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40 The PCB Design Magazine • July 2016 Conclusion Design engineers can create constraints and plan out bus routing. PCB Designers can quickly screen a design for both physical and electrical rule violations. And signal and power integrity engineers can run detailed simulations that they can count on as being highly accurate. While this may not sound like a new concept, there is now integration of analysis technology in the design environment that enables all members of the team to use the same underlying analy- sis capabilities with varying levels of detail and expertise. Utilizing common libraries, common con- straints, and common analysis engines makes for a unique and highly communicative envi- ronment. No more silos! By enabling all mem- bers of the PCB design team to have a role in the electrical integrity of the design, fewer prob- lems are found in the lab and fewer design itera- tions are required. This results in meeting time to market requirements and having a predict- able schedule. PCBDESIGN Dennis Nagle is a product engineering architect at Cadence Design Systems. Researchers at the University of Liverpool are part of an interna- tional team that have shown a new way to op- erate a single molecular switch based on mecha- nochemistry. In a study published in Nature Chemistry, the team which includ- ed Fritz-Haber Institute of the Max Planck So- ciety (FHI-MPG), Berlin, Donostia International Physics Center, San Sebas- tian and the Polish Academy of Sciences, showed how hydrogen atoms in a single organic molecule adsorbed on a surface can be switched in a con- trolled manner on a sub-molecular scale by the force from an atomically sharp, metallic tip. This so-called tautomerization of hydrogen at- oms is an important reaction in organic chemistry and molecular biology and is also a promising pro- cess for realizing single-molecule switches in mo- lecular device applications. In addition, by using chemically modified tips, this tip-induced process also provides a new strat- egy to gain a deeper atomistic insight into catalyt- ic reactions and a new control of single-molecule chemistry. Liverpool Chemist Professor Mats Persson said: "This research is a new finding in the field of mechanochemistry and has implications for the development of fu- ture nanotechnologies in particular molecular devices such as switch- es for molecular elec- tronics." Takashi Kumagai at FHI-MPG, who initiated the study, wanted to explore the question of how much force is needed to operate a single-mole- cule switch. To address this, the researchers at- tached an organic molecule that exhibits tautom- erization to a surface and approached the tip of a combined atomic force and scanning tunneling microscope within a few atomic distances above the molecule. The research team also carried out extensive computer simulations in order to elucidate the atomistic mechanisms behind the force-induced tautomerization. Their calculations revealed that the tautomerization occurred by a reduction of its energy barrier upon approach of a metallic tip, while it could not be induced by a tip terminated by a Xe atom due to its inertness and softness. Chemists Show New Way to Operate a Single Molecular Switch SIGNAL INTEGRITY TOOLS AND DESIGN METHODOLOGY IN THE MODERN AGE