The close of 2013 gives us an excellent opportunity, though satiated with holiday feasts, to look back on a year that has been filled with scientific accomplishment. So it's time to get comfortable on your Binary Chair, sip your hot cocoa from a phase-change mug while your Foodini prints out a batch of cookies and reflect on science stories of note from the past year.

Printing ourselves

If 2012 was the year of 3D printing, 2013 marked the first real progress in printing bits of lifeforms.

We have seen the printing of retinal cells in a major step toward growing replacement retinas, as well as the 3D printing of functional liver tissue.

New methods for printing tissues included the direct printing of hydrogel blood vessel scaffolding by dynamic optical projection stereolithography, 3D printing of human embryonic stem cells, and the micro 3D printing of lipid cell-like assemblies as tissue substitutes. On the nanoscale, we have seen the creation of artificial ribosomes, which carry out biological protein synthesis in the body.

Also of note is the development of the BioPen, which allows a surgeon to directly draw stem cells, scaffolding, and growth factors on the damaged surfaces of bones, thereby assisting their rapid healing.

We confidently expect printing bits and pieces of ourselves for replacement and medical research will continue as a hot topic throughout the decade, with substantial new treatments hitting the medical mainstream as we approach 2020. The maximum human longevity probably won’t be radically changed, but somewhat longer and much healthier lives are likely to be the fallout from the medical use of replacement organs.

Stem cells, replacement tissues, and mini-organs

A topic closely related to 3D printing of people parts is enabling a flexible source of the cells and tissues needed for such procedures. 2013 was a year of great progress in this area, with developments ranging from creation of mini-brains to a potential cure for baldness.

Here’s a short list of various types of cells, tissues, and organs researchers have succeeded in growing in 2013:

The real question remaining after this year: Is there any type of cell or tissue we can’t figure out how to produce? We suspect that until medicine is able to substantially duplicate the contents of a brain, or some smoothly operating cerebral rejuvenation treatment comes along, 120 years will continue to be roughly the maximum human lifespan. However, we can still have hair at age 120! Many of these new methods are awaiting FDA approval for human testing, so in the short term you might still want to go ahead and get yourself a good toupée!

Super strong materials

2013 has seen major strides in practical, experimental, and theoretical terms, toward stronger materials and slipperier surfaces.

Not surprisingly, graphene retains its crown as the strongest material that has actually been made in significant amounts. A new technique for making large areas of polycrystalline graphene has succeeded in reproducing the record strength of single crystal graphene. Graphene aerogel has also retaken the position of world’s lightest solid with a density of 0.16 mg/cc, or about one-eighth of the density of air.

Carbon nanotubes, which are rolled-up cylinders of graphene, have successfully been spun into hundreds of meters of ≈10 micron diameter cable with mechanical, electrical, and thermal properties on a par with very short nanotubes made with alternate approaches.

Closer to immediate application are artificial spider silk and a carbon fiber and polymer cable called UltraRope. UltraRope is intended to extend the reach of elevators beyond the 500 meter limit of steel cable. Kone (UltraRope’s manufacturer) is only claiming that 1 km elevators will be made possible by UltraRope, but a quick analysis of strength to weight ratios suggests that the free breaking length of UltraRope is in the neighborhood of 300 km – about seven percent of that required for use in a space elevator. UltraRope is currently being used in a skyscraper at the Marina Bay Sands integrated luxury resort in Singapore.

In a significant theoretical development, the properties of a one-dimensional carbyne chain have been calculated. A perfect carbyne chain is found to be about 30 percent stronger and stiffer than a perfect sheet of graphene. However, the devil is in the detail. The longest carbyne chain yet synthesized had a length of only 44 atoms, or about 5 Angstroms. Also, it is likely that neighboring carbyne chains will cross-link into a tarry polymer.

The advancing properties and manufacturability of strong materials are bringing more applications into reach, from better surgical materials and bulletproof vests to auto parts such as the carbon fiber passenger cell of the new BMW i3 electric car. In the near term, lighter weight generally correlates with energy savings, whether in operation or construction, and precision machining depends fundamentally on tough, stiff, high strength materials. At some point, entirely new applications in areas such as nanoelectronics and (we hope) the aforementioned space elevator arena will appear when the cost and availability of these new materials are more favorable.

Up the slippery slope

Non-adherent surfaces have improved by leaps and bounds in 2013. On the market this year is Ultra-Ever Dry, a new product of UltraTech, an environmental compliance company in Florida. Ultra-Ever Dry works by forming a nanostructured surface when it dries on a primer coat, creating huge numbers of tiny gaps that trap and hold air. As a result, water droplets only touch 2-3% of the low surface area coating, while the rest of the water droplet remains surrounded by the trapped air. These elements render Ultra-Ever Dry superhydrophobic as well as oleophobic for refined oils. And the potential applications of these types of materials don't stop there. Researchers at the University of Freiburg, for example, have created a similar nanostructure on a surface to prevent insects from getting a secure foothold.

Last year, Professor Joanna Aizenberg at Harvard developed Slippery Liquid-Infused Porous Surfaces (SLIPS) – the slipperiest synthetic surface known. This year significant extensions of the basic idea have emerged including the creation of a stable, ultrasmooth, lubricant layer by filling a nanoporous surface with a water-immiscible liquid which locks the liquid in place. A similar surface has also been made by engineers at the University of Michigan.

Aizenberg's group also found that if the nanoporous surface were made on an elastic material, the surface could be stretched, increasing its area and making the liquid layer thinner. When the liquid layer becomes sufficiently thin, the nanoporous surface begins to stick out of the liquid, and the surface stops being slippery. This switch of surface slipperiness can be made many times, simply by stretching and releasing the elastic. Aizenberg’s lab has also developed a coating in which the nanoporous surface is made of glass.

While one of the prime areas for use of slippery surfaces is in self-cleaning materials, they also hold promise in fields such as chemical engineering, where such materials could be used to selectably direct reactants within a processing assembly, or separate incompatible reaction products ... and let's not forget the prospect of replacing water slides with airy nothings!

Ghost in the machine: Brain-computer interfaces

Reference to the "ghost in the machine" was philosopher Gilbert Ryle's metaphor through which he indicated his fundamental disagreement with mind-body dualism. Now, however, technology has almost brought us to the point where each of us can be the ghost (mind) controlling a real-world machine.

The first example up is that of a pair of monkeys at Duke University who have learned to control the arms of a virtual monkey strictly through their thoughts. The monkeys were implanted with electrodes capable of recording roughly 500 individual signals from the motor cortex, the supplementary motor area, and the primary somatic sensory cortex, these being the regions of the brain associated with movement and movement feedback. These signals were then used as the basis for controlling a computer avatar, which took the form of two arms of a monkey, displayed from a first-person perspective.

Also of note is the achievement of researchers at the University of Minnesota who used signals derived from a 64-electrode EEG skullcap to direct the flight of a quadcopter. Subjects operated the quadcopter with high precision by opening and closing their fists to generate neuronal signals in the motor cortex which were picked up by the EEG system. Such demonstrations are huge steps toward applying BCIs to prosthetics and sensory augmentation.

On the slightly more eccentric side of brain-computer interface applications sits the prototype Neurowear Neurocam. This assistant for the hopelessly self-involved includes an integrated iPhone5, and is worn on the head. When the operator sees something of interest, an EEG sensor detects that interest, and automatically takes a 5-second animated GIF. (I know – why a GIF if you are carrying around a 8 MP iPhone camera?) so you can can review what caught your interest during the day.

Lasers beam in

Lasers have occupied a prime position in our technological development for quite some time, and 2013 is no exception. The military still wants to shoot things with lasers, and some laser weapons are going into limited service. Telecommunications still depend on lasers, and data links have now been demonstrated from Earth to Lunar orbit. Let's take such applications as givens, and take a look at some of the less highly touted advances in this field made throughout the year.

Perhaps the most extreme transition from theory to practice in 2013 was the demonstration of a laser-driven particle accelerator at the SLAC National Accelerator Laboratory in the US. In this first demonstration of the acceleration principle, a 400 micron long grating made of fused quartz was excited by pulses from a picosecond laser. This set up an oscillating electric field within the grating that successfully accelerated 60 MeV electrons. While the demonstration only added about 100 keV to the energy of the electrons, the rate of acceleration was about ten times larger than possible in conventional accelerators. It is possible in principle to ramp such laser-driven accelerators up to the level where an accelerator having the energy of the Large Hadron Collider could fit inside a handball court.

Another sign of progress (you decide in what direction) is the licensing of a laser uranium isotope enrichment plant by the US Nuclear Regulatory Commission. While it is too early to tell when (and if) the plant will actually be built, that it has come this far suggests that this long-studied process is about ready to join the world.

Another new use for lasers is in medicine, where ruptured intestines are being sealed by laser welding and a gold-based solder. Developed using pigs as subjects, the welds resulted in leakproof and rather robust repairs. While it's all a bit queasy, this research may well result in the saving of lives by preventing infection from re-perforation of a patient's intestines.

On a more light-hearted note, Amanda Ghassael has used a commercial laser cutter (an Epilog 120 Watt Legend EXT) to cut old-fashioned records in maple, acrylic, and paper discs. Unfortunately for such a cool idea, the sound quality is pretty bad (estimated at 4-5 bits at a 4.5 kHz sampling rate).

You are what you eat

This year has seen Gizmag cover our share of unusual food sources, including Soylent, an overgrown protein shake being developed as a food substitute (I just can't call it food) for busy people who hate taking time out to eat.

2013 also saw the advent of the first lab-grown burger. This delicacy was grown as a culture of bovine muscle cells which were then bound together into a patty with salt, egg powder, bread crumbs, red beet juice, caramel, and saffron. In the end, reports indicate that the bogus burger had an appropriate texture, but suffered in the taste department. As any chef could have attested, meat without fat is downright dull in flavor. Despite this, there seems to be little effort being applied to the problem of growing edible fats.

And for dessert? Why not try glow-in-the-dark ice cream. The glow is the result of including a green luminescent protein into the delectable dessert. The protein was originally derived from jellyfish, but a synthetic version was used to turn on the ice cream. Its luminescence is triggered by the calcium in the ice cream and by agitation, so each lick of the cone is accompanied by a rich green glow.

Among the dicier food products of the year were Selfmade cheeses, which are produced using human bacteria. Each Selfmade cheese is created from cultures derived from samples taken from people's armpits, toes, and noses. The result is autologous fromage unique to each donor. Selfmade cheese is not intended for human consumption, but it seems likely that someone has tasted their cheese in the interest of science. Do you suppose it will be considered rude to sample someone else's cheese without asking permission?

Standard Models keep on keeping on

In physics this year, both the Standard Model of particle physics (SMPP) and the Standard model of cosmology (SMC) were tested in a number of ways in a search for new physics.

In particle physics, the first measurement of the proton's weak charge (the weak interaction analog of electric charge) was in good agreement with the predictions of the SMPP. An improved experiment that sought to measure the shape of an electron established that they are spherical to better than about 10^-28 cm, consistent with the SMPP.

The hunt for dark matter continued with the new LUX experiment in South Dakota. Unfortunately this found nothing despite a tenfold increase in sensitivity compared to earlier experiments.

These results may not be as exciting as a left-field discovery, but they are of great importance because they restrict the possible forms of new physics. For example, the electron shape measurement is sufficiently accurate to rule out certain varieties of new physics that predict stronger time-reversal symmetry violations than are possible in the Standard Model. The LUX result essentially rules out various hints of dark matter, and puts rather strong constraints on dark matter candidates. Still, as there is no particular reason to believe that the LHC, when it comes back on line at 13 TeV, will find signs of new physics, carrying out complementary (and much cheaper) experiments will continue to be a fruitful direction for particle physics.

On the cosmology front, we have found that Einstein's cosmological constant does a better job of describing the observational effects attributed to "dark energy" than any of the more detailed models. A new study of the compositional proportions of lithium isotopes in the early Universe is in excellent agreement with the SMC, removing what appeared to be a disagreement between predictions based on a Big Bang cosmology and earlier observations now known to be flawed.

Just to keep things interesting, however, the latest Planck map of the cosmological microwave background confirms earlier hints that the 370,000 year old Universe was a bit clumpy and asymmetric, suggesting that a "pure" Big Bang model does not quite describe the genesis and early evolution of the Universe. There is always something more to learn.

Weird Science

There are always some scientific projects that present somewhat unusual demonstrations of their basic mission. This year, we have seen the first text message ("O Canada") sent using sprays of vodka and a new chemical sensor; a notion not really sillier than last year's demonstration of a neutrino telegraph.

In other odd-science, an experiment at Trinity College Dublin to measure the viscosity of pitch has been running for the past 70 years. Eight drops of pitch have fallen from a standard viscosity testing funnel in that time, and this year the fall of the eighth drop was recorded on video. The viscosity of pitch? About 2 million times more viscous than honey.

Finally, there is nothing better to get the attention of a class of bored physics students than a good classroom demonstration. A standard is for the professor to back up against a wall, and let go of a heavy pendulum bob from just in front of his or her nose. When the bob makes its return trip to the immediate vicinity of that same nose, the professor's lack of flinching communicates the level of faith held by that individual in conservation of energy and momentum (with a bit of air drag added in.)

This classic demonstration has arguably been outdone by the demonstration of a supersonic ping-pong air cannon. Students used to a hand-operated pneumatic ping-pong gun are startled out of their slumber by the sonic boom and the impressive destructiveness of a 2.7 gram ping-pong ball flying at Mach 1.2. The video is worth a look.

So ends the year, and our brief look back at some of the significant achievements in science during 2013. The list is by no means exhaustive of course, and we'd love to hear your thoughts on the biggest discoveries of the year in the comments below.

Ed's note: We would like to take this opportunity to wish each and every one of our valued readers a happy, safe and scientific new year! The breakthroughs are sure to continue in earnest throughout 2014 and beyond, and Gizmag will endeavor to keep you up to date with the latest developments in science and technology.

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