Extremely Thermophilic Bacteria
Authors: Gu Guo Hua , Yang Hui Sha , Wang Chong Qing
Published: October 2013

Pyrrhotite ores are always mingled with very finely disseminated gold and other precious metal particles, which raise the disposal of such refractory ores to bacterial leaching level. In this paper, the bioleaching tests of pyrrhotite were carried out in Erlenmeyer flasks with moderately thermophilic Leptospirillum ferriphilum (at 40°C) and extremely thermophilic Acidianus manzaensis(at 65°C). The effects of bacterial strains, temperature, and acid tolerance on the extraction of iron were investigated, and the bioleaching residues were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that high temperature and low pH have important positive effects on the dissolution of iron under abiotic control, and extreme thermophilies are unsuitable for leaching pyrrhotite. As the pH value rapidly increased to above 4.4 and amounts of sulfur and goethite were generated at the initial stage during the process of bioleaching by A. manzaensis, the cell concentration dramatically declined. In comparison, more than 44% extraction of iron was achieved in the presence of L. ferriphilumafter four days of leaching. At the end of bioleaching, jarosite, sulfur and goethite, which could effectively block bioleaching process, were detected on the surface of residues by using XRD and SEM.
Biologically Assisted Copper Secondary Sulfide Ore Leaching in the Presence of Chloride
Authors: Davis-Belmar Carol S. , Cautivo Dina , Rautenbach George , Demergasso Cecilia
Published: October 2013

Mining operations today face a difficult challenge in terms of water availability, with most of these deposits located in arid areas where fresh water is scarce. This is especially relevant for bio-mining operations where not only the source but the water quality can be a decisive factor for its successful utilization. This research evaluates the metallurgical and microbiological performance of an adapted chloride and copper-resistant mixed culture during the leaching (laboratory scale columns) of a secondary copper sulfide at different chloride concentrations. Up to 6 g/l chloride all columns established Eh potentials over 750 mV with complete oxidation of ferrous iron in the PLS showing well established microbial activity. Copper recovery in solution, along with a high redox potential, was established faster in the mesophilic column but leveled off quickly over time. Copper extraction showed that the 6 g/l chloride column has the highest metallurgical performance (83% CuT) with 4 extra points of copper recovery over the 1.5 g/L and 3 g/l Cl- columns. These results are a good indication that comparable copper recovery rates –to the ones achieved using fresh water- can be reached in the presence of important chloride concentrations by way of using the use of a suitable and well adapted microbial population. The related process and chloride-resistant culture have been patented under the following ID N°: EP2313534/US0201095.
Effect of Temperature on Column Bioleaching of a Refractory Gold Ore
Authors: Wu Zeng Ling , Huang Zhong Sheng , Ruan Ren Man , Zhong Shui Ping , Chan Brenda K.C.
Published: October 2013

Low-grade, finely disseminated refractory sulfide gold ores associated with high arsenic are ubiquitous resources all over the world. Since heap bio-oxidation is an economic and promising biotechnology to recover gold, low grade, high organic carbon and arsenic bearing gold ores from Zhesang Mines in China were chosen for this purpose to study the key factors that would affect biooxidation. Pyrite and arsenopyrite (particle size 0.002-0.22 mm) were the main minerals from Mineral Liberation Analysis (MLA). Column biooxidation and cyanidation of mineral size < 10 mm were evaluated for its potential for gold extraction. Results showed that temperature was the main factor influencing sulfide oxidation. 58-67 % of sulfide was oxidized at 35-45°C after > 240 days of biooxidation with mixed mesophiles, while higher sulfide-S dissolution (77%) was obtained at 60°C. Sulfide-S fraction distribution revealed higher mineral decomposition, finer fractions and eventually higher sulfide oxidation at 60°C. Jarosite and scorodite were found from the residues at 60°C by SEM and EDX, which implies higher temperature accelerated arsenic precipitation. No elemental sulfur was detected during the biooxidation at 35-60°C. After bio-oxidation, column cyanidation was successfully demonstrated recovery of gold from the residues, with gold extraction rate reaching 66%.
Geobiology of In Situ Uranium Leaching
Authors: Zammit Carla , Li Kan , Etschmann Barbara , Brugger Joël , Reith Frank
Published: October 2013

Driven by the world’s thirst for energy, the demand for uranium is rapidly increasing. Hence, producers of uranium are struggling to keep up with demands and are exploring more cost-effective methods of extraction. Uranium is currently mined via open pit and underground mining as well as with in situ leaching methods, with in situ leaching currently accounting for approximately 45 % of total uranium production. Studies have shown that the presence of uranium in soils strongly affects the composition and function of resident microbial communities. In view of the close association of biological processes and uranium geochemistry, it is surprising how little information is available on the effect of microbial communities on in situ leaching. Hence, this review focuses on the possibility to exploit the properties of such microorganisms and identify opportunities to use natural microbial processes to improve uranium recovery and mine site rehabilitation.
Low Grade Copper Sulfide Ore Bioleaching in a New Bioreactor
Authors: Rivera-Santillán Rosa Elva , Patricio-Ramírez Felipe , Olvera-Pérez Irvin
Published: October 2013

Although the biological techniques application into sulfide minerals leaching to obtain valuable metals ​​is an important technological advance, the disadvantage of relatively slow kinetics bio-oxidation still limits its commercial application. However, it stimulates the research for constant improvement. Microorganisms are capable of performing their intended role with great efficiency under optimal conditions. Bioreactor design seeks to maintain certain environmental conditions that favour efficient microbial growth as pH, temperature, oxygen and carbon dioxide dissolution, stirring speed, etc. In an aerobic process such as bioleaching the optimum oxygen transference is extremely difficult to be achieved, because little oxygen dissolves in water. Furthermore the oxygen transference usually is facilitated by agitation, which is also required to mix the nutrients and maintain homogeneous solution, this transference is limited by the agitation speed because of the high power consumption, and the damage that undergoes the microorganisms submitted to excessive shear. In order to improve bio oxidation kinetics, in this paper we designed a new bioreactor, which combines elements of the stirred tank and airlift reactor, and introduces new elements, to their effective use in biohydrometallurgy. A new bio-reactor called RELBA was designed and build-up in the UNAM laboratories. It controls dissolved O2among other parameters and it prevents shear. Bioleaching tests of the ore, containing 0.135% Cu and 3.07% Fe, were performed in the orbital incubator and in theRELBAbio-reactor to 35°C using a mixed strain ofAcidithiobacilluscaldus,Acidihiobacillus thiooxidansandLeptospirillum ferriphilum, which confirm the advantages of the new bioleaching reactor.
Potassium Extraction from Biotite by Penicillium and Aspergillus
Authors: Song Miao , Pedruzzi Israel , Li Ping , Liu Jin Feng , Yu Jian Guo
Published: October 2013

Owing to lack of soluble potassium resource in some countries, it will be the competitive alternative to obtain potassium from insoluble K-bearing minerals (e.g. K-feldspar, biotite) in order to satisfy the requirements of potassium fertilizers for the agricultural sustainable development. In this work, seven fungal species including Penicillium oxalicum, P. ochrochloron, P. simplicissimum, P. spinulosum, Aspergillus niger, A. fumigatus, and A. oryzae were investigated for potassium extraction from biotite (9.64% K2O, weight fraction). Experiments were carried out in a shaker (30 °C, 180 rpm) with biotite directly dispersed in the leaching medium or enclosed in a dialysis bag. The concentrations of potassium, silicon and aluminum in the bioleaching solution were measured by Inductive Coupled Plasma (ICP), and K release amounts of biotite by seven fungal species were compared. It was found that all the strains had the abilities to enhance the dissolution of biotite, and P. oxalicum showed the highest K release amount among seven tested strains. Furthermore, the metabolites of fungi in the bioleaching process were analyzed by high performance liquid chromatography (HPLC), and the surface morphologies of biotite before and after bioleaching were characterized by Scanning Electron Microscope (SEM). The mechanism of microbial release of potassium from biotite by Penicillium andAspergillus was discussed.
Substrate Utilisation and Chalcopyrite Concentrate Bioleaching at 60°C in the Presence of Nitrate
Authors: Shiers Denis W. , Ralph David E. , Watling Helen R.
Published: October 2013

In batch cultures, the presence of nitrate inhibited iron (II) oxidation by iron (II)- or tetrathionate-adapted Acidianus (A.) brierleyi and Sulfolobus (S.) metallicus cells and tetrathionate oxidation by iron (II)-adapted A. brierleyi cells. Tetrathionate-adapted cell lines of A. brierleyi and S. metallicus oxidised tetrathionate in the presence of up to 40 mM nitrate but cell numbers were lower than those in uncontaminated tests. The results of the bioleaching tests indicated a possible window of enhanced copper extraction in the presence of 2030 mM nitrate that might be exploited in tank bioleaching. The build up of nitrate above 40 mM in bioleaching solutions must be avoided
Synthesis of Biogenic Mn Oxide and its Application as Lithium Ion Sieve
Authors: Yu Qian Qian , Morioka Emiko , Hirajima Tsuyoshi , Sasaki Keiko
Published: October 2013

Geomimetics, taking lessons from natures biogenic mineralization mechanisms, can provide powerful tools for advancing biohydrometallurgical processing. Microbial transformations are largely responsible for the Mn oxides found in nature. In this research biogenic birnessite was produced by a manganese-oxidizing fungus, Paraconiothyrium sp. WL-2, at pH 6.5 under room temperature, and characterized by XRD and TG-DTA. Abiotic (chemically synthesized) acidic birnessite was also prepared hydrometallurgically and subjected to a similar battery of characterization techniques. Following thermal treatment the sorption characteristics of these two materials were compared. The biogenic precursor showed several advantages to produce more effective Li-ion sieve than the chemically synthesized precursor. First, a shorter calcination period was required to produce Li4Mn5O12 without other phases; second, a greater content and higher crystallinity of H4Mn5O12 were obtained from the biogenic precursor. These advantages might be caused by poorer crystallinity and around 20 wt% organic matter in biogenic birnessite. While sorption density of Li+ in mmol/g was basically dependent on contents of H4Mn5O12 phase, the unique morphologies and sorption density were maintained with biogenic precursor even after repetition of sorption/desorption of Li+.
Enrichment of "Ferrovum" spp. and Gallionella Relatives Using Artificial Mine Water
Authors: Kipry Judith , Jwair Rawaa Jaffer , Gelhaar Nadja , Wiacek Claudia , Janneck Eberhard , Schlömann Michael
Published: October 2013

New acidophilic iron-oxidising bacteria likeFerrovumspp. andGallionellarelatives have recently been detected in several mine waters by culture-independent methods. To get information about their physiological characteristics, isolation of respective species is required. In former isolation studies, using a previously described iron-containing medium (iFeo) combined with the overlay-plate technique, mainlyAcidithiobacillus ferrooxidansorA. ferrivoranshad been obtained, althoughF. myxofaciensdominated the microbial community. Therefore, a new medium, called APPW was designed based on the water chemistry of a pilot plant for iron oxidation. The growth of iron-oxidising bacteria on overlay plates with iFeo and APPW media, respectively, was compared. Additionally, the iron, phosphate, and ammonium concentrations of APPW were separately adapted to iFeo. Colonies grown were analysed by PCR with primers specific forFerrovumspp.,Gallionellarelatives,Acidithiobacillusspp., andAcidiphiliumspp. While on all media most colonies obtained were contaminated by heterotrophicAcidiphiliumspp., on iFeoAcidithiobacillus, as expected, turned out to be the dominating genus among the iron oxidisers. Interestingly on APPW and APPW-NH4Ferrovumdominated among the iron oxidisers. While APPW-Fe, as compared to APPW, seemed to inhibit theGallionellarelatives, APPW-PO4resulted in an overall lower number of colonies, but a higher percentage of this taxon.
(Bio)Precipitation of Trivalent Arsenic Using an Anaerobic Bioreactor
Authors: de Matos Letícia Paiva , Freitas Patricia , Teixeira Mônica Cristina
Published: October 2013

This study aims to build and operate an experimental system to observe the metabolic activity of a mixed culture of SRB on removing sulphate and arsenic (AsIII). The experimental apparatus was operated semi-continuously. The synthetic medium utilized was modified Postgate C increased with a NaAsO2 solution (As concentrations ranging from 2 to 8 mg/L). Powdered chicken feathers (PCF) was used as nutrient and solid support for microbial growth. It is a cheap waste material produced by poultry industry and it was previously studied for As biosorption. Growth parameters analyzed were pH, Eh, sulphate and As(III) concentration. After 6 months of operation, As was introduced into the system, initially 2mg.L-1. The main results obtained are: pH changes were quit negligible, varying between 7 and 8, Eh decayed to a maximum of -400 eV, compatible with a reducing condition. Sulphate removal was of about 80%, and up to 90% of the arsenic was removed from the system. The methodology here presented is effective and innovative since arsenic is removed without any oxidation step. Considering the low cost of the waste material some operation costs may be reduced.
Enrichment and Isolation of Phosphorus Solubilizing Bacteria
Authors: Priha Outi K. , Sarlin Tuija H. , Arnold Mona E. , Kinnunen Päivi
Published: October 2013

The aim of this study was to enrich phosphorus solubilizing microorganisms from high-phosphorus iron ores, apatite ores and phosphogypsum waste. Phosphorus solubilizing microorganisms can be utilized in dephosphorization of high-phosphorus iron ores and in phosphorus leaching from fluorapatite ores. Low grade fluorapatite ore (3.6% P, pH 6.8), fluorapatite concentrate (13% P, pH 8.3), phosphogypsum waste (0.7% P, pH 2.3), iron ore 1 (0.19% P, pH 7.6) and iron ore 2 (0.18% P, pH 7.6) were used as potential sources of phosphorus solubilizing microorganisms. The samples were cultured in NBRIP media at pH 5 and 8 with either glucose or sucrose as a carbon source, and in modified 9K media at pH 1.5 and 2.5 for 3 weeks. Phosphorus solubilizing bacteria were enriched only from the fluorapatite concentrate at the pH of 8. The four obtained heterotrophic isolates were identified by 16S rRNA gene sequencing, and were shown to be closest related to Burkholderia fungorum. These results indicate that the diversity of culturable phosphorus solubilizing bacteria present in apatite and iron ores is relatively low. The isolated Burkholderia strain showed phosphorus solubilizing potential.
Biogenesis of Nanoparticles with Potential Applications as Semiconductor from Chalcopyrite Concentrate
Authors: Hosseini Mohammad Raouf , Schaffie Mahin , Pazouki Mohammad , Lotfalian Majid , Schippers Axel , Ranjbar Mohammad
Published: October 2013

Nanostructure forms of semiconductor materials are of great interest. Among these compounds, copper sulfide as a variable stoichiometric composition attracts considerable attention. In the present study, copper sulfide nanoparticles were synthesized biologically from a chalcopyrite concentratemainly containing chalcopyrite (46%) and pyrite (23%). Firstly, the copper contents of the concentrate were bioleached using thermophile bacteria, then the grownFusarium oxysporumwas added to the prepared solution and the biosynthesized nanoparticles collected and their characteristics compared with the product derived from the pure copper sulfate solution. The characterization was performed by UV spectrometry, Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetery (TG), Differential Scanning Calorimetery (DSC), Mass Spectrometery (MS), and Transmission Electron Microscopy (TEM). Finally, it wasproved that the produced nanoparticles had a covellite composition and their size was about 5-40 nm.
Static-Stiffness Analysis of a Roll-Bending Machine of High-Power
Authors: Szilágyi Attila , Takács György , Barna Balázs
Published: October 2013

This article is a brief summary of an R&D project work that includes the improvement of a roll-bending machine with high power. The emphasis was laid on achieving an increased static stiffness of the equipment. In the followings the numerical calculations and the simulations are presented.
Hard Cutting and Diamond Burnishing of 100Cr6 Steel Bearings
Authors: Líska János , Líska Katalin , Kodácsy János
Published: October 2013

The paper deals with research concerning optimal technological parameters in diamond burnishing after hard turning by standard tool geometry and by wiper geometry. Burnishing is a less known method, by which the surface of workpiece is finished by a harder tool, without chip removal. Experiments focus on the surface roughness of workpiece, at combination of feed (f) and burnishing force (Fp). We measured also machining forces (Fc, Ff, Fp) at hard turning. Workpiece was made of 100Cr6-type bearing steel with hardness of HRC64.
Study of Elastic Deformations in Hard Turning
Authors: Mičietová Anna , Neslušan Miroslav , Mrkvica Ivan
Published: October 2013

This paper deals with study of elastic deformations after hard turning of bearing steel 100Cr6. It is well known that elastic deformation could strongly affect precision of produced parts. This aspect takes a significant role during hard turning due to poor plasticity of machined material. This study presents information about elastic deformation when turning steel of different hardness and their relations to the cutting conditions. Result of this study indicates that elastic deformations are more pronounced during turning steels of high hardness and strongly depend on cutting conditions.
Research of Grinding Material Tools by Modern Grinding Wheels
Authors: Čop Jiří , Lukovics Imrich
Published: October 2013

This research paper focuses on grinding of materials used for tools (100Cr6 (CSN 4 14109), X210Cr12 ( CSN 4 19436) and epoxy resin) using grinding wheels from cubic boron nitride and diamond. The disadvantage of grinding of difficult-to-machine materials is higher wear of grinding wheels. The modern grinding wheels are able to achieve high accuracy of dimensions and high surface quality with a smaller wear of grinding wheels then grinding wheels from conventional materials. Correctly selected technological conditions are one of the most important matters to achieve the required surface quality. The main aim of this research is to determine the influence of technological conditions to quality of surface after planar grinding. The research determines the influence of the grain type of grinding wheels, feed rate and cutting depth on the quality of functional surfaces.
Laser Micro-Machining and Temperature Field Simulation
Authors: Sýkorová Libuše , Šuba Oldřich , Knedlova Jana
Published: October 2013

The parametric thermal field analyses were realized by the finite element method. The analysis was run in the software solver COSMOS/DesignSTAR thermal. The thermal module makes possible to realize cases of the thermal dependences on the material properties. Material data can be entered as a function of the temperature. The thermal and physical characteristic of the polymeric materials are changed very expressively. The output of the analysis was temperature distribution described by various colors and assigned values in the spectrogram.
Influence of the Lead Angle from the Vertical Axis Milling on Effective Radius of the Cutter
Authors: Peterka Jozef , Pokorný Peter
Published: October 2013

The submission deals with the five-axis milling at finishing process by the nose ball milling cutter. The final quality of machined surfaces is depending on many technological parameters. One of these parameters is the effective radius of cutter too. The effective radius of cutter determinates the contact line if you like the contact surface between cutter and just machined surface. In the submission is described the effect of a lead angle from the vertical axis milling on the effective radius of cutter. At last it is remitted how the change of effective radius is reflected in practice.
ANFIS Building Methodology for the Task of Cutting Tool Condition Diagnosis Using Matlab Software
Authors: Zaloha V.O. , Zinchenko Ruslan M. , Honshchyk Anna V.
Published: October 2013

Machining of materials with cutting still covers a significant part of shapegenerating operations in manufacturing process. One of the most important tasks in research touches upon the area of cutting is the development of a method which can insure: required productivity, high accuracy of machining, optimal usage of cutting tool and machine-tool resource, automation of manufacturing process, reduction of machinetool down time and cutting tool costs. In this connection cutting tool condition diagnosis (CTCD) becomes an important requirement for the realization of computer-aided manufacturing. The real-time CTCD allows improving the efficiency of machining with the opportune cutting tool replacement and the prior prevention of its catastrophic wear or breakdown. The main goal of this investigation is the verification of the ANFIS working capacity for the description of the relation between the flank wear of cutting tool and the power of vibration signal received during CTCD in turning by means of Matlab software. Consequently, the methodology of building the adaptive neuro-fuzzy inference system (ANFISnetwork) for the task of cutting tool condition diagnosis is worked out.
Stress Modelling in Curved Parts of Short Fibres Reinforced Plastic Products
Authors: Šuba Oldřich , Sýkorová Libuše , Bilek Ondrej
Published: October 2013

An investigation was carried out through a study of the influence of material anisotropy of the rounded corners of thin-walled plastic injection molded products reinforced by short-fibres, on the state of stress. It has been shown that the result of such injection-moulded processes is an anisotropic and layered product, whose mechanical behaviour differs for that of isotropic and homogenous solids. Unlike unreinforced plastics, fibre composites exhibit secondary stress effects thus need to be careful consideration in the course in designing of short fibres reinforced plastic products.
Investigation of Residual Stresses in Case of Hard Turning of Case Hardened 16MnCr5 Steel
Authors: Szabó Gergely , Kundrák János
Published: October 2013

In this paper the residual stresses are investigated emerging in the machined layer during hard turning in case of chip removal done by different tool rake angles. By means of finite element method simulation we examined what rake angle is best to complete cutting so that favourable residual stress values are gained in the machined surface layer.
Applying Projective Geometry in Design of Worm Manufacturing
Authors: Balajti Zsuzsa , Ábel József
Published: October 2013

The mathematical describing of the production process in mechanical engineer work in the euclidean space model and the base of the analytical describing of the projective space model is practically identical in the form, which makes it reasonable to discuss of the production geometry to approach of the projective geometrical negotiation in the . It is a fact that in one of the cases, using the approach of a projective geometrical connection and the mathematical-kinematical model resulted in expansion in the field of production precision, specifically considering the examination of the production of the conical worm by grinding wheel. The abstraction of the production geometry on projective space model has a few results in case of conical worms. The elliptical errors in production of the conical worm with arched or anything profile by grinding wheel can be eliminated by this method way to achieve the constant pitch, the torsion of profile and others.
The Role of Polymer Binder in Ceramic Injection Moulding
Authors: Bleyan Davit , Hausnerová Berenika
Published: October 2013

In this study thermal degradation of feedstock based on Al2O3 high compressible superground powder was investigated. The alumina powder was mixed with polymeric binders to compose the feedstock. Binder systems for CIM (Ceramic Injection Moulding) technology differed in concentration and composition of polyethylene, polyethylene glycol, low density polyethylene and waxes. The debinding and pre-sintering behavior of formulated feedstocks was characterized by thermogravimetric analysis. The results demonstrated the relationship between the feedstock thermal degradation properties and the binder system composition.
Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere
Authors: Wonaschütz A. , Coggon M. , Sorooshian A. , Modini R. , Frossard A. A. , Ahlm L. , Mülmenstädt J. , Roberts G. C. , Russell L. M. , Dey S. , Brechtel F. J. , Seinfeld J. H.
Published: October 2013

Abstract. During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm−3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from < 0.001 to 0.2, and from 2.42 to 4.96 μg m−3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.
Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability
Authors: Hamburger T. , Matisāns M. , Tunved P. , Ström J. , Calderon S. , Hoffmann P. , Hochschild G. , Gross J. , Schmeissner T. , Wiedensohler A. , Krejci R.
Published: October 2013

Abstract. First long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron particle volume, number concentrations of primary particles and particle absorption were observed. Orographic lifting and shallow convection leads to a distinct diurnal cycle at the station. It enables measurements within the lower free troposphere during night-time and observations of boundary layer air masses during daytime and at their transitional regions. The seasonal cycle is defined by a wet rainy season and a dry biomass burning season. The particle load of biomass burning aerosol is dominated by fires in the Venezuelan savannah. Increases of aerosol concentrations could not be linked to long-range transport of biomass burning plumes from the Amazon basin or Africa due to effective wet scavenging of particles. Highest particle concentrations were observed within boundary layer air masses during the dry season. Ambient sub-micron particle volume reached 1.4±1.3 μm3 cm−3, refractory particle number concentrations (at 300 °C) 510±420 cm−3 and the absorption coefficient 0.91±1.2 Mm−1. The respective concentrations were lowest within the lower free troposphere during the wet season and averaged at 0.19±0.25 μm3 cm−3, 150±94 cm−3 and 0.15±0.26 Mm−1. A decrease of particle concentrations during the dry seasons from 2007–2009 could be connected to a decrease in fire activity in the wider region of Venezuela using MODIS satellite observations. The variability of biomass burning is most likely linked to the El Niño–Southern Oscillation (ENSO). Low biomass burning activity in the Venezuelan savannah was observed to follow La Niña conditions, high biomass burning activity followed El Niño conditions.
Microphysical process rates and global aerosol–cloud interactions
Authors: Gettelman A. , Morrison H. , Terai C. R. , Wood R.
Published: October 2013

Abstract. Cloud microphysical process rates control the amount of condensed water in clouds and impact the susceptibility of precipitation to cloud-drop number and aerosols. The relative importance of different microphysical processes in a climate model is analyzed, and the autoconversion and accretion processes are found to be critical to the condensate budget in most regions. A simple steady-state model of warm rain formation is used to illustrate that the diagnostic rain formulations typical of climate models may result in excessive contributions from autoconversion, compared to observations and large eddy simulation models with explicit bin-resolved microphysics and rain formation processes. The behavior does not appear to be caused by the bulk process rate formulations themselves, because the steady-state model with the same bulk accretion and autoconversion has reduced contributions from autoconversion. Sensitivity tests are conducted to analyze how perturbations to the precipitation microphysics for stratiform clouds impact process rates, precipitation susceptibility and aerosol–cloud interactions (ACI). With similar liquid water path, corrections for the diagnostic rain assumptions in the GCM based on the steady-state model to boost accretion indicate that the radiative effects of ACI may decrease by 20% in the GCM. Links between process rates, susceptibility and ACI are not always clear in the GCM. Better representation of the precipitation process, for example by prognosticating precipitation mass and number, may help better constrain these effects in global models with bulk microphysics schemes.
Impacts of fire emissions and transport pathways on the interannual variation of CO in the tropical upper troposphere
Authors: Huang L. , Fu R. , Jiang J. H.
Published: October 2013

Abstract. Carbon monoxide (CO) is an important tracer to study the transport of fire-generated pollutants from the surface to the upper troposphere (UT). This study analyzed the relative importance of fire emission, convection and climate conditions on the interannual variation of CO in the tropical UT, by using satellite observations, reanalysis data and transport pathway auto-identification method developed in our previous study. Empirical orthogonal function (EOF) and singular value decomposition (SVD) methods are used to identify the dominant modes of CO interannual variation in the tropical UT and factors that are related to these modes. Results show that the leading EOF mode is dominated by CO anomalies over Indonesia related to El Niño-Southern Oscillation (ENSO). This is consistent with previous findings by directly evaluating CO anomaly field. Transport pathway analysis suggests that the differences of UT CO between different ENSO types over the tropical continents are mainly dominated by the "local convection" pathway, especially the average CO transported by this pathway. The relative frequency of the "advection within the lower troposphere (LT) followed by convective vertical transport" pathway appears to be responsible only for the UT CO differences over the west-central Pacific between El Niño and La Niña years.
10 yr spatial and temporal trends of PM2.5 concentrations in the southeastern US estimated using high-resolution satellite data
Authors: Hu X. , Waller L. A. , Lyapustin A. , Wang Y. , Liu Y.
Published: October 2013

Abstract. Long-term PM2.5 exposure has been reported to be associated with various adverse health outcomes. However, most ground monitors are located in urban areas, leading to a potentially biased representation of the true regional PM2.5 levels. To facilitate epidemiological studies, accurate estimates of spatiotemporally continuous distribution of PM2.5 concentrations are essential. Satellite-retrieved aerosol optical depth (AOD) has been widely used for PM2.5 concentration estimation due to its comprehensive spatial coverage. Nevertheless, an inherent disadvantage of current AOD products is their coarse spatial resolutions. For instance, the spatial resolutions of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging SpectroRadiometer (MISR) are 10 km and 17.6 km, respectively. In this paper, a new AOD product with 1 km spatial resolution retrieved by the multi-angle implementation of atmospheric correction (MAIAC) algorithm was used. A two-stage model was developed to account for both spatial and temporal variability in the PM2.5-AOD relationship by incorporating the MAIAC AOD, meteorological fields, and land use variables as predictors. Our study area is in the southeastern US, centered at the Atlanta Metro area, and data from 2001 to 2010 were collected from various sources. The model was fitted for each year individually, and we obtained model fitting R2 ranging from 0.71 to 0.85, MPE from 1.73 to 2.50 μg m−3, and RMSPE from 2.75 to 4.10 μg m−3. In addition, we found cross validation R2 ranging from 0.62 to 0.78, MPE from 2.00 to 3.01 μg m−3, and RMSPE from 3.12 to 5.00 μg m−3, indicating a good agreement between the estimated and observed values. Spatial trends show that high PM2.5 levels occurred in urban areas and along major highways, while low concentrations appeared in rural or mountainous areas. A time series analysis was conducted to examine temporal trends of PM2.5 concentrations in the study area from 2001 to 2010. The results showed that the PM2.5 levels in the study area followed a generally declining trend from 2001 to 2010 and decreased about 20% during the period. However, there was an exception of an increase in year 2005, which is attributed to elevated sulfate concentrations in the study area in warm months of 2005. An investigation of the impact of wild and prescribed fires on PM2.5 levels in 2007 suggests a positive relationship between them.