Could assembled concrete towers be a viable alternative to the steel towers now used for wind turbines?  Could concrete towers be a practical way to raise turbine towers from today’s 80 meters to the steadier winds at 100 meters and taller?  Which of three ways to connect the columns and panels works best for wind turbine towers?  ”We have definitely reached the limits of steel towers,” says Sri Sritharan, Iowa State University engineering professor and leader of the College of Engineering’s Wind Energy Initiative.  ”Increasing the steel tower by 20 meters will require significant cost increases and thus the wind energy industry is starting to say, ‘Why don’t we go to concrete?’”  [Science Daily, 15 May 2013]

Electrodes from the ink-jet printer: Cellulose sheets can be transformed into mesostructured graphene nanostructures by a simple and general method.  Since the iron catalyst can be printed on paper with an ink-jet printer, the products can be prepared with 2D patterns.  Subsequent Cu deposition results in further functionalization of the microstructured electrodes.  [Angewandte Chemie International Edition, 17 JAN 2013]

Tactile sensation is critical for effective object manipulation, but current prosthetic upper limbs make no provision for delivering somesthetic feedback to the user.  For individuals who require use of prosthetic limbs, this lack of feedback transforms a mundane task into one that requires extreme concentration and effort.  Although vibrotactile motors and sensory substitution devices can be used to convey gross sensations, a direct neural interface is required to provide detailed and intuitive sensory feedback.  In light of this, we describe the implementation of a somatosensory prosthesis with which we elicit, through intracortical microstimulation (ICMS), percepts whose magnitude is graded according to the force exerted on the prosthetic finger.  Specifically, the prosthesis consists of a sensorized finger, the force output of which is converted into a regime of ICMS delivered to primary somatosensory cortex through chronically implanted multi-electrode arrays.  We show that the performance of animals on a tactile task is equivalent whether stimuli are delivered to the native finger or to the prosthetic finger.  [IEEE Transactions on Neural Systems and Rehabilitation Engineering, May 2013]

Molten oxide electrolysis (MOE) is an electrometallurgical technique that enables the direct production of metal in the liquid state from oxide feedstock, and compared with traditional methods of extractive metallurgy offers both a substantial simplification of the process and a significant reduction in energy consumption.  MOE is also considered a promising route for mitigation of CO2 emissions in steel-making, production of metals free of carbon, and generation of oxygen for extra-terrestrial exploration.  Until now, MOE has been demonstrated using anode materials that are consumable or unaffordable for terrestrial applications.  To enable metal production without process carbon, MOE requires an anode material that resists depletion while sustaining oxygen evolution.  The challenges for iron production are threefold.  First, the process temperature is in excess of 1,538 degrees Celsius.  Second, under anodic polarization most metals inevitably corrode in such conditions.  Third, iron oxide undergoes spontaneous reduction on contact with most refractory metals and even carbon.  Here we show that anodes comprising chromium-based alloys exhibit limited consumption during iron extraction and oxygen evolution by MOE.  The anode stability is due to the formation of an electronically conductive solid solution of chromium(III) and aluminium oxides in the corundum structure.  These findings make practicable larger-scale evaluation of MOE for the production of steel, and potentially provide a key material component enabling mitigation of greenhouse-gas emissions while producing metal of superior metallurgical quality.  [Nature, 16 May 2013]

Biointegrated electronics have been investigated for various healthcare applications which can introduce biomedical systems into the human body.  Silicon-based semiconductors perform significant roles of nerve stimulation, signal analysis, and wireless communication in implantable electronics.  However, the current large-scale integration (LSI) chips have limitations in in vivo devices due to their rigid and bulky properties.  This paper describes in vivo ultrathin silicon-based liquid crystal polymer (LCP) monolithically encapsulated flexible radio frequency integrated circuits (RFICs) for medical wireless communication.  The mechanical stability of the LCP encapsulation is supported by finite element analysis simulation.  In vivo electrical reliability and bioaffinity of the LCP monoencapsulated RFIC devices are confirmed in rats.  In vitro accelerated soak tests are performed with Arrhenius method to estimate the lifetime of LCP monoencapsulated RFICs in a live body.  The work could provide an approach to flexible LSI in biointegrated electronics such as an artificial retina and wireless body sensor networks.  [ACS Nano, 25 Apr 2013]

Creation of affordable materials for constant release of silver ions in water is one of the most promising ways to provide microbially safe drinking water for all.  Combining the capacity of diverse nanocomposites to scavenge toxic species such as arsenic, lead, and other contaminants along with the above capability can result in affordable, all-inclusive drinking water purifiers that can function without electricity.  The critical problem in achieving this is the synthesis of stable materials that can release silver ions continuously in the presence of complex species usually present in drinking water that deposit and cause scaling on nanomaterial surfaces.  Here we show that such constant release materials can be synthesized in a simple and effective fashion in water itself without the use of electrical power.  The nanocomposite exhibits river sand-like properties, such as higher shear strength in loose and wet forms.  These materials have been used to develop an affordable water purifier to deliver clean drinking water at $2.50/y per family.  The ability to prepare nanostructured compositions at near ambient temperature has wide relevance for adsorption-based water purification.  [PNAS, 21 May 2013]

The self-cleaning function of superhydrophobic surfaces is conventionally attributed to the removal of contaminating particles by impacting or rolling water droplets, which implies the action of external forces such as gravity.  Here, we demonstrate a unique self-cleaning mechanism whereby the contaminated superhydrophobic surface is exposed to condensing water vapor, and the contaminants are autonomously removed by the self-propelled jumping motion of the resulting liquid condensate, which partially covers or fully encloses the contaminating particles.  The jumping motion off the superhydrophobic surface is powered by the surface energy released upon coalescence of the condensed water phase around the contaminants.  The jumping-condensate mechanism is shown to spontaneously clean superhydrophobic cicada wings, where the contaminating particles cannot be removed by gravity, wing vibration, or wind flow.  Our findings offer insights for the development of self-cleaning materials.  [PNAS, 14 May 2013]

Tissue vascularization and integration with host circulation remains a key barrier to the translation of engineered tissues into clinically relevant therapies.  Here, we used a microtissue molding approach to demonstrate that constructs containing highly aligned ‘cords’ of endothelial cells triggered the formation of new capillaries along the length of the patterned cords.  These vessels became perfused with host blood as early as 3 d post implantation and became progressively more mature through 28 d.  Immunohistochemical analysis showed that the neovessels were composed of human and mouse endothelial cells and exhibited a mature phenotype, as indicated by the presence of alpha-smooth muscle actin–positive pericytes.  Implantation of cords with a prescribed geometry demonstrated that they provided a template that defined the neovascular architecture in vivo.  To explore the utility of this geometric control, we implanted primary rat and human hepatocyte constructs containing randomly organized endothelial networks vs. ordered cords.  We found substantially enhanced hepatic survival and function in the constructs containing ordered cords following transplantation in mice.  These findings demonstrate the importance of multicellular architecture in tissue integration and function, and our approach provides a unique strategy to engineer vascular architecture.  [PNAS, 7 May 2013]

We have developed a heat shield based on a metamaterial engineering approach to shield a region from transient diffusive heat flow.  The shield is designed with a multilayered structure to prescribe the appropriate spatial profile for heat capacity, density, and thermal conductivity of the effective medium.  The heat shield was experimentally compared to other isotropic materials.  [arXiv.org, 14 May 2013]

Interconnect is one of the main performance determinant of modern integrated circuits (ICs).  The new technology of vertical ICs places circuit blocks in the vertical dimension in addition to the conventional horizontal plane.  Compared to the planar ICs, vertical ICs have shorter latencies as well as lower power consumption due to shorter wires.  This also increases speed, improves performances and adds to ICs density.  The benefits of vertical ICs increase as we stack more dies, due to successive reductions in wire lengths.  However, as we stack more dies, the lattice self-heating becomes a challenging and critical issue due to the difficulty in cooling down the layers away from the heat sink.  In this paper, we provide a quantitative electro-thermal analysis of the temperature rise due to stacking.  Mathematical models based on steady state non-isothermal drift-diffusion transport equations coupled to heat flow equation are used.  These physically based models and the different heat sources in semiconductor devices will be presented and discussed.  Three dimensional numerical results did show that, compared to the planar ICs, the vertical ICs with 2-die technology increase the maximum temperature by 17 Kelvin in the die away from the heat sink.  These numerical results will also be presented and analyzed for a typical 2-die structure of complementary metal oxide semiconductor transistors.  [arXiv.org, 13 May 2013]