In the last few decades, new discoveries have pushed beginning of biface-rich European Acheulian from 500 thousand years (ka) ago back to at least 700 ka, and possibly 1 million (Ma) ago. It remains, however, unclear date if handaxes arrived in Europe as a fully developed technology or they evolved locally core-and-flake industries. This issue is also linked with another long-standing debate on existence behavioral, cognitive, social meaning chronological trend for increased handaxe symmetry...

HIV-1 protease inhibitors are major players among the antiviral therapies used against acquired immunodeficiency syndrome (AIDS). As such, crystallographic coordinates of hundreds complexes with miscellaneous ligands have been resolved and uploaded to Protein Data Bank. Herein, machine learning (ML) models were constructed based on 291 inhibitor >2500 molecular descriptors subsequently predict binding affinity 274 additional protease–inhibitor for which inhibition constants not measured....

We present a comprehensive and updated Python-based open software to calculate continuous symmetry measures (CSMs) their related chirality measure (CCM) of molecules across chemistry. These descriptors are used quantify distortion levels molecular structures on scale were proven insightful in numerous studies. The input information includes the coordinates geometry desired cyclic point group (

In this paper we describe the learning process of a group experienced chemistry teachers in specially designed workshop on molecular symmetry and continuous symmetry. The was based interactive visualization tools that allow molecules their elements to be rotated three dimensions. topic is new field study provides quantitative description distance specific structure from perfect Using novel online tools, were able perform these calculations with emphasis chemistry, rather than mathematics...

Professional development courses help teachers integrate new content knowledge into the high-school curriculum. Designing practical online for this purpose is challenging, particularly in emerging fields such as nanotechnology. In study, we evaluated a course three complementary dimensions: (1) knowledge, (2) complexity of learners' understanding, and (3) difficulties during course. We first aspect using pre–post-knowledge test, second Structure Observed Learning Outcome (SOLO) taxonomy...

Abstract The chemical sciences integrate numerous pieces of structural data into families compounds, and countless experimental results reactive processes ground rules. Collecting these information, analyzing them, making the relevant contextual connections between them is in heart chemistry education. Here we emphasize contribution technology, more specifically, databases for enhancing learning processes. Several important, open access, are described detail examples using class provided. In...

This study examines chemistry lecturers' considerations for using open educational resources (OER) in their teaching. Recent technological developments provide innovative approaches teaching and visualizing chemical phenomena. End users' improved ability to upload information online enables integration of various pedagogical models learning theories. These improvements strengthen the need up-to-date evaluation tools websites. Building on existing taxonomies, a set new criteria materials was...

Abstract Woodward–Hoffmann (WH) rules provide strict symmetry selection rules: when they are obeyed, a reaction proceeds; not there is no reaction. However, the voluminous experimental literature provides ample evidence that compliance to requirements an obstacle for concerted proceed, and therefore idea has developed it enough have certain degree of required reactivity. Here we quantitative link, show as one deviates from desired symmetry, enthalpy activation increases, is, reactions slow...

Many reactions feature symmetry variation along the reaction path on potential energy surface. The interconversion of point group stationary points can be characteristic these processes. Increasing temperature, however, leads to loss in its traditional yes–no language. We find that such cases instantaneous distance molecular structure from symmetric counterpart is a suitable collective variable describe process. show this quantity, continuous measure (CSM), has positive linear relationship...

Abstract The interdisciplinary field of computational chemistry links many facets and provides unique insights into structure, mechanisms, dynamics, the interplay between them. Various approaches were proposed for integrating in undergraduate classroom, all highlight benefits including it curriculum. This study focuses on desirable learning outcomes, defines a structural framework literacy . Based this approach analysis pedagogical selected studies that implemented classrooms is presented....

Abstract Quantifying imperfect symmetry of molecules can help explore the sources, roles and extent structural distortion. Based on established methodology continuous chirality measures, we develop a set three-dimensional molecular descriptors to estimate distortion large structures. These geometrical quantify gap between desirable (or chirality) actual one. They are global parameters geometry, intuitively defined, have ability detect even minute changes given molecule across chemistry,...

A Website that helps students visualize and locate symmetry elements on three- dimensional molecular structures was developed. It includes textual explanations, an interactive example window a Microsoft-Excel based toolkit enables to draw in three dimensions. Preliminary qualitative research aimed at exploring how learned with this tool performed. found the three-dimensional graphical capabilities of (1) helped overcome difficulties visualization, (2) enabled find complex molecules generally...

We propose the notion that if asymmetry characterizes a concerted reaction, quantitative treatment in terms of continuous symmetry can bridge gap between Woodward-Hoffmann (WH) rules, originally formulated for symmetry-idealized unsubstituted reactants, and fact these rules hold much wider scope reactions. Instead focusing on conservation along minimum energy path, we suggest distortion with respect to original expected must attain certain minimal value, not necessarily zero. To demonstrate...

Ramachandran plots (RPs) map the wealth of conformations polypeptide backbone and are widely used to characterize protein structures. A limitation RPs is that they based solely on two dihedral angles for each amino acid residue provide therefore only a partial picture conformational richness protein. Here we extend structural RP analysis proteins from two-dimensional (2D) three-dimensional by adding quantitative degree chirality-the continuous chirality measure (CCM)-of at point in RP. This...

Ferrocene symmetry is commonly described as either eclipsed (D5h) or staggered (D5d), but this does not hold when substitution involved. Here we examine and quantify the effect of on geometry core structure ferrocene, provide means to distinguish between its various distortion paths. Continuous analysis 7418 substituted ferrocenes extracted from Cambridge Crystallographic Database was used explore twisting bending paths, well asymmetric bond stretch that deforms cyclopentadienyl rings....

Abstract A new approach to resolve and quantify the effect of temperature on both average, as well instantaneous, structure generally symmetric molecules is presented. The method employs efficient continuous symmetry measure, which shown here be capable separating temperature‐induced instantaneous disorders from other sources distortion, such Jahn−Teller effect. We demonstrate potential by studying two highly molecules: adamantane cyclopentadienyl anion their cationic states. Our results...

The degree of chirality protein backbone residues is used to enrich the Ramachandran plot (RP) and create three-dimensional chiral RPs with much more structural information. Detailed comparative analysis four classical (general, glycine, proline, pre-proline) provided, including statistical quantitative distributions in maps secondary structures. Our results show that points outlier levels represent special transitional folded such as α-helix kinks, twists β-strands, transition between A...

Symmetry of proteins, an important source their elegant structure and unique functions, is not as perfect it may seem. In the framework continuous symmetry, in which symmetry no longer a binary yes/no property, such imperfections can be quantified used global descriptor three-dimensional structure. We present improved algorithm for calculating measure proteins that takes into account complete set atoms including all side chains. Our method advantage protein sequence division peptides order...

A comprehensive analysis of crystallographic data 565 high-resolution protein homodimers comprised over 250,000 residues suggests that amino acids form two groups differ in their tendency to distort or symmetrize the structure homodimers. Residues first group tend homodimer and generally have long polar side chains. These include: Lys, Gln, Glu, Arg, Asn, Met, Ser, Thr Asp. second contribute symmetry are characterized by short aromatic Ile, Pro, His, Val, Cys, Leu, Trp, Tyr, Phe, Ala Gly....