MIT Professor Emeritus Bernhardt Wuensch ’55, SM ’57, PhD ’63, a crystallographer and beloved teacher whose warmth and dedication to ensuring his students mastered the complexities of a precise science matched the analytical rigor he applied to the study of crystals, died this month in Concord, Massachusetts. He was 90. Remembered fondly for his fastidious attention to detail and his office stuffed with potted orchids and towers of papers, Wuensch was an expert in X-ray crystallography, which involves shooting X-ray beams at crystalline materials to determine their underlying structure. He…