Derivative Liabilities (Tables)

9 Months Ended

12 Months Ended

Apr. 30, 2015

Jul. 31, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Changes in value of derivative warrant liability

		Value		No. of Warrants
Balance at August 1, 2012 – Derivative warrant liability	$	4,081,627		55,148,530
Additional warrants issued in August 2012 financing		624,797		9,375,000
Additional warrants issued in December 2012 financing		762,355		24,999,999
Additional warrants issued in June 2013 financing		1,189,744		40,833,335
Additional warrants from price protection features of existing warrants		7,484,550		236,219,094
Exercise of warrants		(5,629,130	)	(145,888,421	)
Decrease in fair value of derivative warrant liability		(3,279,650	)	n/a
Balance at July 31, 2013 – Derivative warrant liability	$	5,234,293		220,687,537
Exercise of warrants		(2,194,496	)	(76,732,020	)
Additional warrants issued in January 2014 financing		942,279		26,666,668
Additional warrants issued in March 2014 financing		2,016,064		69,166,667
Decrease in fair value of derivative warrant liability		(3,362,497	)	n/a
Balance at July 31, 2014 – Derivative warrant liability	$	2,635,643		239,788,852

Fair Value Assumptions Used in Accounting for Derivative Warrant Liability

		April 30, 2015			July 31, 2014
Current exercise price	$	0.03		$	0.03
Time to expiration		2.6 years			3.3 years
Risk-free interest rate		0.91	%		1.02	%
Estimated volatility		79	%		80	%
Dividend		-0-			-0-
Stock price at period end date	$	0.0225		$	0.0210

		July 31, 2014			July 31, 2013
Current exercise price	$	0.03		$	0.03
Time to expiration		3.3 years			3.5 years
Risk-free interest rate		1.02	%		0.49	%
Estimated volatility		80	%		85	%
Dividend		-0-			-0-
Stock price at period end date	$	0.021		$	0.035

Fair Value Assumptions Used in Accounting for Derivative Additional Investment Rights Liability

		July 31, 2014
Underlying number of units of convertible preferred stock		2,075
Underlying number of units of warrants		69,166,667
Current exercise price of warrants	$	0.03
Current conversion price of preferred stock	$	0.03
Time to expiration		0.65 years
Risk-free interest rate		0.09	%
Estimated volatility		61	%
Dividend		-0-
Stock price at period end date	$	0.021

		July 31, 2014			July 31, 2013
Underlying number of units of convertible preferred stock		2,075			1,225
Underlying number of warrants		69,166,667			40,833,335
Current exercise price of warrants	$	0.03		$	0.03
Current conversion price of preferred stock	$	0.03		$	0.03
Time to expiration		0.65 years			0.88 years
Risk-free interest rate		0.09	%		0.11	%
Estimated volatility		61	%		114	%
Dividend		-0-			-0-
Stock price	$	0.021		$	0.035

Derivative warrant liability

		Value		No. of Warrants
Balance at August 1, 2013 – Derivative warrant liability	$	5,234,293		220,687,537
Exercise of warrants		(2,194,496	)	(76,732,020	)
Additional warrants issued in January 2014 financing		942,279		26,666,668
Additional warrants issued in March 2014 financing		2,016,064		69,166,667
Decrease in fair value of derivative warrant liability		(3,362,497	)	n/a
Balance at July 31, 2014 – Derivative warrant liability	$	2,635,643		239,788,852
Increase in fair value of derivative warrant liability		53,597		n/a
Balance at April 30, 2015 – Derivative warrant liability	$	2,689,240		239,788,852