bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilization of Metabolic Citric Acid from Aspergillus niger Using Corn Starch in the Nickel Leaching of Indonesian Saprolitic Ore
Authors: Astuti Widi , Hirajima Tsuyoshi , Sasaki Keiko , Okibe Naoko
Published: December 2015

Citric acid has been proved to be the most effective organic acid for nickel extraction from nickel lateritic ores. Citric acid can be produced from fungal metabolism by utilizing several types of carbon source as fungal nutrient. In the current experiment, production of metabolic citric acid from metabolism of Aspergillus niger by using corn starch as a carbon source was investigated. The application of the citric acid produced in the leaching of nickel from Indonesian saprolitic ore under atmospheric pressure was also conducted. The optimum citric acid concentration (i.e. around 0.05 M) can be produced by using 5% w/v of corn starch after 5 days incubation of A. niger, 30°C of temperature, shaker speed of 120 rpm, and 3% v/v of methanol as an additive. The metal leaching of Indonesian saprolitic ore was conducted using <75μm of ore particle size, 5% w/v of pulp density and 200 rpm of shaker speed at different leaching temperatures (30°C, 40°C, and 60°C). The results showed that the optimum nickel recovery (around 40%) can be reached after 3 days of leaching process at 40°C. It was also found that the use of metabolic citric acid was more effective for nickel leaching compared to the use of chemical citric acid at similar citric acid concentration (i.e. 0.05 M). It can be concluded that the metabolic citric acid produced from corn starch by A. niger will be an excellent leaching reagent for extracting nickel from low-grade Indonesian saprolitic ore.
Comparison of Microbial and Geochemical Conditions of Lignite Coal Spoil and Overburden Areas and their Environmental Impact
Authors: Willscher Sabine , Schaum Maximilian , Goldammer Josef , Knippert Doreen , Kühn Denise , Ihling Heiko , Schaarschmidt Toralf
Published: December 2015

During the 20th century, Germany belonged to the world’s largest producers of lignite coal. Approaches for remediation of lignite spoil and overburden material were carried out since at least the last 50 years. Today, results of former remediation can be evaluated by their long-term effects. Coal spoil seepage waters can impact billions of m3 of ground water in involved areas for a very long time horizon (eternity impacts).
In the last years our working group had studied especially lignite coal spoil sites in the Lusatia (East Germany) with sandy substrates and faster vertical mass transport processes. In new investigations, another coal spoil site in Middle Germany with more cohesive soil substrates and layers of drift clays was studied, and geochemical and microbial parameters were characterized. The investigated site partially had a remediated topsoil layer since 40 years, and since this time agricultural cultivation of different plants (grains, legumes, Pocaceae) was performed. In this paper, data of different microbial populations in the coal spoil substrate and geochemical background data are given, and they are compared with former data of microbial communities in sandy substrates and their impact to the environment. Finally, the success of long-term remediation of such sites, the influence onto microbial life and impact to the environments will be compared and discussed.
Bioreactor Process Optimization for Bioleaching of Fine-Grained Residues from Copper Smelting
Authors: Klink Cindy , Heim Juliane , Daus Birgit , Eisen Sebastian , Schlömann Michael , Schopf Simone
Published: December 2015

Theisen sludge, a fine-grained by-product from copper smelting is a secondary resource for the winning of strategic elements by metal-oxidizing acidophilic bacteria. Screening for cultures, that grew in presence of the toxic heavy metals containing fly ash was successfully performed. Small scale experiments in shaking flasks with subsequent analysis of the pregnant leaching solution (PLS) revealed biological extraction of the major (zinc and copper) and minor metals (cobalt and rhenium). Results were confirmed by XRF analyses of the leaching residue. The bioleaching approach was up-scaled in stirred tank bioreactors under controlled conditions. Optimization of metal-extraction rates will be achieved by regulation of process-parameters, predominantly the redox-potential.
Biooxidation of a Gold-Arsenic Sulphide Concentrate by a Two-Stage Oxidation Using Consecutively Acidophilic and Neutrophilic Bacteria
Authors: Belyi A. , Solopova Natalia , Sekachev Vladimir , Teleutov Anatoliy , Malashonok Aleksandr , Krasilnikov Grigoriy
Published: December 2015

This research work has developed a processing technology for full oxidation of the biocake from gold-arsenic flotation concentrate with high pyrrhotite content by neutrophilic association of microorganisms, which oxidize elemental sulphur and antimony sulphide at a high rate. Biocake, which is produced as a result of oxidizing the sulphides in the flotation concentrate at pH 1,7 – 1,9 by acidophilic bacteria of chemolithotrophic microorganisms and containing around 3%-5% of elemental sulphur, is then fully oxidized by association of neutrophilic bacteria at рН 7,0-8,0.
Bioleaching of Chalcopyrite by Thermophilic Archaea
Authors: Song Jin Long , Liu Shuang Jiang , Jiang Cheng Ying
Published: December 2015

Bioleaching and biooxidation of sulfidicores and concentrates generate very high acidities and a great of heat, which rise the temperature in the reactors or heaps, and accumulate the sulfur on the surface of the ores. Extremely thermoacidophilic archaea, mainly from the genus ofAcidianus, Sulfolobus,Metallosphaeraandsulfurisphaera, have great potential to contribute to biomining processes for their inherent tolerance for low pH, high temperature, and high-soluble metal concentrations. Species of the genusMetallosphaeratypically grow by aerobic respiration on CO2with S0, tetrathionate (S4O62+), and Fe2+as electron donors, particularly suitble for metal extraction under high temperature by their iron- and sulfur-oxidation ability. Several species fromMetallosphaeraandAcidianusgenerawere investigated for their ability and conditions to dissolve various ores under a range of conditions. All of them showed good performance in copper extraction from chalcopyrite, with strainM.cuprinaAr-4 displaying higher activity than others. Surface analysis of chalcopyrite leached with the strain showed the leaching products accumulated on the ores. Our study will cover new understandings on the application of these thermoacidophilic archaea in biomining.
Spectroscopic and Microscopic Investigation for Biohydrometallurgy
Authors: Sasaki Keiko
Published: December 2015

In a process of bioleaching of sulfides, the surface of target mineral is sometimes covered with intermediates and final products to interfere the extraction of metal. Understanding characterization and formation order of secondary minerals, which are responsible for passivation, is a key to resolve the passivation. In the present article, identification of secondary minerals and intermediates in a process of bioleaching of several sulfides by X-ray photoelectron spectroscopy, Raman spectroscopy, identification of jarosite group minerals using Raman spectroscopy, and expectation of formation order of secondary minerals by SEM-EDX and TEM observation are overviewed. Direct observation of a nanodomain by TEM provided a useful information on amorphous secondary minerals. In bioleaching of arsenic-bearing copper sulfides, which are expected to be a new target in the near future, a passivation model was proposed to keep maximizing Cu recovery and minimizing As solubilization, based on combination of solid characterization with aqueous observation.
Enhanced Column Bioleaching of Copper Sulfides by Forced Aeration
Authors: Huang Ming Qing , Wang Yi Ming , Yin Sheng Hua , Wu Ai Xiang
Published: December 2015

To assess the effects of forced aeration on leaching dynamics of sulfides, five sets of column bioleaching of copper sulfides using Acidithiobacillus ferrooxidans were conducted when the aeration rates ranged from 0 to 150 L/h. The experimental results show that forced aeration can ameliorate the porosity and flow rates throughout the heap, and improve the bacterial concentration and oxidative ability. Forced aeration at the column bottom can enhance the interactions of air, flow and particles, and then facilitate the heap porosity and connectivity. The oxidant Fe3+ concentrations are proportional to the aeration rates, and lead to an accelerating dissolution rate of sulfides. In addition, the bacterial concentration, oxidative ability and Fe3+ concentration are susceptible to aeration rates, and the forced aeration remarkably enhances the bioleaching when aeration rates are higher than 60 L/h compare to those with none or slight aeration.
Roles of Oligotrophic Acidophiles (Alicyclobacillus) in Chalcopyrite Bioleaching System: Shake Flask Evaluation
Authors: Liu Xing Yu , Zhang Ming Jiang , Liu Wen Yan , Chen Bo Wei , Meng Chun Yu , Wen Jian Kang
Published: December 2015

An oligotrophic culture of acidophiles (Alicyclobacillus) isolated from Dexin acid mine drainage was evaluated for its synergistic effect in chalcopyrite bioleaching. Bioleaching of chalcopyrite with and without theAlicyclobacillusculture was investigated at different temperatures (33°C, 45 °C and 65 °C) and a culture-independent approach based on 16S rRNA gene clone library was used to analyze changes in the microbial community change during the bioleaching process. For 33oC leaching tests, only the bacterial community was analyzed, but for the other two temperatures, both the bacterial community and archaea communities were analyzed. Results showed that at high leaching temperature (65°C),Alicyclobacillusculture could increase copper leaching recovery from 57.83% to 60.7%. While at relative low temperature (45°C and 33°C), addingAlicyclobacillusculture inhibited copper bioleaching, copper leaching recovery decreased from 36.10% to 31.52% and from 34.02% to 21.97% respectively at 45°C and 33°C. Clone libraries analysis showed thatAlicyclobacillushelps the growth of genusSulfobacillusat 45 °C while inhibiting the growth of genusLeptospillumat both 33°C and 45 °C. Furthermore, when addingAlicyclobacillusgrowth ofFerroplasmawas limited andAcidoplasmawas facilitated at 45°C. At 60°C, addingAlicyclobacillusculture facilitated the growth of genusMetallosphaerawhile limiting the growth ofLeptospillumandFerroplasma. The results showed potential application ofAlicyclobacillusin high temperature chalcopyrite bioleaching and bioremediation of acid mine drainage.
Bioleaching of Aluminum Slags with Thermophilic Bacteria
Authors: Rivera Santillan R.E. , Patricio Ramirez F. , Aguilar Perez V.D.
Published: December 2015

The recovery of metallic aluminum from the waste generated in the production of secondary aluminum by bioleaching process using the nutrient medium MKM was investigated. The development of this project was carried out due to the need to treat waste foundry which have a major impact on the environment, using environmentally friendly techniques, such as bioleaching. At work, bioleaching of smelting slag of aluminum generated in the laboratories of the Department of Metallurgy, Faculty of Chemistry, UNAM, was reported. Tests were conducted using thermophilic microorganisms at 70°C in an orbital incubator at natural pH, obtaining metallic clean aluminum, aluminum in solution and salts solution. The pH, bacterial growth and redox potential were monitored daily. We conclude that bioleaching of aluminum slags is feasible. The lack of information about the treatment of this type of industrial waste, makes this research is pioneer in this field.
Reductive Leaching of Jarosites by Shewanella putrefaciens - Influence of Humic Substances and Chelators in Mineral Dissolution
Authors: Castro Laura , Muñoz J.A. , González F. , Blázquez M. Luisa , Ballester Antonio
Published: December 2015

The anaerobic bioreduction of three Fe (III) ores by a type strain of Shewanella putrefaciens has been investigated. The release of ferrous ion indicated the microbial reduction of jarosite and promotes the subsequent secondary mineralization, leading to the formation of various iron-nearing minerals. In addition, the influence of citrate and EDTA in the medium acting as chelating agents, and an electron shuttling molecule were studied. While the citrate and humic substances increased the iron reduction rate, AQDS inhibit the mineral bioreduction and dissolution. S. putrefaciens do not have the necessity of the direct contact between cells and jarosites and, in consequence, cell attachment and biofilm formation on the mineral surface is scant.
Study of Microorganism Trench-Leaching of a Chinese High Fluorine-Bearing Uranium Ore
Authors: Mo Xiao Lan , Wen Jian Kang , Xu Cheng Yan , Wu Biao , Chen Bo Wei , Shang He
Published: December 2015

The microorganism trench-leaching process of a low-grade uranium ore with a high content of fluorine was experimentally studied through the technique of Real-time PCR by using the fluorine-tolerance bacteria of Retech-3 as the leaching-ore bacteria. It was found that the Retech-3 strains of fluorine-tolerance domestication grown well in a fluoride solution with concentration of 0.0~3.0 g·L-1, and the oxidation of Fe2+ ions to Fe3+ ions occurred rapidly to promote the extraction of uranium. The experimental results showed that the bioleaching rate (89.82%) of uranium can be improved of 13.80% than acid leaching in 30 days with 65 kg ore and its particle size of-6 mm (fraction of 100%) in trench. The Real-time PCR analysis of microbial population compositions revealed that Retech-3 strains were mainly composed of Leptospirillum sp. and Acidithiobacillus sp. in the leaching process. The obvious improvements of fluorine-tolerance domestication of bacteria and the uranium leaching process will provide fundamentals for the smooth utilization of a high fluorine-containing uranium ore with the aid of microorganism trench-leaching.
Influence of Bacterial Detachment on the Bioflotation of Malachite
Authors: Kim Ga Hee , Park So Yeon , Park Kyuh Yeong , Choi Junh Yun , Choi Si Young Q. , Kim Seung Kon , Kim Hyun Jung
Published: December 2015

The effects of the bacterial growth phase on the malachite flotation were investigated in a well-controlled Hallimond tube system. Rhodococcus opacus, which is one of representative hydrophobic bacteria, was employed for this study. The test results showed that the bacteria in the stationary phase exhibit two-fold greater floatability than those in mid-exponential phase. To understand the observed flotation behavior, complementary cell characterization tests (e.g., zeta potential and contact angle measurements) and cell attachment tests were conducted. Interestingly, the bacteria at both phases exhibited similar surface properties as well as almost identical amount of cells attached onto the malachite, suggesting that the growth phase dependent flotation behavior cannot be attributed to the variation of cell surface properties and the extent of cell adsorption. On the other hand, cell detachment tests revealed that the amount of cells detached from the malachite surface is greater for the mid-exponential phase than the stationary phase due to the higher fluid drag applied to the cells at the mid-exponential phase, which was explained by the differences in the size and shape of attached bacteria onto the malachite surface. Specifically, the bacteria in the mid-exponential phase had a larger size and formed loosely-packed structures like an end-to end on the malachite surface. These morphological characteristics were found to cause the bacteria of mid-exponential phase to be separated highly sensitive and easy from malachite surface due to the fluid flow. The findings from this study suggest that in the case of bioflotation using a relatively large bacteria size than the collector, it is important to consider the cell detachment by the fluid flow that occurs during a flotation process.
Isolation and Selection of Halophilic Ureolytic Bacteria for Biocementation of Calcium and Magnesium from Seawater
Authors: Arias Dayana , Valdes Patricia , Cisternas Luis A. , Rivas Mariella
Published: December 2015

Antofagasta the second region of Chile is known worldwide for its extensive mining activity, mainly in the production of copper, molybdenum, iodine and lithium. It is also one of the driest areas of the world with few sources of fresh water that in addition to the current increase in the development of mining projects, it has generated a strong necessity for sea water uses in industrial processes. Recently some mining companies are evaluating the use of seawater in various processes, including mineral flotation. However, they have determined a low metallurgical recovery mainly of Mo, due to the effect of secondary ions as calcium, magnesium, sulfate and bicarbonate present in sea water, which precipitate at alkaline pH and produce colloids that interfere in flotation.As a biotechnology alternative to increase the recovery of valuable species by flotation in seawater, it has been isolated and characterized selected native halophilic bacteria in the Atacama Desert, which used urea as a source of energy to produce ammonia and CO2. The ammonia increases the pH of carbonate generating means, which provides favorable conditions for the formation and precipitation of Ca and Mg carbonates and secondary ions presented in high concentration in seawater.The results show that from the total isolates, 22% has proven urease activity by the method of Christensen and phenolphthalein. Furthermore, isolates were evaluated for their ability to precipitate these ions by biocementation assay. Those bacterial isolates that precipitate these ions faster were identified phylogenetically and urease activity and microbial kinetics were quantified. Finally the obtained crystals were subjected to electron scanning microscopy and X-ray diffraction determining the morphology of the crystals production and mineralogical composition.
Thermodynamic Modelling of Geo-Biometallurgical Oxidation of Sulfide Ores
Authors: Gudkov Sergey S. , Yemelianov Yuri Ye. , Shketova Luidmila Ye. , Kopylova Natalia V. , Afonina Tatiana Yu.
Published: December 2015

Heap bioleaching of sulfide ores (geotechnology) simulates naturally occurring processes when sulfides convert to oxides. This process is environmentally-friendly. Gold-bearing sulfide ore from a Russian deposit was studied. The samples were composed of quartz (38-48%), feldspars (22-24%) and micaceous minerals (18-21%). Carbonates occurred as ankerite, calcite, dolomite and siderite. The host minerals were pyrite (2.2-2.3%) and arsenopyrite (1.2-1/7%). The grade of gold was 1.6-2.0 g/t. Russian software package Selector was used to develop the model. Thermodynamics of the reaction pathway for the conversion of the gold-bearing sulfide ore in H2SO4 environment with and without using bacteria was calculated. Phases and their components which are able to form in these given conditions were selected during modeling. Modeling of irreversible evolution of the rocks caused by bacteria was carried out in the three reservoir system. They are interconnected by the flows of three movable phases: gases, solid phase and liquid phase. In this case, the composition of the solutions which were obtained under steady state conditions without bacteria and metastable equilibrium using bacteria can be compared. Bacterial oxidation occurs under acidic conditions. Oxidation without using bacteria occurs under more alkaline conditions. Bacteria increase the rate of sulfides oxidation and retard the formation of mixed-layer aluminum silicates (illites, montmorillomonites) and carbonates (magnesian calcite). It was found that bacteria have the potential to achieve the required destruction of sulfides in favorable environment. Bacteria make the rate of sulfide oxidation higher. In the presence of bacteria, the rate of aluminosilicates oxidation is slower compared to the conditions without using bacteria. Mineralogical analyses of the leach products confirmed this. Results show that thermodynamic approach can be successfully used for the modeling of bacterial-oxidation circuits and geology of the rocks and ores.
Bioremediation and Metal Resistant Bacteria in a Closed, Cold Northern Mine
Authors: Bomberg Malin , Arnold Mona , Kinnunen Päivi
Published: December 2015

Heavy metals, e.g. copper and nickel, are released to the environment as a result of mining activities. Heavy metals are required by most living organisms as trace elements, but in excess they are toxic and cause considerable environmental stress. Microbes have developed different strategies to tolerate otherwise toxic conditions. In the surroundings of closed Kotalahti Mine the concentrations of copper and nickel in the water have earlier been highly elevated. In order to decrease the concentrations of heavy metals and increase water pH, manure sludge was added to the flooded mine pit. Thisin situbioreactor has operated successfully for 15 years after the treatment. The current concentrations of heavy metals are generally low. Nevertheless, resistance genes for copper (copA), cadmium-nickel (cnrA), nickel-cadmium-cobalt (nccA) and cadmium-zink (czcA) could still be found in the microbial community of the flooding water.
Isolation and Characterization of Toxic Metal Removing Bacterial Bioflocculants
Authors: Karthiga Devi K. , Natarajan K.A.
Published: December 2015

Toxic metal pollution of ground and surface waters occur due to mining, mineral processing and metal extraction processes. Acid mine drainage emanating from abandoned mines and processed tailings and mined ore burdens also contribute to heavy metal pollution of water bodies. Bacterial bioflocculants are known to be useful in waste water treatment and exhibit higher metal removal efficiencies even at low metal concentrations. Bioflocculant generation from three types of bacterial strains, namely,Bacillus licheniformis, Bacillus firmusandBacillus megateriumwas studied and optimized. The bacterial bioflocculants were characterized using Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC) and Thin layer chromatography (TLC). Flocculation efficiencies of different bioflocculants were established with respect to clay and hematite suspensions and compared. Use of the bioflocculants in the removal of toxic metals such as chromium and arsenic was established as a function of solution pH, metal concentration, time and flocculant dosage.
Microbially Supported Recovery of Precious Metals and Rare Earth Elements from Urban Household Waste Incineration Slag
Authors: Muehe E. Marie , Schmidt Caroline , He Jing , Helle Thomas , Kappler Andreas
Published: December 2015

The use of precious metals and Rare Earth Elements in electronic, medical, and automobile industries is drastically increasing. To meet this demand and to escape the financial pressure of the global metal market, not only mining activities but recently also the recovery of these elements from industrial and urban household waste is in the focus of research. It has been shown that the application of extracting solutions with pH values lower than 4 lead to an economically feasible recovery of industrially precious metals. It is unclear, however, whether and to which extent this abiotic extraction efficiency can potentially be increased by using microorganisms capable of dissolving more stable minerals at low pH. The goal of this project therefore is to first view urban household waste as a resource for metals and evaluate combined abiotic and biotic extraction procedures for an increase in metal extraction efficiency.
Natural Organic Matter Affects the Treatment of Mine Tailings through Bioleaching Processes
Authors: Silva René A. , Park Jeong Hyun , Hong Jeong Sik , Kim Hee Jae , Park Jay Hyun , Kim Hyun Jung
Published: December 2015

In the present study, the effects of natural organic matter (NOM) on metal bioleaching from mine tailings were investigated. NOM can enter into the bioleaching process either through mine tailings being exposed in the natural ground surface conditions or through the water quality in the bioleaching process. An analysis of the conditions resembling the interaction between NOM and mine tailings was conducted through the variation of the concentration of suspended NOM (0, 20, 50 ppm) and the amount of NOM (0, 20, 50 ppm) attached to the mine tailings surface. Different concentrations of Suwannee River Humic Acid (SRHA) were considered as the main source of NOM for the bioleaching experiments. The flask experiments were conducted using bacterial cultures of Acidithiobacillus ferrooxidans (1x107 cells/mL) grown in DSMZ medium 882 at a constant temperature of 30 °C, shaking speed of 150 rpm, and 1.8 as initial pH. The solid concentration was fixed at 0.5 % w/v of mine tailings (particle size of 100-150 µm), which were obtained from Janggun Mine, Gyeongsang, South Korea. No differences in extraction efficiency were observed in relation to variation of NOM concentration (0–50 ppm SRHA) attached to the surface of mine tailings. On the other hand, a reduction of approximately 10% to 15% of metal bioleaching efficiency (Zn) was observed due to the increment of suspended NOM concentrations, 20 and 50 ppm of SRHA, respectively.
Acid Leaching of Cu and Zn from a Smelter Slag with a Bacterial Consortium
Authors: Tuovinen Olli H. , Särkijärvi Silja , Peuraniemi Esa , Junnikkala Saku , Puhakka Jaakko A. , Kaksonen Anna H.
Published: December 2015

This study was undertaken to determine the leaching of Cu and Zn from a smelter slag in acidic, sulfate-rich solutions with, and without, mesophilic Fe-and S-oxidizing bacteria. Cu in the slag was mostly distributed in fayalite, Fe-deficient Cu-sulfides and metallic Cu, and Zn was associated with fayalite, magnetite and glassy silicates. The test culture was enriched from acid mine water using mineral salt growth media supplemented with 4.5 g Fe2+ L-1 and 10 g S0 L-1. The bioleaching experiments were carried out in shake flasks at 27 °C and chemical controls were included. The slag sample was pre-leached for 24 h to partially satisfy the acid demand before the leaching experiments at 10% pulp density. In the bioleaching experiments, 69-83% Cu and 4.1-14% Zn were dissolved in 25 days at pH 2.0-2.2. The highest extent of bioleaching was with S0 as the substrate. The efficiency of the bioleaching depended on H2SO4 generation from the added S0. The activities of the bacteria were not adversely affected by the dissolved metals. The maximum yields of chemical leaching were 68% Cu and 3.7% Zn.
Biotechnological Recovery of Valuable Metals from Lignite Ash
Authors: Hedrich Sabrina , Bellenberg Sören , Kermer René , Gehrke Tilman , Sand Wolfgang , Schippers Axel , Reichel Susan , Glombitza Franz , Janneck Eberhard
Published: December 2015

Ashes from lignite combustion for power generation contain considerable amounts of strategic metals, metalloids and rare earth elements. Within the presented project bioleaching with different types of microorganisms was investigated to recover valuable metals from lignite ashes. An increased mobilization of several metals ions was observed with the gluconic acid-producing bacteriumAcetobacter methanolicusand the silicate-solubilizing bacteriumBacillus circulans. Most promising results were achieved with sulfuric acid-producing microorganisms and bioleaching could even be increased at higher temperatures or by reductive bioleaching using acidophilic, iron-reducing bacteria.
Research Progress on Recovering Valuable Metals from Wasted Circuit Board by Bio-Hydrometallurgy Technology
Authors: Lin Hai , Dong Ying Bo , Wang Xin
Published: December 2015

The quantity of circuit boards produced and abandoned has increased with the development of electronics industry. The wasted circuit board has the characters of large amounts, high metal content and harmful to environment, which is known as “urban mines”. The effective recycling of the valuable metals in wasted circuit boards had always been the focus. The characteristics of pyrometallurgical recovery, mechanical recovery and wet recovery, such as low recovery ratio, high cost and environmental pollution fails to recover the precious metals from wasted circuit board. This paper outlines the research progress of using the microbiological method to recycle the metal from waste circuit boards, including the type of main used microbe, reaction mechanism and influencing factors and so on. Additional, this paper discusses the research status about taking advantage of the microbiological method to recycle the metals with high economic value. Finally, it discusses the research direction and prospect of this recycling method.
Biosorptive Removal of Hexavalent Chromium from Aqueous Industrial Solutions by a Novel Wood Apple Shell Powder Biomass
Authors: Itankar Nilisha , Patil Yogesh
Published: December 2015

A novel wood apple shell powder (WASP) biomass was used to remove Cr(IV) from aqueous solutions. Study revealed that WASP removed 50 mg/l of Cr(VI) with >99% efficiency. Optimum parameters for maximum biosorption were: pH 2-4, contact time 60 min and biomass quantity 1g/10 ml. Interestingly, it was observed that loading capacity of WASP was higher as compared to conventional activated charcoal. Equilibrium sorption capacity of WASP increased with increasing initial concentration of Cr(VI) from 5-300 mg/L. Biosorption by WASP conformed to the Langmuir and Freundlich adsorption isotherms. Desorption of Cr(VI) took place with >80% efficiency. Continuous mode study in packed bed column showed that WASP has immense potential as “biomaterial” for the removal/recovery of Cr(VI) from aqueous industrial solutions.
Biofilm Formation and Stainless Steel Corrosion Analysis of Leptothrix discophora
Authors: Thyssen Christian , Holuscha David , Kuhn Jens , Walter Friederike , Fürbeth Wolfram , Sand Wolfgang
Published: December 2015

Bioleaching and biocorrosion are based on similar biochemical processes. Microbe-surface interaction, biofilm formation and concomitant extracellular polymeric substance (EPS) production gained increasing interest in the past decades. Nowadays it is generally accepted that biofilm formation and an accompanying formation of manganese oxides by manganese oxidizing bacteria such as Leptothrix spp. account for one type of pitting corrosion of stainless steel (SS). However, little is known about biofilm formation, EPS composition of manganese oxidizing microorganisms and their influence on microbiologically influenced corrosion. Consequently, we studied biofilm formation of Leptothrixdiscophora, the biooxidation of manganese in biofilms on floating filters as well as biofilm formation on stainless steel and the involved corrosion processes. Cells were visualized by epifluorescence (EFM) or confocal laser scanning –microscopy (CLSM). Additionally, the influence of biofilm formation and biooxidation of manganese by L. discophora on the open circuit potential (OCP) and pitting potential (Epit) of stainless steel was measured using a 3 electrode setup. L. discophora grew well in biofilms on floating filters and on SS coupons and incorporated in both conditions Mn2+ in the form of MnO2 from the bulk phase into the biofilm. OCP measurements of actively manganese-oxidizing biofilms on stainless steel showed a significant ennoblement of ≥200 mV.
Fabrication and Characterization of Graphene Field Effect Transistor: Study of Interfacial Effects for Device Reliability
Authors: Prasad Neetu , Kumari Anita , Bhatnagar P.K. , Mathur P.C.
Published: December 2015

In the present work, we report fabrication and electrical characterization of a back gated graphene field effect transistor (GFET). We have focused our study on the interfacial effect (graphene/SiO2) on the performance of the device. Hysteresis was observed in the drain conductance when measured with respect to dual gate sweep voltage, which increases with increasing sweeping voltage range. The conductance was observed to increase with increase in temperature but there was no reduction in the hysteresis. This proved that temperature annealing could improve the channel conductivity but not the interfacial effects. Further, a metal oxide semiconductor (MOS) device was fabricated with SLG inserted in between the metal and oxide layer and its capacitance-voltage (C-V) characteristics were studied. A small series capacitance (2.1 nF) was observed to be existing in series with the oxide capacitance (4.5 nF) which was attributed to the trap states at the interface of graphene and SiO2­ layer. Also, the flat band voltage was not affected by the incorporation of graphene layer in the MOS device indicating no change in the work function of the metal gate (Cr/Au). This is an advantageous situation where graphene does not alter its work function also being impermeable, restricts the diffusion of metal particles through the SiO2.
Insect assemblages associated with the exotic riparian shrub Russian olive (Elaeagnaceae), and co-occurring native shrubs in British Columbia, Canada
Authors: Collette Liana K.D. , Pither Jason
Published: December 2015

Russian olive (Elaeagnus angustifolia Linnaeus; Elaeagnaceae) is an exotic shrub/tree that has become invasive in many riparian ecosystems throughout semi-arid, western North America, including southern British Columbia, Canada. Despite its prevalence and the potentially dramatic impacts it can have on riparian and aquatic ecosystems, little is known about the insect communities associated with Russian olive within its invaded range. At six sites throughout the Okanagan valley of southern British Columbia, Canada, we compared the diversity of insects associated with Russian olive plants to that of insects associated with two commonly co-occurring native plant species: Woods’ rose (Rosa woodsii Lindley; Rosaceae) and Saskatoon (Amelanchier alnifolia (Nuttall) Nuttall ex Roemer; Rosaceae). Total abundance did not differ significantly among plant types. Family richness and Shannon diversity differed significantly between Woods’ rose and Saskatoon, but not between either of these plant types and Russian olive. An abundance of Thripidae (Thysanoptera) on Russian olive and Tingidae (Hemiptera) on Saskatoon contributed to significant compositional differences among plant types. The families Chloropidae (Diptera), Heleomyzidae (Diptera), and Gryllidae (Orthoptera) were uniquely associated with Russian olive, albeit in low abundances. Our study provides valuable and novel information about the diversity of insects associated with an emerging plant invader of western Canada.
Third phase of cardiac rehabilitation: a nurse-based â€œhome-controlâ€ model
Authors: Albertini Sara , Ciocca Antonella , Opasich Cristina , Pinna Gian Domenico , Cobelli Franco
Published: December 2015

Background. Phase 3 is a critical point for cardiac rehabilitation: many problems donâ€™t allow achieving a correct secondary prevention, in particular regarding the relationship between patient and cardiologist. Aiming at ensuring continuity of care of phase 3 cardiac rehabilitation patients, we have developed a telemetric educational program to stimulate in them the will and capacity to become active co-managers of their disease. Methods. Nurses specialized in cardiac rehabilitation, with the collaboration of the general practitioners, contact the patients by scheduled phone calls to collect questionnaires about their health status and the result of biochemistry. All the results are analyzed by the nurses and discussed with each patient (educational reinforcement). The effects of this program of co-management of cardiac disease and secondary prevention are analyzed comparing each patient data at the discharge with data after one year and those coming from our archive (retrospective analysis). Results. The patients enrolled in this study pay much more attention to the amount of food they eat; they tend not to gain weight, and they restart smoking in a reduced proportion compared to patients not enrolled in the study. However, despite having received better information on their cardiac disease, their compliance to physical training, consumption of healthy food, and pharmacological therapy is not improved. Conclusions. This study focuses on the role of a continuous educational program of a cardiac rehabilitation unit after the patientâ€™s discharge. This home control program conducted by nurses specialized in cardiac rehabilitation, with the assistance of cardiologists, psychologists and physiotherapists, and in collaboration with the general practitioner, was quite cheap, and helped maximizing the knowledge of the disease and reinforcing correct life style in the patients. The results are not as good as expected, probably because one year does not represent a sufficient time, or because the educational intervention needs to be improved.
The T.O.S.CA. Project: Research, Education and Care
Authors: Bossone Eduardo , Limongelli Giuseppe , Malizia Graziella , Ferrara Francesco , Vriz Olga , Citro Rodolfo , Marra Alberto Maria , Arcopinto Michele , Bobbio Emanuele , Sirico Domenico , Caliendo Luigi , Ballotta Andrea , Dâ€™Andrea Antonello , Frigiola Alessandro , Isgaard Jorgen , SaccÃ  Luigi , Cittadini Antonio
Published: December 2015

Despite recent and exponential improvements in diagnostic- therapeutic pathways, an existing â€œGAPâ€ has been revealed between the â€œreal world careâ€ and the â€œoptimal careâ€ of patients with chronic heart failure (CHF). We present the T.O.S.CA. Project (Trattamento Ormonale dello Scompenso CArdiaco), an Italian multicenter initiative involving different health care professionals and services aiming to explore the CHF â€œmetabolic pathophysiological modelâ€ and to improve the quality of care of HF patients through research and continuing medical education.
Happy Birthday! Two centuries of the New England Journal of Medicine
Authors: Scardi Sabino
Published: December 2015

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Эллиптическая параметризация пфаффовых интегрируемых иерархий в пределе нулевой дисперсии
Authors: Akhmedova Valeriya Eduardovna , Zabrodin Anton Vladimirovich
Published: December 2015

Показано, что бездисперсионные пределы пфаффовой иерархии Кадомцева-Петвиашвили (также известной как пфаффова решетка и $DКП$) и пфаффовой иерархии Тоды допускают переформулировку в терминах эллиптических функций. В эллиптической форме они выглядят как эллиптические деформации бездисперсионных иерархий Кадомцева-Петвиашвили и двумеризованной цепочки Тоды соответственно.
Билинейные уравнения для строгой иерархии Кадомцева-Петвиашвили
Authors: Helminck Gerard F , Panasenko Elena Aleksandrovna , Polenkova Svetlana Vladimirovna
Published: December 2015

Описаны два модуля алгебры $Psd$ псевдодифференциальных операторов; для каждого из них определена ассоциированная система, из которой можно получить как условия совместности уравнения Лакса для строгой иерархии Кадомцева-Петвиашвили. На этих модулях построено множество билинейных уравнений, характеризующие решения строгой иерархии Кадомцева-Петвиашвили, которые получаются одеванием базисного образующего элемента алгебры $Psd$.
Seroprevalence of Asian Lineage Chikungunya Virus Infection on Saint Martin Island, 7 Months After the 2013 Emergence
Authors: Gay Noellie , Rousset Dominique , Huc Patricia , Matheus Séverine , Ledrans Martine , Rosine Jacques , Cassadou Sylvie , Noël Harold
Published: December 2015

At the end of 2013, chikungunya virus (CHIKV) emerged in Saint Martin Island, Caribbean. The Asian lineage was identified. Seven months after this introduction, the seroprevalence was 16.9% in the population of Saint Martin and 39.0% of infections remained asymptomatic. This moderate attack rate and the apparent limited size of the outbreak in Saint Martin could be explained by control measures involved to lower the exposure of the inhabitants. Other drivers such as climatic factors and population genetic factors should be explored. The substantial rate of asymptomatic infections recorded points to a potential source of infection that can both spread in new geographic areas and maintain an inconspicuous endemic circulation in the Americas.
Molecular Characterization of Extended-Spectrum β-Lactamase-Producer Klebsiella pneumoniae Isolates Causing Neonatal Sepsis in Peru
Authors: García Coralith , Astocondor Lizeth , Rojo-Bezares Beatriz , Jacobs Jan , Sáenz Yolanda
Published: December 2015

Klebsiella pneumoniae (KP) is the most common cause of neonatal sepsis in the low- and middle-income countries. Our objective was to describe the phenotypic and molecular characteristics of extended-spectrum β-lactamase (ESBL)-producer KP in neonatal care centers from Peru. We collected 176 non-duplicate consecutive KP isolates from blood isolates of neonates from eight general public hospitals of Lima, Peru. The overall rate of ESBL production was 73.3% (N = 129). The resistance rates were higher among ESBL-producer isolates when compared with the nonproducers: 85.3% versus 12.8% for gentamicin (P < 0.01), 59.7% versus 8.5% for trimethoprim–sulfamethoxazole (P < 0.01), 45.0% versus 8.5% for ciprofloxacin (P < 0.01), and 36.4% versus 12.8% for amikacin (P < 0.01). A total of 359 β-lactamase-encoding genes were detected among 129 ESBL-producer isolates; 109 isolates (84.5%) carried two or more genes. Among 37 ESBL-producer isolates randomly selected, CTX-M-15 and CTX-M-2 were the most common ESBLs detected. Most of the isolates (92%) belonged to the group KpI. Pulsed-field gel electrophoresis showed that multiple KP clones were circulating among the eight neonatal units included.
Clinical Attack Rate of Chikungunya in a Cohort of Nicaraguan Children
Authors: Balmaseda Angel , Gordon Aubree , Gresh Lionel , Ojeda Sergio , Saborio Saira , Tellez Yolanda , Sanchez Nery , Kuan Guillermina , Harris Eva
Published: December 2015

Chikungunya virus (CHIKV) was recently introduced into the Americas. In Nicaragua, the first endogenous transmission of CHIKV was recognized in September 2014. We used an ongoing dengue cohort study of children aged 2–14 years in Managua, Nicaragua, to document the attack rate of symptomatic chikungunya in a presumably naive population. From September 2014 through March 2015, the overall clinical attack rate of laboratory-confirmed CHIKV infection was 2.9% (95% confidence interval [CI]: 2.3%, 3.4%). The attack rate was greater in children ≥ 8 years of age (4.1%; 95% CI: 3.2%, 5.1%) than in those < 8 years of age (1.5%; 95% CI: 0.9%, 2.1%). The mean age of CHIKV cases presenting with typical chikungunya symptoms was 9.8 years, compared with 7.8 years for cases presenting with undifferentiated fever (P = 0.04). Our data suggest that the clinical attack rate in children may underestimate the true burden of disease as some children, especially young children, may experience more atypical symptoms (e.g., undifferentiated fever).
The origin of midlatitude ice clouds and the resulting influence on their microphysical properties
Authors: Luebke A. E. , Afchine A. , Costa A. , Meyer J. , Rolf C. , Spelten N. , Avallone L. M. , Baumgardner D. , Krämer M.
Published: December 2015

Abstract. The radiative role of ice clouds in the atmosphere is known to be important, but uncertainties remain concerning the magnitude and net effects. However, through measurements of the microphysical properties of cirrus clouds, we can better characterize them, which can ultimately allow for their radiative properties to be more accurately ascertained. It has recently been proposed that there are two types of cirrus clouds – in situ and liquid origin. In this study, we present observational evidence to show that two distinct types of cirrus do exist. Airborne, in situ measurements of cloud ice water content (IWC), ice crystal concentration (Nice), and ice crystal size from the 2014 ML-CIRRUS campaign provide cloud samples that have been divided according to their origin type. The key features that set liquid origin cirrus apart from the in situ origin cirrus are a higher frequency of high IWC (> 100 ppmv), higher Nice values, and larger ice crystals. A vertical distribution of Nice shows that the in situ origin cirrus clouds exhibit a median value of around 0.1 cm−3, while the liquid origin concentrations are slightly, but notably higher. The median sizes of the crystals contributing the most mass are less than 200 μm for in situ origin cirrus, with some of the largest crystals reaching 550 μm in size. The liquid origin cirrus, on the other hand, were observed to have median diameters greater than 200 μm, and crystals that were up to 750 μm. An examination of these characteristics in relation to each other and their relationship to temperature provides strong evidence that these differences arise from the dynamics and conditions in which the ice crystals formed. Additionally, the existence of these two groups in cirrus cloud populations may explain why a bimodal distribution in the IWC-temperature relationship has been observed. We hypothesize that the low IWC mode is the result of in situ origin cirrus and the high IWC mode is the result of liquid origin cirrus.
Verification of the multi-layer SNOWPACK model with different water transport schemes
Authors: Wever N. , Schmid L. , Heilig A. , Eisen O. , Fierz C. , Lehning M.
Published: December 2015

Abstract. The widely used detailed SNOWPACK model has undergone constant development over the years. A notable recent extension is the introduction of a Richards equation (RE) solver as an alternative for the bucket-type approach for describing water transport in the snow and soil layers. In addition, continuous updates of snow settling and new snow density parameterizations have changed model behavior. This study presents a detailed evaluation of model performance against a comprehensive multiyear data set from Weissfluhjoch near Davos, Switzerland. The data set is collected by automatic meteorological and snowpack measurements and manual snow profiles. During the main winter season, snow height (RMSE: < 4.2 cm), snow water equivalent (SWE, RMSE: < 40 mm w.e.), snow temperature distributions (typical deviation with measurements: < 1.0 °C) and snow density (typical deviation with observations: < 50 kg m−3) as well as their temporal evolution are well simulated in the model and the influence of the two water transport schemes is small. The RE approach reproduces internal differences over capillary barriers but fails to predict enough grain growth since the growth routines have been calibrated using the bucket scheme in the original SNOWPACK model. However, the agreement in both density and grain size is sufficient to parameterize the hydraulic properties successfully. In the melt season, a pronounced underestimation of typically 200 mm w.e. in SWE is found. The discrepancies between the simulations and the field data are generally larger than the differences between the two water transport schemes. Nevertheless, the detailed comparison of the internal snowpack structure shows that the timing of internal temperature and water dynamics is adequately and better represented with the new RE approach when compared to the conventional bucket scheme. On the contrary, the progress of the meltwater front in the snowpack as detected by radar and the temporal evolution of the vertical distribution of melt forms in manually observed snow profiles do not support this conclusion. This discrepancy suggests that the implementation of RE partly mimics preferential flow effects.