Variability in nanometer CMOS: Impact, analysis, and minimization

Variation is a significant concern in nanometer-scale CMOS due to manufacturing equipment being pushed to fundamental limits, particularly in lithography. In this paper, we review recent work in coping with variation, through both improved analysis and optimization. We describe techniques based on integrated circuit manufacturing, circuit design strategies, and mathematics and statistics. We then go on to discuss trends in this area, and a future technology outlook with an eye towards circuit and CAD-solutions to growing levels of variation in underlying device technologies.     

Plant-level maintenance decision support system for throughput improvement

In the current global scenario of extreme competition, factors such as productivity, availability, quality and cost of operations play a vital role in the success of a company. A critical component relating to all of the above is maintenance. The conventional maintenance decision support systems have primarily focused on maximising the gains of a single machine system. However, a real life application usually consists of multiple machines, and the operational level decisions are more complex. In this paper, an on line plant-level maintenance decision support system (PMDSS) is developed by combining the short term and long term decision making process to improve the overall system performance while continuously attempting to maximise immediate profits in the short term. The PMDSS works towards two basic aims: (1) unplanned downtime reduction by predicting the remaining useful life of the machines, and (2) efficient utilisation of the finite maintenance and production resources through identifying the throughput-critical machines. The benefits of this approach are presented by considering an industrial case study of an automotive assembly line. The results obtained using this PMDSS approach shows a big throughput improvement as compared to the conventional maintenance policies.     

Synaptic electronics and neuromorphic computing

In order to map the computing architecture and intelligent functions of the human brain on hardware, we need electronic devices that can emulate biological synapses and even neurons, preferably at the physical level. Beginning with the history of neuromorphic computation, in this article, we will briefly review the architecture of the brain and the learning mechanisms responsible for its plasticity. We will also introduce several memristive devices that have been used to implement electronic synapses, presenting some important milestones in this area of research and discussing their advantages, disadvantages, and future prospects.     

Coherent Spin Transport and Suppression of Spin Relaxation in InSb Nanowires with Single Subband Occupancy at Room Temperature

A longstanding goal of spintronics is to inject, then coherently transport, and finally detect electron spins in a semiconductor nanowire in which a single quantized subband is occupied by the electrons at room temperature. Here, the achieving of this goal in electrochemically self‐assembled 50‐nm diameter InSb nanowires is reported and substantiated by demonstrating both the spin‐valve effect and the Hanle effect. Observing both effects in the same sample allows one to estimate the electron mobility and the spin relaxation time in the nanowires. It is found that despite four orders of magnitude degradation in the mobility compared to bulk or quantum wells and a resulting four orders of magnitude increase in the Elliott‐Yafet spin relaxation rate, the spin relaxation time in the nanowires is still about an order of magnitude longer than what has been reported in bulk and quantum wells. This is caused by the elimination or suppression of the D’yakonov‐Perel’ spin relaxation through single subband occupancy. These experiments shed light on the nature of spin transport in a true quantum wire and raise hopes for the realization of a room‐temperature Datta‐Das spin transistor, where single subband occupancy is critical for optimum performance.     

Detection of organophosphorus compounds by covalently immobilized organophosphorus hydrolase

As a consequence of organophosphorus (OP) toxins posing a threat to human life globally, organophosphorus hydrolase (OPH) has become the enzyme of choice to detoxify such compounds. Organophosphorus hydrolase was covalently immobilized onto a quartz substrate for utilization in paraoxon detection. The substrate was cleaned and modified prior to chemical attachment. Each modification step was monitored by imaging ellipsometry as the thickness increased with each modification step. The chemically attached OPH was labeled with a fluorescent dye (7-isothiocyanato-4-methylcoumarin) for the detection of paraoxon in aqueous solution, ranging from 10(-9) to 10(-5) M. UV-visible spectra were also acquired for the determination of the hydrolysis product of para-oxon, namely p-nitrophenol.     

Wetting behavior of polymer coated nanoporous anodic alumina films: transition from super-hydrophilicity to super-hydrophobicity

We show that nanoporous anodic alumina films, with pore diameters in the range 10-80 nm, can be transformed from being very hydrophilic (or super-hydrophilic) to very hydrophobic (or super-hydrophobic) by coating the surface with a thin (2-3 nm) layer of a hydrophobic polymer. This dramatic transformation happens as a result of the interplay between surface morphology and surface chemistry. The coated surfaces exhibit 'sticky' hydrophobicity as a result of ingress of water into the pores by capillary action. The wetting parameters (contact angle and contact angle hysteresis) exhibit qualitatively different dependences on pore diameters in coated and uncoated films, which are explained by invoking appropriate models for wetting.     

Threshold Switching of Ag or Cu in Dielectrics: Materials,Mechanism, and Applications

Threshold switches with Ag or Cu active metal species are volatile memristors (also termed diffusive memristors) featuring spontaneous rupture of conduction channels. The temporal dynamics of the conductance evolution is closely related to the electrochemical and diffusive dynamics of the active metals which could be modulated by electric field strength, biasing duration, temperature, and so on. Microscopic pictures by electron microscopy and quantitative thermodynamics modeling are examined to give insights into the underlying physics of the switching. Depending on the time scale of the relaxation process, such devices find a variety of novel applications in electronics, ranging from selector devices for memories to synaptic devices for neuromorphic computing.     

Uptake of hydroxocobalamin by rat liver mitochondria. Binding to a mitochondrial protein

Lysosome-free preparations of rat liver mitochondria take up hydroxo[57Co]cobalamin by a process which is dependent on mitochondrial swelling, rather than on energy or ion fluxes. The uptake system is saturable and unidirectional, leading to inside/outside concentration ratios of 17. The process also exhibits specificity: cyano[57Co]cobalamin is taken up less rapidly and to a lesser extent than hydroxocobalamin; methylcobalamin and adenoslcobalamin inhibit hydroxocobalamin uptake markedly, while cyanocobalamin does not. The [57Co]cobalamin ([57Co]Cbl) taken up is bound to a mitochondrial protein whose apparent molecular weight is 120,000 by Sephadex G-150 chromatography. Double reciprocal plots of bound [57Co]Cbl versus medium [57Co]Cbl concentration yield estimates for bound Cblmax of 29 pmol/mg of protein and for Kd is 8.2 muM. We conclude that mitochondrial uptake of cobalamins occurs via the diffusion of free cobalamins into the mitochondria and their subsequent binding to a high affinity mitochondrial protein(s) which we propose to be the source of the unidirectional character, the saturability, and the specificity of the uptake system.