What is matter? What is energy? What holds matter together? How do the various constituents of the universe interact at the most basic level? Where does the Earth sit in relation to the rest of the uni- verse? Can we predict the movements of the stars?
Physics gives us the knowledge to address remarka- ble questions like these. But knowledge is also pow- er: a better understanding of these laws, allows us to improve the ways we interact with, and harness our environment. And if you look at the rapid develop- ment in human technology over the past two centu- ries, it is amazing just how much technological change has been derived from advances in physics.
Perhaps the most clear-cut example in this respect is the dramatic transformation that electricity has brought about in all modern societies. Our whole way of living now is completely dependent upon being able to generate, transmit, and harness electric power in a safe and efficient manner – all of which is ultimately underpinned by our understanding of physics.
Keeping up with the ever growing demand for gen- erating electricity with minimal environmental im- pact will be a significant challenge in the years to come.
No matter how much we know there is always more
Physics: A fundamental force for future security
Researchers at the Helmholtz Center Berlin (HZB) have achieved a deeper understanding of an undesired effect in thin film solar cells based on amorphous silicon—one that has puzzled the scientific community for the last 40 years. The researchers were able to demonstrate that tiny voids within the silicon network are partly responsible for reducing solar cell efficiency by some 10 to 15% as soon as you start using them. Their work has now been
published in Physical Review Letters.
Amorphous silicon thin film solar cells are considered a promising alternative to solar cells based on highly purified silicon wafers, which have been dominating photovoltaic power generation. A major advantage of amorphous silicon thin film photovoltaics, where a glass substrate is coated with a light active material less than a thou-
sandth of a millimeter thick, is that the cell fabrication is considerably simpler and much less costly than in the case of conventional crystal- line silicon solar cells. On the other hand, a potential disad- vantage is the low conversion efficiency from solar energy to electricity. Because of the disordered nature of amor- phous silicon, solar cells are subject to the Staebler- Wronski effect ..Read more...
Possible explanation for light-degradation silicon solar cells
Department of Physics—United Arab Emirates University
Feb. 15, 2014 Volume 4, Issue 7In the initial state (left), the voids' internal surfaces are saturated with hydrogen atoms so that no defects are ob- served. Light-induced charge carriers (h+) destabilize atomic bonds. The breaking of atomic bonds causes defects (indicated by the vertical arrows on the right hand side), which translates to reduced solar cell efficiency.
to discover – and from every discovery we generate great new and practical technologies.
Knock-on effects
Whether physicists studying fundamental principles, such as quantum mechanics, are more likely to in- vent new devices by applying these principles seren- dipitously, or by design, doesn't matter as both ap- proaches work.
What is remarkable is the extent to which fundamen- tal breakthroughs can lead to diverse technological consequences.
Take, for example, the transistor and diode, which are used in electronic watches, calculators, pacemak- ers, hearing aids, cellular phones, global positioning systems (GPSs), radios, computers ...Read more...
Electricity – just one bright idea to stem from physics. Credit: Flick- r/JonathanCohen
Weekly news from around the world compiled by Dr. Ilias Fernini
Astronomy and Physics News
Physics: A fundamental force for
future security 1
Possible explanation for light- degradation silicon solar cells 1 China's Jade Rabbit rover comes 'back to life': Xinhua 2 Superconductivity in orbit: Scien- tists find new path to loss-free electricity
2
Scientists investigate tiny protein crystals with synchrotron radiation 2
Researchers develop first single-
molecule LED 3
Graphene's love affair with water 3
ANU astronomers discover oldest
star 3
IC 1805: Light from the Heart 4 Flowing Water on Mars Appears Likely But Hard to Prove 4 Inside this issue:
China's troubled Jade Rabbit lunar rover has survived a bitterly cold 14-day lunar night, officials said Thursday, prompting hopes it can be repaired after suffering a malfunction last month.
The problem was a setback for Beijing's ambitious military-run space program, which includes plans for a permanent orbiting station by 2020 and eventually sending a human to the moon.
"The rover stands a chance of being saved as it is still alive," Pei Zhaoyu, spokesman for China's lunar probe pro- gram told the official news agency Xinhua.
An earlier report by the semi-official Chi- na News Service said an attempt to re- store the vehicle to full functionality on Monday had been unsuccessful.
The rover, named Yutu or Jade Rabbit after the pet of Chang'e, the goddess of the moon in Chinese mythology, experi- enced a "mechanical control abnormality"
as the lunar night fell on January 25, pro- voking an outpouring of sympathy from Chinese Internet users.
But Pei said: "Yutu has come back to life!", adding that the rover "went into sleep under an abnormal status".
Scientists had been ...Read more...
world's most powerful X-ray laser in Stanford (US). "Since only a few of these valuable crystals are need- ed, this method opens up new possibilities for the structural anal- ysis of biomolecules," said CFEL scientist Cornelius Gati, lead au- thor of a research study which describes this new method in IU- CrJ, the high-profile scientific journal of the International Union of Crystallography.
From the structure of a biomole- cule at the atomic-level, biologists At DESY, scientists from the Center
for Free-Electron Laser Science (CFEL), the European Molecular Biology Laboratory (EMBL) and the universities of Hamburg and Lübeck created new analysis possibilities for delicate biomolecules. At the X-ray source PETRA III, the scientists X- rayed micrometre-sized crystals of a key enzyme involved in sleeping sickness, thereby determining its atomic structure. The obtained struc- tural data correspond to earlier anal- yses of the same enzyme at the
can determine its functioning and properties, thus for example allowing the design of tailor-made medication.
For decoding the highly complex molecules, scientists use X-ray crys- tallography. By placing a biomolecu- lar crystal in an X-ray beam, they can measure the pattern of X-ray light that encodes the three-dimensional structure of the constituent mole- cules of the crystal. The molecular structure is decoded using sophisti- cated computational methods. "The principle can be explained as a kind of mathematical ...Read more...
China's Jade Rabbit rover comes 'back to life': Xinhua
P a g e 2 V o lu m e 4 , I s s u e 7
Scientists investigate tiny protein crystals with synchrotron radiation Superconductivity in orbit: Scientists find new path to loss-free electricity
Armed with just the right atomic arrange- ments, superconductors allow electricity to flow without loss and radically enhance ener- gy generation, delivery, and storage. Scientists tweak these superconductor recipes by swap- ping out elements or manipulating the va- lence electrons in an atom's outermost orbital shell to strike the perfect conductive balance.
Most high-temperature superconductors contain atoms with only one orbital impact- ing performance—but what about mixing those elements with more complex configura- tions?
Now, researchers at the U.S. Department of Energy's Brookhaven National Laboratory have combined atoms with multiple orbitals
A nylon loop containing a thin film loaded with microcrystals. The X-ray beam scans the loop.
and precisely pinned down their electron distributions. Using advanced electron dif- fraction techniques, the scientists discovered that orbital fluctuations in iron-based com- pounds induce strongly coupled polarizations that can enhance electron pairing—the essen- tial mechanism behind superconductivity.
The study, set to publish soon in the jour- nal Physical Review Letters, provides a breakthrough method for exploring and improving superconductivity in a wide range of new materials.
"For the first time, we obtained direct exper- imental evidence of the subtle changes in electron orbitals by ...Read more...
These images show the distribution of the valence electrons in the samples explored by the Brookhaven Lab collaboration -- both feature a central iron layer sandwiched between arsenic atoms. The tiny red clouds (more electrons) in the undoped sample on the left (BaFe2As2) reveal the weak charge quadrupole of the iron atom, while the blue clouds (fewer electrons) around the outer arsenic ions show weak polarization. The superconducting sample on the right (doped with cobalt atoms), however, exhibits a strong quadrupole in the center and the pronounced polarization of the arsenic atoms, as evidenced by the large, red balloons. Credit: Brookhaven Na- tional Lab
Researchers develop first single-molecule LED
The ultimate challenge in the race to miniaturize light emitting diodes (LED) has now been met: A team led by the Institut de Physique et de Chimie des Matériaux de Stras- bourg (IPCMS, CNRS/Université de Strasbourg), in collaboration with UPMC and CEA,
has developed the first ever single- molecule LED. The device is formed from a sin-
gle polythiophene wire placed between the tip of a scanning tunneling microscope and a gold surface. It emits light only when the current passes in a cer- tain direction. This experimental tour de force sheds light on the interactions between electrons and
photons at the smallest scales.
Moreover, it represents yet anoth- er step towards creat-
ing components for a molecular computer in the future. This work has recently been published in the journal Physical Review Letters.
Light emitting diodes are compo- nents that emit light when an elec- tric current passes through them and only let light through in one direction. LEDs play an important role in everyday life, as light indi- cators. They also have a promising future in the field of lighting, where they are progressively taking over the market. A major ad- vantage of LEDs is that it is possi-
ble to make them very small, so point light sources can be ob- tained. With this in mind, one final miniaturization hurdle has recently been overcome by researchers at IPCMS in Strasbourg, in collabo- ration with a team from the Insti- tut Parisien de Chimie Moléculaire (CNRS/UPMC): they have pro- duced the first ever single- molecule LED.
To achieve this, they used a single polythiophene wire. This sub- stance is a good electricity conduc- tor. It is made of hydrogen, car- bon and sulfur, and is used to make larger LEDs .Read more….
tion technologies.
One-atom-wide graphene capillaries can now be made easily and cheaply by piling layers of graphene oxide – a derivative of graphene – on top of each other. The resulting multilayer stacks (laminates) have a structure similar to nacre (mother of pearl), which makes them also mechanically strong.
Two years ago, University of Manchester re- searchers discovered that thin membranes made from such laminates were impermeable to all gases and vapours, except for water. This means that even helium, the hardest ...Read more...
Graphene has proven itself as a wonder material with a vast range of unique proper- ties. Among the least-known marvels of graphene is its strange love affair with water.
Graphene is hydrophobic – it repels water – but narrow capillaries made from graphene vigorously suck in water allowing its rapid permeation, if the water layer is only one atom thick – that is, as thin as graphene itself.
This bizarre property has attracted intense academic and industrial interest with intent to develop new water filtration and desalina-
ANU Research School of Astron- omy and Astrophysics.
"This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars."
The star was discovered using the ANU SkyMapper telescope at the Siding Spring Observatory, which is searching for ancient stars as it conducts a five-year project to produce the first digital map the southern sky.
The ancient star is around 6,000 A team led by astronomers at The
Australian National University has discovered the oldest known star in the Universe, which formed shortly after the Big Bang 13.7 billion years ago. The discovery has allowed astronomers for the first time to study the chemistry of the first stars, giving scientists a clearer idea of what the Universe was like in its infancy.
"This is the first time that we've been able to unambiguously say that we've found the chemical fingerprint of a first star," said lead researcher, Dr Stefan Keller of the
light years from Earth, which Dr Keller says is relatively close in astronomical terms. It is one of the 60 million stars photographed by SkyMapper in its first year.
"The stars we are finding number one in a million," says team mem- ber Professor Mike Bessell, who worked with Keller on the research.
"Finding such needles in a haystack is possible thanks to the ANU SkyMapper telescope that is unique in its ability to find stars with low iron from their colour." ...Read more….
P a g e 3 V o lu m e 4 , I s s u e 7
Graphene's love affair with water
Credit: University of Manchester
ANU astronomers discover oldest star
Artist impression of electroluminescence in a single polythiophene molecular wire suspend- ed between the tip and the surface of a scan- ning tunneling microscope. Image: Guillaume Schull – IPCMS, CNRS/Université de Strasbourg
Lead researcher Dr Stefan Keller and team member Professor Mike Bessell. Image courtesy David Paterson, ANU.
College of Science - United Arab Emirates University POB 15551
Al-Ain
United Arab Emirates
http://fos.uaeu.ac.ae/department/physics
"We still don't have a smoking gun for exist- ence of water in RSL, although we're not sure how this process would take place without water," said Ojha. "Just like the RSL them- selves, the strength of the spectral signatures varies according to the seasons. The signatures are stronger when it's warmer and less signifi- cant when it's colder."
The research team also notes that the lack of water-related absorptions rules out hydrated salts as a spectrally dominant phase on RSL slopes. For example, ferric sulfates have been found elsewhere on Mars and are a potent anti- freeze. If such salts are present in RSL, then they must be dehydrated considerably under exposure to the planet's conditions by the time CRISM observes them in the mid-afternoon.
The findings were recently published in Geo- physical Research Letters, and the Georgia Tech duo's newest paper, published in the journal Icarus, indicates that predicting where RSL will appear is, at best, a guessing game.
Ojha, Wray, and several Arizona-based col- leagues looked at every image gathered by the High Resolution Imaging Science Experiment (HiRISE) from March to October of 2011.
Martian experts have known since 2011 that mysterious, possibly water-related streaks appear and disappear on the planet's surface. Georgia Institute of Technology Ph.D. candidate Lujendra Ojha discovered them while an undergraduate at the Univer- sity of Arizona.
These features were given the descriptive name of recurring slope lineae (RSL) be- cause of their shape, annual reappearance and occurrence generally on steep slopes such as crater walls. Ojha has been taking a closer look at this phenomenon, searching for minerals that RSL might leave in their wake, to try to understand the nature of these features: water-related or not?
Ojha and Georgia Tech Assistant Professor James Wray looked at 13 confirmed RSL sites using Compact Reconnaissance Imag- ing Spectrometer for Mars (CRISM) images.
They didn't find any spectral signature tied to water or salts. But they did find distinct and consistent spectral signatures of ferric and ferrous minerals at most of the sites.
The minerals were more abundant or fea- tured distinct grain sizes in RSL-related materials as compared to non-RSL slopes.
They hunted for areas that were ideal locations for RSL formation: areas near the southern mid- latitudes on rocky cliffs. They found 200, but barely any of them had RSL.
"Only 13 of the 200 locations had confirmed RSL," said Ojha. "There were significant differ- ences in abundance and size between sites, indi- cating that additional unknown factors such as availability of water or salts may play a crucial role in RSL formation." ...Read more...
Flowing Water on Mars Appears Likely But Hard to Prove
Phone: 00-971-3-7136336 Fax: 00-971-3-767-1291 E-mail: [email protected]
Physics Department
IC 1805: Light from the Heart
Image Credit & Copyright: César Blanco González
Explanation: Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds about 7,500 light-years away in the Per- seus spiral arm of our galaxy. Stars were born in this region whose nickname, the Heart Nebula, derives from its Valentine's-Day-appropriate shape. The clouds themselves are shaped by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster Melotte 15about 1.5 million years young. This deep telescopic image maps the pervasive light of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble images of star forming regions. The field of view spans about two degrees on the sky or four times the diameter of a full moon. The cosmic heart is found in the constellation of Cassiopeia, the boastful mythical Queen of Aethiopia .
Dark elongated streaks called Recurring Slope Lineae observed in HiRISE images of Mars.
The RSL form on sun facing slopes during warm season and fade during cold season.
