1. a fatal disease of cattle that affects the central nervous system. 4. the small projection of a mammary gland. 8. the act of slowing down or falling behind. 11. a drug combination found in some over - the - counter headache remedies ( aspirin and phenacetin and caffeine ). 12. goddess of the dead and queen of the underworld. 13. a hospital unit staffed and equipped to provide intensive care. 14. a police officer who investigates crimes. 15. divulge information or secrets. 16. a logarithmic unit of sound intensity equal to 10 decibels. 17. a radioactive element of the actinide series. 19. a range of mountains ( usually with jagged peaks and irregular outline ). 24. open - heart surgery in which the rib cage is opened and a section of a blood vessel is grafted from the aorta to the coronary artery to bypass the blocked section of the coronary artery and improve the blood supply to the heart. 25. a piece of furniture that provides a place to sleep. 27. resinlike substance secreted by certain lac insects. 29. a family of sino - tibetan languages spoken in southeastern asia. 31. a highly unstable radioactive element ( the heaviest of the halogen series ). 34. an official prosecutor for a judicial district. 35. a soft silvery metallic element of the alkali earth group. 36. ( greek mythology ) goddess of the earth and mother of cronus and the titans in ancient mythology. 38. the protoplasm of the germ cells that contains chromosomes and genes. 41. the blood group whose red cells carry both the a and b antigens. 42. a summary that repeats the substance of a longer discussion. 46. aircraft landing in bad weather in which the pilot is talked down by ground control using precision approach radar. 47. call upon in supplication. 49. ( irish ) mother of the tuatha de danann. 50. united states liquid unit equal to 4 quarts or 3. 785 liters. 51. a condition ( mostly in boys ) characterized by behavioral and learning disorders. 52. a strategically located monarchy on the southern and eastern coasts of the arabian peninsula. 53. a loose sleeveless outer garment made from aba cloth. 1. a chadic language spoken south of lake chad. 2. a detailed description of design criteria for a piece of work. 3. ( computer science ) a coding system that incorporates extra parity bits


sleeveless outer garment made from aba cloth. 1. a chadic language spoken south of lake chad. 2. a detailed description of design criteria for a piece of work. 3. ( computer science ) a coding system that incorporates extra parity bits in order to detect errors. 4. a bachelor ' s degree in theology. 5. the fatty flesh of eel. 6. by bad luck. 7. a sock with a separation for the big toe. 8. a small faint zodiacal constellation in the southern hemisphere. 9. sour or bitter in taste. 10. a russian prison camp for political prisoners. 18. a person forced to flee from home or country. 20. liquid containing proteins and electrolytes including the liquid in blood plasma and interstitial fluid. 21. not divisible by two. 22. english essayist ( 1775 - 1834 ). 23. a white metallic element that burns with a brilliant light. 26. ( akkadian ) god of wisdom. 28. a compartment in front of a motor vehicle where driver sits. 30. the sixth month of the civil year. 32. united states abolitionist ( 1786 - 1865 ). 33. a bantu language spoken by the chaga people in northern tanzania. 37. in bed. 38. being ten more than one hundred ninety. 39. someone who works ( or provides workers ) during a strike. 40. the arch of bone beneath the eye that forms the prominence of the cheek. 43. the capital and largest city of japan. 44. a rotating disk shaped to convert circular into linear motion. 45. ( irish ) mother of the ancient irish gods. 46. a heavy brittle diamagnetic trivalent metallic element ( resembles arsenic and antimony chemically ). 48. a ductile silvery - white ductile ferromagnetic trivalent metallic element of the rare earth group.


new solar cell gives its " 110 percent " in efficiency december 20, 2011 6 : 23 pm comment ( s ) - last by like tebow, these new solar cells are giving their " 110 percent " week in and week out. gains to quantum efficiency could yield around a 35 percent gain in conversion efficiency, the key metric using quantum dots - - tiny nanometer scale semiconductor crystals - - researchers at the u. s. national renewable energy laboratory have cracked an important physical barrier and achieved levels of performance long considered impossible for a solar cell. i. giving its 110 percent the special design used by the team utilized quantum dot nanocrystals in the 1 - 20 nm range. the nanocrystals were composed of lead selenide treated with ethanedithol and hydrazine. the photon - harvesting quantum dot - populated plane was sandwiched between a nanostructured zinc oxide layer and a thin gold electrode. a top layer was formed using a transparent conductor. the overall design is in line with the " thin - film " methodology, which is currently rising in commercial production. thin film cells tend to rely on scarce ( i. e. expensive on a per mass basis ) resources, such as rare earth metals. however, they use so little of them - - given the low mass of the thin film - - that they are not significantly more expensive than existing polycrystalline silicon cells. generally, the only major extra cost to thin film is the initial cost of shifting the production technology. the new nrel cell shatters the quantum efficiencies of previous designs, posting a peak external quantum efficiency of 114 ± 1 % and a peak internal quantum efficiency of 130 %. in order to understand these numbers and how any power efficiency device can be more than " 100 percent " efficient, you must understand the meaning of quantum efficiency ( qe ), which is overall quite different, but related to conversion efficiency ( which will be over 100 percent - - or even to 100 percent - - in traditional physics ). the new cell is a thin film design. [ image source : nrel ] quantum efficiency is a measure of how many electrons come out of a cell for every photon that goes into the cell. traditional silicon solar cells can achieve near 100 percent quantum efficiency at around 600 nm, but drop to around 80 percent on either end of the 500 - 1000 nm range ( visible light is 380 to 740 nm ). what this means is that the perfect " color " of light for silicon cells is orangish, while purple light can


but drop to around 80 percent on either end of the 500 - 1000 nm range ( visible light is 380 to 740 nm ). what this means is that the perfect " color " of light for silicon cells is orangish, while purple light can have a less than 45 percent conversion rate. as white light ( sunlight ) is a mixture of different wavelengths, the lower quantum efficiency of certain parts of the spectrum leads to lower average quantum efficiency. external efficiency directly uses the number of input photons and the number of output electrons from a device. internal efficiency, by contrast, uses theory to adjust these numbers to account for losses due to reflection and absorption. we took the liberty of borrowing ( fair use clause title 17 > chapter 1 > § 107 ) the charts for their 0. 72 ev bandgap cell ( their best - performing design ) and comparing it to a traditional pc silicon cell, adding a helpful reference that shows what evs roughly correspond to in the visible light range : comparing the external quantum efficiencies of the new nrel design ( top ) and the ps silicon design ( bottom ) over the visible light range ( middle bar ), we see that the new cell is slightly less efficient in capturing red - end light, but is much more efficient in capturing blue - end light. ( the black line in bottom graph and the blue line in the top right graph are the internal qes. ) overall this could grant up to a 35 percent efficiency gain versus today ' s standard ps silicon cells, according to the paper ' s authors. ii. you " cannot change the laws of physics " - - so pick a better law! the better blue - range performance comes thanks to multiple exciton generation ( meg ), a unique quantum effect, which like other oddball quantum effects, occurs at an extremely small scale. in an meg scenario, a single photon hits an atom, but rather than simply knocking off one electron via the formation of an " exciton " ( an electron / hole pair ), it puts multiple electrons into the flow. meg - - multiple exciton generation - - bends the traditional laws of physics. [ image source : los alamos science & tech mag. / u. s. department of energy ' s nnsa ] the exact quantum mechanics of this phenomena are being debated by physics. currently the three leading hypotheses are : - - the high energy exciton ( " x " ) becomes a " multi " - x, decaying through a dense range of multi - x


of this phenomena are being debated by physics. currently the three leading hypotheses are : - - the high energy exciton ( " x " ) becomes a " multi " - x, decaying through a dense range of multi - x states. - - a mixed " virtual " state consisting of multi - x and x ( think superposition ) is triggered by photon energetic absorption. - - photon absorption creates standard x, but in the special material x waffles back and forth, switching identity from x to multi - x and back, slowly dropping in energy, in the process. without meg, no solar cell can have more than a 100 percent internal or external qe. hence no traditional solar cell has had greater than a 100 percent qe, even at its optimal part of the spectrum ( e. g. orange light for silicon cells ). this means that the overall efficiency ( ce ) of a traditional cell - - even if perfectly optimized - - would not exceed 32 percent. cumulatively this 100 / 32 ( qe / ce ) limit is named the shockley - queisser limit after its discoverers ( s - q limit, for short ). as scotty would say " you cannot change the laws of physics. " but sometimes you have your cake and eat it to, if only you find the right quirk in complex and poorly understood physics of our universe. that ' s fundamentally what has been done here. meg was first theorized by nrel researcher arthur j. nozik, ph. d back in 2001, and was later confirmed to work in quantum dots, thanks to their special scale. this method is also known as " hot carrier generation ". using this quantum effect, later proved in the laboratory, the s - q performance barrier could be shattered. a useful property of quantum dots, is that their size determines their band gap, and hence the efficiency. thus building the " perfect " meg cell is simply a matter of picking the right size dots. as the bandgap tends to decrease as the quantum dot size and efficiency increase, the trick is to pick a quantum dot that is as big as possible, without losing the quantum effects. quantum dots don ' t just look pretty, they have some handy physics quirks too! [ image source : elec - intro ] quantum dots also generate electron / hole pairs easier, with room temperature being enough excite ( generate electricity ) in some quantum dot materials. the most recent paper was [ abstract ] in the peer - reviewed journal


[ image source : elec - intro ] quantum dots also generate electron / hole pairs easier, with room temperature being enough excite ( generate electricity ) in some quantum dot materials. the most recent paper was [ abstract ] in the peer - reviewed journal, with matthew c. beard taking the distinction of senior author and octavi e. semonin the distinction of being first author. professor novik was listed second to last, after four additional nrel colleagues. iii. third generation solar cells - - finally a solar tech. worth investing in " first " and " second " generation solar cells use various bulk semiconductors such as silicon, cadmium telluride, or copper indium gallium ( di ) selenide, which are then mixed with third, fourth, and fifth column ( in the periodic table ) elements to improve performance. ideally quantum dot cells could be combined with these traditional thin - film semiconductor cell designs, or applied using a mixture of nanocrystalline quantum dots optimized for different wavelengths. either methodology could yield an optimized " third " generation ( aka. next generation ) design. such a cell would enjoy the best of both worlds - - silicon cells ' excellent red range performance, along with quantum dots excellent performance on the higher end ( blue ) of the visible light spectrum. one approach to make a third generation ultra - efficient cell is to use a mixture of wavelength optimized quantum dots. [ image source : los alamos science & tech mag. / u. s. department of energy ' s nnsa ] while quantum dots are generally thought to be amenable to thin film cell " roll - to - roll " printing processes, the precise methods to do this on a mass production scale still have to be ironed out. furthermore, the quantum dot cells measured in this study exhibited a pretty low 4. 5 percent efficiency. while that sounds quite bad, it ’ s largely a result of the lower amount of quantum dots used in the absorbing layer. if quantum dot deposition techniques can be refined, the aforementioned " third " generation mixed cell could be finally realized. if somebody is going to do that, it will probably be professor nozik ' s team at the nrel. after all, they ' re who first discovered how to play the grand meg prank on the laws of physics in the first place. with these third generation solar cells, the technology may finally have the legs under it to compete with cheaper power generation methods ( e. g. carbon - based fuels and nuclear energy


password passwords are the combination locks used to protect our computer accounts. it goes without saying that giving out our combination or leaving the lock unlatched ( i. e. walking away from a logged on computer ), compromises our security. however, technology provides ways for people to obtain our combination even if we aren ' t careless. to thwart such misuse, we must choose complex combinations. there are three elements to a complex combination : 1. it can ' t be obvious. that is, it can ' t exist in an attack dictionary. * every word in an english language dictionary can be tried in minutes. attack dictionaries also include names, common misspellings, words with numbers, and other commonly used passwords. you also don ' t want the password to have any personal significance to you... your dog ' s name for example. using a dictionary word for a password is like using a locker number for a combination. 2. it can ' t be a short * a combination lock with a two number combination wouldn ' t protect very well. anything less than an eight character password is like having a such a combination. it simply won ' t hold up for long on the network. 3. it can ' t be made up of just a few characters * a combination lock with only ten numbers on the dial isn ' t as effective as one with fifty. using just lower case letters is like limiting a combination lock to ten numbers. on systems that support them, passwords should contain at least one of each of the following characters : o uppercase letters ( a - z ) o lowercase letters ( a - z ) o numbers ( 0 - 9 ) o punctuation marks (! @ # $ % ^ & * ( ) _ + = - ) etc. different systems have different capabilities. some will not let you use all the strength features mentioned here. when you get an account or change your password on a system, you should be given instructions on any limitations. how, you may ask, am i ever going to remember such a complicated password? * pick a sentence that reminds you of the password. for example : o if my car makes it through 2 semesters, i ' ll be lucky ( imcmit2s, ibl ) o only bill gates could afford this $ 70. 00 textbook ( obgcat $ 7t ) o what time is my accounting class in showker 240? ( wtimacis2? ) * if you absolutely have to, record it in


you have been there before. the best part of any professional development activity is the collaboration with other teachers. hearing the struggles and successes of others helps us to articulate our own ideas and spark new excitement in our own curriculum. we hope to strengthen the community of chemistry educators and provide a place for discussion and collaboration right here at this site. summer is one of my favorite times as a teacher! like most teachers i like to take a little time away from school, but, once i ' ve rested a bit, its my favorite time to do research as well. i encourage you to take time this summer to explore labs and activities that you think may work for your classroom, but just didn ' t have time to examine with your busy teaching schedule. call for symposia and workshops for the 23rd bcce at grand valley state university – greener on the grand : empowering chemical educators for a greener tomorrow, august 3 – 7, 2014 i ’ d like to report on one of the end - of - year research projects that two of my general chemistry students completed during class this year. if you ’ d like read more about these end - of year research projects in general, click here. wow! talk about an interesting idea! a very neat experiment, called “ hydroglyphics ”, has been published by philseok kim, jack alvarenga, joanna aizenberg and raymond sleeper in the journal of chemical education. i came across a simple, yet interesting experiment that was first described by elizabeth sumner walter in 2001. she merely had students pour water into a dish containing some gobstoppers candies. i showed this experiment to some of my college chemistry students while they were workin inquiry is a fluid concept. there are some truly fabulous activities on grand valley state university ' s target inquiry ( ti ) website ( www. gvsu. edu / targetinquiry ). yes, i am biased as i was part of the first ti cohort, but there are several labs now that were written later and they, too, are terrific.