As yet another biofuels company prepares for a stock offering, some wonder if the company is worthy of going public at all.

In 2004, a startup called Nanosys tried to go public. It had recruited some of the world's top nanoscientists for its board and had bought up hundreds of nanotech patents. The idea was that it could revolutionize TV displays, batteries, and maybe even golf balls. It had no product, but so what? Nanotech seemed like it could change everything.

That is when a venture capitalist named Vinod Khosla, then with Kleiner, Perkins, Caufield & Byers, cried fraud. A speech of Khosla's at Stanford University helped to not only torpedo the Nanosys IPO but also burst a short-lived nanotech bubble.

New energy-storage technology could surpass today's batteries in capacity and durability.

A startup called Nanotune says its ultracapacitor technology could make electric cars cheaper and extend their range. The company, based in Mountain View, California, has developed a way to make electrodes that results in ultracapacitors with five to seven times as much storage capacity as conventional ones.

Conventional ultracapacitors, which have the advantage of delivering fast bursts of power and can be recharged hundreds of thousands of times without losing much capacity, are too expensive and store too little energy to replace batteries.

Battery draws power from salinity difference between freshwater and saltwater.

The difference in salinity between freshwater and saltwater holds promise as a large source of renewable energy. Energy is required to desalinate water, and running the process in reverse can generate energy. Now a novel approach based on a conventional battery design that uses nanomaterials could provide a way to harvest that energy economically. 

The new device, developed by researchers at Stanford University, consists of an electrode that attracts positive sodium ions and one that attracts negative chlorine ions.

A startup says technology inspired by RAID hard drives can boost power output by up to 50 percent.

A startup called TenKsolar, based in Minneapolis, says it can increase the amount of solar power generated on rooftops by 25 to 50 percent, and also reduce the overall cost of solar power by changing the way solar cells are wired together and adding inexpensive reflectors to gather more light.

TenKsolar says its systems can produce power for as little as eight cents a kilowatt-hour in sunny locations. That's significantly more expensive than electricity from typical coal or natural-gas power plants, but it is less than the average price of electricity in the United States. 

Delivering light-sensitive proteins to the retinas of blind mice restores some vision.

Viruses can deliver light-sensitive proteins to specific cells in the retinas of blind mice, allowing rudimentary vision, according to new research. Although previous studies have shown that the light-sensitive proteins can be beneficial, the delivery methods were not practical for humans. The viral-delivery method is similar to ones already used in human gene therapy.

The new light-sensitive proteins were active for the length of the study, about 10 months, suggesting the treatment would work long-term. In addition, the therapy appeared safe; the proteins, which were derived from algae, remained within the eye, and they did not trigger inflammation.

A startup is developing a simple ultrasound method to get cancer drugs into the brain.

The cells lining the brain's blood vessels are tightly packed together—like a good defensive line, they keep bacteria and other blood-borne intruders from getting through, shielding the brain. But this protective layer, called the blood-brain barrier, also thwarts efforts to deliver drugs like chemotherapy agents to the brain, so scientists have long searched for ways to disrupt it selectively to allow treatments in. A startup company called Perfusion Technology is developing a technique to open this barrier by bathing the brain in ultrasound waves.

A nonprofit creates a new heart monitoring machine employing wireless technology.

An inexpensive portable device could make it easy to monitor fetal health in remote locations, and it might also provide an alternative to more expensive machines currently used in doctors' offices in the developed world.

The device, a cardiotocography machine dubbed Sense4Baby, was designed by engineers at the nonprofit West Wireless Health Institute, a medical research organization whose mission is to use wireless technology to reduce the cost of health care.

Designing new genomes could speed the creation of vaccines and biofuel-producing bacteria

The bacteria growing on stacks of petri dishes in Daniel Gibson's lab are the first living creatures with a completely artificial genome. The microbes' entire collection of genes was edited on a computer and assembled by machines that create genetic fragments from chemicals and by helper cells that pieced those fragments together. Gibson hopes that being able to design and create entire genomes, instead of just short lengths of DNA, will dramatically speed up the process of engineering microbes that can carry out tasks such as efficiently producing biofuels or vaccines.

The automaker aims to bring a cheap hybrid technology used in some large vehicles to passenger cars.

The U.S. Environmental Protection Agency and Chrysler Group have partnered to test a hydraulic hybrid system for minivans that could be cheaper than conventional hybrid systems and could save more gasoline. EPA and Chrysler are each spending $2 million (for a total of $4 million) on the project, and they expect to begin road testing next year.

Conventional hybrids save gas in part by using energy from braking to charge a battery. A hydraulic hybrid captures energy by using a hydraulic pump instead of conventional friction brakes to slow the vehicle. The pump forces fluid into a tank, compressing air that can then be used to help propel the vehicle.

A startup has developed a device that uses magnetic particles to identify pathogens rapidly.

A startup called T2 Biosystems is developing a test that uses magnetic nanoparticles to detect blood-borne infections in hours—compared to the days it now takes using conventional lab methods. The company's first device—about the size of a printer—will target Candida, a fungus that is the third-most-common cause of hospital-acquired infections. The detection system can identify Candida in human blood samples in about two hours. Clinical trials involving samples from actual patients are in the works.