Ceramic Fuel Cells fell after announcing the resignation of two of its senior bosses.The company, which makes generators that use fuel cell technology to convert natural gas into electricity and heat, said managing director John Dempsey had left the firm on 31st December.The business also confirmed that Chief Executive Brendan Dow had stepped down on the same date.The announcements gave no further details of the circumstances of the resignations.However, when Dow's resignation was revealed in October, the firm put it down to "significant changes as it moves the focus of its operations to Europe".Ceramic's shares were down 3% at 1530 on Wednesday following the announcement.