A three-dimensional tissue model of the human gut has been developed that will aid in
the study of gastrointestinal diseases.
Until now, scientists have had to rely on two-dimensional cultures or live animal
models, but the novel 3D hydrogel scaffold method will offer more realistic
physiological conditions.
The researchers are particularly interested how gut bacteria can be used to induce
intestinal cells to behave like insulin-producing beta cells — a project that could
result in a simple oral treatment of type 1 diabetes.
’We knew the flat models weren’t accurate. Cells behave differently in different 3D
environments …this will enable us to better study drug absorptions and interactions
between epithelia and bacteria in the intestine,’ said project lead Prof John March of
the Department of Biological and Environmental Engineering at Cornell University in the
US.
The team created a hard plastic mould, then covered it with a softer, so-called
sacrificial mould, made from calcium alginate that could be dissolved, leaving a
collagen scaffold upon which live cells could be grown.
The researchers tested the model by seeding it with human colon cells. After being
cultured for three weeks, it was covered with fingerlike structures mimicking the
intestinal villi, the threadlike projections covering the surface of the mucous
membrane in the small intestine where fluids and nutrients are absorbed.
In this way, they avoided damaging the delicate shapes during separation of the moulds.
Scientists had previously managed to fabricate models as small as 1 or 2 microns, but
slightly larger sizes have eluded them.
The artificial gut March and team created is around 1mm high and 200 microns across,
and is easily visible under a scanning electron microscope. They are in the process of
acquiring patents for the technology, which could be used in other areas of biomedical
research, such as tissue engineering, pharmaceutical sciences and cell biology.
2011年2月28日星期一
2011年2月22日星期二
Plastics bring functionality to household products
Plastics have long since secured a place in European kitchens and homes. However,
designers continue to push the limits of plastics’ versatility and durability to
produce highly desirable products that deliver both pleasing aesthetics and outstanding
functionality.
German housewares maker Koziol introduced its Kasimir cheese grater at the Maison &
Objet fair in October last year. Produced as a single part injection moulding in
transparent styrene acrylonitrile (SAN) polymer, the hedgehog-like device is available
in four transparent colours and in a clear version.
The grater measures 100mm by 156mm by 66 mm and is priced at less than €9. Koziol says
the quills on the back of the product, which double up as the grater blades, are tough
enough to handle even hard cheeses Parmigiano.
Kasimir has already picked up a German Pro-K consumer plastics products association
award for the Koziol design team and will be one of the featured products on the
association’s stand at the Ambiente trade show in Frankfurt this month.
Born in Sweden’s display at Maison & Objet included a number of plastics items
developed by French designer Pascal Charmolu. The newest of the products on display was
a combined bootjack and shoehorn in red, black, green or white polycarbonate. The 390mm
by 90mm product is intended to be hung on the wall when not in use.
Other exhibits included a sleek mailbox manufactured in glass fibre reinforced plastic
(GRP) and offered in a choice of 10 high gloss coloured finishes. This stylish design
picked up one of the 29 Design Plus awards at Ambiente 2009 and was nominated for the
2010 design prize of the Federal Republic of Germany.
The company also showed Charmolu’s ergonomic polypropylene 7.5-litre watering can and
a window-mountable bird feeder, the latter made in UV-resistant SAN and rubber.
Teerachai Suppameteekuiwat chose ethylene vinyl acetate (EVA) for Qualy’s Autumn
Leaves wedge-shaped maple-leaf shape door stops, which measure 147mm by 183mm and are
up to 38mm thick.
Meanwhile, through-coloured rotational moulded UV-resistant HDPE is used for the Ublo
garden chair collection, designed by Cedric Ragot for Qui est Paul. The same material
and process is also used for Ragot’s Kenny barstool, also produced for Qui est Paul,
which the company describes as “origami in plastic”.
While very much a household product, the double-heart baking mould thermoformed in
liquid crystal polymer (LCP) by Klaus Kunststofftechnik of Memmingen, Germany, picked
up an innovation award in the German TecPart competition (other winners are detailed on
page 26-27)
The mould is manufactured using a modified thermoforming process and a new Ticona
thermoformable Trex 541 40% mineral-filled grade of Vectra LCP. It withstands long-term
exposure to temperatures of up to 250°C, while offering advantages over metal of
ductility, design freedom and low thermal conductivity. Thermal conductivity is said to
be so low that the tray can be removed from the oven without gloves.
According to Ticona, this new LCP grade provides high melt strength and three times
higher melt viscosity than other 40% mineral filled LCP grades, making it suitable for
processing by sheet extrusion and thermoforming.
designers continue to push the limits of plastics’ versatility and durability to
produce highly desirable products that deliver both pleasing aesthetics and outstanding
functionality.
German housewares maker Koziol introduced its Kasimir cheese grater at the Maison &
Objet fair in October last year. Produced as a single part injection moulding in
transparent styrene acrylonitrile (SAN) polymer, the hedgehog-like device is available
in four transparent colours and in a clear version.
The grater measures 100mm by 156mm by 66 mm and is priced at less than €9. Koziol says
the quills on the back of the product, which double up as the grater blades, are tough
enough to handle even hard cheeses Parmigiano.
Kasimir has already picked up a German Pro-K consumer plastics products association
award for the Koziol design team and will be one of the featured products on the
association’s stand at the Ambiente trade show in Frankfurt this month.
Born in Sweden’s display at Maison & Objet included a number of plastics items
developed by French designer Pascal Charmolu. The newest of the products on display was
a combined bootjack and shoehorn in red, black, green or white polycarbonate. The 390mm
by 90mm product is intended to be hung on the wall when not in use.
Other exhibits included a sleek mailbox manufactured in glass fibre reinforced plastic
(GRP) and offered in a choice of 10 high gloss coloured finishes. This stylish design
picked up one of the 29 Design Plus awards at Ambiente 2009 and was nominated for the
2010 design prize of the Federal Republic of Germany.
The company also showed Charmolu’s ergonomic polypropylene 7.5-litre watering can and
a window-mountable bird feeder, the latter made in UV-resistant SAN and rubber.
Teerachai Suppameteekuiwat chose ethylene vinyl acetate (EVA) for Qualy’s Autumn
Leaves wedge-shaped maple-leaf shape door stops, which measure 147mm by 183mm and are
up to 38mm thick.
Meanwhile, through-coloured rotational moulded UV-resistant HDPE is used for the Ublo
garden chair collection, designed by Cedric Ragot for Qui est Paul. The same material
and process is also used for Ragot’s Kenny barstool, also produced for Qui est Paul,
which the company describes as “origami in plastic”.
While very much a household product, the double-heart baking mould thermoformed in
liquid crystal polymer (LCP) by Klaus Kunststofftechnik of Memmingen, Germany, picked
up an innovation award in the German TecPart competition (other winners are detailed on
page 26-27)
The mould is manufactured using a modified thermoforming process and a new Ticona
thermoformable Trex 541 40% mineral-filled grade of Vectra LCP. It withstands long-term
exposure to temperatures of up to 250°C, while offering advantages over metal of
ductility, design freedom and low thermal conductivity. Thermal conductivity is said to
be so low that the tray can be removed from the oven without gloves.
According to Ticona, this new LCP grade provides high melt strength and three times
higher melt viscosity than other 40% mineral filled LCP grades, making it suitable for
processing by sheet extrusion and thermoforming.
2011年2月21日星期一
Why you need to use your 'environmentally friendly' cotton carrier bag 131 times to be green
Cotton bags offered by many supermarkets may be less 'green' than plastic carriers - and may cause more global warming, according to scientists.
As a greater amount of energy goes into making a cloth carrier than a polythene one, a cotton bag has to be used 131 times before it has the same environmental impact than its plastic counterpart
And if a plastic bag is re-used as a bin liner, a cotton bag has to be used 173 times - nearly every day of the year - before its ecological impact is as low as a plastic bag on a host of factors including greenhouse gas emissions over its lifetime.
But most of us only use the bags around 51 times before they are thrown away, researchers found.
Paper bags - used by some clothes chains such as Primark - need to be used three times to fall below the environmental impact of the thin plastic carrier, while bags for life - made of stronger plastic - have to be used four times to start having less ecological impact.
The government sponsored research, 'Life Cycle Assessment of Supermarket Carrier Bags' by Dr Chris Edwards and Jonna Meyhoff Fry looked at the environmental impact of six different types of bags.
Although completed in 2008, it has not yet been published, with plastic bag makers claiming the findings have been suppressed - although the Environment Agency said it is awaiting 'peer review' - checks by other scientists.
Using a thin plastic bag equates to generating 1.57kg of carbon dioxide. A cotton bag would have to be re-used 171 times to emit the same level of CO2
Using a thin plastic bag equates to generating 1.57kg of carbon dioxide. A cotton bag would have to be re-used 171 times to emit the same level of CO2
Using a thin plastic bag - made from a plastic called high-density polyethylene (HDPE) - equates to generating 1.57kg of carbon dioxide, the greenhouse gas that scientist believe leads to global warming according to the report. A cotton bag would have to be re-used 171 times to emit the same level of CO2.
Cotton bags typically made in China have a greater environmental impact because of the water and fertiliser required in their production, as well as their transportation and greater weight.
The researchers concluded: 'The HDPE bag had the lowest environmental impacts of the single use options in nine of the 10 impact categories. The bag performed well because it was the lightest single use bag considered.'
Plastic bags have also come under fire for using up oil and for littering the countryside and fouling the marine environment for wildlife.
A study into the impact of different bags was finished in 2008 but has not yet been published
A study into the impact of different bags was finished in 2008 but has not yet been published
However, the research found that biodegradable bags made of starch were not a greener option than HDPE bags as they are less environmentally friendly to make and heavier.
The authors write: 'In practical terms of global warming potential, eutrophication [a form of river pollution] ozone layer depletion, toxicity and ecotoxicity the current starch polyester blend bag is significantly worse than conventional single-use options due to the high impact of raw material production on those categories.'
The Daily Mail, through its 'Banish the Bags' campaign has spearheaded efforts to avoid using plastic bags wherever possible to save the environment and the public are reducing their use of plastic bags.
Figures from WRAP, the government's Waste and Resources Action Program, show a total decline in all types of carrier bags issued to 4.5 billion (41%) over the years 2006-2010 – effectively saving 39,700 tonnes of material from entering the waste stream
Peter Woodall, speaking on behalf of the Packaging and Films Association, which represents plastic bag makers, said: 'This analysis shows what we have been saying for years. Plastic bags are a more environmentally friendly option than cotton bags.
'It comes down to reducing, reusing and recycling.' He also cited Canadian research that cotton bags can harbour can harbour germs and mould which can be harmful to health - unless they are washed.
An Environment Agency spokesperson said: 'The report focuses on the greenhouse gas emissions of manufacturing different types of carrier bags.
'Much of the environmental impact of these bags is associated with the primary resource use and production.
'The final report due to be published in the next two weeks, will show that all multi-use bags - plastic, cotton or paper - need to be reused on multiple occasions to justify the additional carbon footprint of their production.
As a greater amount of energy goes into making a cloth carrier than a polythene one, a cotton bag has to be used 131 times before it has the same environmental impact than its plastic counterpart
And if a plastic bag is re-used as a bin liner, a cotton bag has to be used 173 times - nearly every day of the year - before its ecological impact is as low as a plastic bag on a host of factors including greenhouse gas emissions over its lifetime.
But most of us only use the bags around 51 times before they are thrown away, researchers found.
Paper bags - used by some clothes chains such as Primark - need to be used three times to fall below the environmental impact of the thin plastic carrier, while bags for life - made of stronger plastic - have to be used four times to start having less ecological impact.
The government sponsored research, 'Life Cycle Assessment of Supermarket Carrier Bags' by Dr Chris Edwards and Jonna Meyhoff Fry looked at the environmental impact of six different types of bags.
Although completed in 2008, it has not yet been published, with plastic bag makers claiming the findings have been suppressed - although the Environment Agency said it is awaiting 'peer review' - checks by other scientists.
Using a thin plastic bag equates to generating 1.57kg of carbon dioxide. A cotton bag would have to be re-used 171 times to emit the same level of CO2
Using a thin plastic bag equates to generating 1.57kg of carbon dioxide. A cotton bag would have to be re-used 171 times to emit the same level of CO2
Using a thin plastic bag - made from a plastic called high-density polyethylene (HDPE) - equates to generating 1.57kg of carbon dioxide, the greenhouse gas that scientist believe leads to global warming according to the report. A cotton bag would have to be re-used 171 times to emit the same level of CO2.
Cotton bags typically made in China have a greater environmental impact because of the water and fertiliser required in their production, as well as their transportation and greater weight.
The researchers concluded: 'The HDPE bag had the lowest environmental impacts of the single use options in nine of the 10 impact categories. The bag performed well because it was the lightest single use bag considered.'
Plastic bags have also come under fire for using up oil and for littering the countryside and fouling the marine environment for wildlife.
A study into the impact of different bags was finished in 2008 but has not yet been published
A study into the impact of different bags was finished in 2008 but has not yet been published
However, the research found that biodegradable bags made of starch were not a greener option than HDPE bags as they are less environmentally friendly to make and heavier.
The authors write: 'In practical terms of global warming potential, eutrophication [a form of river pollution] ozone layer depletion, toxicity and ecotoxicity the current starch polyester blend bag is significantly worse than conventional single-use options due to the high impact of raw material production on those categories.'
The Daily Mail, through its 'Banish the Bags' campaign has spearheaded efforts to avoid using plastic bags wherever possible to save the environment and the public are reducing their use of plastic bags.
Figures from WRAP, the government's Waste and Resources Action Program, show a total decline in all types of carrier bags issued to 4.5 billion (41%) over the years 2006-2010 – effectively saving 39,700 tonnes of material from entering the waste stream
Peter Woodall, speaking on behalf of the Packaging and Films Association, which represents plastic bag makers, said: 'This analysis shows what we have been saying for years. Plastic bags are a more environmentally friendly option than cotton bags.
'It comes down to reducing, reusing and recycling.' He also cited Canadian research that cotton bags can harbour can harbour germs and mould which can be harmful to health - unless they are washed.
An Environment Agency spokesperson said: 'The report focuses on the greenhouse gas emissions of manufacturing different types of carrier bags.
'Much of the environmental impact of these bags is associated with the primary resource use and production.
'The final report due to be published in the next two weeks, will show that all multi-use bags - plastic, cotton or paper - need to be reused on multiple occasions to justify the additional carbon footprint of their production.
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