Nondislocation origin of GaAs nanoindentation pop-in event

The present Letter demonstrates a pop-in event that is caused by a nanoindentation-induced phase transformation in GaAs, and not accompanied by any dislocation nucleation. Our computer simulations reveal the appearance of the new phase, documented by the structural correlation functions and visualization of the atomic positions. This challenges the orthodox view that the initial pop-in event reflects nucleation of dislocations or their movement, and has a bearing on materials where dislocation activity is not present.     

Sulphur isotope compositions of components of coal and S-isotope fractionation during its combustion and flue gas desulphurization

Sulphur isotope compositions were determined in two different Polish coals (hard coal and lignite) and by-products originating from their combustion. The desulphurization process was also investigated. It was demonstrated that desulphurization changes the isotopic composition of sulphur emitted in the form of SO(2) to the atmosphere even if the process is conducted in a different way (wet lime technology and electron beam method). This fact has to be considered in the studies regarding anthropogenic sulphur genesis and its fate in the environment.     

Fourier analysis of scratches generated on m‐GaN substrates during polishing

Generation of scratches on surface of m‐plane GaN substrates due to polishing was studied by atomic force microscopy (AFM). For epi‐ready substrates AFM images confirm a flat surface with the atomic step roughness while a lot of scratches are visible in AFM images for partially polished GaN substrates. The Fourier analysis of AFM images show that scratches propagate easier along {c‐plane} and {a‐plane} directions on m‐plane GaN surface. This observation is an evidence of anisotropy of mechanical properties of GaN crystals in the micro‐scale. This anisotropy is directly correlated with the symmetry and atomic arrangement of m‐plane GaN.     

Chemical Probing of the Human Sirtuin 5 Active Site Reveals Its Substrate Acyl Specificity and Peptide‐Based Inhibitors

Sirtuins are NAD⁺‐dependent deacetylases acting as sensors in metabolic pathways and stress response. In mammals there are seven isoforms. The mitochondrial sirtuin 5 is a weak deacetylase but a very efficient demalonylase and desuccinylase; however, its substrate acyl specificity has not been systematically analyzed. Herein, we investigated a carbamoyl phosphate synthetase 1 derived peptide substrate and modified the lysine side chain systematically to determine the acyl specificity of Sirt5. From that point we designed six potent peptide‐based inhibitors that interact with the NAD⁺ binding pocket. To characterize the interaction details causing the different substrate and inhibition properties we report several X‐ray crystal structures of Sirt5 complexed with these peptides. Our results reveal the Sirt5 acyl selectivity and its molecular basis and enable the design of inhibitors for Sirt5.     

Nature’s Chemical Signatures in Human Olfaction: A Foodborne Perspective for Future Biotechnology

The biocatalytic production of flavor naturals that determine chemosensory percepts of foods and beverages is an ever challenging target for academic and industrial research. Advances in chemical trace analysis and post‐genomic progress at the chemistry–biology interface revealed odor qualities of nature’s chemosensory entities to be defined by odorant‐induced olfactory receptor activity patterns. Beyond traditional views, this review and meta‐analysis now shows characteristic ratios of only about 3 to 40 genuine key odorants for each food, from a group of about 230 out of circa 10 000 food volatiles. This suggests the foodborn stimulus space has co‐evolved with, and roughly match our circa 400 olfactory receptors as best natural agonists. This perspective gives insight into nature’s chemical signatures of smell, provides the chemical odor codes of more than 220 food samples, and beyond addresses industrial implications for producing recombinants that fully reconstruct the natural odor signatures for use in flavors and fragrances, fully immersive interactive virtual environments, or humanoid bioelectronic noses.     

Mutant-Selective Allosteric EGFR Degraders are Effective Against a Broad Range of Drug-Resistant Mutations

Targeting epidermal growth factor receptor (EGFR) through an allosteric mechanism provides a potential therapeutic strategy to overcome drug-resistant EGFR mutations that emerge within the ATP binding site. Here, we develop an allosteric EGFR degrader, DDC-01-163, which can selectively inhibit the proliferation of L858R/T790M (L/T) mutant Ba/F3 cells while leaving wildtype EGFR Ba/F3 cells unaffected. DDC-01-163 is also effective against osimertinib-resistant cells with L/T/C797S and L/T/L718Q EGFR mutations. When combined with an ATP-site EGFR inhibitor, osimertinib, the anti-proliferative activity of DDC-01-163 against L858R/T790M EGFR-Ba/F3 cells is enhanced. Collectively, DDC-01-163 is a promising allosteric EGFR degrader with selective activity against various clinically relevant EGFR mutants as a single agent and when combined with an ATP-site inhibitor. Our data suggests that targeted protein degradation is a promising drug development approach for mutant EGFR.     

Back cover: Mn2+ or Mn3+? Investigating transition metal dissolution of manganese species in lithium ion battery electrolytes by capillary electrophoresis

A new CE method with ultraviolet–visible detection was developed in this study to investigate manganese dissolution in lithium ion battery electrolytes. The aqueous running buffer based on diphosphate showed excellent stabilization of labile Mn³⁺, even under electrophoretic conditions. The method was optimized regarding the concentration of diphosphate and modifier to obtain suitable signals for quantification. Additionally, the finally obtained method was applied on carbonate-based electrolytes samples. Dissolution experiments of the cathode material LiNi_0.5Mn_1.5O₄ (lithium nickel manganese oxide [LNMO]) in aqueous diphosphate buffer at defined pH were performed to investigate the effect of a transition metal-ion-scavenger on the oxidation state of dissolved manganese. Quantification of both Mn species revealed the formation of mainly Mn³⁺, which can be attributed to a comproportionation reaction of dissolved and complexed Mn²⁺ with Mn⁴⁺ at the surface of the LNMO structure. It was also shown that the formation of Mn³⁺ increased with lower pH. In contrast, dissolution experiments of LNMO in carbonate-based electrolytes containing LIPF₆ showed only dissolution of Mn²⁺.     

ToF‐SIMS spectrometry to observe fatty acid profiles of breast tissues in broiler chicken subjected to varied vegetable oil diet

This study is aimed to observe changes in fatty acid profiles by time of flight secondary ion mass spectrometry (ToF‐SIMS) in breast muscle tissues of broilers. Four different groups were identified. The source of fat in group I was soy oil (rich in linoleic acid, ω‐6), group II received linseed oil (ω‐3), and the third group was fed a mixture of the two mentioned oils. Broilers in the control group were fed with beef tallow, used in mass commercial production. The results reveal that the use of vegetable oils in animal nutrition determines the lipid profile of fatty acids. ToF‐SIMS measurements showed that the lipid profile of muscle fibers and intramuscular fat reflect the composition of fats used as feed additives. In both structures, the ratio of ω‐6/ω‐3 fatty acids, which is most favorable for human health, was found in the groups in which a mixture of vegetable oils and a supplement of linseed oil were used.     

Compromising Science by Ignorant Instrument Calibration—Need to Revisit Half a Century of Published XPS Data

X‐ray photoelectron spectroscopy (XPS) is an indispensable technique in modern materials science for the determination of chemical bonding as evidenced by more than 10 000 XPS papers published annually. A literature survey reveals that in the vast majority of cases an incorrect referencing of the binding energy scale is used, neglecting warnings that have been formulated from the early days of the technique. Consequences for the data reliability are disastrous and decades of XPS work require revisiting. The purpose of this Viewpoint is to highlight the existing problems, review the criticism and suggest ways forward.     

Bases,solvates and salts: new benzimidazole‐ and pyridine‐scaffolded ligands

The intermolecular interactions in the structures of a series of Schiff base ligands have been thoroughly studied. These ligands can be obtained in different forms, namely, as the free base 2‐[(2E)‐2‐(1H‐imidazol‐4‐ylmethylidene)‐1‐methylhydrazinyl]pyridine, C₁₀H₁₁N₅, 1 , the hydrates 2‐[(2E)‐2‐(1H‐imidazol‐2‐ylmethylidene)‐1‐methylhydrazinyl]‐1H‐benzimidazole monohydrate, C₁₂H₁₂N₆·H₂O, 2 , and 2‐{(2E)‐1‐methyl‐2‐[(1‐methyl‐1H‐imidazol‐2‐yl)methylidene]hydrazinyl}‐1H‐benzimidazole 1.25‐hydrate, C₁₃H₁₄N₆·1.25H₂O, 3 , the monocationic hydrate 5‐{(1E)‐[2‐(1H‐1,3‐benzodiazol‐2‐yl)‐2‐methylhydrazinylidene]methyl}‐1H‐imidazol‐3‐ium trifluoromethanesulfonate monohydrate, C₁₂H₁₃N₆⁺·CF₃O₃S^?·H₂O, 5 , and the dicationic 2‐{(2E)‐1‐methyl‐2‐[(1H‐imidazol‐3‐ium‐2‐yl)methylidene]hydrazinyl}pyridinium bis(trifluoromethanesulfonate), C₁₀H₁₃N₅²⁺·2CF₃O₃S^?, 6 . The connection between the forms and the preferred intermolecular interactions is described and further studied by means of the calculation of the interaction energies between the neutral and charged components of the crystal structures. These studies show that, in general, the most important contribution to the stabilization energy of the crystal is provided by π–π interactions, especially between charged ligands, while the details of the crystal architecture are influenced by directional interactions, especially relatively strong hydrogen bonds. In one of the structures, a very interesting example of the nontypical F…O interaction was found and its length, 2.859 (2) Å, is one of the shortest ever reported.