A novel report on Eosin Y functionalized MWCNT as an initiator for ring opening polymerization of ɛ-caprolactone

This research conducted ring opening polymerization (ROP) of ?-caprolactone (C.L.) with a novel initiator, namely; Eosin Y functionalized multiwalled carbon nanotube (MWCNT) at 140 °C with nitrogen sparge under different concentrations. ROP of C.L. carried out at two different experimental conditions similar to variations in [M₀/I₀] and [C.L.]. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of MWCNT-Eosin Y initiated ROP of C.L. Gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), UV–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) further characterized the structure. UV–visible spectroscopy determined the binding constant (K), for samples prepared under different [C.L.].     

Synthesis and characterizations of novel acid functionalized and fluorescent poly(ε-caprolactone)

ε-Caprolactone (CL) was subjected to ring opening polymerization (ROP) under inert (nitrogen) atmosphere at 413 K for 1 h in the presence of stannous octoate (SO) as a catalyst and Eosin Y, a xanthenes type dye as a novel chemical initiator. The ROP was carried out at two different experimental conditions, namely at various concentrations of initiator and monomer, to get more scientific information from the resultant product. Thus, obtained Eosin Y conjugated poly(ε-caprolactone) (PCL) was characterized by different analytical tools like FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography (GPC), UV–Visible spectroscopy, photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). Finally, the morphology of the Eosin Y conjugated PCL was studied by scanning electron microscopy (SEM). The binding constant (K) was determined from both UV–Visible spectroscopy and PL spectroscopy, and the static quenching mechanism was proposed. The number of binding site (n) was also determined from PL spectroscopy and the results were compared with the FTIR-RI method.     

Bubble growth and ink ejection process of a thermal ink jet printhead

The present study investigated bubble growth and the ink ejection process of a thermal ink jet (TIJ) printhead with a thin-film heater on the bottom-wall of the ink nozzle. Numerical predictions are presented for bubble volume, temperature, and pressure, and ink jet ejection length under various heating conditions. An inexpensive optical system was set up to visualize the transient ink ejection process. Experimental results to show the effect of the heating pulse conditions on the ejected droplet volume and ejected ink length are also presented. The experimental and numerical results agree well on both the ejected ink length for shorter time history (< 6 μs) and the threshold operating voltage for the ink ejection.     

Improvement on thermal performance of a disk-shaped miniature heat pipe with nanofluid

The present study aims to investigate the effect of suspended nanoparticles in base fluids, namely nanofluids, on the thermal resistance of a disk-shaped miniature heat pipe [DMHP]. In this study, two types of nanoparticles, gold and carbon, in aqueous solution are used respectively. An experimental system was set up to measure the thermal resistance of the DMHP with both nanofluids and deionized [DI] water as the working medium. The measured results show that the thermal resistance of DMHP varies with the charge volume and the type of working medium. At the same charge volume, a significant reduction in thermal resistance of DMHP can be found if nanofluid is used instead of DI water.     

Pool boiling of nanoparticle-modified surface with interlaced wettability

ABSTRACT: This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller.     

Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H₂O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications.     

Fabrication of hierarchical structured superhydrophobic Copper surface by in-situ method with micro/nano scaled particles

Chlorofluoro silane (CFSi) decorated Copper doped SiO₂ coated Copper surface was synthesized by an in-situ method and characterized by various analytical tools like Fourier Transform Infrared (FTIR) Spectroscopy, UV-Visible spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and contact angle measurements. In the present investigation, the bulk Copper plate was served as a resource material for the generation of Copper with simultaneous chemical etching reaction in an aqueous acidic and alcoholic medium. The modified Copper surface has a contact angle of 152°.     

Pressure response and droplet ejection of a piezoelectric inkjet printhead

The present study aims to investigate the pressure rise in the ink flow channel and the ink droplet formation process of a piezoelectric printhead after an electrical pulse is applied to the printhead. The ink flow channel is modeled as a straight circular pipe followed by a convergent nozzle. Both numerical analysis and experimental observations are performed in this study. In the numerical analysis, a characteristic method is used to solve the one-dimensional wave equation to obtain the transient pressure and velocity variations in the flow channel of the printhead. In this analysis, the channel is assumed to have a non-uniform cross section. In addition, a flow visualization system was set up to observe the ink droplet injection process. After the piezoelectric material is driven by the input electric pulse, the ink droplet images are immediately captured by a charge-couple device (CCD) camera converted to a digital image via a frame grabber, and stored in a computer. The results obtained from the experimental observations are also compared with the numerical prediction. The effects of electric pulse shape and voltage on the ink injection length and the ejected droplet weight are also presented.     

Development of an integrated CMOS DNA detection biochip

This paper presents a CMOS DNA detection biochip using an electrical detection method with self-assembly multilayer gold nanoparticles (AuNPs). Each measuring spot of this biochip consists of three major parts; a pair of electrodes with a nanogap, a current amplifier circuit, and a heater with an embedded temperature sensor. The biochip is first fabricated by a TSMC (Taiwan Semiconductor Manufacturing Company Ltd.) 0.35 μm 2P4M standard CMOS process. Then, post-CMOS micromachining etch processes are used to expose the surface of the nanogap to test samples for the establishment of multilayer AuNPs through hybridization between single strand DNAs in the samples. The gap distance between a pair of electrodes is 350 nm. Before taking DNA detection measurements, self-assembly monolayer AuNPs is established on the nanogap surface between two microelectrodes. Multilayer AuNPs can be observed if hybridization between single strand DNAs occurs. An approximately 1000-fold increase in electric current between the multilayer AuNPs over the monolayer AuNPs serves an indication of the presence of target DNA in test samples. After integrating the electrodes with an embedded current amplifier, the electric current of multilayer AuNPs is amplified to the order of mA that can be easily measured by a commercial Volt-Ohm-Milliammeter. The heating system with a heating element and a temperature sensor can be used to distinguish single base-pair mismatch hybridization from complementary hybridization for the establishment of multilayer AuNPs. The lowest detectable concentration of target DNA on this biochip is 0.1 nM.     

Axial particle displacements in fluid slugs after passing a simple serpentiform microchannel

In this work, we designed a simple microchannel to separate particles in fluids by size. We found that mixtures of polystyrene 2 and 0.5 μm particles in a fluid slug can be differentiated by size after passing a long serpentiform microchannel. In contrast to the tubular pinch effect, which separates the particle in radial direction, we found that the particle suspensions in fluid slugs are displaced along the flow directions. The separation performance increases with the increasing flow velocity. The feature of differentiation along the flow directions in our device leads to the result that the separation process can be easily improved by stretching the slug before cutting the slug into pieces. Furthermore, the alternative air slugs between working fluid slugs can also prevent clogging inside the microchannels.