If they want natural urea rather than the synthetic kind, let them have it.
Is the urea in animal waste different from the urea that comes from a retort?
Nitrogen compounds, like urea, a big component of urine, are transformed over several steps.
This gene is the blueprint for an enzyme called urease, which converts urea into ammonium ions.
Otherwise, it's probably best to move with the times and deal with the occasional urea fluid fill-ups.
As the oxygen level fell, though, something else rose: the level of urea.
Urea injection, which helps catalytic converters clean up the exhaust of diesel engines, sounds like a pain in the neck.
The Jetta TDI SportWagen could be a spiffy urea-free replacement for the old Benz wagon if you don't mind something smaller.
Some vehicles still don't need urea it to meet tighter emissions standards.
The day after the budget the government had to reduce increases in the price of petrol and urea (used for making fertiliser), because of growing oposition within its ranks.
Also, to comply with prevailing U.S. emissions standards on nitrogen oxides, or NOx, these big diesels require fairly complicated systems of postcombustion treatment with a water-based urea solution, called AdBlue.
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One way round this for a swimming animal is to develop an outlet which allows urea to dissolve directly in the water as it swims, which is what the turtles seem to have done.
The Jetta TDI has a 2.0-liter four-cylinder turbodiesel engine that operates efficiently enough not to require the new urea-injection technology that many larger, heavier diesels do in order to comply with exhaust emissions standards.
In Europe the trucking industry has settled on a technology called selective catalytic reduction, in which urea is periodically injected into the exhaust system to break down the NOx, converting nitrogen oxides into (somewhat) harmless ammonia.
Dr Ip looked at which genes were active in the gill-like structures of the mouth and found one that appears, from its similarity to genes of known function from other species, to encode a urea transporter.
But he said that the government would need to control expenses, especially on subsidies such as diesel and fertilizers - mainly non-urea, and expand the tax base to generate more revenue to be able to meet fiscal objectives over the long run.
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In a 2011 ruling, Duffy wrote that while Yousef was awaiting trial, he had been trying to collect urea -- a component of urine -- and a type of watch that had been used in a detonator in the airline bomb plot.
Indeed, a calculation Dr Ip performed, based on the volume and composition of the urine he collected in the plastic buckets, and of the head-dunking water at the end of each day, suggested that only 6% of the urea excreted by the turtles was leaving them in the traditional manner, via urine.
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