Pcbs
Mostrando 1-12 de 135 artigos, teses e dissertações.
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1. A Design of a Compact Microwave Diplexer in Microstrip Technology Based on Bandpass Filters Using Stepped Impedance Resonator
Abstract This paper describes the design of a compact microstrip microwave diplexer based on bandpass filters and a stepped impedance resonator for 4G applications. The diplexer is composed of two band-pass filters (BPF) that operate at 1.8 and 2.5 GHz. Both bandpass filters for the receiver at 1.705-1.895 GHZ and the transmitter at 2.41-2.6 GHZ have a -3dB
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. PROCESSING OF A METAL CONCENTRATE FROM GROUND WASTE PRINTED CIRCUIT BOARDS IN ACIDIC MEDIA USING HYDROGEN PEROXIDE AS OXIDANT
The recovery of precious and base metals of a metal concentrate from ground waste printed circuit boards (PCBs) is described in detail. Samples were treated with NaOHaq. to remove the soldering mask. Experiments were performed in acidic medium (HF, H2SO4, CH3COOH or H3PO4) using H2O2 as oxidant. Base metals were leached in high yields (>99 wt.%) at ~40 ºC a
Quím. Nova. Publicado em: 20/07/2020
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3. A Selective Gas Chromatography-Selected Ion Monitoring Mass Spectrometry (GC-MS/SIM) Method to Determine Polychlorinated Biphenyls in Fuller’s Earth
Polychlorinated biphenyls (PCBs) are carcinogenic to humans and can be found in Fuller’s earth used for the regeneration of used transformer oil. This work describes a highly selective gas chromatographic-selected ion monitoring mass spectrometric method (GC-MS/SIM) for the simultaneous determination of three Aroclor PCB congener mixtures (1242, 1254, and
J. Braz. Chem. Soc.. Publicado em: 2020-03
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4. Evaluation of Mass Loss in Different Stages of Printed Circuit Boards Recycling Employed in Temperature Controllers
The aim of this work was to evaluate mass loss in each stage of the recycling process for metal recovery from PCBs of controllers and temperature indicators of cold chambers. The stages of process consists of grinding, particle size classification, magnetic and electrostatic separation. It was analyzed 13 kg of PCBs. These PCBs were crushed and ground. The g
Mat. Res.. Publicado em: 02/12/2019
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5. Níveis de bifenilos policlorados (PCBs) em leite em pó integral e ingestão diária estimada para uma população infantil
RESUMO: Os bifenilos policlorados (PCBs) são contaminantes químicos classificados como poluentes orgânicos persistentes. Embora seu uso tenha sido banido há mais de décadas, os PCBs ainda encontram-se presentes no meio ambiente e portanto, todos os organismos vivos podem estar expostos a esses compostos. A alimentação, especialmente alimentos gorduro
Cienc. Rural. Publicado em: 06/12/2018
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6. Operational conditions of an electrostatic separator for concentrate copper from electronic waste
Abstract Interest in recycling for the recovery of valuable substances, such as precious metals from electric and electronic waste has been increasing year after year due to the large amount present in such waste compared to primary sources. There is environmental concern, since the amount of this kind of waste is increasing due to rapid technological advanc
REM, Int. Eng. J.. Publicado em: 2018-07
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7. AVALIAÇÃO DOS RESÍDUOS GERADOS DURANTE A DESTRUIÇÃO DE PCBS PELO PROCESSO CATALISADO POR BASE
There are many processes capable of decontamination of polychlorinated biphenyls in several matrixes. The set of inputs, materials, operation conditions and efficiencies are wide. The base catalyzed dechlorination process shows application potential in great scale, mainly due mild chemical reaction conditions and low cost raw materials. The KPEG is a familia
Quím. Nova. Publicado em: 2018-06
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8. The legacy of man-made organic compounds in surface sediments of Pina Sound and Suape Estuary, northeastern Brazil
Resumo Bifenilas policloradas (PCBs) e pesticidas organoclorados (OCPs) são compostos orgânicos sintéticos que causam efeitos negativos em organismos aquáticos, eventualmente alterando o funcionamento de ecossistemas com consequências locais para o ciclo do carbono. O presente estudo investigou PCBs e OCPs em sedimentos superficiais de dois estuários c
Braz. j. oceanogr.. Publicado em: 2018-03
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9. PCDD/Fs and PCBs in Soils: a Study of Case in the City of Belo Horizonte-MG
Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs)) are substances that represent a global concern due to their ubiquitous presence and toxicity. Industrial processes and other human activities as well as uncontrollable accidents are the main sources that release these pollutants into t
J. Braz. Chem. Soc.. Publicado em: 2017-05
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10. Solid-Liquid Extraction with Low Temperature Purification Coupled with Gas Chromatography and Mass Spectrometry for Determination of Polychlorinated Biphenyls in Sewage Sludge
Sewage sludge is the residue produced by the wastewater treatment plants, which can be used as soil conditioner in agriculture. However, the current legislation recommends monitoring chemical contaminants such as polychlorinated biphenyls (PCBs). In this study, solid-liquid extraction with low temperature purification (SLE-LTP) was optimized and validated fo
J. Braz. Chem. Soc.. Publicado em: 2017-01
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11. An Enhanced Random Vibration and Fatigue Model for Printed Circuit Boards
Abstract Aerospace vehicles are mostly exposed to random vibration loads during its operational lifetime. These harsh conditions excites vibration responses in the vehicles printed circuit boards, what can cause failure on mission functionality due to fatigue damage of electronic components. A novel analytical model to evaluate the useful life of embedded el
Lat. Am. j. solids struct.. Publicado em: 2017
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12. Regional analysis of potential polychlorinated biphenyl degrading bacterial strains from China
ABSTRACT Polychlorinated biphenyls (PCBs), the chlorinated derivatives of biphenyl, are one of the most prevalent, highly toxic and persistent groups of contaminants in the environment. The objective of this study was to investigate the biodegradation of PCBs in northeastern (Heilongjiang Province), northern (Shanxi Province) and eastern China (Shanghai muni
Braz. J. Microbiol.. Publicado em: 2016-09