The IUPAC International Chemical Identifier (InChI) is a structure-based chemical identifier that encodes various aspects of a chemical structure into a hierarchically layered line notation. Because InChI is non-proprietary, open-source, and freely available to everyone, it is adopted in popular chemical information resources and software programs. This paper describes the InChI Open Education Resource (OER) (https://www.inchi-trust.org/oer/), designed to provide educators and other interested parties with resources, training material, and information related to InChI. Currently, the OER contains over 100 materials collected from various sources and provides users with search, filtering, and sorting functionalities to locate specific records. New relevant materials can be suggested by anyone, allowing the scientific community to share and find InChI-related resources. This paper will show how to use the InChI OER tag taxonomy to filter content and demonstrate two resources within the InChI OER; the ChemNames2LCSS Google Sheet and the InChILayersExplorer, an Excel spreadsheet that breaks an InChI into its layers. While the InChI OER is of value to a broader chemistry community, this paper seeks to reach out to chemical educators and provide them with an understanding of InChI and its role in the practice of science.

The International Union of Pure and Applied Chemistry (IUPAC) has a long tradition of supporting the compilation of chemical data and their evaluation through direct projects, nomenclature and terminology work, and partnerships with international scientific bodies, government agencies and other organizations. The IUPAC Interdivisional Subcommittee on Critical Evaluation of Data (ISCED) has been established to provide guidance on issues related to the evaluation of chemical data. In this first report we define the general principles of the evaluation of scientific data and describe best practices and approaches to data evaluation in chemistry.

We present a sequence-to-sequence machine learning model for predicting the IUPAC name of a chemical from its standard International Chemical Identifier (InChI). The model uses two stacks of transformers in an encoder-decoder architecture, a setup similar to the neural networks used in state-of-the-art machine translation. Unlike neural machine translation, which usually tokenizes input and output into words or sub-words, our model processes the InChI and predicts the IUPAC name character by character. The model was trained on a dataset of 10 million InChI/IUPAC name pairs freely downloaded from the National Library of Medicine\'s online PubChem service. Training took seven days on a Tesla K80 GPU, and the model achieved a test set accuracy of 91%. The model performed particularly well on organics, with the exception of macrocycles, and was comparable to commercial IUPAC name generation software. The predictions were less accurate for inorganic and organometallic compounds. This can be explained by inherent limitations of standard InChI for representing inorganics, as well as low coverage in the training data.

Choosing the right mentors and role models has a profound impact in both our lives and professional careers; however, most often, not enough time or thought is given to this important decision. Because of that, we may miss some great opportunities and limit the potential benefits. In this invited contribution, I share my personal experience on nurturing the relationship with mentors and on choosing role models with my same values and a strong sense of service.

BACKGROUND: An inverted repeat is a DNA sequence followed downstream by its reverse complement, potentially with a gap in the centre. Inverted repeats are found in both prokaryotic and eukaryotic genomes and they have been linked with countless possible functions. Many international consortia provide a comprehensive description of common genetic variation making alternative sequence representations, such as IUPAC encoding, necessary for leveraging the full potential of such broad variation datasets.
RESULTS: We present IUPACPAL, an exact tool for efficient identification of inverted repeats in IUPAC-encoded DNA sequences allowing also for potential mismatches and gaps in the inverted repeats.
CONCLUSIONS: Within the parameters that were tested, our experimental results show that IUPACPAL compares favourably to a similar application packaged with EMBOSS. We show that IUPACPAL identifies many previously unidentified inverted repeats when compared with EMBOSS, and that this is also performed with orders of magnitude improved speed.

How many candles?! The year 2019 has been named as the International Year of the Periodic Table in accordance with Mendeleev\'s work from 1869. In line with other celebratory events and articles to be found this year in Chemistry-A European Journal, here, Eric R. Scerri provides an historical account of the development of the periodic table and some of the debates and considerations surrounding this fundamental elementary ensemble.

A new solid-state nuclear magnetic resonance (NMR) thermometry sample is proposed. The 207Pb NMR chemical shift of a lead halide perovskite, methylammonium lead chloride (MAPbCl3) is very sensitive to temperature, 0.905±0.010ppmK-1. The response to temperature is linear over a wide temperature range, from its tetragonal to cubic phase transition at 178K to >410K, making it an ideal standard for temperature calibrations in this range. Because the 207Pb NMR lineshape for MAPbCl3 appears symmetric, the sample is ideal for calibration of variable temperature NMR data acquired for spinning or non-spinning samples. A frequency-ratio method is proposed for referencing 207Pb chemical shifts, based on the 1H and 13C frequencies of the methylammonium cation, which are used asan internal standard. Finally, this new NMR thermometer has been used to measure the degree of frictional heating asa function of spinning frequency for a series of MAS rotors ranging in outer diameter from 1.3 to 7.0mm. As expected, the largest diameter rotors are more susceptible to frictional heating, but lower diameter rotors are subjected to higher frictional heating temperatures as they are typically spun at much higher spinning frequencies.

The symbols for the new IUPAC elements named in November 2016 can introduce subtle ambiguities within cheminformatics software. The ambiguities are described and demonstrated by highlighting inconsistencies between software when handling existing element symbols.

In 2015, an International Union of Pure and Applied Chemistry (IUPAC) Task Group was formed to develop nomenclature recommendations for homodetic cyclic peptides produced from ribosomal precursors. Delegates of the 2015 International Conference on Circular Proteins (ICCP) were presented with the strengths and weaknesses of four published approaches to homodetic cyclic peptide nomenclature, and a summary of the ensuing discussion is presented here. This interim report presents a potentially novel suggestion-the use of Cahn-Ingold-Prelog rules to specify amino acid priority in homodetic peptides for consistent numbering. Indeed, this might be the first extension of the Cahn-Ingold-Prelog rules in five decades. The authors invite interested parties to contact the corresponding author with suggestions for the improvement of the proposed nomenclature; these ideas will be discussed and considered for inclusion in the final report.

It is always a challenge to determine the total cellulase activity efficiently without reducing accuracy. The most common total cellulase activity assay is the filter paper assay (FPA) established by the International Union of Pure and Applied Chemistry (IUPAC). A new procedure to measure the FPA with microplate-based assay was studied in this work, which followed the main idea of IUPAC to dilute cellulase preparation to get fixed glucose release. FPAs of six cellulase preparations were determined with the microplate-based assay. It is shown that FPAs of cellulase Youtell, RCconc, R-10, Lerkam, Yishui and Sinopharm were 67.9, 46.0, 46.1, 27.4, 7.6 and 8.0 IU/ml respectively. There was no significant difference at the 95% confidence level between the FPA determined with IUPAC and the microplate-based assay. It could be concluded that the FPA could be determined by the microplate-based assay with the same accuracy and much more efficiency compared with that by IUPAC.