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31.
In this paper, we report a feasible protocol for the preparation of [1]benzopyranopyrido[d]pyrimidines via expeditious sonochemical route. The reaction efficiency was evaluated by influence of several parameters including sonication power, sonication time, different solvents, and using porous graphene/MoO3 nanocomposite as catalyst, for the first time. The effect of the ultrasonication comparing with the conventional heating on the synthesis of the titled compounds shows that the ultrasonic irradiation is required to rich the cyclized products. The structural properties of porous graphene/MoO3 nanocomposite were determined by Fourier transform infrared spectroscopy (FT‐IR), powder X‐ray diffractometry (XRD), scanning electron microscope (SEM), Raman spectroscopy, and also by TGA analysis. Confirmation of the structures of compounds 4a – 4h were also established with IR, 1H NMR, and 13C NMR spectroscopic data and also by elemental analyses.  相似文献   
32.
The magnetic biocompatible rod-like ZnS/CuFe2O4/agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as-prepared catalyst was characterized by several techniques such as Fourier transform-infrared spectroscopy, energy-dispersive X-ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X-ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe2O4/agar nanobiocomposite was assessed in sequential Knoevenagel condensation–Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%–97%) in very short reaction times (3–18 min), and with no need for complicated work-up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency.  相似文献   
33.
An efficient synthesis of hexahydropyrido[2,3-d]pyrimidinetrione derivatives is achieved via tandem Knoevenagel-Michael addition of aromatic aldehydes,methylcyanoacetate and 4(6)-aminouracil in solvent-free conditions in the presence of 10 mol%of ZrO2 nanoparticles(ZrO2 NPs) as a heterogenous catalyst.The procedure is formed in high yields,short reaction time and an environmentally friendly specificity.  相似文献   
34.
Ding X  Shi J  Lin SC  Yazdi S  Kiraly B  Huang TJ 《Lab on a chip》2012,12(14):2491-2497
We have developed an acoustic-based tunable patterning technique by which microparticles or cells can be arranged into reconfigurable patterns in microfluidic channels. In our approach, we use pairs of slanted-finger interdigital transducers (SFITs) to generate a tunable standing surface acoustic wave field, which in turn patterns microparticles or cells in one- or two-dimensional arrays inside the microfluidic channels--all without the assistance of fluidic flow. By tuning the frequency of the input signal applied to the SFITs, we have shown that the cell pattern can be controlled with tunability of up to 72%. This acoustic-based tunable patterning technique has the advantages of wide tunability, non-invasiveness, and ease of integration to lab-on-a-chip systems, and shall be valuable in many biological and colloidal studies.  相似文献   
35.
A new method for ultrathin grafting of pNIPAm on PDMS surfaces is introduced that employs plasma activation of the surface followed by thermal polymerization. This method is optimized for human primary SMC attachment and subsequent intact cell sheet detachment by lowering the temperature. The contractile gene expression of the cells showed that the contractile phenotype of the SMCs which is induced by aligning the cells through micropatterning is more preserved after thermoresponsive cell sheet detachment in contrast with enzymatic detachment. Given its simplicity and low cost, this thermoresponsive grafting method can be utilized for engineering patterned cell sheets for future bottom‐up tissue engineering techniques.

  相似文献   

36.
A simple,efficient and high yielding approach for the synthesis of indeno[1,2-b]quinolinediones has been developed by a one-pot,four-component,coupling reaction utilizing TiO2 nanoparticles(TiO2-NPs) as a heterogeneous catalyst at 80℃in aqueous media.  相似文献   
37.
38.
In this study, copper chromite nanoparticles (CuCr2O4 NPs) were prepared by a simple hydrothermal method. This nanomaterial was found as an efficient heterogeneous catalyst for the synthesis of a new class of [1]benzopyran azo dyes via pseudo-three-component reaction of (E)-1,2-diphenyl-1-diazene with 4-hydroxycoumarin in the ratio 1:2. The aim of the present work was to provide a practical and high yielding protocol that offers several advantages such as simple procedure with an easy work-up, mild reaction conditions, and the use of CuCr2O4 NPs as an efficient and easily recoverable catalyst.  相似文献   
39.
A simple one-pot method for the preparation of 7-amino-2,4-dioxo-5-aryl-1,2,3,4-tetrahydropyrido[2,3- d]pyrimidine-6-carbonitriles 4 from aromatic aldehydes, malononitrile and 4(6)-aminouracil in the presence of ZrO2 nanoparticles (ZrO2 NPs) as an efficient heterogeneous catalyst is described. The procedure has the advantages of high yields (86-97%), short reaction time (2h) and an environmentally friendly specificity.  相似文献   
40.
Shi J  Yazdi S  Lin SC  Ding X  Chiang IK  Sharp K  Huang TJ 《Lab on a chip》2011,11(14):2319-2324
Three-dimensional (3D) continuous microparticle focusing has been achieved in a single-layer polydimethylsiloxane (PDMS) microfluidic channel using a standing surface acoustic wave (SSAW). The SSAW was generated by the interference of two identical surface acoustic waves (SAWs) created by two parallel interdigital transducers (IDTs) on a piezoelectric substrate with a microchannel precisely bonded between them. To understand the working principle of the SSAW-based 3D focusing and investigate the position of the focal point, we computed longitudinal waves, generated by the SAWs and radiated into the fluid media from opposite sides of the microchannel, and the resultant pressure and velocity fields due to the interference and reflection of the longitudinal waves. Simulation results predict the existence of a focusing point which is in good agreement with our experimental observations. Compared with other 3D focusing techniques, this method is non-invasive, robust, energy-efficient, easy to implement, and applicable to nearly all types of microparticles.  相似文献   
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