A method based on the linear driving force (LDF) approximation is described to estimate the mass transfer coefficient of molecules adsorbing onto microporous carbons, by using independently measured ...uptake data. This parameter was determined from uptake curves derived from pressure increments during the measurement of isotherm data. To validate the method, simulations for batch uptake were performed and compared to the experimental data in order to obtain the values for the LDF constants. Such values were applied to predict breakthrough curves and compared to experimental data. The proposed method to estimate the LDF coefficient can be adequate to obtain a more physically meaningful value of the mass transfer coefficient.
A simple procedure to estimate the mass transfer coefficients for CO2 and N2 in microporous activated carbon was developed based on uptake experiments typically used to obtain equilibrium isotherms. The estimated parameters helped to simulate breakthrough curves, which were compared to experimental data. An excellent match was observed, indicating the good reliablity of the presented method.
In this study, two configurations of Temperature Swing Adsorption (TSA) were assessed with the aim of evaluating their efficacy on CO
2
capture on commercial adsorbent zeolite 13X within a ...post-combustion scenario. A fixed bed setup was employed to measure breakthrough curves from the adsorption and desorption steps. Considering a dry desulfurized flue gas stream, breakthrough curves for CO
2
–N
2
(15/75 % v/v) in Helium were performed at 25, 50 and 75 °C. The desorption step was carried out following two TSA regeneration strategies: a two-step desorption arrangement (
configuration 1
) consisting of a purging phase followed by a heating-purging phase, and a one-step desorption arrangement (
configuration 2
) involving only the heating-purging phase. Adsorption equilibrium isotherms were also obtained for pure CO
2
(25, 50, 75, 100 and 125 °C) and N
2
(25, 50 and 75 °C) on zeolite 13X in the range of 0–1 bar. Finally, a mathematical model considering mass and energy differential balances was used to predict the whole adsorption-desorption history. The results obtained on breakthrough curves showed that CO
2
separation from N
2
on zeolite 13X is accomplished by adsorption under the studied conditions with a marked selectivity for CO
2
. In regards to the desorption phase,
configuration
1 may not be adequate for an integration of adsorption-desorption steps once only the purge phase duplicates the desorption time as compared to the adsorption stage. On the other hand,
configuration 2
is more likely to synchronize the whole adsorption—desorption process since the regeneration time was significantly reduced by this strategy. However,
configuration 1
managed to obtain full CO
2
recovery with all the temperatures tested during the heating step, whereas
configuration 2
reached recovery values around 92%. Moderate temperatures (e.g. 125–150 °C) are feasible to be used for
configuration 2
regeneration strategy so as to avoid energy penalties. Simulations were able to reproduce well the experimental breakthrough curves, even though some discrepancies were observed in the desorption histories.
The alternating movement of the inlet valve and the piston of an internal combustion engine generates pressure waves propagating along the intake duct. This phenomenon alters the admitted air mass ...flow inside the engine cylinder in some speed ranges. To mitigate the harmful effects of the wave phenomenon, acoustic elements are inserted into the intake system, such as Helmholtz resonators, plenums and Herschel-Quincke tubes. This paper aims to numerically evaluate the air flow in the intake ducts using Herschel-Quincke tubes. The numerical study was carried out using software based on the Characteristics Method, which, considering the one-dimensional transient flow, simulates the wave phenomena inside the ducts. As a result, it was observed that the Herschel-Quincke tubes reduce the pressure amplitude at the inlet valve port, increasing the air flow velocity and the intake air mass flow.
Pure component adsorption equilibrium of CH
4
and CO
2
on activated carbon have been studied at three different temperatures, 298, 323, and 348 K within a pressure range of 10-2000 kPa. Binary ...adsorption equilibrium isotherm was described using extended Sips equation and ideal adsorbed solution theory (IAST) model. Experimental breakthrough curves of CO
2
/CH
4
(40:60 in a molar basis) were performed at four different pressures (300, 600, 1200, and 1800 kPa). The experimental results of binary isotherms and breakthrough curves have been compared to the predicted simulation data in order to evaluate the best isotherm model for this scenario. The IAST and Sips models described significantly different results for each adsorbed component when higher pressures are set. These different results cause a significant discrepancy in the estimation of the equilibrium selectivity. Simulated and experimental equilibrium selectivity data provided by IAST presented values of around 4, for CO
2
/CH
4
, and extended Sips presented values of around 2. Also, simulated breakthrough curves showed that IAST fits better to the experimental data at higher pressures. According to the simulations, in a binary mixture at total pressure over 800 kPa, extended Sips model underestimated significantly the CO
2
adsorbed amount and overestimated the CH
4
adsorbed amount.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A violência intrafamiliar é aquela praticada por familiares, constituindo-se em grave violação dos direitos da criança e do adolescente. O objetivo desse estudo foi investigar se Agentes Comunitários ...de Saúde (ACS) reconhecem sinais de violência intrafamiliar, se fazem notificação, se conhecem fatores de risco e proteção e se na sua formação receberam informações sobre essas temáticas. Participaram do estudo 119 ACS que responderam três questionários. Constatou-se que os conhecimentos sobre sinais de violência, em especial, de violência sexual e psicológica, sobre notificação, sobre fatores de risco e proteção e sobre práticas parentais e habilidades sociais infantis deveriam fazer parte de cursos de capacitação dos ACS, bem como de toda a Equipe de Saúde, pelo fato de atuarem cotidianamente com as famílias no território. Conclui-se que os ACS não tiveram acesso aos conhecimentos produzidos pela psicologia do desenvolvimento infantil que poderiam orientar sua ação protetiva e preventiva junto às famílias.
Objective
Using a mouse osteoporotic model, this study aimed to determine the influence of hydrophilic titanium surfaces on gene expression and bone formation during the osseointegration process.
...Background
Based on the previous evidence, it is plausible to assume that osteoporotic bone has a different potential of bone healing. Therefore, implant surface modification study that aims at enhancing bone formation to further improve short‐ and long‐term clinical outcomes in osteoporosis is necessary.
Material and Methods
Fifty female, 3‐month‐old mice were included in this study. Osteoporosis was induced by ovariectomy (OVX, test group) in 25 mice. The further 25 mice had ovaries exposed but not removed (SHAM, control group). Seven weeks following the ovariectomy procedures, one customized implant (0.7 × 8 mm) of each surface was placed in each femur for both groups. Implants had either a hydrophobic surface (SAE) or a hydrophilic treatment surface (SAE‐HD). Calcium (Ca) and phosphorus (P) content was measured by energy‐dispersive X‐ray spectroscopy (EDS) after 7 days. The femurs were analyzed for bone‐to‐implant contact (BIC) and bone volume fraction (BV) by nano‐computed tomography (nano‐CT) after 14 and 28 days. Same specimens were further submitted to histological analysis. Additionally, after 3 and 7 days, implants were removed and cells were collected around the implant to access gene expression profile of key osteogenic (Runx2, Alp, Sp7, Bsp, Sost, Ocn) and inflammatory genes (IL‐1β, IL‐10, Tnf‐α, and Nos2) by qRT‐PCR assay. Statistical analysis was performed by ANOVA and paired t test with significance at P < .05.
Results
The amount of Ca and P deposited on the surface due to the mineralization process was higher for SAE‐HD compared to SAE on the intra‐group analysis. Nano‐CT and histology revealed more BV and BIC for SAE‐HD in SHAM and OVX groups compared to SAE. Analysis in OVX group showed that most genes (ie, ALP, Runx2) involved in the bone morphogenetic protein (BMP) signaling were significantly activated in the hydrophilic treatment.
Conclusion
Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE‐HD presented a faster response in terms of bone formation and osteogenic gene expression compared to SAE. Hydrophilic surface in situations of osteoporosis seems to provide additional benefits in the early stages of osseointegration.
Intestinal parasitic infections are one of the main debilitating conditions that affect horses. Grazing, natural habits, the way of breeding and the unrestrained use of dewormers favor the ...development of parasites, make their control difficult and cause parasite resistence to commonly used active ingredientes. Parasites, in addition to causing economic losses directly related to pathologies and clinical manifestations, such as reduce performance and development of affected animals, can favor the development of other conditions such as colic sydrome and other possibilities. Among the species that affect the equine species, the most prominent parasite is Strongylus vulgaris, wich, during its evolutionary cycle, migrates throhgh the animals bodies through blood vessels, and can affect diferente systems, explaining its importante pathogenesis. The formation of thrombi in importante vessels within the organismo of parasitized animals is notable, which is suficiente for the development of other pathologies.
As infecções parasitárias intestinais são uma das principais afecções debilitantes que acometem os equinos. O pastejo, hábitos naturais, a forma de criação e o uso desenfreado de vermífugos favorecem o desenvolvimento de parasitoses, dificultam seu controle e causam a resistência parasitária aos princípios ativos comumente utilizados. As parasitoses, além de acarretarem perdas econômicas diretamente relacionadas às patologias e manifestações clínicas, como em diminuição do desempenho e desenvolvimento dos animais acometidos, podem favorecer o desenvolvimento de outras afecções como síndrome cólica e outras possibilidades. Dentre das espécies que acometem os equinos, o parasita com maior importância e que tem maior destaque é o Strongylus vulgaris, que durante seu ciclo evolutivo, ocorre migração pelo organismo dos animais através dos vasos sanguíneos, podendo afetar diferentes sistemas, explicando sua importante patogenia. É notória a formação de trombos em importantes vasos dentro do organismo dos animais parasitados, sendo suficiente para o desenvolvimento de outras patologias.
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