Note 11 - Income Taxes (Tables)

12 Months Ended

Jun. 30, 2022

Notes Tables

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	As of June 30,
	2022			2021
Fixed assets	$	9		$	55
Share-based compensation		525			563
Other accruals		106			49
Asset retirement obligation		134			128
Research credit carryforwards		389			277
Other		7			6
Net operating loss carryforwards		17,904			16,568
Total deferred tax assets		19,074			17,646
Valuation allowance		(19,074	)		(17,646	)
Total	$	-		$	-

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	For the year ended June 30,
	2022			2021			2020
U.S. federal statutory income tax rate		21	%		21	%		21	%
Expected income tax benefit	$	(1,522	)	$	(711	)	$	(724	)
Meals and entertainment		14			6			8
Non-deductible penalties		25			22			24
Change in estimate		(9	)		28			(58	)
Incentive stock options		126			48			-
Research credit		(62	)		(52	)		11
Change in valuation allowance		1,428			659			739
Income tax expense (benefit)	$	-		$	-		$	-