Articles de revues : « American Abrasive Metals Co »

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Li, Zhijie, Fei Ma, Dongshan Li, Shanhong Wan, Gewen Yi, Guofang Geng et Lingyan Guo. « Enhanced Mechanical and Tribological Capabilities of a Silicon Aluminum Alloy with an Electroplated Ni–Co–P/Si3N4 Composite Coating ». Metals 12, n^o 1 (7 janvier 2022) : 120. http://dx.doi.org/10.3390/met12010120.

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Ni–Co–P/Si3N4 composite coatings were fabricated over an aluminum–silicon (Al–Si) substrate using a pulse-current electroplating process, in which the rapid deposition of an intermediate nickel–cobalt layer was used to improve coating adhesion. The microstructure, mechanical, and tribological behaviors of the electroplated Ni–Co–P/Si3N4 composite coating were characterized and evaluated. The results revealed that the electroplated Ni–Co–P/Si3N4 composite coating primarily consisted of highly crystalline Ni–Co sosoloid and P, and a volumetric concentration of 7.65% Si3N4. The electroplated Ni–Co–P/Si3N4 composite coating exhibited hardness values almost two times higher than the uncoated Al–Si substrate, which was comparable to hard chrome coatings. Under lubricated and dry sliding conditions, the electroplated Ni–Co–P/Si3N4 composite coating showed excellent anti-wear performance. Whether dry or lubricated with PAO and engine oil, the composite coating showed minimum abrasive wear compared to the severe adhesive wear and abrasive wear observed in the Al–Si substrate.

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Krakhmalev, P. V. « Abrasion of ultrafine WC-Co by fine abrasive particles ». Transactions of Nonferrous Metals Society of China 17, n^o 6 (décembre 2007) : 1287–93. http://dx.doi.org/10.1016/s1003-6326(07)60264-7.

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Baek, Min-Seok, Ji-Won Kim, Bae-Gun Park, Hee-Sub Park et Kee-Ahn Lee. « Effect of Co Leaching on the Vertical Turning Lathe Wear Properties of Polycrystalline Diamond Compact Manufactured by High Temperature and High Pressure Sintering Process ». Korean Journal of Metals and Materials 58, n^o 7 (5 juillet 2020) : 480–87. http://dx.doi.org/10.3365/kjmm.2020.58.7.480.

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Polycrystalline diamond compact (PDC) has excellent wear resistance, high impact resistance, superior fatigue properties, and has been used in the oil and gas drilling industries. This study investigated the effect of Co leaching on the microstructure, vertical turning lathe (VTL) wear properties of PDCs manufactured by high-temperature and high-pressure (HTHP) sintering. The VTL wear test has the advantage of simulating the actual oil drilling environment by using granite as the workpiece. PDC sintered material that did not receive Co leaching was named HTHP sintered PDC-A, and the material subjected to Co leaching was called Co-leached PDC-B in this study. As a result of XRD analysis of both PDCs, diamond and WC peaks were detected, and only the HTHP sintered PDC-A exhibited some Co peaks. In the HTHP sintered PDC-A, the binder WC and Co were evenly distributed at the diamond interface. However, in the Co-leached PDC-B, some empty spaces were observed at the diamond interface. The HTHP sintered PDCA exhibited a similar or slightly higher VTL wear resistance than the Co-leached PDC-B, but only in the short sliding distance. In the long sliding distance after 9 km, Co-leached PDC-B showed significantly superior wear resistance compared to the HTHP sintered PDC-A. The HTHP sintered PDC-A exhibited both abrasive and adhesive wear behaviors, while the Co-leached PDC-B showed only abrasive wear. Based on the above results, the VTL wear mechanism of PDCs, and ways of improving wear resistance were also discussed.

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Formisano, A., F. Capece Minutolo, A. Caraviello, L. Carrino, M. Durante et A. Langella. « Influence of Eta-Phase on Wear Behavior of WC-Co Carbides ». Advances in Tribology 2016 (2016) : 1–6. http://dx.doi.org/10.1155/2016/5063274.

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Cemented carbides, also known as Widia, are hard metals produced by sintering process and widely used in mechanical machining. They show high cutting capacity and good wear resistance; consequently, they result to be excellent materials for manufacturing cutting tools and sandblast nozzles. In this work, the wear resistance of WC-Co carbides containing Eta-phase, a secondary phase present in the hard metals when a carbon content deficiency occurs, is analyzed. Different mixtures of carbide are prepared and sintered, with different weight percentages of carbon, in order to form Eta-phase and then analyze how the carbon content influences the wear resistance of the material. This characterization is carried out by abrasive wear tests. The test parameters are chosen considering the working conditions of sandblast nozzles. Additional information is gathered through microscopic observations and the evaluation of hardness and microhardness of the different mixtures. The analyses highlight that there is a limit of carbon content below which bad sintering occurs. Considering the mixtures without these sintering problems, they show a wear resistance depending on the size and distribution of the Eta-phase; moreover, the one with high carbon content deficiency shows the best performance.

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Sedlaček, Marko, Katja Zupančič, Barbara Šetina Batič, Borut Kosec, Matija Zorc et Aleš Nagode. « Influence of Precipitation Hardening on the Mechanical Properties of Co-Cr-Mo and Co-Cr-W-Mo Dental Alloys ». Metals 13, n^o 3 (22 mars 2023) : 637. http://dx.doi.org/10.3390/met13030637.

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Co-Cr alloys have good mechanical properties such as high hardness, excellent magnetic properties and good corrosion resistance. For this reason, they are most commonly used as dental and orthopaedic implants. Generally, cast Co-Cr-Mo alloys and forged Co-Ni-Cr-Mo alloys are used for the production of implants. In this study, we investigated two dental alloys, namely, Co-Cr-Mo and Co-Cr-W-Mo alloys. The aim of this study was to determine the effect of heat treatment on the development of the microstructure and to evaluate its influence on the alloys’ mechanical and tribological properties. The samples were first solution-annealed at 1200 °C in an argon atmosphere for 2 h, then quenched in water and subsequently aged at 900 °C in an argon atmosphere for 1, 3 and 12 h. A microstructural analysis was performed using SEM, with EDS for microchemical analysis and EBSD for phase identification. In addition, the Vickers hardness and wear resistance of the two alloys were analysed before and after heat treatment. The Co-Cr-Mo alloy showed better wear resistance and also a generally higher hardness than the Co-Cr-W-Mo alloy. Both alloys showed signs of abrasive and adhesive wear, with carbide particles detaching from the Co-Cr-W-Mo alloy due to the lower hardness of the matrix. The Co-Cr-Mo alloy showed the best abrasion resistance after the longest aging time (12 h), while the Co-Cr-W-Mo alloy showed the best as-cast abrasion resistance. With ageing, the wear resistance of both alloys increased.

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Wege, Frank vom, Birgit Skrotzki et Erhard Hornbogen. « Abrasivverschleiß einer schmelzgesponnenen und nachfolgend angelassenen Co-Basis-Legierung / Abrasive Wear of a Meltspun and Subsequently Annealed Co-Base Alloy ». International Journal of Materials Research 79, n^o 8 (1 août 1988) : 492–98. http://dx.doi.org/10.1515/ijmr-1988-790802.

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González-Pociño, Alejandro, María A. García-García, Florentino Alvarez-Antolin et E. Segurado-Frutos. « Effect of Shot Peening and Nitriding on Toughness and Abrasive Wear Resistance of Powder Metallurgic Steels Highly Alloyed with Vanadium ». Metals 14, n^o 1 (23 décembre 2023) : 22. http://dx.doi.org/10.3390/met14010022.

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Böhler K390 steel is used for cold work tools, with 9% of V, made by using powder metallurgy. In this work, it has been studied the effect of shot peening and nitriding surface treatments on wear resistance and impact toughness of this type of steel. For this purpose, previous changes in several thermal processing factors related to quenching and tempering were carried out. The results allow for an increase in the hardness, impact toughness, and abrasive wear resistance of these steels. An austenitizing treatment at 1100 °C with air cooling and 3 tempering processes at 550 °C is suggested. These conditions foster a lower weight percentage of retained austenite, up to 3%, a higher carbide percentage, up to 15–16% in weight, and a greater impact toughness with no notch, of above 40 J/cm2. If this treatment is combined with further ion nitriding, the maximum level of abrasive wear resistance is reached. The only carbide type present in the microstructure is the MC type. Most of the V, Cr, and Mo contents are present in said carbides. The Co and the W tend to remain in solid solution in the matrix constituent. Both the shot peening treatment as well as ion nitriding offer a considerable increase in hardness, with values of up to 1500–1600 HV. Nevertheless, it has been confirmed that shot peening does not offer any abrasive wear resistance improvement. Such resistance may only be considerably improved by the application of an ionic nitriding treatment. The thickness of the nitrided layer fluctuates between 150 and 175 µm. The carbides are affected by nitriding, reaching levels that are higher than the atomic 10%, at an intermediate depth of the nitrided layer. These values are higher in the matrix constituent, as they are even higher than the atomic 20% in N.

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Somunkiran, I., M. Nursoy et H. Çelik. « Effect of Cr content on microstructure and abrasive wear behaviour of Co-based alloys ». Powder Metallurgy 54, n^o 3 (juillet 2011) : 209–13. http://dx.doi.org/10.1179/174329009x442735.

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Qu, Jun, Albert J. Shih, Ronald O. Scattergood et Jie Luo. « Abrasive micro-blasting to improve surface integrity of electrical discharge machined WC–Co composite ». Journal of Materials Processing Technology 166, n^o 3 (août 2005) : 440–48. http://dx.doi.org/10.1016/j.jmatprotec.2004.09.075.

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Imak, Anil, Musa Kilic et Ihsan Kirik. « Production of Ni-Co-bronze composites with different tic composition by hot pressing ». Science of Sintering, n^o 00 (2023) : 7. http://dx.doi.org/10.2298/sos220404007i.

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Improving microstructural, mechanical, and thermal properties of Ni-Co-Bronze composites is crucial for various applications. In this study, five Ni-Co-Bronze (CuSn) + XTiC (0, 3, 7, 10, and 15 wt.%) composites were produced by using the hot pressing method. The effect of TiC reinforcement rate on each of their microstructure, wear, hardness, and thermal properties was investigated. Within the scope of microstructure analysis, the scanning electron microscope (SEM), electron dispersive spectrometer (EDS), and XRD analysis were employed. Thermal analyses were carried out for thermal differences between the samples. Furthermore, microhardness, impact, and wear tests were run to estimate mechanical behaviors of Ni-Co Bronze + XTiC composite. Experimental results indicated that TiC rate had an important effect on the microstructure, wear-resistance and microhardness of Ni-Co bronze composite. As the TiC reinforcement rate increased, the hardness of Ni-Co Bronze + XTiC composites varied between 180 HV and 450 HV. Consequently, microstructure analysis revealed that there was a serious interaction between reinforcement and matrix. Wear resistance increased with a TiC (7-10) wt. % rate but decreased at high TiC rates. It was clearly seen that the wear pattern was both oxidative and abrasive.

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Purba, Riki Hendra, Kazumichi Shimizu, Kenta Kusumoto, Yila Gaqi et Mohammad Jobayer Huq. « A Study of the Three-Body Abrasive Wear Resistance of 5V/5Nb-5Cr-5Mo-5W-5Co-Fe Multicomponent Cast Alloys with Different Carbon Percentages ». Materials 16, n^o 8 (14 avril 2023) : 3102. http://dx.doi.org/10.3390/ma16083102.

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Since it is well known in the literature that transition metals can form extremely hard carbides and effectively strengthen a material’s matrix, recently, some of them, such as V, Nb, Cr, Mo, and W, have been simultaneously added to cast iron. In addition, it is common to add Co to cast iron to strengthen the material’s matrix. However, the wear resistance of cast iron can also be considerably affected by the addition of C, which is rarely discussed in the literature by the experts. Therefore, the effect of C content (1.0; 1.5; 2.0 wt.%) on the abrasive wear behavior of 5 wt.% V/Nb, Cr, Mo, W, and Co alloys was investigated in this study. An evaluation was conducted using a rubber wheel abrasion testing machine in accordance with ASTM G65 with silica sand (1100 HV; 300 μm) as abrasive particles. The results show that plural carbides (MC, M2C, and M7C3) precipitated on the microstructure of the material, which is not unlike the behavior of other types of carbides as the quantity of C increases. The hardness and wear resistance properties of 5V-5Cr-5Mo-5W-5Co-Fe and 5Nb-5Cr-5Mo-5W-5Co-Fe multicomponent cast alloys increased as the quantity of C increased. However, we observed no significant difference in the hardness between the two materials with the same C additions, while 5Nb presented better wear resistance properties compared to the 5V sample due to the larger size of NbC compared to VC. Therefore, it can be determined that, in this study, the size of the carbide plays a more important role than its volume fraction and hardness.

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BOUZID, Kheireddine, Rim LAMARI, Nasser Eddine BELIARDOUH, Corrine NOUVEAU et Barnali Biswas. « Corrosion and Wear performances analysis of PVD CrMoN/Cr Coatings ». Metallurgical and Materials Engineering 27, n^o 3 (29 septembre 2021) : 397–409. http://dx.doi.org/10.30544/640.

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Tools coated CrN based alloys are currently used in several industries for machining and manufacturing, but present severe wear, limiting their service life. Seeking an alternative, three CrMoN monolayers (~1µm in thickness) coatings with varying in the Mo percentage content were elaborated using the RF magnetron co-sputtering method. These coatings were evaluated and compared with the alloy currently used (CrN) by electrochemical tests in NaCl solution (stationary and no stationary method) and sliding wear tests (ball-on-disc configuration) performed at room temperature. The results indicate that the samples coated with CrMoN presented better performance against wear and corrosion than the uncoated sample. Among the coatings, the labeled C1 (27 % Mo) showed the best corrosion resistance as it presents a positive corrosion potential Ecorr. However, the best wear resistance (lowest coefficient of friction) was shown by coating labeled C4 (33 % Mo). All of the tested specimens underwent abrasive wear in addition to adhesive wear.

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Kučera, Marián, et Michaela Hnilicová. « Changes in the Key Physicochemical Parameters and Selected Trace Elements of Oil Due to Its Use in Hydraulic System of Woodworking Equipment ». Acta Technologica Agriculturae 25, n^o 3 (12 août 2022) : 137–43. http://dx.doi.org/10.2478/ata-2022-0021.

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Abstract The research presented supported a comprehensive assessment of the condition of real oil samples of the HM quality class and VG 46 viscosity grade as functions of oil usage time in the hydraulic system of two round timber sorting and transport carriages (RSTWI and RSTWII) Baljer & Zembrod intended for handling wood logs by following the degradation and concentration of abrasive metals in the oil. The oil data were collected every Δ = 500 operating hours during one year by off-line monitoring of hydraulic oil. Measured values were compared to the acceptability limits. Multivariate associations were analysed using a principal component analysis (PCA; Statistica 12.0) to describe the patterns of co-variation among the examined traits. Based on the data obtained, it was observed that the oil in RSTWI was more oxidatively stressed in contrast to the oil in RSTWII despite it being subjected to an excessive wear mode.

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Harsha, Sudhir, Dheerendra Kumar Dwivedi et Ajai Agrawal. « Investigations on the Abrasive Wear Behaviour of Flame Sprayed Ni–Cr–Co–Si Alloy Coating Deposited on Mild Steel Substrate ». ISIJ International 46, n^o 10 (2006) : 1473–78. http://dx.doi.org/10.2355/isijinternational.46.1473.

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Razumov, Nikolay, Dmitriy Masaylo, Mark Kovalev, Ekaterina Volokitina, Alina Mazeeva et Anatoliy Popovich. « Structure and Wear Resistance of Composite TiC-NiMo Coating Produced by L-DED on Ti-6Al-4V Substrate ». Metals 13, n^o 12 (23 novembre 2023) : 1925. http://dx.doi.org/10.3390/met13121925.

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Fabrication of W- and Co-free wear-resistant cermets is a vital task in modern machinery due to the toxicity of Co-based products and poor availability of Co and W containing raw materials. In this paper, a TiC-NiMo coating produced by laser-directed energy deposition (L-DED) on a Ti-6Al-4V substrate was demonstrated. Mechanical alloying of TiC, Ni and Mo powders followed by spray-drying was proposed to fabricate a feedstock spherical composite powder suitable for an L-DED machine. It was shown that this method is more applicable in the case of a TiC-containing composition than gas atomization and plasma spheroidization methods. The size of the resulting particles was in the range of 10–100 μm while the size of the 70 vol.% was in the range of 45–75 μm. L-DED provided a good adhesion of the coating, though the presence of pores and transverse cracks was also observed. The coating’s hardness was up to 1500 HV, which is not inferior to the hardness of known TiC-based cermets and is promising for obtaining a good wear resistance of the coating. It was shown that it depended on the thickness due to the mixing zone influence. The coating structure contained TiC- and Mo-based precipitates and a Ni-based binder. The weight loss of the coating samples after an abrasive wear test with 4000 revolutions of a testing wheel was 0.0464 g and that can be considered insignificant. The wear did not lead to the appearance of new defects and cleavage of the coating. Further optimization of the component ratio and L-DED parameters could help to improve the performance of the coating and make this technology rather promising to improve the wear resistance of machinery parts working in high-wear environments.

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Sarfraz, Muhammad, Qazi Mohammed Omar, Z. Gulfraz, Farhat Yasmeen et Javeed Ashraf Awan. « Estimation of toxic metal contamination levels in beverages samples collected from Lahore city in Pakistan. » Journal of the Pakistan Institute of Chemical Engineers 47, n^o 1 (17 juillet 2019) : 25–34. http://dx.doi.org/10.54693/piche.04713.

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The present study was conducted to evaluate the risk associated to human health by heavy metals through the intake of beverages (fruit juices, soft and energy drinks) excessively used in city Lahore, Pakistan. The concentration in ppm of heavy metals (Pb, Cr, Co, Cd, Zn and Ni) in 17 popular beverages has been investigated by using Flame Atomic Absorption Spectrophotometer (AAnalyst 400-PerkinElmer). A range of standard solutions were prepared according to the standard methods governed by American Public Health Association. It has been observed that concentration of some heavy metals (i.e Pb, Cr, Co, Zn and Ni) in all collected samples (i.e 17) were found close to the Standard permissible limits provided by World Health Organization, United Sates Environmental Protection Agency, and Pakistan Standards Quality Control Authority. However, all samples were free from any detectable concentration levels of Cd.

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Li, Zicheng, Zhihong Li, Aiju Zhang et Yumei Zhu. « Synergistic effect of α-Al2O3 and (NH4)3AlF6 co-doped seed on phase transformation, microstructure, and mechanical properties of nanocrystalline alumina abrasive ». Journal of Alloys and Compounds 476, n^o 1-2 (mai 2009) : 276–81. http://dx.doi.org/10.1016/j.jallcom.2008.08.072.

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Krutskii, Yu L., T. S. Gudyma, T. M. Krutskaya, А. О. Semenov et A. V. Utkin. « Carbides of transition metals : Properties, application and production. Review. Part 2. Chromium and zirconium carbides ». Izvestiya. Ferrous Metallurgy 66, n^o 4 (19 août 2023) : 445–58. http://dx.doi.org/10.17073/0368-0797-2023-4-445-458.

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The properties, application, and methods for producing chromium and zirconium carbides are considered. These carbides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technology. Chromium carbide is used mainly as component of surfacing mixtures to create protective coatings that resist intensive abrasive wear, including at elevated temperatures (up to 800 °C) in oxidizing environments. This compound is also used in the manufacture of tungsten-free hard alloys and carbide steels. Chromium carbide, along with vanadium carbide, is used as a grain growth inhibitor in WC – Co hard alloys. Powdered zirconium carbide can be used to polish the surface of items made of ferrous and non-ferrous metals. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation, to determine the permissible content of impurities in the initial components. This leads to the existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.

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Haye, Jennifer M., Peter H. Santschi, Kimberly A. Roberts et Sammy Ray. « Protective Role of Alginic Acid Against Metal Uptake by American Oyster (Crassostrea virginica) ». Environmental Chemistry 3, n^o 3 (2006) : 172. http://dx.doi.org/10.1071/en06015.

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Environmental Context. Trace metals are both micronutrients and toxicants, depending on concentration, and in coastal waters they bind to natural organic matter including nanoparticles. The binding type affects trace metal bioavailability to bivalves such as oysters, which ingest metals through water and food particles. Bivalves are biomonitors because of the high trace metal concentrations, especially Cu and Zn, in their tissues. Here, the polysaccharide alginic acid is shown to protect against the assimilation and bioavailability of trace metals to American oysters. Abstract. Little is known about how colloidal macromolecular organic matter (COM) modifies the bioavailability of toxic metals to aquatic organisms. In order to understand the physical and chemical properties of COM on the bioavailability of some metals to estuarine bivalves used as biomonitors, American oysters (Crassostrea virginica) were exposed to natural COMs and model acid polysaccharides (APS, alginic acid (AA), kappa carrageenan (CAR), and latex particles), and natural colloidal organic carbon (COC), tagged with either radioactive Ag, Cd, Co, Cr, Fe, Hg or Zn, or 14C-labelled sugar OH groups. Filter-feeding oysters efficiently removed latex particles 0.04 µm in diameter, with removal half-times of 2.5–5.5 h, equivalent to a filtration rate of approximately 3 L day–1 g–1. Thus, AA protects against metal uptake by oysters, which is confirmed by metal dry-weight concentration factors (DCFs) similar to, or lower than, those for 14C-labelled AA. However, metal-DCFs for CAR and COC were higher than for 14C-labelled counterparts, suggesting that in these treatments, metal uptake was enhanced over that of carbon. The 14C-labelled AA was taken up significantly more than other 14C-labelled organics, suggesting different behavior in the digestive tract. Bioavailabilty of metals bound to organic nanoparticles with different nutritional and physiological properties is not fully understood, and will require further experiments.

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Liu, Yourong, Yunfei Qiao, Traugott E. Fischer, Jianhong He et Enrique J. Lavernia. « Near-nanostructured WC-18 pct Co coatings with low amounts of non-WC carbide phase : Part II. Hardness and resistance to sliding and abrasive wear ». Metallurgical and Materials Transactions A 33, n^o 1 (janvier 2002) : 159–64. http://dx.doi.org/10.1007/s11661-002-0014-8.

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Blake, Johanna M., Sumant Avasarala, Kateryna Artyushkova, Abdul-Mehdi S. Ali, Adrian J. Brearley, Christopher Shuey, Wm Paul Robinson et al. « Elevated Concentrations of U and Co-occurring Metals in Abandoned Mine Wastes in a Northeastern Arizona Native American Community ». Environmental Science & ; Technology 49, n^o 14 (9 juillet 2015) : 8506–14. http://dx.doi.org/10.1021/acs.est.5b01408.

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Scheid, Adriano, et Ana Sofia Clímaco Monteiro de Oliveira. « Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys ». Soldagem & ; Inspeção 18, n^o 4 (décembre 2013) : 322–28. http://dx.doi.org/10.1590/s0104-92242013000400004.

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CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

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Rutkovskіy, Anatoly, Sergiy Markovych, Sergiy Mahopets et Viktor Markovych. « Wear resistance of titanium alloy VT1-0 with a modified surface under abrasive action ». Central Ukrainian Scientific Bulletin. Technical Sciences 2, n^o 8(39) (2023) : 41–47. http://dx.doi.org/10.32515/2664-262x.2023.8(39).2.41-47.

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The cost of rebuilding machine parts as a result of wear is enormous and rising every year. At a US symposium on reducing wear in machinery, the general consensus was that wear management is central to solving national problems such as energy conservation, material reduction, and ensuring the reliability and safety of mechanical systems. Nitriding significantly increases the wear resistance of metals and alloys. The formation of chemical compounds in titanium alloys by introducing nitrogen or increasing its concentration limit changes the rate of chemical reactions and the kinetics of oxide film growth, and increases their adhesion to the substrate. This leads to a decrease in the intensity of adhesive node formation and improves the tribological characteristics of titanium alloys. Therefore, it is necessary to study a titanium alloy with a hardened nitrided layer to obtain experimental results to determine the regularity of the influence of diffusion saturation parameters on wear resistance under abrasive conditions. The universal installation "VIPA-1" was used for vacuum ion nitriding in the pulse mode and the formation of diffusion layers on the surface. Technological parameters of vacuum ion nitriding in the pulse mode: temperature - 550°C, pressure - 25-150 Pa, processing time - 10 hours, ratio of reaction gases - 80% Ag + 20% N2. For experimental studies, samples of VT1-0 titanium alloy with dimensions of 30x30 mm and a thickness of 5 mm were used. The surface hardening of the samples was carried out uniformly around the entire perimeter, which ensures a uniform thickness of the diffusion layer. The analysis of the operating conditions of the friction surfaces of most structural elements made it possible to use the installation for bench tests according to the scheme of wear with a free abrasive (Brinell method). Wear tests were carried out on an experimental setup in accordance with GOST 23.208-79 (Fig. 2). The friction process was modelled in the presence of a free, not rigidly fixed abrasive, which coincides with the American standard ASTM C 6568. The experiment was carried out at a sliding speed of 0.158 m/s, a load of 20 kg (with a shoulder of 272 mm) and a friction path of 50 m. Steel 45, hardened to a hardness of 480-500 HB, was used as a reference. The wear body was a disc made of VT1-0 titanium alloy with a diameter of 100 mm and a thickness of 3.5 mm. On the basis of experimental studies, it has been established that the main mechanisms for increasing the wear resistance of titanium alloys as a result of the process of diffusion saturation of the surface with nitrogen during vacuum ion nitriding in the pulse mode are strengthening of the surface layers; creation of a favourable residual stress pattern; change in the patterns of deformation of the surface layers; change in the chemical and adhesive properties of the surface; transfer of diffusing nitrogen atoms into the depth of the matrix during friction due to the tribodiffusion effect. Conclusions. 1. Maximum wear rate of titanium alloy VT1-0 without hardening. 2. The effect of thermocyclic nitriding increases the wear resistance of VT1-0 alloy: in sand - 3 times; in water + sand - 3.5 times; in salt + sand - 2.5 times. 3. The effect of isothermal nitriding increases the wear resistance of VT1-0 alloy: in sand - 4 times; in water + sand - 3.5 times; in salt + sand - 2.5 times.

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de Boyrie, Maria E., et Ivelina Pavlova. « Equities and Commodities Comovements : Evidence from Emerging Markets ». Global Economy Journal 18, n^o 3 (26 avril 2018) : 20170075. http://dx.doi.org/10.1515/gej-2017-0075.

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The financialization of commodities and their inclusion in financial portfolios as part of an investment strategy may result in higher correlations and volatility spillovers between commodity and equity markets. In this paper, we estimate the correlation between equity markets and commodities using the dynamic conditional correlation (DCC) model, while emphasizing the differences between emerging and developed markets co-movements with commodities. The results reveal that certain emerging markets, especially those in Asia, show a much lower level of co-movement with commodities than developed markets do, while Latin American equities exhibit a higher level of integration with commodities. Furthermore, it is found that both agricultural and precious metals commodities offer better diversification possibilities in the less developed markets. We also find that increases in the CBOE Volatility Index (VIX) are related to higher agriculture commodities-equities correlations, while commodity net index investment has limited explanatory power in our study.

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Akinwekomi, Akeem, et Farid Akhtar. « Microstructural, Mechanical, and Electrochemical Characterization of CrMoNbTiZr High-Entropy Alloy for Biomedical Application ». Materials 16, n^o 15 (28 juillet 2023) : 5320. http://dx.doi.org/10.3390/ma16155320.

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High-entropy alloys (HEA) with superior biocompatibility, high pitting resistance, minimal debris accumulation, and reduced release of metallic ions into surrounding tissues are potential replacements for traditional metallic bio-implants. A novel equiatomic HEA based on biocompatible metals, CrMoNbTiZr, was consolidated by spark plasma sintering (SPS). The relative sintered density of the alloy was about 97% of the theoretical density, indicating the suitability of the SPS technique to produce relatively dense material. The microstructure of the sintered HEA consisted of a BCC matrix and Laves phase, corresponding to the prediction of the thermodynamic CALPHAD simulation. The HEA exhibited a global Vickers microhardness of 531.5 ± 99.7 HV, while the individual BCC and Laves phases had hardness values of 364.6 ± 99.4 and 641.8 ± 63.0 HV, respectively. Its ultimate compressive and compressive yield strengths were 1235.7 ± 42.8 MPa and 1110.8 ± 78.6 MPa, respectively. The elasticity modulus of 34.9 ± 2.9 GPa of the HEA alloy was well within the range of cortical bone and significantly lower than the values reported for commonly used biomaterials made from Ti-based and Cr–Co-based alloys. In addition, the alloy exhibited good resistance to bio-corrosion in PBS and Hanks solutions. The CrMoNbTiZr HEA exhibited an average COF of 0.43 ± 0.06, characterized mainly by abrasive and adhesive wear mechanisms. The CrMoNbTiZr alloy’s mechanical, bio-corrosion, and wear resistance properties developed in this study showed a good propensity for application as a biomaterial.

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Okeke, David Okechukwu, et Jonathan Chinenye Ifemeje. « Levels of heavy metals in soils and food crops cultivated within selected mining sites in Ebonyi State, Nigeria ». Health and Environment 2, n^o 1 (2021) : 84–95. http://dx.doi.org/10.25082/he.2021.01.003.

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The level of heavy metals (Fe, Cu, As, Pb, Cd, Mg, Ca, Hg, Ni, Cr, Zn, Ag, Co, Mo, Se and Al) in soils and food crops (okra, cassava and rice) cultivated within selected mining sites in Ebonyi State, Nigeria were determined using FS240AA Atomic Absorption Spectrophotometer (AAS) according to the method of American Public Health Association (APHA). Soil samples were collected from Enyigba mining site, Ikwo mining site, AmeriAmekamining site, Izza mining site, MkpumeAkwatakwa mining site and MpumeAkwaokuku mining site while the food crop samples (okra, cassava and rice) were collected from the farmlands within the mining sites. Control samples were collected 500m away from the mining destinations were there was no evidence of mining activities on the soils. A total of sixty sub-samples and six control soil samples were collected for this study. Generally, the values of all the heavy metals analyzed for soil and food crop samples were higher than the values recommended by the World Health Organization (WHO), and those from the control site suggesting possible mobility of the metals from mining sites to farmlands through leaching and runoffs. The findings in this study also revealed that the food crops contain heavy metals exceeding the maximum permissible concentration, and could be detrimental to human health when they are consumed.

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Sahli, Leila, Fatima-Zohra Afri-Mehennaoui, Mohamed El Hadef El Okki, Christian Blaise et Smail Mehennaoui. « Spatial and seasonal variations and ecotoxicological significance of sediment trace metal concentrations in Kebir-Rhumel basin (Northeast of Algeria) ». Water Science and Technology 64, n^o 8 (1 octobre 2011) : 1759–66. http://dx.doi.org/10.2166/wst.2011.693.

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This study sought to assess sediment contamination by trace metals (cadmium, chromium, cobalt, copper, manganese, nickel, lead and zinc), to localize contaminated sites and to identify environmental risk for aquatic organisms in Wadis of Kebir Rhumel basin in the Northeast of Algeria. Water and surficial sediments (0–5 cm) were sampled in winter, spring, summer and autumn from 37 sites along permanent Wadis of the Kebir Rhumel basin. Sediment trace metal contents were measured by Flame Atomic Absorption Spectroscopy. Trace metals median concentrations in sediments followed a decreasing order: Mn > Zn > Pb > Cr > Cu > Ni > Co > Cd. Extreme values (dry weights) of the trace metals are as follows: 0.6–3.4 μg/g for Cd, 10–216 μg/g for Cr, 9–446 μg/g for Cu, 3–20 μg/g for Co, 105–576 μg/g for Mn, 10–46 μg/g for Ni, 11–167 μg/g for Pb, and 38–641 μg/g for Zn. According to world natural concentrations, all sediments collected were considered as contaminated by one or more elements. Comparing measured concentrations with American guidelines (Threshold Effect Level: TEL and Probable Effect Level: PEL) showed that biological effects could be occasionally observed for cadmium, chromium, lead and nickel levels but frequently observed for copper and zinc levels. Sediment quality was shown to be excellent for cobalt and manganese but medium to bad for cadmium, chromium, copper, lead, nickel and zinc regardless of sites.

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Okeke, David Okechukwu, Jonathan Chinenye Ifemeje et Victor Chukwuemeka Eze. « Determination of the levels of heavy metals and physicochemical properties of borehole water within selected mining sites in Ebonyi State, Nigeria ». Health and Environment 3, n^o 1 (2022) : 162–68. http://dx.doi.org/10.25082/he.2022.01.003.

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The level of heavy metals (Pb, Cd, As, Cr, Ni, Co, Zn) and physicochemical parameters in borehole water sources within selected mining sites in Ebonyi State, Nigeria were determined using FS240AA Atomic Absorption Spectrophotometer (AAS) according to the method of American Public Health Association (APHA). Water samples were collected from Enyigba mining site, Ikwo mining site, Ameri Amekamining site, Izza mining site, Mkpume Akwatakwa mining site and Mpume Akwaokuku mining sites. Composite water samples were collected within the mining locales and 500 metres away from the mining locations using two liters plastic jars. Similarly, the control samples were taken from Abakaliki (about 15 km away from mining area) where there was no evidence of mining activity. A total of 14 sub-samples were collected for this study. Generally, the levels of heavy metals in the borehole water samples were higher than the values recommended by the World Health Organization (WHO). This however suggests a possible mobility of the metals from mining sites into the groundwater sources through leaching. The findings from this study have revealed the need to purify borehole water within mining areas prior to industrial and domestic use.

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Achadu, Abah M., et Idara-Obong E. Akpan. « Treatment and Characterization of Wastewater from Tissue Paper Making Industry Using Bamboo as Raw Material ». Sustainability in Environment 7, n^o 1 (3 février 2022) : p85. http://dx.doi.org/10.22158/se.v7n1p85.

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This article focused on the treatment and characterization of wastewater from tissue paper making industry located in AkwaIbom State which uses bamboo as raw material. The wastewater samples generated during the pulping and bleaching processes were collected, analyzed to determine the pollution loads and thereafter treated to ascertain its suitability for disposal into the environment using standard methods by American Public Health Association (APHA). The results obtained before treatment were pH (7.42 and 4.49), EC (316µS/cm and 47µS/cm), TDS (158mg/l and 24mg/l), Turbidity (19.3NTU and 28.7NTU), BOD5 (74.02mg/l and 62.00mg/l), COD (140.30mg/l and 120.40mg/l), TOC (10.3% and 7.1%), selected heavy metals like, Pb (0.281mg/l and 0.273mg/l), Ni (0.115mg/l and 0.117mg/l), and Co (0.193mg/l and 0.208mg/l). The corresponding values after treatment were pH (8.08 and 7.88), EC (4.00µS/cm and 4 µS/cm), TDS (2.00mg/l and 2mg/l), Turbidity (9.6NTU and 5.1NTU), BOD5 (4.06mg/l and 4.11mg/l), COD (14.20mg/l and 12.80mg/l), TOC (0.1% and 0.1%), with selected heavy metals like Pb (0.040mg/l and 0.041mg/l), Ni (0.003mg/l and 0.005mg/l) and Co (0.011mg/l and 0.015mg/l). The average extent of treatment was slightly above 70% for the pulping unit sample and about 80% for that from the bleaching unit. The study recommends wastewater treatment before disposal.

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Mahdi, R. S., et F. K. Omran. « DETERMINATION OF HEAVY METALS CONCENTRATION OF LOCAL AND IMPORTED WHEAT GRAINS STORAGE AND WHEAT FLOUR IN SOME SILOS of BAGHDAD CITY ». IRAQI JOURNAL OF AGRICULTURAL SCIENCES 52, n^o 5 (21 octobre 2021) : 1139–49. http://dx.doi.org/10.36103/ijas.v52i5.1452.

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The aim of this study was to estimate the levels of some toxic heavy metals such as (Cd, Pb,Cr,Ni,Zn,Cu,Fe,Co,As)by using the X-Ray fluorescence .in a total of forty-one samples of wheat grains which were (local, American, Australian, Canadian and mixing mills) samples collected randomly and seasonally from three silos in Baghdad ,also wheat flour collected from mills related to the manufactured of grains of each silo. The results showed that the levels of (Cadmium, Lead and Chromium) were surpassed the permissible safe limits according to FAO/WHO (2001).It was found that the highest concentration of cadmium detected in wheat flour in AL Dora silo for summer and spring seasons were 12.6mg/kg, as well as the high level of lead 1.021mg/kg detected in AL Dora silo in local wheat for winter and summer seasons and wheat flour for spring season, also in Australian wheat for spring season in Taji silo. Finally, the high value of chromium content was in wheat flour in Taji silo for spring season (4.686) mg/kg. Generally, analysis of these data shows significant effects (P≤0.05) of most samples analyzed for Cd >Pb >Fe >Zn >Cu >Ni >Cr >Co while AS show no significant difference in all samples.

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Hoffman, Jessica F., et John F. Kalinich. « Effects of Incubation of Human Brain Microvascular Endothelial Cells and Astrocytes with Pyridostigmine Bromide, DEET, or Permethrin in the Absence or Presence of Metal Salts ». International Journal of Environmental Research and Public Health 17, n^o 22 (11 novembre 2020) : 8336. http://dx.doi.org/10.3390/ijerph17228336.

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Gulf War Illness (GWI) is a chronic, multi-symptom illness suffered by over one-third of American military veterans who served in the Persian Gulf War between 1990 and 1991. No current single-exposure scenario accounts for all the symptoms observed in GWI, and instead may be due to a multi-exposure scenario. As a larger effort to understand how one category of multi-exposure scenarios of organic compounds such as nerve gas prophylactic pyridostigmine bromide, or insecticides/pesticides such as N,N-diethyl-m-toluamide (DEET) and permethrin, plus heavy metals found in inhaled dust particles (Al, Fe, Ni, Sr, DU, Co, Cu, Mn, and Zn) might play a role in neural aspects of GWI, we begin this initial study to examine the toxicity and oxidative damage markers of human brain endothelial cell and human astrocyte cell cultures in response to these compounds. A battery of cytotoxicity assessments, including the MTT assay, Neutral Red uptake, and direct microscopic observation, was used to determine a non-toxic dose of the test compounds. After testing a wide range of doses of each compound, we chose a sub-toxic dose of 10 µM for the three organic compounds and 1 µM for the nine metals of interest for co-exposure experiments on cell cultures and examined an array of oxidative stress-response markers including nitric oxide production, formation of protein carbonyls, production of thiobarbituric acid-reactive substances, and expression of proteins involved in oxidative stress and cell damage. Many markers were not significantly altered, but we report a significant increase in nitric oxide after exposure to any of the three compounds in conjunction with depleted uranium.

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Diaz, Lorena, Juan Solano, Rafael Rios, Lina P. Carvajal, Jose M. Munita, Sandra Rincon, Cesar Arias et Jinnethe Reyes. « 1214. High Frequency of Genes Encoding Resistance to Heavy Metals in Methicillin-Resistant Staphylococcus aureus (MRSA) Endemic Lineages From South America ». Open Forum Infectious Diseases 5, suppl_1 (novembre 2018) : S368. http://dx.doi.org/10.1093/ofid/ofy210.1047.

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Abstract Background MRSA-USA300 is a community-associated clone that has spread worldwide, becoming the most successful clone in the USA. Since 2005, the MRSA-USA300 Latin-American Variant (USA300-LV) has disseminated in community and hospitals in Northern South America. Phylogenetic analysis revealed that USA300-LV is not derived from the USA300 (NA-USA300) but rather, the two clones diverged from a common ancestor. During their evolution, NA-USA300 strains incorporated the ACME element and USA300-LV acquired a copper and mercury resistance mobile element designated COMER. Interestingly, contamination by heavy metals in South American has been recently highlighted and could be driving the selection of resistant genetic lineages. We investigated the frequency of merA, merB, and copB in genomes of clinical isolates of S. aureus from Latin America (LA). Methods The presence of merA/merB and copB encoding mercury and copper resistance, respectively, were investigated in 515 S. aureus sequenced genomes recovered from bacteremic patients in hospitals from nine Latin American hospitals trough BLAST searches. Results The prevalence of merAB in S. aureus was 35% (181 out of 515 genomes). Interestingly, among 181 merAB-positive S. aureus, 174 were MRSA (96%). Moreover, 71%, 60%, 59%, and 51% of MRSA genomes from Peru, Ecuador, Colombia, and Venezuela, respectively, harbored mercury resistance genes. Similarly, 65%, 60%, and 22% of MRSA genomes from Ecuador, Colombia, and Venezuela, contained the copB gene. Among 174 MRSA harboring merAB, ST8 and ST5 were the most predominant lineages in (43% and 45% of genomes, respectively). In contrast, among 95 MRSA carrying copB, ST8 was the most frequent lineage (96% of isolates). MRSA from countries with high prevalence of mercury genes showed association with ST5 and ST8. 88% of Colombian and 87% of Ecuadorian MRSA harboring merAB belonged to ST8 lineage, whereas ST5 was predominant in 88% of Peruvian MRSA. In Venezuela, ST5 and ST8 were found in 44% and 33%, respectively, of MRSA positive for merAB. Conclusion High levels of mercury in rivers of Colombia, Ecuador and Peru has been reported. Thus, the prevalence of heavy metal resistance genes in MRSA clinical isolates suggest an adaptation of endemic genotypes to heavy metal contamination caused by activities like metal mining. Disclosures J. M. Munita, Pfizer: Grant Investigator, Research grant. C. Arias, Merck & Co., Inc.: Grant Investigator, Research support. MeMed: Grant Investigator, Research support. Allergan: Grant Investigator, Research support.

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K. Manoj, J., U. Arunachalam, M. Mathanbabu et A. Kajavali. « Mechanical and heat transfer behaviour of electro-deposited nickel-zirconia coating ». Bulletin of the Chemical Society of Ethiopia 38, n^o 5 (12 juillet 2024) : 1439–52. http://dx.doi.org/10.4314/bcse.v38i5.19.

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Thermal barrier coatings (TBCs) are often applied to base metals exposed to excessive temperatures to protect them from the harsh operating thermal cycle load conditions and to enhance their functionality. For this research, nickel and zirconia was coated over a mild steel substrate by electro-deposition or co-deposition method. While selecting appropriate electro-deposition parameters, this study analyses the convection and conduction heat transfer characteristics and mechanical behaviours of a nickel-zirconia co-deposit over a mild steel substrate. The better-quality deposition is formed with thicknesses of 10 μm and 50 μm. The microstructure and morphological analyses were conducted using scanning electron microscope (SEM). The phase analysis was conducted using X-ray diffraction analysis (XRD). The porosity, hardness and wear behaviours were measured as per the American Society for Testing and Materials (ASTM). The results showed that nickel-zirconia coating has better performance. The coating's convection and conduction heat transfer potential are investigated using a specially designed and constructed experimentation apparatus. Compared to an uncoated panel, heat transfer studies on nickel-zirconia coatings demonstrate that nano-coatings with a particle size of about 92 nm show a significant temperature drop with varied coating thicknesses and heat inputs for different heat inputs. KEY WORDS: Thermal barrier coatings, Electro deposition, Conduction heat transfer, Convection heat transfer, Nickel-Zirconia Bull. Chem. Soc. Ethiop. 2024, 38(5), 1439-1452. DOI: https://dx.doi.org/10.4314/bcse.v38i5.19

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Boschee, Pam. « Comments : New Year Marks JPT’s 75th Anniversary ». Journal of Petroleum Technology 76, n^o 01 (1 janvier 2024) : 10–11. http://dx.doi.org/10.2118/0124-0010-jpt.

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We’re excited to begin the year with the commemoration of JPT’s 75th anniversary. This issue launches our special features dedicated to JPT’s reporting of technology and practices over the past 7½ decades. Emerging Technology Senior Editor Stephen Rassenfoss and Senior Technology Editor Trent Jacobs penned this month’s articles highlighting innovations in drilling, completions, and reservoir engineering. Each month, our editors will dive into the archives to round up milestones of industry advancements and achievements as reported in JPT. Since its inaugural issue in January 1949, JPT has remained true to its mission of reporting the technological and scientific learnings and advancements in the global oil and gas industry. Built upon a strong technical foundation, it continues to draw upon the expertise and knowledge of industry experts to disseminate up-to-date, relevant information to SPE members from all disciplines. JPT’s evolution began with The American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), founded in 1871 in Wilkes-Barre, Pennsylvania. It was one of the first national engineering societies established in the US. In subsequent years, AIME was joined by four other engineering founder societies—The American Society of Mechanical Engineers (ASME), the American Institute of Electrical Engineers (now the Institute of Electrical and Electronics Engineers [IEEE]), the American Society of Civil Engineers (ASCE), and the American Institute of Chemical Engineers (AIChE)—and formed the United Engineering Foundation. (US President Herbert Hoover, a mining engineer, served as AIME’s president in 1920.) As AIME itself continued to grow, it decentralized and formed four independently operated member societies: SME (Society for Mining, Metallurgy, and Exploration); TMS (The Minerals, Metals, and Materials Society); AIST (Association for Iron & Steel Technology); and SPE (Society of Petroleum Engineers). AIME had as part of its membership a small, but growing, number of petroleum engineers. These members had specific technological issues far removed from their peers in the older, more-established engineering disciplines. The AIME Petroleum Branch Executive Committee (whose members represented companies such as The Pure Oil Co., Dowell Inc., Humble Oil and Refining Co., and the Texas Co.) determined that the best way to meet this group’s needs was to develop a “publication so dominantly petroleum as to secure wide reader interest,” one that would “rapidly gain the respect of the industry.” Over the years, that goal was achieved. JPT came to be recognized worldwide as the source for authoritative technical information in the petroleum industry. JPT’s first issue included four technical papers, one of which was “A Hydraulic Process for Increasing the Productivity of Wells.” The paper’s author, J.B. Clark, noted, “To date the process has been used in 32 jobs on 23 wells in 7 fields, resulting in a sustained increase in production in 11 wells.” The hydraulic fracturing techniques for well stimulation that he discussed have been responsible for the subsequent recovery of billions of barrels of oil. Also, bear in mind that the world’s total crude oil production in 1949 was about 3.8 billion bbl, less than the projected total US annual production in 2023—4.7 billion bbl. Other articles related to the oil and gas business were “Private Financing of Oil-Producing Properties” and “Middle Eastern Oil and Its Importance to the World.” Interestingly, although the content is outdated, both topics remain relevant today, 75 years later. Join us each month to explore our rich history and follow us on LinkedIn. All issues of JPT from 1949 to date are available in OnePetro. Even a cursory glance at the titles of the papers will show the remarkable evolution of technology over the years. We wish you the best in 2024, both in your professional and personal lives.

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Dugga, Princy, Shamsh Pervez, Rakesh Kumar Sahu, Madhuri Verma, Shahina Bano et Manas Kanti Deb. « Spatiotemporal Variation In Groundwater Quality Of India During Last 15 Years : A Review ». Journal of Ravishankar University (PART-B) 30, n^o 1 (30 janvier 2021) : 41–52. http://dx.doi.org/10.52228/jrub.2017-30-1-5.

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Groundwater resource in this few decades has been challenging in India due to intense agricultural, industrial and mining activities which make groundwater quality exposed to contaminants. This review article deals with results of groundwater quality monitoring and assessment works conducted in India during the year 2000 to 2015. Previously published research articles of study region with the theme of groundwater quality have been discussed for concentrations of heavy metals, ions, water-soluble organics and inorganics along with its associated health impacts. Several methodologies were used for various chemical contaminants quantification and a wide range of statistical approaches was also applied for their source identification and/or apportionment. The major groundwater pollutants were F? , NO? , As, V, Cd, Cr, Cu, Fe, Pb, Co, Mn, Ni, Zn, Polycyclic Aromatic Hydrocarbons (PAHs), Organochlorine Pesticides (OCPs) etc. monitored in India in higher concentration than standard permissible limits regulated by various international and national agencies like World Health Organization (WHO), United States Environmental Protection Agency (USEPA), American Publi c Health Association (APHA) and Bureau of Indian Standards (BIS). Studies reported that millions of people are suffering from chronic heavy metal poisoning causing cancer, cardiovascular diseases, affecting central nervous system, brain, liver, kidney etc., while 1.6 million children expire every year from ailment for which polluted drinking water is a primary cause.

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Duliu, Octavian G., Carmen I. Cristache, Ana-Voica Bojar, Gheorghe Oaie, Otilia-Ana Culicov, Marina V. Frontasyeva et Emil Constantinescu. « The Geochemistry of 1 ky Old Euxinic Sediments of the Western Black Sea ». Geosciences 9, n^o 11 (23 octobre 2019) : 455. http://dx.doi.org/10.3390/geosciences9110455.

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To get more data on the geochemistry of Black Sea euxinic sediments, a 50-cm core was collected at a depth of 600 m on a Western Black Sea Continental Platform slope. The core contained unconsolidated sediments rich in cocoolithic ooze and mud. Epithermal Neutron and Prompt Gamma Activation Analysis were used to determine the content of nine major (Na, Mg, Al, Si, K, Ca, Ti, Mn, and Fe as oxides) and 32 trace elements (Cl, Sc, V, Cr, Co, Ni, Zn, As, Se, Br, Rb, Sr, Zr, Mo, Sn, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Ta, W, Th, and U) with a precision varying between 3 and 9%. The core contained unconsolidated sediment rich in coccolithic ooze and mud. Previous 210 Pb geochronology suggests an age of ∼1 ky of considered sediments. Major components distribution showed that, except for Cl and Ca, the contents of all other elements are similar to Upper Continental Crust (UCC) and North American Shale Composite (NASC). The distribution of the 32 trace elements showed similarities to the UCC, except for redox-sensitive metals Fe, Se, Mo, and U, of which the significantly higher content reflects the presence of euxinic conditions during deposition. A chondrite normalized plot of nine rare earth elements indicated a similarity to UCC and NASC, suggesting a continental origin of sedimentary material.

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Behret, H. « R. W. Peters (Ed.), B. Mo Kim (Co-ed.) : Separation of Heavy Metals and Other Trace Contaminants, American Institute of Chemical Engineers, New York 1985. 203 Seiten, Preis : S 40.-(für AIChE-Mitglieder ermäßigt). » Berichte der Bunsengesellschaft für physikalische Chemie 90, n^o 11 (novembre 1986) : 1101–2. http://dx.doi.org/10.1002/bbpc.19860901154.

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Srivastava, Aruesha, Neha Shaik, Yunrui Lu, Matthew Chan, Alos Diallo, Serin Han, Ramsey Steiner et al. « Abstract 4949 : Multimodal analysis of metals, spatial transcriptomics, and histological structures in colorectal cancer ». Cancer Research 84, n^o 6_Supplement (22 mars 2024) : 4949. http://dx.doi.org/10.1158/1538-7445.am2024-4949.

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Abstract Colorectal Cancer (CRC) accounts for nearly 10% of all cancer cases and is the second-leading cause of cancer-related deaths worldwide. The increased incidence of CRC in younger demographics underscores the need for improved screening and prognostication. These enhancements are crucial to augment staging practices which focus on accurate evaluation of local lymph node involvement and distant metastasis. Essential trace elements such as copper and iron within the tumor microenvironment (TME) present novel therapeutic strategies- e.g., copper in cell proliferation/signaling and iron in pro-tumorigenic pathways, amongst other multifaceted roles. Despite advancements in spatial imaging/sequencing for detailed mapping of elemental abundance and gene expression profiles at near-subcellular resolution, the understanding of metal signaling and transport pathways in tumors is limited. This gap highlights the need for sophisticated informatics software for data integration and analysis. We developed a computational workflow for spatial multimodal analysis of elements, genes, cell-types, and histological features, applied to a unique CRC case (pT3) as proof-of-concept. Elemental imaging at 5-micron resolution was performed using laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICPTOF-MS). The 10x Genomics Visium spatial transcriptomic (ST) CytAssist assay captured spatial variation in gene expression within 55-micron spots, with 40X H&E-stained whole slide imaging (Leica Aperio GT450). Cell type proportions within spots were determined through integration of single cell RNASeq. Regions within, around and away from tumor were annotated by a pathologist. ST and LA-ICPTOF-MS were integrated through co-registration software developed at Biomedical National Elemental Imaging Resource. Local Getis-Ord spatial statistics defined hotspots with high elemental concentration. Wilcoxon tests were used to perform differential expression analysis based on metal hotspots, followed by identification of associated biological pathways through Enrichr with Bonferroni adjustment. Preliminary findings revealed distinct trace element distributions in the TME. For instance, Copper was localized within tumor, correlating with pathways related to immune response and activation (overlap=10/89, p<0.0001). Iron was found concentrated at the proliferative front of the tumor, associated with the epithelial to mesenchymal transition pathway and extracellular matrix remodeling (overlap=25/291, p<0.0001), as well as with a mesenchymal phenotype (W=11.7, p<0.0001), identified through cell type deconvolution. Future work will expand on these findings across multiple tissue contexts as means to capture biological processes governing tumor metastasis, recurrence and survival for biomarker discovery and therapeutics development. Citation Format: Aruesha Srivastava, Neha Shaik, Yunrui Lu, Matthew Chan, Alos Diallo, Serin Han, Ramsey Steiner, Tracy Punshon, Brian Jackson, Linda Vahdat, Louis Vaickus, Jack Hoopes, Fred Kolling, Jonathan Marotti, Joshua Levy. Multimodal analysis of metals, spatial transcriptomics, and histological structures in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4949.

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Ferreira da Cruz, Taniel, Geilson Rodrigues da Silva, Hygor Rodrigues de Oliveira et Lucas Pereira Gandra. « DETERMINAÇÃO DO TEOR DE METAIS PESADOS EM ALFACES CULTIVADAS NAS HORTAS URBANAS NA CIDADE DE COXIM-MS ». UNESUM-Ciencias. Revista Científica Multidisciplinaria. ISSN 2602-8166 2, n^o 2 (26 septembre 2018) : 25–34. http://dx.doi.org/10.47230/unesum-ciencias.v2.n2.2018.76.

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RESUMOA alface trata-se de uma hortaliça inicialmente cultivada no continente asiático, e encontra-se já disseminada por todas as regiões do Brasil. Entretanto uma das problemáticas relacionada ao consumo desta hortaliça é o uso de defensivos agrícolas durante seu cultivo, podendo provocar a contaminação por metais pesados. Sendo assim, o presente trabalho teve como objetivo realizar a análise dos teores dos metais Cu, Fe, Ni, Cd, Pb e Co em alfaces cultivadas em hortas urbanas na região de Coxim-MS. Para isso, utilizou-se a técnica de espectrometria de absorção atômica em chama e compararam-se os resultados com os valores máximos estipulados pelas legislações para alimentos. Coletaram-se três amostras do tipo alface americana em culturas convencionais. Para a preparação das amostras, utilizou-se digestor de microondas, e posteriormente preparou-se padrões de calibração para leitura no espectrofotômetro. Verificou-se que os elementos cobre e níquel estão abaixo dos valores máximos permitidos pela legislação de alimentos. Já em relação ao ferro e o cobalto não há normativas específicas para esses metais em hortaliças, sendo que o cobalto está abaixo do limite de detecção, assim como, o chumbo. Por sua vez o cádmio apresentou em um dos pontos, intervalo estatístico acima do valor máximo permitido. Sendo assim evidenciou-se a ausência de contaminação por metais pesados nas hortas urbanas que abastecem dos consumidores da cidade. PALAVRAS CHAVE: Análise de Alimentos; Legislações para alimentos; Espectrofotometria de Absorção Atômica em Chama. DETERMINATION OF THE HEAVY METAL CONTENT IN LETTUCE GROWN IN URBAN GARDENS IN THE CITY OF COXIM-MSABSTRACTLettuce is a vegetable originally grown on the Asian continent, and is already disseminated by all regions of Brazil. However one of the problems related to the consumption of this vegetable is the use of agricultural pesticides during its cultivation, and can cause the contamination by heavy metals. Thus, the present work was intended to carry out the analysis of the levels of Cu metals, Fe, Ni, Cd, Pb and Co in lettuce cultivated in urban gardens in the cushion-MS region. For this, the technique of atomic absorption spectrometry was used in flame and compared the Results with the maximum values stipulated by the food legislation. Three samples of the American lettuce type were collected in conventional cultures. For the preparation of the samples, a microwave digester was used, and subsequently the calibration patterns were prepared for reading in the spectrophotometer. It was found that the copper and nickel elements are below the maximum permitted values by food legislation. In relation to iron and cobalt there are no specific norms for these metals in greenery, and the cobalt is below the detection limit, as well as lead. In turn cadmium presented in one of the points, statistical interval above the maximum permitted value. Thus, the absence of heavy metal contamination was demonstrated in the urban gardens that supply the city's consumers.KEYWORDS: Food analysis; Food legislation; Flame Atomic Absortion Spectrometry.

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I. E., Akpan, Achadu M. Abah. et Chukwuma F. O. « Evaluation of Discharged Untreated Wastewater from Pulping and Bleaching Operations in a Bamboo Based Tissue Paper Making Plant in Nigeria ». Research and Analysis Journal 5, n^o 1 (27 janvier 2022) : 7–15. http://dx.doi.org/10.18535/raj.v5i1.273.

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This study on Evaluation of Discharged Untreated Wastewater from Pulping and Bleaching operations in a Bamboo Based tissue Paper Making Plant in Nigeria was conducted mainly to evaluate the pollutant loads present in wastewater produced during the Pulping and Bleaching operations of the tissue paper making progression. The wastewater samples were obtained and examined to find out the pollutants they contain by checking the availability of some physicochemical parameters using standard methods by American Public Health Association (APHA). The analyzed parameters obtained for the pulping and bleaching processes respectively are pH (7.42 and 4.49), EC (316µS/cm and 47µS/cm), TDS (158mg/l and 24mg/l), Turbidity (19.3NTU and 28.7NTU), Temperature (28.47°C and 28.48°C), DO (3.66mg/l and 1.93mg/l), BOD5 (74.02mg/l and 62.00mg/l), COD (140.30mg/l and 120.40mg/l), TOC (10.3% and 7.1%), THB (1.60x103cfu/ml and 7.40x104cfu/ml), THF (0cfu/ml and 2.30x103cfu/ml) and heavy metals like Hg (<0.001mg/l and <0.001mg/l), Pb (0.281mg/l and 0.273mg/l), Ni (0.115mg/l and 0.117mg/l), Co (0.193mg/l and 0.208mg/l) and As (<0.001mg/l and <0.001mg/l). These results were also compared amid the permissible regulatory standards set by the FMEnv and NESREA. From the comparative analysis, the bleaching wastewater sample was more polluted than that from pulping. EC, TDS, BOD5, COD, TOC and Pb were higher in the pulping wastewater sample which could be attributed to the organic nature of the starting material; bamboo and residues of the pulping agents; caustic soda and ammonia while Acidity, Turbidity, Temperature, DO, Ni, Co, THB and TF were higher in the bleaching wastewater sample and could be caused by the bleaching agents and the availability of microorganisms. The result showed that some parameters except BOD5, turbidity, COD, DO and pH from pulping fell within regulatory limit. This could be linked to the virgin fibre from bamboo applied which contains less pollutant compared to other industries using waste papers from different sources.

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Woolford, Andrew, Wanda June et Sereyvothny Um. « “We Planted Rice and Killed People:” Symbiogenetic Destruction in the Cambodian Genocide ». Genocide Studies and Prevention 15, n^o 1 (mai 2021) : 44–67. http://dx.doi.org/10.5038/1911-9933.15.1.1805.

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In recent years, genocide scholars have given greater attention to the dangers posed by climate change for increasing the prevalence or intensity of genocide. Challenges related to forced migration, resource scarcity, famine, and other threats of the Anthropocene are identified as sources of present and future risk, especially for those committed to genocide prevention. We approach the connection between the natural and social aspects of genocide from a different angle. Our research emanates out of a North American Indigenous studies and new materialist rather than Euro-genocide studies framework, meaning we see the natural and the social (or cultural) as inseparable, deeply imbricated, phenomena. We argue that those entities designated natural are often engaged in co-constitutive relations with the social and cultural groups that are the focus of genocide studies. Simply put, groups become what they are through interaction—or symbiogenesis—with their natural world(s). Symbiogenetic destruction, then, is the destruction of this symbiogenesis. We use this term to draw attention to how relations with more-than-human entities are integral components of the ongoing formation of group life, and how they are put at risk by genocide. In particular, we examine testimony that centers on the relationship between Khmer people and rice, including rice cultivation and consumption, as it was impacted by the Khmer Rouge. In so doing, we highlight the cultural consequences of social/natural death in the Cambodian genocide.

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Takar, A. A., D. N. Roy et D. L. McLaughlin. « Chemical changes in the stem matrix of three tree species exposed to fluoride emissions from an aluminum smelter ». Forestry Chronicle 74, n^o 1 (1 février 1998) : 78–82. http://dx.doi.org/10.5558/tfc74078-1.

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The principal objective of this study was to investigate the major organic and trace elemental composition of the stem tissues of three tree species of a mixed forest on Cornwall Island in the St. Lawrence River, Ontario. This forest was exposed to atmospheric hydrogen fluoride (HF) at levels > 71 μg F/m3/24 h from an aluminum smelter (Reynolds Metals Co. Ltd.) for twenty years, followed by fourteen years of reduced emissions (< 40 μg F/m3/24 h), which is still greater than the current Ontario air quality criterion for HF (0.36 μg F/m3/24 h). Increment cores were collected at breast height from white pine, red oak, and American beech from the study woodlot on Cornwall Island and at a control site in Long Sault Provincial Park.Tree-rings were analyzed for eight elements (fluorine, aluminum, manganese, magnesium, calcium, sodium, chlorine and potassium) and some major organic compounds (total extractives, lignin and holocellulose). All three species from the study woodlot showed significant chemical compositional changes during the peak pollution and post-abatement periods. There was a substantial increase of the levels of total extractives (up to 167%), lignin (up to 38%), fluorine, aluminum and manganese and a significant decrease of holocellulose content (up to 17%) in the stem tissues during the period of HF exposure, compared to the pre-pollution period. In contrast, trees from the control site showed no significant change in chemical composition in any of the three periods. Lower cellulose and higher lignin and extractives concentrations potentially makes the wood weaker and less suitable for dimension lumber and pulping. Key words: hydrogen fluoride, extractives, lignin, holocellulose, trace elements

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Haq, Naeem Ul, Hayat Mohammad Khan, Musawer Khan, Mohammad Ishaq, Muhammad Usman et Gohar Ali. « Clinical Features and Surgical Management of Intracranial Meningioma’s in the Elderly ». Scholars Journal of Applied Medical Sciences 10, n^o 7 (23 juillet 2022) : 1105–12. http://dx.doi.org/10.36347/sjams.2022.v10i07.011.

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Objective: Given the threat related with surgical intervention of intracranial meningiomas in the older population because of maturing physiology and numerous co morbidities, an endeavor was made to distinguish mediators impacting results and to characterize a category of individuals who ought not be surgically treated because of deprived prognosis. Study Setting: The study was conducted in neurosurgery unit mardan medical complex / bacha khan medical college Name of Hospital, Pakistan. Methods: The investigation of 58 individuals over the age of 70 years was conducted to determine short- and long-term results. Additionally, we derived scores for our patients using the previously reported CRGS, SKALE, and GSS grading systems. Result: As per the SKALE reviewing framework, neurological grimness was exclusively associated with a crucial site (P=0.02). Six people (10.3 percent) capitulated to their wounds. The Karnofsky score (KPS 60 versus KPS 70; P=0.0162), the American Society scale status (ASA 1 or 2 versus ASA 3; P=0.0022), and the evaluation of meningioma’s were totally connected with mortality (P=0.012). The WHO grade (P=0.00048) and Simpson evaluation of resection (P=0.0437) were related with tumor repetition in six cases. Except for patients who died because of medical procedure or reoccurrence (15.5%), majority of subjects improved (50%) or remain unaltered (25.9%) in contrast with their karnofsky score before surgery. Conclusion: Neurological impairment following surgery was only observed in patients with a significant tumor placement (skull base, eloquent area, large vessels indulgence by the tumor). Because of the greatly increased threat of fatality, surgery should be carefully considered in individuals with a low functional state (KPS 60) or a bad bodily state (ASA 3 status). During routine visits, the majority of patients’ neurological health enhanced or remains constant in comparison to their condition before operation.

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Hum, Nicholas R., John M. Rolison, Nicole F. Leon, Ali Navid, Aimy Sebastian, Josh Wimpenny et Gabriela Loots. « Abstract 6850 : Unraveling molecular factors contributing to metallomic dyshomeostasis induced by triple-negative breast cancer using single-cell RNA sequencing ». Cancer Research 84, n^o 6_Supplement (22 mars 2024) : 6850. http://dx.doi.org/10.1158/1538-7445.am2024-6850.

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Abstract Triple-negative breast cancer (TNBC) comprises 20% of breast cancer cases and exhibits an aggressive phenotype with increased metastasis; these patients have limited treatment options, poorer prognosis and higher mortality than other breast cancers (BC). Metallomics is a relatively new discipline that studies the abundance of metal ions in biological samples. Metallomic analysis has identified differences in BC patients in elements such as iron (Fe) and zinc (Zn) but it is unclear if these reflect metabolic changes in the tumor. In this study, we conducted metallomic profiling to characterize 55 trace elements in the circulation and in the tumor microenvironment of orthotopic mammary fat pad tumors from two isogenic BC cell lines (highly metastatic 4T1; nonmetastatic 67NR). We complemented this analysis with single-cell RNA sequencing of the tumor to determine if complementary changes occur in molecules known to utilize metals as co-factors or transporters and identify drivers of metal metabolism in different tumors. We performed analysis on systemic metal elements by examining whole blood (including blood cells and platelets) and plasma separately. Tumor samples were assessed at the whole tissue level, and we also profiled separated immune or non-immune cells from the tumor. Li, Na, Mg, P, S, K, Ca, Fe, Cu, Zn, Rb were detectable within 100ul of input of whole blood or plasma. Metallomic analysis of the tumor and associated cell populations detected differential levels of Na, Mg, P, S, K Ca, Fe, Zn, and Rb from an average of 200mg of tissue or 2 million cells. Based on scRNAseq analysis, 67NR tumors were composed of greater proportions of cancer cells relative to the 4T1 tumors (79.1% vs 58.8% of tumor cells respectively) and endothelial cells (2.5% vs 1.8%). 4T1 tumors contained an increased abundance of cancer-associated fibroblasts (5.6% vs 2.1%) as well as immune infiltration (33.8% vs 16.3%). Fibroblasts and macrophage populations also showed elevated metal transporter expression levels based on gene expression relative to other tumor residing cell types yet minor differences induced by cancer type. Cancer cells express high levels of metal transport genes (Zn, Ca, Co, Na, Mg, Fe). 67NR cancer cells exhibited increased gene expression of many metal-transporting proteins including numerous solute carrier (SLC) group of membrane transport proteins such as Slc41a2 when compared to the more aggressive 4T1 cells. This study underscores the potential of linking metallomic profiling to tumor composition and cancer behaviors, offering a pathway for identifying novel biomarkers to differentiate aggressive and non-aggressive forms of breast cancer. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Citation Format: Nicholas R. Hum, John M. Rolison, Nicole F. Leon, Ali Navid, Aimy Sebastian, Josh Wimpenny, Gabriela Loots. Unraveling molecular factors contributing to metallomic dyshomeostasis induced by triple-negative breast cancer using single-cell RNA sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6850.

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Luo, Fang, Luca Silvioli, David A. Cullen, Andrea Zitolo, Frederic Jaouen et Peter Strasser. « A New Catalyst System for the Oxygen Reduction Reaction (ORR) at Fuel Cell Cathodes : P-Block Precious Group Metal-Free Tin and Nitrogen-Doped Carbon (SnNC) Catalyst ». ECS Meeting Abstracts MA2023-02, n^o 40 (22 décembre 2023) : 1943. http://dx.doi.org/10.1149/ma2023-02401943mtgabs.

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The sluggish kinetics of the Oxygen Reduction Reaction (ORR) and the consequently large amount of platinum catalyst required for cathode material in Proton Exchange Membrane Fuel Cell (PEMFC) is today’s primary hurdle for commercializing fuel cell technology in automotive application.1 A class of carbon-doped with metal and nitrogen electrocatalysts (labelled MNC) is promising substitute for platinum-group metals (PGMs) in oxygen reduction reaction (ORR) in PEMFC.2 Particular attention was placed on a specific family of MNC catalysts derived from 3d transition metal precursors with FeNC and CoNC being the most promising for PEMFC applications requiring high power density.3-5 In the present contribution, we report on a new MNC catalyst system, different by its chemical nature from all others catalysts previously reported as ORR-active in acidic medium. The highlights of this work are the successful design and synthesis of SnNC as a non-noble metal catalyst for the first time, and the finding that SnNC hosts Sn-based active sites that can achieve the same turnover frequency as Fe-based active sites in FeNC, and much higher turnover frequency than Co-based active sites in CoNC. FeNC and CoNC materials have, until now, been the state-of-art PGM-free catalysts for ORR in acidic medium. The present SnNC material shows also high and similar selectivity for the four-electron ORR pathway as FeNC, much higher than CoNC materials. The prepared SnNC catalysts meet and exceed the FeNC catalysts in terms of hydrogen-air fuel cell power density. The SnNC-NH3 catalysts displayed a 40-50% higher current density than FeNC-NH3 at cell voltages below 0.7 V. Added benefits include a Fenton-inactive character of Sn. Among other techniques, density functional theory and 119Sn Mössbauer spectroscopy were used in combination to investigate SnNC, providing for the first time insights on the structure of its active sites, their rate-determining step for ORR and selectivity for the four-electron reduction pathway. References Holton, O. T.; Stevenson, J. W., The Role of Platinum in Proton Exchange Membrane Fuel Cells. Platinum Metals Review 2013, 57 (4), 259-271. Luo, F.; Wagner, S.; Ju, W.; Primbs, M.; Li, S.; Wang, H.; Kramm, U. I.; Strasser, P., Kinetic Diagnostics and Synthetic Design of Platinum Group Metal-Free Electrocatalysts for the Oxygen Reduction Reaction Using Reactivity Maps and Site Utilization Descriptors. Journal of the American Chemical Society 2022, 144 (30), 13487-13498. Zitolo, A.; Ranjbar-Sahraie, N.; Mineva, T.; Li, J.; Jia, Q.; Stamatin, S.; Harrington, G. F.; Lyth, S. M.; Krtil, P.; Mukerjee, S.; Fonda, E.; Jaouen, F., Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction. Nature Communications 2017, 8 (1), 957. Zitolo, A.; Goellner, V.; Armel, V.; Sougrati, M.-T.; Mineva, T.; Stievano, L.; Fonda, E.; Jaouen, F., Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nature materials 2015, 14 (9), 937-942. Luo, F.; Roy, A.; Silvioli, L.; Cullen, D. A.; Zitolo, A.; Sougrati, M. T.; Oguz, I. C.; Mineva, T.; Teschner, D.; Wagner, S.; Wen, J.; Dionigi, F.; Kramm, U. I.; Rossmeisl, J.; Jaouen, F.; Strasser, P., P-block single-metal-site tin/nitrogen-doped carbon fuel cell cathode catalyst for oxygen reduction reaction. Nature materials 2020, 19 (11), 1215-1223.

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Milidragovic, Dejan, Graham T. Nixon, James S. Scoates, James A. Nott et Dylan W. Spence. « Redox-controlled chalcophile element geochemistry of the Polaris Alaskan-type mafic-ultramafic complex, British Columbia, Canada ». Canadian Mineralogist 59, n^o 6 (1 novembre 2021) : 1627–60. http://dx.doi.org/10.3749/canmin.2100006.

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ABSTRACT The Early Jurassic Polaris Alaskan-type intrusion in the Quesnel accreted arc terrane of the North American Cordillera is a zoned, mafic-ultramafic intrusive body that contains two main styles of magmatic mineralization of petrologic and potential economic significance: (1) chromitite-associated platinum group element (PGE) mineralization hosted by dunite (±wehrlite); and (2) sulfide-associated Cu-PGE-Au mineralization hosted by olivine (±magnetite) clinopyroxenite, hornblendite, and gabbro-diorite. Dunite-hosted PGE mineralization is spatially associated with thin discontinuous layers and schlieren of chromitite and chromitiferous dunite and is characterized by marked enrichments in iridium-subgroup PGE (IPGE) relative to palladium-subgroup PGE (PPGE). Discrete grains of platinum group minerals (PGM) are exceedingly rare, and the bulk of the PGE are inferred to reside in solid solution within chromite±olivine. The absence of Pt-Fe alloys in dunite of the Polaris intrusion is atypical, as Pt-enrichment of dunite-hosted chromitite is widely regarded as a characteristic feature of Alaskan-type intrusions. This discrepancy appears to be consistent with the strong positive dependence of Pt solubility on the oxidation state of sulfide-undersaturated magmas. Through comparison with experimentally determined PGE solubilities, we infer that the earliest (highest temperature) olivine-chromite cumulates of the Polaris intrusion crystallized from a strongly oxidized ultramafic parental magma with an estimated log f(O2) > FMQ+2. Parental magmas with oxygen fugacities more typical of volcanic arc settings [log f(O2) ∼ FMQ to ∼ FMQ+2] are, in turn, considered more favorable for co-precipitation of Pt-Fe alloys with olivine and chromite. More evolved clinopyroxene- and hornblende-rich cumulates of the Polaris intrusion contain low abundances of disseminated magmatic sulfides, consisting of pyrrhotite and chalcopyrite with minor pentlandite, pyrite, and rare bornite (≤12 wt.% total sulfides), which occur interstitially or as polyphase inclusions in silicates and oxides. The sulfide-bearing rocks are characterized by strong primitive mantle-normalized depletions in IPGE and enrichments in Cu-PPGE-Au, patterns that resemble those of other Alaskan-type intrusions and primitive arc lavas. The absolute abundances and sulfur-normalized whole-rock concentrations (Ci/S, serving as proxy for sulfide metal tenor) of chalcophile elements, including Cu/S, in sulfide-bearing rocks are highest in olivine clinopyroxenite. Sulfide saturation in the relatively evolved magmas of the Polaris intrusion, and Alaskan-type intrusions in general, appears to be intimately tied to the appearance of magnetite. Fractional crystallization of magnetite during the formation of olivine clinopyroxenite at Polaris resulted in reduction of the residual magma to log f(O2) ≤ FMQ+2, leading to segregation of an immiscible sulfide melt with high Cu/Fe and Cu/S, and high PGE and Au tenors. Continued fractionation resulted in sulfide melts that were progressively more depleted in precious and base chalcophile metals. The two styles of PGE mineralization in the Polaris Alaskan-type intrusion are interpreted to reflect the evolution of strongly oxidized, hydrous ultramafic parental magma(s) through intrinsic magmatic fractionation processes that potentially promote sulfide saturation in the absence of wallrock assimilation.

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Hung, Tran Trong, Tran Anh Tu, Dang Thuong Huyen et Marc Desmet. « Presence of trace elements in sediment of Can Gio mangrove forest, Ho Chi Minh city, Vietnam ». VIETNAM JOURNAL OF EARTH SCIENCES 41, n^o 1 (8 janvier 2019) : 21–35. http://dx.doi.org/10.15625/0866-7187/41/1/13543.

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Can Gio mangrove forest (CGM) is located downstream of Ho Chi Minh City (HCMC), situated between an estuarine system of Dong Nai - Sai Gon river and a part of Vam Co river. The CGM is the largest restored mangrove forest in Vietnam and the UNESCO’s Mangrove Biosphere Reserve. The CGM has been gradually facing to numeric challenges of global climate change, environmental degradation and socio-economic development for the last decades. To evaluate sediment quality in the CGM, we collected 13 cores to analyze for sediment grain size, organic matter content, and trace element concentration of Cd, Cr, Cu, Ni, Pb, Zn. Results showed that trace element concentrations ranged from uncontaminated (Cd, Cu, and Zn) to very minor contaminated (Cr, Ni, and Pb). The concentrations were gradually influenced by suspended particle size and the mangrove plants.ReferencesAnh M.T., Chi D.H., Vinh N.N., Loan T.T., Triet L.M., Slootenb K.B.-V., Tarradellas J., 2003. Micropollutants in the sediment of Sai Gon – Dong Nai rivers: Situation and ecological risks. Chimia International Journal for Chemistry, 57, 09(0009–4293), 537–541.Baruddin N.A., Shazili N.A., Pradit S., 2017. Sequential extraction analysis of heavy metals in relation to bioaccumulation in mangroves, Rhizophora mucronata from Kelantan delta, Malaysia. AACL Bioflux, 10(2), 172-181. Retrieved from www.bioflux.com/aacl.Bravard J.-P., Goichot M., Tronchere H., 2014. An assessment of sediment transport processes in the lower Mekong river based on deposit grain size, the CM technique and flow energy data. Geomorphology, 207, 174-189.Cang L.T., Thanh N.C. 2008. Importing and exporting sediment to and from mangrove forest at Dong Trang estuary, Can Gio district, Ho Chi Minh city. Science & Technology Development, 11(04), 12-18.Carignan J., Hild P., Mevelle G., Morel J., Yeghicheyan D., 2001. Routine analyses of trace elements in geological samples using flow injection and low-pressure on-line liquid chromatography coupled to ICP-MS: A study of geochemical reference materials BR, DR-N, UB-N, AN-G and GH. The Journal of Geo standard and Geoanalysis, 187-198.Carlson P.R., Yarbro L.A., Zimmermann C.F., Montgomery J.R., 1983. Pore water chemistry of an overwash mangrove island. Academy Symposium: Future of the Indian River System, 46(3/4), 239-249. https://www.jstor.org/stable/24320336.Chatterjee M., Canário J., Sarkar S.K., Branco V., Godhantaraman N., Bhattacharya B.D., Bhattacharya A., 2012. Biogeochemistry of mercury and methylmercury in sediment cores from Sundarban mangrove wetland, India—a UNESCO World Heritage Site. Environ Monit Assess, 184, 5239–5254.Claudia R., Huy N.V., 2004. Water allocation policies for the Dong Nai river basin in Viet Nam: An integrated perspective. EPTD Discussion Paper, 127, 01-52.Folk R.L., Ward W.C., 1957. Brazos River bar: A study in the significance of grain size parameters. Journal of Sedimentary Petrology, 27(1), 3-26.Furukawaa K., Wolanski E., Mueller H., 1997. Currents and sediment transport in mangrove forests. Estuarine, Coastal and Shelf Science, 44, 301-310.Hai H.Q., Tuyen N.N., 2011. Coastal Erosion of Can Gio district Ho Chi Minh City due to the global climate change. The journal of development of technology and science, 14, 17-28.HCM SO S.O., 2015. Annual statistic data in 2015 for HCM city. Ho Chi Minh city: Statistic office of HCM city.HCMC, 2017. Decision No. 3901 on approving the areas of forest and land in HCM city in 2016. Ho Chi Minh: The people's committee of HCM city.Herut B., Sandler A., 2006. Normalization methods for pollutants in marine sediments: review and recommendations for the Mediterranean. Haifa 31080: Israel Oceanographic & Limnological Research: IOLR Report H18/2006.Hong P.N., San H.T., 1993. Mangroves of Vietnam: Chapter VI Human impacts on the mangrove ecosystem. Bangkok 10501: IUCN - The International Union for Conservation of Nature, ISBN: 2-8317-0166-x.Hubner R., Astin K.B., Herbert R.J., 2009. Comparison of sediment quality guidelines (SQGs) for the assessment of metal contamination in marine and estuarine environments. Journal of Environmental Monitoring, 11, 713–722.IAEA, 2003. Collection and preparation of bottom sediment samples for analysis of radionuclides and trace elements. Vienna, Austria: International Atomic Energy Agency, IAEA-TECDOC-1360, ISBN 92–0–109003–X.Jingchun L., Chongling Y., Ruifeng Z., Haoliang L., Guangqiu Q., 2008. Speciation changes of Cd in mangrove (Kandelia Candel L.) rhizosphere sediments. Bull Environ Contam Toxicol, 231-236. Doi:10.1007/s00128-007-9351-z.Kalaivanan R., Jayaprakash M., Nethaji S., Arya V., Giridharan L., 2017. Geochemistry of Core Sediments from Tropical Mangrove Region of Tamil Nadu: Implications on Trace Metals. Journal of Earth Science & Climatic Change, ISSN: 2157-7617., 8(1.1000385), 1-10. Doi:10.4172/2157-7617.1000385.Kathiresan K., Saravanakumar K., Mullai P., 2014. Bioaccumulation of trace elements by Avicennia marina. Journal of Coastal Life Medicine, 2(11), 888-894.Kitazawa T., Nakagawa T., Hashimoto T., Tateishi M., 2006. Stratigraphy and optically stimulated luminescence (OSL) dating of a Quaternary sequence along the Dong Nai River, southern Vietnam. Journal of Asian Earth Sciences, 27, 788–804.Lacerda L.D., 1998. Trace metals of biogeochemistry and diffuse pollution in mangrove (M. Vannucci, Ed.) Mangrove ecosystem occassional papers (ISSN: 0919-1348), 2, 1-72.Laura H., Probsta A., Probsta J.L., Ulrich E., 2003. Heavy metal distribution in some French forest soils: evidence for atmospheric contamination. The Science of Total Environment, 195-210.Li R., Li R., Chai M., Shen X., Xu H., Qiu G., 2015. 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« 3M Co., Abrasive Systems Div. » Metal Finishing 97, n^o 6 (juin 1999) : 75–76. http://dx.doi.org/10.1016/s0026-0576(00)83861-1.

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« American Ultraviolet Co. » Metal Finishing 97, n^o 9 (septembre 1999) : 18. http://dx.doi.org/10.1016/s0026-0576(01)80213-0.

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« American Ultraviolet Co. » Metal Finishing 103 (septembre 2005) : 1. http://dx.doi.org/10.1016/s0026-0576(05)80633-6.

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