Cavitation bubbles

A research team at standford university is currently working in ArF lasser technics to induce cavitation in a gel surrounded by a liquid medium that might be used later in biological tissue. This is a great breakthrough for medicine since it could be used not only for regular surgery with more precision, but it could be used to eliminate cancer cells too. In the following link, is a full description of the research of standford´s research team: http://www.stanford.edu/~palanker/publications/excimer%20laser%20in%20gel.pdf

For more information about cavitation, I recomend the next video, which describe in a brief and easy way, what cavitation and cavitation bubbles are, and some possible applications for this.

Helio!

http://www.youtube.com/watch?v=tzecE6XDFgg&feature=BFa&list=UUZYTClx2T1of7BRZ86-8fow&lf=plcp

En el vídeo anterior se exponen algunas características y usos generales del helio, y también se habla sobre el inevitable déficit de helio al que los acercamos. A continuación se expone una breve historia del helio y sus usos.

"Helium, the second most abundant element in the universe, was discovered on the sun before it was found on the earth. Pierre-Jules-César Janssen, a French astronomer, noticed a yellow line in the sun's spectrum while studying a total solar eclipse in 1868. Sir Norman Lockyer, an English astronomer, realized that this line, with a wavelength of 587.49 nanometers, could not be produced by any element known at the time. It was hypothesized that a new element on the sun was responsible for this mysterious yellow emission. This unknown element was named helium by Lockyer.
The hunt to find helium on earth ended in 1895. Sir William Ramsay, a Scottish chemist, conducted an experiment with a mineral containing uranium called clevite. He exposed the clevite to mineral acids and collected the gases that were produced. He then sent a sample of these gases to two scientists, Lockyer and Sir William Crookes, who were able to identify the helium within it. Two Swedish chemists, Nils Langlet and Per Theodor Cleve, independently found helium in clevite at about the same time as Ramsay.
Helium makes up about 0.0005% of the earth's atmosphere. This trace amount of helium is not gravitationally bound to the earth and is constantly lost to space. The earth's atmospheric helium is replaced by the decay of radioactive elements in the earth's crust. Alpha decay, one type of radioactive decay, produces particles called alpha particles. An alpha particle can become a helium atom once it captures two electrons from its surroundings. This newly formed helium can eventually work its way to the atmosphere through cracks in the crust.
Helium is commercially recovered from natural gas deposits, mostly from Texas, Oklahoma and Kansas. Helium gas is used to inflate blimps, scientific balloons and party balloons. It is used as an inert shield for arc welding, to pressurize the fuel tanks of liquid fueled rockets and in supersonic windtunnels. Helium is combined with oxygen to create a nitrogen free atmosphere for deep sea divers so that they will not suffer from a condition known as nitrogen narcosis. Liquid helium is an important cryogenic material and is used to study superconductivity and to create superconductive magnets. The Department of Energy's Jefferson Lab uses large amounts of liquid helium to operate its superconductive electron accelerator."

For further reading:
"U.S. government agencies work to minimize damage due to helium-3 shortfall," Toni Feder, Physics Today October 2009, page 21
http://www.physicstoday.org/resource/1/phtoad/v62/i10/p21_s1?isAuthorize...
"Nation's helium reserve running on empty?" Leslie Tamura, Washington Post, Oct.11, 2010
http://education.jlab.org/itselemental/ele002.html

De lo mismo de abajo: Paint-On Solar Cells Developed

Imagine if the next coat of paint you put on the outside of your home generates electricity from light -- electricity that can be used to power the appliances and equipment on the inside.

A team of researchers at the University of Notre Dame has made a major advance toward this vision by creating an inexpensive "solar paint" that uses semiconducting nanoparticles to produce energy.

"We want to do something transformative, to move beyond current silicon-based solar technology," says Prashant Kamat, John A. Zahm Professor of Science in Chemistry and Biochemistry and an investigator in Notre Dame's Center for Nano Science and Technology (NDnano), who leads the research.

"By incorporating power-producing nanoparticles, called quantum dots, into a spreadable compound, we've made a one-coat solar paint that can be applied to any conductive surface without special equipment."

The team's search for the new material, described in the journal ACS Nano, centered on nano-sized particles of titanium dioxide, which were coated with either cadmium sulfide or cadmium selenide. The particles were then suspended in a water-alcohol mixture to create a paste.

When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity.

"The best light-to-energy conversion efficiency we've reached so far is 1 percent, which is well behind the usual 10 to 15 percent efficiency of commercial silicon solar cells," explains Kamat.

"But this paint can be made cheaply and in large quantities. If we can improve the efficiency somewhat, we may be able to make a real difference in meeting energy needs in the future."

"That's why we've christened the new paint, Sun-Believable," he adds.

Kamat and his team also plan to study ways to improve the stability of the new material.

NDnano is one of the leading nanotechnology centers in the world. Its mission is to study and manipulate the properties of materials and devices, as well as their interfaces with living systems, at the nano-scale.

This research was funded by the Department of Energy's Office of Basic Energy Sciences.

References:

University of Notre Dame (2011, December 21). Paint-on solar cells developed. ScienceDaily. Retrieved February 27, 2012, from

Sun-Believable Solar Paint. A Transformative One-Step Approach for Designing Nanocrystalline Solar Cells

Este está bien coqueto :D

A transformative approach is required to meet the demand of economically viable solar cell technology. By making use of recent advances in semiconductor nanocrystal research, we have now developed a one-coat solar paint for designing quantum dot solar cells. A binder-free paste consisting of CdS, CdSe, and TiO₂ semiconductor nanoparticles was prepared and applied to conducting glass surface and annealed at 473 K. The photoconversion behavior of these semiconductor film electrodes was evaluated in a photoelectrochemical cell consisting of graphene–Cu₂S counter electrode and sulfide/polysulfide redox couple. Open-circuit voltage as high as 600 mV and short circuit current of 3.1 mA/cm² were obtained with CdS/TiO₂–CdSe/TiO₂ electrodes. A power conversion efficiency exceeding 1% has been obtained for solar cells constructed using the simple conventional paint brush approach under ambient conditions. Whereas further improvements are necessary to develop strategies for large area, all solid state devices, this initial effort to prepare solar paint offers the advantages of simple design and economically viable next generation solar cells.

References:

Sun-Believable Solar Paint. A Transformative One-Step Approach for Designing Nanocrystalline Solar Cells

Matthew P. Genovese, Ian V. Lightcap, and Prashant V. Kamat

ACS Nano 2012 6 (1), 865-872 [Online] http://pubs.acs.org/doi/abs/10.1021/nn204381g

Nanoscale Plasmonic Interferometers for Multispectral, High-Throughput Biochemical Sensing

Report the design, fabrication, and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form two-arm, three-beam, planar plasmonic interferometers. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400–800 nm). A wavelength sensitivity between 370 and 630 nm/RIU (RIU, refractive index units), a relative intensity change between 10³ and 10⁶ %/RIU, and a resolution of 3 × 10^–7 in refractive index change were experimentally measured using typical sensing volumes as low as 20 fL. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time, and extremely compact biochemical sensors.

References:

Nanoscale Plasmonic Interferometers for Multispectral, High-Throughput Biochemical Sensing

Jing Feng, Vince S. Siu, Alec Roelke, Vihang Mehta, Steve Y. Rhieu, G. Tayhas R. Palmore, and Domenico Pacifici

Nano Letters 2012 12 (2), 602-609 [on line] http://pubs.acs.org/doi/abs/10.1021/nl203325s

Water Oxidation Catalysis: Influence of Anionic Ligands upon the Redox Properties and Catalytic Performance of Mononuclear Ruthenium Complexes

Aiming at highly efficient molecular catalysts for water oxidation, a mononuclear ruthenium complex Ru^II(hqc)(pic)₃ (1; H₂hqc = 8-hydroxyquinoline-2-carboxylic acid and pic = 4-picoline) containing negatively charged carboxylate and phenolate donor groups has been designed and synthesized. As a comparison, two reference complexes, Ru^II(pdc)(pic)₃ (2; H₂pdc = 2,6-pyridine-dicarboxylic acid) and Ru^II(tpy)(pic)₃ (3; tpy = 2,2′:6′,2″-terpyridine), have also been prepared. All three complexes are fully characterized by NMR, mass spectrometry (MS), and X-ray crystallography. Complex 1 showed a high efficiency toward catalytic water oxidation either driven by chemical oxidant (Ce^IV in a pH 1 solution) with a initial turnover number of 0.32 s^–1, which is several orders of magnitude higher than that of related mononuclear ruthenium catalysts reported in the literature, or driven by visible light in a three-component system with [Ru(bpy)₃]²⁺ types of photosensitizers. Electrospray ionization MS results revealed that at the Ru^III state complex 1 undergoes ligand exchange of 4-picoline with water, forming the authentic water oxidation catalyst in situ. Density functional theory (DFT) was employed to explain how anionic ligands (hqc and pdc) facilitate the 4-picoline dissociation compared with a neutral ligand (tpy). Electrochemical measurements show that complex 1 has a much lower E(Ru^III/Ru^II) than that of reference complex 2 because of the introduction of a phenolate ligand. DFT was further used to study the influence of anionic ligands upon the redox properties of mononuclear aquaruthenium species, which are postulated to be involved in the catalysis cycle of water oxidation.

References:

Water Oxidation Catalysis: Influence of Anionic Ligands upon the Redox Properties and Catalytic Performance of Mononuclear Ruthenium Complexes (27 de Febrero)

Lianpeng Tong, Ying Wang, Lele Duan, Yunhua Xu, Xiao Cheng, Andreas Fischer, Mårten S. G. Ahlquist, and Licheng Sun

Inorganic Chemistry Article ASAP [Online] http://pubs.acs.org/doi/abs/10.1021/ic201348u

Detection of Charge Storage on Molecular Thin Films of Tris(8-hydroxyquinoline) Aluminum (Alq3) by Kelvin Force Microscopy: A Candidate System for Hig

Retention and diffusion of charge in tris(8-hydroxyquinoline) aluminum (Alq₃) molecular thin films are investigated by injecting electrons and holes via a biased conductive atomic force microscopy tip into the Alq₃ films. After the charge injection, Kelvin force microscopy measurements reveal minimal changes with time in the spatial extent of the trapped charge domains within Alq₃ films, even for high hole and electron densities of >10¹² cm^–2. We show that this finding is consistent with the very low mobility of charge carriers in Alq₃ thin films (<10^–7 cm²/(Vs)) and that it can benefit from the use of Alq₃ films as nanosegmented floating gates in flash memory cells. Memory capacitors using Alq₃ molecules as the floating gate are fabricated and measured, showing durability over more than 10⁴ program/erase cycles and the hysteresis window of up to 7.8 V, corresponding to stored charge densities as high as 5.4 × 10¹³ cm^–2. These results demonstrate the potential for use of molecular films in high storage capacity nonvolatile memory cells.

Reference:

Detection of Charge Storage on Molecular Thin Films of Tris(8-hydroxyquinoline) Aluminum (Alq3) by Kelvin Force Microscopy: A Candidate System for High Storage Capacity Memory Cells ( 27 de febrero)

Sarah Paydavosi, Katherine E. Aidala, Patrick R. Brown, Pouya Hashemi, Geoffrey J. Supran, Timothy P. Osedach, Judy L. Hoyt, and Vladimir Bulović

Nano Letters Article ASAP [online] http://pubs.acs.org/doi/abs/10.1021/nl203696v