Light, electrons, photons and contamination

Light, electrons, photons and contamination

Light, electrons, photons. The rider is interested in light that there is no doubt. It must be why we found a chemical in the Faculty of Natural Sciences and wander with him on these issues.
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By Leonardo Moledo

-You work with and photochemical air pollution. Why am I not a bit what this is?

-Tell a little story. My first thesis in silver on the photochemical reactions between gases (molecules in the atmosphere, but in a closed container). The photo is actually the study of chemical reactions that are related to the light: I was going through various stages until finally I devoted myself to the photochemistry of solids, or systems.

- And what he is doing now?

Two things. On the one hand, the study of reactions that occur with light in ways organized or ordered and on the other, we studied the chemical reactions that occur in the atmosphere through field work: we measured the concentration of pollutants and try to make models to predict how keep the thing going and how we can improve. That brings me almost to my roots: the relationship between particles and gases back to the relationship between gases. They are two completely different projects. Our activities in atmospheric chemistry are well known. But it is not our main line of inquiry.

- And what would prefer to speak?

-What is under press ...

Talk-time of light and the sound ...

-The example of the action of light on photosynthesis is organized systems: here we have light that is irradiated on the leaves, which contain chlorophyll and other pigments that are arranged to absorb light and channel the reaction center. Then, through the action of the center, the light is converted into carbohydrates, etcetera, etcetera. While this paradigm is the action, is not what we studied. We take some of that photosynthesis to create artificial systems that allow us to harness sunlight to produce certain substances. For example: there is a cancer treatment, photodynamic therapy is that, based on the introduction of a color in the body and irradiation in the area where the cancer. The dye is introduced in a general system and then it focuses on the area where the cancer is, so that when the dye that absorbs light is accumulated there, is excited. The dye is highly reactive, so as to effectively destroy the cell.

- Is it a therapy that is used?

In many countries do, here I have no reference was being used for experimentation. Now systems are being used a lot of nanoparticles, which are either themselves against reactive to light, or they incorporate dyes that are reactive. That is quite successful in the experimental field. To make the process more efficient, there must be a lot of dye molecules together. But this is a problem: the energy absorbed being together, is dissipated as heat from the reactions that are between them. The plants have solved the problem of organizing such a way that the concentration is very large, but the interactions between molecules are prevented to the maximum. A bit that is what we do, sometimes by very simple: take a solid, put it in a dye solution and we are left with a solid color, for example. Another way is to take a glass, put glass on an electrically charged polymer, we put up a load with the opposite color, then another layer of charged polymer and so on.

A sandwich-polymer and dye.

Something like that. The technique is called self layer by layer. Many people try to put the dye molecule in the specific location, which is very valuable. But we do not do this: try to find systems in which the molecules have to fall where they fall. Those are the two ways we are exploring, to put the largest possible amount of dye in a solid, either for a photodynamic therapy or to a photovoltaic cell works by absorbing energy in different regions of the spectrum. This can be achieved with different dyes, which absorb the largest number of regions of the spectrum. That is the strategy used by plants as well.

Come-a little to the intimacy of the action of light. We have a molecule that receives a photon, a particle of light. What about the photon?

-Molecules are made up of atoms, which themselves have nuclei and electrons. The molecules themselves are orbital, the atom: diffuse regions where the electrons. Externalities are the most involved in chemical reactions: when the molecule absorbs light, stir and move to a higher orbital.

- And there, what happens? How is that a photon in a jump to the upper layer?

The photon-electromagnetic field is in motion. The light has an electric field and magnetic field. In this case we are interested in the electric field that is oscillating. This field interacts with electrons, if the energy is reached, the photon is absorbed. By then, the interaction between the electron and the electric field is achieved by a molecule with an electron in a higher state. Why is this useful? It is more energy and more energy is allowed to give certain reactions that otherwise would not or would too slowly. This opens the way to energy storage. So do plants convert light energy and use that energy to generate compounds that otherwise can not be generated. The photon activates a molecule of chlorophyll, which triggers a cascade of reactions whose reactants are carbon dioxide and water, and its products are glucose and other carbohydrates.

And the idea is ...

-The idea is to excite as many molecules as possible with the widest possible spectrum of light and use these systems as building blocks for other things. However, one can have a photoelectric cell, which when absorbed light produces a charge separation, leaving the outside, closed the circuit and generates a current. This requires light of a certain energy, the energy at which the material absorbs. If one wants the material to absorb a different range of wavelengths, in a different area of the spectrum, what is done is to put a dye that is excited by absorbing photons, delivers an electron to the electrode and the electron is given turn out. Our particulitas be building blocks for this. Another example: photocatalysis.

-What is ...

-... a process whereby a semiconductor material (such as titanium dioxide) absorbs a photon, an electron loose and creates a vacancy. This electron can go into another molecule and the semiconducting molecule can receive electrons from the other side. The ability of these electron holes get so big that it can oxidize (remove electrons from) a bunch of molecules and destroy them, doing the reverse process of photosynthesis. Grab the material and convert it into carbon dioxide and water, which is very interesting for decontamination processes.

Well, because it talked about pollution, why I do not mind a bit of the other line of inquiry?

Ago as ten or fifteen years we started to work in collaboration with the Fundación Siglo XXI. I fell there for nostalgia, because it came from relationships with photochemical gases. We have learned since then what are the most important pollutants. What we wonder, too, is why we are not as bad as Mexico City or as Santiago de Chile.

But this may not be a chemical reason but for a reason ... weather, here we are surrounded by mountains.

Yes and no. One part of a series of primary pollutants (carbon monoxide, nitrogen monoxide, hydrocarbons) that if you have time, sunlight is converted into nitrogen dioxide and ozone, which are oxidants. These are the causes of smog, which is known in Mexico or in Santiago. There is no question of Meteorology: meteorology helps disperse pollutants and do not have time to react, or react further in other conditions. Weather is what happened in April last year, from where the fires took place in Buenos Aires Tigre everything was filled with an overwhelming humareda ten days.

-What I said is that the root chemistry course is, but why are neither James nor DF is that we are in an open city.

It is well. With a little objection. One thinks that the wind just sweeps. But if the wind sweeps, creeps. And what is produced here send it there. The wind dispersed. And not just the wind. That the wind that sweeps is a half-truth, because what it does is disperse.

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Three Cuban scientists, doctors in Physics, Chemistry and Health, Aurora Pérez Martínez, Aurora Pérez Álvarez Gramatges Mailing and Vera respectively, have now been payable Kovalievskaia Sofia Prize, awarded by the Foundation that bears the name of the great Russian researcher.

The institution, whose headquarters is the University of Arizona, encourages participation of women in developing countries in research projects, which gives a cash fund.

Aurora Pérez Martínez, of the Institute of Cybernetics, Mathematics and Physics laureate for his work was a dynamic source of magnetic field and dense autogravitante Quarks Star magnetized.

For its part Aurora Perez Gramatges, the Higher Institute of Applied Science and Technology, won the Design and characterization of self-organizing systems micelares analytical interest.

Work Mailing Álvarez Vera Institute of Tropical Medicine Pedro Kouri, entitled New evidence of the global development of dengue haemorrhagic fever during infection with dengue 3.

At the award ceremony attended by Neal and Ann Koblitz and Ismael Clark, president of the Kovalievskaia Foundation and the Academy of Sciences of Cuba, respectively.

In our country, the award is given each Kovalievskaia Sofia two years, and its winners are chosen from among those females who were recognized with the Award of the Academy of Sciences in Cuba two years earlier. Began given here since 2003 and so far have been 16 investigations.

Sofia Kovalievskaia born in Russia in the nineteenth century. It was the first woman in the world to receive a Ph.D. in Mathematics. Despite suffering discrimination because of gender, their research and contributions to science earned him several awards and a reputation throughout Europe.

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2009 La crisis reduce el consumo de productos del caucho a n 50 %. Los grandes mezcladores de caucho en España estan reduciendo hasta un 50 % la producción de sus productos. Estas situación tan drástica hace que más de uno se halle con dificultades económicas al no preveer una disminución tan brusca de la venta de sus productos.

The 2009 crisis reduces the consumption of products of an rubber 50%. Large rubber mixers in Spain are up to 50% by reducing the production of their products. This makes such a drastic situation over with a financial hardship is not expected to decline sharply as the sale of their products.

Die Krise 2009 reduziert den Verbrauch von Waren mit einem Gummi 50%. Große Gummi-Mischer in Spanien bis zu 50% durch die Reduzierung der Produktion ihrer Erzeugnisse. Dies macht eine solche drastische Situation mit einer finanziellen Notlage ist nicht zu erwarten, stark rückläufig, da der Verkauf ihrer Produkte.

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Concluye Cevisama 2009 aun 75 % de su capacidad y con numeros espacios vacios de expositores que no han asistido por culpa de la crisis. La exposición más internacional de cerámicas finaliza también con una disminución de los asistentes respecto el año anterior. Clíca aqui para ver fotos de expositores

	Concludes Cevisama 2009 even 75% full and empty spaces with numbers of exhibitors who have not attended because of the crisis. The most international ceramics exhibition ends with a decline in attendance regarding the previous year. Click here to see photos of exhibitors

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Basically, silicones that are or are intended to have contact with food must meet the following specifications:

1) Silicones have to transfer their constituents to foods in quantities that can harm people's health and cause an unacceptable change in the composition of the food or alter the characteristics organoléticas of it.

2) They must be manufactured according to a System for Quality Assurance (ISO 9002 for example) and under the terms set forth in facilitated in the listing document of the Resolution (substances, and authorized additives).

3) The interaction between the substances for the manufacture of silicones should not generate substances that cause damage in people.

4) To prevent the formation of cyclic polydimethylsiloxane with phenyl groups, can not be used as the starting substances, which have linear siloxanes and phenyl methyl groups in the same atom or containing two methyl groups on the same silicon atom (siloxanes and silicones, methyl, phenyl, dimethyl).

5) The migration / emission of any substance from the silicone into the food has to be as low as technically possible. The total quantity of substances that may migrate is 10 milligrams per square decimetre area of material or 60 milligrams per kilogram of food. This is considered as the limit of global migration and coincides with the limit imposed by the directive on plastics in contact with food.

6) It should meet the specific migration limits specified in the technical paper of the resolution on silicones.

7) Migration tests must be carried out following the directions of the Directives 82/711/EEC, 85/572/EEC, 2002/72/EC and its future amendments unless it is technically impossible because of the nature Material and the migration test.

8) It must ensure a proper labeling of the product, if necessary, pre by the user.

In the case of children's products made with silicone and intended to come into contact with food, as in the example of teats for a bottle, also has to comply with specific regulations, especially regarding the content of volatile metal migration and specific migration of certain antioxidants.

Quimica - Chemical: Masters de pigmentos de siliconas con aplicaciones en sellantes de siliconas, Holland Colours

Efficiency, flexibility, and cost-effectiveness Colouring sealants has never been this efficient. We offer our partners the most efficient and cost-effective colouring solutions for the four most common sealants on the market.
We’ve created colouring pastes that will give you the same outstanding performance in automatic or semi-automatic mixing systems. And they’re also suitable for manual mixing.
Colour Consistency You want to know that you will get the same colour with every production run, and that’s what you will get with Holland Colours sealant colorants.
Quality, Experience, and Service With a quarter century of experience in the market, we know and understand your needs. We’ve also worked with all the major suppliers of dosing equipment. Whether you need support selecting the appropriate product, you’re looking for a custom colour or a specific viscosity, or you need technical assistance with production, we stand ready to provide you with the service you need. Global Presence We’ve got a global network of sales and technical service offices. Ready to respond to your call. In person, if that’s what it takes.
For more information on colouring of various sealants click on: Silicone sealants Organic sealants Acrylic sealants Plasticizer-free silicone sealants

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	>>> Product Specifications MSDS
	MFIL - P(S) ( HTV Silicon Applications )
	End Properties Improves processibility of raw mixture. Offers resistance to heat aging. Minimises crape hardening. Provides superior resilence and compression set.
Packing Method	LDPE liners wrapped with laminated HDPE
Shipment	NET WEIGHT PER BAG (KGS)	SHIPMENT ( MT )
		TRUCK LOAD	CONTAINER LOAD
			UNPALLETISED		PALLETISED
	20.00	5.0	20’ FCL	40’ H.C.FCL	20’ FCL	40’ H.C. FCL
			4.75	11.0	3.84	9.60

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	>>> Product Specifications MSDS
Grades	MFIL - 300, ABSIL - 100(I)
	End Properties MFIL-300 Silica acts as a Micro-Rough surface, Improves Mold Release Prevents surface sticking of Plastic Films, Enhances Film Openability And Processibility Improves Film Optical Properties Prevents Plateout phenomena in PVC Formulations ABSIL-100(I) Can replace Imported Minerals / Fillers in Plastic Master Batches with Good Economy and Antiblocking effect.
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			TRUCK LOAD	CONTAINER LOAD
				UNPALLETISED		PALLETISED
				20’ FCL	40’ H.C.FCL	20’ FCL	40’ H.C. FCL
	MFIL -300	10.00	4.50	4.50	9.00	4.00	8.00
	ABSIL -100 (I)	25.00	9.00	13.00	26.00	12.80	25.60

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Holcosil IP

Cost? Colour consistency? Custom colours? Customer specific viscosity? There’s one answer — Holcosil IP. Holland Colours has the solution for colouring silicone sealants. With high pigment loading and excellent dispersion, so you can use less material and cut your costs. To give you a leg up on the competition.

Holcosil IP pastes are de-gassed, rheologically controlled, and highly suited for automatic dosing applications. But if you need a custom colour or if our standard viscosity is not appropriate to your application, we can produce a made-to-order colorant that will fit the bill. Holcosil IP is also used for colouring B-components or hardeners of RTV2 products.

Standard colours Click here to view our standard colours.

Custom colours Click here to tell us what you are looking for. One of our sales specialists will contact you to discuss the possibilities.

Here you can down load our technical flyer Coloring Solutions for Silicone Sealants (PDF)

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Responsive to your needs Fast turnaround — for orders under 200 kgs, shipment possible within 2 days Quantities from 1 kg Custom colours Available in FDA (Food and Drug Administration) and German BfR (Bundesinstitut für Risikobewertung)-compliant versions Suitable for high-end technical applications
Standard colours Click here to view our standard colours.
Custom colours Click here to tell us what you are looking for. One of our sales specialists will contact you to discuss the possibilities.
Here you can down load our technical flyer Coloring Silicone Rubbers (PDF)

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Great Lakes' Firemaster CP-44HF flame retardant was originally developed in 2003 to provide higher thermal stability and flow. With the movement to lead-free solder, the product has now been shown to offer improved blister resistance due to its compatibility with HTPA resins. Traditional flame retardants such as brominated polystyrene tend to form blisters on the part surface at the higher temperatures used during lead-free soldering. Blistering occurs because the flame retardant is not completely dispersed through the polymer, but clusters in flame retardant domains where moisture collects and then expands when exposed to high temperatures. Firemaster CP-44HF is a co-polymer of di- and tri-bromostyrene with glycidyl methacrylate. The methacrylate functionality allows greater bonding and compatibility of the flame retardant with the host resin, resulting in improved dispersion and elimination of the flame retardant domain, explains Mr. Andrews.

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