Reconciliation of income taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of income taxes
Tax at statutory rate of 25%	$ (6,511,844)	$ (4,736,660)
Current and prior years		8,534
Effect of tax holiday	2,563,701	1,834,517
Other, primarily the effect of US tax rates	7,815	0
Change in valuation allowance Reconciliation	4,017,370	3,955,022
Income tax expense Reconciliation	$ 77,042	$ 1,061,413