Dennis Nagle was appointed vice president, manufacturing, at Altair Nanotechnolgies, a Reno, Nev., maker of ceramic nanomaterial products. Nagle was operations manager at Atotech USA Inc., a supplier to the printed circuit board manufacturing industry. Previously, he held senior positions at Zeeland Chemicals and at Nanophase Technologies.    . . .    . . .    JP Sercel Associates, of Hollis, N.H., has appointed Terry Jeglum and Electronic Technology Corp. (ETC) of St. Charles, Ill., to represent its line of ultraviolet (UV) laser processing systems and job shop services in Illinois, Indiana and Wisconsin. JPSA makes UV excimer and DPSS laser micro machining and UV and vacuum-UV laser beam delivery systems and performs UV laser materials processing development, optical damage testing and excimer laser refurbishment services.    . . .    Lumenis Ltd., an Israel-based developer of laser and light devices for medical, aesthetic, ophthalmic, dental and veterinary applications, said it is expanding the dental segment of its medical laser business and has restructured its sales and marketing efforts based on expected growth in the dental market. The company has established a direct sales force and sales management team as part of its existing Americas' sales management organization. It previously used independent representatives for most of its sales.