sábado, 30 de junio de 2018

MIT: New coatings make natural fabrics waterproof

Fabrics that resist water are essential for everything from rainwear to military tents, but conventional water-repellent coatings have been shown to persist in the environment and accumulate in our bodies, and so are likely to be phased out for safety reasons. That leaves a big gap to be filled if researchers can find safe substitutes.
Now, a team at MIT has come up with a promising solution: a coating that not only adds water-repellency to natural fabrics such as cotton and silk, but is also more effective than the existing coatings. The new findings are described in the journal Advanced Functional Materials, in a paper by MIT professors Kripa Varanasi and Karen Gleason, former MIT postdoc Dan Soto, and two others.
“The challenge has been driven by the environmental regulators” because of the phaseout of the existing waterproofing chemicals, Varanasi explains. But it turns out his team’s alternative actually outperforms the conventional materials.
“Most fabrics that say ‘water-repellent’ are actually water-resistant,” says Varanasi, who is an associate professor of mechanical engineering. “If you’re standing out in the rain, eventually water will get through.” Ultimately, “the goal is to be repellent — to have the drops just bounce back.” The new coating comes closer to that goal, he says.
Comparison of droplets on a coated surface (left) and an untreated one (right). (Varanasi and Gleason research groups)
Because of the way they accumulate in the environment and in body tissue, the EPA is in the process of revising regulations on the long-chain polymers that have been the industry standard for decades. “They’re everywhere, and they don’t degrade easily,” Varanasi says.
The coatings currently used to make fabrics water repellent generally consist of long polymers with perfluorinated side-chains. The trouble is, shorter-chain polymers that have been studied do not have as much of a water-repelling (or hydrophobic) effect as the longer-chain versions. Another problem with existing coatings is that they are liquid-based, so the fabric has to be immersed in the liquid and then dried out. This tends to clog all the pores in the fabric, Varanasi says, so the fabrics no longer can breathe as they otherwise would. That requires a second manufacturing step in which air is blown through the fabric to reopen those pores, adding to the manufacturing cost and undoing some of the water protection.
Research has shown that polymers with fewer than eight perfluorinated carbon groups do not persist and bioaccumulate nearly as much as those with eight or more — the ones most in use. What this MIT team did, Varanasi explains, is to combine two things: a shorter-chain polymer that, by itself, confers some hydrophobic properties and has been enhanced with some extra chemical processing; and a different coating process, called initiated chemical vapor deposition (iCVD), which was developed in recent years by co-author Karen Gleason and her co-workers. Gleason is the Alexander and I. Michael Kasser Professor of Chemical Engineering and associate provost at MIT. Credit for coming up with the best short-chain polymer and making it possible to deposit the polymer with iCVD, Varanasi says, goes primarily to Soto, who is the paper’s lead author.
Using the iCVD coating process, which does not involve any liquids and can be done at low temperature, produces a very thin, uniform coating that follows the contours of the fibers and does not lead to any clogging of the pores, thus eliminating the need for the second processing stage to reopen the pores. Then, an additional step, a kind of sandblasting of the surface, can be added as an optional process to increase the water repellency even more. “The biggest challenge was finding the sweet spot where performance, durability, and iCVD compatibility could work together and deliver the best performance,” says Soto.
Testing of the coated surfaces shows that it gets a perfect score on a standard rain-repellancy test. The coatings are suited for substrates as diverse as fabrics, paper, and nanotextured silicon. (Varanasi and Gleason research groups)
The process works on many different kinds of fabrics, Varanasi says, including cotton, nylon, and linen, and even on nonfabric materials such as paper, opening up a variety of potential applications. The system has been tested on different types of fabric, as well as on different weave patterns of those fabrics. “Many fabrics can benefit from this technology,” he says. “There’s a lot of potential here.”
The coated fabrics have been subjected to a barrage of tests in the lab, including a standard rain test used by industry. The materials have been bombarded not only with water but with various other liquids including coffee, ketchup, sodium hydroxide, and various acids and bases — and have repelled all of them well.
The coated materials have been subjected to repeated washings with no degradation of the coatings, and also have passed severe abrasion tests, with no damage to the coatings after 10,000 repetitions. Eventually, under severe abrasion, “the fiber will be damaged, but the coating won’t,” he says.
The team, which also includes former postdoc Asli Ugur and Taylor Farnham ’14, SM ’16, plans to continue working on optimizing the chemical formula for the best possible water-repellency, and hopes to license the patent-pending technology to existing fabric and clothing companies. The work was supported by MIT's Deshpande Center for Technological Innovation.

Source:
http://news.mit.edu/2018/coatings-make-natural-fabrics-waterproof-0629

Demostrado: Las carnes rojas y procesadas producen cancer.

Mala noticia para los amantes del jamón (entre los que me incluyo) y las carnes.

Si bien mucha gente desconocía que la OMS incluyó hace poco las carnes rojas como potencialmente cancerígenas y las procesadas como probablemente cancerígenas, en marzo de 2018 se ha publicado en último informe de la agencia internacional contra el cancer con mas de 800 estudios cruzados y los resultados no dejan lugar a dudas:

Está probado que carne procesada produce cancer, más concretamente cancer de colon, recto, páncreas y próstata.

Y comer carnes rojas, también puede producir los mismos efectos.

Pero aclaremos las cosas:


  1. ¿Qué son las carnes rojas?
    Las carnes rojas son todas las carnes de origen animal provenientes de mamíferos, como ternera, cerdo, cordero, y carnes de caza. Se las denomina carnes rojas porque es su color antes de ser cocinadas. Son un alimento muy importante, porque contienen gran cantidad de proteínas, hierro, vitamina B y zinc.
  2. ¿Qué son las carnes procesadas?
    Las carnes procesadas son todas aquellas que han sido modificadas, cocinadas o conservadas para modificar sus propiedades, como su sabor, o evitar su degradación:«carne que ha sido transformada por la salazón, el endurecimiento, la fermentación, el ahumado, u otros procesos para realzar su sabor o mejorar su conservación. Las carnes más procesadas contienen cerdo o vacuno, pero las carnes procesadas pueden también contener otras carnes rojas, la carne de ave, de vísceras o de sub-productos tales como la sangre». Los perritos calientes (salchichas de Frankfurt), el jamón, las salchichas, el corned-beef, el biltong o la carne de vacuno secada o todavía las conservas de carne (patés...) y diversas preparaciones a base de carne y carnes en salsas son ejemplos de «carne procesada».
  3. ¿Cómo están seguros de que producen cancer?
    El informe es como un recopilatorio, contiene los resultados de muchas pruebas, con mas de 800 estudios en 15 tipos diferentes de carnes y carnes procesadas, con animales y con humanos, y todos llegan a la misma conclusión, que comer carnes rojas o procesadas da cancer.
    La diferencia entre unas y otras es que en el caso de las carnes procesadas ha quedado sobradamente probado su efecto, y en el de las carnes rojas aunque también esta probado que producen cancer, hay menos datos para su análisis.
  4. ¿Pero cuál es el porcentaje exacto de padecer cancer si las como?
    Realmente no se puede saber, porque en el estudio se analizan muchas carnes juntas, pero por ejemplo, con 50 gramos al día de carnes procesadas se dice que aumenta el riesgo de padecer cancer de colon en un 18%, si en España la media es un 7%, esto supone un 1,5% más, con lo que pasarías a tener un 8,5% de probabilidades de sufrir cancer a lo largo de tu vida (parece poco pero mejor reducir que aumentar). Ahora bien, si la media de consumo de estas carnes en España son 12 Kg/año por persona, eso nos deja que lo que suele comer la gente es alrededor de 30 gramos al día, una cantidad mucho menor. (en otros países como USA las cifras se disparan)
Image result for carnes rojas 

Ahora tengamos en cuenta la repercusión de esta noticia, ya que la amplia mayoría de la población mundial consume carne roja o procesada y hasta ahora estaba recomendado su consumo en bajas cantidades (como 1 o 2 veces a la semana).

Todas las grandes multinacionales del sector alimentación o cadenas de comida rápida dependen de las carnes rojas o procesadas.

Es más, el volumen de los animales del planeta equivale a 2 tercios de animales de granja y un tercio todos los demás animales del mundo (elefantes, ballenas, rinocerontes, hormigas...). Y sólo el la masa de las cabezas de ganado vacuno suponen mas de la mitad del peso total de todos los animales del planeta.

Hay muchos intereses en que este estudio no salga a luz, ya que sus consecuencias son enormes, tanto para el sector cárnico como para la salud de las personas.

Es una pena que den cancer, con lo rican que están. Habrá que busca otras alternativas a estos alimentos, y mientras reducir su consumo a unos mínimos saludables.
 
Image result for carnes rojasImage result for carnes rojas

Os dejo con el estudio:




Fuentes:

Red Meat and Processed Meat

IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 114
.
Lyon (FR): International Agency for Research on Cancer.
ISBN-13: 978-9283201526 (paperback)ISBN-13: 978-9283201809 (pdf)ISBN-13: 978-9283213376 (epub)
This volume of the IARC Monographs provides evaluations of the consumption of red meat and the consumption of processed meat.
Red meat refers to unprocessed mammalian muscle meat (e.g. beef, veal, pork, lamb) including that which may be minced or frozen. Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking or other processes to enhance flavour or improve preservation. Most processed meats contain pork or beef, but may also contain other meats including poultry and offal (e.g. liver) or meat by-products such as blood.
Red meat contains proteins of high biological value, and important micronutrients such as B vitamins, iron (both free iron and haem iron), and zinc.
Carcinogens, including heterocyclic aromatic amines and polycyclic aromatic hydrocarbons, can be produced by cooking of meat, with greatest amounts generated at high temperatures by pan-frying, grilling, or barbecuing. Meat processing such as curing and smoking can result in formation of carcinogenic chemicals including N-nitroso compounds and polycyclic aromatic hydrocarbons.
An IARC Monographs Working Group reviewed epidemiological evidence, animal bioassays, and mechanistic and other relevant data to reach conclusions as to the carcinogenic hazard to humans of the consumption of red meat and processed meat. The Working Group assessed more than 800 epidemiological studies that investigated the association of cancer (more than 15 types) with consumption of red meat or processed meat, including large cohorts in many countries, from several continents, with diverse ethnicities and diets.

Contents

This publication represents the views and expert opinions of an IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, which met in Lyon, 6–13 October 2015
Lyon, France - 2018

IARC MONOGRAPHS

In 1969, the International Agency for Research on Cancer (IARC) initiated a programme on the evaluation of the carcinogenic risk of chemicals to humans involving the production of critically evaluated monographs on individual chemicals. The programme was subsequently expanded to include evaluations of carcinogenic risks associated with exposures to complex mixtures, lifestyle factors and biological and physical agents, as well as those in specific occupations. The objective of the programme is to elaborate and publish in the form of monographs critical reviews of data on carcinogenicity for agents to which humans are known to be exposed and on specific exposure situations; to evaluate these data in terms of human risk with the help of international working groups of experts in carcinogenesis and related fields; and to indicate where additional research efforts are needed. The lists of IARC evaluations are regularly updated and are available on the Internet at http://monographs.iarc.fr/.
This programme has been supported since 1982 by Cooperative Agreement U01 CA33193 with the United States National Cancer Institute, Department of Health and Human Services. Additional support has been provided since 1986 by the European Commission Directorate-General for Employment, Social Affairs, and Inclusion, initially by the Unit of Health, Safety and Hygiene at Work, and since 2014 by the European Union Programme for Employment and Social Innovation “EaSI” (2014–2020) (for further information please consult: http://ec.europa.eu/social/easi). Support has also been provided since 1992 by the United States National Institute of Environmental Health Sciences, Department of Health and Human Services. The contents of this volume are solely the responsibility of the Working Group and do not necessarily represent the official views of the United States National Cancer Institute, the United States National Institute of Environmental Health Sciences, the United States Department of Health and Human Services, or the European Commission.
Image 978-9283201809-C001-F001.jpg
Co-funded by the European Union
  • Published by the International Agency for Research on Cancer, 150 cours Albert Thomas, 69372 Lyon Cedex 08, France
  • ©International Agency for Research on Cancer, 2018
  • On-line publication, March 2018
  • Distributed by WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
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The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city, or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.
The IARC Monographs Working Group alone is responsible for the views expressed in this publication.

IARC Library Cataloguing in Publication Data

Red meat and processed meat / IARC Working Group on the Evaluation of Carcinogenic Risks to Humans (2015: Lyon, France)
(IARC monographs on the evaluation of carcinogenic risks to humans ; volume 114).
1. Carcinogens 2. Red Meat – adverse effects 3. Food Additives – adverse effects 4. Diet, Western – adverse effects 5. Risk Factors
I. International Agency for Research on Cancer II. Series
ISBN 978 92 832 0180 9 (NLM Classification: W1)
ISSN 1017-1606
Cover image: © iStockphoto.com/Giorez
© International Agency for Research on Cancer, 2018. For more information contact publications@iarc.fr.