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Sample records for superior metal selectivity

  1. Superior metallic alloys through rapid solidification processing (RSP) by design

    Energy Technology Data Exchange (ETDEWEB)

    Flinn, J.E. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States)

    1995-05-01

    Rapid solidification processing using powder atomization methods and the control of minor elements such as oxygen, nitrogen, and carbon can provide metallic alloys with superior properties and performance compared to conventionally processing alloys. Previous studies on nickel- and iron-base superalloys have provided the baseline information to properly couple RSP with alloy composition, and, therefore, enable alloys to be designed for performance improvements. The RSP approach produces powders, which need to be consolidated into suitable monolithic forms. This normally involves canning, consolidation, and decanning of the powders. Canning/decanning is expensive and raises the fabrication cost significantly above that of conventional, ingot metallurgy production methods. The cost differential can be offset by the superior performance of the RSP metallic alloys. However, without the performance database, it is difficult to convince potential users to adopt the RSP approach. Spray casting of the atomized molten droplets into suitable preforms for subsequent fabrication can be cost competitive with conventional processing. If the fine and stable microstructural features observed for the RSP approach are preserved during spray casing, a cost competitive product can be obtained that has superior properties and performance that cannot be obtained by conventional methods.

  2. Retinal Origin of Direction Selectivity in the Superior Colliculus

    Science.gov (United States)

    Shi, Xuefeng; Barchini, Jad; Ledesma, Hector Acaron; Koren, David; Jin, Yanjiao; Liu, Xiaorong; Wei, Wei; Cang, Jianhua

    2017-01-01

    Detecting visual features in the environment such as motion direction is crucial for survival. The circuit mechanisms that give rise to direction selectivity in a major visual center, the superior colliculus (SC), are entirely unknown. Here, we optogenetically isolate the retinal inputs that individual direction-selective SC neurons receive and find that they are already selective as a result of precisely converging inputs from similarly-tuned retinal ganglion cells. The direction selective retinal input is linearly amplified by the intracollicular circuits without changing its preferred direction or level of selectivity. Finally, using 2-photon calcium imaging, we show that SC direction selectivity is dramatically reduced in transgenic mice that have decreased retinal selectivity. Together, our studies demonstrate a retinal origin of direction selectivity in the SC, and reveal a central visual deficit as a consequence of altered feature selectivity in the retina. PMID:28192394

  3. Retinal origin of direction selectivity in the superior colliculus.

    Science.gov (United States)

    Shi, Xuefeng; Barchini, Jad; Ledesma, Hector Acaron; Koren, David; Jin, Yanjiao; Liu, Xiaorong; Wei, Wei; Cang, Jianhua

    2017-04-01

    Detecting visual features in the environment, such as motion direction, is crucial for survival. The circuit mechanisms that give rise to direction selectivity in a major visual center, the superior colliculus (SC), are entirely unknown. We optogenetically isolate the retinal inputs that individual direction-selective SC neurons receive and find that they are already selective as a result of precisely converging inputs from similarly tuned retinal ganglion cells. The direction-selective retinal input is linearly amplified by intracollicular circuits without changing its preferred direction or level of selectivity. Finally, using two-photon calcium imaging, we show that SC direction selectivity is dramatically reduced in transgenic mice that have decreased retinal selectivity. Together, our studies demonstrate a retinal origin of direction selectivity in the SC and reveal a central visual deficit as a consequence of altered feature selectivity in the retina.

  4. 支架植入术治疗上腔静脉综合征:金属支架的选择%Stent implantation for the treatment of superior vena cava syndrome:Selection of metallic stents

    Institute of Scientific and Technical Information of China (English)

    杨维竹; 潘恒; 黄兢姚; 江娜; 郑曲彬; 林俊清

    2013-01-01

    目的 探讨支架植入术治疗上腔静脉综合征(SVCS)中选择金属支架的要点.方法 收集51例SVCS,CT均显示上腔静脉(SVC)明显狭窄或闭塞;经股静脉穿刺插管,以球囊扩张狭窄或闭塞段后植入1枚或多枚金属内支架(Smart支架、Z-Stent支架、Fluency支架),直至复查造影显示SVC血流通畅.术后评价疗效.结果 51例SVCS中,50例双侧头臂静脉汇合处受累.支架植入术均获成功,28例植入Smart支架,17例植入Z-Stent,4例植入Fluency支架,2例为Smart支架内套Fluency支架;31例植入1枚支架,12例植入2枚支架,8例植入3枚支架.支架植入后48例临床症状明显改善,上腔静脉压显著下降.术中无SVC破裂等严重并发症发生.46例接受随访,其中18例于随访期内重现SVC阻塞症状,包括11例植入Smart支架、7例植入Z-Stent支架者,植入Fluency支架者未见复发.结论 根据SVC病变程度、位置,选择植入结构和特性适当的金属支架可使介入治疗SVCS安全、有效.%Objective To investigate the elective points of different types of metallic stents for implantation in patients with superior vena cava syndrome (SVCS).Methods Fifty-one patients with SVCS were enrolled.Enhanced CT showed obvious stenosis or occlusion of the superior vena cava (SVC) in all patients.Stent implantation was performed after balloon dilatation through femoral vein.One or more stents (Smart stent,Z-Stent and Fluency stent) were positioned till the obstruction of SVC flow was relieved.The therapeutic effects of stent implantation were evaluated.Results Among all 51 patients,invasion of bilateral brachiocephalic veins were observed in 50 patients.Technical success of stent implantation was achieved in all patients including 28 patients with Smart stent,17 with Z-Stent,4 with Fluency stent and 2 patients with Fluency+Smart stent.Significant improvements of SVCS symptoms was noticed in 48 patients after stent implantation,and the pressure of SVC

  5. Do institutional investors have superior stock selection ability in China?

    Institute of Scientific and Technical Information of China (English)

    Yihong; Deng; Yongxing; Xu

    2011-01-01

    This paper uses unique data on the shareholdings of both institutional and individual investors to directly investigate whether institutional investors have better stock selection ability than individual investors in China.Controlling for other factors,we find that institutional investors increase(decrease)their shareholdings in stocks that subsequently exhibit positive(negative)short-and long-term cumulative abnormal returns.In contrast individual investors decrease(increase)their shareholdings in stocks that subsequently exhibit positive(negative)short-and long-term cumulative abnormal returns.These findings indicate that institutional investors have superior stock selection ability in China.

  6. Percutaneous treatment of superior vena cava syndrome using metallic stents

    Energy Technology Data Exchange (ETDEWEB)

    De Gregorio Ariza, Miguel Angel; Gimeno, Maria Jose; Alfonso, Eduardo; Mainar, Antonio; Medrano, Joaquin; Lopez-Marin, Paloma [Department of Interventional Radiology, ' ' Lozano Blesa' ' University Hospital, Avda. San Juan Bosco 15, 50009 Zaragoza (Spain); Gamboa, Pablo [Division of Interventional Radiology, Ohio State University Hospital, Columbus, Ohio (United States); Tobio, Ricardo [Interventional Radiology, Clinica de la Zarzuela, Madrid (Spain); Herrera, Marcos [Division of Interventional Radiology, University of Minnesota, Minneapolis, Minnesota (United States)

    2003-04-01

    The purpose of this study was to evaluate the results of treatment of superior vena cava syndrome (SVCS) in patients with benign and malignant disease using expandable metallic stent. From January 1995 to April 2000, 87 expandable stents were implanted in 82 patients (59 men, 23 women; mean age 57.8 years, age range 39-79 years) for the treatment of SVCS. The SVCS was defined as symptomatic bilateral obstruction of venous drainage from head, neck and upper extremities. In 68 patients SVCS was due to malignant neoplasia, and in 14 cases it was due to benign aetiology. All patients were treated with expandable stent. We implanted 81 Wallstent prostheses and 6 Palmaz stents. Adjuvant thrombolysis was applied in 12 patients who required fibrinolysis. After recanalization, the stent was implanted in all cases in SVC (infra- or supra-azygos vein). All patients were treated with heparin of low molecular weight (HBPM) during 6 months. Patency was analyzed according to clinical symptoms and Doppler US or venograms exploration. Technical success was observed in all cases. Clinical success was reached in 78 of 82 patients (95.1%) (absence of symptoms in 2 or 3 days). Four patients suffered immediate thrombosis which required fibrinolitic treatment with a new prosthesis placement in 1 case. The follow-up for the malignant process was of 7.1 months (range 1-39 months) and in benign cases was 31.2 months (range 11-61 months). Sixty-two (91.1%) patients with malignancy died without SVCS symptomatology. All the patients with benign pathology are alive. Clinical primary patency in malignant cases was 87% with assisted patency of 96.2%. Endovascular therapy using metallic stent and thrombolysis is a successful method to treat SVCS due to benign or malignant aetiology. (orig.)

  7. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.

    2013-10-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them. © 2013 Published by Elsevier B.V.

  8. Orientational and directional selectivities of visual neurons in the superior colliculus of the cat

    Institute of Scientific and Technical Information of China (English)

    李兵; 王磊; 王毅; 刁云程

    1996-01-01

    Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.

  9. Sources of Heavy Metal Pollution into the St. Louis River, Lake Superior Watershed

    Science.gov (United States)

    Sternberg, S. P.; Palokangas, C.

    2013-12-01

    The St. Louis River begins in Hoyt Lakes, Minnesota and enters Lake Superior between Duluth, Minnesota and Superior, Wisconsin. The Partridge River and the Embarrass River are two of its main tributaries. National Pollutant Discharge Elimination System (NPDES) permits are issued for surface water dischargers under the Clean Water Act. The Permit Compliance System (PCS) and the Integrated Compliance Information System (ICIS) is a tool allowing public access to information contained in NPDES permits. Along the way to Lake Superior, 19 facilities list the St. Louis River, St. Louis Bay, part of the St. Louis River estuary, or one of its tributaries as a receiving water. Of these 19 locations, four report discharging heavy metals into the receiving water. Copper and Lead are the metals most frequently discharged.

  10. Metal selectivity determinants in a family of transition metal transporters.

    Science.gov (United States)

    Podar, Dorina; Scherer, Judith; Noordally, Zeenat; Herzyk, Pawel; Nies, Dietrich; Sanders, Dale

    2012-01-27

    Metal tolerance proteins (MTPs) are plant members of the cation diffusion facilitator (CDF) transporter family involved in cellular metal homeostasis. Members of the CDF family are ubiquitously found in all living entities and show principal selectivity for Zn(2+), Mn(2+), and Fe(2+). Little is known regarding metal selectivity determinants of CDFs. We identified a novel cereal member of CDFs in barley, termed HvMTP1, that localizes to the vacuolar membrane. Unlike its close relative AtMTP1, which is highly selective for Zn(2+), HvMTP1 exhibits selectivity for both Zn(2+) and Co(2+) as assessed by its ability to suppress yeast mutant phenotypes for both metals. Expression of HvMTP1/AtMTP1 chimeras in yeast revealed a five-residue sequence within the AtMTP1 N-segment of the His-rich intracytoplasmic loop that confines specificity to Zn(2+). Furthermore, mutants of AtMTP1 generated through random mutagenesis revealed residues embedded within transmembrane domain 3 that additionally specify the high degree of Zn(2+) selectivity. We propose that the His-rich loop, which might play a role as a zinc chaperone, determines the identity of the metal ions that are transported. The residues within transmembrane domain 3 can also influence metal selectivity, possibly through conformational changes induced at the cation transport site located within the membrane or at the cytoplasmic C-terminal domain.

  11. PILLARED CLAYS AS SUPERIOR CATALYSTS FOR SELECTIVE CATALYTIC REDUCTION OF NITRIC OXIDE

    Energy Technology Data Exchange (ETDEWEB)

    R.Q. Long; N. Tharappiwattananon; W.B. Li; R.T. Yang

    2000-09-01

    Removal of NO{sub x} (NO + NO{sub 2}) from exhaust gases is a challenging subject. V{sub 2}O{sub 5}-based catalysts are commercial catalysts for selective catalytic reduction (SCR) with NH{sub 3} for stationary sources. However, for diesel and lean-burn gasoline engines in vehicles, hydrocarbons would be the preferred reducing agents over NH{sub 3} because of the practical problems associated with the use of NH{sub 3} (i.e., handling and slippage through the reactor). The noble-metal three-way catalysts are not effective under these conditions. The first catalyst found to be active for selective catalytic reduction of NO by hydrocarbons in the presence of excess oxygen was copper exchanged ZSM-5 and other zeolites, reported in 1990 by Iwamoto in Japan and Held et al. in Germany. Although Cu-ZSM-5 is very active and the most intensively studied catalyst, it suffers from severe deactivation in engine tests, mainly due to H{sub 2}O and SO{sub 2}. In this project, we found that ion-exchanged pillared clays and MCM-41 catalysts showed superior SCR activities of NO with hydrocarbon. All Cu{sup 2+}-exchanged pillared clays showed higher SCR activities than Cu-ZSM-5 reported in the literature. In particular, H{sub 2}O and SO{sub 2} only slightly deactivated the SCR activity of Cu-TiO{sub 2}-PILC, whereas severe deactivation was observed for Cu-ZSM-5. Moreover, Pt/MCM-41 provided the highest specific NO reduction rates as compared with other Pt doped catalysts, i.e., Pt/Al{sub 2}O{sub 3}, Pt/SiO{sub 2} and Pt/ZSM-5. The Pt/MCM-41 catalyst also showed a good stability in the presence of H{sub 2}O and SO{sub 2}.

  12. Diet and prey selection by Lake Superior lake trout during springs 1986-2001

    Science.gov (United States)

    Ray, B.A.; Hrabik, T.R.; Ebener, M.P.; Gorman, O.T.; Schreiner, D.R.; Schram, S.T.; Sitar, S.P.; Mattes, W.P.; Bronte, C.R.

    2007-01-01

    We describe the diet and prey selectivity of lean (Salvelinus namaycush namaycush) and siscowet lake trout (S. n. siscowet) collected during spring (April–June) from Lake Superior during 1986–2001. We estimated prey selectivity by comparing prey numerical abundance estimates from spring bottom trawl surveys and lake trout diet information in similar areas from spring gill net surveys conducted annually in Lake Superior. Rainbow smelt (Osmerus mordax) was the most common prey and was positively selected by both lean and siscowet lake trout throughout the study. Selection by lean lake trout for coregonine (Coregonus spp.) prey increased after 1991 and corresponded with a slight decrease in selection for rainbow smelt. Siscowet positively selected for rainbow smelt after 1998, a change that was coincident with the decrease in selection for this prey item by lean lake trout. However, diet overlap between lean and siscowet lake trout was not strong and did not change significantly over the study period. Rainbow smelt remains an important prey species for lake trout in Lake Superior despite declines in abundance.

  13. No Superiority of Cemented Metal-on-Metal vs Metal-on-Polyethylene THA at 5-Year Follow-up

    NARCIS (Netherlands)

    Zijlstra, Wierd P.; Cheung, John; Sietsma, Maurits S.; van Raay, Jos J. A. M.; Deutman, Robert

    2009-01-01

    A randomized controlled trial was performed to compare the cemented Stanmore metal-on-metal (Biomet, Warsaw, Indiana) total hip arthroplasty (THA; 102 hips) to the cemented Stanmore metal-on-polyethylene (Biomet) THA (98 hips). The primary outcome was clinical performance. Radiological performance,

  14. Nanotubes within transition metal silicate hollow spheres: Facile preparation and superior lithium storage performances

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan; An, Yongling; Zhai, Wei; Gao, Xueping [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Feng, Jinkui, E-mail: jinkui@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Ci, Lijie [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Xiong, Shenglin [School of Materials Science and Engineering, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-10-15

    Highlights: • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were successfully prepared by a facile hydrothermal method using SiO{sub 2} nanosphere. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were tested as anode materials for lithium batteries. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} delivered superior electrochemical performance. • The lithium storage mechanism is probe via cyclic voltammetry and XPS. - Abstract: A series of transition metal silicate hollow spheres, including cobalt silicate (Co{sub 2}SiO{sub 4}), manganese silicate (MnSiO{sub 3}) and copper silicate (CuSiO{sub 3}.2H{sub 2}O, CuSiO{sub 3} as abbreviation in the text) were prepared via a simple and economic hydrothermal method by using silica spheres as chemical template. Time-dependent experiments confirmed that the resultants formed a novel type of hierarchical structure, hollow spheres assembled by numerous one-dimensional (1D) nanotubes building blocks. For the first time, the transition metal silicate hollow spheres were characterized as novel anode materials of Li-ion battery, which presented superior lithium storage capacities, cycle performance and rate performance. The 1D nanotubes assembly and hollow interior endow this kind of material facilitate fast lithium ion and electron transport and accommodate the big volume change during the conversion reactions. Our study shows that low-cost transition metal silicate with rationally designed nanostructures can be promising anode materials for high capacity lithium-ion battery.

  15. Uranium Metal Analysis via Selective Dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Sinkov, Sergey I.; Schmidt, Andrew J.; Chenault, Jeffrey W.

    2008-09-10

    Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation/corrosion in water. A thorough knowledge of the uranium metal concentration in sludge therefore is essential to successful sludge management and waste process design. The goal of this work was to establish a rapid routine analytical method to determine uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of up to 1000-fold higher total uranium concentrations (i.e., up to 30 wt% and more uranium) for samples to be taken during the upcoming sludge characterization campaign and in future analyses for sludge handling and processing. This report describes the experiments and results obtained in developing the selective dissolution technique to determine uranium metal concentration in K Basin sludge.

  16. Optimal selection of biochars for remediating metals ...

    Science.gov (United States)

    Approximately 500,000 abandoned mines across the U.S. pose a considerable, pervasive risk to human health and the environment due to possible exposure to the residuals of heavy metal extraction. Historically, a variety of chemical and biological methods have been used to reduce the bioavailability of the metals at mine sites. Biochar with its potential to complex and immobilize heavy metals, is an emerging alternative for reducing bioavailability. Furthermore, biochar has been reported to improve soil conditions for plant growth and can be used for promoting the establishment of a soil-stabilizing native plant community to reduce offsite movement of metal-laden waste materials. Because biochar properties depend upon feedstock selection, pyrolysis production conditions, and activation procedures used, they can be designed to meet specific remediation needs. As a result biochar with specific properties can be produced to correspond to specific soil remediation situations. However, techniques are needed to optimally match biochar characteristics with metals contaminated soils to effectively reduce metal bioavailability. Here we present experimental results used to develop a generalized method for evaluating the ability of biochar to reduce metals in mine spoil soil from an abandoned Cu and Zn mine. Thirty-eight biochars were produced from approximately 20 different feedstocks and produced via slow pyrolysis or gasification, and were allowed to react with a f

  17. Processing metallic glasses by selective laser melting

    Directory of Open Access Journals (Sweden)

    Simon Pauly

    2013-01-01

    Full Text Available Metallic glasses and their descendants, the so-called bulk metallic glasses (BMGs, can be regarded as frozen liquids with a high resistance to crystallization. The lack of a conventional structure turns them into a material exhibiting near-theoretical strength, low Young's modulus and large elasticity. These unique mechanical properties can be only obtained when the metallic melts are rapidly cooled to bypass the nucleation and growth of crystals. Most of the commonly known and used processing routes, such as casting, melt spinning or gas atomization, have intrinsic limitations regarding the complexity and dimensions of the geometries. Here, it is shown that selective laser melting (SLM, which is usually used to process conventional metallic alloys and polymers, can be applied to implement complex geometries and components from an Fe-base metallic glass. This approach is in principle viable for a large variety of metallic alloys and paves the way for the novel synthesis of materials and the development of parts with advanced functional and structural properties without limitations in size and intricacy.

  18. Continuous metal plasmonic frequency selective surfaces.

    Science.gov (United States)

    Zhang, Jianfa; Ou, Jun-Yu; Papasimakis, Nikitas; Chen, Yifang; Macdonald, Kevin F; Zheludev, Nikolay I

    2011-11-07

    In the microwave part of the spectrum, where losses are minimal, metal films regularly patterned (perforated) on the sub-wavelength scale achieve spectral selectivity by balancing the transmission and reflection characteristics of the surface. Here we show for optical frequencies, where joule losses are important, that periodic structuring of a metal film without violation of continuity (i.e. without perforation) is sufficient to achieve substantial modification of reflectivity. By engineering the geometry of the structure imposed on a surface one can dramatically change the perceived color of the metal without employing any form of chemical modification, thin-film coating or diffraction effects. This novel frequency selective effect is underpinned by plasmonic Joule losses in the constituent elements of the patterns (dubbed 'intaglio' and 'bas relief' metamaterials to distinguish indented and raised structures respectively) and is specific to the optical part of the spectrum. It has the advantage of maintaining the integrity of metal surfaces and is well suited to high-throughput fabrication via techniques such as nano-imprint.

  19. Selective Recovery of Metals from Geothermal Brines

    Energy Technology Data Exchange (ETDEWEB)

    Ventura, Susanna [SRI International, Menlo Park, CA (United States); Bhamidi, Srinivas [SRI International, Menlo Park, CA (United States); Hornbostel, Marc [SRI International, Menlo Park, CA (United States); Nagar, Anoop [SRI International, Menlo Park, CA (United States); Perea, Elisabeth [SRI International, Menlo Park, CA (United States)

    2016-12-16

    The objective of this project was to determine the feasibility of developing a new generation of highly selective low-cost ion-exchange resins based on metal-ion imprinted polymers for the separation of metals from geothermal fluids. Expansion of geothermal energy production over the entire U.S. will involve exploitation of low-to-medium temperature thermal waters. Creating value streams from the recovery of critical and near-critical metals from these thermal waters will encourage geothermal expansion. Selective extraction of metals from geothermal fluids is needed to design a cost-effective process for the recovery of lithium and manganese-two near-critical metals with well-known application in the growing lithium battery industry. We have prepared new lithium- and manganese-imprinted polymers in the form of beads by crosslinking polymerization of a metal polymerizable chelate, where the metal acts as a template. Upon leaching out the metal template, the crosslinked polymer is expected to leave cavities defined by the ligand functional group with enhanced selectivity for binding the template metal. We have demonstrated that lithium- and manganese-imprinted polymer beads can be used as selective solid sorbents for the extraction of lithium and manganese from brines. The polymers were tested both in batch extractions and packed bed lab-scale columns at temperatures of 45-100°C. Lithium-imprinted polymers were found to have Li+ adsorption capacity as high as 2.8 mg Li+/g polymer at 45°C. Manganese-imprinted polymers were found to have a Mn2+ adsorption capacity of more than 23 mg Mn2+/g polymer at 75°C. The Li+ extraction efficiency of the Li-imprinted polymer was found to be more that 95% when a brine containing 390 ppm Li+, 410 ppm Na+, and 390 ppm K+ was passed through a packed bed of the polymer in a lab-scale column at 45°C. In brines containing 360 ppm Li

  20. Active vacuum brazing of CNT films to metal substrates for superior electron field emission performance

    Science.gov (United States)

    Longtin, Rémi; Sanchez-Valencia, Juan Ramon; Shorubalko, Ivan; Furrer, Roman; Hack, Erwin; Elsener, Hansrudolf; Gröning, Oliver; Greenwood, Paul; Rupesinghe, Nalin; Teo, Kenneth; Leinenbach, Christian; Gröning, Pierangelo

    2015-02-01

    The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 °C with a Ag-Cu-Ti alloy and at 880 °C with a Cu-Sn-Ti-Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.35 Ω. The improved interfacial transport properties in the brazed films lead to superior electron field-emission properties when compared to the as-grown films. An emission current of 150 μA was drawn from the brazed nanotubes at an applied electric field of 0.6 V μm-1. The improvement in electron field-emission is mainly attributed to the reduction of the contact resistance between the nanotubes and the substrate. The joints have high re-melting temperatures up to the solidus temperatures of the alloys; far greater than what is achievable with standard solders, thus expanding the application potential of CNT films to high-current and high-power applications where substantial frictional or resistive heating is expected.

  1. Biosurfactant Mediated Biosynthesis of Selected Metallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Grażyna A. Płaza

    2014-08-01

    Full Text Available Developing a reliable experimental protocol for the synthesis of nanomaterials is one of the challenging topics in current nanotechnology particularly in the context of the recent drive to promote green technologies in their synthesis. The increasing need to develop clean, nontoxic and environmentally safe production processes for nanoparticles to reduce environmental impact, minimize waste and increase energy efficiency has become essential in this field. Consequently, recent studies on the use of microorganisms in the synthesis of selected nanoparticles are gaining increased interest as they represent an exciting area of research with considerable development potential. Microorganisms are known to be capable of synthesizing inorganic molecules that are deposited either intra- or extracellularly. This review presents a brief overview of current research on the use of biosurfactants in the biosynthesis of selected metallic nanoparticles and their potential importance.

  2. Superior selectivity and sensitivity of blue phosphorus nanotubes in gas sensing applications

    KAUST Repository

    Montes Muñoz, Enrique

    2017-05-23

    On the basis of first principles calculations, we study the adsorption of CO, CO2, NH3, NO, and NO2 molecules on armchair and zigzag blue phosphorus nanotubes. The nanotubes are found to surpass the gas sensing performance of other one-dimensional materials, in particular Si nanowires and carbon nanotubes, and two-dimensional materials, in particular graphene, phosphorene, and MoS2. Investigation of the energetics of the gas adsorption and induced charge transfers indicates that blue phosphorus nanotubes are highly sensitive to N-based molecules, in particular NO2, due to covalent bonding. The current–voltage characteristics of nanotubes connected to Au electrodes are derived by the non-equilibrium Green\\'s function formalism and used to quantitatively evaluate the change in resistivity upon gas adsorption. The observed selectivity and sensitivity properties make blue phosphorus nanotubes superior gas sensors for a wide range of applications.

  3. Selection of Superior Genotypes of Coffea Canephora Pierre on ControlledHybrid Population Using Cluster Analysis Method

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    Ucu Sumirat

    2007-05-01

    Full Text Available Selection of superior genotypes of robusta coffee (Coffea canephora to improve its important agronomic characters should be conducted continuously to get better planting productivity. The aim of this research was to select superior genotypes of Robusta coffee for high yield and high proportion of large bean. Selection was conducted on controlled hybrid populations, developed from three crossing parental clones, i.e. BP 961 x Q 121 (A, BP 409 x Q 121 (B and BP 961 x BP 409 (C. Selection was done by applying cluster analysis with complete linkage and Euclidean distance as the clustering method. The result of the research showed that the selection was successful to identify superior genotypes of Robusta coffee for high yield and high proportion of large bean. The parameters used (cherries weight/tree, bean weight/tree, bean size percentage > 6.5 mm and 100 cherries weight were effective in clustering the superior genotypes, indicated by increased minimum and average value of population. Yield potential and percentage of bean size > 6.5 mm of those genotypes were having better performance than the control genotype and its parent. The selection code A 95, B 28, B 62, B 66, B 74 and C 38 were considered  as promising superior genotypes of Robusta coffee, respectively. Key words: Coffea canephora, selection, bean size, yield, cluster analysis

  4. Identification of Some Walnut Genotypes in Lorestan Province of Iran and Selection of 54 Superior Genotypes

    Directory of Open Access Journals (Sweden)

    A. Mohammadi

    2015-06-01

    Full Text Available Identification and selection of superior genotypes is the first step in walnut breeding programs. For identifying superior genotypes in Lorestan province, Iran, 35000 seedling genotypes were evaluated during 2008-2009. 29 Phenological traits were evaluated using IPGIRI descriptors in 288 selected seedling genotypes. Finally 54 promising genotypes with 10 major phenological traits were evaluated and classified to five groups. Based on the results, The first group included B17 alone as a late leafing genotype. The second group included A11, J14, K20, H19, M13, J1, B14, E14, E6, G17, M7, O9, B7, L6, L10, F12, D6, J15, J16, N5 and N15 genotypes with high kernel percentage, very bright kernel colors, less shell thickness and medium basal fruit pore. M9 with the highest kernel percent among all of the genotypes and 80% of lateral bearing, closed basal fruit pore, less shell thickness and high fruit and kernel weight was classified in another groupe. A7, C5, N3, N18, A17, D1, N14, D4, I4, J6, K17, N4, N19, C10, E13, N13 and N16 genotypes with medium to high fruit diameter, less shell thickness, medium fruit and kernel weight and kernel percentage were classified in the next group. The fifth group included 10 promising genotypes consisting A1, A2, C12, D10, D11, D13, F3, D17, A3, N7, I13, J7, K9 and N11 with quite late leafing and lateral fruit bearing of more than 90% .

  5. MERCURY IN METAL ORE DEPOSITS: AN UNRECOGNIZED, WIDESPREAD SOURCE TO LAKE SUPERIOR SEDIMENTS, CONTRIBUTION #1072

    Science.gov (United States)

    Mining operations have worked the rich mineral resources of the Lake Superior Basin for over 150 years, leaving industrially impacted regions with tailing piles and smelters. In Lake Superior sediments, mercury and copper inventories increase towards shorelines and are highly cor...

  6. MERCURY IN METAL ORE DEPOSITS: AN UNRECOGNIZED, WIDESPREAD SOURCE TO LAKE SUPERIOR SEDIMENTS, CONTRIBUTION #1072

    Science.gov (United States)

    Mining operations have worked the rich mineral resources of the Lake Superior Basin for over 150 years, leaving industrially impacted regions with tailing piles and smelters. In Lake Superior sediments, mercury and copper inventories increase towards shorelines and are highly cor...

  7. Genome-wide selection of superior reference genes for expression studies in Ganoderma lucidum.

    Science.gov (United States)

    Xu, Zhichao; Xu, Jiang; Ji, Aijia; Zhu, Yingjie; Zhang, Xin; Hu, Yuanlei; Song, Jingyuan; Chen, Shilin

    2015-12-15

    Quantitative real-time polymerase chain reaction (qRT-PCR) is widely used for the accurate analysis of gene expression. However, high homology among gene families might result in unsuitability of reference genes, which leads to the inaccuracy of qRT-PCR analysis. The release of the Ganoderma lucidum genome has triggered numerous studies to be done on the homology among gene families with the purpose of selecting reliable reference genes. Based on the G. lucdum genome and transcriptome database, 38 candidate reference genes including 28 novel genes were systematically selected and evaluated for qRT-PCR normalization. The result indicated that commonly used polyubiquitin (PUB), beta-actin (BAT), and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were unsuitable reference genes because of the high sequence similarity and low primer specificity. According to the evaluation of RefFinder, cyclophilin 5 (CYP5) was ranked as the most stable reference gene for 27 tested samples under all experimental conditions and eighteen mycelial samples. Based on sequence analysis and expression analysis, our study suggested that gene characteristic, primer specificity of high homologous genes, allele-specificity expression of candidate genes and under-evaluation of reference genes influenced the accuracy and sensitivity of qRT-PCR analysis. This investigation not only revealed potential factors influencing the unsuitability of reference genes but also selected the superior reference genes from more candidate genes and testing samples than those used in the previous study. Furthermore, our study established a model for reference gene analysis by using the genomic sequence.

  8. Serum Lipids and Lipoproteins Levels and Selected Trace Metals In ...

    African Journals Online (AJOL)

    Serum Lipids and Lipoproteins Levels and Selected Trace Metals In Newly ... This study aim to determine the serum levels of trace metals and correlate same with serum levels of lipoproteins (an established marker of HBP) in ... Article Metrics.

  9. Synthesis of agarose-metal/semiconductor nanoparticles having superior bacteriocidal activity and their simple conversion to metal-carbon composites

    Indian Academy of Sciences (India)

    K K R Datta; B Srinivasan; H Balaram; M Eswaramoorthy

    2008-11-01

    Agarose, a naturally occurring biopolymer is used for the stabilization of metal, semiconductor nanoparticles. Ag and Cu nanoparticles stabilized in agarose matrix show excellent antibacterial activity against E. coli bacteria. The well dispersed metal nanoparticles within the agarose composite films can be readily converted to carbon-metal composites of catalytic importance.

  10. Methods of selectively incorporating metals onto substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ernst; Richard D. (Salt Lake City, UT), Eyring; Edward M. (Salt Lake City, UT), Turpin; Gregory C. (Salt Lake City, UT), Dunn; Brian C. (Salt Lake City, UT)

    2008-09-30

    A method for forming multi-metallic sites on a substrate is disclosed and described. A substrate including active groups such as hydroxyl can be reacted with a pretarget metal complex. The target metal attached to the active group can then be reacted with a secondary metal complex such that an oxidation-reduction (redox) reaction occurs to form a multi-metallic species. The substrate can be a highly porous material such as aerogels, xerogels, zeolites, and similar materials. Additional metal complexes can be reacted to increase catalyst loading or control co-catalyst content. The resulting compounds can be oxidized to form oxides or reduced to form metals in the ground state which are suitable for practical use.

  11. Designer ligands: The search for metal ion selectivity

    Directory of Open Access Journals (Sweden)

    Perry T. Kaye

    2011-03-01

    Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

  12. Superior Stable and Long Life Sodium Metal Anodes Achieved by Atomic Layer Deposition.

    Science.gov (United States)

    Zhao, Yang; Goncharova, Lyudmila V; Lushington, Andrew; Sun, Qian; Yadegari, Hossein; Wang, Biqiong; Xiao, Wei; Li, Ruying; Sun, Xueliang

    2017-03-03

    Na-metal batteries are considered as the promising alternative candidate for Li-ion battery beneficial from the wide availability and low cost of sodium, high theoretical specific capacity, and high energy density based on the plating/stripping processes and lowest electrochemical potential. For Na-metal batteries, the crucial problem on metallic Na is one of the biggest challenges. Mossy or dendritic growth of Na occurs in the repetitive Na stripping/plating process with an unstable solid electrolyte interphase layer of nonuniform ionic flux, which can not only lead to the low Coulombic efficiency, but also can create short circuit risks, resulting in possible burning or explosion. In this communication, the atomic layer deposition of Al2 O3 coating is first demonstrated for the protection of metallic Na anode for Na-metal batteries. By protecting Na foil with ultrathin Al2 O3 layer, the dendrites and mossy Na formation have been effectively suppressed and lifetime has been significantly improved. Furthermore, the thickness of protective layer has been further optimized with 25 cycles of Al2 O3 layer presenting the best performance over 500 cycles. The novel design of atomic layer deposition protected metal Na anode may bring in new opportunities to the realization of the next-generation high energy-density Na metal batteries.

  13. ALFIN-ORG: Sitio web para el desarrollo de habilidades informacionales en el Instituto Superior Metalúrgico de Moa

    Directory of Open Access Journals (Sweden)

    MSc. Miguel Ángel Fernández Marín

    2016-04-01

    Full Text Available En el Instituto Superior Minero Metalúrgico de Moa, no existe acceso pleno a todas las fuentes de información, no se le da el uso adecuado a las tecnologías, no hay cultura infor­macional de cómo aprovecharla y a la hora de determinar que es útil, no se toma la decisión correcta. Debido a esto, existe un cúmulo de información que no es aprovechada y tras el avance tecnológico crece cada día. Por estas ra­zones, es necesario que se pueda trabajar y asimilar toda la información de manera correcta, basado en el desarro­llo de estrategias de búsqueda mediante la utilización de los medios digitales. Para darle solución a la problemática anterior, se proyecta el objetivo de crear un sitio web que contribuya al desarrollo de habilidades informacionales en el Instituto Superior Minero Metalúrgico de Moa. Para la con­fección del sitio web se utilizó Hot Potatoes 6.3.0.3 para di­señar los sistemas de ejercicios de autoevaluación en el sitio web. Joomla 1.6.0 para el desarrollo del sitio web. Como len­guaje de programación PHP Script Language versión 5.2.6. Como gestor de Bases de Datos MySQL Database versión 5.0.51b. El resultado del trabajo constituye un sitio web que posee una estructura informativa-evaluativa para lograr las habilidades informacionales en el Instituto Superior Minero Metalúrgico de Moa.

  14. PREPARATION OF A POLYMER ARTICLE FOR SELECTIVE METALLIZATION

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention relates to the field of selective metallization, and in particular to preparing a polymer article for selective metallization by submerging the article in a first liquid, and while submergedirradiate the article by a laser beam the area of the article on which the metal...... is to be deposited. An activation step, prior to the selective metallization, comprises submerging the article in an activation liquid for depositing seedparticles in the selected area. The irradiation of the selected area is proportionate so as to cause a temporary meltingof the polymer in the surface...... of the selected area of the polymer article. The invention is advantageous in that the preparation may be performed with a relatively high scan rate across the polymer article, and in that a quite limited use of toxic chemicals....

  15. PREPARATION OF A POLYMER ARTICLE FOR SELECTIVE METALLIZATION

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention relates to the field of selective metallization, and in particular to preparing a polymer article for selective metallization by submerging the article in a first liquid, and while submergedirradiate the article by a laser beam the area of the article on which the metal...... is to be deposited. An activation step, prior to the selective metallization, comprises submerging the article in an activation liquid for depositing seedparticles in the selected area. The irradiation of the selected area is proportionate so as to cause a temporary meltingof the polymer in the surface...... of the selected area of the polymer article. The invention is advantageous in that the preparation may be performed with a relatively high scan rate across the polymer article, and in that a quite limited use of toxic chemicals....

  16. Metallic Nickel Hydroxide Nanosheets Give Superior Electrocatalytic Oxidation of Urea for Fuel Cells.

    Science.gov (United States)

    Zhu, Xiaojiao; Dou, Xinyu; Dai, Jun; An, Xingda; Guo, Yuqiao; Zhang, Lidong; Tao, Shi; Zhao, Jiyin; Chu, Wangsheng; Zeng, Xiao Cheng; Wu, Changzheng; Xie, Yi

    2016-09-26

    The direct urea fuel cell (DUFC) is an important but challenging renewable energy production technology, it offers great promise for energy-sustainable developments and mitigating water contamination. However, DUFCs still suffer from the sluggish kinetics of the urea oxidation reaction (UOR) owing to a 6 e(-) transfer process, which poses a severe hindrance to their practical use. Herein, taking β-Ni(OH)2 nanosheets as the proof-of-concept study, we demonstrated a surface-chemistry strategy to achieve metallic Ni(OH)2 nanosheets by engineering their electronic structure, representing a first metallic configuration of transition-metal hydroxides. Surface sulfur incorporation successfully brings synergetic effects of more exposed active sites, good wetting behavior, and effective electron transport, giving rise to greatly enhanced performance for UOR. Metallic nanosheets exhibited a much higher current density, smaller onset potential and stronger durability.

  17. Metalloregulatory proteins: metal selectivity and allosteric switching.

    Science.gov (United States)

    Reyes-Caballero, Hermes; Campanello, Gregory C; Giedroc, David P

    2011-07-01

    Prokaryotic organisms have evolved the capacity to quickly adapt to a changing and challenging microenvironment in which the availability of both biologically required and non-essential transition metal ions can vary dramatically. In all bacteria, a panel of metalloregulatory proteins controls the expression of genes encoding membrane transporters and metal trafficking proteins that collectively manage metal homeostasis and resistance. These "metal sensors" are specialized allosteric proteins, in which the direct binding of a specific or small number of "cognate" metal ion(s) drives a conformational change in the regulator that allosterically activates or inhibits operator DNA binding, or alternatively, distorts the promoter structure thereby converting a poor promoter to a strong one. In this review, we discuss our current understanding of the features that control metal specificity of the allosteric response in these systems, and the role that structure, thermodynamics and conformational dynamics play in mediating allosteric activation or inhibition of DNA binding. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Selective precipitation of heavy metals as controlled by a sulfide-selective electrode

    NARCIS (Netherlands)

    Veeken, A.H.M.; Vries, S.; Mark, van der A.

    2003-01-01

    Sulfide precipitation is superior to hydroxide precipitation for removal of heavy metals from wastewaters as it results in lower effluent concentrations and less interference from chelating agents. However, sulfide precipitation is not widely applied in practice because the dosing of sulfide cannot

  19. Structural elements of metal selectivity in metal sensor proteins.

    Science.gov (United States)

    Pennella, Mario A; Shokes, Jacob E; Cosper, Nathaniel J; Scott, Robert A; Giedroc, David P

    2003-04-01

    Staphylococcus aureus CzrA and Mycobacterium tuberculosis NmtR are homologous zinccobalt-responsive and nickelcobalt-responsive transcriptional repressors in vivo, respectively, and members of the ArsRSmtB superfamily of prokaryotic metal sensor proteins. We show here that Zn(II) is the most potent negative allosteric regulator of czr operatorpromoter binding in vitro with the trend Zn(II)>Co(II)Ni(II), whereas the opposite holds for the binding of NmtR to the nmt operatorpromoter, Ni(II)>Co(II)>Zn(II). Characterization of the metal coordination complexes of CzrA and NmtR by UVvisible and x-ray absorption spectroscopies reveals that metals that form four-coordinate tetrahedral complexes with CzrA [Zn(II) and Co(II)] are potent regulators of DNA binding, whereas metals that form five- or six-coordinate complexes with NmtR [Ni(II) and Co(II)] are the strongest allosteric regulators in this system. Strikingly, the Zn(II) coordination complexes of CzrA and NmtR cannot be distinguished from one another by x-ray absorption spectroscopy, with the best fit a His-3-carboxylate complex in both cases. Inspection of the primary structures of CzrA and NmtR, coupled with previous functional data, suggests that three conserved His and one Asp from the C-terminal alpha5 helix donate ligands to create a four-coordinate complex in both CzrA and NmtR, with NmtR uniquely capable of expanding its coordination number in the Ni(II) and Co(II) complexes by recruiting additional His ligands from a C-terminal extension of the alpha5 helix.

  20. Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

    Directory of Open Access Journals (Sweden)

    Marsha C. Kanan

    2009-10-01

    Full Text Available A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO based sensors for the selective and sensitive detection of various environmental pollutants is presented.

  1. Energy use in selected metal casting facilities - 2003

    Energy Technology Data Exchange (ETDEWEB)

    Eppich, Robert E. [Eppich Technologies, Syracuse, IN (United States)

    2004-05-01

    This report represents an energy benchmark for various metal casting processes. It describes process flows and energy use by fuel type and processes for selected casting operations. It also provides recommendations for improving energy efficiency in casting.

  2. Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation.

    Science.gov (United States)

    Bumajdad, Ali; Madkour, Metwally

    2014-04-28

    Although TiO2 is one of the most efficient photocatalysts, with the highest stability and the lowest cost, there are drawbacks that hinder its practical applications like its wide band gap and high recombination rate of the charge carriers. Consequently, many efforts were directed toward enhancing the photocatalytic activity of TiO2 and extending its response to the visible region. To head off these attempts, modification of TiO2 with noble metal nanoparticles (NMNPs) received considerable attention due to their role in accelerating the transfer of photoexcited electrons from TiO2 and also due to the surface plasmon resonance which induces the photocatalytic activity of TiO2 under visible light irradiation. This insightful perspective is devoted to the vital role of TiO2 photocatalysis and its drawbacks that urged researchers to find solutions such as modification with NMNPs. In a coherent context, we discussed here the characteristics which qualify NMNPs to possess a great enhancement effect for TiO2 photocatalysis. Also we tried to understand the reasons behind this effect by means of photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra, and Density Functional Theory (DFT) calculations. Then the mechanism of action of NMNPs upon deposition on TiO2 is presented. Finally we introduced a survey of the behaviour of these noble metal NPs on TiO2 based on the particle size and the loading amount.

  3. Modulation by Amino Acids: Toward Superior Control in the Synthesis of Zirconium Metal-Organic Frameworks.

    Science.gov (United States)

    Gutov, Oleksii V; Molina, Sonia; Escudero-Adán, Eduardo C; Shafir, Alexandr

    2016-09-12

    The synthesis of zirconium metal-organic frameworks (Zr MOFs) modulated by various amino acids, including l-proline, glycine, and l-phenylalanine, is shown to be a straightforward approach toward functional-group incorporation and particle-size control. High yields in Zr-MOF synthesis are achieved by employing 5 equivalents of the modulator at 120 °C. At lower temperatures, the method provides a series of Zr MOFs with increased particle size, including many suitable for single-crystal X-ray diffraction studies. Furthermore, amino acid modulators can be incorporated at defect sites in Zr MOFs with an amino acid/ligand ratio of up to 1:1, depending on the ligand structure and reaction conditions. The MOFs obtained through amino acid modulation exhibit an improved CO2 -capture capacity relative to nonfunctionalized materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Selective metallization by seeded growth on patterned gold nanoparticle arrays

    NARCIS (Netherlands)

    Raza, M.A.; Zandvliet, H.J.W.; Poelsema, B.; Kooij, E.S.

    2013-01-01

    We describe the selective metallization by electroless gold deposition on pre-patterned arrays of seed particles. In the first step, highly selective deposition of seeds (gold nanoparticles) on silicon oxide surfaces is achieved using pure water. In the second step, employing an electroless seeded g

  5. Selective metallization of alumina by laser

    NARCIS (Netherlands)

    Shrivastva, P.B.; Boose, C.A.; Kolster, B.H.; Harteveld, C.; Meinders, B.

    1991-01-01

    Nickel has been selectively deposited on an alumina substrate without any pretreatment from a flow of a nickel acetate solution using the focused beam of an excimer laser. Nickel spots as well as nickel lines were drawn and subsequently plated with an electroless Ni-B coating. Excellent adhesion of

  6. Metal-organic frameworks as selectivity regulators for hydrogenation reactions

    Science.gov (United States)

    Zhao, Meiting; Yuan, Kuo; Wang, Yun; Li, Guodong; Guo, Jun; Gu, Lin; Hu, Wenping; Zhao, Huijun; Tang, Zhiyong

    2016-11-01

    Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe3+, Cr3+ or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design

  7. The Analysis Of Simple Additive Weighting With Topsis Method To Selection Superior Seed Of Sugar Cane

    Directory of Open Access Journals (Sweden)

    Heri Gunawan

    2016-02-01

    Full Text Available According to the results of observations on the PTP (Persero Nusantara II Kwala Madu Gardens sugarcane production is increasing but the results are not optimal, so that the determination of superior seed cane is apt to be one of the factors supporting the development of sugar cane production.Determining the appropriate sugarcane seedlings to the conditions as criteria: climate, rainfall, soil acidity (pH, soil type, drainage (water systems based on the type of sugarcane cultivated is still a classic problem. In this study, using a 4 (four alternative seed is PS58, BM13579, BZ134 and Kidang Kencana. In this research, the analysis by applying TOPSIS and SAW method to determine sugarcane seeds. Whether the results of the analysis can give the decision to determine the seeds of sugarcane using SAW and TOPSIS. From the analysis of the decision obtained as follows: From the rank of distance closeness to the ideal solution TOPSIS process can be generated as follows. For V1 (alternative 1: PS58 = 0.1836, V2 (alternative 2: BM 13579 = 0.7309, V3 (alternative 3: BZ134 = 0.8082, and V4 (alternative 4: Kidang Kecana. Then it can be decided which is the third alternative seed is BZ134.

  8. Alkali-Metal-Ion-Functionalized Graphene Oxide as a Superior Anode Material for Sodium-Ion Batteries.

    Science.gov (United States)

    Wan, Fang; Li, Yu-Han; Liu, Dai-Huo; Guo, Jin-Zhi; Sun, Hai-Zhu; Zhang, Jing-Ping; Wu, Xing-Long

    2016-06-06

    Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions.

  9. Fatigue Characteristics of Selected Light Metal Alloys

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2016-03-01

    Full Text Available The paper addresses results of fatigue testing of light metal alloys used in the automotive as well as aerospace and aviation industries, among others. The material subject to testing comprised hot-worked rods made of the AZ31 alloy, the Ti-6Al-4V two-phase titanium alloy and the 2017A (T451 aluminium alloy. Both low- and high-cycle fatigue tests were conducted at room temperature on the cycle asymmetry ratio of R=-1. The low-cycle fatigue tests were performed using the MTS-810 machine on two levels of total strain, i.e.Δεc= 1.0% and 1.2%. The high-cycle fatigue tests, on the other hand, were performed using a machine from VEB Werkstoffprufmaschinen-Leipzig under conditions of rotary bending. Based on the results thus obtained, one could develop fatigue life characteristics of the materials examined (expressed as the number of cycles until failure of sample Nf as well as characteristics of cyclic material strain σa=f(N under the conditions of low-cycle fatigue testing. The Ti-6Al-4V titanium alloy was found to be characterised by the highest value of fatigue life Nf, both in lowand high-cycle tests. The lowest fatigue life, on the other hand, was established for the aluminium alloys examined. Under the high-cycle fatigue tests, the life of the 2017A aluminium and the AZ31 magnesium alloy studied was determined by the value of stress amplitude σa. With the stress exceeding 150 MPa, it was the aluminium alloy which displayed higher fatigue life, whereas the magnesium alloy proved better on lower stress.

  10. Accumulation of heavy metals in selected medicinal plants.

    Science.gov (United States)

    Sarma, Hemen; Deka, Suresh; Deka, Hemen; Saikia, Rashmi Rekha

    2011-01-01

    In this review, we evaluate the reports published between 1993 and 2011 that address the heavy metal accumulation in 88 medicinal plant species. We compare the safe limits for heavy metals set by governmental agencies vs. the levels at which such metals actually exist in selected medicinal plants. We also evaluate the uses and effectiveness of medicinal plants in health care, and assess the hazards of medicinal plant uses, in view of the growing worldwide use of medicinal plants. From our extensive review of the literature, we discovered that a maximum permissible level (MPL) of Pb is exceeded in 21 plant medicine species, Cd in 44 species, and Hg in 10 species. Vetiveria zizanioides a potential candidate species for the treatment of cardiovascular diseases absorb a wide range of heavy metals from metal-contaminated soils. We believe that this species is the single most impressive example of a potentially hazardous medicinal plant. Based on our review, we endorse the hypothesis that heavy metal accumulation by medicinal plants is mainly caused by extraction of soluble metals from contaminated soil, sediments and air. One continuing problem in protecting consumers of plant-based medicines is that permissible levels of all heavy metals in herbal medicine have not yet been standardized by regulating governmental entities. Moreover, there are few limit tests that exist for heavy metal content of medicinal plants, or permissible limits for essential dietary minerals, in most medicinal plants. The dearth of such limits hamstrings development of medicinal plant research and delays the release of either new or improved versions of medicinal plants or their components. In the present review, we emphasize that medicinal plants are often subjected to heavy metal contamination and that the levels at which these heavy metals sometimes occur exceeds permissible levels for some species. Therefore, collecting medicinal plants from areas that are, or may be, contaminated should be

  11. Selection of Superior Strains of Cordyceps militaris with Enhanced Fruiting Body Productivity

    Science.gov (United States)

    Park, Young-Jin; Lee, Je-O; Han, Sang-Kuk; Lee, Won-Ho; Choi, Sung-Keun; Shrestha, Bhushan

    2006-01-01

    In vitro fruiting bodies were produced from ten different isolates of Cordyceps militaris EFCC C-5736, EFCC C-5941, EFCC C-5976, EFCC C-6040, EFCC C-6849, EFCC C-7268, EFCC C-7342, EFCC C-7992, EFCC C-8027 and EFCC C-8549. Single ascospores were isolated from in vitro grown fruiting bodies and used for fruiting body production in brown rice medium by both intra-strain crossing and out-crossing. Length and dry wt. of stromata grown in vitro were measured. Strains producing highest dry wt. of stromata were selected. Both intra-strain crossings and inter-strain crossings of single ascospore strains were found to produce profuse fruiting bodies of C. militaris. PMID:24039486

  12. fMR-adaptation indicates selectivity to audiovisual content congruency in distributed clusters in human superior temporal cortex

    Directory of Open Access Journals (Sweden)

    Blomert Leo

    2010-02-01

    Full Text Available Abstract Background Efficient multisensory integration is of vital importance for adequate interaction with the environment. In addition to basic binding cues like temporal and spatial coherence, meaningful multisensory information is also bound together by content-based associations. Many functional Magnetic Resonance Imaging (fMRI studies propose the (posterior superior temporal cortex (STC as the key structure for integrating meaningful multisensory information. However, a still unanswered question is how superior temporal cortex encodes content-based associations, especially in light of inconsistent results from studies comparing brain activation to semantically matching (congruent versus nonmatching (incongruent multisensory inputs. Here, we used fMR-adaptation (fMR-A in order to circumvent potential problems with standard fMRI approaches, including spatial averaging and amplitude saturation confounds. We presented repetitions of audiovisual stimuli (letter-speech sound pairs and manipulated the associative relation between the auditory and visual inputs (congruent/incongruent pairs. We predicted that if multisensory neuronal populations exist in STC and encode audiovisual content relatedness, adaptation should be affected by the manipulated audiovisual relation. Results The results revealed an occipital-temporal network that adapted independently of the audiovisual relation. Interestingly, several smaller clusters distributed over superior temporal cortex within that network, adapted stronger to congruent than to incongruent audiovisual repetitions, indicating sensitivity to content congruency. Conclusions These results suggest that the revealed clusters contain multisensory neuronal populations that encode content relatedness by selectively responding to congruent audiovisual inputs, since unisensory neuronal populations are assumed to be insensitive to the audiovisual relation. These findings extend our previously revealed mechanism for

  13. PILLARED CLAYS AS SUPERIOR CATALYSTS FOR SELECTIVE CATALYTIC REDUCTION OF NITRIC OXIDE

    Energy Technology Data Exchange (ETDEWEB)

    R. Q. LONG; R.T. YANG

    1998-09-30

    Selective catalytic reduction (SCR) of NO{sub x} by hydrocarbons was investigated on Pt doped MCM-41 and copper ion and/or cerium ion-exchanged Al-MCM-41 in the presence of excess oxygen. It was found that Pt/MCM-41 provided the highest specific NO reduction rates as compared with other Pt doped catalysts reported in the literature, such as Pt/Al{sub 2}O{sub 3} and Pt/ZSM-5. For different hydrocarbons, the catalytic activity decreased according to the sequence of C{sub 3}H{sub 6} {approx} C{sub 2}H{sub 4} >> C{sub 3}H{sub 8} > CH{sub 4}. This catalyst was also stable in the presence of H{sub 2}O and SO{sub 2}. Cu exchanged Al-MCM-41 and cerium promoted Cu-Al-MCM-41 (i.e., Ce-Cu-Al-MCM-41) were also found to be active in this reaction. Higher NO{sub x} conversions to N2 were obtained on the Ce-Cu-Al-MCM-41 as compared with Cu-Al-MCM-41. The activity of Ce-Cu-Al-MCM-41 was approximately the same as that of Cu-ZSM-5; but the former had a wider temperature window. TPR results indicated that only isolated Cu{sup 2+} and Cu{sup +} ions were detected in the Cu{sup 2+}-exchanged Al-MCM-41 samples, which may play an important role in the selective catalytic reduction of NO{sub x} to N{sub 2}. After some cerium ions were introduced into Cu-Al-MCM-41, Cu{sup 2+} in the molecular sieve became more easily reducible by H{sub 2}. This may be related to the increase of catalytic activity of NO{sub x} reduction by ethylene.

  14. Selection of ectomycorrhizal willow genotype in phytoextraction of heavy metals.

    Science.gov (United States)

    Hrynkiewicz, Katarzyna; Baum, Christel

    2013-01-01

    Willow clones are used for the phytoextraction of heavy metals from contaminated soils and are usually mycorrhizal. The receptiveness of willow clones for mycorrhizal inoculum varies specific to genotype; however, it is unknown if this might have a significant impact on their efficiency in phytoextraction of heavy metals. Therefore, a model system with mycorrhizal and non-mycorrhizal willows of two different genotypes--one with usually stronger natural mycorrhizal colonization (Salix dasyclados), and one with lower natural mycorrhizal colonization (S. viminalis)--was investigated for its efficiency of phytoextraction of heavy metals (Cd, Pb, Cu, Zn) from contaminated soil. Inoculation with the ectomycorrhizal fungus Amanita muscaria significantly decreased the biomass of leaves of both inoculated willow clones, and increased or had no effect on the biomass of trunks and roots of S. dasyclados and S. viminalis, respectively. The concentrations of heavy metals in the biomass of S. dasyclados were in general higher than in S. viminalis irrespective of inoculation with the ectomycorrhizal fungus. Inoculation with A. muscaria significantly decreased the concentration of Cu in the trunks of both Salix taxa, but did not affected the concentrations of other heavy metals in the biomass. In conclusion, stronger receptiveness of willow clones for mycorrhizal inoculum was correlated with an increased total extraction of heavy metals from contaminated soils. Therefore, this seems to be a suitable criterion for effective willow clone selection for phytoremediation. Increased biomass production with relatively constant metal concentrations seems to be a major advantage of mycorrhizal formation of willows in phytoremediation of contaminated soils.

  15. KNOWLEDGE ENGINEERING TO AID THE RECRUITMENT PROCESS OF AN INDUSTRY BY IDENTIFYING SUPERIOR SELECTION CRITERIA

    Directory of Open Access Journals (Sweden)

    N. Sivaram

    2011-01-01

    Full Text Available Recruitment of the most appropriate employees and their retention are the immense challenges for the HR department of most of the industries. Every year IT companies recruit fresh graduates through their campus selection programs. Usually industries examine the skills of the candidate by conducting tests, group discussion and number of interviews. This process requires enormous amount of effort and investment. During each phase of the recruitment process, candidates are filtered based on some performance criteria. The problem domain is complex and the aspects of candidates that impact the recruitment process is not explicit. The intelligence of the recruitment process is spread among the domain experts and extracted through knowledge acquisition techniques. This research focuses on investigating the underlying criteria and tries to capitalize on the existing patterns, to minimize the effort made during the recruitment process. The approach here is to provide the insights through in-depth empirical characterization and evaluation of decision trees for the recruitment problem domain. Experiments were conducted with the data collected from an IT industry to support their hiring decisions. Pruned and unpruned trees were constructed using ID3, C4.5 and CART algorithms. It was observed that the performance of the C4.5 algorithm is high. The recruitment process differs for each industry based on the nature of the projects carried out. Experiments were conducted to determine the attributes that best fits the problem domain. Using the constructed decision trees discussions were made with the domain experts to deduce viable decision rules.

  16. Selection for superior growth advances the onset of puberty and increases reproductive performance in ewe lambs.

    Science.gov (United States)

    Rosales Nieto, C A; Ferguson, M B; Macleay, C A; Briegel, J R; Martin, G B; Thompson, A N

    2013-06-01

    The reproductive efficiency of the entire sheep flock could be improved if ewe lambs go through puberty early and produce their first lamb at 1 year of age. The onset of puberty is linked to the attainment of critical body mass, and therefore we tested whether it would be influenced by genetic selection for growth rate or for rate of accumulation of muscle or fat. We studied 136 Merino ewe lambs with phenotypic values for depth of eye muscle (EMD) and fat (FAT) and Australian Sheep Breeding Values at post-weaning age (200 days) for live weight (PWT), eye muscle depth (PEMD) and fat depth (PFAT). First oestrus was detected with testosterone-treated wethers and then entire rams as the ewes progressed from 6 to 10 months of age. Blood concentrations of leptin and IGF-I were measured to test whether they were related to production traits and reproductive performance (puberty, fertility and reproductive rate). In total, 97% of the lambs reached first oestrus at average weight 39.4 ± 0.4 kg (mean ± s.e.m.) and age 219 days (range 163 to 301). Age at first oestrus decreased with increases in values for PWT (P growth can accelerate the onset of puberty and increase fertility and reproductive rate of Merino ewe lambs. The metabolic hormones, IGF-I and leptin, might act as a physiological link between the growing tissues and the reproductive axis.

  17. Metal selective co-ordinative self-assembly of -donors

    Indian Academy of Sciences (India)

    Ankit Jain; K Venkata Rao; Ankita Goswami; Subi J George

    2011-11-01

    Metal selective co-ordinative nanostructures were constructed by the supramolecular co-assembly of pyridine appended TTF (TTF-Py) and pyrene (PYR-Py) derivatives in appropriate solvent composition mixtures with metal ions.Microscopic analyses show that TTF-Py shows distinctive morphology with either of these metal ions, forming I-D tapes with 1:1 Pb2+ complex and 2-D sheets with 1:2 Zn2+ complex. A rationale has been provided from molecular level packing for such hierarchical changes. In case of Cu2+, we have observed an anomalous binding of metal ion to the core sulphur groups causing redox changes in the TTF core. PYR-Py on the other hand is shown to be a fluorescent sensor for Pb2+, Zn2+, Hg2+ and Ag+. With different fluorescent response for metal complexes, we essentially obtained similar 1-D assemblies suggesting similar binding modes for all of them. Supramolecular approach through which morphology of an electron donor moiety can be engineered by metal ions can be a new tool in nanoelectronics.

  18. Tissue specific metal characterization of selected fish species in Pakistan.

    Science.gov (United States)

    Ahmed, Mukhtiar; Ahmad, Taufiq; Liaquat, Muhammad; Abbasi, Kashif Sarfraz; Farid, Ibrahim Bayoumi Abdel; Jahangir, Muhammad

    2016-04-01

    Concentration of various metals, i.e., zinc (Zn), copper (Cu), lead (Pb), nickel (Ni), iron (Fe), manganese (Mn), chromium (Cr), and silver (Ag), was evaluated in five indigenous fish species (namely, silver carp, common carp, mahseer, thela fish, and rainbow trout), by using atomic absorption spectrophotometer. It is proved from this study that, overall, mahseer and rainbow trout had high amount of zinc, whereas thela fish and silver carp had high concentration of copper, chromium, silver, nickel, and lead, while common carp had highest amount of iron contents. Furthermore, a tissue-specific discrimination among various fish species was observed, where higher metal concentrations were noticed in fish liver, with decreasing concentration in other organs like skin, gills, and finally the least contents in fish muscle. Multivariate data analysis showed not only a variation in heavy metals among the tissues but also discrimination among the selected fish species.

  19. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Sarita Singh

    2013-01-01

    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  20. Enhanced CO2 sorption and selectivity by functionalization of a NbO-type metal-organic framework with polarized benzothiadiazole moieties

    NARCIS (Netherlands)

    Song, C.; He, Y.; Li, B.; Ling, Y.; Wang, H.; Feng, Y.; Krishna, R.; Chen, B.

    2014-01-01

    A new NbO-type metal-organic framework ZJNU-40 incorporating highly polarized benzothiadiazole moieties exhibits a high CO2 uptake of 108 cm(3) g(-1) at 296 K and 1 atm, as well as good adsorption selectivities of CO2 over CH4 and N-2 at room temperature, which is superior to that of the analogous

  1. The Uncommon Channel-Based Ln-MOFs for Highly Selective Fe(3+) Detection and Superior Rhodamine B Adsorption.

    Science.gov (United States)

    Xing, Shanghua; Bing, Qiming; Song, Lifei; Li, Guanghua; Liu, Jingyao; Shi, Zhan; Feng, Shouhua; Xu, Ruren

    2016-11-02

    Two new isostructural 3D lanthanide-organic frameworks [H2 N(Me)2 ] [Ln3 (OH)(bpt)3 (H2 O)3 ] (DMF)2 ⋅(H2 O)4 (1-Ln; Ln=Sm and Eu) with a 1D channel (25 Å) have been successfully assembled from the rare trinuclear [Ln3 (OH)(COO)9 ] clusters and biphenyl-3,4',5-tricarboxylic acid (H3 bpt) and exhibit high stability towards water in the pH range 3-10. MOF 1-Eu is a promising luminescent probe for sensing Fe(3+) in aqueous solution and is also selective towards rhodamine B (RhB) with a superior adsorption capacity of 735 mg g(-1) , which is the highest among the reported Ln-MOFs for RhB removal so far. Periodic DFT calculations further confirmed the selective adsorption of rhodamine B over other dyes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Nonvacuum, maskless fabrication of a flexible metal grid transparent conductor by low-temperature selective laser sintering of nanoparticle ink.

    Science.gov (United States)

    Hong, Sukjoon; Yeo, Junyeob; Kim, Gunho; Kim, Dongkyu; Lee, Habeom; Kwon, Jinhyeong; Lee, Hyungman; Lee, Phillip; Ko, Seung Hwan

    2013-06-25

    We introduce a facile approach to fabricate a metallic grid transparent conductor on a flexible substrate using selective laser sintering of metal nanoparticle ink. The metallic grid transparent conductors with high transmittance (>85%) and low sheet resistance (30 Ω/sq) are readily produced on glass and polymer substrates at large scale without any vacuum or high-temperature environment. Being a maskless direct writing method, the shape and the parameters of the grid can be easily changed by CAD data. The resultant metallic grid also showed a superior stability in terms of adhesion and bending. This transparent conductor is further applied to the touch screen panel, and it is confirmed that the final device operates firmly under continuous mechanical stress.

  3. Diamine-appended metal-organic frameworks: enhanced formaldehyde-vapor adsorption capacity, superior recyclability and water resistibility.

    Science.gov (United States)

    Wang, Zhong; Wang, WenZhong; Jiang, Dong; Zhang, Ling; Zheng, Yali

    2016-07-28

    Capturing formaldehyde (HCHO) from indoor air with porous adsorbents still faces challenges due to their low uptake capacity, difficult regeneration, and especially, the sorption capacity reduction that is caused by the competitive adsorption of H2O when exposed to a humid atmosphere. In this work, MIL-101 is modified with ethylenediamine (ED) on its open-metal sites to substantially improve the HCHO adsorption properties. The HCHO uptake capacity of modified MIL-101 can be up to 5.49 mmol g(-1) in this study, which is among the highest-levels of various adsorbents reported thus far. Moreover, this modification both improved the material's recyclability and water resistibility, allowing for cyclic and selective tests with stable adsorption capacities, revealing the potential utility of amine-modified MOFs for indoor air purification.

  4. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    OpenAIRE

    2014-01-01

    Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstruct...

  5. Selective propene oxidation on mixed metal oxide catalysts

    CERN Document Server

    James, D W

    2002-01-01

    Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including coba...

  6. Selective and low temperature transition metal intercalation in layered tellurides

    Science.gov (United States)

    Yajima, Takeshi; Koshiko, Masaki; Zhang, Yaoqing; Oguchi, Tamio; Yu, Wen; Kato, Daichi; Kobayashi, Yoji; Orikasa, Yuki; Yamamoto, Takafumi; Uchimoto, Yoshiharu; Green, Mark A.; Kageyama, Hiroshi

    2016-12-01

    Layered materials embrace rich intercalation reactions to accommodate high concentrations of foreign species within their structures, and find many applications spanning from energy storage, ion exchange to secondary batteries. Light alkali metals are generally most easily intercalated due to their light mass, high charge/volume ratio and in many cases strong reducing properties. An evolving area of materials chemistry, however, is to capture metals selectively, which is of technological and environmental significance but rather unexplored. Here we show that the layered telluride T2PTe2 (T=Ti, Zr) displays exclusive insertion of transition metals (for example, Cd, Zn) as opposed to alkali cations, with tetrahedral coordination preference to tellurium. Interestingly, the intercalation reactions proceed in solid state and at surprisingly low temperatures (for example, 80 °C for cadmium in Ti2PTe2). The current method of controlling selectivity provides opportunities in the search for new materials for various applications that used to be possible only in a liquid.

  7. Effect of metal particles in cermets on spectral selectivity

    Science.gov (United States)

    Gao, J. D.; Zhao, C. Y.; Wang, B. X.

    2017-03-01

    Most cermet-based coatings achieve their solar selectivities by the tandem interference effect, which has been widely studied. This study focused on the spectral selectivity achieved by the scattering effect of metal particles in cermet-based coatings. Previous research proved that reasonable solar selectivities can be obtained for cermets in the regime of particles with a radius of the order of 100 nm, but their solar absorptance is low (Cr, Ni, and W particles with radii of 10 nm, 50 nm, 100 nm, and 200 nm, which were embedded in Al2O3 and occupied 5% of the volume fraction. It was found that by arranging different particles in different layers, a very high solar absorptance (95.6%) could be achieved. Since their thermal emittance (˜25% at 600 °C) was higher than that of normal coatings, these coatings are recommended to be used in solar absorbers that have a high concentration factor. Finally, the dependent scattering effect was qualitatively considered by the coupled-dipole approach. With a metal volume fraction of 5%, it was found that the effect of dependent scattering was small and should not change the conclusions made based on independent scattering.

  8. Selective gas adsorption and separation in metal-organic frameworks.

    Science.gov (United States)

    Li, Jian-Rong; Kuppler, Ryan J; Zhou, Hong-Cai

    2009-05-01

    Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal-organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

  9. Hot isostatic pressing of direct selective laser sintered metal components

    Science.gov (United States)

    Wohlert, Martin Steven

    2000-10-01

    A new manufacturing process combining the benefits of Selective Laser Sintering (SLS) and Hot Isostatic Pressing (HIP) has been developed to permit Rapid Prototyping of high performance metal components. The new process uses Direct Metal SLS to produce a gas impermeable HIP container from the same powdered material that will eventually compose the bulk of the part. The SLS generated capsule performs the functions of the sheet metal container in traditional HIP, but unlike a sheet metal container, the SLSed capsule becomes an integral part of the final component. Additionally, SLS can produce a capsule of far greater geometric complexity than can be achieved by sheet metal forming. Two high performance alloys, Ti-6Al-4V and Inconel 625, were selected for use in the development of the new process. HIP maps were constructed to predict the densification rate of the two materials during HIP processing. Comparison to experimentally determined densification behavior indicated that the maps provide a useful qualitative description of densification rates; however, the accuracy of quantitative predictions was greatly enhanced by tuning key material parameters based on a limited number of experimental HIP cycles. Microstructural characterization of SLS + HIP samples revealed two distinct regions within the components. The outer SLS processed capsule material exhibited a relatively coarse microstructure comparable to a cast, or multi-layer welded structure. No layer boundaries were discernible in the SLS material, with grains observed to grow epitaxially from previously deposited material. The microstructure of the HIP consolidated core material was similar to conventionally HIP processed powder materials, featuring a fine grain structure and preserved prior particle boundaries. The large variation in grain size between the capsule and core materials was reflected in hardness measurements conducted on the Alloy 625 material; however, the variation in hardness was less

  10. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Jacek PAWLICKI

    2014-06-01

    Full Text Available Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstructural examinations and identification of the fracture type enabled to describe a correlation between strain rate, strain and microstructure.

  11. Morphology and Orientation Selection of Non-metallic Inclusions in Electrified Molten Metal

    Science.gov (United States)

    Zhao, Z. C.; Qin, R. S.

    2017-10-01

    The effect of electric current on morphology and orientation selection of non-metallic inclusions in molten metal has been investigated using theoretical modeling and numerical calculation. Two geometric factors, namely the circularity ( fc ) and alignment ratio ( fe ) were introduced to describe the inclusions shape and configuration. Electric current free energy was calculated and the values were used to determine the thermodynamic preference between different microstructures. Electric current promotes the development of inclusion along the current direction by either expatiating directional growth or enhancing directional agglomeration. Reconfiguration of the inclusions to reduce the system electric resistance drives the phenomena. The morphology and orientation selection follow the routine to reduce electric free energy. The numerical results are in agreement with our experimental observations.

  12. Honey bee lines selected for high propolis production also have superior hygienic behavior and increased honey and pollen stores.

    Science.gov (United States)

    Nicodemo, D; De Jong, D; Couto, R H N; Malheiros, E B

    2013-12-19

    Honey bees use propolis to defend against invaders and disease organisms. As some colonies produce much more propolis than others, we investigated whether propolis collecting is associated with disease resistance traits, including hygienic behavior and resistance to the parasitic bee mite, Varroa destructor. The three highest (HP) and three lowest propolis-producing (LP) colonies among 36 Africanized honey bee colonies were initially selected. Queens and drones from these colonies were crossed through artificial insemination to produce five colonies of each of the following crosses: HP♀ X HP♂, LP♀ X HP♂, HP♀ X LP♂, and LP♀ X LP♂. Colonies headed by HP♀ X HP♂ queens produced significantly more propolis than those with HP♀ X LP♂ and LP♀ X HP♂ queens and these in turn produced significantly more propolis than those headed by LP♀ X LP♂ queens. The brood cell uncapping rate of the high-propolis-producing colonies in the hygienic behavior test was significantly superior to that of the other groups. The LP X LP group was significantly less hygienic than the two HP X LP crosses, based on the evaluation of the rate of removal of pin-killed pupae. The HP X HP colonies were significantly more hygienic than the other crosses. No significant differences were found in mite infestation rates among the groups of colonies; although overall, colony infestation rates were quite low (1.0 to 3.2 mites per 100 brood cells), which could have masked such effects. Honey and pollen stores were significantly and positively correlated with propolis production.

  13. Rapid Isolation of the Trichoderma Strain with Higher Degrading Ability of a Filter Paper and Superior Proliferation Characteristics Using Avicel Plates and the Double-Layer Selection Medium

    Science.gov (United States)

    Toyama, Hideo; Nakano, Megumi; Satake, Yuuki; Toyama, Nobuo

    The cost of cellulase is still a problem for bioethanol production. As the cellulase of Trichoderma reesei is applicable for producing ethanol from cellulosic materials, the cellulase productivity of this fungus should be increased. Therefore, we attempted to develop a system to isolate the strain with higher degrading ability of a filter paper and superior proliferation characteristics among the conidia treated with the mitotic arrester, colchicine. When green mature conidia of T. reesei RUT C-30 were swollen, autopolyploidized, and incubated in the double-layer selection medium containing Avicel, colonies appeared on the surface earlier than the original strain. When such colonies and the original colony were incubated on the Avicel plates, strain B5, one of the colonies derived from the colchicinetreated conidia, showed superior proliferation characteristics. Moreover, when strain B5 and the original strain were compared in the filter paper degrading ability and the cellulose hydrolyzing activity, strain B5 was also superior to the original strain. It was suspected that superior proliferation characteristics of strain B5 reflects higher filter paper degrading ability. Thus, we concluded that the Trichoderma strain with higher degrading ability of a filter paper and superior proliferation characteristics can be isolated using Avicel plates and the double-layer selection medium.

  14. Rapid isolation of the Trichoderma strain with higher degrading ability of a filter paper and superior proliferation characteristics using avicel plates and the double-layer selection medium.

    Science.gov (United States)

    Toyama, Hideo; Nakano, Megumi; Satake, Yuuki; Toyama, Nobuo

    2008-03-01

    The cost of cellulase is still a problem for bioethanol production. As the cellulase of Trichoderma reesei is applicable for producing ethanol from cellulosic materials, the cellulase productivity of this fungus should be increased. Therefore, we attempted to develop a system to isolate the strain with higher degrading ability of a filter paper and superior proliferation characteristics among the conidia treated with the mitotic arrester, colchicine. When green mature conidia of T. reesei RUT C-30 were swollen, autopolyploidized, and incubated in the double-layer selection medium containing Avicel, colonies appeared on the surface earlier than the original strain. When such colonies and the original colony were incubated on the Avicel plates, strain B5, one of the colonies derived from the colchicine-treated conidia, showed superior proliferation characteristics. Moreover, when strain B5 and the original strain were compared in the filter paper degrading ability and the cellulose hydrolyzing activity, strain B5 was also superior to the original strain. It was suspected that superior proliferation characteristics of strain B5 reflects higher filter paper degrading ability. Thus, we concluded that the Trichoderma strain with higher degrading ability of a filter paper and superior proliferation characteristics can be isolated using Avicel plates and the double-layer selection medium.

  15. Encapsulation of nanoscale metal oxides into an ultra-thin Ni matrix for superior Li-ion batteries: a versatile strategy.

    Science.gov (United States)

    Zhu, Jianhui; Jiang, Jian; Ai, Wei; Fan, Zhanxi; Huang, Xintang; Zhang, Hua; Yu, Ting

    2014-11-01

    Li-ion batteries' (LIBs) performance proves to be highly correlated with ionic and electrical transport kinetics in electrodes. Although continual progress has been achieved in rational design of ideal electrode systems, their energy density, cyclic endurance and productivity are still far from perfect for practical use. Herein we propose an interesting, facile and versatile strategy to encapsulate various nanoscale metal oxides (covering both nanopowders and nanostructured arrays) into an ultrathin Ni matrix (metal oxide@Ni) for superior LIBs. Evolutions of such metal oxide@Ni hybrids (taking MnO@Ni and CoO@Ni as models) are thoroughly studied by monitoring their whole fabrication process. Putting "armors" on nanoscale metal oxides is thought helpful for the promotion of the LIB performance since the outer Ni matrix provides both mechanical protection against huge volume changes and effective routes for electron transfer. As a proof-of-concept demonstration, all metal oxide@Ni hybrid electrodes exhibit drastic improvements in the capacity retention (e.g. ∼452% capacity rise for the MnO@Ni case while ∼551% for CoO@Ni NWs), long-term cyclic stability and rate capabilities. This designed strategy can be further extended to make other advanced oxide@metal hybrids, not only for LIBs but also for other potential fields.

  16. Organic Membranes for Selectivity Enhancement of Metal Oxide Gas Sensors

    Directory of Open Access Journals (Sweden)

    Thorsten Graunke

    2016-01-01

    Full Text Available We present the characterization of organic polyolefin and thermoplastic membranes for the enhancement of the selectivity of metal oxide (MOX gas sensors. The experimental study is done based on theoretical considerations of the membrane characteristics. Through a broad screening of dense symmetric homo- and copolymers with different functional groups, the intrinsic properties such as the mobility or the transport of gases through the matrix were examined in detail. A subset of application-relevant gases was chosen for the experimental part of the study: H2, CH4, CO, CO2, NO2, ethanol, acetone, acetaldehyde, and water vapor. The gases have similar kinetic diameters and are therefore difficult to separate but have different functional groups and polarity. The concentration of the gases was based on the international indicative limit values (TWA, STEL. From the results, a simple relationship was to be found to estimate the permeability of various polar and nonpolar gases through gas permeation (GP membranes. We used a broadband metal oxide gas sensor with a sensitive layer made of tin oxide with palladium catalyst (SnO2:Pd. Our aim was to develop a low-cost symmetrical dense polymer membrane to selectively detect gases with a MOX sensor.

  17. Lanthanide metal-organic frameworks as selective microporous materials for adsorption of heavy metal ions.

    Science.gov (United States)

    Jamali, Abbas; Tehrani, Alireza Azhdari; Shemirani, Farzaneh; Morsali, Ali

    2016-06-14

    Four microporous lanthanide metal-organic frameworks (MOFs), namely Ln(BTC)(H2O)(DMF)1.1 (Ln = Tb, Dy, Er and Yb, DMF = dimethylformamide, H3BTC = benzene-1,3,5-tricarboxylic acid), have been used for selective adsorption of Pb(ii) and Cu(ii). Among these MOFs, the Dy-based MOF shows better adsorption property and selectivity toward Pb(ii) and Cu(ii) ions. Adsorption isotherms indicate that sorption of Pb(ii) and Cu(ii) on MOFs is via monolayer coverage. Preconcentration is based on solid-phase extraction in which MOFs were rapidly injected into water samples and adsorption of metal ions was rapid because of good contact with analyte; then adsorbed Pb(ii) and Cu(ii) ions were analyzed by FAAS. The optimized methodology represents good linearity between 1 and 120 μg L(-1) and detection limit of 0.4 and 0.26 μg L(-1) for Pb(ii) and Cu(ii), respectively. Subsequently the method was evaluated for preconcentration of target metal ions in some environmental water samples.

  18. Anion separation by selective crystallization of metal-organic frameworks.

    Science.gov (United States)

    Custelcean, Radu; Haverlock, Tamara J; Moyer, Bruce A

    2006-08-07

    A novel approach for the separation of anions from aqueous mixtures was demonstrated, which involves their selective crystallization with metal-organic frameworks (MOFs) containing urea functional groups. Self-assembly of Zn2+ with the N,N'-bis(m-pyridyl)urea (BPU) linker results in the formation of one-dimensional MOFs including various anions for charge balance, which interact to different extents with the zinc nodes and the urea hydrogen-bonding groups, depending on their coordinating abilities. Thus, Cl-, Br-, I-, and SO4(2-), in the presence of BPU and Zn2+, form MOFs from water, in which the anions coordinate the zinc and are hydrogen-bonded to the urea groups, whereas NO3- and ClO4- anions either do not form MOFs or form water-soluble discrete coordination complexes under the same conditions. X-ray diffraction, FTIR, and elemental analysis of the coordination polymers precipitated from aqueous mixtures containing equivalent amounts of these anions indicated total exclusion of the oxoanions and selective crystallization of the halides in the form of solid solutions with the general composition ZnCl(x)Br(y)I(z).BPU (x + y + z = 2), with an anti-Hofmeister selectivity. The concomitant inclusion of the halides in the same structural frameworks facilitates the rationalization of the observed selectivity on the basis of the diminishing interactions with the zinc and urea acidic centers in the MOFs when going from Cl- to I-, which correlates with decreasing anionic charge density in the same order. The overall crystal packing efficiency of the coordination frameworks, which ultimately determines their solubility, also plays an important role in the anion crystallization selectivity under thermodynamic equilibration.

  19. Modified accumulation of selected heavy metals in Bt transgenic rice

    Institute of Scientific and Technical Information of China (English)

    WANG Haiyan; HUANG Jianzhong; YE Qingfu; WU Dianxing; CHEN Ziyuan

    2009-01-01

    Safety assessment of genetically modified crops generally does not take into account the potential hazard of altered patterns of heavy metal accumulation in plants.A pot experiment was conducted under greenhouse conditions to evaluate the impact of heavy metal amendments on the accumulation of Cd,Cu,Pb and Zn in a Bt transgenic rice Ke-Ming-Dao (KMD) and its wild-type Xiushui 11 (Xs11).In control soils,significant difference was only found in contents of Cu (p < 0.01) and Pb (p < 0.05) in straw between KMD and Xs11.At three levels of Cd amendments (5,10,and 20 mg/kg),the Cd contents in grain and straw of KMD were significantly higher than those of Xs11,and all grain Cd contents were significantly higher than the international criteria (0.2-0.4 mg/kg) as specified by the Codex Alimentarius Commission (CAC).These results implied that it may be unsafe for growing Bt transgenic rice in heavily Cd-polluted areas.No significant difference in Zn was found between the two varieties with the exception of roots at Zn amendment level of 600 mg/kg,while Pb contents in KMD were much higher in the straw at the lead amendment level of 1000 mg/kg and in the root at 250 mg Pb/kg.Data on the heavy metal accumulation patterns for the genetically modified rice may be used for the selection of growing areas as well as for plant residue management for Bt rice.

  20. Heavy metal concentrations of selected public parks of Istanbul City

    Directory of Open Access Journals (Sweden)

    Demir Goksel

    2016-01-01

    Full Text Available Many cities, especially larger metropolises, parks are very important recreational areas where people usually have closer contact with flora. Therefore, the pollution level in the parks can have a greater effect on human health. Heavy metals are ubiquitous with the environment, as a result of both natural and anthropogenic activities, and humans are exposed to them through various pathways. Essentially, these areas are assumed to be less exposed to routine contaminants, but especially in metropolises, this assumption could prove false considering these areas are stuck within the confines of a city full of pollutant activity such as intense traffic. In this study; the relationships between heavy metal pollution levels (Cd, Cr, Cu, Ni, Pb, Zn and the pH and electrical conductivity (EC of soil samples were investigated from the parks on the Asian side of Istanbul. For this purpose, the most frequently visited 16 parks were selected as sampling sites. In the second part of the study, linear correlation is used for the data analysis.

  1. Selective organic synthesis over metal cation-exchanged clay catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Tateiwa, J.; Uemura, S. [Kyoto University, Kyoto (Japan)

    1997-09-01

    Results of recent studies conducted by the authors are reviewed on the use, as catalysts, of metal cation-exchanged montmorillonite (M{sup n+}-mont), a modified natural clay with a layer structure, and metal cation-exchanged fluor-tetrasilicic mica (M{sup n+}-TSM), a synthetic clay with a layer structure, for the following organic synthesis: (1) Friedel-Crafts alkylation of phenol with 4-hydroxybutan-2-one to produce 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone), (2) rearrangement of alkyl phenyl ethers to corresponding alkylphenols, (3) aromatic alkylation of phenol with aldehydes and ketones to produce corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) and alkylphenols, respectively, (4) a facile and an almost quantitative substrate-selective acetalization, (5) alkane oxidation with aqueous tert-butyl hydroperoxide, (6) Prins reaction of styrenes with aldehydes using clay as a Bronsted acid, and (7) inter-and intra-molecular carbonyl-ene reaction using clay as a Lewis acid in condition similar to that of Prins reaction. In almost all cases, the clay catalysts could be regenerated and reused several times, after filtration, washing and drying. 42 refs., 20 figs., 3 tabs.

  2. Selective Laser Melting of Metal Powder Of Steel 3161

    Science.gov (United States)

    Smelov, V. G.; Sotov, A. V.; Agapovichev, A. V.; Tomilina, T. M.

    2016-08-01

    In this article the results of experimental study of the structure and mechanical properties of materials obtained by selective laser melting (SLM), metal powder steel 316L was carried out. Before the process of cultivation of samples as the input control, the morphology of the surface of the powder particles was studied and particle size analysis was carried out. Also, 3D X-ray quality control of the grown samples was carried out in order to detect hidden defects, their qualitative and quantitative assessment. To determine the strength characteristics of the samples synthesized by the SLM method, static tensile tests were conducted. To determine the stress X-ray diffraction analysis was carried out in the material samples.

  3. Non-small cell lung carcinoma of the superior sulcus : Favourable outcomes of combined modality treatment in carefully selected patients

    NARCIS (Netherlands)

    Kappers, I.; Belderbos, J. S. A.; Burgers, J. A.; van Zandwijk, N.; Groen, H. J. M.; Klomp, H. M.

    The combination of radiotherapy and concurrent chemotherapy followed by surgery (trimodality treatment) is currently regarded as optimal treatment for non-small cell lung cancer of the superior sulcus (SST) or Pancoast tumour. The possibility to administer intensive combined modality treatment is

  4. Fabrication and magnetic-induced aggregation of Fe{sub 3}O{sub 4}–noble metal composites for superior SERS performances

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Zibao; Zhao, Aiwu, E-mail: awzhao@iim.ac.cn; Zhang, Maofeng; Wang, Dapeng; Guo, Hongyan; Tao, Wenyu; Gao, Qian; Mao, Ranran; Liu, Erhu [Chinese Academy of Sciences, Institute of Intelligent Machines (China)

    2013-11-15

    Fe{sub 3}O{sub 4}–noble metal composites were obtained by combining Au, Ag nanoparticles (NPs) with 3-aminopropyltrimethoxysilane-functionalized Fe{sub 3}O{sub 4} NPs. UV–Visible absorption spectroscopy demonstrates the obtained Fe{sub 3}O{sub 4}–noble metal composites inherit the typical surface plasmon resonance bands of Au, Ag at 533 and 453 nm, respectively. Magnetic measurements also indicated that the superparamagnetic Fe{sub 3}O{sub 4}–noble metal composites have excellent magnetic response behavior. A magnetic-induced idea was introduced to change their aggregated states and take full advantage of their surface-enhanced Raman scattering (SERS) performances. Under the induction of an external magnetic field, the bifunctional Fe{sub 3}O{sub 4}–noble metal aggregates exhibit the unique superiority in SERS detection of Rhodamine 6G (R6G), compared with the naturally dispersed Au, Ag NPs. Especially, the detection limit of the Fe{sub 3}O{sub 4}–Ag aggregates for R6G is as low as 10{sup −14} M, and the calculated EF reaches up to 1.2 × 10{sup 6}, which meets the requirements for trace detection of analytes. Furthermore, the superiority could be extended to sensitive detection of other organic molecules, such as 4-mercaptopyridine. This work provides a new insight for active adjustment of the aggregated states of SERS substrates and the optimization of SERS performances.

  5. Characteristics and possibilities of software tool for metal-oxide surge arresters selection

    Directory of Open Access Journals (Sweden)

    Đorđević Dragan

    2012-01-01

    Full Text Available This paper presents a procedure for the selection of metal-oxide surge arresters based on the instructions given in the Siemens and ABB catalogues, respecting their differences and the characteristics and possibilities of the software tool. The software tool was developed during the preparation of a Master's thesis titled, 'Automation of Metal-Oxide Surge Arresters Selection'. An example is presented of the selection of metal-oxide surge arresters using the developed software tool.

  6. Core–shell heterostructured metal oxide arrays enable superior light-harvesting and hysteresis-free mesoscopic perovskite solar cells

    KAUST Repository

    Mahmood, Khalid

    2015-01-01

    To achieve highly efficient mesoscopic perovskite solar cells (PSCs), the structure and properties of an electron transport layer (ETL) or material (ETM) have been shown to be of supreme importance. Particularly, the core-shell heterostructured mesoscopic ETM architecture has been recognized as a successful electrode design, because of its large internal surface area, superior light-harvesting efficiency and its ability to achieve fast charge transport. Here we report the successful fabrication of a hysteresis-free, 15.3% efficient PSC using vertically aligned ZnO nanorod/TiO2 shell (ZNR/TS) core-shell heterostructured ETMs for the first time. We have also added a conjugated polyelectrolyte polymer into the growth solution to promote the growth of high aspect ratio (AR) ZNRs and substantially improve the infiltration of the perovskite light absorber into the ETM. The PSCs based on the as-synthesized core-shell ZnO/TiO2 heterostructured ETMs exhibited excellent performance enhancement credited to the superior light harvesting capability, larger surface area, prolonged charge-transport pathways and lower recombination rate. The unique ETM design together with minimal hysteresis introduces core-shell ZnO/TiO2 heterostructures as a promising mesoscopic electrode approach for the fabrication of efficient PSCs. This journal is © The Royal Society of Chemistry.

  7. Selective Catalysis in Nanoparticle Metal-Organic Framework Composites

    Science.gov (United States)

    Stephenson, Casey Justin

    The design of highly selective catalysts are becoming increasingly important, especially as chemical and pharmaceutical industries seek to improve atom economy and minimize energy intensive separations that are often required to separate side products from the desired product. Enzymes are among the most selective of all catalysts, generally operating through molecular recognition whereby an active site analogous to a lock and the substrate is analogous to a key. The assembly of a porous, crystalline material around a catalytically active metal particle could serve as an artificial enzyme. In this vein, we first synthesized the polyvinylpyrrolidone (PVP) coated nanoparticles of interest and then encapsulated them within zeolitic imidazolate framework 8 or ZIF-8. 2.8 nm Pt-PVP nanoparticles, which were encapsulated within ZIF-8 to form Pt ZIF-8 composite. Pt ZIF-8 was inactive for the hydrogenation of cyclic olefins such as cis-cyclooctene and cis-cyclohexene while the composite proved to be a highly selective catalyst for the hydrogenation of terminal olefins, hydrogenating trans-1,3-hexadiene to 3-hexene in 95% selectivity after 24 hours under 1 bar H2. We extended our encapsulation method to sub-2 nm Au nanoparticles to form Au ZIF-8. Au ZIF-8 served as a highly chemoselective catalyst for the hydrogenation of crotonaldehyde an alpha,beta-unsaturated aldehyde, to crotyl alcohol an alpha,beta-unsaturated alcohol, in 90-95% selectivity. In order to investigate nanoparticle size effects on selectivity, 6-10 nm Au nanoparticles were encapsulated within ZIF-8 to form Au6 ZIF-8. Control catalysts with nanoparticles supported on the surface of ZIF-8 were synthesized as well, Au/ZIF-8 and Au6/ZIF-8. Au6 ZIF-8 hydrogenated crotonaldehyde in 85% selectivity towards the unsaturated alcohol. Catalysts with nanoparticles supported on the exterior of ZIF-8 were far less selective towards the unsaturated alcohol. Post-catalysis transmission electron microscopy analysis of Au ZIF

  8. Selective laser extraction of the Pt group metals

    Energy Technology Data Exchange (ETDEWEB)

    Fadeeva, S.; Krynetsky, B.; Prokhorov, A.; Zhidkov, A. [General Physics Institute, Russian Academy of Science, Moscow (Russian Federation)

    1995-11-15

    The interest to the platinum-group metals extraction from solutions, especially industry waste, is stimulated by their extraordinary chemical inert. The traditional chemical methods of the extraction are uneffective. Have been investigated process of the extraction of metal Pt-group from acid solutions. Discussed processes reduction of noble metals by resonance laser action.

  9. Selection of superior salt/boron tolerant Stanleya pinnata genotypes and quantification of their selenium phytoremediation abilities in drainage sediment.

    Science.gov (United States)

    The semi-metallic mineral Se, a naturally-occurring trace element, is primarily found as selenate originating from sedimentary and shale rock formations, e.g., in the western side of the San Joaquin Valley of central California (WSJV). Because selenate-Se is water soluble, bioavailable and biomagnif...

  10. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zongchao [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Wang, Fengqin, E-mail: wangfengqin@tjpu.edu.cn [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Lin, Xiangyi [Suzhou Huihe Pharmaceutical Limited Company, Suzhou 215200 (China); Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun [College of Environment and Chemical Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, Yongnan [College of Materials and Engineering & Key Lab of Hollow Fiber Membrane Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Guodong [The State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023 (China)

    2015-12-15

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn{sub 3}L{sub 3}(DMF){sub 2} (1) and Zn{sub 3}L{sub 3}(DMA){sub 2}(H{sub 2}O){sub 3} (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe{sup 3+} and Al{sup 3+} by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe{sup 3+}. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe{sup 3+} or Al{sup 3+}.

  11. Density of states-based design of metal oxide thin-film transistors for high mobility and superior photostability.

    Science.gov (United States)

    Kim, Hyun-Suk; Park, Joon Seok; Jeong, Hyun-Kwang; Son, Kyoung Seok; Kim, Tae Sang; Seon, Jong-Baek; Lee, Eunha; Chung, Jae Gwan; Kim, Dae Hwan; Ryu, Myungkwan; Lee, Sang Yoon

    2012-10-24

    A novel method to design metal oxide thin-film transistor (TFT) devices with high performance and high photostability for next-generation flat-panel displays is reported. Here, we developed bilayer metal oxide TFTs, where the front channel consists of indium-zinc-oxide (IZO) and the back channel material on top of it is hafnium-indium-zinc-oxide (HIZO). Density-of-states (DOS)-based modeling and device simulation were performed in order to determine the optimum thickness ratio within the IZO/HIZO stack that results in the best balance between device performance and stability. As a result, respective values of 5 and 40 nm for the IZO and HIZO layers were determined. The TFT devices that were fabricated accordingly exhibited mobility values up to 48 cm(2)/(V s), which is much elevated compared to pure HIZO TFTs (∼13 cm(2)/(V s)) but comparable to pure IZO TFTs (∼59 cm(2)/(V s)). Also, the stability of the bilayer device (-1.18 V) was significantly enhanced compared to the pure IZO device (-9.08 V). Our methodology based on the subgap DOS model and simulation provides an effective way to enhance the device stability while retaining a relatively high mobility, which makes the corresponding devices suitable for ultradefinition, large-area, and high-frame-rate display applications.

  12. Average and local structure of selected metal deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Soerby, Magnus H.

    2005-07-01

    The main topic of this thesis is improved understanding of site preference and mutual interactions of deuterium (D) atoms in selected metallic metal deuterides. The work was partly motivated by reports of abnormally short D-D distances in RENiInD1.33 compounds (RE = rear-earth element; D-D {upsilon} square root 1.6 Aa) which show that the so-called Switendick criterion that demands a D-D separation of at least 2 Aa, is not a universal rule. The work is experimental and heavily based on scattering measurements using x-rays (lab and synchrotron) and neutrons. In order to enhance data quality, deuterium is almost exclusively used instead of natural hydrogen in sample preparations. The data-analyses are in some cases taken beyond ''conventional'' analysis of the Bragg scattering, as the diffuse scattering contains important information on D-D distances in disordered deuterides (Paper 3 and 4). A considerable part of this work is devoted to determination of the crystal structure of saturated Zr2Ni deuteride, Zr2NiD-4.8. The structure remained unsolved when only a few months remained of the scholarship. The route to the correct structure was found in the last moment. In Chapter II this winding road towards the structure determination is described; an interesting exercise in how to cope with triclinic superstructures of metal hydrides. The solution emerged by combining data from synchrotron radiation powder x-ray diffraction (SR-PXD), powder neutron diffraction (PND) and electron diffraction (ED). The triclinic crystal structure, described in space group P1 , is fully ordered with composition Zr4Ni2D9 (Zr2NiD4.5). The unit cell is doubled as compared to lower Zr2Ni deuterides due to a deuterium superstructure: asuper = a, bsuper = b - c, csuper = b + c. The deviation from higher symmetry is very small. The metal lattice is pseudo-I-centred tetragonal and the deuterium lattice is pseudo-C-centred monoclinic. The deuterium site preference in Zr2Ni

  13. Encapsulation of Bimetallic Metal Nanoparticles into Robust Zirconium-Based Metal-Organic Frameworks: Evaluation of the Catalytic Potential for Size-Selective Hydrogenation.

    Science.gov (United States)

    Rösler, Christoph; Dissegna, Stefano; Rechac, Victor L; Kauer, Max; Guo, Penghu; Turner, Stuart; Ollegott, Kevin; Kobayashi, Hirokazu; Yamamoto, Tomokazu; Peeters, Daniel; Wang, Yuemin; Matsumura, Syo; Van Tendeloo, Gustaaf; Kitagawa, Hiroshi; Muhler, Martin; Llabrés I Xamena, Francesc X; Fischer, Roland A

    2017-03-13

    The realization of metal nanoparticles (NPs) with bimetallic character and distinct composition for specific catalytic applications is an intensively studied field. Due to the synergy between metals, most bimetallic particles exhibit unique properties that are hardly provided by the individual monometallic counterparts. However, as small-sized NPs possess high surface energy, agglomeration during catalytic reactions is favored. Sufficient stabilization can be achieved by confinement of NPs in porous support materials. In this sense, metal-organic frameworks (MOFs) in particular have gained a lot of attention during the last years; however, encapsulation of bimetallic species remains challenging. Herein, the exclusive embedding of preformed core-shell PdPt and RuPt NPs into chemically robust Zr-based MOFs is presented. Microstructural characterization manifests partial retention of the core-shell systems after successful encapsulation without harming the crystallinity of the microporous support. The resulting chemically robust NP@UiO-66 materials exhibit enhanced catalytic activity towards the liquid-phase hydrogenation of nitrobenzene, competitive with commercially used Pt on activated carbon, but with superior size-selectivity for sterically varied substrates. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Selective retention of basic compounds by metal aquo-ion affinity chromatography.

    Science.gov (United States)

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki

    2014-10-01

    A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity.

  15. Resources of Selected Metals in Parent Bodies of Ordinary Chondrites

    Science.gov (United States)

    Łuszczek, K.; Przylibski, T. A.

    2013-09-01

    Certain metals in OC exceed mean content of these metals in the Earth’s crust. Content of Fe and Ni in OC is even higher than in Earth's deposits. Parent bodies of OC, can be regarded as Fe-Ni deposits, while accompanying ores are Mn,Cr,Co,Cu,Ag,Au.

  16. Genotype and phenotypes of an intestine-adapted Escherichia coli K-12 mutant selected by animal passage for superior colonization.

    Science.gov (United States)

    Fabich, Andrew J; Leatham, Mary P; Grissom, Joe E; Wiley, Graham; Lai, Hongshing; Najar, Fares; Roe, Bruce A; Cohen, Paul S; Conway, Tyrrell

    2011-06-01

    We previously isolated a spontaneous mutant of Escherichia coli K-12, strain MG1655, following passage through the streptomycin-treated mouse intestine, that has colonization traits superior to the wild-type parent strain (M. P. Leatham et al., Infect. Immun. 73:8039-8049, 2005). This intestine-adapted strain (E. coli MG1655*) grew faster on several different carbon sources than the wild type and was nonmotile due to deletion of the flhD gene. We now report the results of several high-throughput genomic analysis approaches to further characterize E. coli MG1655*. Whole-genome pyrosequencing did not reveal any changes on its genome, aside from the deletion at the flhDC locus, that could explain the colonization advantage of E. coli MG1655*. Microarray analysis revealed modest yet significant induction of catabolic gene systems across the genome in both E. coli MG1655* and an isogenic flhD mutant constructed in the laboratory. Catabolome analysis with Biolog GN2 microplates revealed an enhanced ability of both E. coli MG1655* and the isogenic flhD mutant to oxidize a variety of carbon sources. The results show that intestine-adapted E. coli MG1655* is more fit than the wild type for intestinal colonization, because loss of FlhD results in elevated expression of genes involved in carbon and energy metabolism, resulting in more efficient carbon source utilization and a higher intestinal population. Hence, mutations that enhance metabolic efficiency confer a colonization advantage.

  17. Stretchable, Transparent Electrodes as Wearable Heaters Using Nanotrough Networks of Metallic Glasses with Superior Mechanical Properties and Thermal Stability.

    Science.gov (United States)

    An, Byeong Wan; Gwak, Eun-Ji; Kim, Kukjoo; Kim, Young-Cheon; Jang, Jiuk; Kim, Ju-Young; Park, Jang-Ung

    2016-01-13

    Mechanical robustness, electrical and chemical reliabilities of devices against large deformations such as bending and stretching have become the key metrics for rapidly emerging wearable electronics. Metallic glasses (MGs) have high elastic limit, electrical conductivity, and corrosion resistance, which can be promising for applications in wearable electronics. However, their applications in wearable electronics or transparent electrodes have not been extensively explored so far. Here, we demonstrate stretchable and transparent electrodes using CuZr MGs in the form of nanotrough networks. MG nanotroughs are prepared by electrospinning and cosputtering process, and they can be transferred to various desired substrates, including stretchable elastomeric substrates. The resulting MG nanotrough network is first utilized as a stretchable transparent electrode, presenting outstanding optoelectronic (sheet resistance of 3.8 Ω/sq at transmittance of 90%) and mechanical robustness (resistance change less than 30% up to a tensile strain of 70%) as well as excellent chemical stability against hot and humid environments (negligible degradation in performance for 240 h in 85% relative humidity and 85 °C). A stretchable and transparent heater based on the MG nanotrough network is also demonstrated with a wide operating temperature range (up to 180 °C) and excellent stretchability (up to 70% in the strain). The excellent mechanical robustness of these stretchable transparent electrode and heater is ascribed to the structural configuration (i.e., a nanotrough network) and inherent high elastic limit of MGs, as supported by experimental results and numerical analysis. We demonstrate their real-time operations on human skin as a wearable, transparent thermotherapy patch controlled wirelessly using a smartphone as well as a transparent defroster for an automobile side-view mirror, suggesting a promising strategy toward next-generation wearable electronics or automobile

  18. 广东省台湾相思优树选择技术分析%Study on criterion for selecting Acacia confusa superior trees

    Institute of Scientific and Technical Information of China (English)

    肖泽鑫; 柳泽鑫; 邹桂逢; 彭剑华; 罗超; 陈翠蓉; 詹潮安

    2015-01-01

    Based on quantity indexes (DBH, tree height and individual volume), in combination with quality indexes (under-branch height, stem straightness, tapering grade, canopy density and branch size), the selection criterion of Acacia confusa superior trees was established by using method of ifve-dominant-trees contrast. The investigations on A. confusa plus trees selection were carried out by using the designed superior tree selection criteria in nine test sites of Guangdong province, such as Shantou Xihuan Mountain, Chaozhou Gubi Mountain and Xianchun Village, Huizhou Xihu Park Baota Mountain and so on. The 43 candidate trees and 215 contrast trees were ifltered out for statistical analysis. According to the results, a set of technical standards of A. confusa superior trees selection for Guangdong province were summarized as follows:the selected excellent tree’s tree height should be greater than that of 5 average dominant tree, the selected excellent tree’s DBH should be greater than or equal to 5 1.17 times of the average DBH of 5 average dominant tree, the selected excellent tree’s single tree timber volume should be greater than or equal to 1.52 times of that of 5 average dominant tree per tree, and the tree form quality index 0.33A (tapering grade score)+0.32B (stem straightness score)+0.35C (canopy density score) should be greater than 2. Lastly, nineteen superior trees in 43 candidate trees were selected according this criterion and the selected ratio was 44.2%.%采用5株优势木对比法,以胸径、树高、材积为生长指标,同时结合枝下高、通直度、尖削度、枝叶浓密度和侧枝粗等形质指标,在广东省汕头潮阳西环山、潮州饶平石壁山和仙春村、惠州西湖公园宝塔山等9个地点开展了台湾相思的优树调查研究。总共筛选了43株候选优树和215株优势木进行统计分析,并归纳总结出了广东省台湾相思优树选择的技术标准,即优树树高>5株优势木平

  19. Determination of selected heavy metals in inland fresh water of ...

    African Journals Online (AJOL)

    Agadaga

    significant negative impact on the water quality. Key words: Heavy ... fish, and for such in-stream uses as recreation, ... adverse effects of pollutants such as heavy metals is ... through Kebbi State and flows through to the Atlantic Ocean. The.

  20. Selected Metals in Canned Fish Consumed in Iran

    OpenAIRE

    2014-01-01

    Background: The presence of heavy metals in the environment could constitute a hazard to food security and public health. These can be accumulated in aquatic animals such as fish. Canned fish is consumed regularly in many countries. In this study, the levels of heavy metals Cu, Ni, Fe and Cr were evaluated in commercial canned fish products that are commonly consumed in Iran. The canned fish studied were longtail tuna, Kawakawa, Kilka and yellowfin tuna. Methods: Samples of four popular br...

  1. Strategic role of selected noble metal nanoparticles in medicine.

    Science.gov (United States)

    Rai, Mahendra; Ingle, Avinash P; Birla, Sonal; Yadav, Alka; Santos, Carolina Alves Dos

    2016-09-01

    Noble metals and their compounds have been used as therapeutic agents from the ancient time in medicine for the treatment of various infections. Recently, much progress has been made in the field of nanobiotechnology towards the development of different kinds of nanomaterials with a wide range of applications. Among the metal nanoparticles, noble metal nanoparticles have demonstrated potential biomedical applications. Due to the small size, nanoparticles can easily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. Noble metal nanoparticles inspired the researchers due to their remarkable role in detection and treatment of dreadful diseases. In this review, we have attempted to focus on the biomedical applications of noble metal nanoparticles particularly, silver, gold, and platinum in diagnosis and treatment of dreaded diseases such as cancer, human immunodeficiency virus (HIV), tuberculosis (TB), and Parkinson disease. In addition, the role of silver nanoparticles (AgNPs) such as novel antimicrobials, gold nanoparticles (AuNPs) such as efficient drug carrier, uses of platinum nanoparticles (PtNPs) in bone allograft, dentistry, etc. have been critically reviewed. Moreover, the toxicity due to the use of metal nanoparticles and some unsolved challenges in the field have been discussed with their possible solutions.

  2. Isolation, screening, characterization, and selection of superior rhizobacterial strains as bioinoculants for seedling emergence and growth promotion of Mandarin orange (Citrus reticulata Blanco).

    Science.gov (United States)

    Thokchom, Elizabeth; Kalita, Mohan Chandra; Talukdar, Narayan Chandra

    2014-02-01

    Mandarin orange (MO) is an important fruit crop of tropical and subtropical regions of the world. A total of 217 morphologically distinct rhizobacteria from MO orchards in 3 states of northeastern India were isolated and analyzed for 4 plant-growth-promoting (PGP) attributes: nitrogen fixation, production of indole acetic acid like substances, solubilization of phosphate, and ability to antagonize pathogenic fungi. Isolates were ranked based on in-vitro-assayed PGP attributes, and 10 superior isolates were selected to test their effect on seedling emergence and seedling growth in a completely randomized pot experiment. These 10 isolates increased seedling emergence over a noninoculated control within 45 days after sowing. Five isolates, namely RCE1, RCE2, RCE3, RCE5, and RCE7, significantly increased shoot length, shoot dry biomass, and root dry biomass of 120-day-old seedlings over the noninoculated control. The beneficial effects of 4 selected strains, namely Enterobacter hormaechei RCE-1, Enterobacter asburiae RCE-2, Enterobacter ludwigii RCE-5, and Klebsiella pneumoniae RCE-7, on growth of the seedlings were visible up to 1 year after their transfer to 8 kg capacity pots. These strains were superior both in terms of in-vitro-assayed PGP attributes and of their beneficial effect in low phosphorus soil and, thus, may be promising bioinoculants for promoting early emergence and growth of MO seedlings.

  3. 短侧枝挂果核桃优良品种选择%Selection of Superior Juglans sigillata Varieties Fruiting on Short Lateral Branches

    Institute of Scientific and Technical Information of China (English)

    苏为耿; 陆斌; 刘金凤; 赵平

    2012-01-01

    针对云南核桃产业发展中存在的品种混杂,良莠不齐,丰产性能差等问题,开展了核桃(Juglanssig—illata)优良品种的选育工作。经过对核桃各品种的挂果情况的调查研究和品质分析,选出龙佳核桃、宁香核桃2个良种。%Because of the mixed varieties, uneven qualities and poor production in the development of walnut industry in Yunnan, the selection of superior Juglans sigillata varieties was done. According to investigation and quality analysis on fruiting of different Juglans sigillata varieties, Longjia walnut and Ningxiang walnut were selected.

  4. Metal binding affinity and selectivity in metalloproteins: insights from computational studies.

    Science.gov (United States)

    Dudev, Todor; Lim, Carmay

    2008-01-01

    This review highlights insights gained from computational studies on protein-metal recognition. We systematically dissect the various factors governing metal binding affinity and selectivity in proteins starting from (a) the intrinsic properties of the metal and neighboring metal cations (if present), to (b) the primary coordination sphere, (c) the second coordination shell, (d) the protein matrix, (e) the bulk solvent, and (f) competing non-protein ligands from the surrounding biological environment. The results herein reveal the fundamental principles and the molecular bases underlying protein-metal recognition, which serve as a guide to engineer novel metalloproteins with programmed properties.

  5. Present status and future outlook of selective metallization for electronics industry by laser irradiation to metal nanoparticles

    Science.gov (United States)

    Watanabe, Akira

    2015-03-01

    Recently an alternative to conventional methods based on vacuum processes such as evaporation or sputtering is desired to reduce the energy consumption and the environmental impact. Printed electronics has been developed as a one of the candidates, which is based on wet processes using soluble functional materials such as organic semiconductors, inorganic nanomaterials, organic-inorganic hybrids, and so on. Although inkjet printing has been studied widely as a core technology of printed electronics, the limitation of resolution is around 20 micrometer. The combination of the inkjet printing with other selective metallization process is necessary because the resolution of several micrometers is required in some optical and electrical devices. The laser processing has emerged as an attractive technique in microelectronics because of the fascinating features such as high resolution, high degree of flexibility to control the resolution and size of the micro-patterns, high speed, and a little environmental pollution. In this paper, the present status and future outlook of selective metallization for interconnection and the formation of transparent conductive film based on the laser processing using metal nanoparticles were reported. The laser beam irradiation to metal nanoparticles causes the fast and efficient sintering by plasmon resonance of metal nanoparticle, where the absorbed energy is confined in a nanoparticle and the nanoparticle acts as a nano-heater. The laser irradiation to metal nanoparticles was applied to the laser direct writing of metal wiring and micropatterns using silver and copper nanoparticles.

  6. Heavy metal driven co-selection of antibiotic resistance in soil and water bodies impacted by agriculture and aquaculture

    OpenAIRE

    Seiler, Claudia; Berendonk, Thomas U

    2012-01-01

    The use of antibiotic agents as growth promoters was banned in animal husbandry to prevent the selection and spread of antibiotic resistance. However, in addition to antibiotic agents, heavy metals used in animal farming and aquaculture might promote the spread of antibiotic resistance via co-selection. To investigate which heavy metals are likely to co-select for antibiotic resistance in soil and water, the available data on heavy metal pollution, heavy metal toxicity, heavy metal tolerance,...

  7. Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Kim S.-Y.

    2015-06-01

    Full Text Available Porous metallic materials have been widely used in many fields including aerospace, atomic energy, electro chemistry and environmental protection. Their unique structures make them very useful as lightweight structural materials, fluid filters, porous electrodes and catalyst supports. In this study, we fabricated Ni-based porous metallic glasses having uniformly dispersed micro meter pores by the sequential processes of ball-milling and chemical dissolution method. We investigated the application of our porous metal supported for Pt catalyst. The oxidation test was performed in an atmosphere of 1% CO and 3% O2. Microstructure observation was performed by using a scanning electron microscope. Oxidation properties and BET (Brunauer, Emmett, and Teller were analyzed to understand porous structure developments. The results indicated that CO Oxidation reaction was dependent on the specific surface area.

  8. Fast selective metal deposition on polymers by using IR and excimer VUV photons

    Science.gov (United States)

    Esrom, Hilmar

    2000-12-01

    The major advantages of infra-red (IR) lamp induced decomposition of metal organic films for large-area deposition of metal films on substrate surfaces, local excimer laser ablation of thin metal films, and subsequent electroless metal plating were combined to develop a novel fast selective metallisation technique for thermally stable polymers. With the new method, metal structures with high edge quality on different types of polyimide (PI) foils can be produced easily. Without damaging the underlying PI substrate, the metal organic film (e.g. palladium acetate, PdAc) can be decomposed by infra-red irradiation in only about one second. The precise etching capability of ArF excimer laser ablation at λ=193 nm allows the IR-induced palladium (Pd) layers to be removed from the PI surface with one excimer laser pulse, selectively. The residual patterned Pd film on the PI surface then acts as an excellent catalyst for conventional electroless copper plating.

  9. Metal-Organic Frameworks for Highly Selective Separations

    Energy Technology Data Exchange (ETDEWEB)

    Omar M. Yaghi

    2009-09-28

    This grant was focused on the study of metal-organic frameworks with these specific objectives. (1) To examine the use of MOFs with well-defined open metal sites for binding of gases and small organics. (2) To develop a strategy for producing MOFs that combine large pore size with high surface area for their use in gas adsorption and separation of polycyclic organic compounds. (3) To functionalize MOFs for the storage of inert gases such as methane. A brief outline of our progress towards these objectives is presented here as it forms part of the basis for the ideas to be developed under the present proposal.

  10. Non-porous metal membranes for selective separation of hydrogen from gas mixtures at higher temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Winkelmann, U.; Schulten, R.; Weirich, W.; Kuegler, B.; Luecke, L.; Oertel, M.; Pietsch, M.; Schmitz, J.

    1986-10-01

    Materials for selective separation of hydrogen from gas mixtures by means of a metal membrane must have high permeability for dissolved oxygen, catalytically active surfaces, and mechanical stability in a hydrogen atmosphere. The transition metals Nb, Ta, and V have high hydrogen permeability, but they must be coated with a catalytically active Pd alloy in order to permit hydrogen permeation. The alloy TiNi can be used without a noble metal coating.

  11. Enhanced selective metal adsorption on optimised agroforestry waste mixtures.

    Science.gov (United States)

    Rosales, Emilio; Ferreira, Laura; Sanromán, M Ángeles; Tavares, Teresa; Pazos, Marta

    2015-04-01

    The aim of this work is to ascertain the potentials of different agroforestry wastes to be used as biosorbents in the removal of a mixture of heavy metals. Fern (FE), rice husk (RI) and oak leaves (OA) presented the best removal percentages for Cu(II) and Ni(II), Mn(II) and Zn(II) and Cr(VI), respectively. The performance of a mixture of these three biosorbents was evaluated, and an improvement of 10% in the overall removal was obtained (19.25mg/g). The optimum mixture proportions were determined using simplex-centroid mixture design method (FE:OA:RI=50:13.7:36.3). The adsorption kinetics and isotherms of the optimised mixture were fit by the pseudo-first order kinetic model and Langmuir isotherm. The adsorption mechanism was studied, and the effects of the carboxylic, hydroxyl and phenolic groups on metal-biomass binding were demonstrated. Finally, the recoveries of the metals using biomass were investigated, and cationic metal recoveries of 100% were achieved when acidic solutions were used.

  12. Directed Selection of Biochars for Amending Metal Contaminated Mine Soils

    Science.gov (United States)

    Approximately 500,000 abandoned mines across the U.S. pose a considerable, pervasive risk to human health and the environment. World-wide the problem is even larger. Lime, organic matter, biosolids and other amendments have been used to decrease metal bioavailability in contami...

  13. Optimal selection of biochars for remediating metals contaminated mine soils

    Science.gov (United States)

    Approximately 500,000 abandoned mines across the U.S. pose a considerable, pervasive risk to human health and the environment due to possible exposure to the residuals of heavy metal extraction. Historically, a variety of chemical and biological methods have been used to reduce ...

  14. Recycling of Metals and Materials: A Selected Bibliography.

    Science.gov (United States)

    Seidman, Ruth K., Comp.; Castrow, Lee, Comp.

    Recycling of metals and materials has as its purpose the easing of two major environmental crises. First, we re-utilize scarce and non-renewable resources. Second, solid waste disposal problems can be alleviated. Industry has long been concerned with reclaiming its own waste products, and is now beginning to respond to the need for dealing with…

  15. Selective micro metallization of polymers for biomedical and medical application

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

    Integration of micro/nano metallic structures in polymer devices is a broad multi-disciplinary research field, consisting of various combinations of mechanical, chemical and physical fabrication methods. Some of these combinations have been known for years and other combinations or methods are ve...

  16. Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wen [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Banerjee, Debasis [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Liu, Jian [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Schaef, Herbert T. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Crum, Jarrod V. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Fernandez, Carlos A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Kukkadapu, Ravi K. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nie, Zimin [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nune, Satish K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Motkuri, Radha K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Chapman, Karena W. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Hayes, James C. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Silvers, Kurt L. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Krishna, Rajamani [Van' t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904 1098 XH Amsterdam The Netherlands; McGrail, B. Peter [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Liu, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Thallapally, Praveen K. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-03-08

    A redox-active metal-organic composite material shows improved and selective O-2 adsorption over N-2 with respect to individual components (MIL-101 and ferrocene). The O-2 sensitivity of the composite material arises due to the formation of maghemite nanoparticles with the pore of the metal-organic framework material.

  17. A highly stable dynamic fluorescent metal-organic framework for selective sensing of nitroaromatic explosives.

    Science.gov (United States)

    Gong, Yun-Nan; Jiang, Long; Lu, Tong-Bu

    2013-12-07

    A dynamic fluorescent metal-organic framework has been constructed using triphenylene-2,6,10-tricarboxylate and Tb(3+) as building blocks, which exhibits guest-responsive structural dynamism and selective sensing of nitroaromatic explosives.

  18. Selected Metals in Canned Fish Consumed in Iran

    Directory of Open Access Journals (Sweden)

    Seyed Vali Hosseini

    2014-12-01

    Full Text Available Background: The presence of heavy metals in the environment could constitute a hazard to food security and public health. These can be accumulated in aquatic animals such as fish. Canned fish is consumed regularly in many countries. In this study, the levels of heavy metals Cu, Ni, Fe and Cr were evaluated in commercial canned fish products that are commonly consumed in Iran. The canned fish studied were longtail tuna, Kawakawa, Kilka and yellowfin tuna. Methods: Samples of four popular brands of canned fish in the Iranian market (yellowfin tuna, common Kilka, Kawakawa and longtail tuna were analyzed for levels of Cu, Ni, Fe and Cr after wet digestion with acids using graphite furnace atomic absorption spectrophotometry. Results: The mean concentrations for the metals in the different brands were: For Cu: 0.91, 0.73, 1.18 and 0.84 μg g-1 for brands A, B, C and D respectively. For Ni: 0.37, 0.19, 0.14 and 0.18 μg g-1 for brands A, B, C and D respectively; For Fe: 45.9, 34.0, 77.53 and 61.3 μg g-1 for brands A, B, C and D respectively. For Cr: 2.57, 3.24, 3.16 and 1.65 μg g-1 for brands A, B, C and D respectively. Significant differences were observed in the heavy metal levels between all of the different brands of canned fish evaluated in this study. Conclusion: The metal concentrations for the varieties of canned fishes were generally within the FAO/WHO, U.S. FDA and U.S. EPA recommended limits for fish except for Iron for which all different Brands exceeded the limit.

  19. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, Richard A.

    2012-06-04

    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  20. Tuning the chemical selectivity of SWNT-FETs for detection of heavy-metal ions.

    Science.gov (United States)

    Forzani, Erica S; Li, Xiulan; Zhang, Peiming; Tao, Nongjian; Zhang, Ruth; Amlani, Islamshah; Tsui, Raymond; Nagahara, Larry A

    2006-11-01

    A method to functionalize single-walled carbon nanotubes (SWNTs) in a field-effect transistor (FET) device for the selective detection of heavy-metal ions is presented. In this method, peptide-modified polymers were electrochemically deposited onto SWNTs and the selective detection of metal ions was demonstrated by choosing appropriate peptide sequences. The signal transduction mechanism of the peptide-modified SWNT-FETs has also been studied.

  1. Presence of selected chemicals of emerging concern in water and bottom sediment from the St. Louis River, St. Louis Bay, and Superior Bay, Minnesota and Wisconsin, 2010

    Science.gov (United States)

    Christensen, Victoria G.; Lee, Kathy E.; Kieta, Kristen A.; Elliott, Sarah M.

    2012-01-01

    The St. Louis Bay of Lake Superior receives substantial urban runoff, wastewater treatment plant effluent, and industrial effluent. In 1987, the International Joint Commission designated the St. Louis Bay portion of the lower St. Louis River as one of the Great Lakes Areas of Concern. Concerns exist about the potential effects of chemicals of emerging concern on aquatic biota because many of these chemicals, including endocrine active chemicals, have been shown to affect the endocrine systems of fish. To determine the occurrence of chemicals of emerging concern in the St. Louis River, the St. Louis Bay, and Superior Bay, the U.S. Geological Survey in cooperation with the Minnesota Pollution Control Agency and the Wisconsin Department of Natural Resources collected water and bottom-sediment samples from 40 sites from August through October 2010. The objectives of this study were to (1) identify the extent to which chemicals of emerging concern, including pharmaceuticals, hormones, and other organic chemicals, occur in the St. Louis River, St. Louis Bay, and Superior Bay, and (2) identify the extent to which the chemicals may have accumulated in bottom sediment of the study area. Samples were analyzed for selected wastewater indicators, hormones, sterols, bisphenol A, and human-health pharmaceuticals. During this study, 33 of 89 chemicals of emerging concern were detected among all water samples collected and 56 of 104 chemicals of emerging concern were detected in bottom-sediment samples. The chemical N,N-diethyl-meta-toluamide (DEET) was the most commonly detected chemical in water samples and 2,6-dimethylnaphthalene was the most commonly detected chemical in bottom-sediment samples. In general, chemicals of emerging concern were detected at a higher frequency in bottom-sediment samples than in water samples. Estrone (a steroid hormone) and hexahydrohexamethyl cyclopentabensopyran (a synthetic fragrance) were the most commonly detected endocrine active chemicals in

  2. Superior catalysts for selective catalytic reduction of nitric oxide. Final technical report, October 1, 1993--September 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R.T.; Li, W.B.; Chen, J.P.; Hausladen, M.C.; Cheng, L.S.; Kikkinides, E.S.

    1995-12-31

    The most advanced and proven technology for NO{sub x} control for stationary sources is Selective Catalytic Reduction (SCR). In SCR, NO{sub x} is reduced by NH{sub 3} to N{sub 2} and H{sub 2}O. The commercial catalysts are based on V{sub 2}O{sub 5}/TiO{sub 2}, and the vanadium-based catalysts are patented by the Japanese (Mitsubishi). However, there are three main advantages for the vanadium-based SCR catalyst: (a) a tendency to be poisoned in the flue gas; (b) oxidation of SO{sub 2} to SO{sub 3} by V{sub 2}O{sub 5}, this is a particularly severe problem due to the higher sulfur content of American coals compared with coals used in Japan (from Australia) and in Europe; (c) environmental problems involved in the disposal of the spent catalyst (due to the toxicity of vanadium). In order to overcome these problems, in addition to the undesirable dominance by the Japanese patent position, the authors have studied in this project a new type of catalyst for the SCR reaction; namely, pillared clays, which have adjustable, unique structures and acidity. Three types of catalysts were developed and tested for this reaction, i.e. Fe{sub 2}O{sub 3}-pillared clays, delaminated Fe{sub 2}O{sub 3}-pillared clays, and ion-exchanged pillared clays. The project was divided into sixteen tasks, and will be reported as such.

  3. Advances in Thermal Modeling of Selective Laser Sintering of Metal Powders

    CERN Document Server

    Xiao, Bin

    2016-01-01

    Selective laser sintering (SLS) of single component metal powders is a rapid prototyping technology in which a high-energy laser beam scans, melts, shrinks and consolidates metal powders with single component. For better understanding physical mechanisms during laser sintering of single-component metal particles, a temperature transforming model with the consideration of shrinkage and convective flows is introduced to analyze the thermal/fluid behaviors in selective laser sintering of single powder layer. The model is also applied to investigate the sintering of powders on top of existing sintered layers under single- multiple-line scanning manners according to the practical manufacturing processes.

  4. Development of Experimental Setup of Metal Rapid Prototyping Machine using Selective Laser Sintering Technique

    Science.gov (United States)

    Patil, S. N.; Mulay, A. V.; Ahuja, B. B.

    2016-08-01

    Unlike in the traditional manufacturing processes, additive manufacturing as rapid prototyping, allows designers to produce parts that were previously considered too complex to make economically. The shift is taking place from plastic prototype to fully functional metallic parts by direct deposition of metallic powders as produced parts can be directly used for desired purpose. This work is directed towards the development of experimental setup of metal rapid prototyping machine using selective laser sintering and studies the various parameters, which plays important role in the metal rapid prototyping using SLS technique. The machine structure in mainly divided into three main categories namely, (1) Z-movement of bed and table, (2) X-Y movement arrangement for LASER movements and (3) feeder mechanism. Z-movement of bed is controlled by using lead screw, bevel gear pair and stepper motor, which will maintain the accuracy of layer thickness. X-Y movements are controlled using timing belt and stepper motors for precise movements of LASER source. Feeder mechanism is then developed to control uniformity of layer thickness metal powder. Simultaneously, the study is carried out for selection of material. Various types of metal powders can be used for metal RP as Single metal powder, mixture of two metals powder, and combination of metal and polymer powder. Conclusion leads to use of mixture of two metals powder to minimize the problems such as, balling effect and porosity. Developed System can be validated by conducting various experiments on manufactured part to check mechanical and metallurgical properties. After studying the results of these experiments, various process parameters as LASER properties (as power, speed etc.), and material properties (as grain size and structure etc.) will be optimized. This work is mainly focused on the design and development of cost effective experimental setup of metal rapid prototyping using SLS technique which will gives the feel of

  5. Spin-on metal oxide materials with high etch selectivity and wet strippability

    Science.gov (United States)

    Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

    2016-03-01

    Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

  6. Comparative Study of Heavy Metals in Soil and Selected Medicinal Plants

    Directory of Open Access Journals (Sweden)

    Afzal Shah

    2013-01-01

    Full Text Available Essential and nonessential heavy metals like iron (Fe, nickel (Ni, manganese (Mn, zinc (Zn, copper (Cu, cadmium (Cd, chromium (Cr, and lead (Pb were analyzed in four selected medicinal plants such as Capparis spinosa, Peganum harmala, Rhazya stricta, and Tamarix articulata by flame atomic absorption spectrophotometer (FAAS. These medicinal plants are extensively used as traditional medicine for treatment of various ailments by local physicians in the area from where these plants were collected. The concentration level of heavy metals in the selected plants was found in the decreasing order as Fe > Zn > Mn > Cu > Ni > Cr > Cd > Pb. The results revealed that the selected medicinal plants accumulate these elements at different concentrations. Monitoring such medicinal plants for heavy metals concentration is of great importance for physicians, health planners, health care professionals, and policymakers in protecting the public from the adverse effects of these heavy metals.

  7. Hydroponical estimation of interactions among selected heavy metals accumulated by Salix viminalis in phytoremediation process.

    Science.gov (United States)

    Mleczek, Mirosław; Magdziak, Zuzanna; Kaczmarek, Zygmunt; Golinski, Piotr

    2010-09-01

    Determination of interactions between selected heavy metals (Cd, Co, Cr, Cu, Ni, Pb and Zn) in their phytoremediation by one-year-old cuttings of Salix viminalis 'Cannabina' was the purpose of this work. The achieved results indicate that Salix cuttings may successfully be used in phytoremediation of polluted soil and/or sewage not only with one metal at high concentrations but also in different combinations with the other metals. Under controlled conditions (the hydroponic experiment) new interactions were found as well as known data concerning interactions between-presented in the matrix-heavy metals, depending on whether their concentration and composition were confirmed. The results showed that the ratio of metal concentration can change the interaction intensity. The achieved results enable one to indirectly estimate the accumulation efficiency of dominating metals as well as accompanying ones at lower concentrations.

  8. Pyrometallurgical slags as a potential source of selected metals recovery

    Directory of Open Access Journals (Sweden)

    K. Nowińska

    2014-10-01

    Full Text Available Complex analysis of concentration and form of occurrence such metals as Zn, Pb, Fe and Cu in slags formed during a current zinc production in the Imperial Smelting Process (ISP is a possible basis for development of optimal recovery technology. For this purpose studies of slags from the current production of the Shaft Furnace Unit and of the Lead Refining of the “Miasteczko Śląskie” Zinc Smelting Plant were carried out. The studies results show that slags includes high concentrations of: Zn from 0,064 % to 1,680 %, Pb from 10,56 % to 50,71 %, Fe from 0,015 % to 2,576 %, Cu from 7,48 % to 64,95 %, and change in a broad range. This slags show significant heterogeneity, caused by intermetallic phases (Zn - Pb, Cu - Zn, Cu - Pb formed on the surface thereof. It is so possible that slag can be a potential source of this metals recovery.

  9. Metal selectivity by the virulence-associated yersiniabactin metallophore system

    Science.gov (United States)

    Koh, Eun-Ik; Hung, Chia S.; Parker, Kaveri S.; Crowley, Jan R.; Giblin, Daryl E.; Henderson, Jeffrey P.

    2016-01-01

    SUMMARY Uropathogenic Escherichia coli secrete siderophores during human infections. Although siderophores are classically defined by their ability to bind ferric ions, the virulence-associated siderophore yersiniabactin was recently found to bind divalent copper ions during urinary tract infections. Here we use a mass spectrometric approach to determine the extent of non-ferric metal interactions by yersiniabactin and its TonB-dependent outer membrane importer FyuA. In addition to copper, iron and gallium ions, yersiniabactin was also observed to form stable nickel, cobalt, and chromium ion complexes. In E. coli, copper(II) and all other non-ferric yersiniabactin complexes were imported by FyuA in a TonB-dependent manner. Among metal-yersiniabactin complexes, copper(II) yersiniabactin is predicted to be structurally distinctive and was the only complex not to competitively inhibit ferric yersiniabactin import. These results are consistent with yersiniabactin as part of a metallophore system able to prioritize ferric complex uptake in high copper environments. PMID:25824627

  10. Supramolecular control of selectivity in transition metal catalysis: Substrate preorganization & cofactor-steered catalysis

    NARCIS (Netherlands)

    Dydio, P.F.

    2013-01-01

    The selectivity displayed by transition metal catalysts is one of the key elements in catalysis, and various tools to control this by ligand modification have been reported. Some selectivity issues are, however, difficult to solve using the traditional methods. Therefore we have an interest in the

  11. Molecular recognition in homogeneous transition metal catalysis: a biomimetic strategy for high selectivity.

    Science.gov (United States)

    Das, Siddartha; Brudvig, Gary W; Crabtree, Robert H

    2008-01-28

    Traditional methods for selectivity control in homogeneous transition metal catalysis either employ steric effects in a binding pocket or chelate control. In a supramolecular strategy, encapsulation of the substrate can provide useful shape and size selectivity. A fully developed molecular recognition strategy involving hydrogen bonding or solvophobic forces has given almost completely regioselective functionalization of remote, unactivated C-H bonds.

  12. Selective anion exchange with nanogated isoreticular positive metal-organic frameworks.

    Science.gov (United States)

    Zhao, Xiang; Bu, Xianhui; Wu, Tao; Zheng, Shou-Tian; Wang, Le; Feng, Pingyun

    2013-01-01

    Crystalline porous materials, especially inorganic porous solids such as zeolites, usually have negative frameworks with extra-framework mobile cations and are widely used for cation exchange. It is highly desirable to develop new materials with positive frameworks for selective anion exchange and separation or storage and delivery. Recent advances in metal-organic framework synthesis have created new opportunities in this direction. Here we report the synthesis of a series of positive indium metal-organic frameworks and their utilization as a platform for the anion exchange-based separation process. This process is capable of size- or charge-selective ion-exchange of organic dyes and may form the basis for size-selective ion chromatography. Ion-exchange dynamics of a series of organic dyes and their selective encapsulation and release are also studied, highlighting the advantages of metal-organic framework compositions for designing host materials tailored for applications in anion separation and purification.

  13. Chelant extraction of heavy metals from contaminated soils using new selective EDTA derivatives.

    Science.gov (United States)

    Zhang, Tao; Liu, Jun-Min; Huang, Xiong-Fei; Xia, Bing; Su, Cheng-Yong; Luo, Guo-Fan; Xu, Yao-Wei; Wu, Ying-Xin; Mao, Zong-Wan; Qiu, Rong-Liang

    2013-11-15

    Soil washing is one of the few permanent treatment alternatives for removing metal contaminants. Ethylenediaminetetraacetic acid (EDTA) and its salts can substantially increase heavy metal removal from contaminated soils and have been extensively studied for soil washing. However, EDTA has a poor utilization ratio due to its low selectivity resulting from the competition between soil major cations and trace metal ions for chelation. The present study evaluated the potential for soil washing using EDTA and three of its derivatives: CDTA (trans-1,2-cyclohexanediaminetetraacetic acid), BDTA (benzyldiaminetetraacetic acid), and PDTA (phenyldiaminetetraacetic acid), which contain a cylcohexane ring, a benzyl group, and a phenyl group, respectively. Titration results showed that PDTA had the highest stability constants for Cu(2+) and Ni(2+) and the highest overall selectivity for trace metals over major cations. Equilibrium batch experiments were conducted to evaluate the efficacy of the EDTA derivatives at extracting Cu(2+), Zn(2+), Ni(2+), Pb(2+), Ca(2+), and Fe(3+) from a contaminated soil. At pH 7.0, PDTA extracted 1.5 times more Cu(2+) than did EDTA, but only 75% as much Ca(2+). Although CDTA was a strong chelator of heavy metal ions, its overall selectivity was lower and comparable to that of EDTA. BDTA was the least effective extractant because its stability constants with heavy metals were low. PDTA is potentially a practical washing agent for soils contaminated with trace metals.

  14. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides.

    Science.gov (United States)

    Hereijgers, Bart P C; Weckhuysen, Bert M

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with all studied catalyst materials, however, the selectivity for hydrogen increased from 15 % to 51 % when going from the unpromoted to a BaO-promoted catalyst. The formation of the undesired byproducts CO, methane, and dimethyl ether was considerably reduced as well. The observed trend in catalyst performance follows the trend in increasing basicity of the studied promoter elements, indicating a chemical effect of the promoter material. Superior catalytic performance, in terms of H(2) and CO selectivity, was obtained with a Au/La(2)O(3) catalyst. At 300 degrees C the hydrogen selectivity reached 80 % with only 2 % CO formation, and the catalyst displayed a stable performance over at least 24 h on-stream. Furthermore, the formation of CO was found to be independent of the oxygen concentration in the feed. The commercial lanthanum oxide used in this study had a low specific surface area, which led to the formation of relative large gold particles. Therefore, the catalytic activity could be enhanced by decreasing the gold particle size through deposition on lanthanum oxide supported on high-surface-area alumina.

  15. Superior performance of metal-organic frameworks over zeolites as solid acid catalysts in the Prins reaction: green synthesis of nopol.

    Science.gov (United States)

    Opanasenko, Maksym; Dhakshinamoorthy, Amarajothi; Hwang, Young Kyu; Chang, Jong-San; Garcia, Hermenegildo; Čejka, Jiří

    2013-05-01

    The catalytic performance of a set of metal-organic frameworks [CuBTC, FeBTC, MIL-100(Fe), MIL-100(Cr), ZIF-8, MIL-53(Al)] was investigated in the Prins condensation of β-pinene with formaldehyde and compared with the catalytic behavior of conventional aluminosilicate zeolites BEA and FAU and titanosilicate zeolite MFI (TS-1). The activity of the investigated metal-organic frameworks (MOFs) increased with the increasing concentration of accessible Lewis acid sites in the order ZIF-8zeolites BEA and FAU, which showed significantly lower selectivity to the target nopol than the MOFs. Its high activity, the preservation of its structure and active sites, and the possibility to use it in at least three catalytic cycles without loss of activity make MIL-100 (Fe) the best performing catalyst of the series for the Prins condensation of β-pinene and paraformaldehyde. Our report exemplifies the advantages of MOFs over zeolites as solid catalysts in liquid-phase reactions for the production of fine chemicals.

  16. Low concentrations of metal mixture exposures have adverse effects on selected biomarkers of Xenopus laevis tadpoles

    Energy Technology Data Exchange (ETDEWEB)

    Yologlu, Ertan, E-mail: ertanyologlu82@gmail.com [Adiyaman University, Faculty of Education, Department of Science Education, 02040 Adiyaman (Turkey); Ozmen, Murat [Inonu University, Laboratory of Environmental Toxicology, Department of Biology, Faculty of Arts & Science, 44280 Malatya (Turkey)

    2015-11-15

    Highlights: • Selected metal mixtures were evaluated for toxicity of safety limit concentrations. • Xenopus laevis tadpoles were used as model test organism. • Combinations of LC{sub 50} and LC{sub 50}/2 caused 100% lethality for some metals. • Metals did not change metallothionein levels in low concentrations. • Selected enzyme activities showed induction after low concentration exposures. - Abstract: Polluted ecosystems may contain mixtures of metals, such that the combinations of metals, even in low concentrations, may cause adverse effects. In the present study, we focused on toxic effects of mixtures of selected metals, the LC{sub 50} values, and also their safety limit in aquatic systems imposed by the European legislation using a model organism. Xenopus laevis tadpoles were used as test organisms. They were exposed to metals or their combinations due to 96-h LC{sub 50} values. Glutathione S-transferase (GST), glutathione reductase (GR), acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione peroxidase (GPx), and catalase (CAT) levels were evaluated. Metallothionein concentrations were also determined. The LC{sub 50}s for Cd, Pb, and Cu were calculated as 5.81 mg AI/L, 123.05 mg AI/L, and 0.85 mg AI/L, respectively. Low lethality ratios were observed with unary exposure of each metal in lower concentrations. Double or triple combinations of LC{sub 50} and LC{sub 50}/2 concentrations caused 100% lethality with Cd + Cu and Pb + Cd + Cu mixtures, while the Pb + Cu mixture also caused high lethal ratios. The selected enzyme activities were significantly affected by metals or mixtures, and dose-related effects were determined. The metallothionein levels generally increased as related to concentration in unary metals and mixtures. Acceptable limit values of unary metals and mixtures did not significantly change metallothionein levels. The results suggest that oxidative stress-related mechanisms are involved in the toxicity induced by selected

  17. Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

    Institute of Scientific and Technical Information of China (English)

    AN Hai-Long; LIU Yu-Zhi; ZHANG Su-Hua; ZHAN Yong; ZHANG Hai-Lin

    2008-01-01

    The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-311G basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.

  18. Method and apparatus for selective capture of gas phase analytes using metal .beta.-diketonate polymers

    Science.gov (United States)

    Harvey, Scott D [Kennewick, WA

    2011-06-21

    A process and sensor device are disclosed that employ metal .beta.-diketonate polymers to selectively capture gas-phase explosives and weaponized chemical agents in a sampling area or volume. The metal .beta.-diketonate polymers can be applied to surfaces in various analytical formats for detection of: improvised explosive devices, unexploded ordinance, munitions hidden in cargo holds, explosives, and chemical weapons in public areas.

  19. Extraction and Binding Efficiency of Calix[8]arene Derivative Toward Selected Transition Metals

    Directory of Open Access Journals (Sweden)

    Imdadullah Qureshi

    2008-12-01

    Full Text Available In this article we have explored the extraction efficiency as well as binding ability of calix[8]arene derivative (3 for selected transition metal ions (Co2+, Cd2+, Ni2+, Pb2+ and Cu2+. Picrate salt solutions of these metals were used in the liquid-liquid extraction experiments. It is apparent from the results that ligand 3 shows appreciable high extraction of transition metal cations, with the relative order Pb2+>Cu2+>Ni2+>Co2+>Cd2+ being observed. Highest extraction efficiency has been observed for Pb2+ and Cu2+ i.e. 95 and 91% respectively. The significant extraction and complexation ability for these metal ions may be attributed to the nature, size, structure and geometry of both ligand and metal ions.

  20. Selective Fluorination and Separation of Metals with NF3 for Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Richard A.; Barinaga, Charles J.; McNamara, Bruce K.; Schwantes, Jon M.; Ballou, Nathan E.

    2016-03-01

    We report recent progress on the development of a new methodology based on the generation of volatile metal fluorides through the use of nitrogen trifluoride (NF3), and the separation and measurement of these metal fluorides by electron ionization mass spectrometry. Though unreactive under ambient conditions, NF3 reacts selectively at specified temperatures with various metal-containing species to form volatile metal fluorides. Utilizing these species-dependent traits, elements of a sample may be sequentially produced and thus separated on-line. Metals were reacted inside a thermogravimetric analyzer, the gas outlet of which was directly coupled to a quadrupole mass spectrometer with an electron impact ionization source via a molecular leak valve. We present results of this project including the electron ionization mass spectrum of gaseous tellurium hexafluoride.

  1. Sound absorption of metallic sound absorbers fabricated via the selective laser melting process

    Science.gov (United States)

    Cheng, Li-Wei; Cheng, Chung-Wei; Chung, Kuo-Chun; Kam, Tai-Yan

    2017-01-01

    The sound absorption capability of metallic sound absorbers fabricated using the additive manufacturing (selective laser melting) method is investigated via both the experimental and theoretical approaches. The metallic sound absorption structures composed of periodic cubic cells were made of laser-melted Ti6Al4 V powder. The acoustic impedance equations with different frequency-independent and frequency-dependent end corrections factors are employed to calculate the theoretical sound absorption coefficients of the metallic sound absorption structures. The calculated sound absorption coefficients are in close agreement with the experimental results for the frequencies ranging from 2 to 13 kHz.

  2. Seeded-growth approach to selective metallization of microcontact-printed patterns.

    Science.gov (United States)

    Mewe, Agnes A; Kooij, E Stefan; Poelsema, Bene

    2006-06-20

    We report on a versatile nanocolloidal route to obtain large-scale conducting metal microstructures on a silicon oxide substrate. By using microcontact printing of an aminosilane, we create functionalized regions on the silicon oxide surface onto which gold nanoparticles selectively adhere. By using an established electroless, seeded-growth process, the individual, isolated gold nanocrystals are enlarged past the percolation threshold to form conducting metal structures. Quantitative characterization of metal coverage, thickness, and roughness has been performed with scanning electron microscopy and spectroscopic ellipsometry.

  3. Uniformly active phase loaded selective catalytic reduction catalysts (V{sub 2}O{sub 5}/TNTs) with superior alkaline resistance performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haiqiang; Wang, Penglu [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China); Chen, Xiongbo [South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655 (China); Wu, Zhongbiao, E-mail: zbwu@zju.edu.cn [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China)

    2017-02-15

    Highlights: • VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}. • Ion-exchange reaction occurs between VOSO{sub 4} and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO{sub 4}-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH{sub 4}VO{sub 3} and VOSO{sub 4}) were used to synthesize deNO{sub x} catalysts. The results showed that VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V{sup 5+}/V{sup 4+} redox cycles and superior oxygen mobility were achieved. Besides, VOSO{sub 4}-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V{sub 2}O{sub 5}/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

  4. Metal Abundances and Kinematics of Bright Metal-Poor Giants Selected from the LSE Survey Implications for the Metal-Weak Thick Disk

    CERN Document Server

    Beers, T C; Rossi, S; Chiba, M; Rhee, J; Fuhrmeister, B; Norris, J E; Von Hippel, T; Beers, Timothy C.; Drilling, John S.; Rossi, Silvia; Chiba, Masashi; Rhee, Jaehyon; Fuhrmeister, Birgit; Norris, John E.; Hippel, Ted von

    2002-01-01

    We report medium-resolution (1-2 A) spectroscopy and broadband (UBV) photometry for a sample of 39 bright stars (the majority of which are likely to be giants) selected as metal-deficient candidates from an objective-prism survey concentrating on Galactic latitudes below |b| = 30 deg, the LSE survey of Drilling & Bergeron. Although the primary purpose of the LSE survey was to select OB stars (hence the concentration on low latitudes), the small number of bright metal-deficient giant candidates noted during this survey provide interesting information on the metal-weak thick disk (MWTD) population. The kinematics of the LSE giants indicate the presence of a rapidly rotating population, even at quite low metallicity. We consider the distribution of orbital eccentricity of the LSE giants as a function of [Fe/H], and conclude that the local fraction (i.e., within 1 kpc from the Sun) of metal-poor stars that might be associated with the MWTD is on the order of 30%-40% at abundances below [Fe/H] = -1.0. Contrary...

  5. TiO2 embedded in carbon submicron-tablets: synthesis from a metal-organic framework precursor and application as a superior anode in lithium-ion batteries.

    Science.gov (United States)

    Wang, Peiyu; Lang, Junwei; Liu, Dongxia; Yan, Xingbin

    2015-07-21

    Rutile TiO2 embedded in carbon submicron-tablets (TiO2/C) with a "blueberry muffin" morphology was fabricated via a two-step pyrolysis from a metal-organic framework precursor. Such a unique structure of the TiO2/C submicron-tablets provides the ideal anode characteristics (high reversible capacity, superior rate capability and excellent long-term cycling stability) for fast rechargeable lithium ion batteries.

  6. Selective laser melting of metal micropowders with short-pulse laser

    Science.gov (United States)

    Wałpuski, B.

    2016-09-01

    Selective laser melting is a unique additive technique which can manufacture solid metal objects but it require expensive, high power lasers. The primary aim of this work was to check is it possible to carry out this process by using lower power and high energy pulse laser. The secondary goal was to examine the influence of main technological parameters of selective laser melting on the quality and the thickness of produced layer. The requirements of metal powder, which allowed to obtain a layer with microthickness, were developed.

  7. Magnetron sputtering cluster apparatus for formation and deposition of size-selected metal nanoparticles

    DEFF Research Database (Denmark)

    Hanif, Muhammad; Popok, Vladimir

    2015-01-01

    The experimental setup utilizing a DC magnetron sputtering source for production of metal clusters, their size (mass) selection and following deposition in high vacuum is described. The source is capable to form clusters of various metals, for example, copper, silver, gold etc. Cluster size...... selection is achieved using an electrostatic quadrupole mass selector. The deposited silver clusters are studied using atomic force microscopy. The height distributions show typical relative standard size deviation of 9-13% for given sizes in the range between 5-23 nm. Thus, the apparatus demonstrates good...

  8. Selection of a multidrug resistance plasmid by sublethal levels of antibiotics and heavy metals.

    Science.gov (United States)

    Gullberg, Erik; Albrecht, Lisa M; Karlsson, Christoffer; Sandegren, Linus; Andersson, Dan I

    2014-10-07

    How sublethal levels of antibiotics and heavy metals select for clinically important multidrug resistance plasmids is largely unknown. Carriage of plasmids generally confers substantial fitness costs, implying that for the plasmid-carrying bacteria to be maintained in the population, the plasmid cost needs to be balanced by a selective pressure conferred by, for example, antibiotics or heavy metals. We studied the effects of low levels of antibiotics and heavy metals on the selective maintenance of a 220-kbp extended-spectrum β-lactamase (ESBL) plasmid identified in a hospital outbreak of Klebsiella pneumoniae and Escherichia coli. The concentrations of antibiotics and heavy metals required to maintain plasmid-carrying bacteria, the minimal selective concentrations (MSCs), were in all cases below (almost up to 140-fold) the MIC of the plasmid-free susceptible bacteria. This finding indicates that the very low antibiotic and heavy metal levels found in polluted environments and in treated humans and animals might be sufficiently high to maintain multiresistance plasmids. When resistance genes were moved from the plasmid to the chromosome, the MSC decreased, showing that MSC for a specific resistance conditionally depends on genetic context. This finding suggests that a cost-free resistance could be maintained in a population by an infinitesimally low concentration of antibiotic. By studying the effect of combinations of several compounds, it was observed that for certain combinations of drugs each new compound added lowered the minimal selective concentration of the others. This combination effect could be a significant factor in the selection of multidrug resistance plasmids/bacterial clones in complex multidrug environments. Importance: Antibiotic resistance is in many pathogenic bacteria caused by genes that are carried on large conjugative plasmids. These plasmids typically contain multiple antibiotic resistance genes as well as genes that confer resistance to

  9. Effective and selective recovery of gold and palladium ions from metal wastewater using a sulfothermophilic red alga, Galdieria sulphuraria

    OpenAIRE

    2016-01-01

    The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cel...

  10. Implanted central venous catheter-related acute superior vena cava syndrome: management by metallic stent and endovascular repositioning of the catheter tip

    Energy Technology Data Exchange (ETDEWEB)

    Qanadli, S.D.; Mesurolle, B.; Sissakian, J.F.; Chagnon, S.; Lacombe, P. [Service de Radiologie, Hopital Ambroise Pare, 92 - Boulogne (France)

    2000-08-01

    We describe a case of a 49-year-old woman with stage-IIIB lung adenocarcinoma who experienced an acute superior vena cava syndrome related to an implanted central venous catheter without associated venous thrombosis. The catheter was surgically implanted for chemotherapy. Superior vena cava syndrome appeared after the procedure and was due to insertion of the catheter through a subclinical stenosis of the superior vena cava. Complete resolution of the patient's symptoms was obtained using stent placement and endovascular repositioning of the catheter tip. (orig.)

  11. Remediation and selective recovery of metals from acidic mine waters using novel modular bioreactors.

    Science.gov (United States)

    Hedrich, Sabrina; Johnson, D Barrie

    2014-10-21

    Mine waters are widely regarded as environmental pollutants, but are also potential sources of valuable metals. Water draining the Maurliden mine (Sweden) is highly acidic (pH 2.3) and rich in zinc (∼ 460 mg L(-1)) and iron (∼ 400 mg L(-1)), and contains smaller concentrations (0.3-49 mg L(-1)) of other transition metals and arsenic. We have developed novel techniques that promote the concurrent amelioration of acidic waste waters and selective recovery of metals, and have used these systems to treat synthetic Maurliden mine water in the laboratory. The two major metals present were removed via controlled biomineralization: zinc as ZnS in a sulfidogenic bioreactor, and iron as schwertmannite by microbial iron oxidation and precipitation of ferric iron. A small proportion (∼ 11%) of the schwertmannite produced was used to remove arsenic as the initial step in the process, and other chalcophilic metals (copper, cadmium and cobalt) were removed (as sulfides) in the stage 1 metal sulfide precipitation reactor. Results from this work have demonstrated that modular biomineralization units can be effective at processing complex mine waters and generating metal products that may be recycled. The economic and environmental benefits of using an integrated biological approach for treating metal-rich mine waters is discussed.

  12. 马尾松优良家系选择及遗传增益%A study on superior family selection and genetic gain of pinus massoniana

    Institute of Scientific and Technical Information of China (English)

    许鲁平

    2014-01-01

    以8 a 生马尾松子代林33个家系为对象,对其生长性状进行调查分析,结果表明,31号家系的平均胸径、树高和材积均显著高于其他家系,分别为11.74 cm、7.87 m、0.0398 m3.以平均胸径、树高大于群体5%以上,平均材积大于群体15%以上为优良家系标准,选择31和4号家系作为推荐品系.胸径和材积的家系遗传力较高,分别为0.31和0.30,材积的遗传增益最大,达到了0.64.%This paper analyzes the growth traits and genetic gains of 33 selected families in the 8-year-old pinus massoniana progeny forest. The results show that tree height,diameter at breast height,and volume of No. 31 are 11. 74 cm,7. 87 m,and 0. 039 8 m3 respectively,which is significantly higher than those of other families. It further set a standard that superior families should be higher than the population by 5%in the tree height and diameter at breast height and 15% in volume. Therefore,No. 31 and No. 4 are se-lected. The heritability of DBH and tree volume are 0. 31 and 0. 30,with the latter getting the highest ge-netic gain of 0. 64.

  13. Highly selective and sensitive detection of metal ions and nitroaromatic compounds by an anionic europium(iii) coordination polymer.

    Science.gov (United States)

    Feyisa Bogale, Raji; Ye, Junwei; Sun, Yuan; Sun, Tongxin; Zhang, Siqi; Rauf, Abdul; Hang, Cheng; Tian, Peng; Ning, Guiling

    2016-07-01

    A luminescent Eu(iii)-based coordination polymer, {[Eu(H2O)5(BTEC)][H(C5H6N2)]·3H2O} () has been synthesized under hydrothermal conditions using 1,2,4,5-benzenetetracarboxylic acid (H4BTEC) as a linker. Compound possesses an anionic zig-zag chain constructed from the BTEC ligands and [EuO4(H2O)5] nodes. The protonated 4-aminopyridine groups as guests are located between chains. exhibits the characteristic sharp emission bands of Eu(3+) at 578, 593, 615, 652 and 693 nm upon excitation at 290 nm. The strong emission of could be quenched effectively by trace amounts of Fe(3+) ions even in the presence of other metal ions including Al(3+), Ca(2+), Cd(2+), Co(2+), Cr(3+), Cu(2+), Fe(2+), K(+), Mg(2+), Mn(2+), Pd(2+) and Zn(2+). Similarly, also exhibits superior selectivity and sensitivity towards 4-nitrophenol (4-NP) compared with other competing interfering analytes, such as 2,4,6-trinitrophenol, 2,6-dinitrotolune, 4-nitrotoluene, nitrobenzene, 1,3-dinitrobenzene, o-xylene, nitromethane, nitropropane, phenol, 4-bromophenol and bromobenzene, through a fluorescence quenching mechanism. The possible fluorescence quenching mechanisms are discussed. Moreover, could be used as a visual fluorescent test paper for selectively detecting trace amounts of Fe(3+) and 4-NP.

  14. Fast growth increases the selective advantage of a mutation arising recurrently during evolution under metal limitation.

    Directory of Open Access Journals (Sweden)

    Hsin-Hung Chou

    2009-09-01

    Full Text Available Understanding the evolution of biological systems requires untangling the molecular mechanisms that connect genetic and environmental variations to their physiological consequences. Metal limitation across many environments, ranging from pathogens in the human body to phytoplankton in the oceans, imposes strong selection for improved metal acquisition systems. In this study, we uncovered the genetic and physiological basis of adaptation to metal limitation using experimental populations of Methylobacterium extorquens AM1 evolved in metal-deficient growth media. We identified a transposition mutation arising recurrently in 30 of 32 independent populations that utilized methanol as a carbon source, but not in any of the 8 that utilized only succinate. These parallel insertion events increased expression of a novel transporter system that enhanced cobalt uptake. Such ability ensured the production of vitamin B(12, a cobalt-containing cofactor, to sustain two vitamin B(12-dependent enzymatic reactions essential to methanol, but not succinate, metabolism. Interestingly, this mutation provided higher selective advantages under genetic backgrounds or incubation temperatures that permit faster growth, indicating growth-rate-dependent epistatic and genotype-by-environment interactions. Our results link beneficial mutations emerging in a metal-limiting environment to their physiological basis in carbon metabolism, suggest that certain molecular features may promote the emergence of parallel mutations, and indicate that the selective advantages of some mutations depend generically upon changes in growth rate that can stem from either genetic or environmental influences.

  15. Fast growth increases the selective advantage of a mutation arising recurrently during evolution under metal limitation.

    Science.gov (United States)

    Chou, Hsin-Hung; Berthet, Julia; Marx, Christopher J

    2009-09-01

    Understanding the evolution of biological systems requires untangling the molecular mechanisms that connect genetic and environmental variations to their physiological consequences. Metal limitation across many environments, ranging from pathogens in the human body to phytoplankton in the oceans, imposes strong selection for improved metal acquisition systems. In this study, we uncovered the genetic and physiological basis of adaptation to metal limitation using experimental populations of Methylobacterium extorquens AM1 evolved in metal-deficient growth media. We identified a transposition mutation arising recurrently in 30 of 32 independent populations that utilized methanol as a carbon source, but not in any of the 8 that utilized only succinate. These parallel insertion events increased expression of a novel transporter system that enhanced cobalt uptake. Such ability ensured the production of vitamin B(12), a cobalt-containing cofactor, to sustain two vitamin B(12)-dependent enzymatic reactions essential to methanol, but not succinate, metabolism. Interestingly, this mutation provided higher selective advantages under genetic backgrounds or incubation temperatures that permit faster growth, indicating growth-rate-dependent epistatic and genotype-by-environment interactions. Our results link beneficial mutations emerging in a metal-limiting environment to their physiological basis in carbon metabolism, suggest that certain molecular features may promote the emergence of parallel mutations, and indicate that the selective advantages of some mutations depend generically upon changes in growth rate that can stem from either genetic or environmental influences.

  16. A modular platform to develop peptoid-based selective fluorescent metal sensors.

    Science.gov (United States)

    Knight, Abigail S; Kulkarni, Rishikesh U; Zhou, Effie Y; Franke, Jenna M; Miller, Evan W; Francis, Matthew B

    2017-03-25

    Despite the reduction in industrial use of toxic heavy metals, there remain contaminated natural water sources across the world. Herein we present a modular platform for developing selective sensors for toxic metal ions using N-substituted glycine, or peptoid, oligomers coupled to a fluorophore. As a preliminary evaluation of this strategy, structures based on previously identified metal-binding peptoids were synthesized with terminal pyrene moieties. Both derivatives of this initial design demonstrated a turn-off response in the presence of various metal ions. A colorimetric screen was designed to identify a peptoid ligand that chelates Hg(ii). Multiple ligands were identified that were able to deplete Hg(ii) from a solution selectively in the presence of an excess of competing ions. The C-terminal fluoropeptoid derivatives demonstrated similar selectivity to their label-free counterparts. This strategy could be applied to develop sensors for many different metal ions of interest using a variety of fluorophores, leading to a panel of sensors for identifying various water source contaminants.

  17. IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLIC POWDER MATERIAL

    Institute of Scientific and Technical Information of China (English)

    Y.S.Shi; S.C.Chen; X.L.Lu; S.H.Huang

    2004-01-01

    How to directly fabricate metallic functional parts with selective laser sintering (SLS) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by use of SLS are analyzed. For the sake of solving the problems, a new idea of adding self-propagating high-temperature synthesis (SHS) material into metallic powder material to form new type of SLS metallic powder material is put forward. This powder material can release controllable amount of heat during its interaction with the laser beam energy to reduce the requirement to laser power during directly sintering metallic part, to prolong the time of metallic liquid phase existing, and to improve the intensity and accuracy of SLS part. For this reason, SHS material's interaction with the C02 laser beam energy is researched, which proves that CO2 laser beam energy may instantly ignite SHS reaction. On the basis of the above-mentioned researches, the effect of sintering the metal powder material mixing SHS material with CO2 laser is also researched,which shows: there is an optimal blending ratio of various material in the new metallic powder material. Under the optimal blending ratio and SLS process parameters, this new metallic powder material can indeed release amount of heat and SHS reaction may be controlled within the laser sintering. This research result makes it possible that the metallic part is directly sintered with small C02 laser (less than 50W), which may greatly reduce the volume, cost and running expenditure of SLS machine, be propitious to application.

  18. Selective Gold Recovery and Catalysis in a Highly Flexible Methionine-Decorated Metal-Organic Framework.

    Science.gov (United States)

    Mon, Marta; Ferrando-Soria, Jesús; Grancha, Thais; Fortea-Pérez, Francisco R; Gascon, Jorge; Leyva-Pérez, Antonio; Armentano, Donatella; Pardo, Emilio

    2016-06-29

    A novel chiral 3D bioMOF exhibiting functional channels with thio-alkyl chains derived from the natural amino acid l-methionine (1) has been rationally prepared. The well-known strong affinity of gold for sulfur derivatives, together with the extremely high flexibility of the thioether "arms" decorating the channels, account for a selective capture of gold(III) and gold(I) salts in the presence of other metal cations typically found in electronic wastes. The X-ray single-crystal structures of the different gold adsorbates Au(III)@1 and Au(I)@1 suggest that the selective metal capture occurs in a metal ion recognition process somehow mimicking what happens in biological systems and protein receptors. Both Au(III)@1 and Au(I)@1 display high activity as heterogeneous catalyst for the hydroalkoxylation of alkynes, further expanding the application of these novel hybrid materials.

  19. Site-selective electroless nickel plating on patterned thin films of macromolecular metal complexes.

    Science.gov (United States)

    Kimura, Mutsumi; Yamagiwa, Hiroki; Asakawa, Daisuke; Noguchi, Makoto; Kurashina, Tadashi; Fukawa, Tadashi; Shirai, Hirofusa

    2010-12-01

    We demonstrate a simple route to depositing nickel layer patterns using photocross-linked polymer thin films containing palladium catalysts, which can be used as adhesive interlayers for fabrication of nickel patterns on glass and plastic substrates. Electroless nickel patterns can be obtained in three steps: (i) the pattern formation of partially quaterized poly(vinyl pyridine) by UV irradiation, (ii) the formation of macromolecular metal complex with palladium, and (iii) the nickel metallization using electroless plating bath. Metallization is site-selective and allows for a high resolution. And the resulting nickel layered structure shows good adhesion with glass and plastic substrates. The direct patterning of metallic layers onto insulating substrates indicates a great potential for fabricating micro/nano devices.

  20. Electrofluidics fabricated by space-selective metallization in glass microfluidic structures using femtosecond laser direct writing.

    Science.gov (United States)

    Xu, Jian; Wu, Dong; Hanada, Yasutaka; Chen, Chi; Wu, Sizhu; Cheng, Ya; Sugioka, Koji; Midorikawa, Katsumi

    2013-12-07

    Space-selective metallization of the inside of glass microfluidic structures using femtosecond laser direct-write ablation followed by electroless plating is demonstrated. Femtosecond laser direct writing followed by thermal treatment and successive chemical etching allows us to fabricate three-dimensional microfluidic structures inside photosensitive glass. Then, femtosecond laser ablation followed by electroless metal plating enables flexible deposition of patterned metal films on desired locations of not only the top and bottom walls but also the sidewalls of fabricated microfluidic structures. A volume writing scheme for femtosecond laser irradiation inducing homogeneous ablation on the sidewalls of microfluidic structures is proposed for sidewall metallization. The developed technique is used to fabricate electrofluidics in which microelectric components are integrated into glass microchannels. The fabricated electrofluidics are applied to control the temperature of liquid samples in the microchannels for the enhancement of chemical reactions and to manipulate the movement of biological samples in the microscale space.

  1. Occurrence and distribution of selected metals in streams near Huntsville, Alabama

    Science.gov (United States)

    German, E.R.; Knight, Alfred L.

    1973-01-01

    Arsenic, cadmium, chromium, cobalt, lead, mercury, and zinc are widely distributed around Huntsville, Ala. However, concentrations of these metals in streamflow in the vicinity of the Huntsville municipal water intake during June, August, and September 1971 did not exceed the limits recommended for a public drinking water supply. The occurrence of these metals in general is related to man's activities. Information gained during this study suggests that cadmium and the other metals are associated with and transported with suspended sediment, bed material, and airborne dust particles. Lead and zinc were the most abundant of the selected metals in streamflow, bed material, and rainwater samples. The highest concentration of cadmium was detected downstream from an industrial park in the Flint River basin; rainwater samples also contained a relatively high level of cadmium.

  2. Metal-organic framework catalysts for selective cleavage of aryl-ether bonds

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Stavila, Vitalie

    2017-08-01

    The present invention relates to methods of employing a metal-organic framework (MOF) as a catalyst for cleaving chemical bonds. In particular instances, the MOF results in selective bond cleavage that results in hydrogenolyzis. Furthermore, the MOF catalyst can be reused in multiple cycles. Such MOF-based catalysts can be useful, e.g., to convert biomass components.

  3. Activity and selectivity control in reductive amination of butyraldehyde over noble metal catalysts.

    NARCIS (Netherlands)

    Bodis, E.; Lefferts, Leonardus; Muller, T.E.; Pestman, R.; Lercher, J.A.

    2005-01-01

    Approaches to control selectivity and activity in the catalytic reductive amination of butyraldehyde with ammonia over carbon supported noble metal catalysts (Ru, Rh, Pd, and Pt) were explored. Detailed analysis of the reaction network shows that the Schiff base N-[butylidene]butan-1-amine is the

  4. Direct selective oxygen-assisted acylation of amines driven by metallic silver surfaces: dimethylamine with formaldehyde.

    Science.gov (United States)

    Zhou, Ling; Freyschlag, Cassandra G; Xu, Bingjun; Friend, Cynthia M; Madix, Robert J

    2010-02-07

    Facile, direct acylation of dimethylamine with formaldehyde to N,N-dimethylformamide proceeds with a selectivity approaching 100% at low oxygen concentrations on metallic silver surfaces; the reaction proceeds via nucleophilic attack of adsorbed dimethylamide on formaldehyde with subsequent beta-H elimination from the adsorbed hemiaminal.

  5. Seeded-Growth Approach to Selective Metallization of Microcontact-Printed Patterns

    NARCIS (Netherlands)

    Mewe, Agnes A.; Kooij, E. Stefan; Poelsema, Bene

    2006-01-01

    We report on a versatile nanocolloidal route to obtain large-scale conducting metal microstructures on a silicon oxide substrate. By using microcontact printing of an aminosilane, we create functionalized regions on the silicon oxide surface onto which gold nanoparticles selectively adhere. By using

  6. Calibration of radiographs by a reference metal ball affects preoperative selection of implant size.

    Science.gov (United States)

    Schropp, Lars; Stavropoulos, Andreas; Gotfredsen, Erik; Wenzel, Ann

    2009-12-01

    The aim was to evaluate the impact of a reference ball for calibration of periapical and panoramic radiographs on preoperative selection of implant size for three implant systems. Presurgical digital radiographs (70 panoramic, 43 periapical) from 70 patients scheduled for single-tooth implant treatment, recorded with a metal ball placed in the edentulous area, were evaluated by three observers with the intent to select the appropriate implant size. Four reference marks corresponding to the margins of the metal ball were manually placed on the digital image by means of computer software. Additionally, an implant with proper dimensions for the respective site was outlined by manually placing four reference marks. The diameter of the metal ball and the unadjusted length and width of the implant were calculated. Implant size was adjusted according to a "standard" calibration method (SCM; magnification factor 1.25 in panoramic images and 1.05 in periapical images) and according to a reference ball calibration method (RCM; true magnification). Based on the unadjusted as well as the adjusted implant dimensions, the implant size was selected among those available in a given implant system. For periapical radiographs, when comparing SCM and RCM with unadjusted implant dimensions, implant size changed in 42% and 58%, respectively. When comparing SCM and RCM, implant size changed in 24%. For panoramic radiographs, comparing SCM and RCM changed implant size in 48%. The use of a reference metal ball for calibration of periapical and panoramic radiographs when selecting implant size during treatment planning might be advantageous.

  7. C- and N-Metalated Nitriles: The Relationship between Structure and Selectivity.

    Science.gov (United States)

    Yang, Xun; Fleming, Fraser F

    2017-09-20

    Metalated nitriles are exceptional nucleophiles capable of forging highly hindered stereocenters in cases where enolates are unreactive. The excellent nucleophilicity emanates from the powerful inductive stabilization of adjacent negative charge by the nitrile, which has a miniscule steric demand. Inductive stabilization is the key to understanding the reactivity of metalated nitriles because this permits a continuum of structures that range from N-metalated ketenimines to nitrile anions. Solution and solid-state analyses reveal two different metal coordination sites, the formally anionic carbon and the nitrile nitrogen, with the site of metalation depending intimately on the solvent, counterion, temperature, and ligands. The most commonly encountered structures, C- and N-metalated nitriles, have either sp(3) or sp(2) hybridization at the nucleophilic carbon, which essentially translates into two distinct organometallic species with similar but nonidentical stereoselectivity, regioselectivity, and reactivity preferences. The hybridization differences are particularly important in SNi displacements of cyclic nitriles because the orbital orientations create very precise trajectories that control the cyclization selectivity. Harnessing the orbital differences between C- and N-metalated nitriles allows selective cyclization to afford nitrile-containing cis- or trans-hydrindanes, decalins, or bicyclo[5.4.0]undecanes. Similar orbital constraints favor preferential SNi displacements with allylic electrophiles on sp(3) centers over sp(2) centers. The strategy permits stereoselective displacements on secondary centers to set contiguous tertiary and quaternary stereocenters or even contiguous vicinal quaternary centers. Stereoselective alkylations of acyclic nitriles are inherently more challenging because of the difficulty in creating steric differentiation in a dynamic system with rotatable bonds. However, judicious substituent placement of vicinal dimethyl groups and a

  8. pH triggered superior selective adsorption and separation of both cationic and anionic dyes and photocatalytic activity on a fully exfoliated titanate layer-natural polymer based nanocomposite.

    Science.gov (United States)

    Sarkar, Amit Kumar; Saha, Arka; Panda, Asit Baran; Pal, Sagar

    2015-11-18

    A fully exfoliated titanate layer-natural polymer amylopectin based nanocomposite, with pH responsive superior selective adsorption, separation of both cationic (MB: 599 mg g(-1) at pH 9) and anionic (MO: 558 mg g(-1) at pH 3) dyes and photodegradation properties, has been realized through simultaneous in situ layered titanate formation, exfoliation and polymerization.

  9. Reference site selection report for the advanced liquid metal reactor at the Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sivill, R.L.

    1990-03-01

    This Reference Site Selection Report was prepared by EG G, Idaho Inc., for General Electric (GE) to provide information for use by the Department of Energy (DOE) in selecting a Safety Test Site for an Advanced Liquid Metal Reactor. Similar Evaluation studies are planned to be conducted at other potential DOE sites. The Power Reactor Innovative Small Module (PRISM) Concept was developed for ALMR by GE. A ALMR Safety Test is planned to be performed on a DOE site to demonstrate features and meet Nuclear Regulatory Commission Requirements. This study considered possible locations at the Idaho National Engineering Laboratory that met the ALMR Prototype Site Selection Methodology and Criteria. Four sites were identified, after further evaluation one site was eliminated. Each of the remaining three sites satisfied the criteria and was graded. The results were relatively close. Thus concluding that the Idaho National Engineering Laboratory is a suitable location for an Advanced Liquid Metal Reactor Safety Test. 23 refs., 13 figs., 9 tabs.

  10. Low metal loading catalysts used for the selective hydrogenation of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Badano, Juan; Lederhos, Cecilia; Quiroga, Monica; L' Argentiere, Pablo [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Investigaciones en Catalisis y Petroquimica; Coloma-Pascual, Fernando [Universidad de Alicante (Spain). Facultad de Ciencias. Servicios Tecnicos de Investigacion

    2010-07-01

    A series of Group VIII metal catalysts was obtained for the semi-hydrogenation of styrene. Catalysts were characterized by Hydrogen Chemisorption, TPR and XPS. Palladium, rhodium and platinum low metal loading prepared catalysts presented high activity and selectivity (ca. 98%) during the semi-hydrogenation of styrene, being palladium the most active catalyst. The ruthenium catalyst also presented high selectivity (ca. 98%), but the lowest activity. For the palladium catalyst, the influence of the precursor salt and of the reduction temperature on the activity and selectivity were studied. The following activity series was obtained: PdN-423 > PdCl-673 > PdCl-373> PtCl-673 > RhCl-673 >> RuCl-673. As determined by XPS, differences in activity could be attributed, at least in part, to electronic effects (author)

  11. Producing metal parts with selective laser sintering/hot isostatic pressing

    Science.gov (United States)

    Das, Suman; Wohlert, Martin; Beaman, Joseph J.; Bourell, David L.

    1998-12-01

    Selective laser sintering/hot isostatic pressing is a hybrid direct laser fabrication method that combines the strengths of both processes. Selective laser sintering can produce complexly shaped metal components with an integral, gas-impermeable skin. These components can then be directly post-processed to full density by containerless hot isostatic pressing. The use of the hybrid fabrication method, envisioned as a rapid, low-cost replacement for conventional metal-can hot isostatic pressing, is currently being studied for alloy 625 and Ti-6Al-4V alloys. The micro-structure and mechanical properties of selective-laser-sintering processed and hot isostatically pressed post-processed material compare well with those of conventionally processed material.

  12. Synthesis and Selective Sensing Properties of rGO/Metal-Coloaded SnO2 Nanofibers

    Science.gov (United States)

    Kim, Jae-Hun; Zheng, Yifang; Mirzaei, Ali; Kim, Hyoun Woo; Kim, Sang Sub

    2017-02-01

    Ternary nanocomposites containing reduced graphene oxide (rGO) and metal (Pt or Pd)-coloaded SnO2 nanofibers (NFs) have been successfully synthesized by an electrospinning method. Transmission electron microscopy and field-emission scanning electron microscopy analyses revealed the NF morphology of the synthesized products. The gas sensing properties of the synthesized materials towards 1 ppm and 5 ppm C6H6, C7H8, and CO were tested, demonstrating enhanced sensing capability of the rGO/metal (Pt or Pd)-coloaded SnO2 NF sensor compared with that of pristine or rGO-loaded SnO2 NF sensors. Furthermore, selective sensing towards either C6H6 or C7H8 can be achieved by using Pd or Pt loading, respectively. The high specific surface area due to the existence of nanograins and p-rGO/n-SnO2 heterojunctions in the NFs, nanoheterojunctions between the noble metals and SnO2, as well as a sensitizing effect of Pt and Pd were responsible for the enhanced sensing response of the rGO/metal-coloaded SnO2 NF sensors. The obtained results demonstrate the promotional effect of coloading, as well as selectivity tuning by proper choice of a noble metal, being extendable to other gas sensing materials.

  13. Development a Cu-based Metal Powder for Selective Laser Micro Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Dai, C; Zhu, H H; Ke, L D; Lei, W J [Division of Laser Science and Technology, Wuhan National Laboratory for Optoelectronics, Institute of Optoelectronics Science and Engineering (China); Chen, B J, E-mail: chenbaijin@mail.hust.edu.cn [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. of China (China)

    2011-02-01

    A Cu-based metal powder which consists of Cu and Cu-P alloy for selective micro laser sintering has been developed based on the theoretical analysis of the characteristics of the laser micro sintering metal powder. The characteristics of the wetting, capillary force and viscosity have been considered. The preliminary experimental investigation on the selective laser micro sintering Cu-based metal powder has been performed. A 50 W CW Nd:YAG laser was employed to sinter the developed metal powder mixture. The sintering mechanism and the effect of the process parameters on the characteristics of the sintering samples have been preliminary investigated. The results show that the mechanism of laser micro sintering this developed metal powder is liquid-phase sintering and Cu-P alloy powder plays an effectively binder in the sintering process. The process parameter has significant effects on the characteristics of the sintering parts. From the SEM image, two different microstructures of samples with different scan spacing parameters were compared and a better binding effect was obtained at a parameter of 0.05mm scan spacing.

  14. Granulometric selectivity in Liza ramado and potential contamination resulting from heavy metal load in feeding areas

    Science.gov (United States)

    Pedro, Sílvia; Canastreiro, Vera; Caçador, Isabel; Pereira, Eduarda; Duarte, Armando C.; Raposo de Almeida, Pedro

    2008-11-01

    The stomach contents of thin-lipped grey mullets Liza ramado were analysed in terms of granulometric composition and compared to the sediment of potential feeding areas in the Tagus estuary. Total organic matter (TOM) content and heavy metal content were determined in the surface sediment of three areas and eight trace elements were quantified: Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. The three sampled areas did not differ in TOM; and the heavy metal content was below Effects Range-Low level for most elements. The mean observed concentrations were present in the following sequence: Zn > Pb > Cr > Cu ≈ Ni > Co > Cd > Hg. Stomach contents granulometric composition provided information about the feeding selectivity of the mullets. Sediment fractions with particle size between 20 and 50 μm are preferred, independently of the fishes' length. Smaller standard length (SL) fishes have a higher positive selection of fine grained sediments than those with a larger SL. Finer fractions usually have higher concentration of heavy metals, which makes younger specimens of the thin-lipped grey mullet potentially more exposed to heavy metal load in the estuary. Metal concentration was not independent from the sampling point, presenting higher values near the margins and the estuary tidal drainage system. This means that during the first period of each tidal cycle, the mullets will feed first on the most contaminated areas, as a consequence of their movement following the rising tide to feed on previously exposed areas.

  15. Polyurea-supported metal nanocatalysts: synthesis, characterization and application in selective hydrogenation of o-chloronitrobenzene.

    Science.gov (United States)

    Hao, Leiduan; Zhao, Yanfei; Yu, Bo; Zhang, Hongye; Xu, Huanjun; Xu, Jilei; Liu, Zhimin

    2014-06-15

    Polyurea (PU) spheres with size of 2-10 μm were derived through the polymerization of CO2 with 1,4-butanediamine, and characterized by FTIR spectroscopy, scanning electron microscopy and TG analysis. It was demonstrated that the PU spheres displayed flower-like morphology with the betel thickness around 30 nm, and they had high thermal stability. The resultant PU spheres were used to immobilize metal particles, and a series of PU-supported metal nanocatalysts including Pt/PU, Au/PU, Pd/PU were prepared via just mixing the metal precursors with the PU spheres in water, followed by the reduction of metal ions by NaBH4. Transmission electron microscopy examination indicated that the metal nanoparticles were distributed uniformly on the surface of the PU spheres with mean particle size less than 3.0 nm, and the Pt particles existed mainly in the form of metallic state as confirmed by the X-ray photoelectron spectroscopy analysis. The performance of the Pt/PU catalyst was tested in the catalytic hydrogenation of o-chloronitrobenzene, and a high selectivity of 99.5% toward o-chloroaniline at complete conversion of o-chloronitrobenzene was obtained at room temperature.

  16. Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hsing-Lung Lien

    2013-05-01

    Full Text Available Adsorption of precious metals in acidic aqueous solutions using thiourea modified magnetic magnetite nanoparticle (MNP-Tu was examined. The MNP-Tu was synthesized, characterized and examined as a reusable adsorbent for the recovery of precious metals. The adsorption kinetics were well fitted with pseudo second-order equation while the adsorption isotherms were fitted with both Langmuir and Freundlich equations. The maximum adsorption capacity of precious metals for MNP-Tu determined by Langmuir model was 43.34, 118.46 and 111.58 mg/g for Pt(IV, Au(III and Pd(II, respectively at pH 2 and 25 °C. MNP-Tu has high adsorption selectivity towards precious metals even in the presence of competing ions (Cu(II at high concentrations. In addition, the MNP-Tu can be regenerated using an aqueous solution containing 0.7 M thiourea and 2% HCl where precious metals can be recovered in a concentrated form. It was found that the MNP-Tu undergoing seven consecutive adsorption-desorption cycles still retained the original adsorption capacity of precious metals. A reductive adsorption resulting in the formation of elemental gold and palladium at the surface of MNP-Tu was observed.

  17. Compost as a source of microbial isolates for the bioremediation of heavy metals: in vitro selection.

    Science.gov (United States)

    Vargas-García, María del Carmen; López, María José; Suárez-Estrella, Francisca; Moreno, Joaquín

    2012-08-01

    Heavy metal pollution has become a major environmental concern nowadays and the bioremediation of polluted habitats is an increasingly popular strategy due to both its efficiency and safety. A screening and selection protocol based on different composting processes was designed in order to isolate heavy metal-resistant microorganisms. A collection of 51 microorganisms was obtained and most of them showed the capability to tolerate heavy metals in multi-polluted aqueous systems (Cd(II), Cr(VI), Ni, Pb, Zn(II)), as well as to remove them. The highest detoxification ratios were observed for Pb. Some of the isolates detoxifying more than a 90% of this metal, while the other metals were removed in a range between 20% and 60%. The best isolates (Graphium putredinis, Fusarium solani, Fusarium sp. and Penicillium chrysogenum) were further assayed in order to determine the predominant removal mechanism and the potential use of their dead biomass as a biosorbent. Intracellular accumulation was the prevalent mechanism for most isolates and metals, with the exception of Ni. In this case, the proportion removed by extracellular adsorption was similar or even higher than that removed by intracellular accumulation. Thus, the efficiency of living cells was higher than that of dead biomass except in the case of Ni.

  18. Data on heavy metals and selected anions in the Persian popular herbal distillates.

    Science.gov (United States)

    Keshtkar, Mozhgan; Dobaradaran, Sina; Soleimani, Farshid; Karbasdehi, Vahid Noroozi; Mohammadi, Mohammad Javad; Mirahmadi, Roghayeh; Ghasemi, Fatemeh Faraji

    2016-09-01

    In this data article, we determined the concentration levels of heavy metals including Pb, Co, Cd, Mn, Mg, Fe and Cu as well as selected anions including [Formula: see text] , [Formula: see text], [Formula: see text] and [Formula: see text] in the most used and popular herbal distillates in Iran. It is well known that heavy metals may pose a serious health hazard due to their bioaccumulation throughout the trophic chain ("Heavy metals (Cd, Cu, Ni and Pb) content in two fish species of Persian Gulf in Bushehr Port, Iran" (Dobaradaran et al., 2013) [1]; "Comparative investigation of heavy metal, trace, and macro element contents in commercially valuable fish species harvested off from the Persian Gulf" (Abadi et al., 2015) [2]) as well as some other environmental pollutions, "Assessment of sediment quality based on acid-volatile sulfide and simultaneously extracted metals in heavily industrialized area of Asaluyeh, Persian Gulf: concentrations, spatial distributions, and sediment bioavailability/toxicity" (Arfaeinia et al., 2016) [3]. The concentration levels of heavy metals and anions in herbal distillates samples were determined using flame atomic absorption spectrometry (FAAS, Varian AA240, Australia) and a spectrophotometer (M501 Single Beam Scanning UV/VIS, UK) respectively.

  19. Data on heavy metals and selected anions in the Persian popular herbal distillates

    Directory of Open Access Journals (Sweden)

    Mozhgan Keshtkar

    2016-09-01

    Full Text Available In this data article, we determined the concentration levels of heavy metals including Pb, Co, Cd, Mn, Mg, Fe and Cu as well as selected anions including NO3− , NO2−, PO4−3 and SO4−2 in the most used and popular herbal distillates in Iran. It is well known that heavy metals may pose a serious health hazard due to their bioaccumulation throughout the trophic chain (“Heavy metals (Cd, Cu, Ni and Pb content in two fish species of Persian Gulf in Bushehr Port, Iran” (Dobaradaran et al., 2013 [1]; “Comparative investigation of heavy metal, trace, and macro element contents in commercially valuable fish species harvested off from the Persian Gulf” (Abadi et al., 2015 [2] as well as some other environmental pollutions, “Assessment of sediment quality based on acid-volatile sulfide and simultaneously extracted metals in heavily industrialized area of Asaluyeh, Persian Gulf: concentrations, spatial distributions, and sediment bioavailability/toxicity” (Arfaeinia et al., 2016 [3]. The concentration levels of heavy metals and anions in herbal distillates samples were determined using flame atomic absorption spectrometry (FAAS, Varian AA240, Australia and a spectrophotometer (M501 Single Beam Scanning UV/VIS, UK respectively.

  20. An Exploration of the Metal Dependent Selectivity of a Metalloporphyrins Coated Quartz Microbalances Array

    Directory of Open Access Journals (Sweden)

    Alexandro Catini

    2016-10-01

    Full Text Available Several studies in the last two decades have demonstrated that metalloporphyrins coated quartz microbalances can be fruitfully used in many diverse applications, spanning from medical diagnosis to environmental control. This large versatility is due to the combination of the flexibility of metalloporphyrins molecular design with the independence of the quartz microbalance signal from the interaction mechanisms. The nature of the metal atom in the metalloporphyrins is often indicated as one of the most effective tools to design differently selective sensors. However, the properties of sensors are also strongly affected by the characteristics of the transducer. In this paper, the role of the metal atom is investigated studying the response, to various volatile compounds, of six quartz microbalance sensors that are based on the same porphyrin but with different metals. Results show that, since quartz microbalances (QMB transducers can sense all the interactions between porphyrin and volatile compounds, the metal ion does not completely determine the sensor behaviour. Rather, the sensors based on the same molecular ring but with different metal ions show a non-negligible common behaviour. However, even if limited, the different metals still confer peculiar properties to the sensors and might drive the sensor array identification of the pool of tested volatile compounds.

  1. An Exploration of the Metal Dependent Selectivity of a Metalloporphyrins Coated Quartz Microbalances Array

    Science.gov (United States)

    Catini, Alexandro; Kumar, Raj; Capuano, Rosamaria; Martinelli, Eugenio; Paolesse, Roberto; di Natale, Corrado

    2016-01-01

    Several studies in the last two decades have demonstrated that metalloporphyrins coated quartz microbalances can be fruitfully used in many diverse applications, spanning from medical diagnosis to environmental control. This large versatility is due to the combination of the flexibility of metalloporphyrins molecular design with the independence of the quartz microbalance signal from the interaction mechanisms. The nature of the metal atom in the metalloporphyrins is often indicated as one of the most effective tools to design differently selective sensors. However, the properties of sensors are also strongly affected by the characteristics of the transducer. In this paper, the role of the metal atom is investigated studying the response, to various volatile compounds, of six quartz microbalance sensors that are based on the same porphyrin but with different metals. Results show that, since quartz microbalances (QMB) transducers can sense all the interactions between porphyrin and volatile compounds, the metal ion does not completely determine the sensor behaviour. Rather, the sensors based on the same molecular ring but with different metal ions show a non negligible common behaviour. However, even if limited, the different metals still confer peculiar properties to the sensors and might drive the sensor array identification of the pool of tested volatile compounds. PMID:27782032

  2. Controlling damping and quality factors of silicon microcantilevers by selective metallization

    Science.gov (United States)

    Sosale, Guruprasad; Das, Kaushik; Fréchette, Luc; Vengallatore, Srikar

    2011-10-01

    Ceramic microresonators coated with relatively thin metallic films are widely used for sensing, scanning probe microscopy, signal processing and vibration energy harvesting. The metallization improves optical reflectivity and electrical conductivity, but invariably degrades the quality factor (Q) of resonance by increasing the amount of energy dissipated during vibration. Developing strategies for controlling damping due to metallization is vital for the design of high-performance microresonators. This paper presents a strategy based on the insight that dissipation is a function of the deformation experienced by the thin film during oscillation. Therefore, damping can be controlled by patterning the metal in regions of low strain. A simple analytical model is developed to quantify the change in damping as a function of selective metallization along the length of a microcantilever. The predictions of this model are in good agreement with measurements of damping in single-crystal silicon microcantilevers that are partially coated on one surface with 100 nm thick aluminum films. Crucially, damping due to clamping, support and viscous losses is minimized in these structures to enable a careful comparison of theory with experiments. Coating 20% of the length of the beam starting from the tip has no significant impact on damping in either the first or the second mode of vibration. In contrast, placing the same size of metallization at the root leads to considerable dissipation; in the first mode, the damping due to this patch is ~60% of that caused by a full coat.

  3. Selective removal of heavy metal ions by disulfide linked polymer networks

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Dongah [Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lyngby (Denmark); Lee, Joo Sung [Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141 (Korea, Republic of); Patel, Hasmukh A. [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Jakobsen, Mogens H. [Department of Micro and Nano technology, Technical University of Denmark, Ørsteds Plads, 345B, 2800 Kgs. Lyngby (Denmark); Hwang, Yuhoon [Department of Environmental Engineering, Seoul National University of Science and Technology, 232 Gongreung-ro, Nowon-gu, Seoul 01811 (Korea, Republic of); Yavuz, Cafer T. [Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141 (Korea, Republic of); Hansen, Hans Chr. Bruun [Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Thorvaldsensvej 40, 1871 Frederiksberg C (Denmark); Andersen, Henrik R., E-mail: henrik@ndersen.net [Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, 2800 Kgs. Lyngby (Denmark)

    2017-06-15

    Highlights: • Disulfide/thiol polymer networks are promising as sorbent for heavy metals. • Rapid sorption and high Langmuir affinity constant (a{sub L}) for stormwater treatment. • Selective sorption for copper, cadmium, and zinc in the presence of calcium. • Reusability likely due to structure stability of disulfide linked polymer networks. - Abstract: Heavy metal contaminated surface water is one of the oldest pollution problems, which is critical to ecosystems and human health. We devised disulfide linked polymer networks and employed as a sorbent for removing heavy metal ions from contaminated water. Although the polymer network material has a moderate surface area, it demonstrated cadmium removal efficiency equivalent to highly porous activated carbon while it showed 16 times faster sorption kinetics compared to activated carbon, owing to the high affinity of cadmium towards disulfide and thiol functionality in the polymer network. The metal sorption mechanism on polymer network was studied by sorption kinetics, effect of pH, and metal complexation. We observed that the metal ions–copper, cadmium, and zinc showed high binding affinity in polymer network, even in the presence of competing cations like calcium in water.

  4. Effective and selective recovery of precious metals by thiourea modified magnetic nanoparticles.

    Science.gov (United States)

    Lin, Tai-Lin; Lien, Hsing-Lung

    2013-05-08

    Adsorption of precious metals in acidic aqueous solutions using thiourea modified magnetic magnetite nanoparticle (MNP-Tu) was examined. The MNP-Tu was synthesized, characterized and examined as a reusable adsorbent for the recovery of precious metals. The adsorption kinetics were well fitted with pseudo second-order equation while the adsorption isotherms were fitted with both Langmuir and Freundlich equations. The maximum adsorption capacity of precious metals for MNP-Tu determined by Langmuir model was 43.34, 118.46 and 111.58 mg/g for Pt(IV), Au(III) and Pd(II), respectively at pH 2 and 25 °C. MNP-Tu has high adsorption selectivity towards precious metals even in the presence of competing ions (Cu(II)) at high concentrations. In addition, the MNP-Tu can be regenerated using an aqueous solution containing 0.7 M thiourea and 2% HCl where precious metals can be recovered in a concentrated form. It was found that the MNP-Tu undergoing seven consecutive adsorption-desorption cycles still retained the original adsorption capacity of precious metals. A reductive adsorption resulting in the formation of elemental gold and palladium at the surface of MNP-Tu was observed.

  5. Tapered dielectric structure in metal as a wavelength-selective surface plasmon polariton focuser

    Institute of Scientific and Technical Information of China (English)

    Zhang Yang; Zhao Qing; Liao Zhi-Min; Yu Da-Peng

    2009-01-01

    Symmetric tapered dielectric structures in metal have demonstrated applications such as the nanofocusing of surface plasmon polaxitons, as well as the waveguiding of V-channel polaxitons. Yet the fabrication of smooth-surfaced tapered structure remains an obstacle to most researchers. We have successfully developed a handy method to fabricate metal-sandwiched tapered nanostructures simply with electron beam lithography. Though these structures are slightly different from conventional symmetric V-shaped structures, systematic simulations show that similar functionality of surface plasmon polaxiton nanofocusing can still be achieved, When parameters are properly selected, wavelengthselective nanofocusing of surface plasmon polaritons can be obtained.

  6. [Content of selected metals in forest fruits depending on the harvest site].

    Science.gov (United States)

    Rusinek, Elzbieta; Sembratowicz, Iwona; Ognik, Katarzyna

    2008-01-01

    Contents of selected metals (Pb, Cd, Cu, Zn, Fe, Mn) were determined in samples of forest fruits: blueberry, raspberry and wild strawberry harvested in Lublin region from areas considered as potentially not exposed to pollution (Skierbieszów Landscape Park) and potentially polluted areas (Cement Factory Rejowiec S.A.). Analyzed fruits originating from stands more exposed to pollution were characterized by higher lead (except from raspberry) as well as other metals contents than those from Krasiczyn commune. Among studied fruits, blueberry was distinguished by the lowest contents of Pb, Zn, Fe, Mn, wild strawberry contained the highest levels of Pb, Zn and Mn. Cadmium content in analyzed plant materials was high.

  7. Antimony trifluoride-modified carbon paste electrode for electrochemical stripping analysis of selected heavy metals

    OpenAIRE

    Stočes, Matěj; Hočevar, Samo B.; Švancara, Ivan

    2011-01-01

    In this article, a new typ of non-mercury metal-based electrode, antimony trifluoridebulk- modified carbon paste electrode (SbF3-CPE) is for the first time reported and examined for electrochemical stripping analysis of selected heavy metal ions at their trace concentration level. In the role of bulk modifier and a source of antimony film generated in state nascenti, SbF3 in a content of 3% (w/w) in the carbon paste mixture was the ultimate choice. All important experimental parameters hav...

  8. Selective metallization of polymers using laser induced surface activation (LISA)—characterization and optimization of porous surface topography

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; De Grave, Arnaud

    2011-01-01

    Laser induced selective activation (LISA) is a molded interconnected devices technique for selective metallization of polymers. On the working piece, only the laser-machined area can be metalized in the subsequent plating. The principle of the technology is introduced. Surface analysis was perfor...

  9. Direct selective laser sintering of high performance metals: Machine design, process development and process control

    Science.gov (United States)

    Das, Suman

    1998-11-01

    This dissertation describes the development of an advanced manufacturing technology known as Direct Selective Laser Sintering (Direct SLS). Direct SLS is a laser based rapid manufacturing technology that enables production of functional, fully dense, metal and cermet components via the direct, layerwise consolidation of constituent powders. Specifically, this dissertation focuses on a new, hybrid net shape manufacturing technique known as Selective Laser Sintering/Hot Isostatic Pressing (SLS/HIP). The objective of research presented in this dissertation was to establish the fundamental machine technology and processing science to enable direct SLS fabrication of metal components composed of high performance, high temperature metals and alloys. Several processing requirements differentiate direct SLS of metals from SLS of polymers or polymer coated powders. Perhaps the most important distinguishing characteristic is the regime of high temperatures involved in direct SLS of metals. Biasing the temperature of the feedstock powder via radiant preheat prior to and during SLS processing was shown to be beneficial. Preheating the powder significantly influenced the flow and wetting characteristics of the melt. During this work, it was conclusively established that powder cleanliness is of paramount importance for successful layerwise consolidation of metal powders by direct SLS. Sequential trials were conducted to establish optimal bake-out and degas cycles under high vacuum. These cycles agreed well with established practices in the powder metallurgy industry. A study of some of the important transport mechanisms in direct SLS of metals was undertaken to obtain a fundamental understanding of the underlying process physics. This study not only provides an explanation of phenomena observed during SLS processing of a variety of metallic materials but also helps in developing selection schemes for those materials that are most amenable to direct SLS processing. The

  10. Compost as a source of microbial isolates for the bioremediation of heavy metals: In vitro selection

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Garcia, Maria del Carmen, E-mail: mcvargas@ual.es; Lopez, Maria Jose, E-mail: mllopez@ual.es; Suarez-Estrella, Francisca, E-mail: fsuarez@ual.es; Moreno, Joaquin, E-mail: jcasco@ual.es

    2012-08-01

    Heavy metal pollution has become a major environmental concern nowadays and the bioremediation of polluted habitats is an increasingly popular strategy due to both its efficiency and safety. A screening and selection protocol based on different composting processes was designed in order to isolate heavy metal-resistant microorganisms. A collection of 51 microorganisms was obtained and most of them showed the capability to tolerate heavy metals in multi-polluted aqueous systems (Cd(II), Cr(VI), Ni, Pb, Zn(II)), as well as to remove them. The highest detoxification ratios were observed for Pb. Some of the isolates detoxifying more than a 90% of this metal, while the other metals were removed in a range between 20% and 60%. The best isolates (Graphium putredinis, Fusarium solani, Fusarium sp. and Penicillium chrysogenum) were further assayed in order to determine the predominant removal mechanism and the potential use of their dead biomass as a biosorbent. Intracellular accumulation was the prevalent mechanism for most isolates and metals, with the exception of Ni. In this case, the proportion removed by extracellular adsorption was similar or even higher than that removed by intracellular accumulation. Thus, the efficiency of living cells was higher than that of dead biomass except in the case of Ni. - Highlights: Black-Right-Pointing-Pointer Composting is a good reservoir for the isolation of HM-resistant microorganisms. Black-Right-Pointing-Pointer Pb was the most removed heavy metal in multi-polluted aqueous systems. Black-Right-Pointing-Pointer Intracellular accumulation was the predominant mechanism for heavy metal removal. Black-Right-Pointing-Pointer Graphium putredinis, which detoxifies organic pollutants, was the most efficient isolate.

  11. High-throughput screening of metal-porphyrin-like graphenes for selective capture of carbon dioxide.

    Science.gov (United States)

    Bae, Hyeonhu; Park, Minwoo; Jang, Byungryul; Kang, Yura; Park, Jinwoo; Lee, Hosik; Chung, Haegeun; Chung, ChiHye; Hong, Suklyun; Kwon, Yongkyung; Yakobson, Boris I; Lee, Hoonkyung

    2016-02-23

    Nanostructured materials, such as zeolites and metal-organic frameworks, have been considered to capture CO2. However, their application has been limited largely because they exhibit poor selectivity for flue gases and low capture capacity under low pressures. We perform a high-throughput screening for selective CO2 capture from flue gases by using first principles thermodynamics. We find that elements with empty d orbitals selectively attract CO2 from gaseous mixtures under low CO2 pressures (~10(-3) bar) at 300 K and release it at ~450 K. CO2 binding to elements involves hybridization of the metal d orbitals with the CO2 π orbitals and CO2-transition metal complexes were observed in experiments. This result allows us to perform high-throughput screening to discover novel promising CO2 capture materials with empty d orbitals (e.g., Sc- or V-porphyrin-like graphene) and predict their capture performance under various conditions. Moreover, these findings provide physical insights into selective CO2 capture and open a new path to explore CO2 capture materials.

  12. UTSA-74: A MOF-74 Isomer with Two Accessible Binding Sites per Metal Center for Highly Selective Gas Separation.

    Science.gov (United States)

    Luo, Feng; Yan, Changsheng; Dang, Lilong; Krishna, Rajamani; Zhou, Wei; Wu, Hui; Dong, Xinglong; Han, Yu; Hu, Tong-Liang; O'Keeffe, Michael; Wang, Lingling; Luo, Mingbiao; Lin, Rui-Biao; Chen, Banglin

    2016-05-04

    A new metal-organic framework Zn2(H2O)(dobdc)·0.5(H2O) (UTSA-74, H4dobdc = 2,5-dioxido-1,4-benzenedicarboxylic acid), Zn-MOF-74/CPO-27-Zn isomer, has been synthesized and structurally characterized. It has a novel four coordinated fgl topology with one-dimensional channels of about 8.0 Å. Unlike metal sites in the well-established MOF-74 with a rod-packing structure in which each of them is in a five coordinate square pyramidal coordination geometry, there are two different Zn(2+) sites within the binuclear secondary building units in UTSA-74 in which one of them (Zn1) is in a tetrahedral while another (Zn2) in an octahedral coordination geometry. After activation, the two axial water molecules on Zn2 sites can be removed, generating UTSA-74a with two accessible gas binding sites per Zn2 ion. Accordingly, UTSA-74a takes up a moderately high and comparable amount of acetylene (145 cm(3)/cm(3)) to Zn-MOF-74. Interestingly, the accessible Zn(2+) sites in UTSA-74a are bridged by carbon dioxide molecules instead of being terminally bound in Zn-MOF-74, so UTSA-74a adsorbs a much smaller amount of carbon dioxide (90 cm(3)/cm(3)) than Zn-MOF-74 (146 cm(3)/cm(3)) at room temperature and 1 bar, leading to a superior MOF material for highly selective C2H2/CO2 separation. X-ray crystal structures, gas sorption isotherms, molecular modeling, and simulated and experimental breakthroughs comprehensively support this result.

  13. UTSA-74: A MOF-74 Isomer with Two Accessible Binding Sites per Metal Center for Highly Selective Gas Separation

    KAUST Repository

    Luo, Feng

    2016-04-26

    A new metal-organic framework Zn2(H2O)-(dobdc)·0.5(H2O) (UTSA-74, H4dobdc = 2,5-dioxido-1,4-benzenedicarboxylic acid), Zn-MOF-74/CPO-27-Zn isomer, has been synthesized and structurally characterized. It has a novel four coordinated fgl topology with one-dimensional channels of about 8.0 Å. Unlike metal sites in the wellestablished MOF-74 with a rod-packing structure in which each of them is in a five coordinate square pyramidal coordination geometry, there are two different Zn2+ sites within the binuclear secondary building units in UTSA-74 in which one of them (Zn1) is in a tetrahedral while another (Zn2) in an octahedral coordination geometry. After activation, the two axial water molecules on Zn2 sites can be removed, generating UTSA-74a with two accessible gas binding sites per Zn2 ion. Accordingly, UTSA-74a takes up a moderately high and comparable amount of acetylene (145 cm3/cm3) to Zn-MOF-74. Interestingly, the accessible Zn2+ sites in UTSA-74a are bridged by carbon dioxide molecules instead of being terminally bound in Zn-MOF-74, so UTSA-74a adsorbs a much smaller amount of carbon dioxide (90 cm3/cm3) than Zn-MOF-74 (146 cm3/cm3) at room temperature and 1 bar, leading to a superior MOF material for highly selective C2H2/CO2 separation. X-ray crystal structures, gas sorption isotherms, molecular modeling, and simulated and experimental breakthroughs comprehensively support this result. © 2016 American Chemical Society.

  14. Selective breakdown of metallic pathways in double-walled carbon nanotube networks.

    Science.gov (United States)

    Ng, Allen L; Sun, Yong; Powell, Lyndsey; Sun, Chuan-Fu; Chen, Chien-Fu; Lee, Cheng S; Wang, YuHuang

    2015-01-07

    Covalently functionalized, semiconducting double-walled carbon nanotubes exhibit remarkable properties and can outperform their single-walled carbon nanotube counterparts. In order to harness their potential for electronic applications, metallic double-walled carbon nanotubes must be separated from the semiconductors. However, the inner wall is inaccessible to current separation techniques which rely on the surface properties. Here, the first approach to address this challenge through electrical breakdown of metallic double-walled carbon nanotubes, both inner and outer walls, within networks of mixed electronic types is described. The intact semiconductors demonstrate a ∼62% retention of the ON-state conductance in thin film transistors in response to covalent functionalization. The selective elimination of the metallic pathways improves the ON/OFF ratio, by more than 360 times, to as high as 40 700, while simultaneously retaining high ON-state conductance.

  15. Selective nitrogen capture by porous hybrid materials containing accessible transition metal ion sites

    Science.gov (United States)

    Yoon, Ji Woong; Chang, Hyunju; Lee, Seung-Joon; Hwang, Young Kyu; Hong, Do-Young; Lee, Su-Kyung; Lee, Ji Sun; Jang, Seunghun; Yoon, Tae-Ung; Kwac, Kijeong; Jung, Yousung; Pillai, Renjith S.; Faucher, Florian; Vimont, Alexandre; Daturi, Marco; Férey, Gérard; Serre, Christian; Maurin, Guillaume; Bae, Youn-Sang; Chang, Jong-San

    2017-05-01

    Selective dinitrogen binding to transition metal ions mainly covers two strategic domains: biological nitrogen fixation catalysed by metalloenzyme nitrogenases, and adsorptive purification of natural gas and air. Many transition metal-dinitrogen complexes have been envisaged for biomimetic nitrogen fixation to produce ammonia. Inspired by this concept, here we report mesoporous metal-organic framework materials containing accessible Cr(III) sites, able to thermodynamically capture N2 over CH4 and O2. This fundamental study integrating advanced experimental and computational tools confirmed that the separation mechanism for both N2/CH4 and N2/O2 gas mixtures is driven by the presence of these unsaturated Cr(III) sites that allows a much stronger binding of N2 over the two other gases. Besides the potential breakthrough in adsorption-based technologies, this proof of concept could open new horizons to address several challenges in chemistry, including the design of heterogeneous biomimetic catalysts through nitrogen fixation.

  16. The impact of sewage sludge treatment on the content of selected heavy metals and their fractions.

    Science.gov (United States)

    Ignatowicz, Katarzyna

    2017-07-01

    The aim of the study was to assess the physicochemical properties of compost made of municipal sewage sludge from selected Municipal Sewage Treatment Plant. Content of basic macroelements and heavy metals (Zn, Cu, Cr, Cd, Ni, Pb, Hg, Mg, Ca, N, P, K, Na) and their fractions was determined by means of BCR method. Based on the analyzes, it was found that the content of heavy metals in compost did not exceed the limits set by natural land management of sewage sludge; the compost is very abundant in biogenic elements - nitrogen and phosphorus - and it can be also considered a significant source of calcium and magnesium. The analysis of results obtained from the three-stage chemical extraction revealed that deposits subjected to aerobic stabilization and composting accumulate metals (in descending sequence) in fractions III and II, i.e. fractions virtually inaccessible to the ecosystem in optimal conditions of use. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Speciation of heavy metals in garden soils. Evidences from selective and sequential chemical leaching

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Zhongqi; Lee, Leda; Dayan, Sara; Grinshtein, Michael [Brooklyn College of The City Univ. of New York, Brooklyn, NY (United States). Environmental Sciences Analytical Cnter; Shaw, Richard [USDA-NRCS NYC Soil Survey, Staten Island, NY (United States)

    2011-06-15

    Purpose: Gardening (especially food growing) in urban areas is becoming popular, but urban soils are often very contaminated for historical reasons. There is lack of sufficient information as to the bioavailability of soil heavy metals to plants and human in urban environments. This study examines the relative leachability of Cr, Ni, As, Cd, Zn, and Pb for soils with varying characteristics. The speciation and mobility of these metals can be qualitatively inferred from the leaching experiments. The goal is to use the data to shed some light on their bioavailability to plant and human, as well as the basis for soil remediation. Materials and methods: Selective and sequential chemical leaching methods were both used to evaluate the speciation of Cr, Ni, As, Cd, Zn, and Pb in soil samples collected from New York City residential and community gardens. The sequential leaching experiment followed a standard BCR four-step procedure, while selective leaching involved seven different chemical extractants. Results and discussion: The results from selective and sequential leaching methods are consistent. In general, very little of the heavy metals were found in the easily soluble or exchangeable fractions. Larger fractions of Cd and Zn can be leached out than other metals. Lead appears predominantly in the organic or carbonate fractions, of which {proportional_to} 30-60% is in the easily soluble organic fraction. Most As cannot be leached out by any of the extractants used, but it could have been complicated by the ineffective dissolution of oxides by ammonium hydroxylamine. Ni and Cr were mostly in the residual fractions but some released in the oxidizable fractions. Therefore, the leachability of metals follow the order Cd/Zn > Pb > Ni/Cr. Conclusions: Despite of the controversy and inaccuracy surrounding chemical leaching methods for the speciation of metals, chemical leaching data provide important, general, and easy-to-access information on the mobility of heavy metals

  18. Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, L. [Arizona State Univ., Tempe, AZ (United States); Boccard, Matthieu [Arizona State Univ., Tempe, AZ (United States); Holman, Zachary [Arizona State Univ., Tempe, AZ (United States); Bertoni, M. [Arizona State Univ., Tempe, AZ (United States)

    2015-04-06

    "Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical band alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface

  19. Assessment of selected metals in the ambient air PM10 in urban sites of Bangkok (Thailand).

    Science.gov (United States)

    Pongpiachan, Siwatt; Iijima, Akihiro

    2016-02-01

    Estimating the atmospheric concentrations of PM10-bounded selected metals in urban air is crucial for evaluating adverse health impacts. In the current study, a combination of measurements and multivariate statistical tools was used to investigate the influence of anthropogenic activities on variations in the contents of 18 metals (i.e., Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Ba, La, Ce and Pb) in ambient air. The concentrations of PM10-bounded metals were measured simultaneously at eight air quality observatory sites during a half-year period at heavily trafficked roads and in urban residential zones in Bangkok, Thailand. Although the daily average concentrations of Al, V, Cr, Mn and Fe were almost equivalent to those of other urban cities around the world, the contents of the majority of the selected metals were much lower than the existing ambient air quality guidelines and standard limit values. The sequence of average values of selected metals followed the order of Al > Fe > Zn > Cu > Pb > Mn > Ba > V > Sb > Ni > As > Cr > Cd > Se > Ce > La > Co > Sc. The probability distribution function (PDF) plots showed sharp symmetrical bell-shaped curves in V and Cr, indicating that crustal emissions are the predominant sources of these two elements in PM10. The comparatively low coefficients of divergence (COD) that were found in the majority of samples highlight that site-specific effects are of minor importance. A principal component analysis (PCA) revealed that 37.74, 13.51 and 11.32 % of the total variances represent crustal emissions, vehicular exhausts and the wear and tear of brakes and tires, respectively.

  20. [The influence of periodontal diseases on the concentration of selected metals in saliva].

    Science.gov (United States)

    Herman, Małgorzata; Golasik, Magdalena; Kurhańska-Flisykowska, Anna; Kulza, Maksymilian; Chesy, Paulina; Wyganowska-Swiatkowska, Marzena; Woźniak, Anna; Seńczuk-Przybyłowksa, Monika; Stopa, Janina; Parczewski, Andrzej; Florek, Ewa; Piekoszewski, Wojciech

    2012-01-01

    Analysis of elements (mainly metals) in biological materials provides a challenge for analytics. It results from complex matrix of this kind of samples and strict requirements for purity at all stages of the analytical process. Over the years many effective methods for determination of metals in body fluids have been developed, which link with searching for the association between elemental composition of human body and various diseases. The aim of the investigation was to study the usefulness of available methodology to determination of selected metals in saliva and blood of patients with periodontitis and healthy controls by two techniques" ICP-MS and ICP-OES. Next statistical analysis of the data statistical was carried out. The influence of periodontal disease upon the concentrations of selected metals (Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Pb and Zn) in saliva was examined, as well the attempt to classify samples of patients with periodontitis and healthy individuals correctly was made. Additionally mutual relations between analytes in examined materials were determined by computing the Pearson's correlation coefficient and principal component analysis (PCA).

  1. Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series

    Science.gov (United States)

    Rodríguez-Albelo, L. Marleny; López-Maya, Elena; Hamad, Said; Ruiz-Salvador, A. Rabdel; Calero, Sofia; Navarro, Jorge A. R.

    2017-02-01

    The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects.

  2. A Potential Waste to be Selected as Media for Metal and Nutrient Removal

    Science.gov (United States)

    Zayadi, N.; Othman, N.; Hamdan, R.

    2016-07-01

    This study describes the potential of application of cassava peel, banana peel, coconut shell, and coconut coir to be selected as metal removal while limestone and steel slag for nutrient removal. The media were characterized by X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscopy-Energy Dispersive X-Ray (FESEM-EDX), and X-Ray Powder Diffraction (XRD). The results of XRF analysis medias show the present of calcium oxide, CaO which confirm the high efficiency in adsorbing metal ions and nutrient which is in agreement with the result of XRD. The characteristics of medias by FTIR analysis also confirmed the involvement of alcohol, carboxylic, alkanes, amines and ethers which play important role to reduce ions while FESEM-EDX indicates the porous structures of study medias. The characterization analysis highlight that cassava peel and steel slag were selected as a potential media in this study.

  3. A microporous metal-organic framework for selective C2H2 and CO2 separation

    Science.gov (United States)

    Lin, Rong-Guang; Lin, Rui-Biao; Chen, Banglin

    2017-08-01

    A quartzlike metal-organic framework with interesting one dimensional channel has been synthesized. It exhibits considerable acetylene and carbon dioxide uptake of 41.5 and 24.6 cm3 g-1, respectively, and relatively high selectivity for separation of C2H2/C2H4, C2H2/CH4, CO2/CH4 and CO2/N2 at ambient condition.

  4. Metal-organic frameworks with high capacity and selectivity for harmful gases

    OpenAIRE

    Britt, David; Tranchemontagne, David; Yaghi, Omar M.

    2008-01-01

    Benchmarks have been established for the performance of six metal-organic frameworks (MOFs) and isoreticular MOFs (IRMOFs, which have the same underlying topology as MOF-5), MOF-5, IRMOF-3, MOF-74, MOF-177, MOF-199, and IRMOF-62, as selective adsorbents for eight harmful gases: sulfur dioxide, ammonia, chlorine, tetrahydrothiophene, benzene, dichloromethane, ethylene oxide, and carbon monoxide. Kinetic breakthrough measurements are used to determine the calculated dynamic adsorption capacity ...

  5. An artificial CO-releasing metalloprotein built by histidine-selective metallation.

    Science.gov (United States)

    Albuquerque, Inês S; Jeremias, Hélia F; Chaves-Ferreira, Miguel; Matak-Vinkovic, Dijana; Boutureira, Omar; Romão, Carlos C; Bernardes, Gonçalo J L

    2015-03-01

    We report the design and synthesis of an aquacarbonyl Ru(II) dication cis-[Ru(CO)2(H2O)4](2+) reagent for histidine (His)-selective metallation of interleukin (IL)-8 at site 33. The artificial, non-toxic interleukin (IL)-8-Ru(II)(CO)2 metalloprotein retained IL-8-dependent neutrophil chemotactic activity and was shown to spontaneously release CO in live cells.

  6. Some properties of copper and selected heavy metal sulfides. A limited literature review

    Energy Technology Data Exchange (ETDEWEB)

    Hermansson, H.P. [Studsvik Material AB, Nykoeping (Sweden)

    1995-06-01

    In the SKB proposal for a Swedish nuclear waste repository, copper canisters are used for encapsulating the spent fuel. The chemical and physical behavior of Copper in the repository environment will therefore be of critical importance for the repository integrity. The present work concerns a literature review of Copper and selected heavy metal sulfides as they are expected to play an important role in the repository environment. The interest is focused on their properties as described by crystal structure, electrical properties, atom mobility, solubility in water, mechanisms of sulfidation and selected thermodynamical data. 56 refs, 14 figs, 5 tabs.

  7. Research of the possibility of using an electrical discharge machining metal powder in selective laser melting

    Science.gov (United States)

    Golubeva, A. A.; Sotov, A. V.; Agapovichev, A. V.; Smelov, V. G.; Dmitriev, V. N.

    2017-02-01

    In this paper the research of a Ni-20Cr-10Fe-3Ti (heat-resistant) alloy metal powder conducted for use in a selective laser melting technology. This metal powder is the slime after electric discharge machining. The technology of cleaning and melting the powder discussed in this article. As a control input of the powder, immediately before 3D printing, dimensional analysis, surface morphology and the internal structure of the powder particles after the treatment were examined using optical and electron microscopes. The powder granules are round, oval, of different diameters with non-metallic inclusions. The internal structure of the particles is solid with no apparent defects. The content of the required diameter of the total volume of test powder granules was 15%. X-ray fluorescence analysis of the powder materials carried out. The possibility of powder melting was investigated in the selective laser melting machine ‘SLM 280HL’. A selection of the melting modes based on the physical properties of the Ni-20Cr-10Fe-3Ti alloy, data obtained from similar studies and a mathematical model of the process. Conclusions on the further investigation of the possibility of using electric discharge machining slime were made.

  8. Functional Mesoporous Metal-Organic Frameworks for the Capture of Heavy Metal Ions and Size-Selective Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Qian-Rong; Yuan, Daqiang; Sculley, Julian; Li, Jian-Rong; Han, Zheng-Bo; Zhou, Hong-Cai

    2010-12-20

    By using Zn₄O(CO₂)₆ as secondary building units (SBUs) and two extended ligands containing amino functional groups, TATAB and BTATB (TATAB = 4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoate and BTATB = 4,4',4''-(benzene-1,3,5-triyltris(azanediyl))tribenzoate), two isostructural mesoporous metal–organic frameworks (MOFs) with cavities up to 2.73 nm, designated as PCN-100 and PCN-101 (PCN represents porous coordination network), have been synthesized. N₂ sorption isotherms of both PCN-100 and -101 showed typical type IV behavior, indicating their mesoporous nature. The TATAB ligand that comprises PCN-100 was employed to capture heavy metal ions (Cd(II) and Hg(II)) by constructing complexes within the pores with a possible coordination mode similar to that found in aminopyridinato complexes. This reveals that mesoporous materials such as PCN-100 can be applied in the elimination of heavy metal ions from waste liquid. In addition, both PCNs-100 and -101 exhibit size-selective catalytic activity toward the Knoevenagel condensation reaction.

  9. Association of soil organic matter with metal phases examined by selective dissolution approach: limitations and advantages

    Science.gov (United States)

    Wagai, R.; Mayer, L. M.

    2014-12-01

    Positive co-variation of organic matter (OM) with iron and aluminum phases has been known for decades in soil and, in case of OM-Fe, in marine sediments. More recent studies point to the metal control on the mean residence time of organic carbon in soils, suggesting that better understanding of the role of these metal phases and the nature of these organo-metal associations would help to improve the models of soil OM dynamics. We developed a selective dissolution approach to assess these associations (Wagai and Mayer, 2007; Wagai et al., 2013). By taking advantage of well-established extraction techniques that were targeted to dissolve specific metal and aluminosilicate phases in soil, we quantified the amounts of OM co-dissolved by the selective dissolution of these inorganic phases. The inherent limitations in this conceptually simple approach include the presence of C-based compounds (often as complexing agent for metal) in the extractants and the lack of selectivity when dissolving specific inorganic phases. The former was resolved by using nitrogen (N), instead of C, as a surrogate for OM because (i) soil N is mostly present as soil OM with relatively narrow C:N ratio, and (ii) the extractants are N free. We were able to partially overcome the lack of selectivity problem by comparing the co-dissolution of OM from a variety of extractants that use reductive, complexation, and acid/alkaline dissolutions. The potential advantages of our approach include the ability (i) to estimate the contribution of specific inorganic phases to OM stabilization, and (ii) to infer the possible modes of the organo-mineral associations that were extracted from field soils (e.g., adsorptive association vs. coprecipitation of organo-metallic complexes). In this presentation, we will further consider the advantages and limitations of this approach (e.g., methodological cautions), present some of the previous and new findings gained from this approach (including its application to

  10. H2 production with low CO selectivity from photocatalytic reforming of glucose on metal/TiO2 catalysts

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    H2 with low CO concentration is produced via photocatalytic reforming of glucose (as a representative of biomass component) on metal/TiO2 catalyst (metals: Pt, Rh, Ru, Ir, Au, Ni, Cu). It is shown that the loaded metals generally enhance the rate of H2 production, while they depress the CO selectivity. Both H2 production and CO selectivity are strongly dependent on the kind of deposited metals on TiO2. For example, Rh/TiO2 catalyst is found to be most active for H2 production while with the most extremely low CO concentration from the photocatalytic reforming of glucose.

  11. Heavy metal distribution in mangrove sediment cores from selected sites along western coast of India

    Directory of Open Access Journals (Sweden)

    P. Vidya

    2016-09-01

    Full Text Available Sediment cores were collected from four different mangrove areas of northern Kerala and southern Karnataka, western coast of India.  The cores were analysed for the concentration of five heavy metals (Pb, Ni, Zn, Cu Fe using Atomic Absorption Spectrometry.  The levels of heavy metals in the present study from all the four sediment cores were in the order Fe > Pb > Zn > Ni > Cu and the mean concentrations of each elements in different cores were comparable.  According to Sediment Quality Guidelines (SQG, the mangrove sediments analysed here were moderately contaminated with Ni and heavily contaminated with Pb.  The increased concentration of Ni and Pb in the sediments might be due to their atmospheric deposition or water discharge from different far away sources since the areas selected for study were not disturbed by direct anthropogenic impacts.  Elevated levels of Fe which is considered to be a common phenomenon in mangrove sediments have also been found in the present study.  Heavy metal levels in sediments showed statistically significant correlations with pH, calcium carbonate and organic matter.  This suggests the influence of physico-chemical parameters on the adsorption, deposition and persistence of heavy metals in mangrove sediments.  The heavy metal concentration and the pollution status of the mangroves of west coast, especially the areas selected in this work are less studied before. Hence the data provide from the present baseline study would be further helpful in remediation and management of mangrove ecosystem. 

  12. Selective oxidation of propane to acrylic acid over mixed metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    Wei Zheng; Zhenxing Yu; Ping Zhang; Yuhang Zhang; Hongying Fu; Xiaoli Zhang; Qiquan Sun; Xinguo Hu

    2008-01-01

    The effects of metal atomic ratio, water content, oxygen content, and calcination temperature on the catalytic perfor-mances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid have been investigated and discussed. Among the catalysts studied, it was found that the MoVTeNbO catalyst calcined at a temperature of 600 ℃ showed the best performance in terms of propane conversion and selectivity for acrylic acid under an atmosphere of nitrogen. An effective MoVTeNbO oxide catalyst for propane selective oxidation to acrylic acid was obtained with a combination of a preferred metal atomic ratio (Mo1 V0.31Te0.23Nb0.12). The optimum reaction condition for the selective oxidation of propane was the molar ratio of C3H81 :O2 : H2O : N1 = 4.4 : 12.8 : 15.3 : 36.9. Under such conditions, the conversion of propane and the maximum yield of acrylic acid reached about 50% and 21%, respectively.

  13. Spatial distribution of selected heavy metals and soil fertility status in south-eastern Serbia

    Science.gov (United States)

    Saljnikov, E.; Mrvic, V.; Cakmak, D.; Nikoloski, M.; Perovic, V.; Kostic, L.; Brebanovic, B.

    2009-04-01

    Environmental pollution by heavy metals is one of the most powerful factors destroying biosphere components that directly affecting agricultural production quality and therefore health of human and animals. Regional soil contamination by heavy metals occurs mainly in industrial areas and in big cities. However, pollutants can be air-and/or water-transferred to big distances and may accumulated far from industrial zone what makes difficult to distinguish original background concentrations of heavy metals in soil. Our study covers south-eastern part of Serbia and is a part of a big project studying soil fertility and heavy metal contamination all around Serbia. Diverse natural characteristics and heterogeneity of soil cover, as well as, human activity greatly influenced soil fertility parameters, while, diverse geological substrate and human activity determined the level of potential geochemical pollution. There are number of industrial factories functioning from the last century on the studied area. Also, close to studied area, there was a mining in the middle of the last century. About 600 soil samples from surface 0-30 cm were investigated for main soil fertility characteristics (pH, humus, available K and P) and concentrations of selected heavy metals (As, Cd, Cr, Ni and Pb). Soils graded as very acidic cover 46% of the area, which are mainly mountains with acidic parent materials. Content of humus in 41% of soil samples were below 3%. The most of the soils (71%) are weakly supplied available phosphorus. While available potassium in more than 70% is presented in the concentrations enough for good soil quality. So, about 75% of studied area is characterized with unfavorable soil fertility properties (extremly low soil pH, very low content of available P, about half of the area maintained low soil humus) that is located under forests, meadows and pastures. Content of heavy metals on studied area in 80% of sampled soils was below maximum allowed concentrations

  14. Selective removals of heavy metals (Pb(2+), Cu(2+), and Cd(2+)) from wastewater by gelation with alginate for effective metal recovery.

    Science.gov (United States)

    Wang, Fei; Lu, Xingwen; Li, Xiao-yan

    2016-05-05

    A novel method that uses the aqueous sodium alginate solution for direct gelation with metal ions is developed for effective removal and recovery of heavy metals from industrial wastewater. The experimental study was conducted on Pb(2+), Cu(2+), and Cd(2+) as the model heavy metals. The results show that gels can be formed rapidly between the metals and alginate in less than 10 min and the gelation rates fit well with the pseudo second-order kinetic model. The optimum dosing ratio of alginate to the metal ions was found to be between 2:1 and 3:1 for removing Pb(2+) and around 4:1 for removing Cu(2+) and Cd(2+) from wastewater, and the metal removal efficiency by gelation increased as the solution pH increased. Alginate exhibited a higher gelation affinity toward Pb(2+) than Cu(2+) and Cd(2+), which allowed a selective removal of Pb(2+) from the wastewater in the presence of Cu(2+) and Cd(2+) ions. Chemical analysis of the gels suggests that the gelation mainly occurred between the metal ions and the -COO(-) and -OH groups on alginate. By simple calcination of the metal-laden gels at 700 °C for 1 h, the heavy metals can be well recovered as valuable resources. The metals obtained after the thermal treatment are in the form of PbO, CuO, and CdO nanopowders with crystal sizes of around 150, 50, and 100 nm, respectively.

  15. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    Science.gov (United States)

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-11-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  16. Heat exchanger selection and design analyses for metal hydride heat pump systems

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Voskuilen, Tyler G.; Waters, Essene L.

    2016-01-01

    This study presents a design analysis for the development of highly efficient heat exchangers within stationary metal hydride heat pumps. The design constraints and selected performance criteria are applied to three representative heat exchangers. The proposed thermal model can be applied to select...... the most efficient heat exchanger design and provides outcomes generally valid in a pre-design stage. Heat transfer effectiveness is the principal performance parameter guiding the selection analysis, the results of which appear to be mildly (up to 13%) affected by the specific Nusselt correlation used....... The thermo-physical properties of the heat transfer medium and geometrical parameters are varied in the sensitivity analysis, suggesting that the length of independent tubes is the physical parameter that influences the performance of the heat exchangers the most. The practical operative regions for each...

  17. Rice straw modified by click reaction for selective extraction of noble metal ions.

    Science.gov (United States)

    Wang, Jingjing; Wei, Jun; Li, Juan

    2015-02-01

    Rice straw was modified by azide-alkyne click reaction in order to realize selective extraction of noble metal ions. The ability of the modified straw to adsorb Pd(2+) and Pt(4+) was assessed using a batch adsorption technique. It was found that the sorption equilibrium could be reached within 1h and the adsorption capacity increased with temperature for both Pd(2+) and Pt(4+). The maximum sorption capacities for Pd(2+) and Pt(4+) were respectively attained in 1.0 and 0.1 mol/L HCl. The modified straw showed excellent selectivity for noble metal ions in comparison to the pristine straw. In addition, the modified straw was examined as a column packing material for extraction of noble metal ions. It was indicated that 1.0 mL/min was the best flow rate for Pd(2+) and Pt(4+). The modified straw could be repeatedly used for 10 times without any significant loss in the initial binding affinity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine.

    Science.gov (United States)

    Xiong, Ying; Adhikari, Chaitanya Raj; Kawakita, Hidetaka; Ohto, Keisuke; Inoue, Katsutoshi; Harada, Hiroyuki

    2009-09-01

    Persimmon waste was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named DMA persimmon waste gel (DMA-PW). It was found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) in hydrochloric acid medium. In contrast, base metals such as Cu(II), Zn(II), Fe(III), and Ni(II) were not practically adsorbed. The formation of ion pairs of the metal chloro complex anions with the protonated adsorption gels was proposed as the main adsorption process. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 5.63 mol/kg dry gel and comparable capacities, i.e., 0.42 and 0.28 mol/kg for Pd(II) and Pt(IV), respectively. According to the kinetic and electrochemical studies, the adsorption rate of Au(III) was greatly enhanced by the chemical modification. Also, its excellent adsorption characteristics for the precious metals were confirmed by adsorption and elution tests using a column packed with the DMA-PW gel.

  19. From ionic-liquid@metal-organic framework composites to heteroatom-decorated large-surface area carbons: superior CO2 and H2 uptake.

    Science.gov (United States)

    Aijaz, Arshad; Akita, Tomoki; Yang, Hui; Xu, Qiang

    2014-06-21

    For the first time, high surface area uniformly nitrogen (N)- and boron-nitrogen (BN)-decorated nanoporous carbons have been successfully fabricated by impregnation of ionic liquids (ILs) within a metal-organic framework (MOF), MIL-100(Al), followed by carbonization, which exhibit remarkable CO2 and H2 adsorption capacities.

  20. Linear and nonlinear surface spectroscopy of supported size selected metal clusters and organic adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Thaemer, Martin Georg

    2012-03-08

    The spectroscopic investigation of supported size selected metal clusters over a wide wavelength range plays an important role for understanding their outstanding catalytic properties. The challenge which must be overcome to perform such measurements is the difficult detection of the weak spectroscopic signals from these samples. As a consequence, highly sensitive spectroscopic methods are applied, such as surface Cavity Ringdown Spectroscopy and surface Second Harmonic Generation Spectroscopy. The spectroscopic apparatus developed is shown to have a sensitivity which is high enough to detect sub-monolayer coverages of adsorbates on surfaces. In the measured spectra of small supported silver clusters of the sizes Ag{sub 4}2, Ag{sub 2}1, Ag{sub 9}, and Ag atoms a stepwise transition from particles with purely metallic character to particles with molecule-like properties can be observed within this size range.

  1. Biphasic catalysis using amphiphilic polyphenols-chelated noble metals as highly active and selective catalysts

    Science.gov (United States)

    Mao, Hui; Yu, Hong; Chen, Jing; Liao, Xuepin

    2013-07-01

    In the field of catalysis, it is highly desired to develop novel catalysts that combine the advantages of both homogeneous and heterogeneous catalysts. Here we disclose that the use of plant pholyphenol as amphiphilic large molecule ligand/stabilizer allows for the preparation of noble metal complex and noble metal nanoparticle catalysts. These catalysts are found to be highly selective and active in aqueous-organic biphasic catalysis of cinnamaldehyde and quinoline, and can be reused at least 3 times without significant loss of activity. Moreover, the catalytic activity and reusability of the catalysts can be rationally controlled by simply adjusting the content of polyphenols in the catalysts. Our strategy may be extended to design a wide range of aqueous-organic biphasic catalysis system.

  2. Origins of the Thick Disk as Traced by the Alpha Elements of Metal-poor Giant Stars Selected from Rave

    NARCIS (Netherlands)

    Ruchti, G. R.; Fulbright, J. P.; Wyse, R. F. G.; Gilmore, G. F.; Bienaymé, O.; Binney, J.; Bland-Hawthorn, J.; Campbell, R.; Freeman, K. C.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Munari, U.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Steinmetz, M.; Watson, F. G.; Williams, M.; Zwitter, T.

    2010-01-01

    Theories of thick-disk formation can be differentiated by measurements of stellar elemental abundances. We have undertaken a study of metal-poor stars selected from the RAVE spectroscopic survey of bright stars to establish whether or not there is a significant population of metal-poor thick-disk st

  3. Effective and selective recovery of gold and palladium ions from metal wastewater using a sulfothermophilic red alga, Galdieria sulphuraria.

    Science.gov (United States)

    Ju, Xiaohui; Igarashi, Kensuke; Miyashita, Shin-Ichi; Mitsuhashi, Hiroaki; Inagaki, Kazumi; Fujii, Shin-Ichiro; Sawada, Hitomi; Kuwabara, Tomohiko; Minoda, Ayumi

    2016-07-01

    The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cells into ammonium solutions containing 0.2M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Metal-organic framework with optimally selective xenon adsorption and separation

    Science.gov (United States)

    Banerjee, Debasis; Simon, Cory M.; Plonka, Anna M.; Motkuri, Radha K.; Liu, Jian; Chen, Xianyin; Smit, Berend; Parise, John B.; Haranczyk, Maciej; Thallapally, Praveen K.

    2016-06-01

    Nuclear energy is among the most viable alternatives to our current fossil fuel-based energy economy. The mass deployment of nuclear energy as a low-emissions source requires the reprocessing of used nuclear fuel to recover fissile materials and mitigate radioactive waste. A major concern with reprocessing used nuclear fuel is the release of volatile radionuclides such as xenon and krypton that evolve into reprocessing facility off-gas in parts per million concentrations. The existing technology to remove these radioactive noble gases is a costly cryogenic distillation; alternatively, porous materials such as metal-organic frameworks have demonstrated the ability to selectively adsorb xenon and krypton at ambient conditions. Here we carry out a high-throughput computational screening of large databases of metal-organic frameworks and identify SBMOF-1 as the most selective for xenon. We affirm this prediction and report that SBMOF-1 exhibits by far the highest reported xenon adsorption capacity and a remarkable Xe/Kr selectivity under conditions pertinent to nuclear fuel reprocessing.

  5. Graphene-Templated Synthesis of Magnetic Metal Organic Framework Nanocomposites for Selective Enrichment of Biomolecules.

    Science.gov (United States)

    Cheng, Gong; Wang, Zhi-Gang; Denagamage, Sachira; Zheng, Si-Yang

    2016-04-27

    Successful control of homogeneous and complete coating of graphene or graphene-based composites with well-defined metal organic framework (MOF) layers is a great challenge. Herein, novel magnetic graphene MOF composites were constructed via a simple strategy for self-assembly of well-distributed, dense, and highly porous MOFs on both sides of graphene nanosheets. Graphene functionalized with magnetic nanoparticles and carboxylic groups on both sides was explored as the backbone and template to direct the controllable self-assembly of MOFs. The prepared composite materials have a relatively high specific surface area (345.4 m(2) g(-1)), and their average pore size is measured to be 3.2 nm. Their relatively high saturation magnetization (23.8 emu g(-1)) indicates their strong magnetism at room temperature. Moreover, the multifunctional composite was demonstrated to be a highly effective affinity material in selective extraction and separation of low-concentration biomolecules from biological samples, in virtue of the size-selection property of the unique porous structure and the excellent affinity of the composite materials. Besides providing a solution for the construction of well-defined functional graphene-based MOFs, this work could also contribute to selective extraction of biomolecules, in virtue of the universal affinity between immobilized metal ions and biomolecules.

  6. Selective Ru ALD as a Catalyst for Sub-Seven-Nanometer Bottom-Up Metal Interconnects.

    Science.gov (United States)

    Zyulkov, Ivan; Krishtab, Mikhail; De Gendt, Stefan; Armini, Silvia

    2017-09-13

    Integrating bottom-up area-selective building-blocks in microelectronics has a disruptive potential because of the unique capability of engineering new structures and architectures. Atomic layer deposition (ALD) is an enabling technology, yet understanding the surfaces and their modification is crucial to leverage area-selective ALD (AS-ALD) in this field. The understanding of general selectivity mechanisms and the compatibility of plasma surface modifications with existing materials and processes, both at research and production scale, will greatly facilitate AS-ALD integration in microelectronics. The use of self-assembled monolayers to inhibit the nucleation and growth of ALD films is still scarcely compatible with nanofabrication because of defectivity and downscaling limitations. Alternatively, in this Research Article, we demonstrate a straightforward H2 plasma surface modification process capable of inhibiting Ru ALD nucleation on an amorphous carbon surface while still allowing instantaneous nucleation and linear growth on Si-containing materials. Furthermore, we demonstrate how AS-ALD enables previously inaccessible routes, such as bottom-up electroless metal deposition in a dual damascene etch-damage free low-k replacement scheme. Specifically, our approach offers a general strategy for scalable ultrafine 3D nanostructures without the burden of subtractive metal patterning and high cost chemical mechanical planarization processes.

  7. Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

    Directory of Open Access Journals (Sweden)

    Zeeshan Nawaz

    2009-12-01

    Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

  8. Superior carrier confinement in InAlN/InGaN/AlGaN double heterostructures grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yi, E-mail: zhaoyi@mail.xidian.edu.cn; Xue, JunShuai; Zhang, JinCheng, E-mail: jchzhang@xidan.edu.cn; Hao, Yue [Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2014-12-01

    InAlN/InGaN/AlGaN double heterostructures were grown and characterized. Temperature-dependent Hall measurements show that the two-dimensional electron gas has a steady density over the entire temperature range tested and a superior transport property compared with the traditional InAlN/GaN single heterostructure at elevated temperatures. The improved performance was attributed to the back barrier, which enhanced the carrier confinement and prevented electrons from spilling into the buffer. In addition, the room-temperature electron mobility of the double heterostructure was 1293 cm{sup 2}/Vs, which is the highest reported for an InGaN-channel heterostructure.

  9. Tris(triazole) tripodal receptors as selective probes for citrate anion recognition and multichannel transition and heavy metal cation sensing.

    Science.gov (United States)

    González, María del Carmen; Otón, Francisco; Espinosa, Arturo; Tárraga, Alberto; Molina, Pedro

    2015-02-01

    The three-armed pyrenyl-triazole receptor 1 behaves as a highly selective fluorescent molecular sensor for citrate anions over similar carboxylates such as malate or tartrate. In addition, this receptor senses Cu(2+) cations through absorption and emission channels even in the presence of Hg(2+) metal cations. The related three-armed ferrocenyl-triazole receptor 2 behaves as a highly selective dual (redox and chromogenic) chemosensor molecule for Pb(2+) metal cations.

  10. Co-selection of antibiotic and heavy metal resistance in freshwater bacteria

    Directory of Open Access Journals (Sweden)

    Andrea Di Cesare

    2016-04-01

    Full Text Available Antibiotic resistant bacteria are found in most environments, especially in highly anthropized waters. A direct correlation between human activities (e.g., pollution and spread and persistence of antibiotic resistant bacteria (ARB and resistance genes (ARGs within the resident bacterial communities appears more and more obvious. Furthermore, the threat posed for human health by the presence of ARB and ARGs in these environments is enhanced by the risk of horizontal gene transfer of resistance genes to human pathogens. Although the knowledge on the spread of antibiotic resistances in waters is increasing, the understanding of the driving factors determining the selection for antibiotic resistance in the environment is still scarce. Antibiotic pollution is generally coupled with contamination by heavy metals (HMs and other chemicals, which can also promote the development of resistance mechanisms, often through co-selecting for multiple resistances. The co-selection of heavy metal resistance genes and ARGs in waters, sediments, and soils, increases the complexity of the ecological role of ARGs, and reduces the effectiveness of control actions. In this mini-review we present the state-of-the-art of the research on antibiotic- and HM-resistance and their connection in the environment, with a focus on HM pollution and aquatic environments. We review the spread and the persistence of HMs and/or ARB, and how it influences their respective gene co-selection. In the last chapter, we propose Lake Orta, a system characterized by an intensive HM pollution followed by a successful restoration of the chemistry of the water column, as a study-site to evaluate the spread and selection of HMs and antibiotic resistances in heavily disturbed environments.

  11. SELECTED PHYSICAL PROPERTIES OF EXTRUDED COMPOSITES TYPE OF POROUS PVC-METAL

    Directory of Open Access Journals (Sweden)

    Aneta Tor-Świątek

    2014-09-01

    Full Text Available The article presents studies of selected physical and mechanical properties of hybrid materials type of polymer-metal. In the frame of this work modification of PVC with the iron and copper powder in amount of 0, 1.5 and 3% and blowing agent in amount of 0, 0.5, 1% was done. Extrudates in a form of pipe were tested to determine density, porosity, maximum tensile stress, stress at break, modulus of elasticity and elongation with break. The samples were also observed in a microscope. The studies have shown significant influence of the added components on the properties tested.

  12. [Synthesis and applications of chiral metal-organic framework in the selective separation of enantiomers].

    Science.gov (United States)

    Qi, Xiaoyue; Li, Xianjiang; Bai, Yu; Liu, Huwei

    2016-01-01

    Chirality is a universal phenomenon in nature. Chiral separation is vitally important in drug development, agricultural chemistry, pharmacology, environmental science, biology and many other fields. Chiral metal-organic frameworks (MOFs) are a new group of porous materials with special topology and designable pore structures, as well as their high specific surface area, porosity, excellent thermal stability, solvent resistance, etc. Thus, chiral MOFs are promising with various applications in the field of analytical chemistry. This review summarizes the synthesis strategies of chiral MOFs and their applications in the selective separation of enantiomers, as well as related mechanism.

  13. Unprecedented selectivity in molecular recognition of carbohydrates by a metal-organic framework.

    Science.gov (United States)

    Yabushita, Mizuho; Li, Peng; Bernales, Varinia; Kobayashi, Hirokazu; Fukuoka, Atsushi; Gagliardi, Laura; Farha, Omar K; Katz, Alexander

    2016-06-04

    Metal-organic framework (MOF) material NU-1000 adsorbs dimers cellobiose and lactose from aqueous solution, in amounts exceeding 1250 mg gNU-1000(-1) while completely excluding the adsorption of the monomer glucose, even in a competitive mode with cellobiose. The MOF also discriminates between dimers consisting of α and β linkages, showing no adsorption of maltose. Electronic structure calculations demonstrate that key to this selective molecular recognition is the number of favorable CH-π interactions made by the sugar with pyrene units of the MOF.

  14. Construction of three lanthanide metal-organic frameworks: Synthesis, structure, magnetic properties and highly selective sensing of metal ions

    Science.gov (United States)

    Zhang, Xiu-Mei; Li, Peng; Gao, Wei; Liu, Feng; Liu, Jie-Ping

    2016-12-01

    Three lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TZI)(H2O)4]·3H2O (Ln=Gd (1) and Tb (2) and Dy (3), H3TZI=5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction reveals that 1-3 are isostructural and display a 1D double chain based on dinuclear motifs with (μ-COO)2 double bridges. Magnetic studies indicate antiferromagnetic interactions in 1, ferromagnetic interactions in 2 and 3. Furthermore, compound 3 displays a slow relaxation behavior. Compound 2 exhibits intense characteristic green emission of Tb(III) ions in the solid state, which can be observed by the naked eye under UV light. Interestingly, 2 can selectively sense Pb2+ and Fe3+ ions through luminescence enhancement and quenching, respectively. The luminescence quenching mechanisms have been investigated in detail. The study on luminescence Ln-MOFs as a probe for sensing Pb2+ and Fe3+ ions is exceedingly rare example.

  15. Ion-selective electrodes with solid contact for heavy metals determination

    Directory of Open Access Journals (Sweden)

    Wardak C.

    2013-04-01

    Full Text Available Potentiometric properties of ion-selective electrodes with solid contact for lead, cadmium and zinc determination were investigated. The ionic liquids (ILs alkyl methyl imidazolium chlorides are used as lipophilic ionic additive to the membrane phase and as transducer media. The basic analytical parameters of the studied electrodes, such as the slope characteristic, the detection limit, response time, lifetime, selectivity coefficients against various inorganic cations as well as the dependence of the electrodes potential on pH were determined. The obtained electrode are characterized by good analytical parameters: theoretical characteristic slope, low detection limit, short response time and very long lifetime. The electrodes was successfully applied to the direct determination of lead, cadmium and zinc ions in waste water samples. The results obtained indicate that the electrodes provide a good alternative for the determination of these heavy metals in real samples.

  16. A microporous Zn(II)-MOF with open metal sites: structure and selective adsorption properties.

    Science.gov (United States)

    Zheng, Xiaofang; Huang, Yumei; Duan, Jingui; Wang, Chenggang; Wen, Lili; Zhao, Jinbo; Li, Dongfeng

    2014-06-14

    A three-dimensional microporous framework, Zn(II)-MOF [Zn(HPyImDC)(DMA)]n (1) (H3PyImDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic, DMA = N,N'-dimethylacetamide), with open metal sites and small-sized pores, exhibits excellent selective capture of CO2 over N2 and CH4 at 273 K, as well as alcohols from water. The excellent CO2 adsorption selectivity of 1 allows its potential use in the capture of CO2 from industrial flue gas or the removal of CO2 from natural gas. More interestingly, compound represents the rare case of porous materials separating propanol isomers, which may be caused by the relative flexibility of the linear n-propanol considering that both n-propanol and i-propanol have similar kinetic diameters.

  17. DFT study on the selective oxidation of vinyl chloride on different metal surfaces

    Institute of Scientific and Technical Information of China (English)

    Ruipeng Ren; Ruixin Xi; Xianyong Pang; Yongkang Lü

    2011-01-01

    Selective epoxidation of vinyl chloride on Ag(111),Pt(111)and Rh(I 11)with pre-adsorbed atomic oxygen has been studied by density functional theory(DFT)calculation with the periodic slab model.The reaction energies and activation energies of the epoxidation reaction are determined.Because of the asymmetry of vinyl chloride,three competitive reaction pathways are investigated.The results indicate that the most possible reaction pathway is pathway Ⅲ.Compared the activation energies of the epoxidation reaction on Ag(111),Pt(111)and Rh(111),it is obvious that the reaction via OMMC(3)on Ag(111)is the most possible process.However,the selectivity to the target product over Ag(111)is the lowest among the three metals.The results also indicate that the formation of chloroacetaldehyde is more favorable than that of chloroepoxide.

  18. Improving the fatigue performance of porous metallic biomaterials produced by Selective Laser Melting.

    Science.gov (United States)

    Van Hooreweder, Brecht; Apers, Yanni; Lietaert, Karel; Kruth, Jean-Pierre

    2017-01-01

    This paper provides new insights into the fatigue properties of porous metallic biomaterials produced by additive manufacturing. Cylindrical porous samples with diamond unit cells were produced from Ti6Al4V powder using Selective Laser Melting (SLM). After measuring all morphological and quasi-static properties, compression-compression fatigue tests were performed to determine fatigue strength and to identify important fatigue influencing factors. In a next step, post-SLM treatments were used to improve the fatigue life of these biomaterials by changing the microstructure and by reducing stress concentrators and surface roughness. In particular, the influence of stress relieving, hot isostatic pressing and chemical etching was studied. Analytical and numerical techniques were developed to calculate the maximum local tensile stress in the struts as function of the strut diameter and load. With this method, the variability in the relative density between all samples was taken into account. The local stress in the struts was then used to quantify the exact influence of the applied post-SLM treatments on the fatigue life. A significant improvement of the fatigue life was achieved. Also, the post-SLM treatments, procedures and calculation methods can be applied to different types of porous metallic structures and hence this paper provides useful tools for improving fatigue performance of metallic biomaterials.

  19. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    Energy Technology Data Exchange (ETDEWEB)

    Cau Dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Lambertin, D.; Lahalle, H.; Antonucci, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Cannes, C.; Delpech, S. [Institut de Physique Nucléaire, CNRS, Univ. Paris-Sud 11, 91406 Orsay Cedex (France)

    2014-10-15

    Highlights: • Binders capable of reducing the pore solution pH compared with Portland cements are reviewed. • The binders are then tested against aluminum corrosion. • Corrosion of aluminum metal is minimal with magnesium phosphate cement. • The H{sub 2} release can be reduced still further by adding LiNO{sub 3} to the mixing solution. • Electrochemical characterizations show that aluminum tends to a passive state. - Abstract: In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  20. Interaction of selected divalent metal ions with human ataxin-3 Q36.

    Science.gov (United States)

    Stawoska, Iwona; Wesełucha-Birczyńska, Aleksandra; Regonesi, Maria Elena; Riva, Matteo; Tortora, Paolo; Stochel, Grazyna

    2009-11-01

    The mode of interaction of ataxin-3 Q36 (AT-3 Q36) with selected endogenous and exogenous metal ions, namely, Zn(2+), Cu(2+), Ni(2+), and Cd(2+), was examined. Metal-ion-induced structural changes of the protein were monitored by fluorescence as well as Fourier transform Raman spectroscopy. We found that the cations tested lead to a decrease in alpha-helical content and a concurrent increase in beta-sheet as well as undefined (beta-turn and random-coil) structures. The most evident effect was observed for copper and nickel cations. After titration with these cations, the AT3 Q36 secondary structure content (27% alpha-helices in the presence of either ion, 31 and 27% beta-sheets for Cu(2+) and Ni(2+), respectively) was similar to that observed for the aggregated form of the protein (27% alpha-helices, 36% beta-sheets). Using the 1-anilinonaphthalene-8-sulfonate hydrophobic fluorescence probe, we showed that the presence of the metal ions tested led to the formation of solvent-exposed hydrophobic patches of AT-3 Q36, and that such an effect decreased with increasing ionic radius.

  1. Efficient selective catalytic reduction of NO by novel carbon-doped metal catalysts made from electroplating sludge.

    Science.gov (United States)

    Zhang, Jia; Zhang, Jingyi; Xu, Yunfeng; Su, Huimin; Li, Xiaoman; Zhou, Ji Zhi; Qian, Guangren; Li, Li; Xu, Zhi Ping

    2014-10-07

    Electroplating sludges, once regarded as industrial wastes, are precious resources of various transition metals. This research has thus investigated the recycling of an electroplating sludge as a novel carbon-doped metal (Fe, Ni, Mg, Cu, and Zn) catalyst, which was different from a traditional carbon-supported metal catalyst, for effective NO selective catalytic reduction (SCR). This catalyst removed >99.7% NO at a temperature as low as 300 °C. It also removed NO steadily (>99%) with a maximum specific accumulative reduced amount (MSARA) of 3.4 mmol/g. Gas species analyses showed that NO removal was accompanied by evolving N2 and CO2. Moreover, in a wide temperature window, the sludge catalyst showed a higher CO2 selectivity (>99%) than an activated carbon-supported metal catalyst. Structure characterizations revealed that carbon-doped metal was transformed to metal oxide in the sludge catalyst after the catalytic test, with most carbon (2.33 wt %) being consumed. These observations suggest that NO removal over the sludge catalyst is a typical SCR where metals/metal oxides act as the catalytic center and carbon as the reducing reagent. Therefore, our report probably provides an opportunity for high value-added utilizations of heavy-metal wastes in mitigating atmospheric pollutions.

  2. One-step surface selective modification of UV-curable hard coatings with photochemical metal organics

    Science.gov (United States)

    Lee, Yoon Kwang; Park, Chang-Sun; Park, Hyung-Ho

    2016-12-01

    An organic-inorganic hybrid bi-layer film with a selective distribution of inorganic components was synthesized from a one-pot process of UV irradiation. A photochemical metal oxide precursor (Sr 2-ethylhexanoate) varying from 0 to 4 wt% was dispersed in UV-curable coating materials. Under UV exposure, the bi-layer started reacting simultaneously but at different rates due to differences in the two UV-condensable components' reactivity. The effects of the dispersed inorganic component on the surface morphology and mechanical properties were investigated by atomic force microscopy and nanoindentation, respectively. The reaction process and rates were studied from linkage change using Fourier transform infrared spectroscopy at various UV exposure times (0-30 min). The elemental distribution and the interface on the coating layer were characterized by X-ray photoelectron spectroscopy from Ar etching, revealing continuous and gradual composition changes in depth. The results showed that a flattened and surface-selectively hardened SrO containing the coating film could be obtained by this simple process. Consequently, a small ratio of photochemical metal oxide reinforced the organic hard coating film's mechanical properties through the formation of an effective SrO top layer.

  3. Selective-area growth and controlled substrate coupling of transition metal dichalcogenides

    Science.gov (United States)

    Bersch, Brian M.; Eichfeld, Sarah M.; Lin, Yu-Chuan; Zhang, Kehao; Bhimanapati, Ganesh R.; Piasecki, Aleksander F.; Labella, Michael, III; Robinson, Joshua A.

    2017-06-01

    Developing a means for true bottom-up, selective-area growth of two-dimensional (2D) materials on device-ready substrates will enable synthesis in regions only where they are needed. Here, we demonstrate seed-free, site-specific nucleation of transition metal dichalcogenides (TMDs) with precise control over lateral growth by utilizing an ultra-thin polymeric surface functionalization capable of precluding nucleation and growth. This polymer functional layer (PFL) is derived from conventional photoresists and lithographic processing, and is compatible with multiple growth techniques, precursors (metal organics, solid-source) and TMDs. Additionally, we demonstrate that the substrate can play a major role in TMD transport properties. With proper TMD/substrate decoupling, top-gated field-effect transistors (FETs) fabricated with selectively-grown monolayer MoS2 channels are competitive with current reported MoS2 FETs. The work presented here demonstrates that substrate surface engineering is key to realizing precisely located and geometrically-defined 2D layers via unseeded chemical vapor deposition techniques.

  4. Major-ion and selected trace-metal chemistry of the Biscayne Aquifer, Southeast Florida

    Science.gov (United States)

    Radell, M.J.; Katz, B.G.

    1991-01-01

    The major-ion and selected trace-metal chemistry of the Biscayne aquifer was characterized as part of the Florida Ground-Water Quality Monitoring Network Program, a multiagency cooperative effort concerned with delineating baseline water quality for major aquifer systems in the State. The Biscayne aquifer is unconfined and serves as the sole source of drinking water for more than 3 million people in southeast Florida. The Biscayne aquifer consists of highly permeable interbedded limestone and sandstone of Pleistocene and Pliocene age underlying most of Dade and Broward Counties and parts of Palm Beach and Monroe Counties. The high permeability is largely caused by extensive carbonate dissolution. Water sampled from 189 wells tapping the Biscayne aquifer was predominantly a calcium bicarbonate type with some mixed types occurring in coastal areas and near major canals. Major - ion is areally uniform throughout the aquifer. According to nonparametric statistical tests of major ions and dissolved solids, the concentrations of calcium, sodium, bicarbonate, and dissolved solids increased significantly with well depth ( 0.05 significance level ), probably a result of less circulation at depth. Potassium and nitrate concentrations decreased significantly with depth. Although the source of recharge to the aquifer varies seasonally, there was no statistical difference in the concentration of major ions in pared water samples from 27 shallow wells collected during wet and dry seasons. Median concentrations for barium, chromium, copper, lead, and manganese were below maximum or secondary maximum contaminant levels set by the US Environmental Protection Agency. The median iron concentration only slightly exceeded the secondary maximum contaminant level. The concentration of barium was significantly related (0.05 significance level) to calcium and bicarbonate concentration. No distinct areal pattern or vertical distribution of the selected trace metals was evident in water from

  5. Microstructured hydroxyl environments and Raman spectroscopy in selected basic transition-metal halides

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Dong; Meng Dong-Dong; Hagihala Masato; Zheng Xu-Guang

    2011-01-01

    Raman vibrational spectra of the selected basic(hydroxyl OH and deuteroxyl OD)transition-metal halides,geometrically frustrated material series α-,β-,γ-Cu2(OH)3Cl,α-Cu2(OH)3Br,β-Ni2(OH)3Cl,β-Co2(OH)3Cl,β-Co2(OH)3Br,γ-Cu2(OD)3Cl,and β-Co2(OD)3Cl are measured at room temperature and analysed to investigate the relationship between the microstructured OH environments and their respective Raman spectra.Among these selected samples,the last two are used to determine the OH stretching vibration region(3600 cm-1-3300 cm-1)and OH bending vibration region(1000 cm-1-600 cm-1)of OH systems in the spectra.Through the comparative analysis of the distances d(metal-O),d(O-halogen),and d(OH),the strong metal-O interaction and trimeric hydrogen bond(C3υ,Cs,or C1 symmetry)are found in every material,but both determine simultaneously an ultimate d(OH),and therefore an OH stretching vibration frequency.According to the approximately linear relationship between the OH stretching vibration frequency and d(OH),some unavailable d(OH)are guessed and some doubtful d(OH)are suggested to be corrected.In addition,it is demonstrated in brief that the OH bending vibration frequency is also of importance to check the more detailed crystal microstructure relating to the OH group.

  6. Lack of dystrophin leads to the selective loss of superior cervical ganglion neurons projecting to muscular targets in genetically dystrophic mdx mice.

    Science.gov (United States)

    De Stefano, M Egle; Leone, Lucia; Lombardi, Loredana; Paggi, Paola

    2005-12-01

    Autonomic imbalance is a pathological aspect of Duchenne muscular dystrophy. Here, we show that the sympathetic superior cervical ganglion (SCG) of mdx mice, which lack dystrophin (Dp427), has 36% fewer neurons than that of wild-type animals. Cell loss occurs around P10 and affects those neurons innervating muscular targets (heart and iris), which, differently from the submandibular gland (non-muscular target), are precociously damaged by the lack of Dp427. In addition, although we reveal altered axonal defasciculation in the submandibular gland and reduced terminal sprouting in all SCG target organs, poor adrenergic innervation is observed only in the heart and iris. These alterations, detected as early as P5, when neuronal loss has not yet occurred, suggest that in mdx mice the absence of Dp427 directly impairs the axonal growth and terminal sprouting of sympathetic neurons. However, when these intrinsic alterations combine with structural and/or functional damages of muscular targets, neuronal death occurs.

  7. Selective enrichment of metal-binding proteins based on magnetic core/shell microspheres functionalized with metal cations.

    Science.gov (United States)

    Fang, Caiyun; Zhang, Lei; Zhang, Xiaoqin; Lu, Haojie

    2015-06-21

    Metal binding proteins play many important roles in a broad range of biological processes. Characterization of metal binding proteins is important for understanding their structure and biological functions, thus leading to a clear understanding of metal associated diseases. The present study is the first to investigate the effectiveness of magnetic microspheres functionalized with metal cations (Ca(2+), Cu(2+), Zn(2+) and Fe(3+)) as the absorbent matrix in IMAC technology to enrich metal containing/binding proteins. The putative metal binding proteins in rat liver were then globally characterized by using this strategy which is very easy to handle and can capture a number of metal binding proteins effectively. In total, 185 putative metal binding proteins were identified from rat liver including some known less abundant and membrane-bound metal binding proteins such as Plcg1, Acsl5, etc. The identified proteins are involved in many important processes including binding, catalytic activity, translation elongation factor activity, electron carrier activity, and so on.

  8. Transition metal (Co, Ni) nanoparticles wrapped with carbon and their superior catalytic activities for the reversible hydrogen storage of magnesium hydride.

    Science.gov (United States)

    Huang, Xu; Xiao, Xuezhang; Zhang, Wei; Fan, Xiulin; Zhang, Liuting; Cheng, Changjun; Li, Shouquan; Ge, Hongwei; Wang, Qidong; Chen, Lixin

    2017-02-01

    Magnesium hydride (MgH2) exhibits long-term stability and has recently been developed as a safe alternative to store hydrogen in the solid state, due to its high capacity of 7.6 wt% H2 and low cost compared to other metal hydrides. However, the high activation energy and poor kinetics of MgH2 lead to inadequate hydrogen storage properties, resulting in low energy efficiency. Nano-catalysis is deemed to be the most effective strategy in improving the kinetics performance of hydrogen storage materials. In this work, robust and efficient architectures of carbon-wrapped transition metal (Co/C, Ni/C) nanoparticles (8-16 nm) were prepared and used as catalysts in the MgH2 system via ball milling to improve its de/rehydrogenation kinetics. Between the two kinds of nano-catalysts, the Ni/C nanoparticles exhibit a better catalytic efficiency. MgH2 doped with 6% Ni/C (MgH2-6%Ni/C) exhibits a peak dehydrogenation temperature of 275.7 °C, which is 142.7, 54.2 and 32.5 °C lower than that of commercial MgH2, milled MgH2 and MgH2 doped with 6% Co/C (MgH2-6%Co/C), respectively. MgH2 doped with 6% Ni/C can release about 6.1 wt% H2 at 250 °C. More importantly, the dehydrogenated MgH2-6%Ni/C is even able to uptake 5.0 wt% H2 at 100 °C within 20 s. Moreover, a cycling test of MgH2 doped with 8% Ni/C demonstrates its excellent hydrogen absorption/desorption stability with respect to both capacity (up to 6.5 wt%) and kinetics (within 8 min at 275 °C for dehydrogenation and within 10 s at 200 °C for rehydrogenation). Mechanistic research reveals that the in situ formed Mg2Ni and Mg2NiH4 nanoparticles can be regarded as advanced catalytically active species in the MgH2-Ni/C system. Meanwhile, the carbon attached around the surface of transition metal nanoparticles can successfully inhibit the aggregation of the catalysts and achieve the steadily, prompting de/rehydrogenation during the subsequent cycling process. The intrinsic catalytic effects and the uniform distributions of Mg2Ni

  9. Genomic selection strategies in dairy cattle breeding programmes: Sexed semen cannot replace multiple ovulation and embryo transfer as superior reproductive technology

    DEFF Research Database (Denmark)

    Pedersen, Louise Dybdahl; Kargo, Morten; Berg, Peer

    2012-01-01

    . However, when all young bull candidates were born following MOET, the results showed that the use of Y-semen in the breeding nucleus tended to decrease the rate of inbreeding as it enabled GS to increase within-family selection. This implies that the benefit from using sexed semen in a modern dairy cattle......The aim of this study was to test whether the use of X-semen in a dairy cattle population using genomic selection (GS) and multiple ovulation and embryo transfer (MOET) increases the selection intensity on cow dams and thereby the genetic gain in the entire population. Also, the dynamics of using...... different types of sexed semen (X, Y or conventional) in the nucleus were investigated. The stochastic simulation study partly supported the hypothesis as the genetic gain in the entire population was elevated when X-semen was used in the production population as GS exploited the higher selection intensity...

  10. Comparison of metals and tetracycline as selective agents for development of tetracycline resistant bacterial communities in agricultural soil

    DEFF Research Database (Denmark)

    Song, Jianxiao; Rensing, Christopher; Holm, Peter Engelund

    2017-01-01

    with unrealistically high levels of tetracycline (up to 100 mg kg(-1)). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant......-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.......Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil...

  11. Relationships between the H and A-O blood types, phosphohexose isomerase and 6-phosphogluconate dehydrogenase red cell enzyme systems and halothane sensitivity, and economic traits in a superior and an inferior selection line of swiss landrace pigs.

    Science.gov (United States)

    Vögeli, P; Stranzinger, G; Schneebeli, H; Hagger, C; Künzi, N; Gerwig, C

    1984-12-01

    Associations between production traits and the genes for halothane sensitivity (HAL), S, A and H blood group systems and phosphohexose isomerase (PHI) and 6-phosphogluconate dehydrogenase (6-PGD) enzyme systems were investigated in two lines of pigs selected for an index. The phenotypic variance-covariance matrix of the index included backfat thickness and daily gain, whereas the genetic variance-covariance matrix included daily gain, feed conversion and percentage of lean meat. The experiment was conducted at the experimental station of the Institute of Animal Production and has been underway since 1973. The same index was applied but in two opposite directions to give a superior and inferior line in relation to the production traits. One hundred twenty-nine animals of the superior line in the seventh generation and 88 animals of the inferior line in the sixth generation were studied. Forty-two percent (54/129) of the animals of the superior line were halothane-positive. No animals in the inferior line were halothane reactors. Of the halothane-positive pigs, 70.4% (38/54) in the superior line had the HaHa and 94.4% (51/54) had the SsSs genotype, whereas only 4% (3/75) of the HaHa and 12% (9/75) of the SsSs pigs were halothane-negative. By practicing selection at the H and S loci, it seems possible to efficiently reduce halothane sensitivity in Swiss Landrace pigs. In pigs of the superior line, there were significant differences in percentage of lean meat, carcass length, pH1 (pH value at 45 min to 1 h postmortem, M. longissimus) and reflectance values among genotypes of the HAL, S and H systems and among some genotypes of the 6-PGD system. Poorest meat quality, highest percentage of lean meat and shortest carcass length were observed in pigs homozygous for the alleles HALn, Ss, Ha, PHIB and 6-PGDA. In the inferior line, these associations were absent. As the HAL locus is associated with the above mentioned production traits, linkage disequilibria may explain the

  12. Superior tree selection of Pinus manssoniana for pulpwood purpose in Guizhou province%贵州省马尾松纸浆材的优树选择研究

    Institute of Scientific and Technical Information of China (English)

    谢维斌; 赵杨; 王琼; 莫周卫; 广春勇

    2012-01-01

    By taking the method of 5 dominant trees comparison, 20 superior trees and 100 dominant trees of Pinus manssoniana were selected from the natural stand in 2 counties of Guizhou province. On the basis of statistical analysis, the selection standard of P. manssoniana plus tree was formulated that the superior tree DBH should be greater than or equal to average DBH's 111 % of the five-dominant-tree, the holocellulose content of the plus tree should be no less than that of five-dominant-tree's mean value, and 1% NaOH extraction content of the superior tree no higher than that of mean value. Crown/height, curvature, cone index, bark index and ormquotient were regarded as the form quality of plus trees, and the comprehensive scoring standard for selection superior trees was established by combing with growth characters and material quality. The selection standard of P. manssoniana plus tree was that the comprehensive scores should be no less than 60 scores. With this standard, the primary selective 20 superior trees were comprehensively evaluated, thus 11 plus trees were finally chosen, the selection rate was 55%, the wood volume of selected plus trees increased by 62% than the control averagely, and wood property was improved. The 11 plus trees can be applied to the construction of the pulpwood orchard of P. manssoniana in Guizhou.%采用5株优势木对比法,在贵州省2个县的马尾松天然林中,共初选出马尾松优树20株,优势木100株.经统计分析,确定贵州省马尾松天然林中的优树初选标准为:优树胸径≥5株优势木平均胸径的111%,综纤维含量不低于优势木均值,1% NaOH抽提物含量不高于均值.以树皮指数、冠高比、结实指数等性状作为优树形质指标,结合生长性状和材性性状,制定了综合评分标准,以综合得分不低于60分为贵州省马尾松纸浆材优树选择标准.对初选的20株优树进行综合评定,从而决选出马尾松优树11株,入选率为55%,入选

  13. Embedding Metal in the Interface of a p-n Heterojunction with a Stack Design for Superior Z-Scheme Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Yin, Wenjie; Bai, Lijie; Zhu, Yuzhen; Zhong, Shuxian; Zhao, Leihong; Li, Zhengquan; Bai, Song

    2016-09-07

    The construction of a p-n heterojunction is an efficient strategy to resolve the limited light absorption and serious charge-carrier recombination in semiconductors and enhance the photocatalytic activity. However, the promotion effect is greatly limited by poor interfacial charge transfer efficiency as well as reduced redox ability of charge carriers. In this work, we demonstrate that the embedding of metal Pd into the interface between n-type C3N4 and p-type Cu2O can further enhance the interfacial charge transfer and increase the redox ability of charge carriers through the design of the C3N4-Pd-Cu2O stack nanostructure. The embedded Pd nanocubes in the stack structure not only trap the charge carriers from the semiconductors in promoting the electron-hole separation but also act as a Z-scheme "bridge" in keeping the strong reduction/oxidation ability of the electrons/holes for surface reactions. Furthermore, Pd nanocubes also increase the bonding strength between the two semiconductors. Enabled by this unique design, the hydrogen evolution achieved is dramatically higher than that of its counterpart C3N4-Cu2O structure without Pd embedding. The apparent quantum efficiency (AQE) is 0.9% at 420 nm for the designed C3N4-Pd-Cu2O. This work highlights the rational interfacial design of heterojunctions for enhanced photocatalytic performance.

  14. Hierarchical hollow Fe2O3@MIL-101(Fe)/C derived from metal-organic frameworks for superior sodium storage

    Science.gov (United States)

    Li, Chengping; Hu, Qian; Li, Yan; Zhou, Hang; Lv, Zhaolin; Yang, Xiangjun; Liu, Lixiang; Guo, Hong

    2016-05-01

    A facile generic template-free strategy is employed to prepare hierarchical hollow hybrid Fe2O3@MIL-101(Fe)/C materials derived from metal-organic frameworks as anode materials for Na-ion batteries. The intrinsic hollow nanostructure can shorten the lengths for both electronic and ionic transport, enlarge the surface areas of electrodes, and improve accommodation of the volume change during Na+ insertion/extraction cycling. Therefore, The stable reversible capacity of Fe2O3@MIL-101(Fe)/C electrode is 710 mAhg‑1, and can be retained at 662 mAhg‑1 after 200 cycles with the retention of 93.2%. Especially, its overall rate performance data confirm again the importance of the hierarchical hollow structures and multi-elements characteristics toward high capacities in both low and high current rates. This general strategy may shed light on a new avenue for fast synthesis of hierarchic hollow functional materials for energy storage, catalyst, sensor and other new applications.

  15. Mechanism study of selective heavy metal ion removal with polypyrrole-functionalized polyacrylonitrile nanofiber mats

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianqiang; Luo, Chao [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Qi, Genggeng [Department of Materials Science and Engineering, Cornell University, Ithaca, NY (United States); Pan, Kai, E-mail: pankai@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Department of Materials Science and Engineering, Cornell University, Ithaca, NY (United States); Cao, Bing, E-mail: bcao@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2014-10-15

    Graphical abstract: - Highlights: • PAN/PPy core/shell nanofiber used for Cr(VI) removal. • Adsorption mechanisms were investigated. • Selective adsorption performances were investigated. - Abstract: Polyacrylonitrile/polypyrrole (PAN/PPy) core/shell nanofiber mat was prepared through electrospinning followed by a simple chemical oxidation method. The polypyrrole-functionalized nanofiber mats showed selective adsorption performance for anions. The interaction between heavy metal anions and polypyrrole (especially the interaction between Cr{sub 2}O{sub 7}{sup 2−} and polypyrrole) during the adsorption process was studied. The results showed that the adsorption process included two steps: one was the anion exchange process between the Cl{sup −} and Cr(VI), and the other was the redox process for the Cr(VI) ions. The adsorption amount was related to the protonation time of the PAN/PPy nanofiber mat and increased as protonation time increased. Meanwhile, the Cr(VI) ions were reduced to Cr(III) through the reaction with amino groups of polypyrrole (from secondary amines to tertiary amines). PAN/PPy nanofiber mat showed high selectivity for Cr(VI), and the adsorption performance was nearly unaffected by other co-existing anions (Cl{sup −}, NO{sub 3}{sup −}, and SO{sub 4}{sup 2−}) except for PO{sub 4}{sup 3−} for the pH change.

  16. Encapsulation of Mono- or Bimetal Nanoparticles Inside Metal-Organic Frameworks via In situ Incorporation of Metal Precursors.

    Science.gov (United States)

    Chen, Liyu; Chen, Xiaodong; Liu, Hongli; Li, Yingwei

    2015-06-10

    A facile, in situ metal precursor incorporation strategy is established for good control over the location and composition of metal nanoparticles within metal-organic frameworks (MOFs). This one-step metal precursor incorporation route is successfully applied to the fabrication of ultrafine Pd, Ni, and PdNi alloys to be selectively encapsulated inside the pores of MOFs, achieving superior catalytic activity and stability in the hydrogenation of nitrobenzene.

  17. Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) for highly selective separations

    Energy Technology Data Exchange (ETDEWEB)

    Yaghi, Omar M

    2012-09-17

    Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) have been investigated for the realization as separation media with high selectivity. These structures are held together with strong bonds, making them architecturally, chemically, and thermally stable. Therefore, employing well designed building units, it is possible to discover promising materials for gas and vapor separation. This grant was focused on the study of MOFs and ZIFs with these specific objectives: (i) to develop a strategy for producing MOFs and ZIFs that combine high surface areas with active sites for their use in gas adsorption and separation of small organic compounds, (ii) to introduce active sites in the framework by a post-synthetic modification and metalation of MOFs and ZIFs, and (iii) to design and synthesize MOFs with extremely high surface areas and large pore volumes to accommodate large amounts of guest molecules. By the systematic study, this effort demonstrated how to introduce active functional groups in the frameworks, and this is also the origin of a new strategy, which is termed isoreticular functionalization and metalation. However, a large pore volume is still a prerequisite feature. One of the solutions to overcome this challenge is an isoreticular expansion of a MOF's structure. With triangular organic linker and square building units, we demonstrated that MOF-399 has a unit cell volume 17 times larger than that of the first reported material isoreticular to it, and it has the highest porosity (94%) and lowest density (0.126 g cm-3) of any MOF reported to date. MOFs are not just low density materials; the guest-free form of MOF-210 demonstrates an ultrahigh porosity, whose BET surface area was estimated to be 6240 m2 g-1 by N2 adsorption measurements.

  18. Spatial Distribution of Selected Heavy Metals in Surface Sediments of the EEZ of the East Coast of Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Hasrizal Shaari

    2015-01-01

    Full Text Available Spatial distribution of selected metals (Al, Fe, Mn, Zn, Cu, and Co in surface sediments in the EEZ of the east coast of Peninsular Malaysia was investigated. The aim of this paper is to determine the distribution pattern and pollution status of heavy metals in tropical shelf sediments since limited information is available. Heavy metal concentrations ranged between 207.58 and 491.33 µg·g−1 for Mn, 36.13 and 125.93 µg·g−1 for Zn, 14.49 and 22.33 µg·g−1 for Cu, 2.00 and 11.12 µg·g−1 for Co, 6.20 and 8.95% for Fe, and 0.94 and 6.62% for Al. The mean concentrations of heavy metals are in decreasing order as follows: Fe > Al > Mn > Zn > Cu > Co. Most metals registered low concentrations at the nearshore areas. Pearson correlation indicates that most of the metals are derived from the miscellaneous sources. Based on the EFs and Igeo, it is implied that the surface sediment trace metal levels in the study area might be enriched by anthropogenic sources. However, the PLI suggests that this area is not contaminated from the measured heavy metals. This work is important to register the current levels of metals so that any change in concentration can be monitored and managed.

  19. Trapping gases in metal-organic frameworks with a selective surface molecular barrier layer

    Science.gov (United States)

    Tan, Kui; Zuluaga, Sebastian; Fuentes, Erika; Mattson, Eric C.; Veyan, Jean-François; Wang, Hao; Li, Jing; Thonhauser, Timo; Chabal, Yves J.

    2016-12-01

    The main challenge for gas storage and separation in nanoporous materials is that many molecules of interest adsorb too weakly to be effectively retained. Instead of synthetically modifying the internal surface structure of the entire bulk--as is typically done to enhance adsorption--here we show that post exposure of a prototypical porous metal-organic framework to ethylenediamine can effectively retain a variety of weakly adsorbing molecules (for example, CO, CO2, SO2, C2H4, NO) inside the materials by forming a monolayer-thick cap at the external surface of microcrystals. Furthermore, this capping mechanism, based on hydrogen bonding as explained by ab initio modelling, opens the door for potential selectivity. For example, water molecules are shown to disrupt the hydrogen-bonded amine network and diffuse through the cap without hindrance and fully displace/release the retained small molecules out of the metal-organic framework at room temperature. These findings may provide alternative strategies for gas storage, delivery and separation.

  20. Distribution of selected carcinogenic hydrocarbon and heavy metals in an oil-polluted agriculture zone.

    Science.gov (United States)

    Nwaichi, E O; Wegwu, M O; Nwosu, U L

    2014-12-01

    Owing to the importance of clean and fertile agricultural soil for the continued existence of man, this study investigated the concentrations of total petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs) and some heavy metals in soils and selected commonly consumed vegetables and tubers from oil-polluted active agricultural farmland in Gokana of Ogoniland, Rivers State, Nigeria. Samples from Umuchichi, Osisioma Local Government Area in Abia State, Nigeria, a non-oil-polluted area constituted the control. In test and control, up to 3,830 ± 19.6 mgkg(-1) dw and 6,950 ± 68.3 mgkg(-1) dw (exceeding DPR set limits) and 11.3 ± 0.04 mgkg(-1) dw and 186 ± 0.02 mgkg(-1) dw for TPH and PAHs, respectively, were recorded in test soil and plant samples, respectively. Among the metals studied (Pb, Cd, Cr, Mn, Fe and Zn), Pb and Cr uptake exceeded WHO set limits for crops in test samples. Combined sources of pollution were evident from our studies. Bitterleaf and Waterleaf could be tried as bioindicators owing to expressed contaminants uptake pattern.

  1. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    Science.gov (United States)

    Cau Dit Coumes, C.; Lambertin, D.; Lahalle, H.; Antonucci, P.; Cannes, C.; Delpech, S.

    2014-10-01

    In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  2. Fe3O4/cyclodextrin polymer nanocomposites for selective heavy metals removal from industrial wastewater.

    Science.gov (United States)

    Badruddoza, Abu Zayed M; Shawon, Zayed Bin Zakir; Tay, Wei Jin Daniel; Hidajat, Kus; Uddin, Mohammad Shahab

    2013-01-02

    In this work, carboxymethyl-β-cyclodextrin (CM-β-CD) polymer modified Fe(3)O(4) nanoparticles (CDpoly-MNPs) was synthesized for selective removal of Pb(2+), Cd(2+), Ni(2+) ions from water. This magnetic adsorbent was characterized by TEM, FTIR, XPS and VSM. The adsorption of all studied metal ions onto CDpoly-MNPs was found to be dependent on pH, ionic strength, and temperature. Batch adsorption equilibrium was reached in 45 min and maximum uptakes for Pb(2+), Cd(2+) and Ni(2+) in non-competitive adsorption mode were 64.5, 27.7 and 13.2 mg g(-1), respectively at 25 °C. Adsorption data were fitted well to Langmuir isotherm and pseudo-second-order models for kinetic study. The polymer grafted on MNPs enhanced the adsorption capacity because of the complexing abilities of the multiple hydroxyl and carboxyl groups in polymer backbone with metal ions. In competitive adsorption experiments, CDpoly-MNPs could preferentially adsorb Pb(2+) ions with an affinity order of Pb(2+)>Cd(2+)>Ni(2+) which can be explained by hard and soft acids and bases (HASB) theory. Furthermore, we explored the recyclability of CDpoly-MNPs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Determination of Trace Metals and Essential Minerals in Selected Fruit Juices in Minna, Nigeria

    Directory of Open Access Journals (Sweden)

    A. I. Ajai

    2014-01-01

    Full Text Available Levels of trace metals and essential minerals in selected fruit juice samples purchased from Minna were determined using atomic absorption spectrophotometer (AAS and Flame photometer. From the obtained result, Cu, Fe, Mn, Na, and Zn were present in all the samples, while Cd, Pb, and Cr were not detectable in all the samples. Concentrations of K range between 1.31 ± 0.10 and 41.20 ± 0.10 mg/100 mL, Na between 15.47 ± 0.15 and 3.50 ± 0.20 mg/100 mL, Mn between Nd and 0.27 ± 0.08 mg/100 mL, Fe between Nd and 0.90 ± 0.05 mg/100 mL, Cu between Nd-0.60 ± 0.00 mg/100 mL, and Zn between Nd-0.09 ± 0.01 mg/100 mL, respectively. The trace metal levels in all the samples were within permissible limit as recommended by WHO for edible foods and drinks and could therefore be taken to compliment the deficiency of these essential minerals from other food sources.

  4. Evaluation of antimicrobial efficacy of nano coated silver-titania metallic plates against selective pathogens

    Directory of Open Access Journals (Sweden)

    Mohamad, S.M.

    2012-01-01

    Full Text Available Aim: Nanotechnology is an increasingly growing field with its current application in Science and Technology for the purpose of manufacture of novel materials at the nanoscale level. Silver-Titania nanoparticles (AgTiO2-NPs have been known to have inhibitory and bactericidal effects.Methodology and Results: In the present study, stable silver-titania nanoparticles coated metallic blocks were prepared for testing their efficacy against selected bacterial pathogens like Escherichia coli and Staphylococcus aureus. In the experimental part, the bacterial pathogens were inoculated on silver-titania nanoparticle coated blocks and the treatment was carried out in „0‟ time and „24‟ h interval and were enumerated.Conclusion, significance and impact of study:The results were compared with the control (uncoated metallic blocks and analyzed by using Japanese Industrial Standard (JIS Z2801:2000 method. From this study, it was concluded that silver-titania nanoparticles has inhibitory effect on bacterial pathogen tested.

  5. Selective synthesis of double helices of carbon nanotube bundles grown on treated metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Sodi, Felipe; Iniguez-Rabago, Agustin; Rosas-Melendez, Samuel; Ballesteros-Villarreal, Monica [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prolongacion Paseo de la Reforma 880, Lomas de Santa Fe (Mexico); Vilatela, Juan J. [IMDEA Materials Institute, E.T.S. de Ingenieros de Caminos, Madrid (Spain); Reyes-Gutierrez, Lucio G.; Jimenez-Rodriguez, Jose A. [Ingenieria Industrial, Grupo JUMEX, Ecatepec de Morelos, Estado de Mexico (Mexico); Palacios, Eduardo [Lab. de Microscopia Electronica de Ultra Alta Resolucion, Instituto Mexicano del Petroleo, San Bartolo Atepehuacan (Mexico); Terrones, Mauricio [Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, PA (United States); Research Center for Exotic Nanocarbons (JST), Shinshu University, Nagano (Japan)

    2012-12-15

    Double-helix microstructures consisting of two parallel strands of hundreds of multi-walled carbon nanotubes (MWCNTs) have been synthesized by chemical vapour deposition of ferrocene/toluene vapours on metal substrates. Growth of coiled carbon nanostructures with site selectivity is achieved by varying the duration of thermochemical pretreatment to deposit a layer of SiO{sub x} on the metallic substrate. Production of multibranched structures of MWCNTs converging in SiO{sub x} microstructure is also reported. In the abstract figure, panel (a) shows a coloured micrograph of a typical double-helix coiled microstructure of MWCNTs grown on SiO{sub x} covered steel substrate. Green and blue show each of the two individual strands of MWCNTs. Panel (b) is an amplification of a SiO{sub x} microparticle (white) on the tip of the double-stranded coil (green and blue). The microparticle guides the collective growth of hundreds of MWCNTs to form the coiled structure. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Facile synthesis of amino-functionalized titanium metal-organic frameworks and their superior visible-light photocatalytic activity for Cr(VI) reduction.

    Science.gov (United States)

    Wang, Hou; Yuan, Xingzhong; Wu, Yan; Zeng, Guangming; Chen, Xiaohong; Leng, Lijian; Wu, Zhibin; Jiang, Longbo; Li, Hui

    2015-04-09

    Porous metal-organic frameworks (MOFs) have been arousing a great interest in exploring the application of MOFs as photocatalyst in environment remediation. In this work, two different MOFs, Ti-benzenedicarboxylate (MIL-125(Ti)) and amino-functionalized Ti-benzenedicarboxylate (NH2-MIL-125(Ti)) were successfully synthesized via a facile solvothermal method. The MIL-125(Ti) and NH2-MIL-125(Ti) were well characterized by XRD, SEM, XPS, N2 adsorption-desorption measurements, thermogravimetric analysis and UV-vis diffuse reflectance spectra (DRS). It is revealed that the NH2-MIL-125(Ti) has well crystalline lattice, large surface area and mesoporous structure, chemical and thermal stability, and enhanced visible-light absorption up to 520 nm, which was associated with the chromophore (amino group) in the organic linker. Compared with MIL-125(Ti), NH2-MIL-125(Ti) exhibited more efficient photocatalytic activity for Cr(VI) reduction from aqueous solution under visible-light irradiation. The addition of hole scavenger, the hole scavenger concentration and the pH value of the reaction solution played important roles in the photo-catalytic reduction of Cr(VI). The presence of Ti(3+)-Ti(4+) intervalence electron transfer was the main reason for photo-excited electrons transportation from titanium-oxo clusters to Cr(VI), facilitating the Cr(VI) reduction under the acid condition. It was demonstrated that amino-functionalized Ti(IV)-based MOFs could be promising visible-light photocatalysts for the treatment of Cr(VI)-contained wastewater.

  7. Selective excitation of plasmons superlocalized at sharp perturbations of metal nanoparticles

    CERN Document Server

    Gorkunov, M V; Podivilov, E V

    2015-01-01

    Sharp metal corners and tips support plasmons localized on the scale of the curvature radius -- superlocalized plasmons. We analyze plasmonic properties of nanoparticles with small and sharp corner- and tip-shaped surface perturbations in terms of hybridization of the superlocalized plasmons, which frequencies are determined by the perturbations shape, and the ordinary plasmons localized on the whole particle. When the frequency of a superlocalized plasmon gets close to that of the ordinary plasmon, their strong hybridization occurs and facilitates excitation of an optical hot-spot near the corresponding perturbation apex. The particle is then employed as a nano-antenna that selectively couples the free-space light to the nanoscale vicinity of the apex providing precise local light enhancement by several orders of magnitude.

  8. Selective organic synthesis through generation and reactivity control of hyper-coordinate metal species.

    Science.gov (United States)

    Hiyama, Tamejiro

    2008-01-01

    This paper is a review of my 40 years of research at Kyoto, Sagamihara, and Yokohama, all based on the generation of hyper-coordinate metal species such as ate complexes and pentacoordinate silicates. The topics are: (i) carbenoid reagents for carbon-carbon bond-forming reactions, (ii) nucleophilic substitution at acetal carbons using aluminate reagents, (iii) preparation of magnesium enolates and its reaction with nitriles, (iv) Cr(II) reagents for reduction of organic halides and highly selective carbon-carbon bond formation, (v) organic synthesis with organosilion reagents/fluoride ions, (vi) cross-coupling reaction of organosilicon compounds, and (vii) silicon-based conjugate addition to alpha,beta-unsaturated carbonyl acceptors.

  9. Experimental Study of the Selective Adsorption of Heavy Metals onto Clay Minerals

    Institute of Scientific and Technical Information of China (English)

    何宏平; 郭九皋; 等

    2000-01-01

    The interaction between minerals and heavy metals has been a hot object of study in environmental science,mineralogy and soil science,Through the selective adsorption experiment of Ca-montomorillonite,illite and kaolinite to Cu2+,Pb2+,Zn2+,Cd2+,and Cr3+ ions at certain conditions,it could be concluded that Cr3+ is most effectively sorbed by all the three minerals.Also,it can be found that Pb2+ shows a strong affinity for illite and kaolinite while cu2+ for montmorillonite .Based on the adsorption experiment at varying pH of solution,it can be found that the amount of heavy etals sorbed by minerals increases with increasing pH of the solution.

  10. Metal- and reagent-free highly selective anodic cross-coupling reaction of phenols.

    Science.gov (United States)

    Elsler, Bernd; Schollmeyer, Dieter; Dyballa, Katrin Marie; Franke, Robert; Waldvogel, Siegfried R

    2014-05-12

    The direct oxidative cross-coupling of phenols is a very challenging transformation, as homo-coupling is usually strongly preferred. Electrochemical methods circumvent the use of oxidizing reagents or metal catalysts and are therefore highly attractive. Employing electrolytes with a high capacity for hydrogen bonding, such as methanol with formic acid or 1,1,1,3,3,3-hexafluoro-2-propanol, a direct electrolysis in an undivided cell provides mixed 2,2'-biphenols with high selectivity. This mild method tolerates a variety of moieties, for example, tert-butyl groups, which are not compatible with other strong electrophilic media but vital for later catalytic applications of the formed products. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Genotype and Phenotypes of an Intestine-Adapted Escherichia coli K-12 Mutant Selected by Animal Passage for Superior Colonization ▿ †

    Science.gov (United States)

    Fabich, Andrew J.; Leatham, Mary P.; Grissom, Joe E.; Wiley, Graham; Lai, Hongshing; Najar, Fares; Roe, Bruce A.; Cohen, Paul S.; Conway, Tyrrell

    2011-01-01

    We previously isolated a spontaneous mutant of Escherichia coli K-12, strain MG1655, following passage through the streptomycin-treated mouse intestine, that has colonization traits superior to the wild-type parent strain (M. P. Leatham et al., Infect. Immun. 73:8039–8049, 2005). This intestine-adapted strain (E. coli MG1655*) grew faster on several different carbon sources than the wild type and was nonmotile due to deletion of the flhD gene. We now report the results of several high-throughput genomic analysis approaches to further characterize E. coli MG1655*. Whole-genome pyrosequencing did not reveal any changes on its genome, aside from the deletion at the flhDC locus, that could explain the colonization advantage of E. coli MG1655*. Microarray analysis revealed modest yet significant induction of catabolic gene systems across the genome in both E. coli MG1655* and an isogenic flhD mutant constructed in the laboratory. Catabolome analysis with Biolog GN2 microplates revealed an enhanced ability of both E. coli MG1655* and the isogenic flhD mutant to oxidize a variety of carbon sources. The results show that intestine-adapted E. coli MG1655* is more fit than the wild type for intestinal colonization, because loss of FlhD results in elevated expression of genes involved in carbon and energy metabolism, resulting in more efficient carbon source utilization and a higher intestinal population. Hence, mutations that enhance metabolic efficiency confer a colonization advantage. PMID:21422176

  12. Selection of Large-Sized Cunninghamia lanceolata Superior Trees and Variation Analysis on the Major Economic Traits%杉木大径材优树选择与主要经济性状变异分析

    Institute of Scientific and Technical Information of China (English)

    郑会全; 梁瑞友; 胡德活; 韦如萍; 王润辉; 晏姝

    2012-01-01

    以胸径为选择指标,对杉木初级种子园23年生子代林大径材优树(胸径≥26 cm)进行选择,共有38个优良单株入选,结果表明:优树胸径现实增益值均超过56%;树高、胸径、单株材积、树皮比率、木材基本密度和木材吸水性等主要经济性状在优树间变异较为广泛,变异系数在10%以上;树高、胸径、单株材积、木材吸水性间呈正相关关系,且达显著或极显著水平,而树皮比率与胸径及单株材积间、木材基本密度与各生长性状及木材吸水性间则为负相关关系,达显著或极显著水平.对大径材优树有效材积(去皮后单株材积)-木材基本密度类型作初步划分发现,共17株优树有效材积值大于优树群体均值,其中优树S14、S18 、S22、S25木材基本密度大于优树群体均值.%Taking DBH as selection index, 38 superior Cunninghamia lanceolata individuals ( DBH ≥ 26cm) were selected from 23yr old progeny plantation inside the primary seed orchard. The realized-gain of DBH of all the superior individuals was all over 56%. Further analysis revealed that the tested economic traits including height, DBH, standing volume, bark ratio ( BR) , wood basic density ( DEN) and wood hygroscopicity ( WH) varied greatly among the superior trees, and the variation coefficient was over 10%. It was also found that the height, DBH, volume, and WH were positively correlated to each other significantly or extremely significantly ( significance <0. 05 or 0. 01) among the superior trees, while there were significant or extremely significant negative correlations between BR and DBH, standing volume, between DEN and WH and each growth index. According to the classification results of the superior trees in VB (volume without bark) and DEN, 17 individuals were identified to have a higher level of VB than that of the mean value of the superior trees population (PM ) , and the DEN value of superior S14 , S18, S22, S25 trees displayed

  13. Highly sensitive and selective detection of mercury (II) based on a zirconium metal-organic framework in aqueous media

    Science.gov (United States)

    Zhang, Xin; Xia, Tifeng; Jiang, Ke; Cui, Yuanjing; Yang, Yu; Qian, Guodong

    2017-09-01

    A novel metal-organic framework (MOF) fluorescent probe UiO-66-PSM is obtained by the copper-catalyzed azide-alkyne click (CuAAC) reaction of UiO-66-N3 with phenylacetylene. The click-generated triazole unit can act as the metal binding site to coordinate with Hg2+, which exhibits the most pronounced fluorescence response (rapid response, excellent selectivity, and high sensitivity) over other metal ions. Moreover, it is capable of detecting Hg2+ in environmental water samples without any structural disintegration of the framework, indicating its high potential in practical applications.

  14. Green methods for preparing highly co2 selective and h2s tolerant metal organic frameworks

    KAUST Repository

    Eddaoudi, Mohamed

    2015-12-23

    A green route for preparing a metal organic framework include mixing metal precursor with a ligand precursor to form a solvent-free mixture; adding droplets of water to the mixture; heating the mixture at a first temperature after adding the water; and isolating the metal organic framework material including the metal and the ligand.

  15. Facile synthesis of amino-functionalized titanium metal-organic frameworks and their superior visible-light photocatalytic activity for Cr(VI) reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hou [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Yuan, Xingzhong, E-mail: yxz@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Wu, Yan [College of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Zeng, Guangming [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Chen, Xiaohong [School of Business, Central South University, Changsha 410083 (China); Leng, Lijian; Wu, Zhibin; Jiang, Longbo [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Li, Hui [Institute of Bio-energy, Hunan Academy of Forestry, Changsha 410004 (China)

    2015-04-09

    Highlights: • NH{sub 2} functionalized MIL-125(Ti) was fabricated by a facile solvothermal method. • The photocatalyst could reduce Cr(VI)–Cr(III) under visible light irradiation. • The Ti{sup 3+}–Ti{sup 4+} intervalence electron transfer is important for Cr(VI) reduction. • Used NH{sub 2}-MIL-125(Ti) can be recycled for the photocatalytic reduction. - Abstract: Porous metal-organic frameworks (MOFs) have been arousing a great interest in exploring the application of MOFs as photocatalyst in environment remediation. In this work, two different MOFs, Ti-benzenedicarboxylate (MIL-125(Ti)) and amino-functionalized Ti-benzenedicarboxylate (NH{sub 2}-MIL-125(Ti)) were successfully synthesized via a facile solvothermal method. The MIL-125(Ti) and NH{sub 2}-MIL-125(Ti) were well characterized by XRD, SEM, XPS, N{sub 2} adsorption–desorption measurements, thermogravimetric analysis and UV–vis diffuse reflectance spectra (DRS). It is revealed that the NH{sub 2}-MIL-125(Ti) has well crystalline lattice, large surface area and mesoporous structure, chemical and thermal stability, and enhanced visible-light absorption up to 520 nm, which was associated with the chromophore (amino group) in the organic linker. Compared with MIL-125(Ti), NH{sub 2}-MIL-125(Ti) exhibited more efficient photocatalytic activity for Cr(VI) reduction from aqueous solution under visible-light irradiation. The addition of hole scavenger, the hole scavenger concentration and the pH value of the reaction solution played important roles in the photo-catalytic reduction of Cr(VI). The presence of Ti{sup 3+}–Ti{sup 4+} intervalence electron transfer was the main reason for photo-excited electrons transportation from titanium-oxo clusters to Cr(VI), facilitating the Cr(VI) reduction under the acid condition. It was demonstrated that amino-functionalized Ti(IV)-based MOFs could be promising visible-light photocatalysts for the treatment of Cr(VI)-contained wastewater.

  16. Anomalous electron transport in metal/carbon multijunction devices by engineering of the carbon thickness and selecting metal layer

    Science.gov (United States)

    Dwivedi, Neeraj; Dhand, Chetna; Rawal, Ishpal; Kumar, Sushil; Malik, Hitendra K.; Lakshminarayanan, Rajamani

    2017-06-01

    A longstanding concern in the research of amorphous carbon films is their poor electrical conductivity at room temperature which constitutes a major barrier for the development of cost effective electronic and optoelectronic devices. Here, we propose metal/carbon hybrid multijunction devices as a promising facile way to overcome room temperature electron transport issues in amorphous carbon films. By the tuning of carbon thickness and swapping metal layers, we observe giant (upto ˜7 orders) reduction of electrical resistance in metal/carbon multijunction devices with respect to monolithic amorphous carbon device. We engineer the maximum current (electrical resistance) from about 10-7 to 10-3 A (˜107 to 103 Ω) in metal (Cu or Ti)/carbon hybrid multijunction devices with a total number of 10 junctions. The introduction of thin metal layers breaks the continuity of relatively higher resistance carbon layer as well as promotes the nanostructuring of carbon. These contribute to low electrical resistance of metal/carbon hybrid multijunction devices, with respect to monolithic carbon device, which is further reduced by decreasing the thickness of carbon layers. We also propose and discuss equivalent circuit model to explain electrical resistance in monolithic carbon and metal/carbon multijunction devices. Cu/carbon multijunction devices display relatively better electrical transport than Ti/carbon devices owing to low affinity of Cu with carbon that restricts carbide formation. We also observe that in metal/carbon multijunction devices, the transport mechanism changes from Poole-Frenkel/Schottky model to the hopping model with a decrease in carbon thickness. Our approach opens a new route to develop carbon-based inexpensive electronic and optoelectronic devices.

  17. Assessing ligand selectivity for uranium over vanadium ions to aid in the discovery of superior adsorbents for extraction of UO2(2+) from seawater.

    Science.gov (United States)

    Ivanov, Alexander S; Bryantsev, Vyacheslav S

    2016-06-28

    Uranium is used as the basic fuel for nuclear power plants, which generate significant amounts of electricity and have life cycle carbon emissions that are as low as renewable energy sources. However, the extraction of this valuable energy commodity from the ground remains controversial, mainly because of environmental and health impacts. Alternatively, seawater offers an enormous uranium resource that may be tapped at minimal environmental cost. Nowadays, amidoxime polymers are the most widely utilized sorbent materials for large-scale extraction of uranium from seawater, but they are not perfectly selective for uranyl, UO2(2+). In particular, the competition between UO2(2+) and VO(2+)/VO2(+) cations poses a significant challenge to the efficient mining of UO2(2+). Thus, screening and rational design of more selective ligands must be accomplished. One of the key components in achieving this goal is the establishment of computational techniques capable of assessing ligand selectivity trends. Here, we report an approach based on quantum chemical calculations that achieves high accuracy in reproducing experimental aqueous stability constants for VO(2+)/VO2(+) complexes with ten different oxygen donor ligands. The predictive power of the developed computational protocol is demonstrated for amidoxime-type ligands, providing greater insights into new design strategies for the development of the next generation of adsorbents with high selectivity toward UO2(2+) over VO(2+)/VO2(+) ions. Importantly, the results of calculations suggest that alkylation of amidoxime moieties present in poly(acrylamidoxime) sorbents can be a potential route to better discrimination between the uranyl and competing vanadium ions in seawater.

  18. Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wen [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Banerjee, Debasis [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Liu, Jian [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Schaef, Herbert T. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Crum, Jarrod V. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Fernandez, Carlos A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Kukkadapu, Ravi K. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nie, Zimin [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nune, Satish K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Motkuri, Radha K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Chapman, Karena W. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Hayes, James C. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Silvers, Kurt L. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Krishna, Rajamani [Van' t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904 1098 XH Amsterdam The Netherlands; McGrail, B. Peter [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Liu, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Thallapally, Praveen K. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-03-08

    Incorporating, a redox active organometallic molIncorporating, a redox active organometallic molecule within a porous matrix is a useful strategy to form redox active composite materials for emerging applications such as energy storage, electro-catalysis and electro-magnetic separation. Herein we report a new class of stable, redox active metal organic composites for oxygen/air separation with exceptional efficiency. In particular, Ferrocene impregnated in a thermally stable hierarchical porous framework showed a saturation uptake capacity of >51 mg/g for oxygen at a very low relative saturation pressure (P/Po) of 0.06. The material shows excellent O2 selectivity from air as evident from experimental and simulated breakthrough experiments. In detail structural analysis using 57Fe-Mössbauer, X-ray photoelectron spectroscopy (XPS) and pair distribution function (PDF) analysis show that of O2 adsorption affinity and selectivity originates by the formation Fe3+-O oxide due to the highly reactive nature of the organometallics imbedded in the porous matrix.

  19. Polyethyleneimine Incorporated Metal-Organic Frameworks Adsorbent for Highly Selective CO2 Capture

    Science.gov (United States)

    Lin, Yichao; Yan, Qiuju; Kong, Chunlong; Chen, Liang

    2013-01-01

    A series of polyethyleneimine (PEI) incorporated MIL-101 adsorbents with different PEI loadings were reported for the first time in the present work. Although the surface area and pore volume of MIL-101 decreased significantly after loading PEI, all the resulting composites exhibited dramatically enhanced CO2 adsorption capacity at low pressures. At 100 wt% PEI loading, the CO2 adsorption capacity at 0.15 bar reached a very competitive value of 4.2 mmol g−1 at 25°C, and 3.4 mmol g−1 at 50°C. More importantly, the resulting adsorbents displayed rapid adsorption kinetics and ultrahigh selectivity for CO2 over N2 in the designed flue gas with 0.15 bar CO2 and 0.75 bar N2. The CO2 over N2 selectivity was up to 770 at 25°C, and 1200 at 50°C. We believe that the PEI based metal-organic frameworks is an attractive adsorbent for CO2 capture. PMID:23681218

  20. 互叶白千层高精油优良单株的选择与等级划分%Selection and grade definition of high-essential-oil superior individuals of Melaleuca altennifolia

    Institute of Scientific and Technical Information of China (English)

    吴丽君; 陈碧华; 翁秋媛; 邱安彬; 李乾振; 吴开金

    2011-01-01

    There were 41 superior individuals selected out primarily through observation by eyes. Based on international criteria of tea-oil, there were 14 superior individuals screened out, with biomass of branches and leaves, content of tea-aee oil, content of terpinen4-ol and 1,8-cineloe as the indexes. By method of polygonal decision, 14 superior individuals were defined into 3 grades, 5 individuals were grade Ⅰ , 3 individuals were grade Ⅱ, 6 individuals were grade Ⅲ. The biomass of branches and leaves of 8 superior individuals were 230.86 - 147.32 g per individual, which were 2.87 - 1.83 times of the average values, eontent of tea-oil reached 1.51% -1.15%, which was 1.70-1.29 times of the average values, and the gain by selection was very significant.%在通过目测初选出的41株优良单株中,以茶树油国际标准(ISO4730-1996)为基准,以枝叶生物量、含油率、4-松油烯醇和1,8-桉叶油素含量为评价指标,运用独立标准选择法,复选出14个高精油优良单株.用多目标决策法将优良单株分为3个等级(1级5株、2级3株、3级6株).8株精选的优良单株,其生物量为230.86-147.32 g ·株-1,为群体平均值的2.87-1.83倍;其含油率达1.51%-1.15%,为群体平均值的1.70-1.29倍,选择增益明显.

  1. Sustainability Study on Heavy Metal Uptake in Neem Biodiesel Using Selective Catalytic Preparation and Hyphenated Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Mirella Elkadi

    2014-04-01

    Full Text Available It is common knowledge that the presence of trace metals in biofuels can be detrimental to the environment and long-term sustainable development. This study provides an insight into selective catalytic preparation of biofuel to compare uptake of trace metals in the biodiesel fraction with preferential base catalysts. The role of specific metal hydroxides in controlling trace metal content in biofuel production is relatively unexplored, and the effect of different homogeneous catalysts (NaOH, KOH on metal retention in biodiesel from commercial neem oil was examined. A detailed study of this nature of catalyst vs. metal uptake is in the interest of sustainable living and could make a significant contribution to biofuels research. Both catalysts displayed variable uptake for certain toxic elements, which was attributed to the behavior of the catalyst in the reaction mixture. A general comparison reflected specific trends in metal retention (ICP-MS with the use of different base catalysts. Challenges encountered by extending the study and using a heterogeneous catalyst (CaO are presented. Our work could play a significant role in influencing catalyzed transesterfication processes to control elemental and toxic metal uptake in biofuels. The impact of our work on sustainable living is presented.

  2. Binding and selectivity of phenazino-18-crown-6-ether with alkali, alkaline earth and toxic metal species: A DFT study

    Science.gov (United States)

    Islam, Nasarul; Chimni, Swapandeep Singh

    2017-02-01

    The interactions of phenazino-crown ether ligands with alkali, alkaline earth and selected toxic species were investigated using density functional theory modelling by employing B3PW91/6-311G ++ (d, p) level of theory. The complex stability was analysed in terms of binding energies, perturbation energies, position of highest molecular orbital and energy gap values. In general, the complexes formed by P18C6-1a ligand with metal cations were found to be more stable than those with P18C6-1b. Among alkali and alkaline earth metals complexes having highest stability was observed for the complex formed by P18C6-1a with Be2+. Computational calculations of P18C6 ligand with toxic metal ions reveals that the P18C6-Cr6+ metal complexes acquire envelop like geometry, leading to higher binding energy values. Comparing the binding energies of neutral and monocations of Ag and Hg, the former had higher value both in neutral as well as monocation state. Thus, the stability of metal complexes is determined not only by the ligand but also by the type of metal ion. In solvent systems the stability constants of metal complexes were found increasing with decreasing permittivity of the solvent. This reflects the inherited polar character of the protic solvents stabilises the cation, resulting in decrease of effective interaction of ligand with the metal ion.

  3. M2(m-dobdc) (M = Mn, Fe, Co, Ni) Metal-Organic Frameworks as Highly-Selective, High-Capacity Adsorbents for Olefin/Paraffin Separations.

    Science.gov (United States)

    Bachman, Jonathan E; Kapelewski, Matthew T; Reed, Douglas A; Gonzalez, Miguel I; Long, Jeffrey R

    2017-10-05

    The metal-organic frameworks M2(m-dobdc) (M = Mn, Fe, Co, Ni; m-dobdc4- = 4,6-dioxido-1,3-benzenedicarboxylate) were evaluated as adsorbents for separating olefins from paraffins. Using single-component and multicomponent equilibrium gas adsorption measurements, we show that the coordinatively-unsaturated M2+ sites in these materials lead to superior performance for the physisorptive separation of ethylene from ethane and propylene from propane relative to any known adsorbent, including para-functionalized structural isomers of the type M2(p-dobdc) (p-dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate). Notably, the M2(m-dobdc) frameworks all exhibit an increased affinity for olefins over paraffins relative to their corresponding structural isomers, with the Fe, Co, and Ni variants showing more than double the selectivity. Among these frameworks, Fe2(m-dobdc) displays the highest ethylene/ethane (> 25) and propylene/propane (> 55) selectivity under relevant conditions, together with olefin capacities exceeding 7 mmol/g. Differential enthalpy calculations in conjunction with structural characterization of ethylene binding in Co2(m-dobdc) and Co2(p-dobdc) via in-situ single-crystal X-ray diffraction reveal that the vast improvement in selectivity arises from enhanced metal-olefin interactions induced by increased charge density at the metal site. Moderate olefin binding enthalpies, below 55 kJ/mol and 70 kJ/mol for ethylene and propylene, respectively, indicate that these adsorbents maintain sufficient reversibility under mild regeneration conditions. Additionally, transient adsorption experiments show fast kinetics, with more than 90% of ethylene adsorption occurring within 30 s after dosing. Breakthrough measurements further indicate that Co2(m-dobdc) can produce high purity olefins without a temperature swing, an important test of process applicability. The excellent olefin/paraffin selectivity, high olefin capacity, rapid adsorption kinetics, and low raw materials

  4. Graphene oxide-rare earth metal-organic framework composites for the selective isolation of hemoglobin.

    Science.gov (United States)

    Liu, Jia-Wei; Zhang, Yue; Chen, Xu-Wei; Wang, Jian-Hua

    2014-07-09

    Graphene oxide-La(BTC)(H2O)6 (H3BTC=1,3,5-benzenetricarboxylic acid) metal organic framework composites (LaMOF-GOn, n = 1-6, corresponding to the percentage of GO at 1, 2, 3, 4, 5, and 10%) are prepared through a simple and large-scale method at room temperature. The obtained composites are characterized by ATR-FTIR spectra, SEM, XRD, TGA, and N2 adsorption-desorption isotherm. The presence of GO significantly changes the morphologies of the composites from spindly rectangular rods to irregular thick blocks and increases their surface area from 14.8 cm(2) g(-1) (LaMOFs) to 26.6 cm(2) g(-1) (LaMOF-GO3), whereas at the same time, the crystalline structure of La(BTC)(H2O)6 is maintained. As a novel solid-phase adsorbent the LaMOF-GO composite exhibits outstanding adsorption properties for proteins. The strong hydrophobic interaction, especially π-π interaction between protein and the composite, is the main driving force for protein adsorption. In particular, highly selective isolation of hemoglobin (Hb) is achieved by using LaMOF-GO3 composite as sorbent in 4 mM B-R buffer containing 0.05 mol L(-1) NaCl at pH 8. The retained Hb could be effectively recovered with a 1 mM B-R buffer at pH 10, giving rise to a recovery of 63%. The practical applicability of the LaMOF-GO3 composite is demonstrated by the selective adsorption of Hb from human whole blood, and SDS-PAGE assays indicate that Hb could be selectively isolated with high purity from biological samples of complex matrixes.

  5. A bio-metal-organic framework for highly selective CO(2) capture: A molecular simulation study.

    Science.gov (United States)

    Chen, Yifei; Jiang, Jianwen

    2010-08-23

    A recently synthesized bio-metal-organic framework (bio-MOF-11) is investigated for CO(2) capture by molecular simulation. The adenine biomolecular linkers in bio-MOF-11 contain Lewis basic amino and pyrimidine groups as the preferential adsorption sites. The simulated and experimental adsorption isotherms of pure CO(2), H(2), and N(2) are in perfect agreement. Bio-MOF-11 exhibits larger adsorption capacities compared to numerous zeolites, activated carbons, and MOFs, which is attributed to the presence of multiple Lewis basic sites and nano-sized channels. The results for the adsorption of CO(2)/H(2) and CO(2)/N(2) mixtures in bio-MOF-11 show that CO(2) is more dominantly adsorbed than H(2) and N(2). With increasing pressure, the selectivity of CO(2)/H(2) initially increases owing to the strong interactions between CO(2) and the framework, and then decreases as a consequence of the entropy effect. However, the selectivity of CO(2)/N(2) monotonically increases with increasing pressure and finally reaches a constant. The selectivities in bio-MOF-11 are higher than in many nanoporous materials. The simulation results also reveal that a small amount of H(2)O has a negligible effect on the separation of CO(2)/H(2) and CO(2)/N(2) mixtures. The simulation study provides quantitative microscopic insight into the adsorption mechanism in bio-MOF-11 and suggests that bio-MOF-11 may be interesting for pre- and post-combustion CO(2) capture.

  6. Fabrication of highly co2 selective metal organic framework membrane using liquid phase epitaxy approach

    KAUST Repository

    Eddaoudi, Mohamed

    2016-01-28

    Embodiments include a method of making a metal organic framework membrane comprising contacting a substrate with a solution including a metal ion and contacting the substrate with a solution including an organic ligand, sufficient to form one or more layers of a metal organic framework on a substrate. Embodiments further include a defect-free metal organic framework membrane comprising MSiF6(pyz)2, wherein M is a metal, wherein the thickness of the membrane is less than 1,000 µm, and wherein the metal organic has a growth orientation along the [110] plane relative to a substrate.

  7. Complete Transmetalation in a Metal-Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media.

    Science.gov (United States)

    Asha, K S; Bhattacharjee, Rameswar; Mandal, Sukhendu

    2016-09-12

    A complete transmetalation has been achieved on a barium metal-organic framework (MOF), leading to the isolation of a new Tb-MOF in a single-crystal (SC) to single-crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core-shell metal exchange through dissociation of metal-ligand bonds. This Tb-MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF.

  8. Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments.

    Science.gov (United States)

    Pattanayak, Deepak K; Fukuda, A; Matsushita, T; Takemoto, M; Fujibayashi, S; Sasaki, K; Nishida, N; Nakamura, T; Kokubo, T

    2011-03-01

    Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and hatching pattern, were investigated using a Ti powder of less than 45 μm particle size. The results show that a fully dense plate thinner than 1.8 mm was obtained when the laser power to scanning speed ratio was greater than 0.5 and the hatch spacing was less than the laser diameter, with a 30 μm thick powder layer. Porous Ti metals with structures analogous to human cancellous bone were fabricated and the compressive strength measured. The compressive strength was in the range 35-120 MPa when the porosity was in the range 75-55%. Porous Ti metals fabricated by SLM were heat-treated at 1300 °C for 1h in an argon gas atmosphere to smooth the surface. Such prepared specimens were subjected to NaOH, HCl, and heat treatment to provide bioactivity. Field emission scanning electron micrographs showed that fine networks of titanium oxide were formed over the whole surface of the porous body. These treated porous bodies formed bone-like apatite on their surfaces in a simulated body fluid within 3 days. In vivo studies showed that new bone penetrated into the pores and directly bonded to the walls within 12 weeks after implantation into the femur of Japanese white rabbits. The percentage bone affinity indices of the chemical- and heat-treated porous bodies were significantly higher than that of untreated implants.

  9. Immobilisation of Cu, Pb and Zn in Scrap Metal Yard Soil Using Selected Waste Materials.

    Science.gov (United States)

    Kamari, A; Putra, W P; Yusoff, S N M; Ishak, C F; Hashim, N; Mohamed, A; Isa, I M; Bakar, S A

    2015-12-01

    Immobilisation of heavy metals in a 30-year old active scrap metal yard soil using three waste materials, namely coconut tree sawdust (CTS), sugarcane bagasse (SB) and eggshell (ES) was investigated. The contaminated soil was amended with amendments at application rates of 0 %, 1 % and 3 % (w/w). The effects of amendments on metal accumulation in water spinach (Ipomoea aquatica) and soil metal bioavailability were studied in a pot experiment. All amendments increased biomass yield and reduced metal accumulation in the plant shoots. The bioconcentration factor and translocation factor values of the metals were in the order of Zn > Cu > Pb. The addition of ES, an alternative source of calcium carbonate (CaCO3), has significantly increased soil pH and resulted in marked reduction in soil metal bioavailability. Therefore, CTS, SB and ES are promising low-cost immobilising agents to restore metal contaminated land.

  10. Review: Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops

    Institute of Scientific and Technical Information of China (English)

    ISLAM Ejaz ul; YANG Xiao-e; HE Zhen-li; MAHMOOD Qaisar

    2007-01-01

    Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants,particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely: inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil (total or bioavailable concentration) that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include: soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary

  11. Flexible metal-organic framework compounds: In situ studies for selective CO{sub 2} capture

    Energy Technology Data Exchange (ETDEWEB)

    Allen, A.J., E-mail: andrew.allen@nist.gov [Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899-8520 (United States); Espinal, L.; Wong-Ng, W. [Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899-8520 (United States); Queen, W.L. [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); The Molecular Foundry, Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA 94720 (United States); Brown, C.M. [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716 (United States); Kline, S.R. [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Kauffman, K.L. [National Energy Technology Laboratory (NETL), US Department of Energy, Pittsburgh, PA 15236 (United States); Culp, J.T. [National Energy Technology Laboratory (NETL), US Department of Energy, Pittsburgh, PA 15236 (United States); URS Corporation, South Park, PA 15219 (United States); Matranga, C. [National Energy Technology Laboratory (NETL), US Department of Energy, Pittsburgh, PA 15236 (United States)

    2015-10-25

    Results are presented that explore the dynamic structural changes occurring in two highly flexible nanocrystalline metal-organic framework (MOF) compounds during the adsorption and desorption of pure gases and binary mixtures. The Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN){sub 4}] and catena-bis(dibenzoylmethanato)-(4,4′-bipyridyl)nickel(II) chosen for this study are 3-D and 1-D porous coordination polymers (PCP) with a similar gate opening pressure response for CO{sub 2} isotherms at 303 K, but with differing degrees of flexibility for structural change to accommodate guest molecules. As such, they serve as a potential model system for evaluating the complex kinetics associated with dynamic structure changes occurring in response to gas adsorption in flexible MOF systems. Insights into the crystallographic changes occurring as the MOF pore structure expands and contracts in response to interactions with CO{sub 2}, N{sub 2}, and CO{sub 2}/N{sub 2} mixtures have been obtained from in situ small-angle neutron scattering and neutron diffraction, combined with ex situ X-ray diffraction structure measurements. The role of structure in carbon capture functionality is discussed with reference to the ongoing characterization challenges and a possible materials-by-design approach. - Graphical abstract: We present in situ small-angle neutron scattering results for two flexible metal-organic frameworks (MOFs). The figure shows that for one (NiBpene, high CO{sub 2} adsorption) the intensity of the Bragg peak for the expandable d-spacing most associated with CO{sub 2} adsorption varies approximately with the isotherm, while for the other (NiDBM-Bpy, high CO{sub 2} selectivity) the d-spacing, itself, varies with the isotherm. The cartoons show the proposed modes of structural change. - Highlights: • Dynamic structures of two flexible MOF CO{sub 2} sorbent compounds are compared in situ. • These porous solid sorbents serve as models for pure & dual gas adsorption. • Different

  12. Do wood mice (Apodemus sylvaticus L.) use food selection as a means to reduce heavy metal intake?

    Energy Technology Data Exchange (ETDEWEB)

    Beernaert, Joke [Evolutionary Biology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)], E-mail: joke.beernaert@ua.ac.be; Scheirs, Jan; Brande, Greet van den; Leirs, Herwig [Evolutionary Biology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Blust, Ronny [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Meulenaer, Bruno de; Camp, John van [Research Group Food Chemistry and Human Nutrition, Department of Food Safety and Food Quality, University of Ghent, Coupure Links 653, B-9000 Gent (Belgium); Verhagen, Ron [Evolutionary Biology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2008-02-15

    Food preference of wood mice from two with heavy metals polluted sites and two unpolluted sites was tested under laboratory and field conditions with two-way choice experiments. In the laboratory, wood mice preferred to eat acorns from unpolluted sites over acorns from polluted sites. Previous experience with polluted food had no influence on food choice. Preference was negatively related to acorn metal content. Furthermore, the nutrient content of the acorn endosperm was consistently lower in polluted sites. We therefore conclude that wood mice used absolute metal concentration in the acorn, nutrient content, or both as a food selection cue. The results of the laboratory experiment could not be confirmed under field conditions. We hypothesized that search time constraints due to the presence of predators, competitors and/or other stress factors in the field have prevented the mice to forage selectively. - Wood mice prefer unpolluted food items over polluted food items in laboratory trials but not in field situations.

  13. Multiple Metal Binding Domains Enhance the Zn(II) Selectivity of the Divalent Metal Ion Transporter AztA

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.; Reyes-Caballero, H.; Li, C.; Scott, R.A.; Giedroc, D.P.

    2009-06-03

    Transition metal-transporting P{sub 1B}-type CPx ATPases play crucial roles in mediating metal homeostasis and resistance in all cells. The degree to which N-terminal metal binding domains (MBDs) confer metal specificity to the transporter is unclear. We show that the two MBDs of the Zn/Cd/Pb effluxing pump Anabaena AztA are functionally nonequivalent, but only with respect to zinc resistance. Inactivation of the a-MBD largely abrogates resistance to high intracellular Zn(II) levels, whereas inactivation of the b-MBD is not as deleterious. In contrast, inactivation of either the a- or b-MBD has little measurable impact on Cd(II) and Pb(II) resistance. The membrane proximal b-MBD binds Zn(II) with a higher affinity than the distal N-terminal a-MBD. Facile Zn(II)-specific intermolecular transfer from the a-MBD to the higher-affinity b-MBD is readily observed by {sup 1}H-{sup 15}N HSQC spectroscopy. Unlike Zn(II), Cd(II) and Pb(II) form saturated 1:1 S{sub 4} or S{sub 3}(O/N) complexes with AztA{sup aHbH}, where a single metal ion bridges the two MBDs. We propose that the tandem MBDs enhance Zn(II)-specific transport, while stabilizing a non-native inter-MBD Cd/Pb cross-linked structure that is a poor substrate and/or regulator for the transporter.

  14. Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction

    DEFF Research Database (Denmark)

    Bagger, Alexander; Ju, Wen; Varela, Ana Sofia

    2017-01-01

    Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting the com...

  15. Synthesis and Selective Coloration of Monoaza Crown Ethers Bearing Picrylamino-type Side Arms for Alkali Metal Salts and Methylamine

    Institute of Scientific and Technical Information of China (English)

    Wei ZENG; Zhi Hua MAO; Mi GONG; Chun Chun ZHANG; Sheng Ying QIN; Jun SU

    2003-01-01

    N-pivot lariat ethers with picrylamino group as a chromophore (1, 2 and 3) have been prepared by reaction of N-(4-aminoaryl)monoaza crown ethers with picryl chrolide, and the selective coloration of 1, 2 and 3 for alkali metal salts and amines has been studied by UV-Vis spectra.

  16. Selective Bifunctional Modification of a Non-catenated Metal-Organic Framework Material via 'Click' Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gadzikwa, Tendai; Farha, Omar K.; Malliakas, Christos D.; Kanatzidis, Mercouri G.; Hupp, Joseph T.; Nguyen, SonBinh T.; NWU

    2009-12-01

    A noncatenated, Zn-based metal-organic framework (MOF) material bearing silyl-protected acetylenes was constructed and postsynthetically modified using 'click' chemistry. Using a solvent-based, selective deprotection strategy, two different organic azides were 'clicked' onto the MOF crystals, resulting in a porous material whose internal and external surfaces are differently functionalized.

  17. Comparison of Metals and Tetracycline as Selective Agents for Development of Tetracycline Resistant Bacterial Communities in Agricultural Soil.

    Science.gov (United States)

    Song, Jianxiao; Rensing, Christopher; Holm, Peter E; Virta, Marko; Brandt, Kristian K

    2017-03-07

    Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [(3)H]leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg(-1)) and Zn (≥264 mg kg(-1)) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg(-1)). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.

  18. Metal concentrations in selected brands of canned fish in Nigeria: estimation of dietary intakes and target hazard quotients.

    Science.gov (United States)

    Iwegbue, Chukwujindu M A

    2015-03-01

    The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, and Zn) were determined in selected brands of canned mackerel, sardine, and tuna in Nigeria with a view to providing information on the dietary intakes of metals and lifelong health hazards associated with the consumption of these products. The concentrations of metals were determined by using atomic absorption spectrometry after acid digestion. The mean concentrations of metals in canned mackerel, sardine, and tuna were found as 0.04-0.58, 0.06-0.44, 0.32-0.83 μg/g for Cd; 0.05-2.82, 0.70-2.98, 0.23-2.56 μg/g for Pb, 1.33-11.33, canned fish were above their permissible limits while other metals occurred at levels below their permissible limits. The estimated daily intakes of metals from consumption of 20.8 g fish per day by a 60 kg body weight adult were below the provisional tolerable daily intakes for Cd, Pb, Ni, Cr, and Cu and recommended daily intakes for Co, Fe, Mn, and Zn. The estimated target hazard quotients of the examined metals were less than 1 in the majority of the samples indicating no long-term health hazard at the present circumstance.

  19. Superior Hiking Trail

    Data.gov (United States)

    Minnesota Department of Natural Resources — Superior Hiking Trail main trail, spurs, and camp spurs for completed trail throughout Cook, Lake, St. Louis and Carlton counties. These data were collected with...

  20. Bathymetry of Lake Superior

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Superior has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more...

  1. Superior Hiking Trail Facilities

    Data.gov (United States)

    Minnesota Department of Natural Resources — Superior Hiking Trail main trail, spurs, and camp spurs for completed trail throughout Cook, Lake, St. Louis and Carlton counties. These data were collected with...

  2. Selective Adsorption of Thiols Using Gold Nanoparticles Supported on Metal Oxides.

    Science.gov (United States)

    Sui, Ruohong; Lesage, Kevin L; Carefoot, Sarah K; Fürstenhaupt, Tobias; Rose, Chelsea J; Marriott, Robert A

    2016-09-13

    Selective capture of thiols from a synthetic hydrogen sulfide containing mixture using supported nanogold materials has been explored for the potential removal of thiols from sour gas production fluids. In this research, TiO2-, Al2O3-, SiO2-, and ZnO-supported gold nanoparticles have been studied for their usage as regeneratable adsorbents to capture CH3SH, C2H5SH, and i-C3H7SH. Au/TiO2 and Au/Al2O3 showed promising properties for removing the thiols efficiently from a gas-phase mixture; however, Au/Al2O3 did catalyze some undesirable side reactions, e.g., carbonyl sulfide formation. It was found that a mild temperature of T = 200 °C was sufficient for regeneration of either Au/TiO2 or Au/Al2O3 adsorbent. The metal oxide mesopores played an important role for accommodating gold particles and chemisorption of the thiols, where smaller pore sizes were found to inhibit the agglomeration/growth of gold particles. The nature of thiol adsorption and the impact of multiple adsorption-desorption cycles on the adsorbents have been studied using electron microscopy, XPS, XRD, GC, and physi/chemiadsorption analyses.

  3. Observation of melting conditions in selective laser melting of metals (SLM)

    Science.gov (United States)

    Thombansen, U.; Abels, Peter

    2016-03-01

    Process observation in 3D printing of metals currently is one of the central challenges. Many companies strive to employ this additive manufacturing process in their production chains in order to gain competitive advantages through added flexibility in product design and embedded features. The new degrees of freedom are accompanied with the challenge to manufacture every detail of the product to the predefined specifications. Products with filigree internal structures for example require a perfect build to deliver the performance that was designed into these structures. Melting conditions determine properties such as grain structure and density of the finished part before it is sent to post processing steps. Monitoring of such melting conditions is still a challenge where the use of photodiodes, pyrometry and camera systems contribute to an overall picture that might identify errors or deviations during the build process. Additional considerations must be made to decide if these sensors are applied coaxially or from a lateral perspective. Furthermore, setting parameters of focal plane array (FPA) sensors are discussed and events that are seen in the machine vision image are compared against the pyrometry data. The resume of the experiments suggests the application of multiple sensors to the selective laser melting process (SLM) as they jointly contribute to an identification of events. These events need to be understood in order to establish cause effect relationships in the future.

  4. Higher-resolution selective metallization on alumina substrate by laser direct writing and electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Ming; Liu, Jianguo, E-mail: liujg@mail.hust.edu.cn; Wang, Suhuan; Ai, Jun; Zeng, Xiaoyan

    2016-03-15

    Graphical abstract: - Highlights: • Mechanisms of laser direct writing and electroless plating were studied. • Active seeds in laser-irradiated zone and laser-affected zone were found to be different. • A special chemical cleaning method with aqua regia was taken. • Higher-resolution copper patterns on alumina ceramic were obtained conveniently. - Abstract: How to fabricate conductive patterns on ceramic boards with higher resolution is a challenge in the past years. The fabrication of copper patterns on alumina substrate by laser direct writing and electroless copper plating is a low cost and high efficiency method. Nevertheless, the lower resolution limits its further industrial applications in many fields. In this report, the mechanisms of laser direct writing and electroless copper plating were studied. The results indicated that as the decomposed products of precursor PdCl{sub 2} have different chemical states respectively in laser-irradiated zone (LIZ) and laser-affected zone (LAZ). This phenomenon was utilized and a special chemical cleaning method with aqua regia solution was taken to selectively remove the metallic Pd in LAZ, while kept the PdO in LIZ as the only active seeds. As a result, the resolution of subsequent copper patterns was improved significantly. This technique has a great significance to develop the microelectronics devices.

  5. Historical trends in U.S. mineral statistics for selected non-ferrous metals

    Science.gov (United States)

    Piper, David Z.; Nokleberg, Warren J.

    2002-01-01

    Production figures for selected nonferrous metals-aluminum (including bauxite and alumina), copper, lead, tin, titanium, and zinc-by the United States, as well as other statistics for these commodities, show strong volatility during 20th century. Major shifts were driven by the Great Depression and the two World Wars, but other major temporal changes are also noted that are not directly related to such global crises. For example, the price of tin exhibited a strong maximum in the 1980's, which is unrelated to world production, but rather to failed efforts of the International Tin Council to control price. In the case of copper, U.S. exports have varied throughout the second half of the century, by more than a factor of 5. Such volatility might be explained in part by global economic conditions, at least throughout recent decades. Supporting the interpretation of the importance of foreign pressure on the domestic commodities market is a close correlation between domestic consumption of antimony and its elevated price in the mid 1980's,possibly pushed up mostly by the world dominance in production of this commodity by China. However, only very superficial explanations can be advanced for such relations before we have examined, in concert, information for a much larger suite of commodities.

  6. Graphene oxide/metal nanocrystal multilaminates as the atomic limit for safe and selective hydrogen storage.

    Science.gov (United States)

    Cho, Eun Seon; Ruminski, Anne M; Aloni, Shaul; Liu, Yi-Sheng; Guo, Jinghua; Urban, Jeffrey J

    2016-02-23

    Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage (6.5 wt% and 0.105 kg H2 per litre in the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. These multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.

  7. Design of heterogeneous photocatalysts based on metal oxides to control the selectivity of chemical reactions.

    Science.gov (United States)

    Maldotti, Andrea; Molinari, Alessandra

    2011-01-01

    Photocatalysis is particularly relevant in order to realize chemical transformations of interest in synthesis and, at the same time, to move towards a "sustainable chemistry" with a minimal environmental impact. Heterogeneous systems with well-defined textural characteristics represent a suitable means to tailor the selectivity of photocatalytic processes. Here, we summarize and classify the significant features of photocatalysts consisting of photoactive metal oxides dispersed on high-surface-area solid supports, or constrained inside their porous network. These systems are based on the use of titanium dioxide, highly dispersed oxides of titanium, chromium, vanadium, and polyoxotungstates. They share similar primary photoprocesses: light absorption induces a charge separation process with formation of positive holes able to oxidize organic substrates. A great number of the papers discussed here concern oxidation reactions carried out in the presence of O₂ for inducing partial oxidation of alcohols and monooxygenation of hydrocarbons. We also devote some attention to photocatalysis in the absence of O₂. In these conditions, the photogenerated charge separation offers the possibility to induce the formation of C-C and C-N bonds. We emphasize that the optimal tailoring of photoactive materials for synthetic purposes can be achieved by combining recent advances in the preparation of nanostructured materials with mechanistic knowledge derived from surface science and molecular level investigations.

  8. Selective Surface Charge Sign Reversal on Metallic Carbon Nanotubes for Facile Ultrahigh Purity Nanotube Sorting.

    Science.gov (United States)

    Wang, Jing; Nguyen, Tuan Dat; Cao, Qing; Wang, Yilei; Tan, Marcus Y C; Chan-Park, Mary B

    2016-03-22

    Semiconducting (semi-) single-walled carbon nanotubes (SWNTs) must be purified of their metallic (met-) counterparts for most applications including nanoelectronics, solar cells, chemical sensors, and artificial skins. Previous bulk sorting techniques are based on subtle contrasts between properties of different nanotube/dispersing agent complexes. We report here a method which directly exploits the nanotube band structure differences. For the heterogeneous redox reaction of SWNTs with oxygen/water couple, the aqueous pH can be tuned so that the redox kinetics is determined by the availability of nanotube electrons only at/near the Fermi level, as predicted quantitatively by the Marcus-Gerischer (MG) theory. Consequently, met-SWNTs oxidize much faster than semi-SWNTs and only met-SWNTs selectively reverse the sign of their measured surface zeta potential from negative to positive at the optimized acidic pH when suspended with nonionic surfactants. By passing the redox-reacted nanotubes through anionic hydrogel beads, we isolate semi-SWNTs to record high electrically verified purity above 99.94% ± 0.04%. This facile charge sign reversal (CSR)-based sorting technique is robust and can sort SWNTs with a broad diameter range.

  9. Graphene oxide/metal nanocrystal multilaminates as the atomic limit for safe and selective hydrogen storage

    Science.gov (United States)

    Cho, Eun Seon; Ruminski, Anne M.; Aloni, Shaul; Liu, Yi-Sheng; Guo, Jinghua; Urban, Jeffrey J.

    2016-02-01

    Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage (6.5 wt% and 0.105 kg H2 per litre in the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. These multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.

  10. Selective Separation of Similar Metals in Chloride Solution by Sulfide Precipitation Under Controlled Potential

    Science.gov (United States)

    Liu, Weifeng; Sun, Baiqi; Zhang, Duchao; Chen, Lin; Yang, Tianzu

    2017-08-01

    A new process of sulfide precipitation under controlled potential was proposed to separate selectively similar metals in a Bis(2-ethylhexyl) phosphoric acid (P204) stripping solution of the Co extraction system. Theoretical calculations revealed that Cu2+, Co2+, Zn2+, and Mn2+ could be separated by fractional precipitation with sulfide by controlling the solution potential and pH value simultaneously. The results demonstrated a Cu precipitation ratio reaching 99.9% during sulfide precipitation of Cu at the potential of 330 mV; the Cu/Co mass ratio in the Cu precipitate was 224. The Co precipitation ratio in the xanthate precipitation of Co, at a potential of 170 mV, was 99.9%, and the Co/Zn mass ratio in the Co precipitate was 28.0. The Zn precipitation ratio reached 99.9% for sulfide precipitation of Zn at the potential of 30 mV, and the Zn/Mn mass ratio in the Zn precipitate was 1.41. The Mn precipitation ratio reached 99.9% after neutralization.

  11. Selective extraction of heavy metals from two real calcium-rich contaminated soils by a modified NTA.

    Science.gov (United States)

    Picard, François; Chaouki, Jamal

    2016-11-15

    The objective of this work is to evaluate the selectivity and solubility of a buffer chelant. The buffer chelant is ethylenediamine-nitrilotriacetic acid (NTA·3EDA) and its performance is compared to NTA. All experiments were conducted on batches of 25g of soil in an autoclave at 25°C or 75°C with a constant L:S ratio of 2. The experiments were conducted under a CO2 overhead to lower the reaction pH. The buffer chelant allows a 5-fold selectivity increase for heavy metals while increasing or maintaining the same molar extraction yield compared to NTA. These selectivity and extraction results stand out from those obtained with other neutralized NTA. NTA, EDA and the acid gas CO2 are the three necessary ligands in the NTA·3EDA extraction mechanism. A reaction temperature setpoint increase causes a higher Fe dissolution. However, this does not lower the NTA and NTA·3EDA selectivity for heavy metals. Thus, Fe is a non-interfering cation in the NTA and NTA·3EDA extraction mechanisms. This non-interference is less apparent in the NTA extraction mechanism. The present work intends to share another perspective on the design of more selective and soluble chelants for heavy metal extraction.

  12. FMOS near-IR spectroscopy of Herschel selected galaxies: star formation rates, metallicity and dust attenuation at z~1

    CERN Document Server

    Roseboom, I G; Sumiyoshi, M; Wang, L; Dalton, G; Akiyama, M; Bock, J; Bonfield, D; Buat, V; Casey, C; Chapin, E; Clements, D L; Conley, A; Curtis-Lake, E; Cooray, A; Dunlop, J S; Farrah, D; Ham, S J; Ibar, E; Iwamuro, F; Kimura, M; Lewis, I; Macaulay, E; Magdis, G; Maihara, T; Marsden, G; Mauch, T; Moritani, Y; Ohta, K; Oliver, S J; Page, M J; Schulz, B; Scott, Douglas; Symeonidis, M; Takato, N; Tamura, N; Totani, T; Yabe, K; Zemcov, M

    2012-01-01

    We investigate the properties (e.g. star formation rate, dust attentuation, stellar mass and metallicity) of a sample of infrared luminous galaxies at z \\sim 1 via near-IR spectroscopy with Subaru-FMOS. Our sample consists of Herschel SPIRE and Spitzer MIPS selected sources in the COSMOS field with photometric redshifts in the range 0.7 = 0.51\\pm0.27 for = 10^12 Lsol sources at = 1.36. By comparing star formation rates estimated from the IR and from the dust uncorrected H{\\alpha} line we find a strong relationship between dust attenuation and star formation rate. This relation is broadly consistent with that previously seen in star-forming galaxies at z ~ 0.1. Finally, we investigate the metallicity via the N2 ratio, finding that z ~ 1 IR-selected sources are indistinguishable from the local mass-metallicity relation. We also find a strong correlation between dust attentuation and metallicity, with the most metal-rich IR-sources experiencing the largest levels of dust attenuation.

  13. Overexpression of the multidrug resistance-associated protein (MRP1) in human heavy metal-selected tumor cells.

    Science.gov (United States)

    Vernhet, L; Courtois, A; Allain, N; Payen, L; Anger, J P; Guillouzo, A; Fardel, O

    1999-01-29

    Cellular and molecular mechanisms involved in the resistance to cytotoxic heavy metals remain largely to be characterized in mammalian cells. To this end, we have analyzed a metal-resistant variant of the human lung cancer GLC4 cell line that we have selected by a step-wise procedure in potassium antimony tartrate. Antimony-selected cells, termed GLC4/Sb30 cells, poorly accumulated antimony through an enhanced cellular efflux of metal, thus suggesting up-regulation of a membrane export system in these cells. Indeed, GLC4/Sb30 cells were found to display a functional overexpression of the multidrug resistance-associated protein MRP1, a drug export pump, as demonstrated by Western blotting, reverse transcriptase-polymerase chain reaction and calcein accumulation assays. Moreover, MK571, a potent inhibitor of MRP1 activity, was found to markedly down-modulate resistance of GLC4/Sb30 cells to antimony and to decrease cellular export of the metal. Taken together, our data support the conclusion that overexpression of functional MRP1 likely represents one major mechanism by which human cells can escape the cytotoxic effects of heavy metals.

  14. Heterogeneous behavior of metalloproteins toward metal ion binding and selectivity: insights from molecular dynamics studies.

    Science.gov (United States)

    Gogoi, Prerana; Chandravanshi, Monika; Mandal, Suraj Kumar; Srivastava, Ambuj; Kanaujia, Shankar Prasad

    2016-07-01

    About one-third of the existing proteins require metal ions as cofactors for their catalytic activities and structural complexities. While many of them bind only to a specific metal, others bind to multiple (different) metal ions. However, the exact mechanism of their metal preference has not been deduced to clarity. In this study, we used molecular dynamics (MD) simulations to investigate whether a cognate metal (bound to the structure) can be replaced with other similar metal ions. We have chosen seven different proteins (phospholipase A2, sucrose phosphatase, pyrazinamidase, cysteine dioxygenase (CDO), plastocyanin, monoclonal anti-CD4 antibody Q425, and synaptotagmin 1 C2B domain) bound to seven different divalent metal ions (Ca(2+), Mg(2+), Zn(2+), Fe(2+), Cu(2+), Ba(2+), and Sr(2+), respectively). In total, 49 MD simulations each of 50 ns were performed and each trajectory was analyzed independently. Results demonstrate that in some cases, cognate metal ions can be exchanged with similar metal ions. On the contrary, some proteins show binding affinity specifically to their cognate metal ions. Surprisingly, two proteins CDO and plastocyanin which are known to bind Fe(2+) and Cu(2+), respectively, do not exhibit binding affinity to any metal ion. Furthermore, the study reveals that in some cases, the active site topology remains rigid even without cognate metals, whereas, some require them for their active site stability. Thus, it will be interesting to experimentally verify the accuracy of these observations obtained computationally. Moreover, the study can help in designing novel active sites for proteins to sequester metal ions particularly of toxic nature.

  15. New metal-organic frameworks with large cavities: selective sorption and desorption of solvent molecules.

    Science.gov (United States)

    Wang, Yan; Huang, Yong-Qing; Liu, Guang-Xiang; Okamura, Taka-aki; Doi, Mototsugu; Sheng, Yue-Wei; Sun, Wei-Yin; Ueyama, Norikazu

    2007-01-01

    Five novel transition metal complexes [Cd(II) (3)(tpba-2)(2)(SCN)(6)].6 THF.3 H(2)O (1), [Cu(II) (3)(tpba-2)(2)(SCN)(6)].6 THF.3 H(2)O (2), [Ni(II) (3)(tpba-2)(2)(SCN)(6)].6 THF.3 H(2)O (3), [Cd(II) (2)(tpba-2)(SCN)(3)]ClO(4) (4), [Cu(I) (3)(SCN)(6)(H(3)tpba-2)] (5) [TPBA-2 = N',N'',N'''-tris(pyrid-2-ylmethyl)-1,3,5-benzenetricarboxamide, THF=tetrahydrofuran] were obtained by reactions of the corresponding transition metal salts with TPBA-2 ligand in the presence of NH(4)SCN using layering or solvothermal method, respectively. The results of X-ray crystallographic analysis showed that complexes 1, 2 and 3 are isostructural and have the same 2D honeycomb network structure with Kagomé lattice, in which all the M(II) (M = Cd, Cu, Ni) atoms are six-coordinated, and the TPBA-2 ligands adopt cis,cis,cis conformation while the thiocyanate anions act as terminal ligands. Capsule-like motifs are found in 1, 2 and 3, in which six THF molecules are hosted, and the results of XPRD and solid-state (13)C NMR spectral measurements showed that the compound 1 can selectively desorb and adsorb THF molecules occurring along with the re-establishment of its crystallinity. In contrast to 1, 2 and 3, complex 4 has different 2D network structure, resulting from TPBA-2 ligands with cis,trans,trans conformation, thiocyanate anions serving as end-to-end bridging ligands, and the incomplete replacement of perchlorate anions, which further link the 2D layers into 3D framework by the hydrogen bonds. In complex 5, the Cu(II) atoms are reduced to Cu(I) during the process of solvothermal reaction, and the Cu(I) atoms are connected by thiocyanate anions to form a 3D porous framework, in which the protonated TPBA-2 ligands are hosted in the cavities as templates.

  16. Elucidation of Mechanisms and Selectivities of Metal-Catalyzed Reactions using Quantum Chemical Methodology.

    Science.gov (United States)

    Santoro, Stefano; Kalek, Marcin; Huang, Genping; Himo, Fahmi

    2016-05-17

    Quantum chemical techniques today are indispensable for the detailed mechanistic understanding of catalytic reactions. The development of modern density functional theory approaches combined with the enormous growth in computer power have made it possible to treat quite large systems at a reasonable level of accuracy. Accordingly, quantum chemistry has been applied extensively to a wide variety of catalytic systems. A huge number of problems have been solved successfully, and vast amounts of chemical insights have been gained. In this Account, we summarize some of our recent work in this field. A number of examples concerned with transition metal-catalyzed reactions are selected, with emphasis on reactions with various kinds of selectivities. The discussed cases are (1) copper-catalyzed C-H bond amidation of indoles, (2) iridium-catalyzed C(sp(3))-H borylation of chlorosilanes, (3) vanadium-catalyzed Meyer-Schuster rearrangement and its combination with aldol- and Mannich-type additions, (4) palladium-catalyzed propargylic substitution with phosphorus nucleophiles, (5) rhodium-catalyzed 1:2 coupling of aldehydes and allenes, and finally (6) copper-catalyzed coupling of nitrones and alkynes to produce β-lactams (Kinugasa reaction). First, the methodology adopted in these studies is presented briefly. The electronic structure method in the great majority of these kinds of mechanistic investigations has for the last two decades been based on density functional theory. In the cases discussed here, mainly the B3LYP functional has been employed in conjunction with Grimme's empirical dispersion correction, which has been shown to improve the calculated energies significantly. The effect of the surrounding solvent is described by implicit solvation techniques, and the thermochemical corrections are included using the rigid-rotor harmonic oscillator approximation. The reviewed examples are chosen to illustrate the usefulness and versatility of the adopted methodology in

  17. An examination of the association of selected toxic metals with total and central obesity indices: NHANES 99-02.

    Science.gov (United States)

    Padilla, Miguel A; Elobeid, Mai; Ruden, Douglas M; Allison, David B

    2010-09-01

    It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten). Some of the associations were significant direct relationships (barium and thallium), and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead). Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings.

  18. An Estimate of the Age Distribution of Terrestrial Planets in the Universe Quantifying Metallicity as a Selection Effect

    CERN Document Server

    Lineweaver, C H

    2000-01-01

    Planets like the Earth cannot form unless elements heavier than helium are available. These heavy elements, or `metals', were not produced in the big bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that the presence of giant extrasolar planets at small distances from their host stars, is strongly correlated with high metallicity of the host stars. The presence of these close-orbiting giants is incompatible with the existence of earth-like planets. Thus, there may be a Goldilocks selection effect: with too little metallicity, earths are unable to form for lack of material, with too much metallicity giant planets destroy earths. Here I quantify these effects and obtain the probability, as a function of metallicity, for a stellar system to harbour an earth-like planet. I combine this probability with current estimates of the star formation rate and of the gradual build up of metals in the Universe to obtain an estimate...

  19. Selective electrodesorption based atomic layer deposition (SEBALD): a novel electrochemical route to deposit metal clusters on Ag(111).

    Science.gov (United States)

    Innocenti, M; Bellandi, S; Lastraioli, E; Loglio, F; Foresti, M L

    2011-09-20

    The possibility of synergic effects of some metals on the catalytic activity of silver led us to study the way to perform controlled deposition on silver. In fact, many metals of technological interest such as Co, Ni, and Fe cannot be deposited at underpotential on silver, and any attempt to control the deposition at overpotential, even at potentials slightly negative of the Nernst value, did not allow an effective control. However, due to the favorable energy gain involved in the formation of the corresponding sulfides, these metals can be deposited at underpotential on sulfur covered silver. The deposition is surface limited and the successive electrodesorption of sulfur leaves confined clusters of metals. The method can also be used to obtain metal clusters of different size. In fact, the alternate underpotential deposition of elements that form a compound is the basis of the electrochemical atomic layer epitaxy (ECALE), and the reiteration of the basic cycle allows us to obtain sulfide deposits whose thickness increases with the number of cycles. Therefore, the successive selective desorption of sulfur leaves increasing amounts of metals.

  20. An Examination of the Association of Selected Toxic Metals with Total and Central Obesity Indices: NHANES 99-02

    Directory of Open Access Journals (Sweden)

    Douglas M. Ruden

    2010-08-01

    Full Text Available It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten. Some of the associations were significant direct relationships (barium and thallium, and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead. Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings.

  1. Do wood mice (Apodemus sylvaticus L.) use food selection as a means to reduce heavy metal intake?

    DEFF Research Database (Denmark)

    Beernaert, Joke; Scheirs, Jan; Brande, Greet Van Den

    2008-01-01

    experience with polluted food had no influence on food choice. Preference was negatively related to acorn metal content. Furthermore, the nutrient content of the acorn endosperm was consistently lower in polluted sites. We therefore conclude that wood mice used absolute metal concentration in the acorn......, nutrient content, or both as a food selection cue. The results of the laboratory experiment could not be confirmed under field conditions. We hypothesized that search time constraints due to the presence of predators, competitors and/or other stress factors in the field have prevented the mice to forage...

  2. Determination of heavy metals in dust from selected nursery and kindergarten classrooms within the Kumasi metropolis of Ghana

    OpenAIRE

    Marian Asantewah Nkansah; Joseph Richmond Fianko; Stephen Mensah; Michael Debrah; George William Francis

    2015-01-01

    The exposure potential of children in nursery and kindergarten schools to metals in dust in the Kumasi Metropolis was studied. Dust samples from 20 selected schools were analyzed for heavy metal levels using atomic absorption spectrophotometry. The results showed that concentrations were in the range of below detection −9.710 μg/g for cobalt, below detection to 33.291 μg/g for chromium, below detection to 41.909 μg/g for lead, below detection to 1.383 μg/g for mercury, while cadmium levels we...

  3. A preorganized metalloreceptor for alkaline earth ions showing calcium versus magnesium selectivity in water: biological activity of selected metal complexes.

    Science.gov (United States)

    Amatori, Stefano; Ambrosi, Gianluca; Fanelli, Mirco; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Rossi, Patrizia

    2014-08-25

    The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (Malten = L) forms the highly stable [CuH(-2)L] species in water, in which the converging maltol oxygen atoms form an electron-rich area able to host hard metal ions. When considering the alkaline earth series (AE), the [Cu(H(-2)L)] species binds all metal ions, with the exception of Mg(2+), exhibiting the relevant property to discriminate Ca(2+) versus Mg(2+) at physiological pH 7.4; the binding of the AE metal is visible to the naked eye. The stability constant values of the trinuclear [AE{Cu(H(-2)L)}2](2+) species formed reach the maximum for Ca(2+) (log K=7.7). Ca(2+) also forms a tetranuclear [Ca{Cu(H(-2)L)}]2(4+) species at a high Ca(2+) concentration. Tri- and tetranuclear calcium complexes show blue- and pink-colored crystals, respectively. [Cu(H(-2)L)] is the most active species in inducing DNA alterations. The DNA damages are compatible with its hydrolytic cleavages.

  4. Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

    KAUST Repository

    Lee, Ming-Tsang

    2011-08-12

    In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment. © 2011 IOP Publishing Ltd.

  5. Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

    Science.gov (United States)

    Lee, Ming-Tsang; Lee, Daeho; Sherry, Alexander; Grigoropoulos, Costas P.

    2011-09-01

    In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment.

  6. PERSISTENT LEFT SUPERIOR VENACAVA

    Directory of Open Access Journals (Sweden)

    Devinder Singh

    2014-05-01

    Full Text Available A Persistent Left Superior Venacava (PLSVC is the most common variation of the thoracic venous system and rare congenital vascular anomaly and is prevalent in 0.3% of the population. It may be associated with other cardiovascular abnormalities including atrial septal defect, bicuspid aortic valve, coarctation of aorta, coronary sinus ostial atresia, and cor triatriatum. Incidental rotation of a dilated coronary sinus on echocardiography should raise the suspicion of PLSVC. The diagnosis should be confirmed by saline contrast echocardiography. Condition is usually asymptomatic. Here we present a rare case of persistent left superior vena cava presented in OPD with dyspnoea & palpitations.

  7. Superior Individual Selection of Sapindus mukorossi Based on Fruit and Seed Traits%基于种实性状的无患子优良单株选择

    Institute of Scientific and Technical Information of China (English)

    刁松锋; 邵文豪; 姜景民; 董汝湘; 肖可青

    2014-01-01

    Based on a specimen correlation matrix, with 102 eight-year-old Sapindus mukorossi Gaertn.individuals, the experi-ment was conducted to determine 12 major economic characteristics by the principal component analysis, including the weight per fruit, fruit finger, the volume of fruit, the thick of pericarp, the weight of pericarp, the weight per seed, seed finger, the volume of seed, the weight of kernel, the weight per kernel, the yield per plant, the saponin contents in the peep and the oil contents, in the kernel.Four factors (eigenvalues>1) were extracted from the converted data matrix with their cumulative contribution of 81.929%, including 47.727%of yield factor, 15.285%of oil factor yield, 10.206%of saponin factor and 8.711%of form factor.The superior individuals of six types are selected, in top 5%, including high-yield type, high-oil type, high-saponin type, high-yield and high-oil type, high-yield and high-saponin type, and com-pound type.The realized gains of superior individuals in each type are in 165%-311%.The principal component analysis can be used to select superior individual based on the main fruit traits and seed traits of S.mukorossi.The superior indi-viduals can be applied in production.%应用主成分分析法,从样本相关矩阵出发,以102株8年生无患子( Sapindus mukurossi Gaertn.)初选优株的12个主要种实性状(果实质量、果指数、果体积、果皮厚、果皮质量、种子质量、种指数、种体积、种仁质量、单株产量、果皮皂苷质量分数、种仁油脂质量分数)进行分析,以性状累积方差贡献率大于80%为标准,确定了4个反映无患子种实主要经济性状的主成分(特征值>1),即产量因子、油脂因子、产量皂苷因子和种实形态因子,其相应贡献率分别为47.271%、15.285%、10.206%和8.711%。通过对样本重要主成分值的比较分析,按5%入选率分别筛选出不同利用方向的6种类型

  8. Inhibitory projections from the ventral nucleus of the lateral lemniscus and superior paraolivary nucleus create directional selectivity of frequency modulations in the inferior colliculus: a comparison of bats with other mammals.

    Science.gov (United States)

    Pollak, George D; Gittelman, Joshua X; Li, Na; Xie, Ruili

    2011-03-01

    This review considers four auditory brainstem nuclear groups and shows how studies of both bats and other mammals have provided insights into their response properties and the impact of their convergence in the inferior colliculus (IC). The four groups are octopus cells in the cochlear nucleus, their connections with the ventral nucleus of the lateral lemniscus (VNLL) and the superior paraolivary nucleus (SPON), and the connections of the VNLL and SPON with the IC. The theme is that the response properties of neurons in the SPON and VNLL map closely onto the synaptic response features of a unique subpopulation of cells in the IC of bats whose inputs are dominated by inhibition. We propose that the convergence of VNLL and SPON inputs generates the tuning of these IC cells, their unique temporal responses to tones, and their directional selectivities for frequency modulated (FM) sweeps. Other IC neurons form directional properties in other ways, showing that selective response properties are formed in multiple ways. In the final section we discuss why multiple formations of common response properties could amplify differences in population activity patterns evoked by signals that have similar spectrotemporal features.

  9. Selective removal of heavy metal ions by disulfide linked polymer networks

    DEFF Research Database (Denmark)

    Ko, Dongah; Sung Lee, Joo; Patel, Hasmukh A.

    2017-01-01

    Heavy metal contaminated surface water is one of the oldest pollution problems, which is critical to ecosystems and human health. We devised disulfide linked polymer networks and employed as a sorbent for removing heavy metal ions from contaminated water. Although the polymer network material has...... a moderate surface area, it demonstrated cadmium removal efficiency equivalent to highly porous activated carbon while it showed 16 times faster sorption kinetics compared to activated carbon, owing to the high affinity of cadmium towards disulfide and thiol functionality in the polymer network. The metal...... sorption mechanism on polymer network was studied by sorption kinetics, effect of pH, and metal complexation. We observed that the metal ions―copper, cadmium, and zinc showed high binding affinity in polymer network, even in the presence of competing cations like calcium in water....

  10. Metal selectivity of Sargassum spp. and their alginates in relation to their alpha-L-guluronic acid content and conformation.

    Science.gov (United States)

    Davis, Thomas A; Llanes, Francisco; Volesky, Bohumil; Mucci, Alfonso

    2003-01-15

    The discovery of a consistent and unusual enrichment in homopolymeric alpha-L-guluronic acid G-blocks in alginates extracted from a suite of Sargassum brown algae is described in this study. 1H NMR spectroscopy was used to characterize these alginates which display homopolymeric guluronic acid block (G-block) frequency values (F(GG)) between 0.37 and 0.81. The presence of these G-blocks results in an enhanced selectivity for cadmium or calcium relative to monovalent ions such as sodium and the proton as well as smaller divalent ions such as magnesium. Results of competitive exchange experiments for the Cd-Ca-alginate system yield selectivity coefficient, K*(Cd)Ca, values between 0.43 +/- 0.10 and 1.32 +/- 0.02 for a range in F(GG) of 0.23 to 0.81. In contrast to the Cd-Ca-alginate system, the Mg-Ca-alginate and Mg-Cd-alginate systems yielded maximum values of K*(Mg)Ca (18.0 +/- 1.4) and K*(Mg)Cd (16.0 +/- 0.9) for the alginates extracted from Sargassum fluitans (F(GG) = 0.81; Cuba) and Sargassum thunbergii (F(GG) = 0.75; Korea), respectively. Selectivity studies with mixed-metal pair alginate systems highlight the importance of the specific macromolecular conformation of the alginate polymer in determining metal binding behavior in multiple-metal systems. Furthermore, they demonstrate the importance of the conformation of the alginate as it occurs within the tissue of Sargassum in determining the metal binding behavior of this algal biosorbent. The unique composition of the alginates present in species of Sargassum may represent a distinct advantage over other brown algal species when considering their implementation for the strategic removal of toxic heavy metals from contaminated and industrial wastewaters.

  11. Facile one-pot synthesis of spherical zinc sulfide-carbon nanocomposite powders with superior electrochemical properties as anode materials for Li-ion batteries.

    Science.gov (United States)

    Jang, Yong Seung; Kang, Yun Chan

    2013-10-21

    A novel and simple one-pot method of systematically synthesizing spherical metal sulfide-carbon composite powders is reported for the first time. The zinc sulfide-carbon composite is selected as the first target material. The prepared composite powders show superior electrochemical properties as anode materials for lithium-ion batteries.

  12. Trace metal content in mussels, Perna viridis L., obtained from selected seafood markets in a Metropolitan City.

    Science.gov (United States)

    Dumalagan, H G D; Gonzales, A C; Hallare, A V

    2010-04-01

    Mussels, Perna viridis L., obtained from three selected seafood markets in Metro Manila, were tested for metal content including cadmium, copper, lead, and zinc through atomic absorption spectrophotometry. Water samples from Bacoor Bay, Cavite, which supplies mussels to the market, were likewise subjected to similar metal analyses. Of the metals analyzed in the soft tissues of mussels, only copper and lead with highest obtained values of 10.4 mg/kg and 2.3 mg/kg, respectively exceeded the PEMSEA guideline for safe human consumption. Water samples collected from the harvest sites in Bacoor Bay showed high concentrations of cadmium (0.023 mg/L) and lead (0.25 mg/L) that exceeded the standards of DENR, ASEAN, and US EPA. Zinc, though detected in relatively high concentrations in both water (0.03 mg/L) and soft tissues (12.16-14.43 mg/kg) of mussels remained below the criteria set by the above-mentioned agencies. Overall, the present study indicates that mussels being sold in selected Metro Manila seafood markets were contaminated with metals, notably Cu and Pb, at concentrations that are unsafe for human consumption and thus, represents a health risk.

  13. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  14. Transition rates of selected metals determined in various types of teas (Camellia sinensis L. Kuntze) and herbal/fruit infusions.

    Science.gov (United States)

    Schulzki, Grit; Nüßlein, Birgit; Sievers, Hartwig

    2017-01-15

    Teas and raw materials used as ingredients of herbal and fruit infusions (HFI) were analysed by means of ICP-MS for their content of aluminium, arsenic, cadmium, copper, lead and mercury in the dry product and in the infusion. Samples of tea (Camellia sinensis L. Kuntze) were selected to include different origins, types (black, green), leaf grades (whole leaf, broken, fannings, dust) and manufacturing techniques (orthodox, "crush, tear, curl"). The selected HFI raw materials (chamomile, elderberries, fennel, hibiscus, mate, peppermint, rooibos and rose hip) cover the most important matrices (flower, fruit, seed, herb, leaf) and reflect the economic significance of these HFI materials in trade. Infusions were prepared under standardised conditions representing typical household brewing. Transition rates for the investigated metals vary significantly but are mostly well below 100%. We propose default transition rates for metals to avoid overestimation of exposure levels from tea/HFI consumption.

  15. Assessing the resistance and bioremediation ability of selected bacterial and protozoan species to heavy metals in metal-rich industrial wastewater

    Directory of Open Access Journals (Sweden)

    Kamika Ilunga

    2013-02-01

    Full Text Available Abstract Background Heavy-metals exert considerable stress on the environment worldwide. This study assessed the resistance to and bioremediation of heavy-metals by selected protozoan and bacterial species in highly polluted industrial-wastewater. Specific variables (i.e. chemical oxygen demand, pH, dissolved oxygen and the growth/die-off-rates of test organisms were measured using standard methods. Heavy-metal removals were determined in biomass and supernatant by the Inductively Couple Plasma Optical Emission Spectrometer. A parallel experiment was performed with dead microbial cells to assess the biosorption ability of test isolates. Results The results revealed that the industrial-wastewater samples were highly polluted with heavy-metal concentrations exceeding by far the maximum limits (in mg/l of 0.05-Co, 0.2-Ni, 0.1-Mn, 0.1-V, 0.01-Pb, 0.01-Cu, 0.1-Zn and 0.005-Cd, prescribed by the UN-FAO. Industrial-wastewater had no major effects on Pseudomonas putida, Bacillus licheniformis and Peranema sp. (growth rates up to 1.81, 1.45 and 1.43 d-1, respectively compared to other test isolates. This was also revealed with significant COD increases (p Pseudomonas putida demonstrated the highest removal rates of heavy metals (Co-71%, Ni-51%, Mn-45%, V-83%, Pb-96%, Ti-100% and Cu-49% followed by Bacillus licheniformis (Al-23% and Zn-53% and Peranema sp. (Cd-42%. None of the dead cells were able to remove more than 25% of the heavy metals. Bacterial isolates contained the genes copC, chrB, cnrA3 and nccA encoding the resistance to Cu, Cr, Co-Ni and Cd-Ni-Co, respectively. Protozoan isolates contained only the genes encoding Cu and Cr resistance (copC and chrB genes. Peranema sp. was the only protozoan isolate which had an additional resistant gene cnrA3 encoding Co-Ni resistance. Conclusion Significant differences (p Peranema sp. as a potential candidate for the bioremediation of heavy-metals in wastewater treatment, in addition to Pseudomonas

  16. A Selective Bioreduction of Toxic Heavy Metal Ions from Aquatic Environment by Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    A. M. Rahatgaonkar

    2008-01-01

    Full Text Available The need to remove or recover metal ions from industrial wastewater has been established in financial as well as environmental terms. This need has been proved financially in terms of cost saving through metal reuse or sale and environmentally as heavy metal toxicity can affect organisms throughout the food chain, including humans. Bioremediation of heavy metal pollution remains a major challenge in environmental biotechnology. Current removal strategies are mainly based on bioreduction of Co++, Ni++, Cu++ and Cd++ to their metallic forms by Saccharomyces cerevisiae in buffered aqueous solution. The rate of biotransformation was significantly influenced by pH of aqueous solution, concentration of biomass and hardness of water. All reaction conditions were optimized and maximum reduction of Co++, Cd++, Ni++ and Cu++ were observed as 80%, 63%, 50%, and 44% respectively. Unreacted Co++, Cd++, Ni++metal ions were extracted by 8-hydroxyquinoline and Cu++ by diethylthio carbamate in CHCl3 at different pH. Furthermore, the concentrations of unreacted metal ions were established spectrophotometrically.

  17. 1,2-Selective Hydrosilylation of Conjugated Dienes

    OpenAIRE

    Parker, Sarah Elizabeth

    2014-01-01

    Selective 1,2-hydrosilylation of 1,3-dienes is a challenging problem to solve for transition metal catalysis. Butadiene, specifically, would be a useful substrate because 3-butenylsilane products have promise as superior coupling reagents for hybrid organic/inorganic materials synthesis. In this thesis, we describe the first selective 1,2-hydrosilylation of conjugated dienes, including butadiene.

  18. Overcoming Statistical Complexity: Selective Coordination of Three Different Metal Ions to a Ligand with Three Different Coordination Sites.

    Science.gov (United States)

    Akine, Shigehisa; Matsumoto, Takashi; Nabeshima, Tatsuya

    2016-01-18

    In general, it is difficult to selectively introduce different metal ions at specific positions of a cluster-like structure. This is mainly due to statistical problems as well as the reversibility of the formation of coordination bonds. To overcome this statistical problem, we used a carefully designed ligand, H6 L, which can accommodate three different kinds of metal ions in three types of coordination sites. The complex [LNiZn2La](3+), which contains three different metals, was quantitatively obtained by a stepwise procedure, but different products were obtained when the metal ions were added in a different order. However, equilibration studies indicated that this complex was almost solely formed among 54 (=3×3×3H2) possible products upon heating; the formation efficiency (ca. 100%) was significantly higher than the statistical probability (2.47%). Such carefully designed ligands should be useful for the synthesis multimetallic systems, which are of interest because of the interplay between the different metals.

  19. Development of a thermodynamic data base for selected heavy metals; Entwicklung einer thermodynamischen Datenbasis fuer ausgewaehlte Schwermetalle

    Energy Technology Data Exchange (ETDEWEB)

    Hageman, Sven; Scharge, Tina; Willms, Thomas

    2015-07-15

    The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.

  20. Water-Stable Anionic Metal-Organic Framework for Highly Selective Separation of Methane from Natural Gas and Pyrolysis Gas.

    Science.gov (United States)

    Li, Lan; Wang, Xusheng; Liang, Jun; Huang, Yuanbiao; Li, Hongfang; Lin, Zujin; Cao, Rong

    2016-04-20

    A 3D water-stable anionic metal-organic framework [Zn4(hpdia)2]·[NH2(CH3)2]·3DMF·4H2O (FJI-C4) was constructed based on an elaborate phosphorus-containing ligand 5,5'-(hydroxyphosphoryl)diisophthalic acid (H5hpdia). FJI-C4 with narrow one-dimensional (1D) pore channels exhibits high selectivity of C3H8/CH4 and C2H2/CH4. It is the first time for the MOF which contains phosphorus for selective separation of methane from natural gas and pyrolysis gas.

  1. Advances in the extractive metallurgy of selected rare and precious metals

    Science.gov (United States)

    Hoffmann, James E.

    1991-04-01

    The broad field of extractive metallurgy, often perceived as an unimportant point of light in the universe of technology, has undergone significant, fundamental changes in the past 30 years. Improved extraction technologies now permit greater metal recovery, reduce the time that metal values are chemically locked up and diminish the economic impact of environmental regulations. Much of this accomplishment is due to the application of solvent extraction. As evidenced by improvements in the extraction of rare and precious metals, research in extractive metallurgy technology not only exists, but has achieved palpable results.

  2. Biosorption of environmentally relevant heavy metals on selected biomaterials for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ondruschka, J.; Bley, T. [Institut fuer Lebensmittel- und Bioverfahrenstechnik, TU Dresden, Bergstrasse 120, D-01069 Dresden (Germany)

    2003-05-01

    Biosorbents offer a realistic alternative to established processes for the elimination of heavy metals from wastewaters as well as for the recovery of valuable materials. This paper describes and compares the use of different biosorbents occurring as waste products from fermentation processes with regard to their suitability for the purification of metal-containing wastewaters. Besides the type and concentration of the metals the influence of the oxidation state of the cations and of the pH value of the system on the sorption capacity of the microorganisms are investigated. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  3. Heavy metal uptake by selected marsh plant species grown in hydroponic cultures

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.R.; Sturgis, T.C.; Landin, M.C.

    1975-01-01

    Eight marsh plant species (Cyperus esculentus, Scirpus validus, Spartina patens, Scirpus robustus, Triglochin maritima, Distichlis spicata, Spartina alterniflora, and Spartina foliosa) were grown under greenhouse conditions in chemically controlled nutrient solutions. Heavy metals (zinc, cadmium, nickel, chromium, and lead) were added to the nutrient solutions at levels of 0, 0.5, and 1.0 mg/l. Plant parts (leaves, rhizomes, tubers, and roots) were harvested separately for each species and analyzed for heavy metal content. The concentration and plant uptake of heavy metals in each plant species will be discussed.

  4. Reversible structural transformations in a Co(II)-based 2D dynamic metal-organic framework showing selective solvent uptake

    Indian Academy of Sciences (India)

    Sanjog S Nagarkar; Sujit K Ghosh

    2015-04-01

    A Co(II)-based two-dimensional (2D) metal-organic framework (MOF) [Co(pca)(bdc)0.5(H2O)2] (1) {pca = pyrazine carboxylic acid, and bdc = 1,4-benzene dicarboxylic acid} was synthesized solvothermally. The compound loses the coordinated lattice water molecules on heating which is accompanied by solidstate structural transformation to yield dehydrated phase [Co(pca)(bdc)0.5] (1′). The hydrated structure can be regained by exposing 1′ to water vapour (1′′). These reversible solid-state structural transformations are accompanied by a visible colour change in the material. The dehydrated compound also shows highly selective water uptake over other solvents like MeOH, EtOH, THF. This selective water uptake can be ascribed to the high affinity of polar water molecule towards the open metal site created on heating. The present report provides important insights into the reversible structural transformations observed due to variable coordination number of the central metal ion and transformability of the framework. The selective water uptake over alcohols along with visible colour change demonstrates the potential of the present compound in bio-alcohol purification.

  5. Ligand design for site-selective metal coordination: synthesis of transition-metal complexes with η{sup 6}-coordination of the central ring of anthracene

    Energy Technology Data Exchange (ETDEWEB)

    Karslyan, Eduard E.; Borissova, Alexandra O.; Perekalin, Dmitry S. [Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    2017-05-08

    A polycyclic aromatic ligand for site-selective metal coordination was designed by using DFT calculations. The computational prediction was confirmed by experiments: 2,3,6,7-tetramethoxy-9,10-dimethylanthracene initially reacts with [(C{sub 5}H{sub 5})Ru(MeCN){sub 3}]BF{sub 4} to give the kinetic product with a [(C{sub 5}H{sub 5})Ru]{sup +} fragment coordinated at the terminal ring, which is then transformed into the thermodynamic product with coordination through the central ring. These isomeric complexes have markedly different UV/Vis spectra, which was explained by analysis of the frontier orbitals. At the same time, the calculations suggest that electrostatic interactions are mainly responsible for the site selectivity of the coordination. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Sol-Gel Synthesis and Characterization of Selected Transition Metal Nano-Ferrites

    Directory of Open Access Journals (Sweden)

    Aurelija GATELYTĖ

    2011-09-01

    Full Text Available In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12, yttrium perovskite ferrite (YFeO3, cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively powders by an aqueous sol-gel processes are investigated. The metal ions, generated by dissolving starting materials of transition metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the transition metal ferrite ceramics. The phase purity of synthesized nano-compounds was characterized by infrared spectroscopy (IR and powder X-ray diffraction analysis (XRD. The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM.http://dx.doi.org/10.5755/j01.ms.17.3.598

  7. Toxic effects of selected heavy metals on unadapted populations of Vorticella convallaria var similis

    Energy Technology Data Exchange (ETDEWEB)

    Sartory, D.P.; Lloyd, B.J.

    1976-01-01

    The presence of large amounts of heavy metals in sewages may cause sever disruption of the biologica1processes involved in sewage treatment, and thus a decline in the quality of the effluent produced. Unadapted populations of Vorticella convallaria var similis, a sessile peritrich protozoan found abundantly in healthy rivers, activated sludge, percolating filters and slow sand filters, were subjected to a range of concentrations of three common pollutant metals. It was found that these populations were killed by concentrations of, and above, 0.0005 mg/l of the free metal ion of either lead or mercury. Colonies were also killed by concentrations of, and above, 0.075 mg/l of the free metal ion of zinc. 12 hr 50% lethal doses were calculated, and for V. convallaria var similis were found to be 0.0036 mg/l. for lead, 0.005 mg/l for mercury and 0.29 mg/l for zinc.

  8. A note on the concentrations and bioavailability of selected metals in ...

    African Journals Online (AJOL)

    2005-10-04

    Oct 4, 2005 ... Keywords: sediments, metals, bioavailability, sediment composition, Richards Bay Harbour ... terns characteristic of estuarine and near-shore marine environ- ments ... a settling tube to measure settling velocities (sand fraction.

  9. Planarians in toxicology. Responses of asexual Dugesia dorotocephala to selected metals

    Energy Technology Data Exchange (ETDEWEB)

    Kapu, M.M.; Schaeffer, D.J. (Univ. of Illinois, Urbana (United States))

    1991-08-01

    The planarian Dugesia dorotocephala is a freshwater invertebrate found in unpolluted flowing surface waters. Planarians have a sensitive nervous system with synapses and true brain and evidence these in a variety of social and response behaviors. The inclusion of planarians in a screening battery would provide improved sensitivity in detecting toxicity because planarians commonly respond to lower levels of contamination than do other species. Numerous toxicity test have been conducted to determine the acute and chronic effects of toxicants to provide data necessary for the development of water quality criteria. The appropriateness of Illinois water quality standards for metals was investigated using a 1-hr behavioral test based on the responses of the planarian D. dorotocephala. One possible difficulty with water quality standards for metals is that the standard for each metal is usually established without regard to the effects of other metals present in the receiving water.

  10. Risk assessment of mineral and heavy metal content of selected tea products from the Ghanaian market.

    Science.gov (United States)

    Nkansah, Marian Asantewah; Opoku, Francis; Ackumey, Abiathar Abraham

    2016-06-01

    Food consumption is the most likely route of human exposure to metals. Tea (Camellia sinensis L.) is among the most widely consumed non-alcoholic beverages. Concentrations of heavy metals and minerals in tea from 15 different brands in Kumasi, Ghana were measured to assess the health risk associated with their consumption. The mineral and metal contents (Fe, Cu, Zn, Pb, As, Cd) were analyzed using atomic absorption spectrophotometer (Z-8100 polarized Zeeman). The results revealed that the mean concentrations were in the order: Ca > Fe > As > Cd > Zn > Pb. The average contents of Ca, Fe, Zn, Pb, Cd, and As in the samples were 94.08, 6.15, 0.20, 0.16, 0.36, and 1.66 mg/kg, respectively. All the minerals and heavy metals were below the maximum permissible limits stipulated by the World Health Organization (WHO) and US Pharmacopeia (USP). Metal-to-metal correlation indicated strong correlations between As/Zn, Cd/Zn, Cd/As, and Pb/As pairs. Factor analysis demonstrated a clear separation between minerals, grouped on one side, and heavy metals, clustered on another side. Both the target hazard quotient (THQ) and hazard index (HI) levels in green tea were far below 1, suggesting that consumption of green tea should pose no potential risk to human health. However, carcinogenic risk levels for arsenic were high; R > 10(-6). The results showed that residents in Kumasi consume tea could be at risk from exposure to these heavy metals and minerals.

  11. Passage of selected heavy metals from Sphaerotilus (bacteria: Chlamydobacteriales) to Paramecium caudatum (protozoa: Ciliata)

    Energy Technology Data Exchange (ETDEWEB)

    Mansouri-Aliabadi, M.; Sharp, R.E.

    1985-01-01

    Sphaerotilus, a bacterium occurring in polluted waters, was found to take up Zn, Pb, Ni and Mn. Metal-containing cultures of this bacterium were employed to feed the protozoan Paramecium caudatum, and analytical results revealed the accumulation of Zn, Pb and Ni. Since Sphaerotilus wa the only food source for paramecia during this study, the results indicate that trace amounts of metal were passed from bacteria to protozoa in a predator-prey relationship.

  12. Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas

    2008-01-01

    The removal of trace acetylene from ethylene is performed industrially by palladium hydrogenation catalysts ( often modified with silver) that avoid the hydrogenation of ethylene to ethane. In an effort to identify catalysts based on less expensive and more available metals, density functional...... calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel- zinc alloys as alternatives. Experimental studies demonstrated that these alloys...

  13. Hydrogen evolution activity and electrochemical stability of selected transition metal carbides in concentrated phosphoric acid

    DEFF Research Database (Denmark)

    Tomás García, Antonio Luis; Jensen, Jens Oluf; Bjerrum, Niels J.

    2014-01-01

    Alternative catalysts based on carbides of Group 5 (niobium and tantalum) and 6 (chromium, molybdenum and tungsten) metals were prepared as films on the metallic substrates. The electrochemical activities of these carbide electrodes towards the hydrogen evolution reaction (HER) in concentrated......, attributable to the different electronic structures. Tungsten carbide among the studied electrode samples exhibited the highest HER activity. Upon anodic potential scans in the presence of oxygen, chromium, tantalum and tungsten carbides displayed passivation due to the formation of stable surface layers...

  14. Influence of clinoptilolite rock on chemical speciation of selected heavy metals in sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Sprynskyy, M.; Kosobucki, P.; Kowalkowski, T. [Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun (Poland); Buszewski, B. [Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Torun (Poland)], E-mail: bbusz@chem.uni.torun.pl

    2007-10-22

    The chemical speciation of Cd, Cu, Pb, Cr and Ni in Torun municipal sewage sludge is investigated with addition of a natural sorbent (clinoptilolite rock). The total contents of the heavy metals in the sludge are substantially lower than the corresponding limits established by European or Polish legislation excepting nickel only. But the metals concentrations excepting lead exceed significantly the natural background (average contents in soils and in the Earth's crust) in dozens. Application of the sequential chemical extraction indicated that the metals in the sewage sludge are bound mainly (over 50%) in the residual fraction. The metals form the following order by parts of the mobile form: Ni > Cd >> Cr > Cu >> Pb. Addition of the clinoptilolite to the sludge leads to the metals contents fall in all four fractions of the sequential procedure. Concentrations of mobile forms of cadmium, chromium, copper and nickel decrease by 87, 64, 35 and 24%, respectively, as a result of addition of 9.09% of the clinoptilolite. The total decreases of the metals amount after 9.09% clinoptilolite addition to the sludge are around 11, 15, 25, 41 and 51% for copper, nickel, chromium, cadmium and lead, respectively.

  15. Distribution of selected heavy metals in skin and muscle of five tropical marine fishes.

    Science.gov (United States)

    Singh, J G; Chang-Yen, I; Stoute, V A; Chatergoon, L

    1991-01-01

    An investigation was carried out to determine the effect of tissue type, tissue location and size of fish on the heavy metal levels of five species of fish found in the marine environment of the tropical island of Trinidad. The study was conducted with the fish species Lutjanus synagris, Micropogon furnieri, Cynoscion leiarchus, Caranx hippos and Scomberomorus brasiliensis, and focused on the muscle and skin tissues of the fillet of these fish. The metals Fe, Zn, Cu, Ni, Pb, Cd and Cr were analysed by atomic absorption spectrophotometry after acid digestion of the tissues, but only Fe, Zn and Cu were detected. Skin tissue showed elevated levels of metals in comparison with muscle tissue, and significant differences in metal levels with respect to tissue location in skin, and varying effects of size on both muscle and skin metal levels in the different species, were found. These results emphasize the need for careful sampling of tissue in these fish species if reliable data on heavy metal levels are to be generated.

  16. Assessment of toxic metals in wheat crops grown on selected soils, irrigated by different water sources

    Directory of Open Access Journals (Sweden)

    Zeid A. Al-Othman

    2016-11-01

    Full Text Available We describe a comparative study of the concentration of different metals (e.g., Cd, Pb, As, Ni, Cu, Zn, Mn, and Cr in various parts of wheat plants (e.g., roots, stem, leaves and seeds collected at several locations in Khyber Pukhtoon Khaw, Pakistan. The wheat crop in these areas was irrigated using different irrigation sources, including rain, tube well, river, and canal. In wheat samples, the concentration of metals was analyzed using an atomic absorption spectrophotometer. Among the various parts of the plant, the roots had the highest levels of heavy metals, followed by the vegetative parts. By comparison, the seeds and grains had the lowest levels of heavy metals. The levels of heavy metals in all of the studied areas were not significantly localized to any particular area. The general order for the accumulation of studied metals in wheat was found to be Mn > Zn > Cu > Ni > Cr > As > Pb > Cd.

  17. Distribution and Potential Mobility of Selected Heavy Metals in a Fluvial Environment Under the Influence of Tanneries

    Directory of Open Access Journals (Sweden)

    Rodrigues M. L. K.

    2013-04-01

    Full Text Available In this study we evaluated the occurrence of heavy metals in a fluvial environment under the influence of tanneries – the Cadeia and Feitoria rivers basin (RS, south Brazil, highlighting the distribution and potential mobility of the selected elements. Every three months, over one year-period, selected heavy metals and ancillary parameters were analyzed in water and sediment samples taken at ten sites along the rivers. Water analyses followed APHA recommendations, and sediment analyses were based on methods from USEPA (SW846 and European Community (BCR sequential extraction. The determinations were performed by ICP/OES, except for Hg (CV/ETA. Statistical factor analysis was applied to water and sediment data sets, in order to obtain a synthesis of the environmental diagnosis. The results revealed that water quality decreased along the rivers, and mainly on the dry period (January, showing the influence of tannery plants vicinity and flow variations. Except for Fe, Al, and eventually Mn, heavy metal contents in water were in agreement with Brazilian standards. Concerning sediments, Al, Cu, Fe, Ni, Mn, Ti, and Zn concentrations appeared to reflect the base levels, while Cr and Hg were enriched in the deposits from the lower part of the basin. The partition of heavy metals among the sediment geochemical phases showed higher mobility of Mn along the sampling sites, followed by Cr in the lower reach of the basin, most affected by tanneries. Since Cr was predominantly associated to the oxidizable fraction, its potential mobilization from contaminated sediments would be associated to redox conditions. The detection of Hg in the tissue of a bottom-fish species indicated that the environmental conditions are apparently favoring the remobilization of this metal from contaminated sediments.

  18. Air Superiority Fighter Characteristics.

    Science.gov (United States)

    1998-06-05

    many a dispute could have been deflated into a single paragraph if the disputants had just dared to define their terms.7 Aristotle ...meaningful. This section will expand on some key ideology concepts. The phrase "air superiority fighter" may bring to mind visions of fighter... biographies are useful in garnering airpower advocate theories as well as identifying key characteristics. Air campaign results, starting with World

  19. Site-selective adsorption of protein induced by a metal pattern on a poly(ethylene terephthalate) surface.

    Science.gov (United States)

    Cao, Jiali; Wu, Zhongkui; Li, Shaoying; Tang, Hongxiao; Mei, Qilin

    2013-11-01

    A novel technique for inducing site-selective adsorption of protein through constructing metal patterns on flexible poly(ethylene terephthalate) surfaces is presented. The substrates were first modified by vacuum ultraviolet (VUV) irradiation through a photomask to introduce regions with different functional groups. Then the designed metal patterns were constructed on the surfaces of VUV-treated substrates. The surface rearrangement was effectively prevented by constructing silver patterns on poly(ethylene terephthalate) surfaces, thus significantly improving the stability and selectivity of protein adsorption on the surfaces. Moreover, the protein-repulsive layer further reinforced the effect. Finally, protein patterns were successfully obtained. As confirmed by fluorescence microscope, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and static water contact angle measurement, the protein patterns possess both excellent selectivity and high fidelity. Feature size of the protein patterns surrounded by a protein-repulsive layer was exactly the same as that of the photomask. And the grain sizes of silver particles were approximately 50 nm. This work could potentially be used in various fields such as biomedicine, bioelectronic components, and tissue repair and replacement, where selective adsorption of protein is desired.

  20. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  1. Assessment of possible control of selected operational properties of metal-ceramic foams

    Directory of Open Access Journals (Sweden)

    J. Grabian

    2010-01-01

    Full Text Available Effective use of metal foams, an increasingly popular group of machine structural materials, often requires that their properties be adjusted to customer needs. The growing popularity of foams is due to their specific properties, i.e. capability of absorbing the impact and explosion energy, increasing the stiffness of structural components such as panels of closed profiles, ability to damp vibrations, relatively good thermal insulation, dispersion of electromagnetic waves, resistance to high temperature and others. One of the operational properties of metal foams that is essential for their use in various structures is the resistance to single-axial static compression.Initial studies aimed at the determination of how metal foam behaves when statically compressed. Foam samples were made by blowing gas into liquid metal. The composition of metal foam (AlSi11 was differentiated by introducing ceramic particles SiC. By changing technological parameters of the foaming process we could affect the size of gaseous bubbles and their homogeneity. By comparing the structure of foams and their properties we found significant differences in the curve x = f(P of foam sample affected by the force (P. It has been proved that one operational property, namely the resistance to compression, can be indirectly controlled, that is its determined specific structure can be obtained by maintaining specific technological parameters.

  2. Accumulation of Heavy Metals in Crayfish and Fish from Selected Czech Reservoirs

    Directory of Open Access Journals (Sweden)

    Iryna Kuklina

    2014-01-01

    Full Text Available To evaluate the accumulation of aluminium, cadmium, chromium, copper, lead, mercury, nickel, and zinc in crayfish and fish organ tissues, specimens from three drinking water reservoirs (Boskovice, Landštejn, and Nová Říše and one contaminated site (Darkovské moře in the Czech Republic were examined. Crayfish hepatopancreas was confirmed to be the primary accumulating site for the majority of metals (Cu > Zn > Ni > Cd > Cr, while Hg and Cr were concentrated in abdominal muscle, and Al and Pb were concentrated in gill. Metals found in Nová Říše specimens included Cu > Zn > Ni and those found in Boskovice included Zn > Hg > Cr. Cd concentrations were observed only in Landštejn specimens, while contaminated Darkovské moře specimens showed the highest levels of accumulation (Cu > Al > Zn > Pb. The majority of evaluated metals were found in higher concentrations in crayfish: Cu > Al > Zn > Ni > Cr > Cd > Pb, with Hg being the only metal accumulating higher in fish. Due to accumulation similarities of Al in crayfish and fish gill, differences of Hg in muscle, and features noted for the remaining metals in examined tissues, biomonitoring should incorporate both crayfish and fish to produce more relevant water quality surveys.

  3. Concentrations and solubility of selected trace metals in leaf and bagged black teas commercialized in Poland

    Directory of Open Access Journals (Sweden)

    L. Polechońska

    2015-09-01

    Full Text Available The objective of this study was to determine the concentrations of heavy metals in bagged and leaf black teas of the same brand and evaluate the percentage transfer of metals to tea infusion to assess the consumer exposure. Ten leaf black teas and 10 bagged black teas of the same brand available in Poland were analyzed for Zn, Mn, Cd, Pb, Ni, Co, Cr, Al, and Fe concentrations both in dry material and their infusion. The bagged teas contained higher amounts of Pb, Mn, Fe, Ni, Al, and Cr compared with leaf teas of the same brand, whereas the infusions of bagged tea contained higher levels of Mn, Ni, Al, and Cr compared with leaf tea infusions. Generally, the most abundant trace metals in both types of tea were Al and Mn. There was a wide variation in percentage transfer of elements from the dry tea materials to the infusions. The solubility of Ni and Mn was the highest, whereas Fe was insoluble and only a small portion of this metal content may leach into infusion. With respect to the acceptable daily intake of metals, the infusions of both bagged and leaf teas analyzed were found to be safe for human consumption.

  4. The effect of materials selection on metals reduction in propylene glycol methyl ether acetate, PGMEA

    Science.gov (United States)

    Entezarian, Majid; Geiger, Bob

    2016-03-01

    The trend in microelectronics fabrication is to produce nano-features measuring down to 10 nm and finer. The PPT levels of organic and inorganic contaminants in the photoresist, solvent and cleaning solutions are becoming a major processing variable affecting the process capability and defectivity. The photoresist usually contains gels, metals, and particulates that could interfere with the lithography process and cause microbridging defects. Nano filters of 5 nm polypropylene, 5 nm polyethylene, and 10 nm natural nylon were used to filter propylene glycol methyl ether acetate PGMEA containing 50 ppb of Na, Mg, Al, Ca, Cr, Mn, Fe, Cu, Zn, and Pb. All filters were effective in removing trivalent Al, Cr, and Fe metals indicating the mechanism for their removal as mechanical sieving. However, the nylon was also very effective in removing the divalent metals showing adsorptive properties. Furthermore, the metal removal of the nylon membrane was studied as a function of surface chemistry. Natural and charged 40 nm nylon membranes were tested and found that charged nylon is more effective for metal removal.

  5. Recycling Potentials of Critical Metals-Analyzing Secondary Flows from Selected Applications

    Directory of Open Access Journals (Sweden)

    Till Zimmermann

    2014-03-01

    Full Text Available Metal mobilization in general, as well as the number of metals used in products to increase performance and provide sometimes unique functionalities, has increased steadily in the past decades. Materials, such as indium, gallium, platinum group metals (PGM, and rare earths (RE, are used ever more frequently in high-tech applications and their criticality as a function of economic importance and supply risks has been highlighted in various studies. Nevertheless, recycling rates are often below one percent. Against this background, secondary flows of critical metals from three different end-of-life products up to 2020 are modeled and losses along the products’ end-of-life (EOL chain are identified. Two established applications of PGM and RE–industrial catalysts and thermal barrier coatings–and CIGS photovoltaic cells as a relatively new product have been analyzed. In addition to a quantification of future EOL flows, the analysis showed that a relatively well working recycling system exists for PGM-bearing catalysts, while a complete loss of critical metals occurs for the other applications. The reasons include a lack of economic incentives, technologically caused material dissipation and other technological challenges.

  6. Nutritional composition and heavy metal content of selected fruits in Nigeria

    Directory of Open Access Journals (Sweden)

    Koleayo Oluwafemi Omoyajowo

    2017-06-01

    Full Text Available Despite the nutritional benefits obtained from fruit consumption, the presence of heavy metals accompanying it from the environment draws scientific concerns as these affect human health. The aim of this study is to determine nutritional composition and heavy metal content of some commonly consumed fruits (apple, watermelon and sweet orange in Nigeria. Atomic absorption spectrophotometry was used to determine nickel, cadmium, chromium, lead and copper present in fruits. The results obtained show that the three fruit varieties contained considerable nutritional value that may meet body needs. Additionally, there was no significant difference in heavy metal concentrations of the fruits based on different locations (ANOVA F. test >0.05. This study posits that all the fruit varieties had the heavy metals within world health organisation (WHO permissible limit except apples. Apples sampled for different locations had nickel and chromium levels above the WHO permissible limits. Based on the observations in this study, there is a need for continuity of heavy metals inspection in agricultural products so as to prevent contamination and secure human safety.

  7. Rationally tuned micropores within enantiopure metal-organic frameworks for highly selective separation of acetylene and ethylene.

    Science.gov (United States)

    Xiang, Sheng-Chang; Zhang, Zhangjing; Zhao, Cong-Gui; Hong, Kunlun; Zhao, Xuebo; Ding, De-Rong; Xie, Ming-Hua; Wu, Chuan-De; Das, Madhab C; Gill, Rachel; Thomas, K Mark; Chen, Banglin

    2011-02-22

    Separation of acetylene and ethylene is an important industrial process because both compounds are essential reagents for a range of chemical products and materials. Current separation approaches include the partial hydrogenation of acetylene into ethylene over a supported Pd catalyst, and the extraction of cracked olefins using an organic solvent; both routes are costly and energy consuming. Adsorption technologies may allow separation, but microporous materials exhibiting highly selective adsorption of C(2)H(2)/C(2)H(4) have not been realized to date. Here, we report the development of tunable microporous enantiopure mixed-metal-organic framework (M'MOF) materials for highly selective separation of C(2)H(2) and C(2)H(4). The high selectivities achieved suggest the potential application of microporous M'MOFs for practical adsorption-based separation of C(2)H(2)/C(2)H(4).

  8. Selective etching of metallic single-wall carbon nanotubes with hydrogen plasma.

    Science.gov (United States)

    Hassanien, A; Tokumoto, M; Umek, P; Vrbanič, D; Mozetič, M; Mihailović, D; Venturini, P; Pejovnik, S

    2005-02-01

    We present Raman scattering and scanning tunnelling microscopy (STM) measurements on hydrogen plasma etched single-wall carbon nanotubes (SWNTs). Interestingly, both the STM and Raman spectroscopy show that the metallic SWNTs are dramatically altered and highly defected by the plasma treatment. In addition, structural characterizations show that metal catalysts are detached from the ends of the SWNT bundles. For semiconducting SWNTs we observe no feature of defects or etching along the nanotubes. Raman spectra in the radial breathing mode region of plasma-treated SWNT material show that most of the tubes are semiconducting. These results show that hydrogen plasma treatment favours etching of metallic nanotubes over semiconducting ones and therefore could be used to tailor the electronic properties of SWNT raw materials.

  9. Synthesis of Inorganic Nanocomposites by Selective Introduction of Metal Complexes into a Self-Assembled Block Copolymer Template

    Directory of Open Access Journals (Sweden)

    Hiroaki Wakayama

    2015-01-01

    Full Text Available Inorganic nanocomposites have characteristic structures that feature expanded interfaces, quantum effects, and resistance to crack propagation. These structures are promising for the improvement of many materials including thermoelectric materials, photocatalysts, and structural materials. Precise control of the inorganic nanocomposites’ morphology, size, and chemical composition is very important for these applications. Here, we present a novel fabrication method to control the structures of inorganic nanocomposites by means of a self-assembled block copolymer template. Different metal complexes were selectively introduced into specific polymer blocks of the block copolymer, and subsequent removal of the block copolymer template by oxygen plasma treatment produced hexagonally packed porous structures. In contrast, calcination removal of the block copolymer template yielded nanocomposites consisting of metallic spheres in a matrix of a metal oxide. These results demonstrate that different nanostructures can be created by selective use of processes to remove the block copolymer templates. The simple process of first mixing block copolymers and magnetic nanomaterial precursors and then subsequently removing the block copolymer template enables structural control of magnetic nanomaterials, which will facilitate their applicability in patterned media, including next-generation perpendicular magnetic recording media.

  10. Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

    Directory of Open Access Journals (Sweden)

    Ludovic F. Dumee

    2014-08-01

    Full Text Available Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm as well as the sintering pressure (5–20 ton·m−2 and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.

  11. Screening metal-organic frameworks for selective noble gas adsorption in air: effect of pore size and framework topology.

    Science.gov (United States)

    Parkes, Marie V; Staiger, Chad L; Perry, John J; Allendorf, Mark D; Greathouse, Jeffery A

    2013-06-21

    The adsorption of noble gases and nitrogen by sixteen metal-organic frameworks (MOFs) was investigated using grand canonical Monte Carlo simulation. The MOFs were chosen to represent a variety of net topologies, pore dimensions, and metal centers. Three commercially available MOFs (HKUST-1, AlMIL-53, and ZIF-8) and PCN-14 were also included for comparison. Experimental adsorption isotherms, obtained from volumetric and gravimetric methods, were used to compare krypton, argon, and nitrogen uptake with the simulation results. Simulated trends in gas adsorption and predicted selectivities among the commercially available MOFs are in good agreement with experiment. In the low pressure regime, the expected trend of increasing adsorption with increasing noble gas polarizabilty is seen. For each noble gas, low pressure adsorption correlates with several MOF properties, including free volume, topology, and metal center. Additionally, a strong correlation exists between the Henry's constant and the isosteric heat of adsorption for all gases and MOFs considered. Finally, we note that the simulated and experimental gas selectivities demonstrated by this small set of MOFs show improved performance compared to similar values reported for zeolites.

  12. Co-selection of antibiotic and metal(loid) resistance in gram-negative epiphytic bacteria from contaminated salt marshes.

    Science.gov (United States)

    Henriques, Isabel; Tacão, Marta; Leite, Laura; Fidalgo, Cátia; Araújo, Susana; Oliveira, Cláudia; Alves, Artur

    2016-08-15

    The goal of this study was to investigate co-selection of antibiotic resistance in gram-negative epiphytic bacteria. Halimione portulacoides samples were collected from metal(loid)-contaminated and non-contaminated salt marshes. Bacterial isolates (n=137) affiliated with Vibrio, Pseudomonas, Shewanella, Comamonas, Aeromonas and with Enterobacteriaceae. Vibrio isolates were more frequent in control site while Pseudomonas was common in contaminated sites. Metal(loid) and antibiotic resistance phenotypes varied significantly according to site contamination, and multiresistance was more frequent in contaminated sites. However, differences among sites were not observed in terms of prevalence or diversity of acquired antibiotic resistance genes, integrons and plasmids. Gene merA, encoding mercury resistance, was only detected in isolates from contaminated sites, most of which were multiresistant to antibiotics. Results indicate that metal(loid) contamination selects for antibiotic resistance in plant surfaces. In salt marshes, antibiotic resistance may be subsequently transferred to other environmental compartments, such as estuarine water or animals, with potential human health risks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. A review of composite and metallic bipolar plates in proton exchange membrane fuel cell: Materials, fabrication, and material selection

    Science.gov (United States)

    Taherian, Reza

    2014-11-01

    Proton exchange membrane (PEM) fuel cells offer exceptional potential for a clean, efficient, and reliable power source. The bipolar plate (BP) is a key component in this device, as it connects each cell electrically, supplies reactant gases to both anode and cathode, and removes reaction products from the cell. BPs have primarily been fabricated from high-density graphite, but in recent years, much attention has been paid to develop the cost-effective and feasible alternative materials. Recently, two different classes of materials have been attracted attention: metals and composite materials. This paper offers a comprehensive review of the current researches being carried out on the metallic and composite BPs, covering materials and fabrication methods. In this research, the phenomenon of ionic contamination due to the release of the corrosion products of metallic BP and relative impact on the durability as well as performance of PEM fuel cells is extensively investigated. Furthermore, in this paper, upon several effective parameters on commercialization of PEM fuel cells, such as stack cost, weight, volume, durability, strength, ohmic resistance, and ionic contamination, a material selection is performed among the most common BPs currently being used. This material selection is conducted by using Simple Additive Weighting Method (SAWM).

  14. Serum Concentrations of Selected Heavy Metals in Patients with Alcoholic Liver Cirrhosis from the Lublin Region in Eastern Poland

    Directory of Open Access Journals (Sweden)

    Andrzej Prystupa

    2016-06-01

    Full Text Available According to the WHO report, alcohol is the third most significant health risk factor for the global population. There are contrary reports about heavy metals concentrations in patients with alcoholic liver cirrhosis. The aim of this study was to investigate serum concentrations of selected heavy metals in patients with alcoholic liver cirrhosis living in the eastern part of Poland according to cirrhosis stage. The participants came from various hospitals of the Lublin region were enrolled. The study group included 46 male and 16 female patients. The control group consisted of 18 healthy individuals without liver disease. High Performance Ion Chromatography was used to determine the concentrations of metal ions (Cd, Zn, Cu, Ni, Co, Mn, and Pb in serum samples. The concentrations of copper, zinc, nickel, and cobalt were found to be significantly lower in patients with alcoholic liver cirrhosis compared to the control group. The serum concentration of cadmium was significantly higher in patients with advanced alcoholic liver cirrhosis compared to the control group. We hypothesize that disorders of metabolism of heavy metals seem to be the outcome of impaired digestion and absorption, which are common in cirrhosis, improper diet, environmental and occupational exposure.

  15. Determination of heavy metals in dust from selected nursery and kindergarten classrooms within the Kumasi metropolis of Ghana

    Directory of Open Access Journals (Sweden)

    Marian Asantewah Nkansah

    2015-12-01

    Full Text Available The exposure potential of children in nursery and kindergarten schools to metals in dust in the Kumasi Metropolis was studied. Dust samples from 20 selected schools were analyzed for heavy metal levels using atomic absorption spectrophotometry. The results showed that concentrations were in the range of below detection −9.710 μg/g for cobalt, below detection to 33.291 μg/g for chromium, below detection to 41.909 μg/g for lead, below detection to 1.383 μg/g for mercury, while cadmium levels were below detection for all samples. The mean levels of metals therefore decreased in the order: Cr > Pb > Co > Hg and Cd. Geographical variation correlated with heavy metal load. Health risk assessment using hazard quotient (HQ and hazard index (HI calculations indicated that ingestion contributed more to exposure than dermal contact. However, the values obtained by HQ and HI do not pose any immediate health risk but the cumulative effect is a matter of concern.

  16. Influence of DC plasma modification on the selected properties and the geometrical surface structure of polylactide prior to autocatalytic metallization

    Energy Technology Data Exchange (ETDEWEB)

    Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Rytlewski, Piotr [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland); Tracz, Adam [Centre for Molecular and Macromolecular Studies of the Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź (Poland); Żenkiewicz, Marian [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland)

    2015-03-01

    The paper presents the results of studies to determine the applicability of plasma modification in the process of polylactide (PLA) surface preparation prior to the autocatalytic metallization. The polylactide plasma modification was carried out in an oxygen or nitrogen chemistry. The samples were tested with the following methods: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and electron spectrophotometry (XPS). Scanning electron microscopy and atomic force microscopy images were demonstrated. The results of surface free energy calculations, performed based on the results of the contact angle measurements have been presented. The results of the qualitative (degree of oxidation or nitridation) and quantitative analysis of the chemical composition of the polylactide surface layer have also been described. The results of the studies show that the DC plasma modification performed in the proposed condition is a suitable as a method of surface preparation for the polylactide metallization. - Highlights: • We modified polylactide surface layer with plasma generated in oxygen or nitrogen. • We tested selected properties and surface structure of modified samples. • DC plasma modification can be used to prepare the PLA surface for metallization. • For better results metallization should be preceded by sonication process.

  17. Metal adsorption capabilities of clinoptilolite and selected strains of bacteria from mine water

    Science.gov (United States)

    Mamba, B. B.; Dlamini, N. P.; Nyembe, D. W.; Mulaba-Bafubiandi, A. F.

    Small-scale mining has socio-economic advantages such as the reduction of unemployment and the general improvement of the economy. However, these operations if not properly managed or controlled have a potential to cause environmental damage, particularly with respect to the contamination of groundwater and water supplies that are not distant from where these mining activities take place. This paper focuses on metal removal from water contaminated by heavy metals emanating from small-scale mining operations using clinoptilolite and bacteria. Removal of As, Ni, Mn, Au, Co, Cu and Fe was carried out on mine water samples using original and HCl-activated (in 0.02 M and 0.04 M) natural clinoptilolite and bacterial strains (a mixed consortia of Bacillus strains ( Bacillus subtilis, Bacillus cereus, Bacillus firmus, Bacillus fusiformis, Bacillus macroides and Bacillus licheniformis), Pseudomonas spp., Shewanella spp. and a mixed consortia of Acidithiobcillus caldus, Leptospirillum spp., Ferroplasma spp. and Sulphobacillus spp.). The purpose of the study was to compare the removal efficiencies of the bacterial strains versus natural clinoptilolite adsorbents for metal cations. The Bacillus consortia removed most of the metals up to 98% metal removal efficiency with the exception of nickel where clinoptilolite showed good removal efficiency. The 0.02 M HCl-activated clinoptilolite also demonstrated excellent removal capabilities with Cu, Co and Fe removal efficiency of up to 98%. Both clinoptilolite and bacteria demonstrated capabilities of removing Cu 2+, Co 2+, Fe 2+, Mn 2+, As 3+ and Au from solution which augurs well for metal recovery from mining and mineral processing solutions, as well as in water decontamination.

  18. Carbonates-based noble metal-free lean NOx trap catalysts MOx-K2CO3/K2Ti8O17 (M = Ce, Fe, Cu, Co) with superior catalytic performance

    Science.gov (United States)

    Zhang, Yuxia; You, Rui; Liu, Dongsheng; Liu, Cheng; Li, Xingang; Tian, Ye; Jiang, Zheng; Zhang, Shuo; Huang, Yuying; Zha, Yuqing; Meng, Ming

    2015-12-01

    A series of base metal-based lean NOx trap (LNT) catalysts MOx-K2CO3/K2Ti8O17 (M = Ce, Fe, Cu, Co) were synthesized by successive impregnations and employed for the storage and reduction of NOx in the emissions of lean-burn engines at 350 °C. The XRD and XANES/EXAFS results reveal that the active phases in the corresponding catalysts exist as CeO2, Fe2O3, CuO and Co3O4, respectively. Among all the catalysts, CoOx-K2CO3/K2Ti8O17 exhibits the best performance, which cannot only trap the NOx quickly and completely at lean condition, giving the highest storage capacity (3.32 mmol/g) reported so far, but also reduce the NOx at rich condition, showing a NOx reduction percentage as high as 99.0%. Meanwhile, this catalyst displays an ultralow NOx to N2O selectivity (0.3%) during NOx reduction. The excellent performance of CoOx-K2CO3/K2Ti8O17 results from its largest amount of surface active oxygen species as revealed by XPS, O2-TPD and NO-TPD. HRTEM, FT-IR and CO2-TPD results illustrate that several kinds of K species such as sbnd OK groups, K2O, surface carbonates and bulk or bulk-like carbonates coexist in the catalysts. Based upon the in situ DRIFTS results, the participation of K2CO3 in NOx storage is confirmed, and the predominant NOx storage species is revealed as bidentate nitrites formed via multiple kinetic pathways. The low cost and high catalytic performance of the CoOx-based LNT catalyst make it most promising for the substitution of noble metal-based LNT catalysts.

  19. Environmental remediation through sequestration of airfall-derived metals contamination by selective revegetation strategies

    Science.gov (United States)

    Sahagian, D.; Peters, S.; Yasko, G.

    2006-12-01

    Industrial activities in the 20th century left a legacy of contaminated air, water, and soils. The relative environmental enlightenment of the 21st century has already led to reductions in pollution sources, and has improved air and surface water quality in many areas. However, the residence time of contaminants in soils can be lengthy, presenting a challenge to 21st century restoration of impacted ecosystems and communities. The present study is centered on the Borough of Palmerton, PA, and a broad region of adjacent communities that were affected by two zinc smelters that operated continuously for more than 80 years, emitting thousands of tons of heavy metals including zinc, cadmium, lead and arsenic. While the air quality has vastly improved since the closure of the zinc smelters, the community remains adversely affected by the ecological damage caused by the pollution. The north face of the Kittatiny ridge was completely denuded of vegetation from the high metals concentrations. The region suffers further due to the ongoing perception of contaminated soils and water, leaving the town and surrounding areas economically depressed. In this study, we are examining the impact of revegetation strategies, particularly those using warm season grasses to determine which species survive and indeed thrive in the metals-contaminated soils. Because of the large areal extent and locally steep slopes in the broad area of concern, removal of metals from the entire region is impractical. It is considered more effective to sequester the metals in the soil so that they do not leach into the rivers, or enter the food web. Vegetation that absorbs and transports the metals throughout its tissues would mobilize these pollutants into the food web as well as make the metals available to reach the river via leaves and other vegetative structures. In this study, we are monitoring the uptake of metals by test grasses and other plants that are colonizing the contaminated area, as well as

  20. Ion dynamics in laser ablation plumes from selected metals at 355 nm

    DEFF Research Database (Denmark)

    Thestrup Nielsen, Birgitte; Christensen, Bo Toftmann; Schou, Jørgen

    2002-01-01

    The dynamics of ions in a laser ablation plume from a number of metals irradiated by a ns-second pulse at 355 nm has been studied. The time-of-flight signals peak at flight times corresponding to velocities between 30 and 10 km/s with decreasing values for increasing atomic masses. The angular...... distributions of the integrated ion signals are strongly peaked in forward direction, and the values for the volatile Bi are somewhat higher than those for the other metals. The distributions have been analyzed on the basis of Anisimov's expansion model. The fraction of ionized atoms can be estimated from...

  1. Selective epitaxial growth of Ge1-xSnx on Si by using metal-organic chemical vapor deposition

    Science.gov (United States)

    Washizu, Tomoya; Ike, Shinichi; Inuzuka, Yuki; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

    2017-06-01

    Selective epitaxial growth of Ge and Ge1-xSnx layers on Si substrates was performed by using metal-organic chemical vapor deposition (MOCVD) with precursors of tertiary-butyl-germane (t-BGe) and tri-butyl-vinyl-tin (TBVSn). We investigated the effects of growth temperature and total pressure during growth on the selectivity and the crystallinity of the Ge and Ge1-xSnx epitaxial layers. Under low total pressure growth conditions, the dominant mechanism of the selective growth of Ge epitaxial layers is the desorption of the Ge precursors. At a high total pressure case, it is needed to control the surface migration of precursors to realize the selectivity because the desorption of Ge precursors was suppressed. The selectivity of Ge growth was improved by diffusion of the Ge precursors on the SiO2 surfaces when patterned substrates were used at a high total pressure. The selective epitaxial growth of Ge1-xSnx layer was also realized using MOCVD. We found that the Sn precursors less likely to desorb from the SiO2 surfaces than the Ge precursors.

  2. Contabilidad Financiera Superior

    OpenAIRE

    Ipiñazar Petralanda, Izaskun

    2013-01-01

    Duración (en horas): De 31 a 40 horas. Destinatario: Estudiante y Docente A través de este material se presentan las pautas necesarias para implementar un aprendizaje basado en problemas en la asignatura de Contabilidad Financiera Superior dentro de los temas “Constitución de S.A. y S.R.L.” (Tema 2), “Ampliaciones de Capital” (Tema 3) y “Reducciones de Capital” (Tema 4). En primer lugar se presentan las guías generales de la asignatura, y a continuación, las diferentes activida...

  3. Contabilidad Financiera Superior

    OpenAIRE

    Ipiñazar Petralanda, Izaskun

    2013-01-01

    Duración (en horas): De 31 a 40 horas. Destinatario: Estudiante y Docente A través de este material se presentan las pautas necesarias para implementar un aprendizaje basado en problemas en la asignatura de Contabilidad Financiera Superior dentro de los temas “Constitución de S.A. y S.R.L.” (Tema 2), “Ampliaciones de Capital” (Tema 3) y “Reducciones de Capital” (Tema 4). En primer lugar se presentan las guías generales de la asignatura, y a continuación, las diferentes activida...

  4. Trends in the Hydrodeoxygenation Activity and Selectivity of Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Lausche, Adam C.; Falsig, Hanne; Jensen, Anker Degn

    2014-01-01

    This paper reports the use of a combination of density functional theory and microkinetic modelling to establish trends in the hydrodeoxygenation rates and selectivites of transition metal surfaces. Biomass and biomass-derived chemicals often contain large fractions of oxygenates. Removal of the ...

  5. Heavy Metals in selected Edible Vegetables and their daily intake in Sanandaj, Iran

    Energy Technology Data Exchange (ETDEWEB)

    Alasvand Zarasvand, M.; Maleki, A.

    2009-07-01

    The levels of four different heavy metals [cadmium (Cd), lead (Pb), chromium (Cr) and copper (Cu)] were determined in various vegetables [leek (Allium ampeloprasum), sweet basil (Ocimum basilicum), parsley (Petroselium cripsum), gardem cress (lepidium sativum) and tarragon (Artemisia dracuncullus)] cultivated around the Sanandaj city. (Author)

  6. Highly Selective Water Adsorption in a Lanthanum Metal-Organic Framework

    NARCIS (Netherlands)

    Plessius, R.; Kromhout, R.; Dantas Ramos, A.L.; Ferbinteanu, M.; Mittelmeijer-Hazeleger, M.C.; Krishna, R.; Rothenberg, G.; Tanase, S.

    2014-01-01

    We present a new metal-organic framework (MOF) built from lanthanum and pyrazine-2,5-dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)(1.5)(H2O)(2)]center dot 2H(2)O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration

  7. Innovative developments in the selective removal and reuse of heavy metals from wastewaters

    NARCIS (Netherlands)

    Veeken, A.H.M.; Rulkens, W.H.

    2003-01-01

    Sulphide precipitation of heavy metal containing wastewaters results in low effluent concentrations. However, sulphide precipitation is not widely applied in practice because the dosing of sulphide cannot adequately be controlled. A new process was developed where the combination of a sulphide-selec

  8. Concentration of selected heavy metals in water of the Juru River ...

    African Journals Online (AJOL)

    HP

    2012-04-24

    Apr 24, 2012 ... lowest concentrations of some heavy metals were in estuary zone, it seems to be naturally due to dilution to heavy ... plankton, benthos or fish and finally transferred to humans (Ahmad ... Sampling was undertaken two times along the Juru River which involves 20 .... Results show that the concentrations of.

  9. A highly efficient and selective polysilsesquioxane sorbent for heavy metal removal

    KAUST Repository

    Duan, Xiaonan

    2012-02-29

    Suited for heavy stuff: An efficient mesoporous sorbent based on a pure ethylendiamine-bridged polysilsesquioxane is presented. This material, with both a high amine loading and a high surface area, is applied for heavy metal ion removal. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Metal/oxide interfacial effects on the selective oxidation of primary alcohols

    Science.gov (United States)

    Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

    2017-01-01

    A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O-H and C-H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged.

  11. Heavy metals in selected edible vegetables and estimation of their daily intake in Sanandaj, Iran.

    Science.gov (United States)

    Maleki, Afshin; Zarasvand, Masoud Alasvand

    2008-03-01

    The levels of four different heavy metals [cadmium (Cd), lead (Pb), chromium (Cr) and copper (Cu)] were determined in various vegetables [leek (Allium ampeloprasum), sweet basil (Ocimum basilicum), parsley (Petroselinum crispum), garden cress (Lepidium sativum) and tarragon (Artemisia dracunculus)] cultivated around Sanandaj City. The contributions of the vegetables to the daily intake of heavy metals from vegetables were investigated. One hundred samples (20 samples per month) were collected for five months. Atomic absorption spectrometry was used to determine the concentrations of these metals in the vegetables. The average concentrations of each heavy metal regardless of the kind of vegetable for Pb, Cu, Cr and Cd were 13.60 +/- 2.27, 11.50 +/- 2.16, 7.90 +/- 1.05 and 0.31 +/- 0.17 mg/kg, respectively. Based on the above concentrations and the information of National Nutrition and Food Research Institute of Iran, the dietary intake of Pb, Cu, Cr and Cd through vegetable consumption was estimated at 2.96, 2.50, 1.72 and 0.07 mg/day, respectively. It is concluded that the vegetables grown in this region are a health hazard for human consumption.

  12. Levels of selected metals in canned fish consumed in Kingdom of Saudi Arabia.

    Science.gov (United States)

    Ashraf, Waqar; Seddigi, Zaki; Abulkibash, Abdallah; Khalid, Mazen

    2006-06-01

    In the present paper, seven heavy metals (Pb, Cd, Ni, Cu, Zn, Cr and Fe) in canned salmon, sardine and tuna fish were determined by using atomic absorption spectroscopy. Cadmium and lead levels were determined by graphite tube AAS whereas Ni, Cu, Cr and Fe were determined by flame AAS. Analytical results were validated by spiking the samples with various concentrations of these metals for recovery. The metal contents, expressed in microg/g, wet weight, varied depending upon the specie studied. The levels of Pb ranged from 0.03-1.20 microg-g(-1) with an average of 0.313 microg-g(-1) for salmon; 0.03-0.51 microg-g(-1) with an average of 0.233 microg-g(-1) for tuna and 0.13-1.97 microg-g(-1) with an average of 0.835 microg-g(-1) for sardines. The levels of Cd ranged from 0.02-0.38 microg-g(-1) with an average of 0.161 microg-g(-1) for salmon; 0.07-0.64 microg-g(-1) with an average of 0.227 microg-g(-1) for tuna and 0.010-0.690 microg-g(-1) with an average of 0.183 microg-g(-1) for sardines. Comparative evaluation of these metals in three varieties of fish showed that average concentration of lead in sardines is about 4 times and Ni about 3 times higher as compared to tuna. Generally, the levels of these metals follow the order sardine > salmon > tuna. The data generated in the present study compared well with the similar studies carried out in different parts of the world. The results indicate that canned fish, in general and tuna in particular, have concentrations within permissible limits of WHO/FAO levels for these heavy metals. Therefore, their contribution to the total body burden of these metals can be considered as negligibly small.

  13. Research on Selective Shredding of Wasted Printed Circuit Boards

    Institute of Scientific and Technical Information of China (English)

    曹亦俊; 文学峰; 赵跃民

    2002-01-01

    Electronic scrap, especially wasted printed circuit boards (PCBs), is regarded as an environmental challenge. At present, the physical separation is thought to be the environmental friendly and economical method of treating and reutilizing electronic waste. An effective liberation of metals from non-metallic components is a crucial step towards mechanical separation and recycling of wasted PCBs. In this paper, the selective shredding theory and mechanics characteristics of wasted PCBs were analyzed, and the shredded experiments of wasted PCBs by hammer mill were investigated. The result shows that the selective shredding exists in the wasted PCBs shredded process by hammer mill. The shredding velocity of non-metallic components is far greater than that of metals in the wasted PCBs shredding, which makes the metals concentrate in the coarser fraction. And the impact force of hammer mill is superior to metal liberation from non-metallic components, a satisfied metal liberation degree can be achieved in the wasted PCBs shredding by hammer mill.

  14. Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-12-22

    Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

  15. Selective extraction and detection of noble metal based on ionic liquid immobilized silica gel surface using ICP-OES

    Indian Academy of Sciences (India)

    HADI M MARWANI; AMJAD E ALSAFRANI; HAMAD A AL-TURAIF; ABDULLAH M ASIRI; SHER BAHADAR KHAN

    2016-08-01

    In this study, an efficiently employed ionic liquid combined with commercially available silica gel (SG–ClPrNTf$_2$) was developed for selective detection of gold(III) by use of inductively coupled plasma–optical emission spectrometry (ICP-OES). The selectivity of SG–ClPrNTf$_2$ was evaluated towards seven metal ions, including Y(III), Mn(II), Zr(IV), Pb(II), Mg(II), Pd(II) and Au(III). Based on pH study and distribution coefficient values, the SG–ClPrNTf$_2$ phase was found to be the most selective towards Au(III) at pH 2 as compared to other metal ions. The adsorption isotherm of Au(III) on the SG–ClPrNTf$_2$ phase followed the Langmuir model with adsorption capacity of 59.48 mg g$^{−1}$, which was highly in agreement with experimental data of adsorption isotherm study. The kinetics study indicated that Au(III) adsorption kinetics data were well fit with the pseudo-second-order kinetic model on the basis of correlation coefficient fitting (0.996) and adsorption capacity agreement (62.26 mg g$^{−1}$). Furthermore, SG–ClPrNTf$_2$ phase was effectively performed for the determination of Au(III) in real water samples with satisfactory results.

  16. Metal artifact correction for x-ray computed tomography using kV and selective MV imaging

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Meng, E-mail: mengwu@stanford.edu [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Keil, Andreas [microDimensions GmbH, Munich 81379 (Germany); Constantin, Dragos; Star-Lack, Josh [Varian Medical Systems, Inc., Palo Alto, California 94304 (United States); Zhu, Lei [Nuclear and Radiological Engineering and Medical Physics Programs, The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

    2014-12-15

    Purpose: The overall goal of this work is to improve the computed tomography (CT) image quality for patients with metal implants or fillings by completing the missing kilovoltage (kV) projection data with selectively acquired megavoltage (MV) data that do not suffer from photon starvation. When both of these imaging systems, which are available on current radiotherapy devices, are used, metal streak artifacts are avoided, and the soft-tissue contrast is restored, even for regions in which the kV data cannot contribute any information. Methods: Three image-reconstruction methods, including two filtered back-projection (FBP)-based analytic methods and one iterative method, for combining kV and MV projection data from the two on-board imaging systems of a radiotherapy device are presented in this work. The analytic reconstruction methods modify the MV data based on the information in the projection or image domains and then patch the data onto the kV projections for a FBP reconstruction. In the iterative reconstruction, the authors used dual-energy (DE) penalized weighted least-squares (PWLS) methods to simultaneously combine the kV/MV data and perform the reconstruction. Results: The authors compared kV/MV reconstructions to kV-only reconstructions using a dental phantom with fillings and a hip-implant numerical phantom. Simulation results indicated that dual-energy sinogram patch FBP and the modified dual-energy PWLS method can successfully suppress metal streak artifacts and restore information lost due to photon starvation in the kV projections. The root-mean-square errors of soft-tissue patterns obtained using combined kV/MV data are 10–15 Hounsfield units smaller than those of the kV-only images, and the structural similarity index measure also indicates a 5%–10% improvement in the image quality. The added dose from the MV scan is much less than the dose from the kV scan if a high efficiency MV detector is assumed. Conclusions: The authors have shown that it

  17. Oral bioavailability of arsenic, antimony and a selection of metals in ashes; Oral biotillgaenglighet av arsenik, antimon och ett urval av metaller i askor

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Christel; Bendz, David; Jones, Celia

    2008-06-15

    In an earlier study, financed by Varmeforsk, 'Q4-238 Environmental guidelines for reuse of ash in civil engineering applications', the total content of arsenic and lead was shown to determine whether or not reuse of some of the ashes in construction work is feasible. The model used to calculate the guidelines uses the total concentration of metals to evaluate the health risks resulting from exposure to the ashes. The use of total concentration can lead to overly conservative risk assessments if a significant fraction of the total metal content is not bioavailable. Better precision in the risk assessment can be given by the use of the bioavailable fraction of arsenic and lead in the model. As a result, ashes which are rejected on the basis of total metal concentration may be acceptable for use in engineering construction when the assessment is based on the bioavailable fraction. The purpose of the study was to (i) compile information on the oral bioavailability of arsenic, antimony and a selection of metals in ashes and similar materials, and on in vitro methods for determination of oral bioavailability, and (ii) experimentally estimate oral bioavailability of arsenic, antimony and some metals in a selection of ashes by analysis of the gastrointestinal bioaccessibility of these elements. The investigated elements were antimony, arsenic, lead, cadmium, copper, chromium, nickel and zinc. In the literature study performed within the project a number of static and dynamic in vitro methods simulating gastrointestinal processes of contaminants were compiled. The methods include one or several segments, i.e. mouth, stomach and intestine. Among the compiled methods, the RIVM (Rijksinstituut voor volksgesundheid en milieu) in vitro method was used in the experimental part of the project. The advantages with the method was that: the method to a high degree mimicked the human gastrointestinal processes (the method included three segments mouth, stomach, and intestine

  18. Statistics of superior records

    Science.gov (United States)

    Ben-Naim, E.; Krapivsky, P. L.

    2013-08-01

    We study statistics of records in a sequence of random variables. These identical and independently distributed variables are drawn from the parent distribution ρ. The running record equals the maximum of all elements in the sequence up to a given point. We define a superior sequence as one where all running records are above the average record expected for the parent distribution ρ. We find that the fraction of superior sequences SN decays algebraically with sequence length N, SN˜N-β in the limit N→∞. Interestingly, the decay exponent β is nontrivial, being the root of an integral equation. For example, when ρ is a uniform distribution with compact support, we find β=0.450265. In general, the tail of the parent distribution governs the exponent β. We also consider the dual problem of inferior sequences, where all records are below average, and find that the fraction of inferior sequences IN decays algebraically, albeit with a different decay exponent, IN˜N-α. We use the above statistical measures to analyze earthquake data.

  19. Frenillo labial superior doble

    Directory of Open Access Journals (Sweden)

    Carlos Albornoz López del Castillo

    Full Text Available El frenillo labial superior doble no sindrómico es una anomalía del desarrollo que no hemos encontrado reportada en la revisión bibliográfica realizada. Se presenta una niña de 11 años de edad que fue remitida al servicio de Cirugía Maxilofacial del Hospital "Eduardo Agramonte Piña", de Camagüey, por presentar un frenillo labial superior doble de baja inserción. Se describen los síntomas clínicos asociados a esta anomalía y el tratamiento quirúrgico utilizado para su solución: una frenectomía y plastia sobre la banda muscular frénica anormal que provocaba exceso de tejido en la mucosa labial. Consideramos muy interesante la descripción de este caso, por no haber encontrado reporte similar en la literatura revisada.

  20. Activity and Selectivity for O-2 Reduction to H2O2 on Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Verdaguer Casadevall, Arnau; Karamad, Mohammadreza;

    2013-01-01

    Industrially viable electrochemical production of H2O2 requires active, selective and stable electrocatalyst materials to catalyse the oxygen reduction reaction to H2O2. On the basis of density functional theory calculations, we explain why single site catalysts such as Pd/Au show improved select...

  1. An efficient noble-metal-free supported copper catalyst for selective nitrocyclohexane hydrogenation to cyclohexanone oxime.

    Science.gov (United States)

    Zhang, Qian-Qian; Dong, Jing; Liu, Yong-Mei; Cao, Yong; He, He-Yong; Wang, Yang-Dong

    2017-03-07

    It was shown for the first time that cyclohexanone oxime (CHO) can be selectively produced by heterogeneous copper-catalyzed hydrogenative transformation of nitrocyclohexane (NC). The combination of Cu(0) and Cu(+) and their cooperative interaction with weakly acidic SiO2 supports elicited a significantly unique and selective catalysis in the hydrogenation of NC to CHO.

  2. Towards bond selective chemistry from first principles: methane on metal surfaces.

    Science.gov (United States)

    Shen, X J; Lozano, A; Dong, W; Busnengo, H F; Yan, X H

    2014-01-31

    Controlling bond-selective chemical reactivity is of great importance and has a broad range of applications. Here, we present a molecular dynamics study of bond selective reactivity of methane and its deuterated isotopologues (i.e., CH(4-x)D(x), x=0,1,2,3,4) on Ni(111) and Pt(111) from first principles calculations. Our simulations allow for reproducing the full C-H bond selectivity recently achieved experimentally via mode-specific vibrational excitation and explain its origin. Moreover, we also predict the hitherto unexplored influence of the molecular translational energy on such a selectivity as well as the conditions under which the full selectivity can be realized for the a priori less active C-D bond.

  3. Molybdenum carbide as alternative catalysts to precious metals for highly selective reduction of CO2 to CO.

    Science.gov (United States)

    Porosoff, Marc D; Yang, Xiaofang; Boscoboinik, J Anibal; Chen, Jingguang G

    2014-06-23

    Rising atmospheric CO2 is expected to have negative effects on the global environment from its role in climate change and ocean acidification. Utilizing CO2 as a feedstock to make valuable chemicals is potentially more desirable than sequestration. A substantial reduction of CO2 levels requires a large-scale CO2 catalytic conversion process, which in turn requires the discovery of low-cost catalysts. Results from the current study demonstrate the feasibility of using the non-precious metal material molybdenum carbide (Mo2C) as an active and selective catalyst for CO2 conversion by H2.

  4. Polyamide-scorpion cyclam lexitropsins selectively bind AT-rich DNA independently of the nature of the coordinated metal.

    Directory of Open Access Journals (Sweden)

    Anthony T S Lo

    Full Text Available Cyclam was attached to 1-, 2- and 3-pyrrole lexitropsins for the first time through a synthetically facile copper-catalyzed "click" reaction. The corresponding copper and zinc complexes were synthesized and characterized. The ligand and its complexes bound AT-rich DNA selectively over GC-rich DNA, and the thermodynamic profile of the binding was evaluated by isothermal titration calorimetry. The metal, encapsulated in a scorpion azamacrocyclic complex, did not affect the binding, which was dominated by the organic tail.

  5. 抗松材线虫赤松组培繁殖优良家系的筛选%Selection of wilt-resistant Pinus densiflora superior families for tissue culture propagation

    Institute of Scientific and Technical Information of China (English)

    李清清; 叶建仁; 吴小芹

    2013-01-01

    Using the embryo seedlings with cotyledons of 27 wilt-resistant Pinus densiflora families as explants, superior families which were good growth vigor, high multiplication rate and strong rooting ability were selected. The average e-longation percentages of No. 1, 8, 10, 13, 22 and 25 families were up to above 100% ; With the increase of proliferation generations, the multiplication coefficient of clustered shoots in each family was variable, but the overall trend was that multiplication coefficient of clustered shoots from generation 1 to generation 2 increased with generation increase, and multiplication coefficient from generation 2 to generation 3 decreased; Adventitious root induction rate of wilt-resistant P. densiflora clones was different, 19-B clone of wilt-resistant P. densiflora was the highest,up to 95. 8% .%以抗松材线虫赤松(简称抗病赤松)27个家系带子叶顶芽的胚苗为外植体,筛选生长势好、增殖系数高和生根能力强的组培繁殖优良家系.结果表明:1、8、10、13、22和25家系的平均伸长率都达到了100%以上;随着增殖代数的增加,各家系丛生芽增殖系数表现不一致,但总体趋势是l至2代丛生芽增殖系数随代数增加而增加,2至3代增殖系数随代数增加而下降;抗病赤松不同无性系不定根诱导率不同,19-B无性系的不定根诱导率最高为95.8%.

  6. Activation of the metal-organic framework MIL-47 for selective adsorption of xylenes and other difunctionalized aromatics.

    Science.gov (United States)

    Alaerts, Luc; Maes, Michael; Jacobs, Pierre A; Denayer, Joeri F M; De Vos, Dirk E

    2008-05-28

    The capacity and selectivity of the metal-organic framework MIL-47 for liquid phase adsorption are shown to heavily depend on the pretreatment of the material, as illustrated in detail by the particular case of selective xylene adsorption. By totally removing the uncoordinated terephthalic acid from the pores and simultaneously avoiding oxidation to nonporous V(2)O(5), pore volume and uptake of xylenes can be maximized. The presence of uncoordinated terephthalic acid in the pores improves the selectivity between p- and m-xylene. Calcination bed thickness and oven geometry influence the optimal calcination procedure. The physicochemical modifications of MIL-47 during its activation are investigated in detail with XRD, SEM, nitrogen physisorption, TGA and diffuse reflectance UV-Vis spectroscopy. Using optimally pretreated MIL-47 as adsorbent for xylene, ethyltoluene, dichlorobenzene, toluidine or cresol isomers, the para-isomer is in each case preferred over the meta-isomer in pulse chromatographic and batch experiments. The role of stacking in the selective adsorption of these isomers is discussed. In the case of the dichlorobenzenes, the meta- and para-isomers can be separated in a breakthrough experiment with a selectivity of 5.0.

  7. Co-Selection of Resistance to Antibiotics, Biocides and Heavy Metals, and Its Relevance to Foodborne Pathogens

    Directory of Open Access Journals (Sweden)

    Andrew D. Wales

    2015-11-01

    Full Text Available Concerns have been raised in recent years regarding co-selection for antibiotic resistance among bacteria exposed to biocides used as disinfectants, antiseptics and preservatives, and to heavy metals (particularly copper and zinc used as growth promoters and therapeutic agents for some livestock species. There is indeed experimental and observational evidence that exposure to these non-antibiotic antimicrobial agents can induce or select for bacterial adaptations that result in decreased susceptibility to one or more antibiotics. This may occur via cellular mechanisms that are protective across multiple classes of antimicrobial agents or by selection of genetic determinants for resistance to non-antibiotic agents that are linked to genes for antibiotic resistance. There may also be relevant effects of these antimicrobial agents on bacterial community structure and via non-specific mechanisms such as mobilization of genetic elements or mutagenesis. Notably, some co-selective adaptations have adverse effects on fitness in the absence of a continued selective pressure. The present review examines the evidence for the significance of these phenomena, particularly in respect of bacterial zoonotic agents that commonly occur in livestock and that may be transmitted, directly or via the food chain, to human populations.

  8. Geochemical modelling and speciation studies of metal pollutants present in selected water systems in South Africa

    Science.gov (United States)

    Magu, M. M.; Govender, P. P.; Ngila, J. C.

    2016-04-01

    Metal pollutants in water poses great threats to living beings and hence requires to be monitored regularly to avoid loss of lives. Various analytical methods are available to monitor these pollutants in water and can be improved with time. Modelling of metal pollutants in any water system helps chemists, engineers and environmentalists to greatly understand the various chemical processes in such systems. Water samples were collected from waste water treatment plant and river from highlands close to its source all the way to the ocean as it passing through areas with high anthropogenic activities. Pre-concentration of pollutants in the samples was done through acid digestion and metal pollutants were analysed using inductively coupled plasma-optical emission spectra (ICP-OES) to determine the concentration levels. Metal concentrations ranged between 0.1356-0.4658 mg/L for Al; 0.0031-0.0050 mg/L for Co, 0.0019-0.0956 mg/L for Cr; 0.0028-0.3484 mg/L for Cu; 0.0489-0.3474 mg/L for Fe; 0.0033-0.0285 mg/L for Mn; 0.0056-0.0222 mg/L for Ni; 0.0265-0.4753 mg/L for Pb and 0.0052-0.5594 mg/L for Zn. Modelling work was performed using PHREEQC couple with Geochemist's workbench (GWB) to determine speciation dynamics and bioavailability of these pollutants. Modelling thus adds value to analytical methods and hence a better complementary tool to laboratory-based experimental studies.

  9. Metal complex with terpyrindine derivative ligand as highly selective colorimetric sensor for iron(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Taka-aki Okamura; Hong-Ping Zhou; Wei-Yin Sun; Yu-Peng Tian

    2013-01-01

    A new metal complex [MnL2](NO3)2.CH3CN (1) was synthesized by reaction of 4'-4-(1,2,4-triazol-1-yl)-phenyl-2,2':6',2"-terpyridine (L) with manganese nitrate.The structure of the complex was determined by X-ray crystallography.The results of UV-vis studies showed that the complex exhibits colorimetric sensing ability for Fe3+,which can be observed by naked eye.

  10. Extraction procedure testing of solid wastes generated at selected metal ore mines and mills

    Science.gov (United States)

    Harty, David M.; Terlecky, P. Michael

    1986-09-01

    Solid waste samples from a reconnaissance study conducted at ore mining and milling sites were subjected to the U.S. Environmental Protection Agency extraction procedure (EP) leaching test Sites visited included mines and mills extracting ores of antimony (Sb), mercury (Hg), vanadium (V), tungsten (W), and nickel (Ni). Samples analyzed included mine wastes, treatment pond solids, tailings, low grade ore, and other solid wastes generated at these facilities Analysis of the leachate from these tests indicates that none of the samples generated leachate in which the concentration of any toxic metal parameter exceeded EPA criteria levels for those metals. By volume, tailings generally constitute the largest amount of solid wastes generated, but these data indicate that with proper management and monitoring, current EPA criteria can be met for tailings and for most solid wastes associated with mining and milling of these metal ores. Long-term studies are needed to determine if leachate characteristics change with time and to assist in development of closure plans and post closure monitoring programs.

  11. Highly sensitive and selective fluoride detection in water through fluorophore release from a metal-organic framework.

    Science.gov (United States)

    Hinterholzinger, Florian M; Rühle, Bastian; Wuttke, Stefan; Karaghiosoff, Konstantin; Bein, Thomas

    2013-01-01

    The detection, differentiation and visualization of compounds such as gases, liquids or ions are key challenges for the design of selective optical chemosensors. Optical chemical sensors employ a transduction mechanism that converts a specific analyte recognition event into an optical signal. Here we report a novel concept for fluoride ion sensing where a porous crystalline framework serves as a host for a fluorescent reporter molecule. The detection is based on the decomposition of the host scaffold which induces the release of the fluorescent dye molecule. Specifically, the hybrid composite of the metal-organic framework NH2-MIL-101(Al) and fluorescein acting as reporter shows an exceptional turn-on fluorescence in aqueous fluoride-containing solutions. Using this novel strategy, the optical detection of fluoride is extremely sensitive and highly selective in the presence of many other anions.

  12. Characterization of toxic metals in tobacco, tobacco smoke, and cigarette ash from selected imported and local brands in Pakistan.

    Science.gov (United States)

    Ajab, Huma; Yaqub, Asim; Malik, Salman Akbar; Junaid, Muhammad; Yasmeen, Sadia; Abdullah, Mohd Azmuddin

    2014-01-01

    In this study, concentrations of Cd, Ni, Pb, and Cr were determined in tobacco, tobacco smoke-condensate, and cigarette ash for selected brands used in Pakistan. Smoking apparatus was designed for metal extraction from cigarette smoke. Samples were digested through microwave digester and then analyzed by flame atomic absorption spectrophotometer (FAAS). Higher concentration of Ni was detected in imported brands than the counterparts in the local brands. Pb levels were however higher in local brands while significant concentration of Cd was observed in both brands. For Cr, the level in tobacco of local brands was higher than their emitted smoke, whereas imported brands showed higher level in smoke than in tobacco. The cigarette ash retained 65 to 75% of the metal and about 25 to 30% went into the body. While this study revealed the serious requirement to standardize the manufacturing of tobacco products, more importantly is the urgent need for stronger enforcements to put in place to alert the general population about the hazardous effects of cigarettes and the health risks associated with these toxic metals.

  13. Ion-selective electrodes with solid contact for heavy metals determination

    OpenAIRE

    2013-01-01

    Potentiometric properties of ion-selective electrodes with solid contact for lead, cadmium and zinc determination were investigated. The ionic liquids (ILs) alkyl methyl imidazolium chlorides are used as lipophilic ionic additive to the membrane phase and as transducer media. The basic analytical parameters of the studied electrodes, such as the slope characteristic, the detection limit, response time, lifetime, selectivity coefficients against various inorganic cations as well as the depende...

  14. Photocatalytic Metal-Organic Frameworks for Selective 2,2,2-Trifluoroethylation of Styrenes.

    Science.gov (United States)

    Yu, Xiao; Cohen, Seth M

    2016-09-28

    Synthesis of CF3-containing compounds is of great interest because of their broad use in the pharmaceutical and agrochemical industries. Herein, selective 2,2,2-trifluoroethylation of styrenes was catalyzed by Zr(IV)-based MOFs bearing visible-light photocatalysts in the form of Ir(III) polypyridyl complexes. When compared to the homogeneous Ir(III) catalyst, the MOF-based catalyst suppressed the dimerization of benzyl radicals, thus enhancing the selectivity of the desired hydroxytrifluoroethyl compounds.

  15. Transition Metal Phosphide Nanoparticles Supported on SBA-15 as Highly Selective Hydrodeoxygenation Catalysts for the Production of Advanced Biofuels.

    Science.gov (United States)

    Yang, Yongxing; Ochoa-Hernández, Cristina; de la Peña O'Shea, Víctor A; Pizarro, Patricia; Coronado, Juan M; Serrano, David P

    2015-09-01

    A series of catalysts constituted by nanoparticles of transition metal (M = Fe, Co, Ni and Mo) phosphides (TMP) dispersed on SBA-15 were synthesized by reduction of the corresponding metal phosphate precursors previously impregnated on the mesostructured support. All the samples contained a metal-loading of 20 wt% and with an initial M/P mole ratio of 1, and they were characterized by X-ray diffraction (XRD), N2 sorption, H2-TPR and transmission electron microscopy (TEM). Metal phosphide nanocatalysts were tested in a high pressure continuous flow reactor for the hydrodeoxygenation (HDO) of a methyl ester blend containing methyl oleate (C17H33-COO-CH3) as main component (70%). This mixture constitutes a convenient surrogate of triglycerides present in vegetable oils, and following catalytic hydrotreating yields mainly n-alkanes. The results of the catalytic assays indicate that Ni2P/SBA-15 catalyst presents the highest ester conversion, whereas the transformation rate is about 20% lower for MoP/SBA-15. In contrast, catalysts based on Fe and Co phosphides show a rather limited activity. Hydrocarbon distribution in the liquid product suggests that both hydrodeoxygenation and decarboxylation/decarbonylation reactions occur simultaneously over the different catalysts, although MoP/SBA-15 possess a selectivity towards hydrodeoxygenation exceeding 90%. Accordingly, the catalyst based on MoP affords the highest yield of n-octadecane, which is the preferred product in terms of carbon atom economy. Subsequently, in order to conjugate the advantages of both Ni and Mo phosphides, a series of catalysts containing variable proportions of both metals were prepared. The obtained results reveal that the mixed phosphides catalysts present a catalytic behavior intermediate between those of the monometallic phosphides. Accordingly, only marginal enhancement of the yield of n-octadecane is obtained for the catalysts with a Mo/Ni ratio of 3. Nevertheless, owing to this high selectivity

  16. Selective deposition of Pt onto supported metal clusters for fuel cell electrocatalysts

    Science.gov (United States)

    Jeon, Tae-Yeol; Pinna, Nicola; Yoo, Sung Jong; Ahn, Docheon; Choi, Sun Hee; Willinger, Marc-Georg; Cho, Yong-Hun; Lee, Kug-Seung; Park, Hee-Young; Yu, Seung-Ho; Sung, Yung-Eun

    2012-09-01

    We report a new method for deposition of Pt on a metal core to develop real electrocatalysts with significantly reduced amounts of expensive Pt as well as enhanced activity for oxygen reduction reaction. Ru and Pd have different crystal structures and modify the electronic structure of Pt to a different extent (shifts in d-band center). They were chosen as core materials to examine whether hydroquinone dissolved in ethanol can be used to deposit additional Pt atoms onto preformed core nanoparticles, and whether the modified d-character of Pt on different host metals can result in the enhanced ORR activity. The physicochemical characteristics of Pd-Pt and Ru-Pt core-shell nanoparticles are investigated. The core-shell structure was identified through a combination of experimental methods, employing electron microscopy, electrochemical measurements, and synchrotron X-ray measurements such as powder X-ray diffraction, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. The hydroquinone reduction method proved to be an excellent route for the epitaxial growth of a Pt shell on the metal cores, leading to enhanced ORR activities.We report a new method for deposition of Pt on a metal core to develop real electrocatalysts with significantly reduced amounts of expensive Pt as well as enhanced activity for oxygen reduction reaction. Ru and Pd have different crystal structures and modify the electronic structure of Pt to a different extent (shifts in d-band center). They were chosen as core materials to examine whether hydroquinone dissolved in ethanol can be used to deposit additional Pt atoms onto preformed core nanoparticles, and whether the modified d-character of Pt on different host metals can result in the enhanced ORR activity. The physicochemical characteristics of Pd-Pt and Ru-Pt core-shell nanoparticles are investigated. The core-shell structure was identified through a combination of experimental methods, employing electron microscopy

  17. Design, selection, and characterization of thioflavin-based intercalation compounds with metal chelating properties for application in Alzheimer's disease.

    Science.gov (United States)

    Rodríguez-Rodríguez, Cristina; Sánchez de Groot, Natalia; Rimola, Albert; Alvarez-Larena, Angel; Lloveras, Vega; Vidal-Gancedo, José; Ventura, Salvador; Vendrell, Josep; Sodupe, Mariona; González-Duarte, Pilar

    2009-02-01

    Metal chelation is considered a rational therapeutic approach for interdicting Alzheimer's amyloid pathogenesis. At present, enhancing the targeting and efficacy of metal-ion chelating agents through ligand design is a main strategy in the development of the next generation of metal chelators. Inspired by the traditional dye Thioflavin-T, we have designed new multifunctional molecules that contain both amyloid binding and metal chelating properties. In silico techniques have enabled us to identify commercial compounds that enclose the designed molecular framework (M1), include potential antioxidant properties, facilitate the formation of iodine-labeled derivatives, and can be permeable through the blood-brain barrier. Iodination reactions of the selected compounds, 2-(2-hydroxyphenyl)benzoxazole (HBX), 2-(2-hydroxyphenyl)benzothiazole (HBT), and 2-(2-aminophenyl)-1H-benzimidazole (BM), have led to the corresponding iodinated derivatives HBXI, HBTI, and BMI, which have been characterized by X-ray diffraction. The chelating properties of the latter compounds toward Cu(II) and Zn(II) have been examined in the solid phase and in solution. The acidity constants of HBXI, HBTI, and BMI and the formation constants of the corresponding ML and ML2 complexes [M = Cu(II), Zn(II)] have been determined by UV-vis pH titrations. The calculated values for the overall formation constants for the ML2 complexes indicate the suitability of the HBXI, HBTI, and BMI ligands for sequestering Cu(II) and Zn(II) metal ions present in freshly prepared solutions of beta-amyloid (Abeta) peptide. This was confirmed by Abeta aggregation studies showing that these compounds are able to arrest the metal-promoted increase in amyloid fibril buildup. The fluorescence features of HBX, HBT, BM, and the corresponding iodinated derivatives, together with fluorescence microscopy studies on two types of pregrown fibrils, have shown that HBX and HBT compounds could behave as potential markers for the presence

  18. Selective synthesis of indazoles and indoles via triazene-alkyne cyclization switched by different metals.

    Science.gov (United States)

    Fang, Yan; Wang, Chengming; Su, Shengqin; Yu, Haizhu; Huang, Yong

    2014-02-21

    We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a triazene functionality underwent two distinct cyclization pathways mediated by different transition metals. Starting from the same substrates, a synthesis of 2H-indazole was accomplished by a Cu(II) salt promoted oxidative cyclization, while 2-substituted indoles could be accessed via a Ag(I) salt mediated N-N bond cleavage. This method represents the first synthesis of indoles from alkynyl triazenes. Computational analysis was performed for both reaction pathways, supporting a Lewis acid role for Cu and a π-acid catalysis for Ag.

  19. POLYMER COMPOSITE FILMS WITH SIZE-SELECTED METAL NANOPARTICLES FABRICATED BY CLUSTER BEAM TECHNIQUE

    DEFF Research Database (Denmark)

    Ceynowa, F. A.; Chirumamilla, Manohar; Popok, Vladimir

    2017-01-01

    after the deposition. The degree of immersion can be controlled by the annealing temperature and time. Together with control of cluster coverage the described approach represents an efficient method for the synthesis of thin polymer composite layers with either partially or fully embedded metal NPs......, in particular, for the use of phenomenon of localized surface plasmon resonance (LSPR). Unfortunately, it is found that the thermal annealing used in the production process can lead to quenching of plasmonic properties in the case of copper. To solve this problem, it is suggested to treat the samples with ozone...

  20. The arbuscular mycorrhizal status of poplar clones selected for phytoremediation of soils contaminated with heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Takacs, T.; Radimszky, L.; Nemeth, T. [Research Inst. for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Budapest (Hungary)

    2005-04-01

    The aim of this work was to study the colonization of indigenous arbuscular mycorrhizal fungi (AMF) species in fine-roots of poplar clones. Roots of 7 poplar clones were sampled from a 1-year-old trial established at an industrial site strongly polluted with heavy metals at Balatonfuezfoe, Hungary. The poplar clones have shown variable degrees of colonization by AMF, suggesting differential host susceptibility or mycorrhizal dependency. After outplanting the percentage of poplar survival was strongly correlated with the frequency of AMF infection. Two clones that survived at the lowest ratio after outplanting had not been colonized by AMF in contrast to those which survived to a much higher extent. (orig.)

  1. REFORMULATION OF COAL-DERIVED TRANSPORTATION FUELS: SELECTIVE OXIDATION OF CARBON MONOXIDE ON METAL FOAM CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Paul Chin; Xiaolei Sun; George W. Roberts; Amornmart Sirijarhuphan; Sourabh Pansare; James G. Goodwin Jr; Richard W. Rice; James J. Spivey

    2005-06-01

    Hydrocarbon fuels must be reformed in a series of steps to provide hydrogen for use in proton exchange membrane fuel cells (PEMFCs). Preferential oxidation (PROX) is one method to reduce the CO concentration to less than 10 ppm in the presence of {approx}40% H{sub 2}, CO{sub 2}, and steam. This will prevent CO poisoning of the PEMFC anode. Structured supports, such as ceramic monoliths, can be used for the PROX reaction. Alternatively, metal foams offer a number of advantages over the traditional ceramic monolith.

  2. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Memarzadeh, Kaveh [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Ren, Guogang [University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Allaker, Robert P., E-mail: r.p.allaker@qmul.ac.uk [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-10-01

    Objective: The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Methods: Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. Results: SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. Significance: The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. - Highlights: • Novel CoCrCu alloys were fabricated by using selective laser melting (SLM). • SLM CoCrCu alloys showed satisfied antimicrobial and antibiofilm activities. • SLM CoCrCu alloys have no cytotoxic effect on normal cells. • Other properties of SLM CoCrCu alloys were similar to SLM CoCr alloys. • SLM CoCrCu alloys have the potential to be used as coping metals.

  3. Direct Observation of Xe and Kr Adsorption in a Xe-Selective Microporous Metal-Organic Framework.

    Science.gov (United States)

    Chen, Xianyin; Plonka, Anna M; Banerjee, Debasis; Krishna, Rajamani; Schaef, Herbert T; Ghose, Sanjit; Thallapally, Praveen K; Parise, John B

    2015-06-10

    The cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal-organic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid-state adsorbents, but no experimental insights into the nature of the Xe-network interaction are available to date. Here we report a new microporous MOF (designated SBMOF-2) that is selective toward Xe over Kr under ambient conditions, with a Xe/Kr selectivity of about 10 and a Xe capacity of 27.07 wt % at 298 K. Single-crystal diffraction results show that the Xe selectivity may be attributed to the specific geometry of the pores, forming cages built with phenyl rings and enriched with polar -OH groups, both of which serve as strong adsorption sites for polarizable Xe gas. The Xe/Kr separation in SBMOF-2 was investigated with experimental and computational breakthrough methods. These experiments showed that Kr broke through the column first, followed by Xe, which confirmed that SBMOF-2 has a real practical potential for separating Xe from Kr. Calculations showed that the capacity and adsorption selectivity of SBMOF-2 are comparable to those of the best-performing unmodified MOFs such as NiMOF-74 or Co formate.

  4. Effective, Facile, and Selective Hydrolysis of the Chemical Warfare Agent VX Using Zr6-Based Metal-Organic Frameworks.

    Science.gov (United States)

    Moon, Su-Young; Wagner, George W; Mondloch, Joseph E; Peterson, Gregory W; DeCoste, Jared B; Hupp, Joseph T; Farha, Omar K

    2015-11-16

    The nerve agent VX is among the most toxic chemicals known to mankind, and robust solutions are needed to rapidly and selectively deactivate it. Herein, we demonstrate that three Zr6-based metal-organic frameworks (MOFs), namely, UiO-67, UiO-67-NH2, and UiO-67-N(Me)2, are selective and highly active catalysts for the hydrolysis of VX. Utilizing UiO-67, UiO-67-NH2, and UiO-67-N(Me)2 in a pH 10 buffered solution of N-ethylmorpholine, selective hydrolysis of the P-S bond in VX was observed. In addition, UiO-67-N(Me)2 was found to catalyze VX hydrolysis with an initial half-life of 1.8 min. This half-life is nearly 3 orders of magnitude shorter than that of the only other MOF tested to date for hydrolysis of VX and rivals the activity of the best nonenzymatic materials. Hydrolysis utilizing Zr-based MOFs is also selective and facile in the absence of pH 10 buffer (just water) and for the destruction of the toxic byproduct EA-2192.

  5. Metal contamination in select species of birds in Nilgiris district, Tamil Nadu, India.

    Science.gov (United States)

    Jayakumar, R; Muralidharan, S

    2011-08-01

    Variation in metal contamination in six species of birds, namely the Cormorant (Phalacrocorax carbo), Cattle Egret (Bubulcus ibis), Little Egret (Egretta garzetta), Pond Heron (Ardeola grayii), Common Myna (Acridotheres tristis) and Jungle Babbler (Turdoides striatus) in Nilgiris district, Tamil Nadu, India. The accumulation of heavy metals differed among the species studied. On an average, Little Egret accumulated high concentrations of copper (53.31 ± 23.19 ppm) followed by Cattle Egret (16.27 ± 9.83 ppm) in liver. Of all the species, Jungle Babbler recorded the maximum concentrations (20.59 ± 9.07 ppm) in muscle. The Pond Heron recorded the maximum concentration (35.38 ± 11.14 ppm) in brain. On an average the maximum level was in the kidney of Common Myna (7.76 ± 1.80 ppm).

  6. Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Mohamed Magdy; Radalla, Abd-Elatty; Qasem, Fatma; Khaled, Rehab [Beni-Suef University, Beni-Suef (Egypt)

    2014-01-15

    Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+} with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) .deg. C, and a constant ionic strength I=1x10{sup -1} mol L{sup -1} NaNO{sub 3} in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu{sup 2+}, Ni{sup 2+}, and Co{sup 2+} has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.

  7. Thermal analysis for laser selective removal of metallic single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jizhou, E-mail: jzsong@zju.edu.cn [Department of Engineering Mechanics and Soft Matter Research Center, Zhejiang University, Hangzhou 310027 (China); Li, Yuhang [The Solid Mechanics Research Center, Beihang University (BUAA), Beijing 100191 (China); Du, Frank; Xie, Xu; Rogers, John A. [Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Huang, Yonggang [Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-04-28

    Single-walled carbon nanotubes (SWNTs) have been envisioned as one of the best candidates for future semiconductors due to their excellent electrical properties and ample applications. However, SWNTs grow as mixture of both metallic and semiconducting tubes and this heterogeneity hampers their practical applications. Laser radiation shows promises to remove metallic SWNTs (m-SWNTs) in air under an appropriate condition. We established a scaling law, validated by finite element simulations, for the temperature rise of m-SWNTs under a pulsed laser with a Gaussian spot. It is shown that the maximum normalized m-SWNT temperature rise only depends on two non-dimensional parameters: the normalized pulse duration time and the normalized interfacial thermal resistance. In addition, the maximum temperature rise is inversely proportional to the square of spot size and proportional to the incident laser power. These results are very helpful to understand the underlying physics associated with the removal process and provides easily interpretable guidelines for further optimizations.

  8. Antioxidant, Metal Chelating, Anti-glucosidase Activities and Phytochemical Analysis of Selected Tropical Medicinal Plants.

    Science.gov (United States)

    Wong, Fai-Chu; Yong, Ann-Li; Ting, Evon Peir-Shan; Khoo, Sim-Chyi; Ong, Hean-Chooi; Chai, Tsun-Thai

    2014-01-01

    The purpose of this investigation was to determine the antioxidant potentials and anti-glucosidase activities of six tropical medicinal plants. The levels of phenolic constituents in these medicinal plants were also quantified and compared. Antioxidation potentials were determined colorimetrically for scavenging activities against DPPH and NO radicals. Metal chelating assay was based on the measurement of iron-ferrozine absorbance at 562 nm. Anti-diabetic potentials were measured by using α-glucosidase as target enzyme. Medicinal plants' total phenolic, total flavonoid and hydroxycinnamic acid contents were determined using spectrophotometric methods, by comparison to standard plots prepared using gallic acid, quercetin and caffeic acid standards, respectively. Radical scavenging and metal chelating activities were detected in all medicinal plants, in concentration-dependent manners. Among the six plants tested, C. nutans, C. formosana and H. diffusa were found to possess α-glucosidase inhibitory activities. Spectrophotometric analysis indicated that the total phenolic, total flavonoid and hydroxycinnamic acid contents ranged from 12.13-21.39 mg GAE per g of dry sample, 1.83-9.86 mg QE per g of dry sample, and 0.91-2.74 mg CAE per g of dry sample, respectively. Our results suggested that C. nutans and C. formosana could potentially be used for the isolation of potent antioxidants and anti-diabetic compounds. To the best of our knowledge, this study represents the first time that C. nutans (Acanthaceae family) was reported in literature with glucosidase inhibition activity.

  9. Selective Uptake of Alkaline Earth Metals by Cyanobacteria Forming Intracellular Carbonates.

    Science.gov (United States)

    Cam, Nithavong; Benzerara, Karim; Georgelin, Thomas; Jaber, Maguy; Lambert, Jean-François; Poinsot, Mélanie; Skouri-Panet, Fériel; Cordier, Laure

    2016-11-01

    The uptakes of calcium (Ca), strontium (Sr), and barium (Ba) by two cyanobacterial strains, Cyanothece sp. PCC7425 and Gloeomargarita lithophora, both forming intracellular carbonates, were investigated in laboratory cultures. In the culture medium BG-11 amended with 250 μM Ca and 50 or 250 μM Sr and Ba, G. lithophora accumulated first Ba, then Sr, and finally Ca. Sr and Ba were completely accumulated by G. lithophora cells at rates between 0.02 and 0.10 fmol h(-1) cell(-1) and down to extracellular concentrations below the detection limits of inductively coupled plasma atomic emission spectroscopy. Accumulation of Sr and Ba did not affect the growth rate of the strain. This sequential accumulation occurred mostly intracellularly within polyphosphate and carbonate granules and resulted in the formation of core-shell structures in carbonates. In contrast, Cyanothece sp. PCC7425 showed neither a preferential accumulation of heavier alkaline earth metals nor core-shell structures in the carbonates. This indicated that fractionation between alkaline earth metals was not inherent to intracellularly calcifying cyanobacteria but was likely a genetically based trait of G. lithophora. Overall, the capability of G. lithophora to sequester preferentially Sr and Ba at high rates may be of considerable interest for designing new remediation strategies and better understanding the geochemical cycles of these elements.

  10. High spectral selectivity for solar absorbers using a monolayer transparent conductive oxide coated on a metal substrate

    Science.gov (United States)

    Shimizu, Makoto; Suzuki, Mari; Iguchi, Fumitada; Yugami, Hiroo

    2017-05-01

    A spectrally selective absorber composed of a monolayer transparent conductive oxide (TCO) coated on a metal substrate is investigated for use in solar systems operating at temperatures higher (>973 K) than the operation temperature of conventional systems ( ˜ 673 K). This method is different from the currently used solar-selective coating technologies, such as those using multilayered and cermet materials. The spectral selective absorption property can be attributed to the inherent optical property of TCO owing to the plasma frequency and interferences between the substrates. Since spectral selectivity can be achieved using monolayered materials, the effect of atomic diffusion occurring at each layer boundary in a multilayer or cermet coatings under high-temperature conditions can be reduced. In addition, since this property is attributed to the inherent property of TCO, the precise control of the layer thickness can be omitted if the layer is sufficiently thick (>0.5 μm). The optimum TCO properties, namely, carrier density and mobility, required for solar-selective absorbers are analyzed to determine the cutoff wavelength and emittance in the infrared range. A solar absorptance of 0.95 and hemispherical emittance of 0.10 at 973 K are needed for achieving the optimum TCO properties, i.e., a carrier density of 5.5 × 1020 cm-3 and mobility of 90 cm2 V-1 s-1 are required. Optical simulations indicate that the spectrally selective absorption weakly depends on the incident angle and film thickness. The thermal stability of the fabricated absorber treated at temperatures up to 973 K for 10 h is verified in vacuum by introducing a SiO2 interlayer, which plays an important role as a diffusion barrier.

  11. Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

    Institute of Scientific and Technical Information of China (English)

    V.H.Rane; S.T.Chaudhari; V.R.Choudhary

    2008-01-01

    Surface properties (viz. surface area, basicity/base strength distribution, and crystal phases) of alkali metal doped CaO (alkali metal/Ca = 0.1 and 0.4) catalysts and their catalytic activity/selectivity in oxidative coupling of methane (OCM) to higher hydrocarbons at different reaction conditions (viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm3·g-1·h-1) have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties (viz. surface area, basicity/base strength distribution) and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity (strong basic sites) and the C2+ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO (Na/Ca = 0.1, before calcination) catalyst (calcined at 750 ℃), showed best performance (C2+selectivity of 68.8% with 24.7% methane conversion), whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

  12. Functional Determinants of Metal Ion Transport and Selectivity in Paralogous Cation Diffusion Facilitator Transporters CzcD and MntE in Streptococcus pneumoniae.

    Science.gov (United States)

    Martin, Julia E; Giedroc, David P

    2016-01-19

    Cation diffusion facilitators (CDFs) are a large family of divalent metal transporters that collectively possess broad metal specificity and contribute to intracellular metal homeostasis and virulence in bacterial pathogens. Streptococcus pneumoniae expresses two homologous CDF efflux transporters, MntE and CzcD. Cells lacking mntE or czcD are sensitive to manganese (Mn) or zinc (Zn) toxicity, respectively, and specifically accumulate Mn or Zn, respectively, thus suggesting that MntE selectively transports Mn, while CzcD transports Zn. Here, we probe the origin of this metal specificity using a phenotypic growth analysis of pneumococcal variants. Structural homology to Escherichia coli YiiP predicts that both MntE and CzcD are dimeric and each protomer harbors four pairs of conserved metal-binding sites, termed the A site, the B site, and the C1/C2 binuclear site. We find that single amino acid mutations within both the transmembrane domain A site and the B site in both CDFs result in a cellular metal sensitivity similar to that of the corresponding null mutants. However, multiple mutations in the predicted cytoplasmic C1/C2 cluster of MntE have no impact on cellular Mn resistance, in contrast to the analogous substitutions in CzcD, which do have on impact on cellular Zn resistance. Deletion of the MntE-specific C-terminal tail, present only in Mn-specific bacterial CDFs, resulted in only a modest growth phenotype. Further analysis of MntE-CzcD functional chimeric transporters showed that Asn and Asp in the ND-DD A-site motif of MntE and the most N-terminal His in the HD-HD site A of CzcD (the specified amino acids are underlined) play key roles in transporter metal selectivity. Cation diffusion facilitator (CDF) proteins are divalent metal ion transporters that are conserved in organisms ranging from bacteria to humans and that play important roles in cellular physiology, from metal homeostasis and resistance to type I diabetes in vertebrates. The respiratory

  13. Exploiting Framework Flexibility of a Metal-Organic Framework for Selective Adsorption of Styrene over Ethylbenzene

    NARCIS (Netherlands)

    Mukherjee, S.; Joarder, B.; Desai, A.V.; Manna, B.; Krishna, R.; Ghosh, S.K.

    2015-01-01

    The separation of styrene and ethylbenzene mixtures is industrially important and is currently performed in highly energy-intensive vacuum distillation columns. The primary objective of our investigation is to offer an energy-efficient alternative for selective adsorption of styrene by a flexible me

  14. A metal ion charged mixed matrix membrane for selective adsorption of hemoglobin

    NARCIS (Netherlands)

    Tetala, K.K.R.; Skrzypek, K.; Levisson, M.; Stamatialis, D.F.

    2013-01-01

    In this work, we developed a mixed matrix membrane by incorporating 20–40 µm size iminodiacetic acid modified immobeads within porous Ethylene vinyl alcohol (EVAL) polymer matrix. The MMM were charged with copper ions for selective adsorption of bovine hemoglobin in presence of bovine serum albumin.

  15. Carbon nanotube diameter selection by pretreatment of metal catalysts on surfaces

    Science.gov (United States)

    Hauge, Robert H [Houston, TX; Xu, Ya-Qiong [Houston, TX; Shan, Hongwei [Houston, TX; Nicholas, Nolan Walker [South Charleston, WV; Kim, Myung Jong [Houston, TX; Schmidt, Howard K [Cypress, TX; Kittrell, W Carter [Houston, TX

    2012-02-28

    A new and useful nanotube growth substrate conditioning processes is herein disclosed that allows the growth of vertical arrays of carbon nanotubes where the average diameter of the nanotubes can be selected and/or controlled as compared to the prior art.

  16. Exploiting Framework Flexibility of a Metal-Organic Framework for Selective Adsorption of Styrene over Ethylbenzene

    NARCIS (Netherlands)

    Mukherjee, S.; Joarder, B.; Desai, A.V.; Manna, B.; Krishna, R.; Ghosh, S.K.

    2015-01-01

    The separation of styrene and ethylbenzene mixtures is industrially important and is currently performed in highly energy-intensive vacuum distillation columns. The primary objective of our investigation is to offer an energy-efficient alternative for selective adsorption of styrene by a flexible

  17. Deoxygenation of benzoic acid on metal oxides. I. The selective pathway to benzaldehyde

    NARCIS (Netherlands)

    Lange, de M.W.; Ommen, van J.G.; Lefferts, L.

    2001-01-01

    The mechanism of the selective deoxygenation of benzoic acid to benzaldehyde was studied on ZnO and ZrO2. The results show conclusively that the reaction proceeds as a reverse type of Mars and van Krevelen mechanism consisting of two steps: hydrogen activates the oxide by reduction resulting in the

  18. Sobredentadura total superior implantosoportada

    Directory of Open Access Journals (Sweden)

    Luis Orlando Rodríguez García

    2010-06-01

    Full Text Available Se presenta un caso de un paciente desdentado total superior, rehabilitado en la consulta de implantología de la Clínica "Pedro Ortiz" del municipio Habana del Este en Ciudad de La Habana, Cuba, en el año 2009, mediante prótesis sobre implantes osteointegrados, técnica que se ha incorporado a la práctica estomatológica en Cuba como alternativa al tratamiento convencional en los pacientes desdentados totales. Se siguió un protocolo que comprendió una fase quirúrgica, procedimiento con o sin realización de colgajo y carga precoz o inmediata. Se presenta un paciente masculino de 56 años de edad, que acudió a la consulta multidisciplinaria, preocupado, porque se le habían elaborado tres prótesis en los últimos dos años y ninguna reunía los requisitos de retención que él necesitaba para sentirse seguro y cómodo con las mismas. El resultado final fue la satisfacción total del paciente, con el mejoramiento de la calidad estética y funcional.

  19. 马尾松高产脂优良家系及优树选择研究%The selection of high resinyield family and superior individual of Pinus massoniana

    Institute of Scientific and Technical Information of China (English)

    黄帆; 陈清新; 周国瑾

    2015-01-01

    以试管式松脂收集法对城步县32年生马尾松子代测定林的80个家系进行调查分析。发现马尾松家系内产脂量差异显著,湖南省内马尾松家系明显高于湖南省外家系,湖南省内平均产脂量是湖南省外平均产脂量的2倍。生长性状中胸径与马尾松产脂量相关系数为0.440,枝下高为-0.002,在生长性状中胸径与产脂量相关系数最高,枝下高与产脂量相关性较小。本文根据产脂量选择优良家系,共选出20株湖南省外优树,16株湖南省内优树。%Through the investigation and analysis of 80 families of filial generation 32-year-old testing forests of Pinus massoniana in Chengbu County by tube type resin collection method.The resin yield of P.massoniana is significant difference,and resin yield in Hunan Provincewas significantly higher than it of other provinces,the average resin yield in Hunan Province is 2 times than it of the other provinces.The correlation coefficient between theresin yield with character DBH and height of the branch was 0.440 and -0.002 respectively.The highest correlation coefficient is DBH,and lowest is height of the branch.Based on resin producing capacities,20 superior individual of outside Hunan Province and 16 in-side were selected.

  20. Novel conductometric biosensor based on three-enzyme system for selective determination of heavy metal ions.

    Science.gov (United States)

    Soldatkin, O O; Kucherenko, I S; Pyeshkova, V M; Kukla, A L; Jaffrezic-Renault, N; El'skaya, A V; Dzyadevych, S V; Soldatkin, A P

    2012-02-01

    A differential pair of planar thin-film interdigitated electrodes, deposited on a ceramic pad, was used as a conductometric transducer. The three-enzyme system (invertase, mutarotase, glucose oxidase), immobilized on the transducer surface, was used as a bioselective element. The ratio between enzymes in the membrane was found experimentally considering the highest biosensor sensitivity to substrate (sucrose) and heavy metal ions. Optimal concentration of sucrose for inhibitory analysis was 1.25 mM and incubation time in the investigated solution amounted to 10-20 min. The developed biosensor demonstrated the best sensitivity toward ions Hg(2+) and Ag(+). A principal possibility of the biosensor reactivation either by EDTA solution after inhibition with silver ions or by cysteine solution after inhibition with mercury ions was shown.

  1. Influence of selected rare earth metals on structural characteristics of 42CrMo4 steel

    Directory of Open Access Journals (Sweden)

    J. Drápala

    2016-10-01

    Full Text Available The influence of rare earth metals (REM addition on solidification structure of the low-carbon 42CrMo4 steel was investigated. Alloys were prepared by means of a centrifugal casting. The addition of cerium, praseodymium or mischmetal in the steel produced greatly improved solidification structure with a suppressed columnar grain zone, finer grain size in the equiaxed grain zone. The additions occurred in the steel bath in the form of REM oxide and/or oxide-sulphide inclusions and as dissolved REM segregated along with other elements at prior grain boundaries and interdendritic spaces. Microstructure (light microscope, SEM/EDX chemical microanalysis, and TOF-SIMS analysis – mapping of elements in the structure of alloys were obtained.

  2. Water quality in the Tibetan Plateau: Metal contents of four selected rivers

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xiang [Laboratory of Applied Environmental Chemistry, University of Kuopio, Patteristonkatu 1, FIN-50100 Mikkeli (Finland); Department of Chemistry and Environmental Sciences, Tibet University, No. 36 Jiangsu Lu, Lhasa, T.A.R. 850000 (China)], E-mail: xiang.huang@uku.fi; Sillanpaeae, Mika [Laboratory of Applied Environmental Chemistry, University of Kuopio, Patteristonkatu 1, FIN-50100 Mikkeli (Finland)], E-mail: mika.sillanpaa@uku.fi; Duo Bu [Department of Chemistry and Environmental Sciences, Tibet University, No. 36 Jiangsu Lu, Lhasa, T.A.R. 850000 (China)], E-mail: pudorr@yahoo.com.cn; Gjessing, Egil T. [Department of Chemistry, University of Oslo, P.O. Box 1033, Oslo 0315 (Norway)], E-mail: egil.gjessing@kjemi.uio.no

    2008-11-15

    The water used by 85% of the Asian population originates in Tibetan Plateau. During April and May of 2006, water samples were collected from four major Asian rivers in the Plateau (i.e. the Salween, Mekong, Yangtze River and Yarlung Tsangpo) and analyzed for Cu, Pb, Zn, Ag, Mo, Cd, Co, Cr, Ni, Li, Mn, Al, Fe, Mg and Hg. The results showed that elements such as Mg were rather high in Tibetan rivers, giving a mean electrical conductance of 36 mS/m. In a few locations, the results also showed relatively high concentrations of Al and Fe (>1 mg/L). However, the concentrations of Cu, Zn, Ag, Cd, and Cr were generally low. Contamination with Pb was identified at a few locations in the Salween and Ni at a few sites in the Yangtze River. - For the first time, total dissolved metal contents in source water of four major Asian rivers were evaluated at the same time.

  3. Luminescent Lanthanide Metal Organic Frameworks for cis-Selective Isoprene Polymerization Catalysis

    Directory of Open Access Journals (Sweden)

    Samantha Russell

    2015-11-01

    Full Text Available In this study, we are combining two areas of chemistry; solid-state coordination polymers (or Metal-Organic Framework—MOF and polymerization catalysis. MOF compounds combining two sets of different lanthanide elements (Nd3+, Eu3+/Tb3+ were used for that purpose: the use of neodymium was required due to its well-known catalytic properties in dienes polymerization. A second lanthanide, europium or terbium, was included in the MOF structure with the aim to provide luminescent properties. Several lanthanides-based MOF meeting these criteria were prepared according to different approaches, and they were further used as catalysts for the polymerization of isoprene. Stereoregular cis-polyisoprene was received, which in some cases exhibited luminescent properties in the UV-visible range.

  4. Impact of mineral components and selected trace metals on ambient PM10 concentrations

    Science.gov (United States)

    Limbeck, Andreas; Handler, Markus; Puls, Christoph; Zbiral, Johannes; Bauer, Heidi; Puxbaum, Hans

    PM10 levels of the mineral components Si, Al, Fe, Ca, Mg and some trace metals were measured at three different sites in the urban area of Vienna (Austria). Observed trace metal concentrations varied between less than 0.1 ng m -3 (Cd) and approximately 200 ng m -3 (Zn), mineral components showed enhanced concentrations ranging from 0.01 μg m -3 (Ca) to 16.3 μg m -3 (Si). The contribution of the respective mineral oxides to PM10 mass concentrations accounted on average for 26.4 ± 16% (n = 1090) of the PM10 mass, with enhanced rates in spring and autumn (monthly averages of up to 40%) and decreased contributions in the cold season (monthly averages below 10%). The atmospheric occurrence of Al, Ti and Sr could be assigned to crustal sources, whereas for the elements Ba, Ca, Fe, Mg, Mn and V an increased contribution of non-crustal origin was observed. PM10 levels of As, Cd, Co, Cr, Cu, Ni, Pb, Sb, Sn and Zn were predominantly derived from man-made emissions. Intersite comparison indicated that urban PM10 mass concentrations and PM10 levels of As, Pb and Zn were predominantly influenced from the transport of aerosols from outside into the city, whereas for the elements Ba, Mg, Ca, Cu and Fe a distinctly increased impact of local emissions was observed. The contribution of these urban emissions to total PM10 concentrations was estimated by calculating the so-called "urban impact", which was found to be 32.7 ± 18% (n = 392) in the case of PM10 mass concentrations. The investigated elements accounted on average for 31.3 ± 19% (n = 392) of the observed PM10 mass increase. The mean values for the "urban impacts" of individual elements varied between 25.5% (As) and 77.0% (Ba).

  5. REFORMULATION OF COAL-DERIVED TRANSPORTATION FUELS: SELECTIVE OXIDATION OF CARBON MONOXIDE ON METAL FOAM CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Mr. Paul Chin; Dr. Xiaolei Sun; Professor George W. Roberts; Professor James J. Spivey; Mr. Amornmart Sirijarhuphan; Dr. James G. Goodwin, Jr.; Dr. Richard W. Rice

    2002-12-31

    Several different catalytic reactions must be carried out in order to convert hydrocarbons (or alcohols) into hydrogen for use as a fuel for polyelectrolyte membrane (PEM) fuel cells. Each reaction in the fuel-processing sequence has a different set of characteristics, which influences the type of catalyst support that should be used for that particular reaction. A wide range of supports are being evaluated for the various reactions in the fuel-processing scheme, including porous and non-porous particles, ceramic and metal straight-channel monoliths, and ceramic and metal monolithic foams. These different types of support have distinctly different transport characteristics. The best choice of support for a given reaction will depend on the design constraints for the system, e.g., allowable pressure drop, and on the characteristics of the reaction for which the catalyst is being designed. Three of the most important reaction characteristics are the intrinsic reaction rate, the exothermicity/endothermicity of the reaction, and the nature of the reaction network, e.g., whether more than one reaction takes place and, in the case of multiple reactions, the configuration of the network. Isotopic transient kinetic analysis was used to study the surface intermediates. The preferential oxidation of low concentrations of carbon monoxide in the presence of high concentrations of hydrogen (PROX) is an important final step in most fuel processor designs. Data on the behavior of straight-channel monoliths and foam monolith supports will be presented to illustrate some of the factors involved in choosing a support for this reaction.

  6. Effect of the selective pressure of sub-lethal level of heavy metals on the fate and distribution of ARGs in the catchment scale.

    Science.gov (United States)

    Xu, Yan; Xu, Jian; Mao, Daqing; Luo, Yi

    2017-01-01

    Our previous study demonstrated that high levels of antibiotic resistance genes (ARGs) in the Haihe River were directly attributed to the excessive use of antibiotics in animal agriculture. The antibiotic residues of the Xiangjiang River determined in this study were much lower than those of the Haihe River, but the relative abundance of 16 detected ARGs (sul1, sul2 and sul3, qepA, qnrA, qnrB, qnrD and qnrS, tetA, tetB, tetW, tetM, tetQ and tetO, ermB and ermC), were as high as the Haihe River particularly in the downstream of the Xiangjiang River which is close to the extensive metal mining. The ARGs discharged from the pharmaceutical wastewater treatment plant (PWWTP) are a major source of ARGs in the upstream of the Xiangjiang River. In the downstream, selective stress of heavy metals rather than source release had a significant influence on the distinct distribution pattern of ARGs. Some heavy metals showed a positive correlation with certain ARG subtypes. Additionally, there is a positive correlation between individual ARG subtypes and heavy metal resistance genes, suggesting that heavy metals may co select the ARGs on the same plasmid of antibiotic resistant bacteria. The co-selection mechanism between specific metal and antibiotic resistance was further confirmed by these isolations encoding the resistance genotypes to antibiotics and metals. To our knowledge, this is the first study on the fate and distribution of ARGs under the selective pressure exerted by heavy metals in the catchment scale. These results are beneficial to understand the fate, and to discern the contributors of ARGs from either the source release or the selective pressure by sub-lethal levels of environmental stressors during their transport on a river catchment scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Platinum Metal-Free Catalysts for Selective Soft Oxidative Methane → Ethylene Coupling. Scope and Mechanistic Observations.

    Science.gov (United States)

    Peter, Matthias; Marks, Tobin J

    2015-12-09

    Using abundant soft oxidants, a high methane-to-ethylene conversion might be achievable due to the low thermodynamic driving force for over-oxidation. Here we report on the oxidative coupling of methane by gaseous S2 (SOCM). The catalytic properties of Pd/Fe3O4 are compared with those of Fe3O4, and it is found that high ethylene selectivities can be achieved without noble metals; conversion and selectivity on Fe3O4 are stable for at least 48 h at SOCM conditions. SOCM data for 10 oxides are compared, and ethylene selectivities as high as 33% are found; the C2H4/C2H6 ratios of 9-12 observed at the highest S2 conversions are significantly higher than the C2H4/C2H6 ratios usually found in the CH4 coupling with O2. Complementary in-detail analytical studies show that, on Mg, Zr, Sm, W, and La catalysts, which strongly coke during the reaction, lower ethylene selectivities are observed than on Fe, Ti, and Cr catalysts, which only coke to a minor extent. Further catalyst-dependent changes during SOCM in surface area, surface composition, and partial conversion to oxysulfides and sulfides are discussed. Evidence concerning the reaction mechanism is obtained taking into account the selectivity for the different reaction products versus the contact time. CH4 coupling proceeds non-oxidatively with the evolution of H2 on some catalysts, and evidence is presented that C2H4 and C2H2 formation occur via C2H6 and C2H4 dehydrogenation, respectively.

  8. Catalyses of Metals and TheirSulfides in Selective Hydrogenation of 9, 10-Diphenyl anthracene

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Catalytic hydrogenation and hydrocracking of 9,10-diphenylanthracene (9,10-DPA) , used as a coal-re-lated model compound, was investigated at a relatively low temperature. The results show that the Fe and Ni main-ly catalyze non-ipso hydrogenation of 9,10-DPA without sulfur, but selectively promote ipso hydrogenation of 9,10-DPA in the presence of sulfur.

  9. Ab initio study of MgH2: Destabilizing effects of selective substitutions by transition metals

    Science.gov (United States)

    Al Alam, Adel F.; Matar, Samir F.; Ouaini, Naïm

    2014-10-01

    The strong ionicity of H within rutile MgH2 is reduced by selective substitution of Mg by T (=Fe, Co, Ni, Pd, Pt) using trirutile super-structure host TMg2H6. These novel model systems, as computed in the quantum mechanical framework of density functional theory, showed a gradual decrease of the charges carried by H down to -0.02e improving the use of MgH2 for applications.

  10. Adsorption of heavy metal cations by Na-clinoptilolite: equilibrium and selectivity studies.

    Science.gov (United States)

    Mihaly-Cozmuta, L; Mihaly-Cozmuta, A; Peter, A; Nicula, C; Tutu, H; Silipas, Dan; Indrea, Emil

    2014-05-01

    This paper summarizes the conclusions of experiments conducted on the adsorption of Cd(2+), Co(2+), Cu(2+), Mn(2+), Ni(2+), Pb(2+) and Zn(2+) onto zeolite. The focus of the experiments was to establish the influence of the initial pH of the contact solution as well as the selectivity of zeolite on the efficiency of the adsorption process. To this end, experimental adsorption isotherms were established for the pH values ranging from 1 to 4 by using the Na-form of clinoptilolite (particle size range 0.5-1 mm) as an adsorbent. Langmuir, Freundlich and Dubinin-Raduschkevich isotherm models were used to validate the experimental data and the Gibbs free energy was calculated based on the distribution coefficient. From the Langmuir model, correlations between the maximum adsorption capacity and selected physical-chemical parameters of the cations studied were established. The results of the experiments suggest that the selectivity of zeolite is strongly influenced by the pH of the contact solution, dehydration energy of cations, diffusion coefficient and the pH at which the precipitation of hydroxides occurs.

  11. Postsynthesis-Treated Iron-Based Metal-Organic Frameworks as Selective Catalysts for the Sustainable Synthesis of Nitriles.

    Science.gov (United States)

    Rapeyko, Anastasia; Climent, Maria J; Corma, Avelino; Concepción, Patricia; Iborra, Sara

    2015-10-12

    The dehydration of aldoximes to the corresponding nitriles can be performed with excellent activity and selectivity by using iron trimesate as a homogeneous catalyst. Iron trimesate has been heterogenized by synthesizing metal-organic frameworks (MOFs) from iron trimesate, that is, Fe(BTC), and MIL-100 (Fe). These materials were active and selective aldoxime dehydration catalysts, and postsynthesis-treated MIL-100 (Fe) produced the desired nitriles with 100 % conversion and selectivities >90 % under mild reaction conditions and in short reaction times. X-ray photoelectron spectroscopy showed the presence of different Fe species in the catalyst, and in situ IR spectroscopy combined with catalytic results indicates that the catalytic activity is associated with Fe framework species. The postsynthesis-treated MIL-100 (Fe)-NH4 F can be recycled several times and has an excellent reaction scope, which gives better catalytic results than other solid acid or base catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Selective CO Methanation on Ru/TiO2 Catalysts: Role and Influence of Metal-Support Interactions

    DEFF Research Database (Denmark)

    Abdel-Mageed, Ali M.; Widmann, D.; Olesen, Sine Ellemann

    2015-01-01

    Aiming at a detailed understanding of the role of metal-support interactions in the selective methanation of CO in CO2-rich reformate gases, we have investigated the catalytic performance of a set of Ru/TiO2 catalysts with comparable Ru loading, Ru particle size, and TiO2 phase composition but very...... different surface areas (ranging from 20 to 235 m2 g-1) in this reaction. The activity for CO methanation, under steady-state conditions, was found to strongly depend on the TiO2 support surface area, increasing first with increasing surface area up to a maximum activity for the Ru/TiO2 catalyst...... with a surface area of 121 m2 g-1 and then decreasing for an even higher surface area; however, the selectivity is mainly determined by the Ru particle size, which slightly decreases with increasing support surface area. This goes along with an increase in selectivity for CO methanation, in agreement...

  13. Investigations into Recycling Zinc from Used Metal Oxide Varistors via pH Selective Leaching: Characterization, Leaching, and Residue Analysis

    Directory of Open Access Journals (Sweden)

    Toni Gutknecht

    2015-01-01

    Full Text Available Metal oxide varistors (MOVs are a type of resistor with significantly nonlinear current-voltage characteristics commonly used in power lines to protect against overvoltages. If a proper recycling plan is developed MOVs can be an excellent source of secondary zinc because they contain over 90 weight percent zinc oxide. The oxides of antimony, bismuth, and to a lesser degree cobalt, manganese, and nickel are also present in varistors. Characterization of the MOV showed that cobalt, nickel, and manganese were not present in the varistor material at concentrations greater than one weight percent. This investigation determined whether a pH selective dissolution (leaching process can be utilized as a starting point for hydrometallurgical recycling of the zinc in MOVs. This investigation showed it was possible to selectively leach zinc from the MOV without coleaching of bismuth and antimony by selecting a suitable pH, mainly higher than 3 for acids investigated. It was not possible to leach zinc without coleaching of manganese, cobalt, and nickel. It can be concluded from results obtained with the acids used, acetic, hydrochloric, nitric, and sulfuric, that sulfate leaching produced the most desirable results with respect to zinc leaching and it is also used extensively in industrial zinc production.

  14. Removal of hazardous organics from water using metal-organic frameworks (MOFs): plausible mechanisms for selective adsorptions.

    Science.gov (United States)

    Hasan, Zubair; Jhung, Sung Hwa

    2015-01-01

    Provision of clean water is one of the most important issues worldwide because of continuing economic development and the steady increase in the global population. However, clean water resources are decreasing everyday, because of contamination with various pollutants including organic chemicals. Pharmaceutical and personal care products, herbicides/pesticides, dyes, phenolics, and aromatics (from sources such as spilled oil) are typical organics that should be removed from water. Because of their huge porosities, designable pore structures, and facile modification, metal-organic frameworks (MOFs) are used in various adsorption, separation, storage, and delivery applications. In this review, the adsorptive purifications of contaminated water with MOFs are discussed, in order to understand possible applications of MOFs in clean water provision. More importantly, plausible adsorption or interaction mechanisms and selective adsorptions are summarized. The mechanisms of interactions such as electrostatic interaction, acid-base interaction, hydrogen bonding, π-π stacking/interaction, and hydrophobic interaction are discussed for the selective adsorption of organics over MOFs. The adsorption mechanisms will be very helpful not only for understanding adsorptions but also for applications of adsorptions in selective removal, storage, delivery and so on.

  15. Devitrification kinetics and phase selection mechanisms in Cu-Zr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Ilkay [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Metallic glasses have been a promising class of materials since their discovery in the 1960s. Indeed, remarkable chemical, mechanical and physical properties have attracted considerable attention, and several excellent reviews are available. Moreover, the special group of glass forming alloys known as the bulk metallic glasses (BMG) become amorphous solids even at relatively low cooling rates, allowing them to be cast in large cross sections, opening the scope of potential applications to include bulk forms and net shape structural applications. Recent studies have been reported for new bulk metallic glasses produced with lower cooling rates, from 0.1 to several hundred K/s. Some of the application products of BMGs include sporting goods, high performance springs and medical devices. Several rapid solidification techniques, including melt-spinning, atomization and surface melting have been developed to produce amorphous alloys. The aim of all these methods is to solidify the liquid phase rapidly enough to suppress the nucleation and growth of crystalline phases. Furthermore, the production of amorphous/crystalline composite (ACC) materials by partial crystallization of amorphous precursor has recently given rise to materials that provide better mechanical and magnetic properties than the monolithic amorphous or crystalline alloys. In addition, these advances illustrate the broad untapped potential of using the glassy state as an intermediate stage in the processing of new materials and nanostructures. These advances underlie the necessity of investigations on prediction and control of phase stability and microstructural dynamics during both solidification and devitrification processes. This research presented in this dissertation is mainly focused on Cu-Zr and Cu-Zr-Al alloy systems. The Cu-Zr binary system has high glass forming ability in a wide compositional range (35-70 at.% Cu). Thereby, Cu-Zr based alloys have attracted much attention according to fundamental

  16. Oral bioavailability of arsenic, antimony and a selection of metals in ashes; Oral biotillgaenglighet av arsenik, antimon och ett urval av metaller i askor

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Christel; Bendz, David; Jones, Celia

    2008-06-15

    In an earlier study, financed by Varmeforsk, 'Q4-238 Environmental guidelines for reuse of ash in civil engineering applications', the total content of arsenic and lead was shown to determine whether or not reuse of some of the ashes in construction work is feasible. The model used to calculate the guidelines uses the total concentration of metals to evaluate the health risks resulting from exposure to the ashes. The use of total concentration can lead to overly conservative risk assessments if a significant fraction of the total metal content is not bioavailable. Better precision in the risk assessment can be given by the use of the bioavailable fraction of arsenic and lead in the model. As a result, ashes which are rejected on the basis of total metal concentration may be acceptable for use in engineering construction when the assessment is based on the bioavailable fraction. The purpose of the study was to (i) compile information on the oral bioavailability of arsenic, antimony and a selection of metals in ashes and similar materials, and on in vitro methods for determination of oral bioavailability, and (ii) experimentally estimate oral bioavailability of arsenic, antimony and some metals in a selection of ashes by analysis of the gastrointestinal bioaccessibility of these elements. The investigated elements were antimony, arsenic, lead, cadmium, copper, chromium, nickel and zinc. In the literature study performed within the project a number of static and dynamic in vitro methods simulating gastrointestinal processes of contaminants were compiled. The methods include one or several segments, i.e. mouth, stomach and intestine. Among the compiled methods, the RIVM (Rijksinstituut voor volksgesundheid en milieu) in vitro method was used in the experimental part of the project. The advantages with the method was that: the method to a high degree mimicked the human gastrointestinal processes (the method included three segments mouth, stomach, and intestine

  17. MODIFICATION OF KELUD VOLCANIC ASH 2014 AS SELECTIVE ADSORBENT MATERIAL FOR COPPER(II METAL ION

    Directory of Open Access Journals (Sweden)

    Susila Kristianingrum

    2017-01-01

      This research aims to prepare an adsorbent from Kelud volcanic ash for better Cu(II adsorption efficiency than Kiesel gel 60G E'Merck. Adsorbent synthesis was done by dissolving 6 grams of volcanic ash activated 700oC 4 hours and washed with HCl 0.1 M into 200 ml of 3M sodium hydroxide with stirring and heating of 100 °C for 1 hour. The filtrate sodium silicate was then neutralized using sulfuric acid. The mixture was allowed to stand for 24 hours then filtered and washed with aquaDM, then dried and crushed. The procedure is repeated for nitric acid, acetic acid and formic acid with a contact time of 24 hours. The products were then characterized using FTIR and XRD, subsequently determined acidity, moisture content, and tested for its adsorption of the ion Cu (II with AAS. The results showed that the type of acid that produced highest rendemen is AK-H2SO4-3M ie 36.93%, acidity of the adsorbent silica gel synthesized similar to Kiesel gel 60G E'Merck ie adsorbent AK-CH3COOH-3M and the water content of the silica gel adsorbent synthesized similar to Kiesel gel 60G E'Merck ie adsorbent AK-H2SO4-2 M. The character of the functional groups of silica gel synthesized all have similarities with Kiesel gel 60G E'Merck as a comparison. Qualitative analysis by XRD for all modified adsorbent showed a dominant peak of SiO2 except adsorbent AK-H2SO4 amorphous and chemical bonds with FTIR indicates that it has formed a bond of Si-O-Si and Si-OH. The optimum adsorption efficiency of the metal ions Cu(II obtained from AK-H2SO4-5M adsorbent that is equal to 93.2617% and the optimum adsorption capacity of the Cu(II metal ions was obtained from the adsorbent AK-CH3COOH-3M is equal to 2.4919 mg/ g.   Keywords: adsorbents, silica gel, adsorption, kelud volcanic ash

  18. The Relationship Between Perceived Influence Measures and Member Attitudes of (A) Policy Agreement, (B) Superior-Subordiante Relations, and (C) Peer Relations in Selected Community College Departments in Maryland -- A Summary.

    Science.gov (United States)

    Cook, Gordon

    An investigation was made of influence in 77 academic departments of 11 community colleges in Maryland. The purposes of the investigation were to examine the relationship of perceived measures of influence to member attitudes of (a) policy agreement, (b) superior-subordinate relations, (c) peer relations; to examine the aslopes of the distribution…

  19. Multi-signaling thiocarbohydrazide based colorimetric sensors for the selective recognition of heavy metal ions in an aqueous medium

    Science.gov (United States)

    Momidi, Bharath Kumar; Tekuri, Venkatadri; Trivedi, Darshak R.

    2017-06-01

    A series of colorimetric chemosensors R1-R6 have been developed from thiocarbohydrazide derivatives, for the selective detection of heavy metal ions. The structures of the receptors R1-R6 were well characterized by standard spectroscopic techniques like FT-IR, 1H NMR, and ESI-MS. The solid structure of receptor R1 and R2 were derived by single crystal X-ray diffraction (SC-XRD). The cation reorganization abilities of receptors R1-R6 were studied by UV-Vis spectroscopy. The receptors R1, R3 and R4 acts as a tremendous sensitive probe for heavy metal ions (Hg2 +, Cd2 + and Pb2 +) with the μM detection (R1 for Hg2 +, 2.72, R3 for Cd2 +, 3.22, R4 for Hg2 +, Cd2 + & Pb2 +, 0.70, 0.20 & 0.30 μM) and the receptors R2, R5 &R6 are sensitive towards Cu2 + ions with the μM detection (3.34, 0.90 & 1.20 μM) in an aqueous medium among all other tested cations. The receptor R4 shows a multi-color response towards Hg2 +, Cu2 +, Cd2 + and Pb2 + ions. The recognition mechanism, stoichiometric binding ratio and detection limit (DL) have been examined by UV-Visible spectroscopic titration experiments and Benesi-Hildebrand (B-H) plot, receptor R1-R6 sowed 1:1 binding ratio with good binding constant range of 103 to 105 M- 1 with Hg2 +, Cu2 +, Cd2 + and Pb2 + ions metal ions.

  20. Do the levels of selected metals differ significantly between the roots of carious and non-carious teeth?

    Energy Technology Data Exchange (ETDEWEB)

    Malara, Piotr [Silesian Medical University, Department of Maxillofacial Surgery 20/24 Francuska Street, 40-027 Katowice (Poland)]. E-mail: malara@netinfo.pl; Kwapulinski, Jerzy [Silesian Medical University, Department of Toxicology 4 Jagiellonska Street, 41-200 Sosnowiec (Poland); Malara, Beata [Silesian Medical University, Department of Environmental Medicine and Epidemiology 19 Jordana Street, 41-808 Zabrze (Poland)

    2006-10-01

    Since the metals deposited in teeth during formation and mineralization processes are to a large extent retained, human teeth receive a considerable attention as the indicators of the heavy metal exposure. The use of permanent teeth is limited because the extraction of healthy permanent teeth just for this purpose is hardly acceptable. As the issue of the loss of elements from a carious lesion in the coronal part of a tooth remains controversial, the valuable material could only be the root of carious and fractured permanent teeth. However, to ensure the validity of the results, it should be ascertained that the levels of certain toxic and essential elements do not differ significantly between the roots of non-carious and carious teeth, and therefore this is the aim of this project. The levels of cadmium, chromium, copper, iron, manganese, lead, zinc, potassium, sodium, calcium and magnesium were determined in the roots of 344 permanent teeth (189 carious and 155 caries-free teeth) from the residents of Ruda Slaska, Poland, aged 18 to 34. No statistically significant difference between the concentration of these metals in the roots of non-carious and carious teeth was found. This finding applies to both the general population and after the grouping by donor's gender and tooth type. The concentration of lead, iron, calcium and manganese in the roots of non-carious and carious teeth exhibited dependence upon tooth type, as well as the concentration of potassium in the roots of carious teeth. Since the mineral composition of the roots of permanent teeth is similar for the non-carious, as well as the carious teeth, they can be indiscriminately selected for the tests required by a research project, as they will produce the comparable results. However, in the case of lead, iron, calcium, potassium and manganese, the comparison should be made after grouping by tooth type.

  1. New insights into selective heterogeneous nucleation of metal nanoparticles on oxides by microwave-assisted reduction: rapid synthesis of high-activity supported catalysts.

    Science.gov (United States)

    Anumol, Erumpukuthickal Ashok; Kundu, Paromita; Deshpande, Parag Arvind; Madras, Giridhar; Ravishankar, Narayanan

    2011-10-25

    Microwave-based methods are widely employed to synthesize metal nanoparticles on various substrates. However, the detailed mechanism of formation of such hybrids has not been addressed. In this paper, we describe the thermodynamic and kinetic aspects of reduction of metal salts by ethylene glycol under microwave heating conditions. On the basis of this analysis, we identify the temperatures above which the reduction of the metal salt is thermodynamically favorable and temperatures above which the rates of homogeneous nucleation of the metal and the heterogeneous nucleation of the metal on supports are favored. We delineate different conditions which favor the heterogeneous nucleation of the metal on the supports over homogeneous nucleation in the solvent medium based on the dielectric loss parameters of the solvent and the support and the metal/solvent and metal/support interfacial energies. Contrary to current understanding, we show that metal particles can be selectively formed on the substrate even under situations where the temperature of the substrate is lower than that of the surrounding medium. The catalytic activity of the Pt/CeO(2) and Pt/TiO(2) hybrids synthesized by this method for H(2) combustion reaction shows that complete conversion is achieved at temperatures as low as 100 °C with Pt-CeO(2) catalyst and at 50 °C with Pt-TiO(2) catalyst. Our method thus opens up possibilities for rational synthesis of high-activity supported catalysts using a fast microwave-based reduction method.

  2. The heavy metal contents of some selected medicinal plants sampled from different geographical locations

    Directory of Open Access Journals (Sweden)

    Kofi Annan

    2013-01-01

    Full Text Available Background: The levels of 5 minerals namely; lead, arsenic, mercury, cadmium, and aluminum were assessed in 10 medicinal plants sampled from 5 different geographical locations to determine the effect of location on the plants′ mineral content. Materials and Methods: Atomic absorption spectrophotometry (wet digestion was used for the analyzes, and content of the minerals per sample was expressed as μg/g. The levels of minerals were compared to their limit specification for herbs and daily total intake of these minerals. A two-way analysis of variance, which tends to look at the effect of the location and the medicinal plant itself on the plants mineral content, was used in the statistical analysis. Results: Lead (Pb was present in all plant species examined, except Ocimum gratissimum. One plant exceeded the maximum safety limit for lead. Cadmium was also detected in some of the medicinal plant species (44% whilst majority were below the detection limit (0.002 representing 56%. 40% of the plant species exceeded the limit for cadmium. Mercury and arsenic in all the plant species were below the detection limit (0.001. Significant variation existed in mineral content for the various locations ( P ≤ 0.05. Conclusion: The findings generally suggest the variation in mineral levels for the various locations. Thus, our study has shown that same species of medicinal plants, growing in different environments, accumulates different levels of heavy metals.

  3. Selective adsorption of thiophene and 1-benzothiophene on metal-ion-exchanged zeolites in organic medium.

    Science.gov (United States)

    Xue, Mei; Chitrakar, Ramesh; Sakane, Kohji; Hirotsu, Takahiro; Ooi, Kenta; Yoshimura, Yuji; Feng, Qi; Sumida, Naoto

    2005-05-15

    Adsorption of the organic sulfur compounds thiophene (TP) and 1-benzothiophene (1-BTP) in an organic model solution of hydrodesulfurizated gasoline (heptane with 1 wt% toluene and 0.156 mM (5 ppmw as sulfur) TP or 1-BTP) was studied by a batch method at 80 degrees C using metal-ion-exchanged Y-zeolites. Although NaY-zeolite or its acid-treated material rarely adsorbed the organic sulfur compounds, NaY-zeolites exchanged with Ag+, Cu2+, and Ce3+ ions and NH(4)Y-zeolites exchanged with Ce3+ ions showed markedly high adsorptive capacities for TP and 1-BTP. The sulfur uptake increased in the order CuY-zeolite(Na)

  4. Laser-beam modulation to improve efficiency of selecting laser melting for metal powders

    Science.gov (United States)

    Okunkova, A.; Peretyagin, P.; Vladimirov, Yuri; Volosova, M.; Torrecillas, R.; Fedorov, S. V.

    2014-05-01

    Nowadays additive manufacturing becomes more and more popular. It depends on the results of last achievements in developing of the new constructions for modern machine tools. One of the most developed AM technology is SLM or SLS. About twenty years ago the technology of rapid prototyping started to grow up from building prototypes and developed to real functional item production. Especially this becomes more important in producing medical implants in the full accordance with individual digital 3D-model from metallic powder as Ti6Al4V or CoCr. The additive technology gives the possibility to reduce additional steps in implants production process as work preparation process, forwarding a work piece from one shop to another one, post treatment etc. This approach is very topical to production of tooth, knee and coxal implants. This idea is realized in the commercial SLM machines as EOS M280, SLM Solutions 125HL (Germany), Phenix systems PXS/PXM Dental (France) (fig. 1).

  5. Decision Analysis Science Modeling for Application and Fielding Selection Applied to Metal Decontamination Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Lagos, L.E.; Ebadian, M.A.

    1998-01-01

    During the decontamination and decommissioning (D and D) activities being conducted by the U.S. Department of Energy (DOE), approximately 550,000 metric tons of contaminated metal will be generated by the disposition of contaminated buildings. The majority of the structural steel is considered to be radiologically contaminated. The D and D activities require the treatment of the structural steel to reduce occupational and environmental radiological exposures during dismantlement. Treatment technologies may also be required for possible recycling. Many proven commercial treatment technologies are available. These treatment processes vary in aggressiveness, safety requirements, secondary waste generation, necessary capital, and operation and maintenance costs. Choosing the appropriate technology to meet the decontamination objectives for structural steel is a difficult process. A single information source comparing innovative and nuclear and non-nuclear technologies in the areas of safety, cost and effectiveness is not currently commercially available to perform a detailed analysis. This study presents comparable data related to operation and maintenance, cost, and health and safely aspects of three readily available technologies and one innovative technology for nuclear decontamination. The technologies include Advance Recyclable Media System (ARMS{trademark}), NELCO Porta Shot Blast{trademark} (JHJ-2000), Pegasus Coating Removal System 7 (PCRS-7) and the innovative laser ablation technology called the Yag Eraser{trademark}.

  6. Electrosprayed Metal Oxide Semiconductor Films for Sensitive and Selective Detection of Hydrogen Sulfide

    Science.gov (United States)

    Ghimbeu, Camelia Matei; Lumbreras, Martine; Schoonman, Joop; Siadat, Maryam

    2009-01-01

    Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO2), tungsten oxide (WO3) and indium oxide (In2O3) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows porous homogeneous films comprising uniformly distributed aggregates of nano particles. The X-ray diffraction technique (XRD) proves the formation of crystalline phases with no impurities. Besides, the Raman cartographies provided information about the structural homogeneity. Some of the films are highly sensitive to low concentrations of H2S (10 ppm) at low operating temperatures (100 and 200 °C) and the best response in terms of Rair/Rgas is given by Cu-SnO2 films (2500) followed by WO3 (1200) and In2O3 (75). Moreover, all the films exhibit no cross-sensitivity to other reducing (SO2) or oxidizing (NO2) gases. PMID:22291557

  7. Influence of selected heavy metals (As, Cd, Cr, Cu on nematode communities in experimental soil microcosm

    Directory of Open Access Journals (Sweden)

    Šalamún P.

    2015-12-01

    Full Text Available In this study, the effects of arsenic, cadmium, copper and chromium treatments were examined on a nematode community structure and proportion of functional groups in the microcosm for 30 days. The toxic effects on the nematode community did not correspond with metals mobility (EDTA extraction in soil as it was expected. The most toxic element with a significant degradation of community structure was chromium (low mobile, which negatively affected almost all observed ecological parameters (abundance, diversity and ecological indices. On the other hand, cadmium and arsenic influence was negligible even in the plots treated with the highest concentrations and the communities resembled to the control samples. Copper showed a stimulative effect on the community under low concentration (40 mg.kg-1, while under higher concentrations the stimulation was replaced by stress responses. The widely used ecological indices, such as the Maturity Index 2-5, Structure Index, and Shannon-Weaver Index and c-p groups showed the best bioindication potential among nematode parameters.

  8. Effects of heavy metals and arbuscular mycorrhiza on the leaf proteome of a selected poplar clone: a time course analysis.

    Directory of Open Access Journals (Sweden)

    Guido Lingua

    Full Text Available Arbuscular mycorrhizal (AM fungi establish a mutualistic symbiosis with the roots of most plant species. While receiving photosynthates, they improve the mineral nutrition of the plant and can also increase its tolerance towards some pollutants, like heavy metals. Although the fungal symbionts exclusively colonize the plant roots, some plant responses can be systemic. Therefore, in this work a clone of Populus alba L., previously selected for its tolerance to copper and zinc, was used to investigate the effects of the symbiosis with the AM fungus Glomus intraradices on the leaf protein expression. Poplar leaf samples were collected from plants maintained in a glasshouse on polluted (copper and zinc contaminated or unpolluted soil, after four, six and sixteen months of growth. For each harvest, about 450 proteins were reproducibly separated on 2DE maps. At the first harvest the most relevant effect on protein modulation was exerted by the AM fungi, at the second one by the metals, and at the last one by both treatments. This work demonstrates how importantly the time of sampling affects the proteome responses in perennial plants. In addition, it underlines the ability of a proteomic approach, targeted on protein identification, to depict changes in a specific pattern of protein expression, while being still far from elucidating the biological function of each protein.

  9. Effects of Heavy Metals and Arbuscular Mycorrhiza on the Leaf Proteome of a Selected Poplar Clone: A Time Course Analysis

    Science.gov (United States)

    Lingua, Guido; Bona, Elisa; Todeschini, Valeria; Cattaneo, Chiara; Marsano, Francesco; Berta, Graziella; Cavaletto, Maria

    2012-01-01

    Arbuscular mycorrhizal (AM) fungi establish a mutualistic symbiosis with the roots of most plant species. While receiving photosynthates, they improve the mineral nutrition of the plant and can also increase its tolerance towards some pollutants, like heavy metals. Although the fungal symbionts exclusively colonize the plant roots, some plant responses can be systemic. Therefore, in this work a clone of Populus alba L., previously selected for its tolerance to copper and zinc, was used to investigate the effects of the symbiosis with the AM fungus Glomus intraradices on the leaf protein expression. Poplar leaf samples were collected from plants maintained in a glasshouse on polluted (copper and zinc contaminated) or unpolluted soil, after four, six and sixteen months of growth. For each harvest, about 450 proteins were reproducibly separated on 2DE maps. At the first harvest the most relevant effect on protein modulation was exerted by the AM fungi, at the second one by the metals, and at the last one by both treatments. This work demonstrates how importantly the time of sampling affects the proteome responses in perennial plants. In addition, it underlines the ability of a proteomic approach, targeted on protein identification, to depict changes in a specific pattern of protein expression, while being still far from elucidating the biological function of each protein. PMID:22761694

  10. A thiourea-functionalized metal-organic macrocycle for the catalysis of Michael additions and prominent size-selective effect.

    Science.gov (United States)

    Yang, Lu; Zhao, Liang; Zhou, Zhen; He, Cheng; Sun, Hui; Duan, Chunying

    2017-03-21

    A discrete tetranuclear thiourea-based metal-organic macrocycle (MOM) with a large size was constructed by a well-designed organic ligand and nickel(ii) ions via self-assembly. Incorporating thiourea groups as hydrogen-bond donors into a metal-organic complex system leads to a new approach for synthesizing functionalized heterogeneous catalysts, as this not only introduces coordination sites serving as chelators, but also overcomes the issues of self-association via intermolecular H-bonding, often occurring in homogeneous systems. The packing structure of this material formed a confined environment suitable for the access of substrate molecules dragged by the strong hydrogen-bond interactions from the thiourea groups, thus achieving a high catalytic performance in Michael additions of nitrostyrenes to nitroalkanes, with remarkable yields and size-selectivity in heterogeneous phase. Moreover, a comparison of the IR spectrum of Ni-SPT with the spectra of dimethyl malonate- and β-nitrostyrene-impregnated Ni-SPT indicated that both substrate molecules, β-nitrostyrene and dimethyl malonate, were able to access the cavity of the trimeric subunit.

  11. Porphyrins as Templates for Site-Selective Atomic Layer Deposition: Vapor Metalation and in Situ Monitoring of Island Growth.

    Science.gov (United States)

    Avila, Jason R; Emery, Jonathan D; Pellin, Michael J; Martinson, Alex B F; Farha, Omar K; Hupp, Joseph T

    2016-08-10

    Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analytical fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials.

  12. Selective degradation of organic dyes by a resin modified Fe-based metal-organic framework under visible light irradiation

    Science.gov (United States)

    Araya, Tirusew; Chen, Chun-cheng; Jia, Man-ke; Johnson, David; Li, Ruiping; Huang, Ying-ping

    2017-02-01

    Metal organic frameworks (MOFs), a new class of porous crystalline materials have attracted attention because of potential applications in environmental remediation. In this work, an Fe-based MOF, FeBTC (BTC = 1,3,5-tricarboxylic acid), was successfully modified with Amberlite IRA-200 resin to yield a novel heterogeneous photocatalyst, A@FeBTC. The modification resulted in higher photocatalytic activity than FeBTC under the same conditions. After 60 min of visible light illumination (λ ≥ 420 nm) 99% of rhodamine B was degraded. The modification lowers the zeta potential, enhancing charge-based selective adsorption and subsequent photocatalytic degradation of cationic dye pollutants. The composite also improved catalyst stability and recyclability by significantly reducing loss of iron leaching. Photoluminescence studies show that introduction of the resin reduces the recombination rate of photogenerated charge carriers thereby improving the photocatalytic activity of the composite. Finally, a plausible photocatalytic reaction mechanism is proposed.

  13. A porous Cd(II) metal-organic framework with high adsorption selectivity for CO2 over CH4

    Science.gov (United States)

    Zhu, Chunlan

    2017-05-01

    Metal-organic frameworks (MOFs) have attracted a lot of attention in recent decades. We applied a semi-rigid four-carboxylic acid linker to assemble with Cd(II) ions to generate a novel microporous Cd(II) MOF material. Single crystal X-ray diffraction study reveals the different two dimension (2D) layers can be further packed together with an AB fashion by hydrogen bonds (O4sbnd H4⋯O7 = 1.863 Å) to construct a three dimension (3D) supermolecular architecture. The resulting sample can be synthesized under solvothermal reactions successfully, which exhibits high selectivity adsorption of CO2 over CH4 at room temperature. In addition, the obtained sample was characterized by thermal gravimetric analyses (TGA), Fourier-transform infrared spectra (FT-IR), elemental analysis (CHN) and powder X-ray diffraction (PXRD).

  14. Predictive framework for shape-selective separations in three-dimensional zeolites and metal-organic frameworks.

    Science.gov (United States)

    First, Eric L; Gounaris, Chrysanthos E; Floudas, Christodoulos A

    2013-05-07

    With the growing number of zeolites and metal-organic frameworks (MOFs) available, computational methods are needed to screen databases of structures to identify those most suitable for applications of interest. We have developed novel methods based on mathematical optimization to predict the shape selectivity of zeolites and MOFs in three dimensions by considering the energy costs of transport through possible pathways. Our approach is applied to databases of over 1800 microporous materials including zeolites, MOFs, zeolitic imidazolate frameworks, and hypothetical MOFs. New materials are identified for applications in gas separations (CO2/N2, CO2/CH4, and CO2/H2), air separation (O2/N2), and chemicals (propane/propylene, ethane/ethylene, styrene/ethylbenzene, and xylenes).

  15. Construction of flexible metal-organic framework (MOF) papers through MOF growth on filter paper and their selective dye capture.

    Science.gov (United States)

    Park, Jeehyun; Oh, Moonhyun

    2017-09-14

    The conjugation of metal-organic frameworks (MOFs) with other materials is an excellent strategy for the production of advanced materials having desired properties and so appropriate applicability. In particular, the integration of MOFs with a flexible paper is expected to form valuable materials in separation technology. Here we report a simple method for the generation of MOF papers through the compact and uniform growth of MOF nanoparticles on the cellulose surface of a carboxymethylated filter paper. The resulting MOF papers show a selective capture ability for negatively charged organic dyes and they can be used for dye separation through simple filtration of a dye solution on the MOF papers. In addition, MOF papers can be reused after a simple washing process without losing their effective dye capture ability.

  16. Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation.

    Science.gov (United States)

    Biswal, Bishnu P; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K

    2015-04-28

    Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

  17. A Terbium Metal-Organic Framework for Highly Selective and Sensitive Luminescence Sensing of Hg(2+) Ions in Aqueous Solution.

    Science.gov (United States)

    Xia, Tifeng; Song, Tao; Zhang, Gege; Cui, Yuanjing; Yang, Yu; Wang, Zhiyu; Qian, Guodong

    2016-12-19

    A series of isomorphic lanthanide metal-organic frameworks (MOFs) Ln(TATAB)⋅(DMF)4 (H2 O)(MeOH)0.5 (LnTATAB, Ln=Eu, Tb, Sm, Dy, Gd; H3 TATAB=4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoic acid) have been solvothermally synthesized and structurally characterized. Among these MOFs, TbTATAB exhibits good water stability and a high fluorescence quantum yield. Because mercury ions (Hg(2+) ) have a high affinity to nitrogen atoms, and the space between multiple nitrogen atoms from triazine and imino groups is suitable for interacting with Hg(2+) ions, TbTATAB shows highly selective and sensitive detection of Hg(2+) in aqueous solution with a detection limit of 4.4 nm. Furthermore, it was successfully applied to detect Hg(2+) ions in natural water samples. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A STUDY ON THE CONCENTRATION OF HEAVY METALS IN THE DRINKING WATER OF SELECTED AREAS OF IMPHAL EAST DISTRICT, MANIPUR (INDIA

    Directory of Open Access Journals (Sweden)

    Joychandra

    2014-06-01

    Full Text Available The present study attempts to evaluate the quality of the drinking water (tap particularly heavy metal concentrations (Fe, Zn, Pb, Cu and Cd in selected areas of Imphal east district, Manipur. Findings were compared with the Indian Standard (ISI and Indian Council of Medical Research (ICMR for drinking water specification. Concentrations of metals such as iron, cadmium and lead are alarming. They crossed the maximum permissible limit for drinking water standards set by ISI and ICMR

  19. Effects of Lewis acidity of metal oxide promoters on the activity and selectivity of Co-based Fischer–Tropsch synthesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gregory R.; Bell, Alexis T. (LBNL); (UCB)

    2016-06-17

    Metal oxides of Ce, Gd, La, Mn, and Zr were investigated as promoters for improving the activity and selectivity of Co-based FTS catalysts. The extent to which these promoters decrease the selectivity toward CH4 and increase the selectivity toward C5+ hydrocarbons was found to depend on both the loading and the composition of the oxide promoter. Elemental mapping by STEM–EDS revealed that the propensity for a given metal oxide to associate with Co affects the sensitivity of the product distribution to changes in promoter loading. For all promoters, a sufficiently high loading resulted in the product distributions becoming insensitive to further increases in promoter loading, very likely due to the formation of a half monolayer of promoter oxide over the Co surface. Simulations suggest that the fraction of Co active sites that are adjacent to the promoter moieties approaches unity at this degree of coverage. The oxidation state of the promoter metal cation under reaction conditions, determined by in situ XANES measurements, was used to calculate relative Lewis acidity of the promoter metal cation. A strong positive correlation was found between the C5+ product selectivity and the Lewis acidity of the promoter metal cations, suggesting that the promotional effects are a consequence of Lewis acid–base interactions between the reaction intermediates and the promoter metal cations. Rate data obtained at different pressures were used to estimate the apparent rate coefficient and the CO adsorption constant appearing in the Langmuir–Hinshelwood expression that describes the CO consumption kinetics for both unpromoted and the metal oxide-promoted catalysts. Both parameters exhibited positive correlations with the promoter Lewis acidity. In conclusion, these results are consistent with the hypothesis that the metal cations of the promoter act as Lewis acids that interact with the O atom of adsorbed CO to facilitate CO adsorption and

  20. Facile Preparation of Core-Shell Magnetic Metal-Organic Framework Nanoparticles for the Selective Capture of Phosphopeptides.

    Science.gov (United States)

    Chen, Yajing; Xiong, Zhichao; Peng, Li; Gan, Yangyang; Zhao, Yiman; Shen, Jie; Qian, Junhong; Zhang, Lingyi; Zhang, Weibing

    2015-08-05

    In regard to the phosphoproteome, highly specific and efficient capture of heteroideous kinds of phosphopeptides from intricate biological sample attaches great significance to comprehensive and in-depth phosphorylated proteomics research. However, until now, it has been a challenge. In this study, a new-fashioned porous immobilized metal ion affinity chromatography (IMAC) material was designed and fabricated to promote the selectivity and detection limit for phosphopeptides by covering a metal-organic frameworks (MOFs) shell onto Fe3O4 nanoparticles, taking advantage of layer-by-layer method (the synthesized nanoparticle denoted as Fe3O4@MIL-100 (Fe)). The thick layer renders the nanoparticles with perfect hydrophilic character, super large surface area, large immobilization of the Fe(3+) ions and the special porous structure. Specifically, the as-synthesized MOF-decorated magnetic nanoparticles own an ultra large surface area which is up to 168.66 m(2) g(-1) as well as two appropriate pore sizes of 1.93 and 3.91 nm with a narrow grain-size distribution and rapid separation under the magnetic circumstance. The unique features vested the synthesized nanoparticles an excellent ability for phosphopeptides enrichment with high selectivity for β-casein (molar ratio of β-casein/BSA, 1:500), large enrichment capacity (60 mg g(-1)), low detection limit (0.5 fmol), excellent phosphopeptides recovery (above 84.47%), fine size-exclusion of high molecular weight proteins, good reusability, and desirable batch-to-batch repeatability. Furthermore, encouraged by the experimental results, we successfully performed the as-prepared porous IMAC nanoparticle in the specific capture of phosphopeptides from the human serum (both the healthy and unhealthy) and nonfat milk, which proves itself to be a good candidate for the enrichment and detection of the low-abundant phosphopeptides from complicated biological samples.

  1. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Directory of Open Access Journals (Sweden)

    Elena García-Giménez

    2012-01-01

    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  2. Selecting the suitable dopants: electronic structures of transition metal and rare earth doped thermoelectric sodium cobaltate

    CERN Document Server

    Assadi, M H N; Yu, A B

    2012-01-01

    Engineered Na0.75CoO2 is considered a prime candidate to achieve high efficiency thermoelectric systems to regenerate electricity from waste heat. In this work, three elements with outmost electronic configurations, (1) an open d shell (Ni), (2) a closed d shell (Zn), and (3) an half fill f shell (Eu) with a maximum unpaired electrons, were selected to outline the dopants' effects on electronic and crystallographic structures of Na0.75CoO2. Systematic ab initio density functional calculations showed that the formation energy of these dopants was found to be lowest when residing on sodium layer and ranked as -1.1 eV, 0.44 eV and 3.44 eV for Eu, Ni and Zn respectively. Furthermore Ni was also found to be stable when substituting Co ion. As these results show great harmony with existing experimental data, they provide new insights into the fundamental principle of dopant selection for manipulating the physical properties in the development of high performance sodium cobaltate based thermoelectric materials.

  3. Zirconium-based metal organic frameworks: Highly selective adsorbents for removal of phosphate from water and urine

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Kun-Yi Andrew, E-mail: linky@nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung, Taiwan (China); Chen, Shen-Yi [Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung, Taiwan (China); Jochems, Andrew P. [New Mexico Bureau of Geology & Mineral Resources and New Mexico Institute of Mining & Technology, Socorro, NM (United States)

    2015-06-15

    Phosphate is one of the most concerning compounds in wastewater streams and a main nutrient that causes eutrophication. To eliminate the phosphate pollution, Metal Organic Frameworks (MOFs) are proposed in this study as adsorbents to remove phosphate from water. The zirconium-based MOF, UiO-66, was selected as representative MOF given its exceptional stability in water. To investigate the effect of an amine functional group, UiO-66-NH2 was also prepared using an amine-substituted ligand. The adsorption kinetics and isotherm reveal that UiO-66-NH2 exhibited higher adsorption capacities than UiO-66 possibly due to the amine group. However, the interaction between phosphate and zirconium sites of UiO MOFs might be the primary factor accounting for the phosphate adsorption to UiO MOFs. UiO MOFs also exhibited a high selectivity towards phosphate over other anions such as bromate, nitrite and nitrate. Furthermore, UiO MOFs were found to adsorb phosphate and to completely remove diluted phosphate in urine. We also found that UiO MOFs could be easily regenerated and re-used for phosphate adsorption. These findings suggest that UiO MOFs can be effective and selective adsorbents to remove phosphate from water as well as urine. - Highlights: • UiO-66 as the first type of MOFs was used to remove phosphate from water and urine. • The amine group in UiO MOFs was found to enhance the phosphate adsorption. • UiO-66 exhibited a high adsorption selectivity towards phosphate over other anions. • UiO-66 could be easily regenerated and re-used with 85% regeneration efficiency.

  4. Synthesis of nanoporous carbohydrate metal-organic framework and encapsulation of selected organic compounds

    Science.gov (United States)

    Al-Ghamdi, Saleh

    Cyclodextrin metal organic frameworks (CDMOFs) with different types of cyclodextrins (CDs) (i.e., Alpha, Beta and Gamma-CD) and coordination potassium ion sources (KOH) CDMOF-a and (C7H5KO2) CDMOF-b were synthesized and fully characterized. The physical and thermal properties of the successfully produced CDMOFs were evaluated using N2 gas sorption, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The N2 gas sorption isotherm revealed high uptake into the micropores (330 cm3.g -1 for Gamma-CDMOF-a) to macropore (125 cm3.g -1 for Gamma-CDMOF-b) structures with isotherm types I and II for Gamma-CDMOFs and Alpha-CDMOFs, respectively. The Langmuir specific surface area (SSA) of Gamma-CDMOF-a (1376 m2.g-1) was significantly higher than the SSA of Alpha-CDMOF-a (289 m2.g -1) and Beta-CDMOF-a (54 m2.g-1). The TGA of dehydrated CDMOF crystals showed the structures were thermally stable up to 300 °C. The XRD of the Gamma-CDMOFs and Alpha-CDMOFs showed a highly face-centered-cubic symmetrical structure. An Aldol condensation reaction occurred during the encapsulation of acetaldehyde, hexanal, trans-2-hexenal, and ethanol into Gamma-CDMOF-a, with a SSA of 1416 m2.g -1. However, Gamma-CDMOF-b with a SSA of 499 m2.g -1 was successfully used to encapsulate acetaldehyde. The maximum release of acetaldehyde from CDMOF-b was 53 mug of acetaldehyde per g of CDMOF, which is greater than previously reported acetaldehyde encapsulation on Beta-CD inclusion complexes.

  5. Stent selection in patients with myocardial infarction: drug eluting, biodegradable polymers or bare metal stents?

    Science.gov (United States)

    Mieres, Juan; Rodríguez, Alfredo E

    2012-08-01

    Percutaneous coronary intervention (PCI) has been increasingly used in the last years during interventional procedures in patients with acute coronary syndromes (ACS) including ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI). In patients with either STEMI, NSTEMI, high risk ACS with EKG changes or cardiac enzymes rises; PCI with bare metal stent (BMS) implantation has been associated with a significant improvement in clinical outcome. Therefore, BMS implantation during primary PCI in STEMI has become a standard of practice. With the introduction of drug eluting stents (DESs) in this decade, the use of these new devices instead of BMSs in patients with STEMI has emerged as a rational PCI alternative in this particular subgroup of patients. In spite of the unquestionable benefits of DESs in terms of reduction of restenosis and TVR, specific concerns have arisen with regard to their long-term safety. High incidence of very late stent thrombosis has been described with these devices, and special attention should be paid in patients with unstable coronary lesions, in which plaque composition and remodeling may play a main role in their safety and long-term outcome. Intraluminal thrombus caused by plaque rupture is the most frequent mechanism of STEMI, in which the necrotic core and thin fibrous cap play a major role. In this context, the use of first DESs designs may be futile or even unsafe because delayed healing may further contribute to plaque instability. Adjunctive invasive imaging tools can improve stent deployment and safety outcome in these lesions with intravascular findings of plaque instability. Recently, other players such as new dedicated antithrombotic BMS designs, including selfexpanding stents or drug-eluting coated balloons, are exploring their potential indications in patients with ACS and myocardial infarction. This paper reports and discusses new stent devices and adjunctive pharmacologic agents. It

  6. Universal approach for selective trace metal determinations via sequential injection-bead injection-lab-on-valve using renewable hydrophobic bead surfaces as reagent carriers

    DEFF Research Database (Denmark)

    Long, Xiangbao; Miró, Manuel; Hansen, Elo Harald

    2005-01-01

    A new concept is presented for selective and sensitive determination of trace metals via electrothermal atomic absorption spectrometry (ETAAS) based on the principle of bead injection (BI) with renewable reversed-phase surfaces in a sequential injection-lab-on-valve (SI-LOV) mode. The methodology...... involves the use of poly(styrene-divinylbenzene) beads containing pendant octadecyl moieties (C18-PS/DVB), which are preimpregnated with a selective organic metal chelating agent prior to the automatic manipulation of the beads in the microbore conduits of the LOV unit. By adapting this approach......, the immobilization of the most suitable chelating agent can be effected irrespective of the kinetics involved, optimal reaction conditions can be used for implementing the chelating reaction of the target metal analyte with the immobilized reagent, and an added degree of freedom is offered in selecting the most...

  7. The redshifted selected sample of long gamma-ray burst host galaxies: the complete metallicity measurements at $z \\leq 0.41$

    CERN Document Server

    Niino, Yuu; Hashimoto, Tetsuya; Hattori, Takashi; Ishikawa, Shoto; Kashikawa, Nobunari; Kosugi, George; Onoue, Masafusa; Toshikawa, Jun; Yabe, Kiyoto

    2016-01-01

    We present the complete list of host galaxy metallicities for all long GRBs whose redshifts were determined to be $\\leq 0.41$ before the end of March 2014, including newly obtained spectroscopic datasets of the host galaxies of GRB 060614, 090417B, and 130427A. We compare the metallicity distribution of the redshift selected complete sample to the model predictions, and constrain the relation between metallicity and GRB occurrence. We take account of spatial variation of metallicities among star forming regions within a galaxy. We found that the models, in which only low-metallicity stars produce GRBs with a sharp cutoff of GRB production efficiency around 12+log(O/H) $\\sim$ 8.2, can well reproduce the observed distribution, while the models with moderate (or no) metallicity dependence are not consitistent with the observations. This is the first fair estimate of the metallicity distribution of GRB host galaxies based on the redshift selected complete sample in the {\\it Swift} era. We also discuss possible sa...

  8. Total and Available Heavy Metal Concentrations and Assessment of Soil Pollution Indices in Selected Soils of Zanjan

    Directory of Open Access Journals (Sweden)

    M. Taheri

    2017-01-01

    content of soils were respect to control these indices. Geoaccumulation index of Zn, Cd and Pb, and availability ratios of Zn and Pb showed negative correlations with soil pH. Therefore, in some seasons of the year, their availabilities will increase in soil. Conclusion: The results showed that Cu content in soils were not in the critical limit but Cd, Pb and Zn content in soils were greater than standard levels and reclamation procedures for remedy of these soils must be done. The high values of the heavy metals in available fraction inthe soils increased the risk of bioaccumulation in microbial and biotic tissues. In areas where there are high content of available form of heavy metals in soils, it could be an index of new contamination in soils by heavy metals. According to geoaccumulation index of Cd, Zn and Pb, there are some contaminated points around waste depositition areas near Zanjan city. These points are in the direction that wind could effectively transport the particles of wastes to urban area. Enrichment factor (EF showed that at least there were a few points polluted by Cd, Zn and Cu, although EF values were generally low. The leaked wastes of Zinc and lead industries had been spread in deposited areas caused difficulties in determining background values for the selected metals.

  9. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application

    Science.gov (United States)

    Laakso, J. H.; Straayer, J. W.

    1974-01-01

    A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.

  10. Experimental Study of Residual Stresses in Metal Parts Obtained by Selective Laser Melting

    Science.gov (United States)

    Protasov, C. E.; Safronov, V. A.; Kotoban, D. V.; Gusarov, A. V.

    High local temperature gradients occur at additive manufacturing by selective laser melting of powder. This gives rise to undesirable residual stresses, deformations, and cracks. To understand how to control the formation of the residual stresses, a reliable method is necessary for measuring their distribution in the fabricated part. It is proposed to cut the part into thin plates and to reconstruct the residual stresses from the measured deformation of the plates. This method is tested on beams with square cross-section built from stainless steel. The beams were cut by electrical discharge machining and chemically etched. The obtained stress profile in vertical transversal direction slightly increases from the top to the bottom of the beam. This dependency is confirmed by numerical modeling. The measured stress profile agrees with the known results by other authors.

  11. Selective propagation and beam splitting of surface plasmons on metallic nanodisk chains.

    Science.gov (United States)

    Hu, Yuhui; Zhao, Di; Wang, Zhenghan; Chen, Fei; Xiong, Xiang; Peng, Ruwen; Wang, Mu

    2017-05-01

    Manipulating the propagation of surface plasmons (SPs) on a nanoscale is a fundamental issue of nanophotonics. By using focused electron beam, SPs can be excited with high spatial accuracy. Here we report on the propagation of SPs on a chain of gold nanodisks with cathodoluminescence (CL) spectroscopy. Experimental evidence for the propagation of SPs excited by the focused electron beam is demonstrated. The wavelength of the transmitted SPs depends on the geometrical parameters of the nanodisk chain. Furthermore, we design and fabricate a beam splitter, which selectively transmits SPs of certain wavelengths to a specific direction. By scanning the sample surface point by point and collecting the CL spectra, we obtain the spectral mapping and identify that the chain of the smaller nanodisks can efficiently transport SPs at shorter wavelengths. This Letter provides a unique approach to manipulate in-plane propagation of SPs.

  12. Variation of Fruit Characters among the Natural Population of Quercus liaotungensis Koidz and the Selection of Superior Types%辽东栎天然群体结实性状变异与优良类型选择

    Institute of Scientific and Technical Information of China (English)

    李忠红; 厉月桥; 任向阳; 李冬云; 杜建霞

    2012-01-01

    [目的]为探明北京西山山区辽东栎天然群体结实性状的自然变异,筛选出在果实丰产、优质等方面表现优良的类型.[方法]对12块标准地中134株辽东栎植株结实性状(果长、果宽、平均果径、果长/果宽、单果重等)进行了测定分析.[结果]辽东栎果实表型性状果长、果宽、平均果径、果长/果宽、单果重个体间变异幅度均高于个体内,差异达到了极显著差异(P<0.01);辽东栎天然群体被划分为散生小果型、散生中果型、散生大果型、簇生小果型、簇生中果型和簇生大果型6种类型;簇生中果型和簇生大果型植株单位面积结实量分别为32.86和34.65g/m2,显著高于其他类型(P<0.05),散生大果型和簇生大果型平均果径分别为16.37、15.56 cm,显著高于其他类型.[结论]辽东栎天然群体内果实表型性状存在着丰富变异,簇生中果型、散生大果型和簇生大果型可作为丰产、易收集优良种质进一步研究和利用.%[ Objective] To illustrate the variation law of fruit characters among the natural population of Quercus liaotungensis Koidz in western mountainous area of Beijing, and select superior type in terms of yield and quality. [Method] Fruiting characters (fruits length, width, average diameter, ratio of length to width, and unit weight) of 134 trees in 12 standard plots of Quercus liaotungensis Koidz were determined and analyzed. [ Result] The range of variation among the individuals were higher than within the individuals with respect to the length, width, av-erage diameter, ratio of length to width, and unit weight. The natural population of Quercus liaotungensis Koidz can be divided into six types, including small scattered fruit, medium scattered fruit, big scattered fruit, small clustered fruit, medium clustered fruit and big clustered fruit. The fruit weight of per unit area of medium clustered type and big clustered type were 32,86 g/m and 34.65 g

  13. ADSORPTION SELECTIVITY FOR Cu2+,Ni2+,Co2+IONS USING CROSSLINKING CHITOSAN RESINS IMPRINTED BY METAL IONS

    Institute of Scientific and Technical Information of China (English)

    HUANGWenqiang; HANLijun; 等

    1999-01-01

    Metal ion-imprintedly crosslinked chitosan resin 1 and resin 2 were prepared by the use of Cu2+ and Ni2+ as template ions and glutaraldehyde as crosslinking agent,respectively,Through investigation on the adsorption capacties and binding constants for Cu2+,Ni2+ and Co2+ ions on chitosan resins,resin 1 and resin 2 exhibit the adsorption selectivity for the mixture solution of 1L1 Cu2+ and Ni2+ ions.The adsorption selectivity of metal ion-imprinted resins for their template ions in much higher than that of uncrosslinked chitosan resin.

  14. Site-selective functionalization of periodic mesoporous organosilica (PMO) with macrocyclic host for specific and reversible recognition of heavy metal.

    Science.gov (United States)

    Ye, Gang; Leng, Yuxiao; Bai, Feifei; Wei, Jichao; Wang, Jianchen; Chen, Jing

    2013-07-01

    A novel kind of macrocyclic-host-functionalized periodic mesoporous organosilica (PMO) with excellent and reversible recognition of Pb(II) was developed. The macrocyclic host molecule cis-dicyclohexano[18]crown-6, with strong affinity to Pb(II), was carefully modified as a bridged precursor to build the PMO material. To break down the limit of the functionalization degree for PMOs incorporated with large-sized moieties, a site-selective post-functionalization method was proposed to further decorate the external surface of the PMO material. The selective recognition ability of the upgraded PMO material towards Pb(II) was remarkably enhanced without destroying the mesoporous ordering. Solid-state (13)C and (29)Si NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), XRD, TEM, and nitrogen adsorption-desorption isotherm measurements were utilized for a full characterization of the structure, micromorphology, and surface properties. Reversible binding of Pb(II) was realized in the binding-elution cycle experiments. The mechanism of the supramolecular interaction between the macrocyclic host and metal ion was discussed. The synthetic strategy can be considered a general way to optimize the properties of PMOs as binding materials for practical use while preserving the mesostructure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Influence of the selective EDTA derivative phenyldiaminetetraacetic acid on the speciation and extraction of heavy metals from a contaminated soil.

    Science.gov (United States)

    Zhang, Tao; Wei, Hang; Yang, Xiu-Hong; Xia, Bing; Liu, Jun-Min; Su, Cheng-Yong; Qiu, Rong-Liang

    2014-08-01

    The development of more selective chelators for the washing of heavy metal contaminated soil is desirable in order to avoid excessive dissolution of soil minerals. Speciation and mobility of Cu, Zn, Pb, and Ni in a contaminated soil washed with phenyldiaminetetraacetic acid (PDTA), a derivative of EDTA, were investigated by batch leaching test using a range of soil washing conditions followed by sequential extraction. With appropriate washing conditions, PDTA significantly enhanced extraction of Cu from the contaminated soil. The primary mechanisms of Cu extraction by PDTA were complexation-promoted dissolution of soil Cu and increased dissolution of soil organic matter (SOM). PDTA showed high selectivity for Cu(II) over soil component cations (Ca(II), Mg(II), Fe(III), Mn(II), Al(III)), especially at lower liquid-to-soil ratios under PDTA deficiency, thus avoiding unwanted dissolution of soil minerals during the soil washing process which can degrade soil structure and interfere with future land use. PDTA-enhanced soil washing increased the exchangeable fractions of Cu, Zn, and Pb and decreased their residual fractions, compared to their levels in unwashed soil.

  16. Green and selective polycondensation methods toward linear sorbitol-based polyesters: enzymatic versus organic and metal-based catalysis.

    Science.gov (United States)

    Gustini, Liliana; Lavilla, Cristina; Janssen, William W T J; Martínez de Ilarduya, Antxon; Muñoz-Guerra, Sebastián; Koning, Cor E

    2016-08-23

    Renewable polyesters derived from a sugar alcohol (i.e., sorbitol) were synthesized by solvent-free polycondensation. The aim was to prepare linear polyesters with pendant hydroxyl groups along the polymer backbone. The performance of the sustainable biocatalyst SPRIN liposorb CALB [an immobilized form of Candida antarctica lipase B (CALB); SPRIN technologies] and the organo-base catalyst 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) were compared with two metal-based catalysts: dibutyl tin oxide (DBTO) and scandium trifluoromethanesulfonate [also known as scandium triflate, Sc(OTf)3 ]. For the four catalytic systems, the efficiency and selectivity for the incorporation of sorbitol were studied, mainly using (13) C and (31) P NMR spectroscopies, whereas side reactions, such as ether formation and dehydration of sorbitol, were evaluated using MALDI-TOF-MS. Especially the biocatalyst SPRIN liposorb CALB succeeded in incorporating sorbitol in a selective way without side reactions, leading to close-to-linear polyesters. By using a renewable hydroxyl-reactive curing agent based on l-lysine, transparent and glossy poly(ester urethane) networks were successfully synthesized offering a tangible example of bio-based coatings.

  17. Distribution, speciation, and risk assessment of selected metals in the gold and iron mine soils of the catchment area of Miyun Reservoir, Beijing, China.

    Science.gov (United States)

    Huang, Xingxing; Zhu, Yi; Ji, Hongbing

    2013-10-01

    In order to investigate the metal distribution, speciation, correlation and origin, risk assessment, 86 surface soil samples from the catchment area around the Miyun Reservoir, Beijing, including samples from gold and iron mine areas, were monitored for fractions of heavy metal and total contents. Most of the metal concentrations in the gold and iron mine soil samples exceeded the metal background levels in Beijing. The contents of most elements in the gold mine tailings were noticeably higher than those in the iron mine tailings. Geochemical speciation data of the metals showed that the residual fraction dominated most of the heavy metals in both mines. In both mine areas, Mn had the greatest the acid-soluble fraction (F1) per portion. The high secondary-phase fraction portion of Cd in gold mine samples indicated that there was a direct potential hazard to organisms in the tested areas. Multivariate analysis coupled with the contents of selected metals, showed that Hg, Pb, Cr, and Ni in gold mine areas represented anthropogenic sources; Cd, Pb, and Cr in iron mine areas represented industrial sources. There was moderate to high contamination of a few metals in the gold and iron soil samples, the contamination levels were relatively higher in gold mine than in iron mine soils.

  18. Inhibitory projections from the ventral nucleus of the lateral lemniscus and superior paraolivary nucleus create directional selectivity of frequency modulations in the inferior colliculus: A comparison of bats with other mammals

    OpenAIRE

    Pollak, George D.; Gittelman, Joshua X; Li, Na; Xie, Ruili

    2010-01-01

    This review considers four auditory brainstem nuclear groups and shows how studies of both bats and other mammals have provided insights into their response properties and the impact of their convergence in the inferior colliculus (IC). The four groups are octopus cells in the cochlear nucleus, their connections with the ventral nucleus of the lateral lemniscus (VNLL) and the superior paraolivary nucleus (SPON), and the connections of the VNLL and SPON with the IC. The theme is that the respo...

  19. Fluorescent metal-organic framework MIL-53(Al) for highly selective and sensitive detection of Fe3+ in aqueous solution.

    Science.gov (United States)

    Yang, Cheng-Xiong; Ren, Hu-Bo; Yan, Xiu-Ping

    2013-08-06

    Fluorescent metal-organic frameworks (MOFs) have received great attention in sensing application. Here, we report the exploration of fluorescent MIL-53(Al) for highly selective and sensitive detection of Fe(3+) in aqueous solution. The cation exchange between Fe(3+) and the framework metal ion Al(3+) in MIL-53(Al) led to the quenching of the fluorescence of MIL-53(Al) due to the transformation of strong-fluorescent MIL-53(Al) to weak-fluorescent MIL-53(Fe), allowing highly selective and sensitive detection of Fe(3+) in aqueous solution with a linear range of 3-200 μM and a detection limit of 0.9 μM. No interferences from 0.8 M Na(+); 0.35 M K(+); 11 mM Cu(2+); 10 mM Ni(2+); 6 mM Ca(2+), Pb(2+), and Al(3+); 5.5 mM Mn(2+); 5 mM Co(2+) and Cr(3+); 4 mM Hg(2+), Cd(2+), Zn(2+), and Mg(2+); 3 mM Fe(2+); 0.8 M Cl(-); 60 mM NO2(-) and NO3(-); 10 mM HPO4(2-), H2PO4(-), SO3(2-), SO4(2-), and HCOO(-); 8 mM CO3(2-), HCO3(-), and C2O4(2-); and 5 mM CH3COO(-) were found for the detection of 150 μM Fe(3+). The possible mechanism for the quenching effect of Fe(3+) on the fluorescence of MIL-53(Al) was elucidated by inductively coupled plasma-mass spectrometry, X-ray diffraction spectrometry, and Fourier transform infrared spectrometry. The specific cation exchange behavior between Fe(3+) and the framework Al(3+) along with the excellent stability of MIL-53(Al) allows highly selective and sensitive detection of Fe(3+) in aqueous solution. The developed method was applied to the determination of Fe(3+) in human urine samples with the quantitative spike recoveries from 98.2% to 106.2%.

  20. Distribución de metales pesados en agua y sedimentos y sus efectos sobre la vida acuática en la cuenca superior del río Santa

    OpenAIRE

    2003-01-01

    El agua es un recurso natural imprescindible para el desarrollo de la vida en todas sus manifestaciones, es un recurso de gran valor para la mayoría de los procesos productivos. Pero también es un recurso agotable. La cuenca superior del Santa comprende al río desde su nacimiento por deshielo en las altas cumbres de la Cordillera Blanca en la quebrada de Tuco hasta Recuay, esta parte alta del río Santa está influenciada por actividad minera, principalmente de la pequeña y micro minería ubicad...