276 research outputs found
The rate-based modelling of CO2 removal from the flue gases of power plants
No full textRecently global warming has become a topic of great interest, involving social, economic and industrial issues. Many efforts are being made in order to limit emissions of CO2, a powerful greenhouse gas, whose massive presence in the atmosphere is increasing more and more. Industrially the most commonly used process for CO2 capture is absorption by alkanolamines, widely applied to the removal of exhaust gases from power plants. The design of the absorber is still difficult, due to the different phenomena involved. Commercially, several process simulators can be found, based on different assumptions, both for thermodynamics and for diffusion with reaction. Thermodynamics, kinetics and mass transfer greatly influence the chemical absorption process. Acid gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, usually with a / method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” or the “rate-based” one. This latter, if based on a proper mass transfer theory, can be used to correctly describe the phenomenon of diffusion with reaction occurring from the vapor phase to the liquid phase.
This paper focuses on modelling the absorption of CO2 by means of a piperazine solution, performed by properly modifying ASPEN Plus® with a homemade subroutine linked to the simulator. Experimental data of a pilot plant for cleaning flue gases from power plants have been used to validate the model, which well represents the absorption phenomeno
Comparison between Cyrene and NMP as Solvents for CO2 Removal
No full textN-Methyl-2-Pyrrolidone (NMP) is one of the most used solvents for CO2 removal from gaseous streams by physical absorption and, recently, it has also been considered as a component of hybrid solvents performing both physical and chemical absorption for possible applications to the capture of CO2 from flue gas streams. However, NMP has some drawbacks and it has been included in the list of ‘Substances of Very High Concern’ according to the European Regulation No. 1907/2006. For this reason, alternative solvents are being considered. Cyrene is a biodegradable, non-mutagenic, non-toxic and biomass-derived solvent, having similar characteristics to NMP. The main similarity between the two species consists in the fact that they result to be dipolar aprotic solvents, as proved by the values of both Kamlet–Abboud–Taft and Hansen space parameters. Despite that, NMP and Cyrene differ in physical properties as boiling point, flash point, autoignition temperature and water solubility. However, to the authors’ knowledge, no comparison is available in the literature regarding the solubility of CO2, which is a key parameter for defining the suitability of a solvent for CO2 removal. In the context of the PRIN 2022 project “GREEN-based water-lean SOLvent for CO2 capture” (GREENSOL), funded by the European Union – NextGenerationEU, a detailed analysis of all the CO2 solubility data available in the literature is presented in this work in order to determine whether Cyrene can be used as a bio-based alternative to NMP as solvent for physical absorption
Valutazione PED di un insieme articolato: l’“ISOTHERM PWR” (Recuperatore energetico da rifiuti speciali e tossico nocivi)
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Small-sized newborn dogs skeletal development: radiologic, morphometric, and histological findings obtained from spontaneously dead animals
No full textBackground: Very little is known about neonatal skeletal development in small-sized purebred dogs. In order to
improve this knowledge, 27 spontaneously dead puppies belonging to small-sized breeds were enrolled in this
study for radiologic, histological and morphometric investigations.
Results: The appearance of the limb secondary ossification centers and the onset of their formation were clearly
observed by x rays and confirmed by histological evidences. Radiographic and anatomic measurements of limb
bones length and skull length and width were positively correlated with body weight and age of the subjects and
the body weight was positively correlated with radius bone mineral density, as demonstrated by dual-energy x-rays
absorptiometry.
Conclusions: These data provided original information on the growth of newborn small-sized breed dogs, and
suggest that cadavers may be useful to study skeletal development
Asymptomatic unilateral ovarian leiomyoma in a german shepherd bitch
No full textThis report shows for the first time clinical imaging (ultrasound and computed tomography), histological and immunohistochemical findings of an ovarian leiomyoma, coincidentally diagnosed in an asymptomatic unmated nulliparous ten year-old German shepherd bitch concurrently suffering from multiple mammary tumors. A thorough examination allowed the differentiation of ovarian leiomyoma from other spindle cell tumors. An accurate description of the diagnostic procedures useful in the managing of ovarian leiomyoma could provide valuable information to veterinary practitioners. Indeed, despite its rarity and nonspecific symptoms, ovarian leiomyoma may also affect the dog with an unknown potential risk
Incontinentia pigmenti : case report
No full textIP is an uncommon X-linked dominant disorder (incidence: 1/40.000 newborn). It is caused by mutations in NEMO. It is characterized by cutaneous lesions and dental, ocular, neurologic, nails, hair disorders. The ocular and neurologic sequelae represent the major morbidity in IP. We present a case-report with classical cutaneous features diagnostic for IP. The clinical, ophtalomologic and neurologic examinations revealed no other pathological manifestation
Proposal for a protocol for the staging of incontinentia pigmenti in pediatric age
No full textIncontinentia Pigmenti (IP) is an X-linked dominant disorder of skin with neurologic and ophthalmologic involvement. IP predominantly affects females because the mutations are usually lethal in males in utero. IP is characterized by abnormalities of neuroectodermal tissues. IP is caused by mutations in a gene called NEMO, which is required to activate the NF-kB pathway. We present a diagnostic protocol for IP and a meta-analysis of the clinical spectrum of IP in 82 patients cited by MEDLINE in the European literature from 2000 to 2006. [References: 31
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