Derivative Liabilities (Tables)

3 Months Ended

12 Months Ended

Jan. 31, 2014

Jul. 31, 2013

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	(2,039,599)	(70,732,022)
Additional warrants issued in January 2014 financing	942,279	26,666,668
Increase in fair value of derivative warrant liability	1,122,959	n/a
Balance at January 31, 2014 – Derivative warrant liability	$  5,259,929	176,622,183

The following summarizes the changes in the value of the derivative warrant liability from August 1, 2011 until July 31, 2013:

	Value	No. of Warrants
Balance at August 1, 2011 – Derivative warrant liability	$   8,745,508	80,234,017
Exercise of warrants classified as derivative liability	(7,230,734)	(49,863,260)
Additional warrants issued in February 2012 financing	1,811,746	13,333,333
Additional warrants from price protection features of existing warrants	1,548,813	11,444,440
Decrease in fair value of derivative warrant liability	(793,706)	n/a
Balance at July 31, 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

Fair Value Assumptions Used in Accounting for Derivative Warrant Liability

	January 31, 2014			July 31, 2013
Current exercise price	$	0.03		$	0.03
Time to expiration		3.2 years			3.5 years
Risk-free interest rate		0.69	%		0.49	%
Estimated volatility		86	%		85	%
Dividend		-0-			-0-
Stock price at period end date	$	0.03		$	0.035

The key inputs used in the July 31, 2013 and July 31, 2012 fair value calculations were as follows:

	July 31, 2013			July 31, 2012
Current exercise price	$	0.03		$	0.15
Time to expiration		3.5 years			3.9 years
Risk-free interest rate		0.49	%		0.45	%
Estimated volatility		85	%		104	%
Dividend		-0-			-0-
Stock price at period end date	$	0.035		$	0.093

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

	January 31, 2014			July 31, 2013
Underlying number of units of convertible preferred stock		425			1,225
Underlying number of units of warrants		14,166,667			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		0.38 years			0.88 years
Risk-free interest rate		0.06	%		0.11	%
Estimated volatility		67	%		114	%
Dividend		-0-			-0-
Stock price at period end date	$	0.042		$	0.035

The key inputs used in the fair value calculation at July 31, 2013 were as follows:

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