A computational procedure is presented for investigating photoinduced switchable rotaxanes and demonstrated for a known system. This procedure starts with the generation of >10 4 chemically reasonable rotaxane coconformations based on an empirical intramolecular potential-energy function. Each of the structures is then assigned by its gross structural features (coiled or extended) and by the position of the ring along the shaft. Single-point energy calculations at the semiempirical (AM1) level are then carried out for each structure in the singlet (ground), triplet, and anionic doublet states. The structural features are then correlated with energy for each state. What emerges is a profile of the structure-energy relationship that captures the salient features of the system that endow it with devicelike character. The full geometry optimization of a subset of the coconformations demonstrates that the procedure based on single-point calculations is sufficient to obtain a profile of the relationship of the structural features to energy that is consistent with experiments at a greatly reduced computational cost.

Co-conformational selectivity and structure-energy relationships in a [3]rotaxane are investigated with a recently developed multiple-sampling and statistical analysis procedure for modeling interlocked molecules and mechanical molecular devices. The results presented confirm the experimentally observed co-conformational selectivity. The theoretical calculations reveal that ring-ring interactions are very small and ring-shaft inter-component interactions decide the co-conformational preference. In particular, it is found that stronger ring binding at the central binding station on the shaft than at either of the two terminal binding stations gives rise to the observed co-conformational preference. Analysis of radius of gyration data shows that co-conformational isomerism is not strongly correlated to coiling of the shaft.

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The vibrational dynamics of nanosystem components are likely to play a critical role in both nanomechanical and nanoelectronic systems. We demonstrate that vibrational analysis with a lumped-inertia technique can efficiently and reliably anticipate certain vibrational properties without the need for performing costly comprehensive full normal-mode computations. Three classes of linear oligomers with potential for application in nanoelectronics are investigated with this technique. The torsional-twisting frequencies from the lumpedinertia model accurately reproduce the frequencies computed with full normal-mode analysis based on electronic structure calculations. The lumped-inertia model reveals the importance of long-range coupling in torsionaltwisting dynamics and affords a partitioning of the effect of phenyl ring substituents on the torsional vibrational frequencies between inertial and electronic structure contributions.

Purpose Additive manufacturing (AM) is an innovative printing technology that can manufacture 3-dimensional solid objects by adding layers of material from model data. AM in oral and maxillofacial surgery (OMFS) provides several clinical applications such as surgical guides and implants. However, the adoption of AM in OMFS is not well covered. The purpose was to study the adoption of AM in OMFS in university and non-university hospitals in Sweden. Three research questions were addressed: What is the degree of using AM solutions in university and non-university hospitals?; What are AM solutions used?; How are the AM solutions accessed (production mode) in university hospitals and non-university hospitals? Methods A survey was distributed to OMF surgeons in Sweden. The questionnaire consisted of 16 questions. Data were analyzed through descriptive and content analysis. Results A total of 14 university and non-university hospitals were captured. All 14 hospitals have adopted AM technology and 11 of the hospitals adopted AM in OMFS. Orthognathic and trauma surgery are two major types of surgery that involve AM technology where material extrusion and vat polymerization are the two most used AM technologies in OMFS. The primary application of AM was in medical models and guides. Conclusion Majority of Swedish university hospitals and non-university hospitals have adopted AM in OMFS. The type of hospital (university or non-university hospital) has no impact on AM adoption. AM in OMFS in Sweden can be perceived to be a mature clinical application.