Post Baking Research Articles

Digital Luminescence Patterning via Inkjet Printing of a Photoacid Catalysed Organic-Inorganic Hybrid Formulation.

Accurate positioning of luminescent materials at the microscale is essential for the further development of diverse application fields including optoelectronics, energy, biotechnology and anti-counterfeiting. In this respect, inkjet printing has recently attracted great interest due to its ability to precisely deposit with high throughput and no contact, functional materials on different types of substrates. Here, we present a novel photoacid catalysed organic-inorganic hybrid luminescent ink. The formulation, containing monomers bearing epoxy and silane functionalities, a photoacid generator and a small percentage of Rhodamine-B, shows good jetting properties and adequate wetting of the deposited droplets on the receiving substrates. Ultraviolet exposure of the deposited material triggers the cationic ring-opening polymerization reaction of the epoxy groups. Concomitantly, if atmospheric water is available, hydrolysis and condensation takes place, overall leading to a luminescent crosslinked hybrid organic-inorganic polymeric material obtained through a simple one-step curing process, without post baking steps. Advantageously, protection of the ink from actinic light delays the hydrolysis and condensation conferring long-term stability to the ink. Digital patterning leads to patterned emissive surfaces and elements with good adhesion to different substrates, mechanical and optical properties for the fabrication of optical and photonic elements and devices.

Design of novel photobase generators upon violet LEDs and use in photopolymerization reactions

Two new near-UV and visible-light-sensitive photobase generators (PBGs) are synthesized and investigated. They are built on a near-UV and visible light sensitive (E)-3-(2,2′-bithiophen-5-yl)-2-cyanoacrylic acid chromophore and a latent strong base such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Upon irradiation, decarboxylation occurs and the base is released. The anionic curing of epoxy/thiol as well as thiol/divinylsulfone formulations in the presence of these PBGs under LEDs at 385 and 405 nm is studied. More than 60% of conversion of the thiol and epoxy functions is achieved upon LED@385 nm without any post baking.

Investigation of the Effect of Dielectric Properties of the Biscuit on RF Power Uniformity using a Finite Element Computer Model

Background: Biscuit baking process is a major energy consuming and quality deciding process. In conventional biscuit baking process which rely on conduction, convection, radiation mode of heat transfer a condition called checking arises. Checking arises due to the build-up of stresses in the product being heated. The cause for the stresses is the differential moisture content between the outer surface and the centre bone of the biscuit and causes cracking of biscuit. Radio Frequency (RF) Post Baking is a proven solution to this problem. But the wide scale industrial use of RF post baking of biscuits is limited by energy efficiency and cost of the RF heating system. Energy efficiency can be improved by having better RF power uniformity/heating uniformity in the sample (biscuit) being RF heated. The uniformity of radio frequency power distribution defined by a metric called Power Uniformity Index (PUI) is used to evaluate the efficiency of the radio frequency heating. Methods: A finite element computer model of the RF heating system for post baking biscuits with staggered electrode configuration was developed using comsol multiphysics software. The dielectric properties of biscuit were varied from a scale of 0 till 80 and its effect on the RF power distribution and hence the heating uniformity in radio frequency post baking of was observed. Findings: The simulation results obtained indicate that the dielectric properties of the sample (biscuit) do have significant effect on RF power distribution and hence the heating uniformity when the values of dielectric constant and loss factor are lower than 10. Application: The results obtained give an insight into the effect of dielectric properties of biscuit on the RF power distribution in RF dielectric heating of biscuits.

Adsorption Model of Organic Molecules on the Surface of Thermally Oxidized Silicon

Ethanol adsorbed on the surface of a thermally grown oxide was analyzed using X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurements. Ethanol is slightly adsorbed and then easily desorbed by post baking on as-grown thermal oxide, while the ethanol adsorbed on the thermal oxide after pre baking is not desorbed by post baking. More ethanol molecules are adsorbed on a chemical oxide than on a thermal oxide. When the thermal oxide is slightly etched, more ethanol is adsorbed. OH groups may not presence on as-thermally-grown oxide, but will be generated by etching the surface of the thermal oxide. The relative amount of OH groups on the various surfaces of the thermal oxide was discussed.

Investigation of Atmospheric Pressure CVD‐Produced Aluminum Coatings for the Protection of Steel from Corrosion

AbstractThis study investigates the use of atmospheric pressure (AP)CVD‐produced aluminum (Al) coatings for the protection of steel from corrosion. Coatings produced through thermal decomposition of a triisobutylaluminum (TIBAL)‐based precursor at 548 and 573 K are shown to exhibit growth rates of 0.5 and 1.1 µm min−1, respectively. Glow discharge optical emission spectroscopy (GDOES) reveals that, in the main, the coatings consist of pure Al with oxygen present as a minor constituent. Results of the structural, morphological, electrical, and mechanical characterization reveal that the APCVD Al coatings exhibit a face center cubic (fcc) structure with no preferred orientation, a non‐columnar grain structure with grain size ranging from 3 to 10 µm, and a surface roughness close to 2 µm. Such coatings are also shown to offer an electrical resistivity of 3.5 µΩ·cm, a density of 2.60 g cm−3, and an adhesive strength of 703 kg cm−2. Cross‐sectional examination of coated samples indicate that the APCVD process can yield excellent step coverage and throwing power. Hydrogen embrittlement (HE) tests reveal that Al‐coated bars with no post baking experience premature failure due to the presence of incorporated reaction product, hydrogen, in the steel substrate. Samples post‐baked at 463 K for 23 h to remove the hydrogen from the substrate are shown to withstand the load for as long as 202 h. Corrosion studies conducted using potentiodynamic polarization measurements, electrochemical impedance spectroscopy, and salt fog tests show that the corrosion resistance of the APCVD Al coatings is comparable to that of pure Al foils, and that such coatings provide acceptable sacrificial protection for steel substrates.

Fabrication of spiral-shaped microfluidic channels in glass by femtosecond laser

Long spiral-shaped microfluidic channels in glass have been fabricated by femtosecond laser direct writing. After hydrofluoric acid etching and post baking, the laser modified regions in glass formed hollow microstructures. The diameter size and the screw-pitch of the channels can be set freely. The experimental results showed that the etched internal surface of the microchannel by hydrofluoric acid will become smoother after the subsequent baking. The incident laser power and scanning speed can also influence the channel quality.

Bread baking does not enhance the bioavailability of hydrogen reduced iron powder

Elemental iron powders, widely used to fortify flour and cereal products, typically have relative biological values of ~50% compared to FeSO4. Our objective was to test the hypothesis that bread baking enhances the bioavailability of elemental iron powders by oxidizing elemental iron (Fe0) to Fe2+or Fe3+. Methods Bread baked with flour fortified with either hydrogen reduced (HR) Fe or FeSO4 (300 mg Fe/kg flour), or no added iron, was dried and milled. Diets contained 35% bread, 35% ground corn, 22% whey protein isolate, a mineral/vitamin premix, and 130 mg Fe/kg. A hemoglobin repletion assay with weanling, iron deficient piglets was used to assess bioavailability. Experiment 1 Crossbred piglets (Hampshire x Landrace x Yorkshire) were divided into two groups and fed diets containing bread fortified, pre-baking, with either FeSO4 or HR Fe. After 16 days, hemoglobin repletion efficiencies (HRE) in the piglets fed HR and FeSO4 fortified breads were 14.9% & 30.9%, respectively (p<0.001). Experiment 2 Similar to experiment 1 except a 3rd treatment consisting of unfortified bread with HR Fe added post-baking was included. After 14 days, HREs in piglets fed the unfortified bread plus HR Fe added post baking, HR Fe fortified bread, and FeSO4 fortified bread, were 6.6%, 8.9%, & 16.1%, respectively. HRE in the FeSO4 group was significantly higher but the 2 HR Fe groups were not different. We conclude that bread baking does not enhance the bioavailability of HR iron powders. Funded by College of Agriculture and Life Sciences, Cornell University.

Direct fabrication of freely movable microplate inside photosensitive glass by femtosecond laser for lab-on-chip application

We demonstrate the fabrication of complicated three-dimensional (3D) microstructures embedded in a photosensitive glass by a high-order multiphoton process using a femtosecond (fs) laser. Direct writing of the fs laser followed by a post baking process and preferential etching in a dilute hydrofluoric (HF) acid solution results in a microplate that can freely move in hollow structures embedded in the glass. The fabricated structure functions as a microvalve that can control the flow direction of fluids in the microreactor.

Effects of Molecular-Weight Distributions of Resist Polymers and Process Control on Lithography for 0.1.MU.m and Below.

We describe how molecular-weight distributions of resist polymers and process control affect lithography for 0.1μm and below, especially for negative-type resists. There are two main issues for precise critical dimension (CD) control and high resolution in the region: microscopic pattern fluctuation caused by ultrasmall edge roughness in fabricated resist patterns (nano edge roughness); and pattern-size change due to acid diffusion in chemical amplification resists. We have found that nano edge roughness and acid diffusion can be suppressed by controlling the molecular-weight distributions of the base matrix polymers. It is also quite important to control process conditions to achieve high pattern fidelity with molecular-controlled resist materials. Multi-step post baking was applied to minimize the resist pattern deformation before dry etching. We have found that this process can suppress pattern size variations to within 10nm.