ChemTS: An Efficient Python Library for de novo Molecular Generation

Automatic design of organic materials requires black-box optimization in a vast chemical space. In conventional molecular design algorithms, a molecule is built as a combination of predetermined fragments. Recently, deep neural network models such as variational auto encoders (VAEs) and recurrent neural networks (RNNs) are shown to be effective in de novo design of molecules without any predetermined fragments. This paper presents a novel python library ChemTS that explores the chemical space by combining Monte Carlo tree search (MCTS) and an RNN. In a benchmarking problem of optimizing the octanol-water partition coefficient and synthesizability, our algorithm showed superior efficiency in finding high-scoring molecules. ChemTS is available at https://github.com/tsudalab/ChemTS

A Workability and sustainability assessment of multistorey earthquake-resistant timber building

Although two-Thirds of the area of Japan is covered with forests, the domestic wood resources are not widely used in the construction sector. Due to the complex design process, construction work and high precision needed, most of timber constructions are limited to one or two-storey buildings. This paper aims to clarify the efficiency of a proposed joint system for CLT walls-steel beams hybrid structure. In addition, the workability and the environmental impact of the proposed hybrid system in comparison to other structures were analysed. The proposed joint system showed higher workability and efficiency compared to other conventional joints in Japan. The construction process of a prototype of a module with the proposed system was studied and confirmed its easier and faster work than the conventional system. A 4-storey building was taken as a case study to evaluate the environmental impact of the proposed system. Although the proposed hybrid system showed higher carbon emissions than a conventional CLT alternative, advantage in terms of the environmental impact was confirmed in comparison to a reinforced concrete and a steel structure

DEVELOPMENT OF A NOVEL JOINT SYSTEM FOR MID-TO-HIGHRISE CLT WALL BUILDINGS IN SEISMIC REGIONS

In Japan, the possibility of multi-story timber buildings is not yet practiced at a large scale due to the complex structural design process and construction cost. In conventional CLT buildings in Japan, a high number of complex steel connections are required. In this practice, complex processing of CLTs panel is also required. The objective of this paper is to propose easy-to-apply and easy-to-design steel joints. The proposed joint is designed to resist both shear and tensile forces to reduce complex steel parts. Single-bolt element tension tests were conducted to investigate the effect of the fibre direction, bolt diameter, and bolt embedded length. Cyclic loading for single and coupled CLT walls with the proposed joints was also conducted. The failure characteristics and strength of single-bolt connections could be predicted by the ratio of bolt embedded length and diameter. The fibre direction was found to have a minor effect on the connection strength. The proposed joint system showed high strength and ductility as found by the cyclic loading. The lateral strength of a wall with two panels was double the single wall case, indicating the lack of interaction between the two panels

De novo creation of a naked eye–detectable fluorescent molecule based on quantum chemical computation and machine learning

Designing fluorescent molecules requires considering multiple interrelated molecular properties, as opposed to properties that straightforwardly correlated with molecular structure, such as light absorption of molecules. In this study, we have used a de novo molecule generator (DNMG) coupled with quantum chemical computation (QC) to develop fluorescent molecules, which are garnering significant attention in various disciplines. Using massive parallel computation (1024 cores, 5 days), the DNMG has produced 3643 candidate molecules. We have selected an unreported molecule and seven reported molecules and synthesized them. Photoluminescence spectrum measurements demonstrated that the DNMG can successfully design fluorescent molecules with 75% accuracy (n = 6/8) and create an unreported molecule that emits fluorescence detectable by the naked eye