Search

Single crystals of Yb3+-doped Cs2NaScF6 are synthesized under hydrothermal conditions and dopant Yb3+ ions are studied using electron paramagnetic resonance spectroscopy. The paramagnetic Yb3+ center of cubic symmetry is detected. The parameters of the corresponding spin Hamiltonians and the ground state Г6 are determined. A structural model of the complex under study is proposed. The experimental results are analyzed by comparison with those for the paramagnetic Yb3+ ion in other lattices. [ABSTRACT FROM AUTHOR]

A CsCaF3 single crystal doped with Nd3+ ions is studied using electron paramagnetic resonance spectroscopy. A paramagnetic Nd3+ center of trigonal symmetry is recorded. The parameters of the corresponding spin Hamiltonians, the ground states and their wave functions are determined. Structural models of the observed complexes are proposed. The experimental results are analyzed in comparison with those for the same paramagnetic ion in other lattices. [ABSTRACT FROM AUTHOR]

The EPR study of impurity Dy3+ and Er3+ ions in single-crystal Cs2NaYF6 is reported. Cubic paramagnetic centers of Dy3+ and Er3+ ions are detected and parameters of relevant spin Hamiltonians for the Г6 (Dy3+) and Г8 (Er3+) states are determined. [ABSTRACT FROM AUTHOR]

The railgun launch of a solid armature is conventionally divided into two stages, namely, the initial stage, where a metallic contact is retained between the armature and the rails, and the second, starting at a velocity ~0.3-2 km/s, where the contact occurs through the arc plasma. While a variety of reasons for the transition were considered (a-spots, velocity skin effect etc.), no universally accepted physical picture supported by experiment has thus far been formulated. We showed experimentally that under usual launch parameters (current density ~[10.sup.4]-[10.sup.6] A/[cm.sup.2], current rise time ~[10.sup.-5]-[10.sup.-3] s), three-dimensional MHD instabilities form in the contact gap because of the absence of shear resistance, which result in the formation, collapse, and, eventually, explosion of pinch waists [E. M. Drobyshevski et al. Tech. Phys. Letts., 25(3), 245, 1999]. The destruction of the pinch waists gives rise not only to termination of current flow from the armature to the rail through the metal and transformation of the metallic contact in the armature/rail interface into an arc gap, but to ejection of the liquid metal and dusty plasma from the gap forward and back into the railgun bore as well. Even in the absence of MHD instabilities, armature material can be shed due to very inhomogeneous distribution of fields of thermal, electric, and dynamic parameters in the armature body [E. M. Drobyshevski et al. Tech. Phys. Letts., 25(4), 260, 1999]. Appearance of easily-ionized matter in the bore results in the formation of shunting arcs there, which naturally reduce the armature launching efficiency. Note that the transition to the arc regime involves not only the rail/armature interface but the launch process as a whole. The new physics revealed by us in the railgun solid-armature launch transition to the arc regime provides a basis for a purposeful search for ways of increasing the launch efficiency. Index Terms--3D MHD, arc mode, pinch instability, shunting arcs.

Measurements and inspection in production must be rapid, robust and automated. In this paper a new method is proposed to automatically detect screw threads in 3D density fields obtained from computed tomography measurement devices. The described method can be used to automate many operations during screw thread inspection process and drastically reduce operator's influence on the measurement process resulting in lower measurement times and increased repeatability. [ABSTRACT FROM AUTHOR]

CaF2 crystals doped with Yb3+ ions have been studied by electron paramagnetic resonance (EPR) and optical spectroscopy. EPR spectra of paramagnetic centers (PCs) for cubic (Tc) and tetragonal (Ttet) symmetries were identified. Empirical energy level diagrams were established and crystal field parameters were determined. Information on the CaF2∶Yb3+ phonon spectra was obtained from the electron-vibrational structure of the optical spectra. The crystal field parameters were used to analyze the crystal lattice distortions in the vicinity of the Yb3+ ion. Within the framework of a superposition model, it is established that four F− ions located symmetrically with respect to the fourfold axis from the side of the ion-compensator approach the impurity ion and deviate from the PC axis. The second set of four fluorine ions also approaches the Yb3+ ion and the PC axis. The ion-compensator F− also approaches considerably the impurity ion. [ABSTRACT FROM AUTHOR]

ENDOR measurements on the19F− nuclei in the first four shells of KZnF3 containing Dy3+ ions in the cubic site are reported. The values and signs of the hyperfine and transferred hyperfine interaction parameters are determined. The local deformation of the crystal lattice in the vicinity of the impurity ion is estimated. The theoretical analysis of the THFI parameters for the first coordination shell of the F− ions has been carried out. For the Dy3+ ion the influence of spin polarization of the closed 5s and 5p shells is considered for the first time. Spin polarization is shown to play a significant role in the mechanisms of rare-earth ion-ligand coupling. [ABSTRACT FROM AUTHOR]

Experimental evidence is presented in support of the hypothesis that the main factor determining the flow of physical processes on the interface of a sliding solid-state contact carrying a ∼0.1- 1 MA/cm² current is the sausage-type MHD pinch instability. It leads to the appearance and explosive destruction of tightening (quasi) liquid constrictions connecting the contact surfaces, so that under magnetic-suspension conditions the sliding of the latter relative to one another is virtually contact-free on the greater portion of their area. [ABSTRACT FROM AUTHOR]

Utilizing the W(CO)5 group as a promoter, we have established a straightforward pathway for the conversion of simple 1-alkyl-1,2-diphospholes to P,P-bidentate caged phosphines via [4+2] cycloaddition reactions. Furthermore, during the course of our investigation, we have observed a rare instance of isomerization, wherein the W(CO)5 migrates between the two phosphorus atoms in pentacarbonyl(1-alkyl-1,2-diphosphole)tungsten(0). This intriguing phenomenon has been thoroughly investigated using variable-temperature 31P NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The changes in the properties of copper and its alloys as a result of severe plastic deformation (SPD) are reviewed. The literature review shows that contemporary materials science is aimed at solving the problem of producing ultrafine-grained materials with high-angle grain boundaries. With using of the methods of severe plastic deformation, it is possible to obtain so-called bulk nanostructured materials with grain sizes of 0.1-0.2 microns and specific substructures containing the lattice and grain-boundary dislocations. Such structures are characterised by large elastic distortions of the crystal lattice. It is believed that such fine-grained structures should simultaneously provide a high level of plastic and strength characteristics due to special stressed high-angle grains. The article discusses SPD methods such as torsion with shear, equal-channel angular pressing, screw extrusion, all-round forging, rolling with shear, etc. Among the most significant results of SPD, it is worth highlighting the increase in strength, fatigue resistance and elastic properties of the material. These changes make copper and its alloys subjected to SPD very attractive for use in many industries, including electrical engineering, aviation, medicine, etc. [ABSTRACT FROM AUTHOR]

Simple Summary: This review offers a thorough examination of the potential role and structural properties of MGMT, the progression in targeting MGMT, and the interactions between MGMT and DNA repair pathways involved in processing DNA lesions. O6-methylguanine-DNA methyltransferase (MGMT or AGT) is a DNA repair protein with the capability to remove alkyl groups from O6-AlkylG adducts. Moreover, MGMT plays a crucial role in repairing DNA damage induced by methylating agents like temozolomide and chloroethylating agents such as carmustine, and thereby contributes to chemotherapeutic resistance when these agents are used. This review delves into the structural roles and repair mechanisms of MGMT, with emphasis on the potential structural and functional roles of the N-terminal domain of MGMT. It also explores the development of cancer therapeutic strategies that target MGMT. Finally, it discusses the intriguing crosstalk between MGMT and other DNA repair pathways. [ABSTRACT FROM AUTHOR]

DNA alkyltransferase and alkyltransferase-like family proteins are responsible for the repair of highly mutagenic and cytotoxic O6-alkylguanine and O4-alkylthymine bases in DNA. Their mechanism involves binding to the damaged DNA and flipping the base out of the DNA helix into the active site pocket in the protein. Alkyltransferases then directly and irreversibly transfer the alkyl group from the base to the active site cysteine residue. In contrast, alkyltransferase-like proteins recruit nucleotide excision repair components for O6-alkylguanine elimination. One or more of these proteins are found in all kingdoms of life, and where this has been determined, their overall DNA repair mechanism is strictly conserved between organisms. Nevertheless, between species, subtle as well as more extensive differences that affect target lesion preferences and/or introduce additional protein functions have evolved. Examining these differences and their functional consequences is intricately entwined with understanding the details of their DNA repair mechanism(s) and their biological roles. In this review, we will present and discuss various aspects of the current status of knowledge on this intriguing protein family. [ABSTRACT FROM AUTHOR]

Abstract—A computational and experimental estimation of the thickness of coating formed by electrocontact welding of a metal woven mesh onto bronze parts is carried out. The calculated coating thickness of the metal woven mesh is shown to correlate quite well with the coating thickness experimentally formed at the optimum electrocontact welding parameters. [ABSTRACT FROM AUTHOR]

Some features of the formation of a coating and its joint with the base metal during the reconditioning of bronze parts by electrocontact welding of woven metal gauze are considered. The cohesive strength of the coating is shown to be equal to the strength of the base metal, and the joint zone has no defects such as pores, cracks, faulty fusion, and discontinuities. A technology for reconditioning of worn bronze bushings has been developed and tested at production site. [ABSTRACT FROM AUTHOR]

A model-algorithmic software for the automated electric drive of the solar-tracking system without light-sensitive sensors for areas with frequent deterioration of weather conditions has been developed. Dependences are derived that allow determining the azimuth and angle of declination of the Sun's rays from the number of the day in the year and the time of day for any latitude of the globe. A universal algorithm for the operation of the positioning system has been developed and presented in the form of a flowchart. The applicability of the obtained model-algorithmic support is illustrated using the example of a two-linear solar tracker rotation system. [ABSTRACT FROM AUTHOR]

Based on the results of the published literature and production experience, technical and technological measures were developed and implemented to reduce the «rolled-in scale» defect: collectors with water descaling nozzles for removing furnace scale were replaced with new ones manufactured by Spraing Systems; the scheme of operation of hydraulic descalings has been changed; the specific impact force of jets was increased and the distance from the nozzles to the slab surface was reduced. These measures gave significant reduction of defective goods by a total of 55%. [ABSTRACT FROM AUTHOR]

Cementitious composites have been the prevalent field of research in recent eras due to their excellent bending and high strains. However, textile reinforcement requires materials with fine grain size to make proper binding between the yarns in the textile reinforcement and improve the strength characteristics. This concern has led to the development of fine-grained cementitious composites by dispersing chopped basalt fiber to improve strain-hardening capabilities with reduced voids. The basalt fiber content is varied by 0, 0.2, 0.4, 0.5 and 1% to the volume of the cementitious matrix. Various testing methods have evaluated the mechanical and microstructural properties of fine-grained cementitious composites with basalt fiber. Adding basalt fiber up to 0.4% to the volume of the matrix improves the compressive, split tensile, flexural strength and dynamic modulus of elasticity compared to the controlled cementitious matrix. Also, higher fiber content escalated the impact resistance and degree of carbonation. From the results, obtained basalt fiber reinforced fine-grained cementitious composites have higher mechanical characteristics, and the particles are densely packed compared to cementitious composites. Thus it provides good bonding between the textile reinforcement and helps to construct thin structural elements. [ABSTRACT FROM AUTHOR]

Aiming at the low efficiency of manual measurement of threads and the lack of practicability in machine vision measurement before, online size measurement of threads at the end of sucker rods based on machine vision was studied. A robotic arm is used to carry an optical device to achieve high-quality image acquisition of threads. Based on the prior knowledge of the thread profile angle, the directional edge detection operator is customized to achieve the accurate detection of the left and right edges of the thread. Noise filtering, sorting, and left and right edge-matching algorithms based on connected domains are developed to eliminate the interference effects of electrostatic dust and oil pollution in online measurement, and the dimension of thread profile angles, pitches, major diameters, and minor diameters can be precisely calculated. The experimental results show that the screw thread parameter measurement time is about 0.13 s; the maximum and minimum average errors of the thread angles are 0.011° and 0.632°, respectively; and the total average deviation is less than 0.08°. For the screw thread pitch, major diameter, minor diameter, and pitch diameter parameter measurement, the deviation of the measurement results between the proposed method and the universal tool microscope (UTM) method is less than 10 μm. It fully proves the effectiveness and accuracy of the method in this paper and, at the same time, shows that the method has good real-time performance and high application significance, which lays a good foundation for the subsequent online thread measurement. [ABSTRACT FROM AUTHOR]

Numerous genes required for sexual reproduction remain to be identified even in simple model species like Schizosaccharomyces pombe. To address this, we developed an assay in S. pombe that couples transposon mutagenesis with high-throughput sequencing (TN-seq) to quantitatively measure the fitness contribution of nonessential genes across the genome to sexual reproduction. This approach identified 532 genes that contribute to sex, including more than 200 that were not previously annotated to be involved in the process, of which more than 150 have orthologs in vertebrates. Among our verified hits was an uncharacterized gene, ifs1 (important for sex), that is required for spore viability. In two other hits, plb1 and alg9, we observed a novel mutant phenotype of poor spore health wherein viable spores are produced, but the spores exhibit low fitness and are rapidly outcompeted by wild type. Finally, we fortuitously discovered that a gene previously thought to be essential, sdg1 (social distancing gene), is instead required for growth at low cell densities and can be rescued by conditioned medium. Our assay will be valuable in further studies of sexual reproduction in S. pombe and identifies multiple candidate genes that could contribute to sexual reproduction in other eukaryotes, including humans. Author summary: Sex is absolutely required for many organisms, including humans, to reproduce. However, we still lack a complete understanding of the genetic contributions to sexual reproduction, even in many model organisms. Here we use a high-throughput insertional mutagenesis approach to measure the consequences during sexual reproduction of gene disruption across the genome in fission yeast. As a result, we identified hundreds of novel genes as contributing to sexual reproduction. While we identified a mutant with the expected loss of spore viability phenotype, we also demonstrated that disruption of some of these genes resulted in viable but low-quality spores (analogous to gametes like sperm in humans). In addition, we also identified a gene that was not required for sex itself but was instead required for cells to grow at low density. We propose that this mutant is a representative of a new class of genes that we refer to as "social distancing genes" because they are unable to grow without the presence of neighbors. In sum, this work presents genome-wide measurement of the genetic contributions to sex in fission yeast. [ABSTRACT FROM AUTHOR]

The development of low-carbon alkali-activated binders based on production waste is one of the most sought-after areas of development of building materials science. The article examines the results of studies of the structures of cupola dust and the assessment of its ability to hydrate when exposed to alkaline activation. Technological preparation of dust by sifting it through a 0.16 mm sieve and subsequent mechanical activation for 120 s to a specific surface area of 733 m2/kg is proposed. The best results were shown by the composition of cupola dust with an alkaline activator of 50 wt.% 8.3 M NaOH and 50 wt.% Na2SiO3. After 28 days of natural hardening for this composition, the bending strength was 12.7 MPa and the compressive strength was 68.3 MPa. The analysis of the influence of hardening conditions showed that the temperature–humidity treatment of concrete at a temperature of 90 °C for 12 h accelerates the process of curing to 80–90% of natural conditions. The porosity of the samples after heating was established, which is 24–25%. The mineralogical composition of the products of the cement matrix structure's formation, which is represented by minerals of the zeolite group, was specified. [ABSTRACT FROM AUTHOR]

Elevated serum urate (hyperuricemia) promotes crystalline monosodium urate tissue deposits and gout, with associated inflammation and increased mortality. To identify modifiers of uric acid pathologies, we performed a fly Genome-Wide Association Study (GWAS) on purine metabolites using the Drosophila Genetic Reference Panel strains. We tested the candidate genes using the Drosophila melanogaster model of hyperuricemia and uric acid crystallization ("concretion formation") in the kidney-like Malpighian tubule. Medusa (mda) activity increased urate levels and inflammatory response programming. Conversely, whole-body mda knockdown decreased purine synthesis precursor phosphoribosyl pyrophosphate, uric acid, and guanosine levels; limited formation of aggregated uric acid concretions; and was sufficient to rescue lifespan reduction in the fly hyperuricemia and gout model. Levels of mda homolog FAM214A were elevated in inflammatory M1- and reduced in anti-inflammatory M2-differentiated mouse bone marrow macrophages, and influenced intracellular uric acid levels in human HepG2 transformed hepatocytes. In conclusion, mda/FAM214A acts in a conserved manner to regulate purine metabolism, promotes disease driven by hyperuricemia and associated tissue inflammation, and provides a potential novel target for uric acid–driven pathologies. [ABSTRACT FROM AUTHOR]

Molecular and crystal structures of the following three cyclic compounds with condensed naphthyl fragments are studied: crystals of 1H,5H-naphtho[1,8-ef][1,3]dithiocine and 1H,5H-naphtho[1,8-ef][1,2,3]trithiocine, and an isomer of the latter compound with a seven-membered heterocycle 1,5-dihydronaphtho[2,3-e][1,2,3]trithiepine. The crystals of the first two compounds are isostructural. It is shown that eight-membered heterocycles and the seven-membered ring in the sulfur-containing molecules occur in boat and chair conformations, respectively, in contrast to acetals of a similar structure. The crystal structure of the studied compounds is determined by dispersion Van der Waals interactions. [ABSTRACT FROM AUTHOR]

Bacteria use various strategies to become antibiotic resistant. The molecular details of these strategies are not fully understood. We can increase our understanding by investigating the same strategies found in antibiotic‐producing bacteria. In this work, we characterize the self‐resistance protein Ecm16 encoded by echinomycin‐producing bacteria. Ecm16 is a structural homolog of the nucleotide excision repair protein UvrA. Expression of ecm16 in the heterologous system Escherichia coli was sufficient to render resistance against echinomycin. Ecm16 binds DNA (double‐stranded and single‐stranded) using a nucleotide‐independent binding mode. Ecm16's binding affinity for DNA increased by 1.7‐fold when the DNA is intercalated with echinomycin. Ecm16 can render resistance against echinomycin toxicity independently of the nucleotide excision repair system. Similar to UvrA, Ecm16 has ATPase activity, and this activity is essential for Ecm16's ability to render echinomycin resistance. Notably, UvrA and Ecm16 were unable to complement each other's function. Together, our findings identify new mechanistic details of how a refurbished DNA repair protein Ecm16 can specifically render resistance to the DNA intercalator echinomycin. [ABSTRACT FROM AUTHOR]

During meiosis, homologous chromosomes must recognize, pair, and recombine with one another to ensure the formation of inter-homologue crossover events, which, together with sister chromatid cohesion, promote correct chromosome orientation on the first meiotic spindle. Crossover formation requires the assembly of axial elements, proteinaceous structures that assemble along the length of each chromosome during early meiosis, as well as checkpoint mechanisms that control meiotic progression by monitoring pairing and recombination intermediates. A conserved family of proteins defined by the presence of a HORMA (HOp1, Rev7, MAd2) domain, referred to as HORMADs, associate with axial elements to control key events of meiotic prophase. The highly conserved HORMA domain comprises a flexible safety belt sequence, enabling it to adopt at least two of the following protein conformations: one closed, where the safety belt encircles a small peptide motif present within an interacting protein, causing its topological entrapment, and the other open, where the safety belt is reorganized and no interactor is trapped. Although functional studies in multiple organisms have revealed that HORMADs are crucial regulators of meiosis, the mechanisms by which HORMADs implement key meiotic events remain poorly understood. In this review, we summarize protein complexes formed by HORMADs, discuss their roles during meiosis in different organisms, draw comparisons to better characterize non-meiotic HORMADs (MAD2 and REV7), and highlight possible areas for future research. [ABSTRACT FROM AUTHOR]

The structural phase transition has been observed for the first time in the Rb2NaYF6 crystal and studied by EPR and optical spectroscopy. EPR spectra of Dy3+ and Yb3+ ions present as unintentional dopants in the nominally undoped crystal and forming tetragonal paramagnetic centers have been identified. A characteristic splitting of some optical lines has been observed in the temperature dependence of the Yb3+ optical spectra. It indicates the splitting of the cubic quartet energy levels of Yb3+ ions by the tetragonal crystal field. The empirical schemes of the energy levels for cubic and tetragonal paramagnetic centers of Yb3+ ions have been established and parameters of the corresponding crystal fields have been determined. The latter have been used for analyzing the crystal lattice distortions occurring in the vicinity of the Yb3+ ion during the phase transition. It has been established using the superposition model that the nearest octahedral environment of the Yb3+ ion is distorted as follows: the fluorine ions are rotated by the angle of 2.1° around the fourfold axis; the F- ions located symmetrically in the plane perpendicular to the rotation axis approach the dopant by 0.0014 nm, whereas the F- ions located on the rotation axis move away by 0.0028 nm. It has been concluded that the studied phase transition includes the critical rotations of the octahedral F groups and noncritical displacement of atoms in the rotated fluorine octahedra. [ABSTRACT FROM AUTHOR]

Organophosphorus compounds play an important role in the modern chemical industry and have a broad range of applications as flame retardants, agrochemicals, and chemical warfare agents. Unfortunately, they still present a big concern from a safety and security perspective considering their high toxicity to humans and the environment. Because of the former record and the persisting risks of some of these chemicals being used as weapons of mass destruction, the chemical weapons convention implemented by the organisation for the prohibition of chemical weapons, has classified a wide range of these chemicals as substances subject to a stringent verification regime. The existing practices for the production, detection and decontamination or destruction of unwanted organophosphorus compounds require high safety and security standards, which are not always attained only by sound management practices. The present review highlights the contribution made by the emerging research and early technology development in the field of green chemistry concerning these chemicals. Firstly, the advances regarding the safe synthesis of these compounds are covered not only due to their extensive legal commercial use but also as reference chemicals in verification processes. Aspects such as greener starting reactants, microwave irradiation, electrochemical synthesis and the use of ionic liquids are among the most promising alternatives. Another topic addressed is the decontamination of these toxic agents in the case of undesired stockpiles, for example, seeking their safe neutralization using mild conditions. The use of catalysts (derived from enzymes, metal–organic frameworks, polyoxometalates, nanomaterials, polymers, etc.) and continuous flow systems stand out. Finally, the greener detection of organophosphorus compounds is presented, which is relevant for inspection procedures regarding their prohibited use or misuse. This review is focused on the sustainable preparation of organophosphorus compounds and faster and cheaper architecture with lower detection limits for their detection, relying on integrated systems for multiple responses and facile applications such as wearable devices. Overall, the developments summarized provide a guide for researchers and the industry in this field, while also attracting the attention of policy makers to the undisclosed potential of green chemistry in this security sensitive domain. However, despite the progress, continuous efforts are imperative for the further development of intrinsically safer, more efficient and sustainable technologies in this field. [ABSTRACT FROM AUTHOR]

The influence of the parameters of a through technology on a rolled-in scale defect is analyzed. To study the influence of the temperature behind stand no. 6 of the 2000 hot-rolling mill in sheet rolling shop no. 10 of PAO MMK on the rejection according to this defect, the temperature in the range 1030–1070°C is maintained on rolled strips of steel grades 08Yu and 08(sp, ps, kp), and the products to be processed are then delivered to the 2000 cold-rolling mill in sheet rolling shop no. 5. To study the influence of the reeling temperature on the scale layer thickness, selective sampling from rolls wound with different reeling temperatures is carried out. An analysis of the production of semifinished rolled products for cold rolling with a rolled-in scale defect and metallographic studies have shown that the main cause for the formation of this defect during hot rolling is a high reeling temperature of 604.7 t (24%). The rolled-in scale defect depth is mainly no more than 0.02 mm and is 81 and 67% of the initial cause of scab and underpickling, respectively. An analysis of the influence of the strip temperature behind stand no. 6 on rolling semifinished rolled tin plates shows that a decrease in the temperature decreases the rejection according to the rolled-in scale defect in sheet rolling shop no. 3 and in the coating shop by 3.7 times for the semifinished rolled products upon annealing in bell furnaces and by 1.9 times for annealing in a continuous annealing furnace. The study of the influence of the reeling temperature on the scale layer thickness showed that a change in the reeling temperature from 560 to 730°C leads to an increase in the scale layer from 55.15 to 89.45 g/m2. To improve the surface quality of the finished electro-tinned tin, an experimental technology is proposed: the reeling temperature for semifinished rolled tin plates in the flow of annealing in bell furnaces decreases to 630–660°C instead of 660–690°C according to a standard technology. [ABSTRACT FROM AUTHOR]

Abstract—The article covers the events related to the launch of the Luna-17 automatic space station with Lunokhod 1 on board in 1970. The memoirs of a member of the Lunokhod 1 control crew shed light on some details of the implementation of the research program which paved the way for the world science of lunar exploration and gave invaluable experience for the development of the next generation of planetary rovers. [ABSTRACT FROM AUTHOR]

Evolutionary selection ensures specificity and efficiency in dynamic metastable macromolecular machines that repair DNA damage without releasing toxic and mutagenic intermediates. Here we examine non‐homologous end joining (NHEJ) as the primary conserved DNA double‐strand break (DSB) repair process in human cells. NHEJ has exemplary key roles in networks determining the development, outcome of cancer treatments by DSB‐inducing agents, generation of antibody and T‐cell receptor diversity, and innate immune response for RNA viruses. We determine mechanistic insights into NHEJ structural biochemistry focusing upon advanced small angle X‐ray scattering (SAXS) results combined with X‐ray crystallography (MX) and cryo‐electron microscopy (cryo‐EM). SAXS coupled to atomic structures enables integrated structural biology for objective quantitative assessment of conformational ensembles and assemblies in solution, intra‐molecular distances, structural similarity, functional disorder, conformational switching, and flexibility. Importantly, NHEJ complexes in solution undergo larger allosteric transitions than seen in their cryo‐EM or MX structures. In the long‐range synaptic complex, X‐ray repair cross‐complementing 4 (XRCC4) plus XRCC4‐like‐factor (XLF) form a flexible bridge and linchpin for DNA ends bound to KU heterodimer (Ku70/80) and DNA‐PKcs (DNA‐dependent protein kinase catalytic subunit). Upon binding two DNA ends, auto‐phosphorylation opens DNA‐PKcs dimer licensing NHEJ via concerted conformational transformations of XLF‐XRCC4, XLF–Ku80, and LigIVBRCT–Ku70 interfaces. Integrated structures reveal multifunctional roles for disordered linkers and modular dynamic interfaces promoting DSB end processing and alignment into the short‐range complex for ligation by LigIV. Integrated findings define dynamic assemblies fundamental to designing separation‐of‐function mutants and allosteric inhibitors targeting conformational transitions in multifunctional complexes. [ABSTRACT FROM AUTHOR]

The novel approach for holistic screw thread calibrations developed by the Physikalisch-Technische Bundesanstalt was published in 2019. A significant achievement has been made in order to meet increasing demands in manufacturing processes and quality assurance, particularly when workpieces with complex geometries are under inspection. This article deals with the verification of the previously presented three-dimensional calibration procedure for screw threads. Screw thread pitch diameters, the lead and flank angles are compared to those determined by the standardized method based on line-like, rather two-dimensional measurements and evaluation. In order to provide a reliable basis for the verification, one thread gauge was calibrated under laboratory conditions for precision metrology. Additionally, calibrations were conducted by three alternating operators on three different coordinate measuring machines to investigate the influence by user and machine. The resulting normalized errors of screw thread determinants under test and reference values are significantly smaller than 0.5 which indicates a high level of agreement. [ABSTRACT FROM AUTHOR]

A homologous series of cationic surfactants with a pyrrolidinium head group containing a hydroxyethyl moiety was studied for the solubilization of nonsteroidal anti-inflammatory drugs, indomethacin and meloxicam, and the antioxidant quercetin. For indomethacin, the solubilization capacity linearly increases with increasing number of carbon atoms in the alkyl chain. In the case of quercetin and meloxicam, the solubilization capacity passes through a maximum for the hexadecyl derivative. The possibility of solubilization by premicellar surfactant aggregates was shown for indomethacin and meloxicam. [ABSTRACT FROM AUTHOR]

A new additive in the form of a perforated steel strip, which is easily deformed plastically on welding, is proposed for the restoration of worn parts by electric contact welding, which ensures a high strength of the welded joint formed in a solid phase. The optimum parameters of the filler strip are found and the rational technological conditions of its welding are determined. [ABSTRACT FROM AUTHOR]