Roshomon (1950) was a unique film in which Kurosawa artistically and elegantly showed perceptions are colored by personal bias. Eyewitness accounts could differ widely. Could it be that we see what we want to see? Or could it be that memory shapes and stores events to suit individual tastes? Elizabeth Loftus, (Professor at the Dept. of Psychology and Social behavior, University of California, Irvine, USA) prefers to use the term "corrupted memory". Her research studies also suggest that human mind is capable of manufacturing memories and holding on to them as real. Memory is not a "one time, one bit information filed and forgotten" It is a dynamic process, and involves reconstruction and reprocessing of data. Many agree with Loftus when she insists that "eyewitness accounts do not run like a video recording", and "an individual's beliefs, desires and imagination can fuel misremembering and information from external sources will exacerbate false recollection".
Having said that it is this very same memory that guides you back home in the evening after a day's hardwork. You never tend to lose the way. The route map is engraved in our memory, from home to school/office/market/busstop/ airport wherever you go, whatever be the distractions enroute, guides you back to home again. Fed up working with inert, dumb materials, scientists asked the question: could we engrave such route maps in materials? Can we enable them to remember and respond? After all biological materials demonstrate intelligence. Why can't we teach a diamond to turn into a lump of graphite and back again when necessary? And why not, after all both diamond and graphite are basically carbon, albeit in different avatars.
Well it is true that we haven't yet reached the diamond-graphite stage yet, but scientists have been able to design other intelligent materials. Shape Memory (SM) materials belong to this class and as the name implies their memory is limited to shapes. They have the ability to switch from a permanent to a temporary form and back again. This switch over could be triggered by a variety of agents: pressure, heat, magnetic field, electricity or light. SM materials have wrought a revolution in frontier technological applications such as space, robotics, bio medicine etc. The simplest and oldest member in this group is perhaps our humble rubber and its capabilities can be easily demonstrated with a common rubber band. Resilience, the ability to accommodate strain without cracking or crumbling, is the key factor for a material to exhibit SM behavior. In polymers, their long chain structure and viscoelasticity are facilitators. In alloys the process is explained through alterations in crystal structure. Nitinol, an alloy of nickel and titanium was the first shape memory alloy to be designed.
So far brittle materials such as ceramics couldn't be trained to remember their shapes because they crumbled under the burden of (memory) strain. But now Li et al have found a way to circumvent that. This collaborative work involves researchers from Massachusetts Institute of Technology, USA and Nanyang Technological University, Singapore. Li et al report their finding in the 27th September issue of Science. Their test material is polycrystalline zirconia with small amounts of intentional impurities such as cerium oxide or yittrium oxide . Zirconia is known to undergo transition from tetragonal to monoclinic form without diffusion. The investigators used micrometer size pillars as test samples as this enabled them to get high surface area at the same time allowed them to keep the volume low. This is a small step leading to a giant leap because ceramics are ideal workhorses for high temperature applications.
References:
1. Misinformation can influence memory for recently experienced highly stressful events
Morgan et al.,International Journal of Law and psychiatry 36, 11-17, 2013
2. Evidence based justice: corrupted memory,
Nature Vol. 500 268-270, Aug. 14, 2013
3. Eyewitness testimony in the Lockerbite bombing case
Elizabeth Loftus Memory, vo.21 584-590, 2013
3.Shape memory and superelastic ceramics at small scales
Lai et al., Science : Vo. 341,1505-1508 , 27 Sept. 2013
Having said that it is this very same memory that guides you back home in the evening after a day's hardwork. You never tend to lose the way. The route map is engraved in our memory, from home to school/office/market/busstop/ airport wherever you go, whatever be the distractions enroute, guides you back to home again. Fed up working with inert, dumb materials, scientists asked the question: could we engrave such route maps in materials? Can we enable them to remember and respond? After all biological materials demonstrate intelligence. Why can't we teach a diamond to turn into a lump of graphite and back again when necessary? And why not, after all both diamond and graphite are basically carbon, albeit in different avatars.
Well it is true that we haven't yet reached the diamond-graphite stage yet, but scientists have been able to design other intelligent materials. Shape Memory (SM) materials belong to this class and as the name implies their memory is limited to shapes. They have the ability to switch from a permanent to a temporary form and back again. This switch over could be triggered by a variety of agents: pressure, heat, magnetic field, electricity or light. SM materials have wrought a revolution in frontier technological applications such as space, robotics, bio medicine etc. The simplest and oldest member in this group is perhaps our humble rubber and its capabilities can be easily demonstrated with a common rubber band. Resilience, the ability to accommodate strain without cracking or crumbling, is the key factor for a material to exhibit SM behavior. In polymers, their long chain structure and viscoelasticity are facilitators. In alloys the process is explained through alterations in crystal structure. Nitinol, an alloy of nickel and titanium was the first shape memory alloy to be designed.
So far brittle materials such as ceramics couldn't be trained to remember their shapes because they crumbled under the burden of (memory) strain. But now Li et al have found a way to circumvent that. This collaborative work involves researchers from Massachusetts Institute of Technology, USA and Nanyang Technological University, Singapore. Li et al report their finding in the 27th September issue of Science. Their test material is polycrystalline zirconia with small amounts of intentional impurities such as cerium oxide or yittrium oxide . Zirconia is known to undergo transition from tetragonal to monoclinic form without diffusion. The investigators used micrometer size pillars as test samples as this enabled them to get high surface area at the same time allowed them to keep the volume low. This is a small step leading to a giant leap because ceramics are ideal workhorses for high temperature applications.
References:
1. Misinformation can influence memory for recently experienced highly stressful events
Morgan et al.,International Journal of Law and psychiatry 36, 11-17, 2013
2. Evidence based justice: corrupted memory,
Nature Vol. 500 268-270, Aug. 14, 2013
3. Eyewitness testimony in the Lockerbite bombing case
Elizabeth Loftus Memory, vo.21 584-590, 2013
3.Shape memory and superelastic ceramics at small scales
Lai et al., Science : Vo. 341,1505-1508 , 27 Sept. 2013
