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1.
Environ Res ; 252(Pt 3): 118953, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38636643

RESUMO

Gas separation membranes are critical in a variety of environmental research and industrial applications. These membranes are designed to selectively allow some gases to flow while blocking others, allowing for the separation and purification of gases for a variety of applications. Therefore, the demand for fast and energy-efficient gas separation techniques is of central interest for many chemical and energy production diligences due to the intensified levels of greenhouse and industrial gases. This encourages the researchers to innovate techniques for capturing and separating these gases, including membrane separation techniques. Polymeric membranes play a significant role in gas separations by capturing gases from the fuel combustion process, purifying chemical raw material used for plastic production, and isolating pure and noncombustible gases. Polyurethane-based membrane technology offers an excellent knack for gas separation applications and has also been considered more energy-efficient than conventional phase change separation methodologies. This review article reveals a thorough delineation of the current developments and efforts made for PU membranes. It further explains its uses for the separation of valuable gases such as carbon dioxide (CO2), hydrogen (H2), nitrogen (N2), methane (CH4), or a mixture of gases from a variety of gas spillages. Polyurethane (PU) is an excellent choice of material and a leading candidate for producing gas-separating membranes because of its outstanding chemical chemistry, good mechanical abilities, higher permeability, and variable microstructure. The presence of PU improves several characteristics of gas-separating membranes. Selectivity and separation efficiency of PU-centered membranes are enhanced through modifications such as blending with other polymers, use of nanoparticles (silica, metal oxides, alumina, zeolite), and interpenetrating polymer networks (IPNs) formation. This manuscript critically analyzes the various gas transport methods and selection criteria for the fabrication of PU membranes. It also covers the challenges facing the development of PU-membrane-based separation procedures.


Assuntos
Gases , Membranas Artificiais , Poliuretanos , Poliuretanos/química , Gases/química , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/química
2.
Int J Biol Macromol ; 166: 297-321, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33127548

RESUMO

Petrochemical plastics have become a cause of pollution for decades and finding alternative plastics that are environmental friendly. Polyhydroxyalkanoate (PHA), a biopolyester produced by microbial cells, has characteristics (biocompatible, biodegradable, non-toxic) that make it appropriate as a biodegradable plastic substance. The different forms of PHA make it suitable to a wide choice of products, from packaging materials to biomedical applications. The major challenge in commercialization of PHA is the cost of manufacturing. There are a lot of factors that could affect the efficiency of a development method. The development of new strategic parameters for better synthesis, including consumption of low cost carbon substrates, genetic modification of PHA-producing strains, and fermentational strategies are discussed. Recently, many efforts have been made to develop a method for the cost-effective production of PHAs. The isolation, analysis as well as characterization of PHAs are significant factors for any developmental process. Due to the biodegradable and biocompatible properties of PHAs, they are majorly used in biomedical applications such as vascular grafting, heart tissue engineering, skin tissue repairing, liver tissue engineering, nerve tissue engineering, bone tissue engineering, cartilage tissue engineering and therapeutic carrier. The emerging and interesting area of research is the development of self-healing biopolymer that could significantly broaden the operational life and protection of the polymeric materials for a broad range of uses. Biodegradable and biocompatible polymers are considered as the green materials in place of petroleum-based plastics in the future.


Assuntos
Plásticos Biodegradáveis/química , Tecnologia Biomédica/tendências , Microbiologia Industrial/métodos , Poli-Hidroxialcanoatos/química , Plásticos Biodegradáveis/economia , Tecnologia Biomédica/economia , Desenvolvimento Econômico , Microbiologia Industrial/economia , Poli-Hidroxialcanoatos/biossíntese , Poli-Hidroxialcanoatos/economia
3.
Iran J Public Health ; 42(11): 1223-31, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26171334

RESUMO

BACKGROUND: The current study aims to measure the efficiency of primary health care units completed in health sector of rural Azad Jammu and Kashmir (AJK) and to compare it across developed and deprived regions. METHODS: Operational efficiency and beneficiary efficiency of a total of 32 Basic Health Units (BHUs) were measured through Data Envelopment Analysis (DEA) by using different input and output variables. Independent sample T-test was applied to compare these efficiencies across developed and deprived regions. RESULTS: The study could find no significant difference of operational efficiency across developed and deprived regions, however a significant difference was found across regions from beneficiary perspective (P= 0.044). CONCLUSION: The study concludes that BHUs of deprived region are more efficient from beneficiary perspective, however there is no significant difference of operational efficiency across the regions.

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