title: Influence of powder forging and heat treatment conditions on the properties of the cost-effective Ti-5Al-2.5Fe alloy

authors: Bolzoni, Leandro

abstract: The Ti-5Al-2.5Fe alloy is a cheaper α+β Ti alloy with mechanical performance comparable to those of the Ti-6Al-4V alloy whose cost could be further reduced by producing it via powder metallurgy. In this study, the effect of the thermomechanical deformation temperature on the properties of the Ti-5Al-2.5Fe alloy produced from elemental powders was studied. Furthermore, the effect of the modification of the microstructure via heat treatments on the properties of the forged billets was analysed. This study demonstrates that powder forging can successfully be used to manufacture α+β Ti alloys and the selection of the forging temperature significantly affects the mechanical behaviour, where the lower the forging temperature the stronger and the less ductile the material. The post-processing via solution treatment plus aging generally improves the mechanical properties of the Ti-5Al-2.5Fe alloy, especially in terms of ductility, without compromising the strength.

text: Influence of powder forging and heat treatment conditions on the properties of the cost-effective Ti-5Al-2.5Fe alloy The Ti-5Al-2.5Fe alloy is a cheaper α+β Ti alloy with mechanical performance comparable to those of the Ti-6Al-4V alloy whose cost could be further reduced by producing it via powder metallurgy. In this study, the effect of the thermomechanical deformation temperature on the properties of the Ti-5Al-2.5Fe alloy produced from elemental powders was studied. Furthermore, the effect of the modification of the microstructure via heat treatments on the properties of the forged billets was analysed. This study demonstrates that powder forging can successfully be used to manufacture α+β Ti alloys and the selection of the forging temperature significantly affects the mechanical behaviour, where the lower the forging temperature the stronger and the less ductile the material. The post-processing via solution treatment plus aging generally improves the mechanical properties of the Ti-5Al-2.5Fe alloy, especially in terms of ductility, without compromising the strength.

year: 2023-01-01

title: Electrical Conductivity of Brain Cortex Slices in Seizing and Non-seizing States

authors: Elbohouty, Maher

subjects: Electrical Conductivity

abstract: The electrical conductivity of thin living slices of mouse cerebral cortex is measured. Two only out of fifteen different attempting ways were effective. I have successfully measured the electrical conductivity of mouse brain cortex in seizing and non-seizing conditions. The first successful approach is called 	the van der Pauw method, where four silver-silver chloride cylindrical wire electrodes were immersed in full length at the corners of the sample. The second is a one-dimensional technique where two flat electrodes were placed on either face of the 400 micrometer thick samples.

In both methods the electrodes were connected to an Agilent E4980A impedance monitor. The conductivity at 10 kHz of each sample was calculated based on measurements of injected current and potential difference between electrodes. Both approaches were validated by measuring electrical conductivities of known solutions. There were two main challenges: the small size of the sample and keeping it alive. I overcame these challenges by suitable electrodes and fast measuring equipment (Agilent E4980A LCR meter). For the one-dimensional technique I also measured the conductivity across the frequency range 20 Hz to 2 MHz.

The results consistently show the mean conductivity of seizing brain tissue is significantly lower than that of non-seizing tissue at 10 kHz. Also, the conductivity of seizing slices is lower than the conductivity of non-seizing slices over the frequency range 20 Hz to 2 MHz. 

These results suggest a link between electrical conductivity and seizure activity. I have not investigated the causes of these differences but explanations consistent with the literature are a change in chemical environment during seizure or a reduction in gap junction connectivity.

text: Electrical Conductivity of Brain Cortex Slices in Seizing and Non-seizing States The electrical conductivity of thin living slices of mouse cerebral cortex is measured. Two only out of fifteen different attempting ways were effective. I have successfully measured the electrical conductivity of mouse brain cortex in seizing and non-seizing conditions. The first successful approach is called 	the van der Pauw method, where four silver-silver chloride cylindrical wire electrodes were immersed in full length at the corners of the sample. The second is a one-dimensional technique where two flat electrodes were placed on either face of the 400 micrometer thick samples.

In both methods the electrodes were connected to an Agilent E4980A impedance monitor. The conductivity at 10 kHz of each sample was calculated based on measurements of injected current and potential difference between electrodes. Both approaches were validated by measuring electrical conductivities of known solutions. There were two main challenges: the small size of the sample and keeping it alive. I overcame these challenges by suitable electrodes and fast measuring equipment (Agilent E4980A LCR meter). For the one-dimensional technique I also measured the conductivity across the frequency range 20 Hz to 2 MHz.

The results consistently show the mean conductivity of seizing brain tissue is significantly lower than that of non-seizing tissue at 10 kHz. Also, the conductivity of seizing slices is lower than the conductivity of non-seizing slices over the frequency range 20 Hz to 2 MHz. 

These results suggest a link between electrical conductivity and seizure activity. I have not investigated the causes of these differences but explanations consistent with the literature are a change in chemical environment during seizure or a reduction in gap junction connectivity.

year: 2013

title: Te Kahautu Maxwell  | Te Matatini Mātaatua representative [Interviewed by Dale Husband]

authors: Maxwell, Te Kahautu

abstract: This weekend in the Bay of Plenty, twenty-two kapa haka teams, including the reigning Te Matatini winners, showcased some of the nation’s best kapa haka performers during the Mātaatua senior regional tournaments.

text: Te Kahautu Maxwell  | Te Matatini Mātaatua representative [Interviewed by Dale Husband] This weekend in the Bay of Plenty, twenty-two kapa haka teams, including the reigning Te Matatini winners, showcased some of the nation’s best kapa haka performers during the Mātaatua senior regional tournaments.

year: 2024