3D Insulator‐based dielectrophoresis using DC‐biased,AC electric fields for selective bacterial trapping

Insulator‐based dielectrophoresis (iDEP) is a well‐known technique that harnesses electric fields for separating, moving, and trapping biological particle samples. Recent work has shown that utilizing DC‐biased AC electric fields can enhance the performance of iDEP devices. In this study, an iDEP device with 3D varying insulating structures analyzed in combination with DC biased AC fields is presented for the first time. Using our unique reactive ion etch lag, the mold for the 3D microfluidic chip is created with a photolithographic mask. The 3D iDEP devices, whose largest dimensions are 1 cm long, 0.18 cm wide, and 90 μm deep are then rapidly fabricated by curing a PDMS polymer in the glass mold. The 3D nature of the insulating microstructures allows for high trapping efficiency at potentials as low as 200 Vpp. In this work, separation of Escherichia coli from 1 μm beads and selective trapping of live Staphylococcus aureus cells from dead S. aureus cells is demonstrated. This is the first reported use of DC‐biased AC fields to selectively trap bacteria in 3D iDEP microfluidic device and to efficiently separate particles where selectivity of DC iDEP is limited.     

Magnetic nanoparticles Fe3O4-supported guanidine as an efficient nanocatalyst for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

Research on Chemical Intermediates - Here, the application of guanidine supported on magnetic nanoparticles Fe3O4 (MNPs-guanidine) as a novel magnetically separable base nanocatalyst is described....     

Powers of t -spread principal Borel ideals

We prove that t-spread principal Borel ideals are sequentially Cohen–Macaulay and study their powers. We show that these ideals possess the strong persistence property and compute their limit depth.     

Supply chain performance evaluation using fuzzy network data envelopment analysis: a case study in automotive industry

Supply chain performance evaluation problems are evaluated using data envelopment analysis. This paper proposes a fuzzy network epsilon-based data envelopment analysis for supply chain performance evaluation. In the common data envelopment analysis models which are used for evaluation of decision-maker units efficiency, there are several inputs and outputs. One of the bugs of such models is that the intermediate products and linking activities are overlooked. Considering these intermediate activities and products, the current study evaluates the performance of decision-maker units in an automotive supply chain. There are ten decision-maker units in the supply chain in which there are three suppliers, two manufacturers, two distributors, and four customers. Moreover, the overall efficiency of input-oriented (input-based) model and input-oriented divisional efficiency are calculated. In order to improve the efficiencies, the projections onto the frontiers are obtained by using the outputs of the solved model and Lingo software. In order to show the applicability of the proposed model, it is applied on automotive industry, as a case study, to evaluate supply chain performance. Then, the overall efficiencies of DMUs and each sections (divisions) of DMUs were calculated separately. Therefore, every organization can apply this evaluation method for improving the performance of alternative factors.

     

Fluorescent imidazolium-based cyclophane for detection of guanosine-5'-triphosphate and I(-) in aqueous solution of physiological pH

A new water-soluble and fluorescent imidazolium-anthracene cyclophane (1) effectively recognizes the biologically important GTP and I(-) over other anions in a 100% aqueous solution of physiological pH 7.4. Fluorescence and (1)H NMR spectra and ab initio calculations demonstrate that emission arises from the formation of an excimer state and quenching occurs upon GTP/I(-) binding through (C-H)(+)···A(-) hydrogen bond interactions.     

Fabrication of high thermal stable cured novolac/Cloisite 30B nanocomposites by chemical modification of resin structure

Cloisite 30B as a modified kind of nanoclay was utilized for the formation of 3D network based on novolac resin with high thermal stable properties. Two types of phenolic resins including neat novolac (NR) and modified novolac resin were used to create a compatible matrix with nanoclay. For this purpose, NR modified with (3‐chloropropyl)triethoxysilane (CPTES) to form SiNR. For improvement of thermal behaviors, Cloisite 30B was dispersed in matrix via ultrasonic waves and cured with hexamethylenetetramine (HMTA) to form 3D network. X‐ray diffraction (XRD) analysis was used to measure the d‐spacing in intercalated systems and results indicated the optimum amount of clay for appropriate thermal properties. Investigation of the thermal properties of the samples by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the presence of Cloisite 30B in matrix resulted in much higher thermal stability and char yield with respect to modification of novolac resin originated from formation of 3D Si–O–Si network. Also, cured modified resin and its nanocomposites showed much higher thermal stability than cured NR and its nanocomposites. Such nanocomposite materials with high thermal stability have potential applications in advanced fields such electronic, industrial molds, coatings, adhesives, and aerospace composites.     

On the <Emphasis Type="Italic">L</Emphasis><Superscript><Emphasis Type="Italic">p</Emphasis></Superscript>-conjecture for locally compact groups

Let G be a locally compact group. For 1 < p < ∞, it is well-known that f * g exists and belongs to L^p(G) for all f, g L^p (G) if and only if G is compact. Here, for 2 < p < ∞, we show that f * g exists for all f, g L^p(G) if and only if G is compact. We also show that this result does not remain true for 1 < p ≤ 2. Received: 23 April 2006