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Suppliers can reap big benefits from China’s hi-tech boom

The boom in China’s hi-tech manufacturing has made the country a major market for vacuum technology. While challenges abound for foreign suppliers, the rewards can be great for those that can master the Chinese way of doing business.

China has the fourth largest economy in the world (in terms of gross domestic product) and has enjoyed an annual growth of about 9% throughout the past decade – more than double the global average. The country is home to a booming hi-tech sector, including a massive semiconductor industry, which is a big end user of vacuum technology.

The main opportunities for foreign suppliers are in the high-end vacuum market, which serves China’s semiconductor, metallurgical, solar-cell, medical, optical and other hi-tech industries. This high-end equipment is still largely made by US, European and Japanese firms, according to Kuno Herrmann, sales and marketing manager for Pfeiffer Vacuum. He estimates that this market is worth some €80 m per annum.

Although foreign companies have been selling in China for decades, the vacuum market took off about five or six years ago, says Frédéric della Faille, vice-president of sales at Alcatel Vacuum Technology. As a result, most leading vacuum suppliers have responded by opening sales offices and service centres there.

“Having a ‘presence’ is very, very important,” said Ting Zhang, founder and CEO of China Business Solutions Ltd, a UK-based business consultancy. A Chinese presence allows a firm to build trust by being closer to potential customers, and a local office can deliver more and better training and support to customers. “Before, there was very little need for this kind of upkeep,” said della Faille, because many vacuum users in China simply threw out their pumps after a few hundred hours and just bought new equipment.

Indeed, convincing buyers to invest in higher-quality vacuum equipment that will last has been a key challenge. Many Chinese customers look for the lowest bid, even though the higher initial costs of a well designed system are usually offset in the long run by a longer lifetime and significantly more efficient operation. “We have made this argument successfully in other parts of the world,” said Mark Fitch of Vergason Technology, but “it often falls on deaf ears in China”.

Understanding and adhering to industrial regulations in China can also be a major challenge for foreign vacuum suppliers. Local interpretations of the law can vary significantly throughout the country, so a firm must develop good working relationships with people in administrative positions. “The most popular buzz word for foreign business people in China is ‘guanxi’, which means ‘connections’,” says Zhang. Oerlikon Leybold Vacuum got guanxi by retaining a business consulting firm that had been working in China for some time. “You need to know someone there who understands the regulations and knows how to haggle,” explained Christina Steigler of Oerlikon Leybold.

Another way of dealing with the intricacies of the Chinese system is to hire locally. Although there is a large pool of skilled workers in China, Steigler’s experience is that few of them are able to speak English. Also, once a qualified Chinese employee has been identified, retaining their services can be difficult because employee turnover rates are often as high as 30%, according to Zhang.

After establishing a presence in China, the next step for a company is to start a manufacturing operation there. While this could be done through joint ventures with established Chinese businesses, many firms have legitimate concerns that their intellectual property will not be respected.

To minimize the risk of patent infringement, Oerlikon Leybold has been operating its own manufacturing site in China since 1997. According to Steigler, the facility has lower production costs than plants in the West and can avoid certain import fees. In addition, she believes that the “made in China” mark is a selling point with local companies, although it is less important for multinational customers.

Making it in China is not easy, and some vacuum companies have already failed. The lack of a suitable infrastructure for supporting foreign manufacturers is still a problem, according to Herrman. However, the overall situation for manufacturers is improving in China, says Zhang, with many regulations being updated, a growing awareness about intellectual property rights and a greater number of young people learning English.

Despite the problems, Herrmann believes that the high-end vacuum will enjoy an annual growth rate of at least 10% in the foreseeable future. He is confident that more foreign companies will start production in China. “It’s only a question of when,” he said.

Download a full digital version of the Vacuum Challenges and Solutions supplement here (PDF, 5MB).

Perfect lens could reverse Casimir force

The mysterious attraction between two neutral, conducting surfaces in a vacuum was first described in 1948 by Henrik Casimir and cannot be explained by classical physics. Instead it is a purely quantum effect involving the zero-point oscillations of the electromagnetic field surrounding the surfaces. These fluctuations exert a “radiation pressure” on the surfaces and the overall force is weaker in the gap between the surfaces than elsewhere, drawing the surfaces together. Tiny though it is, the Casimir effect becomes significant at distances of micrometres or less and actually causes parts in nano- and micro-electromechanical systems (NEMS and MEMS) to stick together.

Now, Leonhardt and Philbin have calculated that the Casimir force between two conducting plates can turn from being attractive to repulsive if a “perfect” lens is sandwiched between them. A perfect lens can focus an image with a resolution that is not restricted by the wavelength of light. Such a lens could be made from a metamaterial made of artificial structures that are engineered to have negative index of refraction — which means that the metamaterial bends light in the opposite direction to an ordinary material.

According to the researchers, the negative-index metamaterial is able to modify the zero-point oscillations in the gap between the surfaces, reversing the direction of the Casimir force. Indeed, the researchers believe that this repulsive force is strong enough to levitate an aluminium mirror that is 500nm thick, causing it to hover above a perfect lens placed over a conducting plate.

Since the Casimir force acts on the length scale of nanomachines, manipulating it could be important for future applications of nanotechnology. “In the nano-world, the Casimir force is the ultimate cause of friction,” Leonhardt told physicsworld.com. “Our result means we could now envision frictionless machines or novel micromotors.”

While physicists have had some success creating perfect lenses from negative-index metamaterials, the technology is still in its infancy. “The work points towards new applications of left-handed materials that are not strictly optical,” says Federico Capasso of Harvard University, who studies the effect of the Casimir force on MEMS. “However, the materials are not easy to make so the concept may take a few years to realise.”

Microscope unravels the intricacies of protein folding

Proteins – the building blocks of life – consist of a long chain of molecules called amino acids folded into a 3D shape. An atomic force microscope (AFM) can be used to study this folding by attaching one end of a protein to a substrate and the other end to the AFM’s cantilever. As the protein is stretched, the cantilever is oscillated and the force restoring the protein and cantilever back into equilibrium is measured.

In theory, monitoring this non-equilibrium force should provide information about the many intermediate equilibrium energy states that the protein goes through on its way to being fully extended. In practice, however, interpreting the data has proved controversial, and until now researchers have only had a clear understanding of the equilibrium states at the beginning and end of the folding process.

Now Ching-Hwa Kiang and colleagues from Rice University have improved the AFM technique to determine the intermediate states. To do this, they built a computer program based on an equation formulated by University of Maryland physicist Chris Jarzynski a decade ago.

Although scientists had believed “Jarzynski’s equality” could be used to obtain equilibrium information from non-equilibrium measurements, none had been able to apply it successfully. “Through numerous discussions with Jarzynski, we had a thorough understanding of where and how the theory applies,” Kiang explained.

The Rice group proved their technique works using section of “titin”, the largest known protein and the one that constitutes elastic muscle in the heart, and managed to map eight individual energy states as they used an AFM to unfold it. This, they say, paves the way for investigating how environmental changes such as temperature affect protein folding.

Atoms swap spins

Optical lattices use criss-crossing laser beams to create a matrix of potential wells that can each trap one or more atoms. They are one of several experimental systems that could be used to create practical quantum computers, which exploit the ability of quantum systems to exist in two states at the same time. Rather than use bits, which are either 1 or 0, quantum computers use qubits, which can be in a superposition of both 1 and 0 simultaneously. The idea is that if a quantum computer has N such qubits, these can then be combined or “entangled” to represent 2^N values at the same time. By processing each of these values simultaneously, a quantum computer could, in principle, operate exponentially faster than its classical counterpart.

A SWAP gate exchanges the state of two qubits — the spin state of two atoms in an optical lattice, for example. If one atom starts in spin state 1 and the other in 0 (1-0), they end up in 0 and 1 respectively (0-1). What is more interesting to those trying to build quantum computers is the half-SWAP gate, whereby the process is stopped halfway when the state of each individual atom is simultaneously 1 and 0 — and the atoms are entangled. Then, the two atoms could, in principle be physically separated while still entangled.

Now Trey Porto and colleagues at NIST and the University of Maryland in the US, have created at SWAP gate in an optical lattice. They began with two overlapping lattices that were offset slightly in space from one another. In both lattices, each well was occupied by one atom and a radio signal was used to set the spins of all the atoms in one lattice to 1 and all the atoms in the other lattice to 0.

The researchers then carefully adjusted the laser beams to merge the two lattices into one lattice in which two atoms occupy one well. When the two atoms are in the same well, quantum mechanics dictates that the overall quantum state of the two atoms must have a specific symmetry and this restriction causes the system to oscillate between two spin states: 0-1 and 1-0.

By switching off the trapping lasers and applying a magnetic field gradient to the ensemble, the researchers were able to measure the spin state of the atoms at different points in time and confirm that they were oscillating between the two spin states with a period of about 0.4 ms

The team also performed the experiment with both atoms in the same initial states (0-0 and 1-1) and saw no oscillations. Porto told physicsworld.com that this was particularly challenging to achieve because these states are more likely to be destroyed by noise than 0-1 and 1-0.

This is not the first time that a SWAP gate has been demonstrated – in 2005 physicists at Harvard University swapped spin states between electrons confined to two quantum dots. However, the Harvard experiment could only swap 0-1 and 1-0 states, and not 0-0 and 1-1. Although the latter two swaps seem trivial, any practical gate must be able to handle these states.

Porto accepts that the NIST team have also fallen short of performing a complete half swap, because they did not separate the atoms in the entangled state, something that the team are now working on.

Another key challenge facing Porto and others who are trying to build quantum computers based on optical lattices is how to read and write information from individual atoms and manipulate individual wells. This was not done in this experiment — instead the measurements were made on the entire ensemble of atoms and all the wells were controlled in unison.

Graphene oxide weaved into ‘paper’

First isolated in 2004, graphene is a one-atom-thick sheet of graphite that, aside from having unique electronic properties, is very strong. But as of yet there is no way of producing it in large quantities, which has limited its potential as a building block for new types of specialist materials.

Now, however, a group from Northwestern University in the US including Rodney Ruoff have discovered that large quantities of oxidized graphene can be weaved together to create a new type of “paper” that is stiffer and stronger than other thin materials.

“My dream has been to disassemble graphite into individual sheets, and then reassemble those sheets in different ways,” Ruoff told physicsworld.com. To do this his group begins by oxidizing graphite to make graphite oxide, which leaves roughly half the carbon atoms with an attached oxygen atom. When graphite oxide is mixed into water, these oxygen atoms repel water molecules, forcing the individual layers – graphene oxide – to disperse or “exfoliate”. The researchers filter this exfoliated mixture through a membrane, which collects the layers in such an arrangement to produce graphene oxide paper.

Normal graphite has a delicate structure, needing only a small lateral force to break apart its regularly-stacked layers. Conversely, the layers in graphene oxide paper interweave with one another and wrinkle on larger scales. This allows load to be distributed across the structure, making it stronger than graphite foil and “bucky paper”, which is made from carbon nanotubes. In fact, Ruoff claims, the only material stronger could be diamond.

Many layers

The interwoven structure also lets individual layers shift over each other, so that the collective layers become pliable. But most importantly the paper can be chemically tuned by altering the amount of oxygen on the layers. Reducing the oxygen content, for example, would take it from being an electrical insulator to a good conductor. Moreover, the paper could be infused with polymers, ceramics or metals, to make composite materials that outperform their pure counterparts.

This wide array of properties could mean applications as diverse as membranes with controlled permeability to supercapacitors for energy storage.

Artificial swimmers have no moving parts

Making micrometre-sized objects swim is no easy task because over very short distances, water behaves like a very viscous fluid such as honey. Some bacteria manage to swim by using highly specialized undulating whips called flagella – and while some progress has been made in creating artificial flagella, they have proved very difficult to mimic in a tiny machine.

In 2005 Ramin Golestanian, a theoretical physicist at the University of Sheffield in the UK and colleagues proposed a much simpler way of propelling tiny objects that uses no moving parts. Now a team led by fellow Sheffield physicist Richard Jones has created such a propulsion system for making particles swim in a solution of water and hydrogen peroxide.

The team used polystyrene balls that were about 1.6µm in diameter and had one side coated with platinum — a catalyst that boosts the rate at which hydrogen peroxide is converted into oxygen and water. This reaction decreases the concentration of hydrogen peroxide in the region near the platinum-coated side of the sphere, causing water to flow away from the region in order to maintain equilibrium. This flowing water pushes the object in a specific direction relative to the coating– if the platinum is on the right hand side of the sphere, for example, the sphere would move to the left.

By looking at the system with an optical microscope, the researchers saw that the balls could reach speeds of 5µm/s — which is not far off the 10µm/s observed in similarly-sized bacteria. According to Golestanian, the propulsion technique could be adapted to work in other liquids including blood, which could someday allow micromachines to swim within the body to deliver drugs to specific locations.

However like bacteria, the swimmers also have to contend with another consequence of being very small –- being knocked off course by random collisions with water molecules in a process called Brownian motion. Indeed, after a few seconds of motion in a specific direction, the Sheffield swimmers followed completely random paths.

Golestanian told physicsworld.com that thermodynamics makes it impossible to design a tiny object that would be able to avoid Brownian motion on its own and travel in a straight line. Instead, he believes that the objects could be guided externally – for example, if a magnetic dipole could be placed in the object, it could be steered using a magnetic field.

Tiny magnets help drugs reach the spot

Many pulmonary diseases, such as asthma, cystic fibrosis and lung cancer, need drugs to be inhaled so that they can reach the affected area. To do this, patients have to gasp on an inhaler that emits the particulate drugs into the windpipe.

But the effectiveness of these inhalers is not great: typically only 4% of the drug makes it through the windpipe, forcing doctors to administer higher doses, which can exacerbate unwanted side effects.

A better way, according to Carsten Rudolph at Ludwig-Maximilians University in Munich and co-workers from elsewhere in Germany, is to mix the drugs with iron-oxide magnetic nanoparticles and microdroplets of water, or so-called “nanomagnetosols”. These nanomagnetosols can then be guided directly to problem areas using a magnetic field. The idea is not new, but Rudolph’s group show for the first time that it can be performed in a real organism – in this case, a mouse.

The researchers began by creating a computer simulation of a mouse’s airways where the windpipe forks into two bronchi, taking into account air flow rates measured in previous physiological studies. Assuming they were to use nanomagnetosol droplets with an average diameter of 3.5 µm, they predicted that they could use a magnetic probe placed close to a bronchus to get up to 16% coverage of the microdroplets.

Rudolph’s group tested their prediction by opening up the chest of a mouse, and placed a specially designed magnetic tip probe with a high flux gradient of 100 Tm^-1 next to one of the lungs. When they squirted the nanomagnetosol droplets into the mouse’s airways, they found that the lung next to the probe received eight times more drug coverage than the one without. Upon placing the probe on another mouse with its chest intact, the benefit was reduced, with just two and a half times more coverage.

Performing the same feat in humans will not be so straightforward, however. Human lungs are much larger and more intricate, so it will be difficult to guide the nanomagnetosol droplets with the same accuracy. Moreover, a much more powerful magnetic probe will be required to overcome the additional distance between the probe and inner lung.

Supersolid saga continues

The first convincing evidence for supersolidity came in 2004, when US physicists Moses Chan and Eun-Song Kim were monitoring the rotation of a sample of helium-4 supported inside a torsion oscillator. As they reduced the temperature below 230 mK, they noticed that the oscillations sped up slightly, and concluded that 1% of the sample had become a supersolid and was therefore staying still in the lab frame.

At first, this was thought to be proof of a phase transition predicted in the late 1960s, which suggested that close to absolute zero any lattice vacancies present in a sample would collapse into the same quantum state, becoming a so-called Bose-Einstein condensate. In this supersolid phase, the vacancies would be able to move throughout the rest of the solid effortlessly like a superfluid.

More recent calculations, however, have shown that there would not be enough vacancy condensation at low temperature to give supersolid signal as large as 1%.

One alternative explanation is that the signal actually comes from supersolidity involving tiny “grain boundaries”, but this was ruled-out experimentally last month by Chan, who told Physics Web that he suspected the signal could be originating in dislocations within the crystal lattice.

Now, Massimo Boninsegni from the University of Alberta and collaborators from the US and Switzerland have backed-up this suspicion by simulating a “screw” dislocation in a microscopic helium-4 crystal. Screw dislocations form when a break in the crystal lattice causes atoms to stack-up in a structure akin to a spiral staircase, and for complex helium-4 crystals have been too difficult to simulate accurately in the past.

Using a new computer algorithm Boninsegni’s group found that, as they reduced the temperature parameter towards absolute zero, the core of the screw dislocation acted like a tube through which some of the atoms could flow freely – essentially in one dimension – as a superfluid. “This is an important aspect experimentally, as a one-dimensional system has distinct physical signatures that can be probed by measurement,” Boninsegni said.

The researchers say that a network of these superfluid cores could produce a supersolid signal in a real sample, although it would not produce one as high as the 1% originally recorded by Kim and Chan. This signal strength, they suggest, might be due to auxiliary sources, such as “pockets” of superfluid.

Partnership to boost fuel-cell research

Fuel cells are typically made up of an anode and a cathode, separated by a membrane that conducts protons but not electrons. When a fuel, such as hydrogen, is supplied to the anode, it is broken into its constituent protons and electrons. The protons are attracted to the cathode, while the electrons – unable to travel through the membrane – are harnessed in an adjacent circuit to produce electrical energy.

Fuel-cell technologies could bring important environmental benefits because they are much cleaner than traditional sources of power such as internal combustion engines. At worst, fuel cells release small amounts of carbon dioxide, but often the only by-product is water.

In this agreement, physicists at Oak Ridge National Laboratory (ORNL), which is owned by the US Department of Energy, will use their skills in the imaging of solids and surfaces to develop metal and carbon bipolar plates for the anodes and cathodes. Jülich researchers will share their materials and fabrication techniques.

The researchers will concentrate on two types of fuel cells: proton-exchange membrane fuel cells (PEMFCs) and direct-methanol fuel cells (DMFCs), both of which are already used to some extent commercially. Because of their relatively high output, PEMFCs are primarily being developed for the automotive industry. DMFCs can currently only produce small amounts of power, albeit over a long period of time, which makes them better suited to portable devices such as mobile phones, digital cameras or laptops.

“This agreement underscores the Department of Energy’s commitment to the [US] president’s hydrogen fuel initiative,” said Tim Armstrong, the manager of ORNL’s fuel cells program.

Liquid jets bounce along

The photographs were taken by Matthew Thrasher and colleagues at the University of Texas at Austin, who built a rotating oil bath into which a stream of oil was dropped under the watchful eye of a video camera. The photographs reveal that when the stream strikes the surface of the bath, it slides along the surface on a thin layer of air. Furthermore, the force of impact creates a bowl-shaped indentation in the surface of the liquid that acts as a ramp, launching the stream back into the air (see figure “Bouncing jet”). The stream then arcs over the surface and plunges back into the liquid, sometimes emerging in a second arc.

Skimming

Bouncing was observed in a number of different silicone oils with viscosities ranging from 56 to 560 times that of water. The arc became smaller when the bath was rotated more quickly until the jet no longer lifted off the surface, but rather skimmed its surface (see figure “Skimming”)

Thrasher told Physics Web that a crucial requirement for bouncing is that the layer of air supporting the jet must not break into air bubbles, which would disrupt the stream. He adds that an understanding of why some liquids bounce while others bubble could help improve the metal casting process — in which molten material is poured into a mould and bubbles must be carefully avoided because they weaken the solid metal. Conversely, plunging jets are often used to introduce air bubbles into liquids – a familiar example being bath bubbles that form under a running tap. Therefore Thrasher believes that those designing liquid aeration systems should understand how to avoid the bouncing of fluids.

Thrasher came up with the idea for the experiment when he was pouring oil from one container to another and noticed that the stream of poured oil would sometimes bounce across the surface of the container. In their paper, the researchers suggest several simple experiments for observing bouncing jets in the classroom or even at home.

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