Tag Archives: UDEM

Université de Montréal (Canada) collaborates with University of Houston (US) for a new theory and better solar cells

Solar cell efficiency is not good as researchers from  l’Université de Montréal (UdeM, located in Quebec, Canada) and the University of Houston (UH, located Texas, US) note in a Jan. 29, 2014 joint UH/UdeM news release written by Lisa Merkl (UH) on EurekAlert,

“Scientists don’t fully understand what is going on inside the materials that make up solar cells. We were trying to get at the fundamental photochemistry or photophysics that describes how these cells work,” Bittner said [Eric Bittner, a John and Rebecca Moores Professor of Chemistry and Physics in UH’s College of Natural Sciences and Mathematics,].

Solar cells are made out of organic semiconductors – typically blends of materials. However, solar cells made of these materials have about 3 percent efficiency. Bittner added that the newer materials, the fullerene/polymer blends, only reach about 10 percent efficiency.

“There is a theoretical limit for the efficiency of the ideal solar cell – the Shockley-Queisser limit. The theory we published describes how we might be able to get above this theoretical limit by taking advantage of quantum mechanical effects,” Bittner said. “By understanding these effects and making use of them in the design of a solar cell, we believe you can improve efficiency.”

Silva [Carlos Silva, an associate professor at the Université de Montréal and Canada Research Chair in Organic Semiconductor Materials] added, “In polymeric semiconductors, where plastics form the active layer of solar cells, the electronic structure of the material is intimately correlated with the vibrational motion within the polymer chain. Quantum-mechanical effects due to such vibrational-electron coupling give rise to a plethora of interesting physical processes that can be controlled to optimize solar cell efficiencies by designing materials that best exploit them.”

Unfortunately, there’s no more information about this model other than this (from the news release),

“Our theoretical model accomplishes things that you can’t get from a molecular model,” he [Bittner] said. “It is mostly a mathematical model that allows us to look at a much larger system with thousands of molecules. You can’t do ordinary quantum chemistry calculations on a system of that size.”

The calculations have prompted a series of new experiments by Silva’s group to probe the outcomes predicted by their model.

Bittner and Silva’s next steps involve collaborations with researchers who are experts in making the polymers and fabricating solar cells.

Here’s a link to and a citation for the paper,

Noise-induced quantum coherence drives photo-carrier generation dynamics at polymeric semiconductor heterojunctions by Eric R. Bittner & Carlos Silva. Nature Communications 5, Article number: 3119 doi:10.1038/ncomms4119 Published 29 January 2014

This article is behind a paywall although you can get a free preview via ReadCube Access.

Lab tests show silver nanoparticles in cream blocks HIV entry for up to 72 hours

Since at least 2005 (the article reference will be given later in this posting), researchers have been aware that silver nanoparticles can block the HIV virus from entering a cell. The latest work in this area has resulted in a vaginal cream laced with silver nanoparticles according to a Jan. 28, 2014 news item on ScienceDaily,

Lara Villegas [Humberto Lara Villegas, specialist in nanoparticles and virology from the University of Monterrey, Mexico (UDEM)] explained that HIV makes its entry to immune cells (CD4) of the organism with the aid of a protein known as GP120, which allows the virus adherence to the cells. This same principle is used by silver nanoparticles to attach themselves to this protein and block it, turning the virus inactive.

The Mexican researcher informed that the cream has been tested in samples of human tissue and has proven the efficiency of silver nanoparticles to avoid the transmission of the virus through cervical mucous membrane.

The Jan. 28, 2014 Investigación y Desarrollo news release (on the Alpha Gallileo website), which originated the news item, provides additional details from Lara Villegas’ perspective,

The researcher from UDEM, who has worked in Israel and The United States, assured that after applied, the cream starts to work in less than a minute, and has an effective protection of up to 72 hours.

Given that the function of this product is the inactivation of the virus, although this is a vaginal cream, will also protect the sexual partner.

“Normally – he highlighted-, the medication used against the virus act within the cell to avoid its replication. This is a very different case, given that the nanoparticle goes directly against the HIV and no longer allows its entry to the cell”.

So far, no toxicity of the silver nanoparticles has been reported, although he added that research is yet to be performed to evaluate the possible side effects of silver properties.

“Right now, I am certain that this microbicide is going to avoid the virus entering the organism, but I cannot yet assure that is totally harmless, because the clinical trials are a long and expensive process”, the researched added.

He exposed that the use of gels are usually accompanied by irritation, which favors the entry of the virus, which is why the cream was enriched with an anti-inflammatory effect.

Currently, with the obtained results, researchers will proceed to perform experimentation in mice that accept human cells, to later begin with human clinical trials.

He added that this cream could prevent the transmition of other sexually acquired virus like the Human Papilloma Virus (HPV). Likewise, he considered that silver nanoparticles could be used to combat bacteria transmitted the same way.

As promised here’s a citation for and a link to the 2005 paper; I haven’t found any references in my admittedly brief search for a paper about this latest work,,

Interaction of silver nanoparticles with HIV-1 by Jose Luis Elechiguerra, Justin L Burt, Jose R Morones, Alejandra Camacho-Bragado, Xiaoxia Gao, Humberto H Lara, and Miguel Jose Yacaman. Journal of Nanobiotechnology 2005, 3:6  doi:10.1186/1477-3155-3-6

This paper is open access.

Here’s  the Investigación y Desarrollo website which seems to act as a hub for research in Mexico. Note: You will need Spanish language skills to fully utilize this site.