Micromachined plastic W-band bandpass filters

Results are presented for micromachined plastic waveguide bandpass iris filters for W-band applications using a cost-effective polymer micro hot embossing process in conjunction with metallic electroplating and sealing techniques. The prototype filter has an 8-μm thick electroplated gold layer on a polymeric WR-10 waveguide with a 5-cavity Chebyschev-type design. Measurement results show center frequency of 96.77 GHz with a bandwidth of 3.15%, a loaded quality factor 31.73 and an unloaded quality factor for a single cavity resonator is 1210.6, respectively. A minimum insertion loss of −1.22 dB and return loss of better than −9.3 dB have been measured over the entire passband.     

The morphology of limestone-based pellets prepared with kaolin-based binders

Modifications and pelletization of limestone were investigated in order to improve the utilization of CaO-based materials for different catalytic reactions and environmental applications. Attempts to purify the limestone by ion-exchange with CaCl₂ solution did not result in significant removal of impurities. On the other hand, acetification with 10 vol.% acetic acid enhanced pore surface area and pore volume of the sorbent by 42% and 3-fold, respectively. The acetification was found to widen small pores, and thus create a beneficial pore size distribution with more pores in the range of 25–100 nm. In order to utilize such powdered materials in fluidized beds, pelletization is the next step. Unfortunately, pelletization results suggested that natural kaolin is an unsuitable binder for preparing CaO-based pellets due to its negative impact on pellet morphology. By contrast, Al(OH)₃ binder obtained from kaolin leaching had a strong positive effect on the porous texture of the pellets, demonstrated by pore surface area and volume of 22.48 m² g⁻¹ and 0.051 cm³ g⁻¹ for 1 mm pellets with CaO/binder ratio of 5.5, compared to 10.92 m² g⁻¹ and 0.039 cm³ g⁻¹ for natural materials. The enhancement in pellet morphology is mainly attributed to transformation of Al(OH)₃ to the highly porous Al₂O₃ at high temperatures. Pellets synthesized from limestone modified with 10 vol.% acetic acid with Al(OH)₃ binder (ratio of 5.5) exhibited high pore surface area and volume, represented by 1.3-fold and 44% increase over those for natural limestone. It was concluded that the combination of acetified limestone with Al(OH)₃ binder is a promising approach for synthesis of CaO-based pellets with enhanced morphology.     

New approach to gas pressure profile prediction for high temperature AA5083 sheet forming

A new theoretical approach to the prediction of gas pressure profiles that vary smoothly with time in high temperature forming of fine-grained AA5083 sheet is presented. The required pressure-flow stress relationship, which couples the gas pressure profile and the material constitutive model, was implemented in ABAQUS implicit. Forming of a rectangular pan in a die with variable entry radii was simulated with a single creep mechanism model that accounts for hardening/softening in AA5083. Predicted sheet thickness and thinning in a die entry radius region at the end of forming are examined in detail. Results are compared with those from two additional gas pressure schemes. One of these is taken directly from experiments and the other is based upon an algorithm that is internal to ABAQUS. The effect of friction on forming time is explored in the absence of a stability criterion for necking.     

Modified microwave method for the synthesis of visible light-responsive TiO2/MWCNTs nanocatalysts

Recently, TiO₂/multi-walled carbon nanotube (MWCNT) hybrid nanocatalysts have been a subject of high interest due to their excellent structures, large surface areas and peculiar optical properties, which enhance their photocatalytic performance. In this work, a modified microwave technique was used to rapidly synthesise a TiO₂/MWCNT nanocatalyst with a large surface area. X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller measurements were used to characterise the structure, morphology and the surface area of the sample. The photocatalytic activity of the hybrid nanocatalysts was evaluated through a comparison of the degradation of methylene blue dye under irradiation with ultraviolet and visible light. The results showed that the TiO₂/MWCNT hybrid nanocatalysts degraded 34.9% of the methylene blue (MB) under irradiation with ultraviolet light, whereas 96.3% of the MB was degraded under irradiation with visible light.     

Efficient separation scheme for binary mixture of CO2 and H2S using aromatic components

Separating a mixture of CO₂ and H₂S into two products through distillation is both difficult and complicated because of similar relative volatility between the two gasses, particularly when a CO₂ concentration exceeds 80%. Therefore, the separation process can involve many separating stages. However, adding a solvent (agent) to the distillation column during the separation process makes this procedure easier.

In this study, different solvents (ethylbenzene, o-xylene, m-xylene, and toluene) and operating conditions (temperature, pressure, and reflux ratio) for separating CO₂ from H₂S have been simulated through distillation using Aspen HYSYS software. Furthermore, four different aromatic compounds (solvents) for different concentrations (from 0 to 40 mol%) have been evaluated to increase the CO₂/H₂S relative volatility, reducing the quantity of the solvent required and energy consumption.

m-xylene was found to be the best solvent for separating CO₂ from H₂S because of the significant effect on relative volatility, the low quantity required for high CO₂ recovery, and the low energy for generating the solvent.     

Neuroproteomics in neurotrauma

Neurotrauma in the form of traumatic brain injury (TBI) afflicts more Americans annually than Alzheimer's and Parkinson's disease combined, yet few researchers have used neuroproteomics to investigate the underlying complex molecular events that exacerbate TBI. Discussed in this review is the methodology needed to explore the neurotrauma proteome-from the types of samples used to the mass spectrometry identification and quantification techniques available. This neuroproteomics survey presents a framework for large-scale protein research in neurotrauma, as applied for immediate TBI biomarker discovery and the far-reaching systems biology understanding of how the brain responds to trauma. Ultimately, knowledge attained through neuroproteomics could lead to clinical diagnostics and therapeutics to lessen the burden of neurotrauma on society.     

A study of hardware-friendly methods for gradient domain tone mapping of high dynamic range images

A large class of techniques for image processing is based on manipulation of the gradient field of an image. These techniques have high computational complexity, due to the need to solve an inverse problem, taking the form of a Poisson equation, to find the output image that best matches a manipulated gradient field. This work studies hardware-friendly techniques, appropriate for implementation on a field-programmable gate array implementation and embeddable inside a camera, for approximating this solution. Fattal’s operator for the dynamic range compression of high dynamic range images is studied as a representative example application. A family of methods, inspired by Fattal’s operator but with significantly lower computational complexity, solves the inverse problem in a moving window of small size. In this paper, a study is conducted to understand the role that the boundary conditions and the size of the window play in the quality of the resulting output image and the size of the hardware. The impact of using single-scale and multi-scale approaches to compute the attenuation factors needed for Fattal’s operator is also considered.     

An approach to monitor the real-time deformation during heat treatment of 3D-printed glass

This study suggests a tool for a better control on the sintering/crystallization of 3D-printed bioactive glass-ceramics bodies. A small cantilever in form of a bar with square cross section attached to a base and inclined 34° with the horizon, was used to monitor the viscous flow and sintering/crystallization headway of a glass-ceramic systems. 3D printing and sintering of bioactive glass-ceramics is of great interest for medical care applications. Viscous flow ensures sufficient densification of the typically low density printed green bodies, while crystallization prevents the structure from collapsing under the gravitational load. As a model system, a bioactive glass called BP1 (48.4 SiO₂, 1 B₂O₃, 2 P₂O₅, 36.6 CaO, 6.6 K₂O, 5.6 Na₂O (mol%)), which has a chemical composition based on that of ICIE16, was employed in this work. In addition, ICIE16 was used as a reference glass. The results show that the suggested design is a very promising tool to track the real-time deformation of 3D printed glass-ceramic specimens and gives a good indication for the onset of crystallization as well.     

Magnetic and Photocatalytic Activity of Pure BaFe12O19 and BaFe12O19-TiO2 Hexagonal Ferrite Nanocomposites

Journal of Superconductivity and Novel Magnetism - Hard hexagonal barium ferrite BaFe12O19 (BaM), as well as core–shell structure BaFe12O19-TiO2 composite nanoparticles, was successfully...     

PILOT PLANT STUDIES AND MODELLING OF A SEMI-BATCH POLYESTERIFICATION PROCESS

A novel unsaturated polyester formulation was developed recently in our laboratories. The polyester resin, which was designed as a green-house glazing material, exhibited excellent optical properties and superior resistance to weathering conditions. This study describes the scale-up procedure followed in preparing the resin in a 200 L pilot plant reactor starting from its preparation in a 1 L reactor. The paper analyzes the major variables affecting the polyesterification process and presents a semi-empirical model capable of predicting the pilot plant kinetic data from laboratory reactor data. The model is based on a recently developed third order kinetic equation for the reaction of non-stoichiometric amounts of hydroxyl and carboxylic groups. The model quantifies the effects of reaction temperature and inert gas flow rate on reaction rate and provides a basis for the polyesterification process scale-up. The reaction temperature dependence is assumed Arrhenius, whereas the gas flow rate dependence is empirically determined as a function of the molar ratio of reactants to inert gas. Application of the model to commercial sized reactors will be highlighted.