In this research, a simple aliphatic –N
2
O
2
Schiff base ligand was synthesized and immobilized on magnetite–silica nanoparticles. Supported tetradentate Schiff base ligand was converted to Cu(II) ...Schiff base complex as a result of a reaction with copper acetate salt. The Schiff base ligand was synthesized by the condensation reaction between benzoyl acetone and ethylenediamine in a ratio of 2:1. Magnetite silica (Fe
3
O
4
@SiO
2
) nanoparticles were prepared and functionalized by –NH
2
groups. This functionalization was done as a result of the reaction between magnetite–silica and 3-amino propyl triethoxysilane (APTES) in dry toluene. The immobilized Schiff base ligand prepares through the condensation reaction between –NH
2
groups of functionalized magnetite–silica and C=O groups of Schiff base. So, the coordination mode of the immobilized Schiff base is –N
3
O. Then immobilized Schiff base was converted to Cu(II) complex. The immobilized Cu(II) complex was characterized by techniques such as FT-IR, VSM, XRD, FE-SEM, EDX, TGA-DTA, and AAS. The catalytic property of the nanoparticles was evaluated for the synthesis of the 1-amidoalkyl-2-naphthols. Magnetic solid base catalysts have great potential for easy catalyst separation with magnetic force, which reduces the catalyst loss and improves its post-reaction recovery. Besides, the small particle size with a high surface area also allows better interaction with reactants and improves the yields of the reaction.
In this work a new core–shell nanocatalyst, Fe
3
O
4
@SiO
2
/Schiff base of Ni(II), (Fe
3
O
4
@SiO
2
/SB(Ni)), was synthesized and characterized. The Schiff base immobilized on magnetite ...nanoparticles introduced in this study, is a simple and aliphatic Schiff base. The synthesis steps were meticulously followed. First, magnetite-silica nanoparticles were prepared and functionalized by –NH
2
groups using 3-amino propyl triethoxysilane (APTES). Subsequently, the aliphatic Schiff base ligand was immobilized through a condensation reaction between the –NH
2
groups on the magnetite-silica and the –C=O groups of acetylacetone. The supported Schiff base complex of Ni(II) on magnetite-silica was synthesized by a reaction between immobilized Schiff base and Ni(II) acetate tetrahydrate salt. Finally, the immobilized Ni(II) Schiff base complex was fully characterized using several techniques including, FT-IR, VSM, XRD, FE-SEM, EDX, TEM, BET, TGA-DTA, and AAS. The magnetically recoverable core–shell nanocatalyst
,
demonstrated remarkable catalytic activity in the synthesis of 3,4-dihydropyrimidine-2-(1H)-one. This reaction involved three components: an aldehyde, β-keto ester, and urea, and was carried out via the solvent-free Biginelli reaction
.
The results indicate that the products are synthesized in good to excellent yields (82–91%) within 13–22 min. At the end of the reaction, the nanocatalyst can be easily removed from the reaction mixture using an external magnet and reused several times. The synthesized products were purified and characterized by FT-IR and
1
H NMR techniques.
Graphical abstract
Asprosin, a newly identified adipokine, is pathologically increased in individuals with insulin resistance. However, the available evidence on the association of asprosin and type 2 diabetes mellitus ...(T2DM) status is still scarce. Therefore, this study aimed to determine the relationship between serum concentrations of asprosin and T2DM status.
This observational study was performed based on 194 adults (97 newly diagnosed T2DM and 97 healthy individuals). Anthropometric and biochemical variables were determined in all participants. Serum concentrations of asprosin were measured using enzyme-linked immunosorbent assay (ELISA).
In patients with T2DM, the serum concentrations of asprosin were significantly higher than the healthy controls (4.18 IQR: 4.4 vs. 3.5 IQR: 1.85, P < 0.001). The concentrations of asprosin were significantly correlated with body mass index (BMI) and fasting blood glucose (FBG) in healthy subjects and with BMI, FBG, hemoglobin A1c (HbA1c), homeostatic model assessment of insulin resistance (HOMA-IR), and quantitative insulin check index (QUICKI), triacylglycerol (TAG) and total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C) ratio in the T2DM group. In fully adjusted model, the odds ratio (OR) of T2DM with serum concentrations of asprosin was approximately 1.547 (95% CI 1.293-1.850, P < 0.001) compared to the control group. Multiple stepwise regression analysis indicated that FBG and HOMA-IR were independently associated with asprosin in T2DM.
Our findings indicated that serum concentrations of asprosin are increased in patients with T2DM. Also, asprosin is correlated with insulin resistance and TC/HDL-C ratio (atherosclerotic risk factor of cardiovascular diseases) in patients with T2DM.
In this research, magnetite nanoparticles as the core are fabricated by co-precipitation method from Fe(II) and Fe(III) chloride salts and then the surfaces of the nanoparticles are modified to ...improve their performance. These modifications include the coating of silica and then the second layer by 3-amino propyl triethoxy silane (APTES) which causes the functionalization of magnetite nanoparticles with –NH
2
groups. In the next step, an aliphatic tetra-dentate N
2
O
2
Schiff base was synthesized separately by condensation reaction between benzoyl acetone and ethylenediamine. This free Schiff base has two C = O groups. By the condensation reaction between one C = O group of free Schiff base and –NH
2
group of functionalized magnetite silica, a tetra-dentate N
3
O Schiff base is immobilized on the magnetite silica surface. This tetra-dentate Schiff base supported on magnetite silica is a very good structure for the formation of stable metal complexes. The immobilized Schiff base was converted to the Ni(II) Schiff base complex by the reaction with Ni(II) acetate tetra-hydrate. This Ni(II) Schiff base complex is immobilized on magnetite silica and shown as Fe
3
O
4
@SiO
2
/Schiff base of Ni(II). This core-shell nanostructure is fully characterized by techniques such as FT-IR, VSM, XRD, FE-SEM, EDX, TGA-DTA, AAS, BET, and BJH. In the last step, this nanocatalyst is used as an efficient catalyst for the solvent-free synthesis of amido alkyl naphthols by the condensation reaction between an aldehyde, 2-naphthol, and an amide. The reaction was monitored by TLC. At the end of the reaction, the nanocatalyst was removed easily from the reaction mixture by an external magnet. The products of 1-amidoalkyl-2-naphthols were identified by FT-IR and
1
HNMR techniques. Finally, the percentage yield of the reaction is calculated by measuring the mass of 1-amidoalkyl-2-naphthol synthesized in the presence of the catalyst.
•Treadmill exercise attenuated apoptosis-induced neuropathology in ovariectomized rat hippocampus.•Treadmill exercise inhibited apoptosis and improved neuronal survival in diabetic rat ...hippocampus.•Treadmill exercise significantly recovered acetylcholinesterase activity in diabetic rat hippocampus.•Treadmill exercise had no neuroprotective effects in ovariectomized diabetic rat hippocampus.
To determine detrimental effects of estrogen and insulin deficiencies on hippocampus, we examined apoptosis-induced neuronal damage and cholinergic system in ovariectomized and/or diabetic rat hippocampus. Possible neuroprotective effects of treadmill exercise were also investigated. Adult female Wistar rats were randomly divided into four groups (n = 5 rats/group) as follows: control, ovariectomized (Ovx), diabetic (Dia, streptozotocin (STZ) 60 mg/kg; i.p.), and Ovx + Dia groups. Each group was further subdivided into exercise and non-exercise groups. Animals in exercise groups were subjected to treadmill training, while those in non-exercise groups were placed on the stationary treadmill for 4 weeks (5 days/week). Apoptosis-related protein levels (i.e. Bax, Bcl-2, and caspase-3), number of survived neurons, and acetylcholinesterase (AChE) activity in the hippocampus were measured using Western blotting, Cresyl Violet staining, and Ellman assay, respectively. Both ovariectomy and diabetes increased expression of Bax and caspase-3 and decreased expression of Bcl-2 at protein levels. In addition, a significant decrease in the number of survived neurons was observed in both Ovx and Dia groups, while AChE activity was lower only in the Dia group. The Ovx + Dia group showed stronger apoptosis-induced neuropathology and inhibition of AChE activity. Treadmill exercise attenuated apoptosis-induced neuropathology in the Ovx and Dia groups and recovered AChE activity in the Dia group. Neuroprotective effects of treadmill exercise were mediated by inhibition of apoptosis. Moderate exercise protocol had no beneficial anti-apoptotic and neuroprotective effects in ovariectomized-diabetic rats.
Fabrication method is one of the essential factors which directly affect on the properties of scaffold. Several techniques have been well established to fabricate nanofibrous scaffolds such as ...electrospinning. However, preparing a three-dimensional (3-D) interconnected macro-pore scaffold essential for transporting the cell metabolites and nutrients is difficult using the electrospinning method. The main aim of this study was developing a highly porous scaffold by poly (L-lactic acid) (PLLA)/chitosan blend using liquid–liquid phase separation (LLPS) technique, a fast and cost–benefit method, in order to use in nerve tissue engineering. In addition, the effect of different polymeric concentrations on morphology, mechanical properties, hydrophilicity, in vitro degradation rate and pH alteration of the scaffolds were evaluated. Moreover, cell attachment, cell viability and cell proliferation of scaffolds as candidates for nerve tissue engineering was investigated. PLLA/chitosan blend not only had desirable structural properties, porosity, hydrophilicity, mechanical properties, degradation rate and pH alteration but also provided a favorable environment for attachment, viability, and proliferation of human neuroblastoma cells, exhibiting significant potential for nerve tissue engineering applications. However, the polymeric concentration in blend fabrication had influence on both characteristics and cell responses. It concluded that PLLA/chitosan nanofibrous 3-D scaffold fabricated by LLPS method as a suitable candidate for nerve tissue engineering.
Simulated moving bed reactors (SMBRs) are hybrid reactors that perform reaction and separation processes simultaneously in a single unit. Their high separation performance and ability to overcome ...equilibrium constraints on the reaction make them effective in a wide range of equilibrium reactions. This study investigated an SMBR for xylene isomerization and separation of p‐xylene from other xylene isomers (free of ethylbenzene) in the liquid phase. The effects of operating variables including temperature, switching time, and columns arrangement on the performance parameters and optimal conditions were determined. Due to the removal of products from the reaction site, the SMBR drives the chemical equilibrium toward producing more product than a conventional reactor under the same conditions.
p‐Xylene, the precursor of terephthalic acid, is the most important xylene isomer. Hence, isomerization of xylenes and separation of p‐xylene from other xylene isomers were studied in a simulated moving bed reactor performing the reaction and separation processes simultaneously in a single unit. The effects of variables such as temperature, switching time, and column arrangement were investigated.
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Resistance spot welding (RSW) is frequently accompanied by expulsion, an undesirable event taking place in manufacturing processes, including car body production. Many variables are ...involved in RSW, all of which can affect expulsion. This investigation aimed at developing an analytical model for predicting expulsion in RSW. Accordingly, based on force and moment balances, a criterion was established. It was proposed that expulsion took place when the molten metal ejected as a result of the pressure inside nugget. The model presented here considered that the pressure inside the nugget was mainly due to melting transformation and liquid thermal expansion. Hence, the model took into account the effects of nugget diameter, electrode force, base material yield stress, sheet thickness, and joint fit-up to predict the occurrence of expulsion. To assess the model, a number of experiments were done, where the effects of welding current, electrode force, sheet thickness, and galvanization coating of the steel were studied. Regarding the effects of electrode force and welding current, the prediction made by the analytical model was consistent with the results obtained from the experiments. However, it was observed that expulsion in the galvanized steel sheets occurred at larger nugget diameters. The macroscopic examination of the welded samples showed that, with galvanization the ability for a better electrode fit-up was increased, and according to the model this could result in thereby increasing the critical nugget size.
Modeling and implementation of biological neural networks are significant objectives of the neuromorphic research field. In this field, neuronal synchronization plays a significant role in the ...processing of biological information. This paper presents a set of piecewise linear (MLPWL1) and multiplierless piecewise linear (MLPWL2) neuron models, which mimic behaviors of different types of neurons, similar to the biological behavior of conductance-based neurons. Both simulations and a low-cost digital implementation are carried out to compare the proposed models to a single ML neuron and two coupled ML neurons, demonstrating the required range of dynamics with a more efficient implementation. Hardware implementations on a field-programmable gate array (FPGA) show that the modified models mimic the biological behavior of different types of neurons with higher performance and significantly lower implementation costs compared to the previous realizations of the ML model. The mean normalized root mean square errors (NRMSEs) of the MLPWL1 and MLPWL2 models are 3.70% and 4.89%, respectively, as compared to the original ML model.
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