In this contribution, NiO-MgO-SiO2 catalyst was prepared and calcined at different temperatures of 500, 600, 700 and 800 °C. The resulting samples were characterized by BET-BJH, XRD, TPX, ...CO-chemisorption, EDS and SEM analyses. These were employed toward syngas production via propane dry reforming. The increment in the calcination temperature from 500 to 800 °C decreased the basicity of the catalysts. In addition, the active surface area and Ni dispersion were gradually declined by increasing the calcination temperature from 600 to 700 °C due to active metal sintering during the activation process. The calcined sample at 600 °C displayed the highest propane and CO2 conversions of 93% and 78% at the process temperature of 650 °C, respectively. This satisfying performance was supported through sufficient number of active sites combined with appropriate basic characteristic. Meanwhile, the largest amount of coke deposition was detected upon the calcined samples at 500 and 600 °C while at higher calcination temperatures lower carbon formation was obtained. Eventually, the reaction temperature of 650 °C was determined as the optimum temperature achieving moderately high activity and limited by-product formation over the NiO-MgO-SiO2 material. Ultimately, this mixed oxide catalyst was revealed to be very stable as well.
In this research, we converted high silicon fly ash to a high ion-exchange capacity zeolite using a two stages conversion process. Alkaline fusion was applied to collapse the fly ash crystalline ...phases and release Si content. Then Si/Al ratio of the synthesis sol adjusted with appropriate amount of industrial grade materials. A synthesis solution with the molar ratio of 2.2 SiO
2:Al
2O
3:5.28 Na
2O:106 H
2O was hydrothermally crystallized to Na-P1 zeolite at 120
°C for 4
h. The as-synthesized zeolite characterized by means of X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis. Cation exchange capacity of the zeolite was determined using ammonium acetate method. The zeolitization remarkably improved the cation exchange capacity of the final product (e.g. 3.23
meq/g in comparison to the raw fly ash ∼0.005–0.02
meq/g).
Due to the high CEC and sufficient whiteness of the final product, we suggest that the as-synthesized zeolitic powder is a potential candidate as a detergent builder.
Direct steam generation (DSG) in parabolic trough collectors causes an increase to competitiveness of solar thermal power plants (STPP) by substitution of oil with direct steam generation that ...results in lower investment and operating costs. In this study the integrated solar combined cycle system with DSG technology is introduced and techno-economic assessment of this plant is reported compared with two conventional cases. Three considered cases are: an integrated solar combined cycle system with DSG technology (ISCCS-DSG), a solar electric generating system (SEGS), and an integrated solar combined cycle system with HTF (heat transfer fluid) technology (ISCCS-HTF).
This study shows that levelized energy cost (LEC) for the ISCCS-DSG is lower than the two other cases due to reducing O&M costs and also due to increasing the heat to electricity net efficiency of the power plant. Among the three STPPs, SEGS has the lowest CO
2 emissions, but it will operate during daytime only.
The microstructure and micro-texture in different areas of a friction stir (FS)-welded DP600 steel were investigated by means of electron backscatter diffraction. The volume fraction of martensite ...and non-polygonal ferrite was evaluated based on the image quality (IQ) parameter. Analysis of grain boundaries revealed that the fraction of sub-grain boundaries as well as that of low-angle grain boundaries in the heat-affected zone (HAZ) and stir zone (SZ) was more than doubled compared to those in the DP600 steel base metal (BM). The micro-texture examination of the BM showed strong {112} < 110 > and {111} < 112 > components with an intensity 4.6 times of that random texture. The texture showed a memory effect in the HAZ, with a reduced overall intensity. Within the SZ, D
1
, D
2
and E shear texture components together with a cube component were developed. Formation of these texture components of ferrite were attributed to the transformation of B and R texture components of prior austenite, which are evidences of continuous dynamic recrystallization mechanism in the SZ of the friction stir-welded DP600 steel.
We examined the biosynthesis and post-translational processing of the brain-derived neurotrophic factor precursor (pro-BDNF)
in cells infected with a pro-BDNF-encoding vaccinia virus. Metabolic ...labeling, immunoprecipitation, and SDS-polyacrylamide
gel electrophoresis reveal that pro-BDNF is generated as a 32-kDa precursor that is N -glycosylated and glycosulfated on a site, within the pro-domain. Some pro-BDNF is released extracellularly and is biologically
active as demonstrated by its ability to mediate TrkB phosphorylation. The precursor undergoes N-terminal cleavage within
the trans -Golgi network and/or immature secretory vesicles to generate mature BDNF (14 kDa). Small amounts of a 28-kDa protein that
is immunoprecipitated with BDNF antibodies is also evident. This protein is generated in the endoplasmic reticulum through
N-terminal cleavage of pro-BDNF at the Arg-Gly-Leu-Thr 57 -â-Ser-Leu site. Cleavage is abolished when Arg 54 is changed to Ala (R54A) by in vitro mutagenesis. Blocking generation of 28-kDa BDNF has no effect on the level of mature BDNF and blocking generation of mature
BDNF with α 1 -PDX, an inhibitor of furin-like enzymes, does not lead to accumulation of the 28-kDa form. These data suggest that 28-kDa
pro-BDNF is not an obligatory intermediate in the formation of the 14-kDa form in the constitutive secretory pathway.
Polyphenols are a heterogeneous group of phytochemicals that are found in plant-based foods, which have antioxidant and anti-inflammatory properties that may ultimately help protect against chronic ...diseases, such as cancer and cardiometabolic disease. Flavanols (i.e., a subclass of polyphenols), in particular, have been shown to promote glycemic control when consumed with a high-carbohydrate containing food item. Flavanol structures include complex, hydroxylated arrangements, also known as “tannins”, which associate strongly with proteins and thus are notable for their effect on dietary enzymes. Tannins are furthermore divided into non-hydrolysable proanthocyanidin (PAC) and hydrolysable fractions. This review includes recent findings of in vivo and in vitro effects of flavanols/tannins on blood glucose management and inhibition of the digestive enzymes α-amylase and α-glucosidase. Mechanisms underlying the interaction between flavanol structure and glycemic response (e.g., inhibition of starch digestion, altered transport and absorption of glucose, and the altered secretion of gastrointestinal hormones) are discussed, with an emphasis on the molecular basis for flavanol-enzyme interactions that lead to inhibition of enzyme activity.
•Flavanols are polyphenolic constituents that have strong binding affinity to proteins.•Flavanols inhibit digestive enzyme activity and thus have health benefits.•We review recent literature concerning the structure and function of plant flavanols.
Minimizing Hydrogen waste into fuel gas within the H
2 network in a refinery is the objective function of an optimization problem in this paper. The superstructure obtained for a refinery wide ...concept, is first solved and validated for literature cases, then is reduced by heuristic rules, based on engineering judgment. The reduced superstructure contains all simulation procedures of pseudo-components definitions, fine tunings of all unit operations to reach actual operating conditions, reactions characterization, linear and nonlinear equalities and inequalities as system constraints. The set of governing equations are solved with Genetic Algorithm. Based on this optimization, in an Iranian refinery 22.6% reduction of H
2 production and a saving of 1.19 million $/year could be achieved.
Response surface methodology was used to investigate the effects of operating parameters such as impeller speed, binder mass and granulation time on the average size of granules produced in a lab ...scale conical high shear granulator. Two quadratic models were proposed to express granule mean size as a function of impeller speed and binder mass as well as impeller speed and granulation time. It was found out that in the studied domain, the influence of each parameter on granule size differs from one another. While increasing binder mass at constant quantity of powder increased the average size linearly, increasing impeller speed changed the mean size in accordance with quadratic trend. The granule average size was proportional to granulation time and there was an interaction between impeller speed and granulation time. It was also shown that the granule mean size is related to maximum pore saturation (Smax) and Stokes deformation number (Stdef) of granules. Although the equation describes this relationship is applicable in the studied domain, it serves to address using dimensionless groups not only to specify growth regime or breakage probability, but also to determine the granule average size for coalescence or breakage (attrition) dominant regimes.
Display omitted
► Changing binder-powder ratio changes granule average size linearly. ► Changing impeller speed alters granule mean size according to quadratic trend. ► Effect of granulation time on granule size depends on the value of impeller speed. ► Average size of granules is related to growth essential dimensionless numbers.
CTMAB-bentonite was found to be an efficient catalyst for the synthesis of 3,4-dihydropyranocchromene derivatives by one-pot reaction of 4-hydroxycoumarin, aromatic aldehydes, and malononitrile in ...aqueous ethanol under mild condition. High yields, short reaction time, easy work-up, eco-friendly, non-toxic and reusable catalyst are the advantages of this procedure.
Display omitted
•Application of CTMAB-bentonite for the synthesis of dihydropyranocchromenes.•Surfactant modified bentonite presented the highest catalytic activity.•The surfactant modified bentonite was stable in continuous experiments.•The recovered catalyst was reused for five cycles without loss of its activities.•A complete catalytic mechanism is proposed.
In this work, optimization of metalorganic chemical vapor deposition process for uniform layer thickness with especial attention to reactor geometric parameters as decision variables is presented. A ...numerical solution to a steady thermal flow associated with multi-species and chemical reactions in atmospheric pressure axisymmetrical rotating disk reactor by the CFD technique is obtained. Such a simulation is conducted on the assumption that the low Mach number flow is laminar. Then the validation of the numerical results with the benchmark solutions is conducted. Finally, integrating the CFD simulator with an optimization program, based on the Nelder–Mead algorithm, as a new approach is carried out to obtain the optimum value of decision variables. The obtained optimum configuration, results in a decrease in thickness deviation of deposited film from 29.8% to 16.5%.
PDF
