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汤圆儿圆 @ 30th. 09. 2013 11,544 views
两位英国艺术家Andy Moss and Jamie Wardley为了庆祝9月21世界和平日，以及纪念那些在第二次世界大战诺曼底登陆战中牺牲的士兵们，想到了这样独特的方法。简单的模版制造，志愿者的加入，没有过多的花费，却也让人心暖，好创意！共有9千名士兵，随着海水的洗礼，愿逝者安息，世界和平。1designperday
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JILA Physicists Discover 'Quantum Droplet' in Semiconductor
From NIST Tech Beat: February 26, 2014
JILA physicists used an ultrafast laser and help from German theorists to discover a new semiconductor quasiparticle—a handful of smaller particles that briefly condense into a liquid-like droplet.
Quasiparticles are composites of smaller particles that can be created inside solid materials and act together in a predictable way. A simple example is the exciton, a pairing, due to electrostatic forces, of an electron and a so-called "hole," a place in the material's energy structure where an electron could be, but isn't.
The new quasiparticle, described in the Feb. 27, 2014, issue of Nature* and featured on the journal's cover, is a microscopic complex of electrons and holes in a new, unpaired arrangement. The researchers call this a "quantum droplet" because it has quantum characteristics such as well-ordered energy levels, but also has some of the characteristics of a liquid. It can have ripples, for example. It differs from a familiar liquid like water because the quantum droplet has a finite size, beyond which the association between electrons and holes disappears.
Although its lifetime is only a fleeting 25 picoseconds (trillionths of a second), the quantum droplet is stable enough for research on how light interacts with specialized forms of matter.
"Electron-hole droplets are known in semiconductors, but they usually contain thousands to millions of electrons and holes," says JILA physicist Steven Cundiff, who studies the properties of cutting-edge lasers and what they reveal about matter. "Here we are talking about droplets with around five electrons and five holes.
"Regarding practical benefits, nobody is going to build a quantum droplet widget. But this does have indirect benefits in terms of improving our understanding of how electrons interact in various situations, including in optoelectronic devices."
The JILA team created the new quasiparticle by exciting a gallium-arsenide semiconductor with an ultrafast red laser emitting about 100 million pulses per second. The pulses initially form excitons, which are known to travel around in semiconductors. As laser pulse intensity increases, more electron-hole pairs are created, with quantum droplets developing when the exciton density reaches a certain level. At that point, the pairing disappears and a few electrons take up positions relative to a given hole. The negatively charged electrons and positively charged holes create a neutral droplet. The droplets are like bubbles held together briefly by pressure from the surrounding plasma.
JILA's experimental data on energy levels of individual droplet rings agreed with theoretical calculations by co-authors at the University of Marburg in Germany. JILA researchers found they could tap into each energy level by tailoring the quantum properties of the laser pulses to match the particle correlations within the droplets. The droplets seem stable enough for future systematic studies on interactions between light and highly correlated states of matter. In addition, quasiparticles, in general, can have exotic properties not found in their constituent parts, and thus, can play a role in controlling the behavior of larger systems and devices.
JILA is a joint institute of the National Institute of Standards and Technology (NIST) and University of Colorado Boulder. Cundiff is a NIST physicist. The JILA research is supported by the National Science Foundation, NIST and the Alexander von Humboldt Foundation.
*A.E. Almand-Hunter, H. Li, S.T. Cundiff, M. Mootz, M. Kira and S.W. Koch. Quantum droplets of electrons and holes. Nature. Feb. 27, 2014.
Eggshells could find use in ceramics production
Don't throw those eggshells away – they could be made into ceramics (Photo: Shutterstock)
According to the US Department of Agriculture, every year approximately 455,000 tons (412,769 tonnes) of discarded eggshells must be transported and disposed of in the US alone. Now, however, scientists at the University of Aveiro in Portugal have developed a method of using such eggshell waste in the production of ceramic goods.
Although the specifics of the technology are still under wraps, it involves incorporating crushed eggshells into a ceramic slurry which is subsequently processed "according to a specific protocol that includes a 3-cycle cooking phase." Samples of porous pavement made from the slurry exhibit desirable qualities such as porosity and water absorption, and are overall considered to be of sufficient quality to meet industry standards.
Besides keeping eggshells out of landfills, the process could also allow ceramics manufacturers to save money – the calcium in the shells would be a lower-cost alternative to calcite, which is traditionally used in the production of ceramic items. Additionally, calcite must be mined, with all the environmental consequences that doing so entails.
What's more, businesses in the food industry supplying the shells could make money by selling them to the ceramics industry, instead of spending money on having them taken away and dumped.
The process has been tested in the lab, and the university's Technology Transfer Office is now seeking industry partners to help finance a large-scale pilot project. And should ceramics manufacturers not have a need for all of the world's eggshells, scientists in India are working on a method of using them for carbon sequestration.
Source: University of Aveiro
Boeing reveals new spy phone
The Boeing Black boasts two SIM cards, allowing operators to switch between government and commercial networks (Photo: Boeing)
Boeing has stepped outside the field of aeronautics to develop a security focused smartphone – the Boeing Black. The device will be unavailable to the general public, being designed from the ground up to be the go-to device for the US Defense and Security communities. It offers what Boeing describes as “trusted access to data," allowing said agencies to carry out highly sensitive missions.
Product specifications
Boeing has made it clear that due to the covert nature of the device, the inner workings of the phone will not be made available to the general public. However some basic specifications for the spy phone have been released.
According to its product page, the Boeing Black runs a heavily customized version of Google's Android operating system and weighs in at 170 g (5.9 oz) with a 4.3 x 540 x 960-inch qHD display. The Bluetooth-enabled smartphone has room for two SIM cards, allowing the user to switch between government and commercial networks.
There's no word on how much internal storage the device will carry, but it does offer a microSD expansion slot. The handset is powered by dual 1.2 GHz ARM Cortex A9 CPUs, supports LTE connectivity and hosts a 1,590 mAh battery.
Whilst these specifications appear underwhelming when compared with flagship handsets such as the newly announced Samsung Galaxy S5, it's fair to say that the Black isn't aiming to compete with the cream of the Android crop.
The device was designed with modularity in mind. The back of the phone slides off to allow various modules such as additional sensing equipment or satellite connectivity, giving the phone a high level of flexibility for a secure mobile device.
Security features
Boeing Black is in effect a sealed unit, utilizing covered screws and epoxy glue to seal the casing. According to papers sent to the Federal Communications Commission, "Any attempt to break open the casing of the device would trigger functions that would delete the data and software contained within the device and make the device inoperable."
This also means that it is impossible to service or swap out components within the phone.
On top of these physical safety measures, the Boeing Black boasts a plethora of software security elements covering a wide range of functions. One such example of the data protection software utilized in Boeing Black is disk encryption, a system that effectively protects stored information by converting it into an unreadable code.
We reached out to Boeing for comment on the device, with the company simply stating that “Boeing Black delivers unique embedded hardware and software security solutions, operating system policy controls, and compatibility with leading mobile device management systems."
Due to the fact that the phone's target client base is the US intelligence and defense community, no price or release date has been announced by the aeronautics giant.
Top 10 Things You Can Upgrade with a Little Electronics Hacking
Rule #1 of DIY: Never settle for what you're given. You can upgrade and improve just about anything with a little knowledge and elbow grease, especially if you know a little about electronics. Here are 10 things in your home that you can beef up with a little soldering and DIY know-how. P
10. Your TV
You may have the coolest home theater on the block, but even that won't save you when your TV rebels with the latest celebrity gossip you don't want to hear. Take control of your TV with the Enough Already, a little DIY gadget that mutes your TV whenever it hears a word or phrase you've programmed it to watch out for—like "Justin Beiber" or "Twilight Saga." While you're at it, you can use an Arduino to automatically lower the volume if it gets above a certain threshold, like when excessively loud commercials come on.
9. Your Home Security
It may not be as foolproof as a true home security system, but you can make quite a few DIY burglar alarms for almost nothing. $2 gets you a tiny motion alarm that beeps if its moved, while a few more dollars will get you a motion-detecting camera or an SMS-equipped monitor. Heck, you can even build your own LoJack for your car at a fraction of the price. Of course, you can also do quite a bit with just a few webcams and some free software.P
8. Your Desk
If your workspace is starting to feel a little cluttered with gadgets, make them work with your desk. Instead of getting another power strip, build an outlet into the desk itself, or embed a USB hub for easy charging and peripheral connection. If you want to take it one step farther, you can add an inductive charging station or even build a computer inside the desk drawer. And, while you're at it, clean everything up by making your desk lamp cordless for under $20.P
7. Your Video Game Consoles
What's better than having a couple of video game systems in your living room? Not much, except maybe combining them into one mega system that can play nearly any game. If you're more of a retro gamer, you can do something similar (with much less work) by building an all-in-one retro gaming console inside an NES, inside a briefcase, or even inside a coffee table to mimic the old arcade systems you love so much.P
6. Your Cellphone Charger
If you want a really easy DIY project, try upgrading your wall outlets to charge USB devices. You can also build a super-simple portable USB charger in an Altoids tin. For a greener solution, make it solar-powered or charge it with the power of your bike pedaling. And, if you want to do away with wires altogether, we've shared a ton of options for modding your phone for wireless charging without the bulky "induction charger" case.
5. Your Transportation
Many of us may upgrade our phones every year to stay up-to-date, but it's a little harder to do that with cars. If your car's missing a feature you want, though, just add it yourself. Put in an auxiliary audio jack for only $3, or add Bluetooth capability for wireless streaming wherever you go. If you're prone to running red lights, you might also consider this GPS hack that warns you when red light cameras are near. And, if you don't have a car, you can still beef up your transportation with these bike upgrades.P
4. Your Headphones
We love headphone hacks, and if you're willing to dig into your DIY arsenal, you can mod the hardware in quite a few ways. If you have earbuds, you can add an inline remote control with just a little bit of work (and without ruining them). If you have a bigger set of headphones, adding removable cables can be really handy, or you could go wireless altogether and hack them for Bluetooth. Of course, a good pair of earmuffs can also make for a dandy noise-isolating pair of headphones, too.P
3. Your Light Switches
Turning on the lights manually is no fun. Instead, mod the lamps in your house to turn on with a wave of your hand, or with an old-school made-at-home clapper. Alternatively, control them with your voice, or set them up in the hallway for easy motion-controlled lights that illuminate your path to the bathroom. Whatever you can think of, it's probably possible.
2. Your Chores
Doing chores is for chumps. Luckily, an Arduino and a bit of code can automate a ton of chores for you: it can make the plants water themselves, it can feed the cat for you, or even rock your baby to sleep. Just make sure your parents/spouse/roommates don't find out what you're up to.
1. Your Home
A home of the future isn't as far off as science fiction makes it out to be. With a little DIY electronics hacking, you can automate your home to do just about anything: open the blinds when it's light, tell you who's at the door, make you coffee with a tweet, unlock your door with a text message, and oh-so-much more. It won't get you George Jetson's flying car, but you'll feel like a futuristic badass nonetheless.
Title image by Your lucky photo (Shutterstock)
The Archive of Interesting Code for programmers.
The archive of interesting codes (link)
The Archive of Interesting Code is an (ambitious) effort on my part to research, intuit, and code up every interesting algorithm and data structure ever invented. In doing so, I hope both to learn the mathematical techniques that power these technologies and to improve my skills as a programmer.
The examples on this site are in a variety of languages. I generally prefer to use C++ for algorithms, since the STL provides a great framework for expressing algorithms that work on a variety of data types. I code up most data structures in Java, both because the Collections framework allows them to be integrated in seamlessly with other applications and because automatic garbage collection simplifies some of the resource management. Every now and then I'll find an algorithm or data structure that is best represented in a different language like Haskell, in which case I'll forgo my usual language conventions.
Nanoparticle Opens the Door to Clean-Energy Alternatives
A transmission-electron microscope image of a collection of quasi-spherical nickel phosphide nanoparticles. A team led by Raymond Schaak of Penn State University has found that these nanoparticles can catalyze an important chemical reaction that generates hydrogen from water. Credit: Eric Popczun, Penn State University
13 June 2013 — Cheaper clean-energy technologies could be made possible thanks to a new discovery. Led by Raymond Schaak, a professor of chemistry at Penn State University, research team members have found that an important chemical reaction that generates hydrogen from water is effectively triggered -- or catalyzed -- by a nanoparticle composed of nickel and phosphorus, two inexpensive elements that are abundant on Earth. The results of the research will be published in the Journal of the American Chemical Society.
Schaak explained that the purpose of the nickel phosphide nanoparticle is to help produce hydrogen from water, which is a process that is important for many energy-production technologies, including fuel cells and solar cells. "Water is an ideal fuel, because it is cheap and abundant, but we need to be able to extract hydrogen from it," Schaak said. Hydrogen has a high energy density and is a great energy carrier, Schaak explained, but it requires energy to produce. To make its production practical, scientists have been hunting for a way to trigger the required chemical reactions with an inexpensive catalyst. Schaak noted that this feat is accomplished very well by platinum but, because platinum is expensive and relatively rare, he and his team have been searching for alternative materials. "There were some predictions that nickel phosphide might be a good candidate, and we had already been working with nickel phosphide nanoparticles for several years," Schaak said. "It turns out that nanoparticles of nickel phosphide are indeed active for producing hydrogen and are comparable to the best known alternatives to platinum."
Image showing hydrogen gas bubbling off of the surface of a nickel phosphide crystal. A team led by Raymond Schaak of Penn State University is studying nanoparticles made from nickel phosphide as a means to create cleaner energy technologies. Credit: Eric Popczun, Penn State University
To create the nickel phosphide nanoparticles, team members began with metal salts that are commercially available. They then dissolved these salts in solvents, added other chemical ingredients, and heated the solution to allow the nanoparticles to form. The researchers were able create a nanoparticle that was quasi-spherical -- not a perfect sphere, but spherical with many flat, exposed edges. "The small size of the nanoparticles creates a high surface area, and the exposed edges means that a large number of sites are available to catalyze the chemical reaction that produces hydrogen," Schaak explained.
The next step was for team members at the California Institute of Technology to test the nanoparticles' performance in catalyzing the necessary chemical reactions. Led by Nathan S. Lewis, the George L. Argyros Professor of Chemistry at the California Institute of Technology, the researchers performed these tests by placing the nanoparticles onto a sheet of titanium foil and immersing that sheet in a solution of sulfuric acid. Next, the researchers applied a voltage and measured the current produced. They found that, not only were the chemical reactions happening as they had hoped, they also were happening with a high degree of efficacy.
"Nanoparticle technology has already started to open the door to cheaper and cleaner energy that is also efficient and useful," Schaak said. "The goal now is to further improve the performance of these nanoparticles and to understand what makes them function the way they do. Also, our team members believe that our success with nickel phosphide can pave the way toward the discovery of other new catalysts that also are comprised of Earth-abundant materials. Insights from this discovery may lead to even better catalysts in the future."
In addition to Schaak and Lewis, other researchers who contributed to this study include Eric J. Popczun, Carlos G. Read, Adam J. Biacchi, and Alex M. Wiltrout from Penn State; and James R. McKone from the California Institute of Technology.
The research was funded by the U.S. National Science Foundation and the U.S. Department of Energy. The team has filed a patent application.
Seasonal Science: The Reasons for the Seasons
An astronomical activity from Science Buddies
Feb 20, 2014 |By Science Buddies
George Retseck
Introduction
Have you ever lived somewhere where you get to experience the full glory of all four seasons? If so, you know well the full blossoms and dramatic skies of spring; the long, sun-drenched days of summer; the trees shaking in crimson and gold in fall; and the sparkling snows of winter. But do you know why we have these seasons over and over again in a cycle as predictable as sunrise and sunset? It actually has to do with Earth's tilt. In this science activity you'll investigate how this tilt affects how the sun's rays strike our planet and create seasons.
Background
In Earth’s Northern Hemisphere summers are hot and filled with many hours of strong sunlight whereas winters are cold due to shortened daylight hours and weak sunlight. Why is this? One big part of the answer is that Earth is tilted on its axis. To visualize this axis, picture an imaginary stick piercing Earth from its North to South poles. Earth spins once around this axis every 24 hours. While spinning like this our planet also circles the sun in a big orbit, completing this loop in about 365 days.
This axis isn't straight up and down as Earth orbits around the sun, however. Instead, it is tilted at approximately 23 degrees and also remains fixed, always aligned in the same direction in space. This tilt changes how the sunlight hits Earth at a given location in its yearly orbit. When it is summer in the Northern Hemisphere, the top part of the axis (the North Pole) points more toward the sun, and the sun's rays shine more directly on the Northern Hemisphere (where the continents of North America, Europe and Asia as well as the northern parts of Africa and South America are located); at the same time in the Southern Hemisphere (Antarctica, Australia, most of South America and the southern third of Africa), where it's winter, the South Pole end of the axis is tipped away from the sun, and its rays hit that half of Earth on a slant.
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