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Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title heteroleptic cuprous complex, [2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl‐κ2P,P′](2‐phenylpyridine‐κN)copper(I) hexafluoridophosphate, rac‐[Cu(C44H32P2)(C11H9N)]PF6, conventionally abbreviated rac‐[Cu(BINAP)(2‐PhPy)]PF6 (I), where BINAP and 2‐PhPy represent 2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl and 2‐phenylpyridine, respectively, is described. In this complex, the asymmetric unit consists of a hexafluoridophosphate anion and a heteroleptic cuprous complex cation, in which the cuprous centre in a CuP2N coordination triangle is coordinated by two P atoms from the BINAP ligand and by one N atom from the 2‐PhPy ligand. Time‐dependent density functional theory (TD–DFT) calculations show that the UV–Vis absorption of I should be attributed to ligand‐to‐ligand charge transfer (LLCT) characteristic excited states. It was also found that the paper‐based film of this complex exhibited obvious luminescence light‐up sensing for pyridine. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor in response to the paper "A comparison between experimental and theoretical aspherical-atom scattering factors for charge-density refinement of large molecules," by V. Pichon-Pesme and colleagues that compares the databank of pesudoatom parameters and theoretical approaches citing the different electrostatic properties.

This paper analyzes a common‐value, first‐price auction with state‐dependent participation. The number of bidders, which is unobservable to them, depends on the true value. For participation patterns with many bidders in each state, the bidding equilibrium may be of a "pooling" type—with high probability, the winning bid is the same across states and is below the ex ante expected value—or of a "partially revealing" type—with no significant atoms in the winning bid distribution and an expected winning bid increasing in the true value. Which of these forms will arise is determined by the likelihood ratio at the top of the signal distribution and the participation across states. We fully characterize this relation and show how the participation pattern determines the extent of information aggregation by the price. [ABSTRACT FROM AUTHOR]

Selecting active elements for filler metal is very important in soldering of ZrO2 ceramics. In this paper, the effects of Ti, Al, Cu, and Ag active elements on the bonding strength and electronic structures of soldered β‐Sn(100)/ZrO2(111) interface were studied via the method of first principle calculation. The work of adhesion (Wad) results show that the O2‐terminated interface is more stable than other kinds of interfaces. Then, the atoms of Ti, Al, Cu, and Ag were doped into the interface by replacing the Sn atom in situ. It is found that additions of Ti, Al, and Cu atoms can increase the Wad, and Ag atom has the opposite effect. From the results of heat of segregation, doping Ti and Al into the interface is stable in thermodynamics and doping Cu and Ag is not stable. The forming of strong ionic‐covalent Ti‐O and Al‐O bonding contributes to the increase of the interfacial adhesion strength. The calculation results indicate that Ti and Al can act as active elements in Sn to solder ZrO2. The Ti‐O and Al‐O compounds formed at interface can improve the wetting and bonding between Sn‐based solder and ZrO2 ceramics. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (LSBs) are widely regarded as promising next‐generation batteries due to their high theoretical specific capacity and low material cost. However, the practical applications of LSBs are limited by the shuttle effect of lithium polysulfides (LiPSs), electronic insulation of charge and discharge products, and slow LiPSs conversion reaction kinetics. Accordingly, the introduction of catalysts into LSBs is one of the effective strategy to solve the issues of the sluggished LiPS conversion. Because of their nearly 100% atom utilization and high electrocatalytic activity, single‐atom catalysts (SACs) have been widely used as reaction mediators for LSBs' reactions. Excitingly, the SACs with asymmetric coordination structures have exhibited intriguing electronic structures and superior catalytic activities when compared to the traditional M–N4 active sites. In this review, we systematically describe the recent advancements in the installation of asymmetrically coordinated single‐atom structure as reactions catalysts in LSBs, including asymmetrically nitrogen coordinated SACs, heteroatom coordinated SACs, support effective asymmetrically coordinated SACs, and bimetallic coordinated SACs. Particularly noteworthy is the discussion of the catalytic conversion mechanism of LiPSs spanning asymmetrically coordinated SACs. Finally, a perspective on the future developments of asymmetrically coordinated SACs in LSB applications is provided. [ABSTRACT FROM AUTHOR]

Single atomic catalysts have shown great potential in efficiently electro‐converting O2 to H2O2 with high selectivity. However, the impact of coordination environment and introduction of extra metallic aggregates on catalytic performance still remains unclear. Herein, first a series of carbon‐based catalysts with embedded coupling Ni single atomic sites and corresponding metallic nanoparticles at adjacent geometry is synthesized. Careful performance evaluation reveals NiSA/NiNP‐NSCNT catalyst with precisely controlled active centers of synergetic adjacent Ni‐N4S single sites and crystalline Ni nanoparticles exhibits a high H2O2 selectivity over 92.7% within a wide potential range (maximum selectivity can reach 98.4%). Theoretical studies uncover that spatially coupling single atomic NiN4S sites with metallic Ni aggregates in close proximity can optimize the adsorption behavior of key intermediates *OOH to achieve a nearly ideal binding strength, which thus affording a kinetically favorable pathway for H2O2 production. This strategy of manipulating the interaction between single atoms and metallic aggregates offers a promising direction to design new high‐performance catalysts for practical H2O2 electrosynthesis. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is a vital chemical for modern human society. It is conventionally produced by the energy‐ and emission‐intensive Haber–Bosch process. Alternatively, sustainable NH3 production from renewable electricity‐driven electrolyzers has emerged as a promising route. Particularly, NH3 synthesis from nitrate (NO3−), a common pollutant in water and soil, by the nitrate reduction reaction (NO3RR) has drawn wide attention. Among various catalysts demonstrated recently, copper (Cu)‐based catalysts have been recognized as attractive candidates due to their availability, good activity, high NH3 selectivity, and facile reaction kinetics. In this review, the recent progress of Cu‐based NO3RR catalysts from the reaction mechanistic fundamentals to various catalyst design strategies, aiming at providing an on‐time summary, is summarized, and perspectives that can guide the rational and on‐demand design of Cu‐ and other earth‐abundant metal‐based catalysts for selective NO3RR toward sustainable NH3 production are elucidated. [ABSTRACT FROM AUTHOR]

Nonconventional luminescent materials have been rising stars in organic luminophores due to their intrinsic characteristics, including water‐solubility, biocompatibility, and environmental friendliness and have shown potential applications in diverse fields. As an indispensable branch of nonconventional luminescent materials, polysiloxanes, which consist of electron‐rich auxochromic groups, have exhibited outstanding photophysical properties due to the unique silicon atoms. The flexible Si‐O bonds benefit the aggregation, and the empty 3d orbitals of Si atoms can generate coordination bonds including N → Si and O → Si, altering the electron delocalization of the material and improving the luminescent purity. Herein, we review the recent progress in luminescent polysiloxanes with different topologies and discuss the challenges and perspectives. With an emphasis on the driving force for the aggregation and the mechanism of tuned emissions, the role of Si atoms played in the nonconventional luminophores is highlighted. This review may provide new insights into the design of nonconventional luminescent materials and expand their further applications in sensing, biomedicine, lighting devices, etc. [ABSTRACT FROM AUTHOR]

- Ratios determined from counting a subset of atoms in a sample are positively biased relative to the true ratio in the sample (Ogliore et al. 2011). The relative magnitude of the bias is approximately equal to the inverse of the counts in the denominator of the ratio. SIMS studies of short-lived radionuclides are particularly subject to the problem of ratio bias because the abundance of the daughter element is low, resulting in low count rates. In this paper, we discuss how ratio bias propagates through mass-fractionation corrections into an isochron diagram, thereby affecting the inferred initial ratio of short-lived radionuclides. The slope of the biased isochron can be either too high or too low, depending on how it is calculated. We then reanalyze a variety of previously published data sets and discuss the extent to which they were affected by ratio bias. New, more accurate, results are presented for each study. In some cases, such as for 53Mn-53Cr in pallasite olivines and 60Fe-60Ni in chondrite sulfides, the apparent excesses of radiogenic isotopes originally reported disappear completely. Many of the reported initial 60Fe/56Fe ratios for chondrules from ordinary chondrites are no longer resolved from zero, though not all of them. Data for 10Be-10B in CAIs were only slightly affected by bias because of how they were reduced. Most of the data sets were recalculated using the ratio of the total counts, which increases the number of counts in the denominator isotope and reduces the bias. However, if the sum of counts is too low, the ratio may still be biased and a less-biased estimator, such as Beale's estimator, must be used. Ratio bias must be considered in designing the measurement protocol and reducing the data. One can still collect data in cycles to permit editing of the data and to monitor and correct for changes in ion-beam intensity, even if total counts are used to calculate the final ratio. The cycle data also provide a more robust estimate of the uncertainties from temporal variations in the secondary ion signal. [ABSTRACT FROM AUTHOR]

Coarsening of porosity during sintering has been observed in powder compacts of metallic, ceramic, and amorphous materials. Monitoring and modelling of the growth of individual (closed) pores in the late sintering stages are well established. Porosity is interconnected up to very high densities. Coarsening of the continuous pore space takes place during the initial and intermediate sintering stages. This coarsening is caused by localized transport of atoms or molecules (diffusion or viscous flow) as well as by bulk particle movement (rearrangement). Its quantitative exploration poses problems both experimentally and theoretically. Ways to characterize the geometry of the interconnected pore space and of closed pores are discussed with emphasis on stereological parameters. Recent and classical approaches, experimental findings with 2D model arrangements (as the formation and opening up of particle contacts, pore coarsening, and particle rearrangement) and some advances of computer simulations are discussed together with open questions. [ABSTRACT FROM AUTHOR]

Single transition metal (TM) atoms such as Fe, Co and Ni occupying a carbon divacancy in tetragonal graphene (TG) and bonded with four nitrogen atoms (TM@N4TG) as electrocatalysts are investigated by means of first-principles calculations. To consider the effect of solvent species on the local configuration of the active single metal, a thermodynamical full-landscape searching (TFLS) scheme is employed. The calculated thermodynamic overpotentials (ηtd) from our TFLS indicate that Co@N4TG displays high catalytic activity toward both oxygen evolution reaction (OER) and reduction reaction (ORR), with ηtd OER and ηtd ORR as 0.397 and 0.357 V, respectively. Its OER potential cannot be captured if only one four electron reaction loop (FERL) is considered. The actual active pathways do not always turn out to be the reactions starting from the bare site. Our findings demonstrate that TG is a promising support and TM confined TD can be used to design effective and cheap multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

Invited for this month's cover picture is the group of Paul L. A. Popelier from Manchester Institute of Biotechnology (UK). The cover picture shows the quantum topological atoms in a configuration of the complex HF⋅⋅⋅OH2, where F is green and O is red. Read the full text of their Full Paper at 10.1002/open.201800275. [ABSTRACT FROM AUTHOR]

Tuning the coordination structures of metal sites is intensively studied to improve the performances of single‐atom site catalysts (SASC). However, the pore structure of SASC, which is highly related to the accessibility of active sites, has received little attention. In this work, single‐atom ZnN4 sites embedded in P‐functionalized carbon with hollow‐wall and 3D ordered macroporous structure (denoted as H‐3DOM‐ZnN4/P‐C) are constructed. The creation of hollow walls in ordered macroporous structures can largely increase the external surface area to expose more active sites. The introduction of adjacent P atoms can optimize the electronic structure of ZnN4 sites through long‐rang regulation to enhance the intrinsic activity and selectivity. In the electrochemical CO2 reduction reaction, H‐3DOM‐ZnN4/P‐C exhibits high CO Faradaic efficiency over 90% in a wide potential window (500 mV) and a large turnover frequency up to 7.8 × 104 h−1 at −1.0 V versus reversible hydrogen electrode, much higher than its counterparts without the hierarchically ordered structure or P‐functionalization. [ABSTRACT FROM AUTHOR]

This article is the sixth and last of a series devoted to the primary structure of bovine β-casein [1–5]. In the preceding paper, we presented a partial sequence of this protein in which 156 out of the 209 amino-acid residues were exactly positioned [5]. Only a few data were given on the tryptic peptides T2 and T3 [1] which corresponded to the unknown part of the molecule. In the present communication, we establish the amino-acid sequence of these 2 peptides, and discuss the salient features of the β-casein molecule. Bovine β-casein A2 is a phosphoprotein constituted of a single polypeptide chain containing 209 amino-acid residues. Among them are five phosphoseryl residues. From sequence data, it can be written: Asp4, Asn5, Thr9, Ser11, SerP5, Glu17, Gln22, Pro35, Gly5, Ala5, Val19, Met6, Ile10, Leu22, Tyr4, Phe9, Trp, Lys11, His5, Arg4. Its exact molecular weight is 23982, a little higher than that of αs1-casein, which is 23616 [6]. The total number of 27 amide groups (Asn + Gln) agrees well with previous data obtained by Pion et al. [7] and Peterson et al. [8]. The average hydrophobicity, calculated according to Bigelow [9], is 1330 and it places β-casein among the most hydrophobic proteins. The sequence obtained emphasizes the uneven charge distribution along the peptide chain. A high negative net charge is located in the first 50 residues. The high proline residue content (16.7%) and the rather uniform repartition of this residue exclude the possibility of a high α-helix content. Furthermore, the complete absence of segments containing more than 2 adjacent prolyl residues seems to preclude the possibility of poly-L-proline structure that was expected from optical-rotatory-dispersion studies [10]. An interesting extension of the present work is the discovery by Gordon et al [11] that γ-, TS-, R- and S-caseins are fragments of β-casein likely originating from tryptic-like cleavages of the peptide chain next to the carbonyl groups of some lysyl residues. The γ-, TS. A2- and S-, TS. B- and R-caseins respectively represent residues 29 to 209, 106 to 209 and 108 to 209. These results explain the occurrence of only one phosphorus atom in the γ-caseins, the absence of phosphorus in the TS-, R- and S-caseins [12]. Localization of the substitutions which differentiate the known variants of bovine β-casein also explains the relationship between β-, γ-, R-, S- and TS-caseins [12,13]. The NH2-terminal tryptic phosphopeptide, previously analyzed by Peterson et al. [14], has been sequenced independently by Manson and Annan [15]. Their results are identical to those reported in a preceding paper [4]. [ABSTRACT FROM AUTHOR]

Previous reports [1-5], we have described some of the features of the primary structure of bovine αs1-casein. In the present work, the complete amino acid sequence has been established and the salient features of this phosphoprotein have been discussed. In the polyeptide chain, the region containing the phosphopeptides Tm1 (T1-T2), Tm1T2 and Tm1T1 [1,4,5], had only been slightly studied as yet. Because of the difficulties encountered in the breakdown of these phosphopeptides, hydrolysis with endopeptidases and exopeptidases were performed on both native and dephosphorylated peptides. It was confirmed that peptide Tm1T2 contains three hydroxy-amino acids (2 Ser, 1 Thr), but, instead of three [1], two phosphorus atoms were found with purified preparations. Partial acid hydrolysis and dephosphorylation using an orthophosphoric-monoester phosphohydrolase indicate that the two seryl residues m this peptide are O-phosphorylated. The remaining gap in the sequence of the central part of peptide Tm1T2 was bridged by studying two fragments obtained by papain digestion of the dephosphorylated preparation. Instead of four serines, postulated earlier from the results of the amino-acid composition of peptide Tm1T1 [1], five were shown to be present after detailed analysis of the fragments. Since the five phosphate groups could be ready removed by an orthophosphoric-monoester phosphohydrolase, the five seryl residues could be O-phosphorylated. The fragments obtained after hydrolysis with thermolysin of both native and dephosphorylated peptide Tra1T1 were further degraded using classical methods for the determination of the amino acid sequence. In the light of all the results obtained on this phosphoprotein (αs1-casein B), the total number of amino acid residues has been corrected to 199, instead of 198, as reported previously [1-5], and the molecular weight has been calculated to be 23616. The following amino-acid composition; Asp7, Asn8, Thr5, Ser8, SerP8, Glu25, Gln14, Pro17, Gly9, Ala9, Val11, Met5, Ile11, Leu17, Tyr10, Phe8, Lys14, His5, Trp2, Arg6, indicates that there is a higher number of acidic than basic residues in this protein. On the basis of the intrinsic dissociation constants of titratable groups in proteins [6], the negative net charge of the molecule was estimated to be 22 at pH 6.5 and 28 at pH 8.6. Since Bigelow's parameter for thc average hydrophobicity [7] of this protein is 1170, it could be considered to be a hydrophobic protein The high amount (8.5%) and uniform distribution of prolyl residues indicate that this protein has limited structuralcoiling possibilities. The polypeptide chain contains three hydrophobic regions, viz. 1-44, 90-113 and 132-199. The first two are characterized by the fact that basic residues predominate over acidic residues. The third region, where most of the aromatic residues are located, contains very few basic residues and is therefore of more acidic character. Two regions, 45-89 and 114-131, are hydrophilic. The former contains more than half of the total acidic residues, in particular seven of the total eight phosphoseryl residues. Another remarkable feature is the concentration of amino acids with carboxylic side chains, particularly glutamic acid, in the vicinity of two clusters of phosphoseryl residues. It may be noticed that the phosphoseryl residues m αs1-casein are arranged m a manner similar to those in β-casein [8]. In particular, in αs1-casein, the 62-70 region containing four phosphoseryl residues, is similar to the 13-21 region in β-casein [8]. It is interesting to point out that ail but one of the phosphoseryl residues always occur m position n with relation to a glutamyl or a phosphoseryl residue, which is in position n + 2. From this, it would appear that there is an enzymatic phosphorylation of the polypeptide chum (carried out by a phosphoryl kinase which may require a negative charge in the phosphorylation site) rather than a direct incorporation of phosphoserine into the polypeptide chain during protein synthesis. The location of the amino-acid substitutions that characterize the αs1-Casein D and the β-casein C variants has provided evidence for an enzymatic phosphorylation of casein [9]. The problem of the phosphorylated sites in αs1- and β-caseins will be discussed in a forthcoming paper. The repeating amino-acid sequences located in the two regions of αs1-casein, viz. 70-84 and 110-125, are also of interest. The primary structure of αs1-casein given here is that of the genetic variant B. The three other variants A, C and D have also been studied. The C and D variants differ from the B variant by the substitutions of Gly/Glu in position 192 [10] and ThrP/Ala in position 53 [9], respectively. The A variant is characterized by a deletion of thirteen amino-acid residues from position 14 to position 26 in the hydrophobic NH2-terminal part of the polypeptide chain [11]. Because of this deletion, there m an important change in the physico-chemical properties of αs1-casein [12, 13]. Some important features of the amino-acid-sequence determination should be noted. Firstly, the great value of maleic anhydride as a reversible-blocking reagent for amino groups of proteins [14], and the usefulness of thermolysin as a specific enzyme for degrading polypeptides [15]. Secondly, the difficulties encountered during the study of the phosphopeptides: these peptides were difficult to purify since they have similar anionic characters and only react slightly with ninhydrin during paper revelation; other difficulties have been the high destruction of phosphoserine during hydrolysis with HCl 5.7 N, the poor yield in the substractive Edman degradation when the NH2-terminal residue is a phosphoserine, and the failure of endopeptidases and exopeptidases to split off peptide bonds that are close to phosphate groups. Fortunately, alkaline phosphatase has proved to be a useful tool for removing phosphate groups, thus avoiding most of these difficulties. Since the amino-acid sequence of αs1-casein is now known, the degradation of this protein by coagulating and other proteolytic enzymes during cheese ripening may be studied. In particular, bitter peptides originating from αs1-casein may be located. As we have already briefly noted [4], it is obvious that one of the three bitter peptides isolated by Matoba et al. [16] from a tryptic hydrolysate of whole casein, was the segment 23-34 of the polypeptide chain of αs1-casein. In addition, the knowledge of the primary structure will be of help in understanding many aspects of the relations between structure and physical properties in this phosphoprotein. [ABSTRACT FROM AUTHOR]

This paper deals with the specific interaction of the dispersant 3,6,9-trioxadecanoic acid (TODA) with nano-ZrO2 surfaces. Special interest was directed towards degradation behavior of the adsorbates and its influence on dispersant capabilities of TODA regarding stabilization of ethanolic nano-ZrO2 suspensions. ZrO2 adsorption sites and the adsorbates formed are examined by diffuse reflectance infrared Fourier transform spectroscopy, thermal analysis, 1H-, and 13C-cross polarization magic angle spinning solid-state nuclear magnetic resonance spectroscopy. 1H as well as 13C-chemical shifts and the configurations of the corresponding adsorbed TODA species on zirconia sites are predicted by means of density functional theory quantum chemical calculations for supporting the interpretation of the experimental spectral data obtained. This work shows that combination of analytical and theoretical methods is an effective approach characterizing surface chemical properties of ceramic materials, determining sorption properties of organic process additives, investigating correspondent elementary and degradation reactions as well as clarifying cause-effect relationships in ceramic processes. [ABSTRACT FROM AUTHOR]

Direct methods have been applied to the SIR (single isomorphous replacement) case to estimate structure-factor moduli from diffraction magnitudes. The joint probability distribution function P(EH, Ep, E,d) has been calculated by explicitly considering, as an additional primitive random variable, the cumulative error arising from measurements and from lack of isomorphism. The specific feature of the approach is that it provides estimated values of EH which depend on the experimental diffraction data as well as on errors. Some test structures have been used to check the efficiency of the new estimates. Patterson techniques, using the estimated EH² values as coefficients, as well as a tangent procedure, have been implemented into a computer program to locate the heavy atoms automatically. All the experimental tests show that the new approach provides results highly competitive with the traditional EH² estimates. [ABSTRACT FROM AUTHOR]

The differences between two databases describing the polypeptide main chain in terms of charge-density parameters, directly usable in protein structure refinements, are discussed. These databases contain averaged multipole populations of peptide pseudo-atoms obtained from refinement against theoretical simulated data and against high-resolution experimental data on small peptide or amino acid molecules. The main discrepancy becomes apparent when electrostatic properties are calculated. [ABSTRACT FROM AUTHOR]

The symmetry-mode analysis of a structural phase transition involves the use of methods of the representation theory of space groups. The aim of the paper is to present an alternative approach for the determination of the primary and secondary symmetry modes that contribute to the structural distortion of the low-symmetry, phase. It only requires the systematic use of the data from International Tables for Crystallography, Vol. A. and is based on a fact. well known to crystallographers: the fully symmetrical displacements of any orbit of atoms (i.e. the modes compatible with the symmetry of the structure) follow in a straightforward way from the coordinate triplets of the corresponding Wyckoff positions. This property, systematically used for all intermediate subgroups between the space groups of the two phases, allows the determination of the relevant symmetry modes. Their distraction into primary, and secondary modes comes out directly in the process of calculation. As an example, primary and secondary modes m the ferroelectric distortion of potassium selenate are divided. [ABSTRACT FROM AUTHOR]

The phosphorothioate analog of ATP has a sulfur atom replacing a non-bridging oxygen atom of the triphosphate moiety of ATP. Due to the tetrahedral nature of the phosphorus atom, stereoisomers are known to exist, designated as the Sp and Rp isomers. We have reported [Shimizu & Furusawa (1986) Biochemistry 25, 5787] on the hydrolytic activity of the 22S dynein from Tetrahymema cilia towards the phosphorothioate analogs of ATP. In this paper, we extend our study and report on the microtubule-dynein dissociation by these analogs and on their ability to support sea urchin flagellar dynein enzymatic activity as well as ciliary or flagellar motility. It has been shown that the microtubules — 22s-dyein complex is dissociated by the binding of ATP to the enzymatic sites [Porter & Johnson (1983) J. Biol. Chem. 258, 6575]. We studied the dissociation by adenosine 5’-[α-thio]triphosphate (ATP[αS]), Sp and Rp, by light-scattering stopped-flow methods. The dissociation by (Sp)ATP[αS] was rapid and the rate of the light-scattering change by (Sp)ATP[αS] was a hyperbolic function of the nucleotide concentration, indicating that dissociation was a two-step process. On the other hand, (Rp )ATP[αS] up to 2 mM induced only slow and partial dissociation of the complex, while, in the presence of vanadate, it induced complete dissociation with a slightly higher rate (0.5 s-1). The adenosine 5’-[β-thio]triphosphate (ATP[βS]) isomers did not induce dissociation. The hydrolytic activity of the outer arm dyein from sea urchin sperm flagella towards these analogs was similar to that of 22S dynein. The ratios of Vmax (nmol · mg protein-1 · min-1)/apparent Km (µM) of this dynein were 400-720, 53, 9.7, 0.62 and 0.028 for ATP, ATP[αS] (Sp or Rp), ATP[βS] (Sp or Rp), respectively, in the presence of Mg2+ as the supporting cation. This dynein exhibited the same stereospecificity at β phosphate as the 22S dynein or myosin. The detergent models of Tetrahymena or sea urchin spermatozoa were reactivated only by ATP or (Sp)ATP[αS] while other analogs were ineffective. The maximal beat frequency of the cilia or flagella reactivated by (Sp)ATP[αS] was one‐quarter to one‐half of that produced by ATP reactivation. [ABSTRACT FROM AUTHOR]

Honeycomb‐layered oxides with monovalent or divalent, monolayered cationic lattices generally exhibit myriad crystalline features encompassing rich electrochemistry, geometries, and disorders, which particularly places them as attractive material candidates for next‐generation energy storage applications. Herein, global honeycomb‐layered oxide compositions, Ag2M2TeO6 (M=Ni,Mg,etc$M = \rm Ni, Mg, etc$.) exhibiting Ag$\rm Ag$ atom bilayers with sub‐valent states within Ag‐rich crystalline domains of Ag6M2TeO6 and Ag$\rm Ag$‐deficient domains of Ag2−xNi2TeO6${\rm Ag}_{2 - x}\rm Ni_2TeO_6$ (0

Cobalt single atoms coordinated with planar four nitrogen atoms (Co1N4) represent an efficient electrocatalyst for oxygen evolution reaction (OER), whereas the large energy barrier of CoOH dehydrogenation limits the OER activity. Herein, axial phosphate (PO4) coordination is incorporated in Co1N4 single atoms of cobalt phthalocyanine@carbon nanotubes (P‐CoPc@CNT), so as to boost the intrinsic OER performance through manipulating the reaction pathway. With a relative low mass loading of Co (2.7%), the P‐CoPc@CNT shows remarkable alkaline OER activity with the overpotential of 300 mV and Tafel slope of 41.7 mV dec−1, which dramatically outperforms the CoPc@CNT without axial PO4 coordination. Based on mechanistic analysis, the axial PO4 coordination directly participates in the OER cycle by the transformation of axial ligand. Specially, the CoOH dehydrogenation process is replaced by the dehydrogenation of HPO4‐Co1N4 intermediate, which largely decreases the energy barrier and thus benefits the whole OER process. [ABSTRACT FROM AUTHOR]

Reversible‐deactivation radical polymerizations (RDRPs) have revolutionized synthetic polymer chemistry. Nowadays, RDRPs facilitate design and preparation of materials with controlled architecture, composition, and functionality. Atom transfer radical polymerization (ATRP) has evolved beyond traditional polymer field, enabling synthesis of organic–inorganic hybrids, bioconjugates, advanced polymers for electronics, energy, and environmentally relevant polymeric materials for broad applications in various fields. This review focuses on the relation between ATRP technology and the 12 principles of green chemistry, which are paramount guidelines in sustainable research and implementation. The green features of ATRP are presented, discussing the environmental and/or health issues and the challenges that remain to be overcome. Key discoveries and recent developments in green ATRP are highlighted, while providing a perspective for future opportunities in this area. [ABSTRACT FROM AUTHOR]

The new phase Be3Ru crystallizes with TiCu3‐type structure (space group Pmmn (59), a=3.7062(1) Å, b=4.5353(1) Å, c=4.4170(1) Å), a coloring variant of the hexagonal closest packing (hcp) of spheres. The electronic structure revealed that Be3Ru has a pseudo‐gap close to the Fermi level. A strong charge transfer from Be to Ru was observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework and polar three‐ and four‐atomic Be−Ru bonds were observed from the ELI−D (electron localizability indicator) analysis. This situation is very similar to the recently investigated Be5Pt and Be21Pt5 compounds. The unusual crystal chemical feature of Be3Ru is that different charged species belong to the same closest packing, contrary to typical inorganic compounds, where the cationic components are located in the voids of the closest packing formed by anions. Be3Ru is a diamagnet displaying metallic electrical resistivity. [ABSTRACT FROM AUTHOR]

The different coordination behavior of the flexible yet sterically demanding, hemilabile P,N ligand bis(quinoline‐2‐ylmethyl)phenylphosphine (bqmpp) towards selected CuI, AgI and AuI species is described. The resulting X‐ray crystal structures reveal interesting coordination geometries. With [Cu(MeCN)4]BF4, compound 1 [Cu2(bqmpp)2](BF4)2 is obtained, wherein the copper(I) atoms display a distorted square planar and square pyramidal geometry. The steric demand and π‐stacking of the ligand allow for a short Cu⋅⋅⋅Cu distance (2.588(9) Å). CuI complex 2 [Cu4Cl3(bqmpp)2]BF4 contains a rarely observed Cu4Cl3 cluster, probably enabled by dichloromethane as the chloride source. In the cluster, even shorter Cu⋅⋅⋅Cu distances (2.447(1) Å) are present. The reaction of Ag[SbF6] with the ligand leads to a dinuclear compound (3) in solution as confirmed by 31P{1H} NMR spectroscopy. During crystallization, instead of the expected phosphine complex 3, a tris(quinoline‐2‐ylmethyl)bisphenyl‐phosphine (tqmbp) compound [Ag2(tqmbp)2](SbF6)24 is formed by elimination of quinaldine. The Au(I) compound [Au2(bqmpp)2]PF6 (5) is prepared as expected and shows a linear arrangement of two phosphine ligands around AuI. [ABSTRACT FROM AUTHOR]

A `one-step' theory based on Pitsch distortion is proposed to explain the continuity between the orientations of the Kurdjumov-Sachs (KS), Nishiyama-Wassermann (NW) and Pitsch variants observed on the electron backscatter diffraction pole figures of martensitic alloys. The Pitsch distortion respects the hard-sphere packing of the iron atoms and implies the existence of a neutral line along the close-packed direction [110]γ = [111]α. Its principal strains are 0, −5.7 and 15.5%, well below the +12, +12 and −20% values of the Bain distortion. At the nucleation step, the distortion generates martensite that continuously deforms the austenitic matrix. Martensite continues to grow in Pitsch orientation inside the deformation field of the surrounding austenite to reach KS and NW orientations in reference to the bulk austenite. Some experimental results reported in the literature are revisited, such as the {225}γ habit planes, the sometimes observed `twins' at the midrib, the formation of butterfly martensite, and the effect of prior plastic deformation of austenite on the transformation temperature and on variant selection mechanisms. [ABSTRACT FROM AUTHOR]

A new study of the σ A parameter has been undertaken to understand its behaviour when the diffraction amplitude distributions are far from the standard Wilson distributions. The study has led to the formulation of a new statistical interpretation of σ A, expressed in terms of a correlation factor. The new formulas allow a more accurate use of σ A in electron-density modification procedures. [ABSTRACT FROM AUTHOR]

The generalized multicomponent short-range order (GM-SRO) parameter has been adapted for the characterization of short-range order within the highly chemically and spatially resolved three-dimensional atomistic images provided by the microscopy technique of atom-probe tomography (APT). It is demonstrated that, despite the experimental limitations of APT, in many cases the GM-SRO results derived from APT data can provide a highly representative description of the atomic scale chemical arrangement in the original specimen. Further, based upon a target set of the GM-SRO parameters, measured from APT experiments, a Monte Carlo algorithm was utilized to simulate statistically equivalent atomistic systems which, unlike APT data, are complete and lattice based. The simulations replicate solute structures that are statistically consistent with other correlation measures such as solute cluster distributions, enable more quantitative characterization of nanostructural phenomena in the original specimen and, significantly, can be incorporated directly into other models and simulations. [ABSTRACT FROM AUTHOR]

The rigid-bond model [Hirshfeld (1976). Acta Cryst. A 32, 239-244] states that the mean-square displacements of two atoms are equal in the direction of the bond joining them. This criterion is widely used for verification (as intended by Hirshfeld) and also as a restraint in structure refinement as suggested by Rollett [ Crystallographic Computing (1970), edited by F. R. Ahmed et al., pp. 167-181. Copenhagen: Munksgaard]. By reformulating this condition, so that the relative motion of the two atoms is required to be perpendicular to the bond, the number of restraints that can be applied per anisotropic atom is increased from about one to about three. Application of this condition to 1,3-distances in addition to the 1,2-distances means that on average just over six restraints can be applied to the six anisotropic displacement parameters of each atom. This concept is tested against very high resolution data of a small peptide and employed as a restraint for protein refinement at more modest resolution ( e.g. 1.7 Å). [ABSTRACT FROM AUTHOR]

The topological complexity of a crystal structure can be quantitatively evaluated using complexity measures of its quotient graph, which is defined as a projection of a periodic network of atoms and bonds onto a finite graph. The Shannon information-based measures of complexity such as topological information content, IG, and information content of the vertex-degree distribution of a quotient graph, Ivd, are shown to be efficient for comparison of the topological complexity of polymorphs and chemically related structures. The IG measure is sensitive to the symmetry of the structure, whereas the Ivd measure better describes the complexity of the bonding network. [ABSTRACT FROM AUTHOR]

Polysynthetic Brazil twinning in α-quartz, which occurs commonly in amethyst, is interpreted in the literature as having its composition planes parallel to one of the faces of the major rhombohedron r. It is shown that, instead, the composition planes are parallel to one of the faces of the minor rhombohedron z. The proposed translation 0.4547 a between neighbouring lamellae leads to binding distances and binding angles across the composition plane that differ less from their bulk values than for the translation 0.5 a proposed in the literature. Density functional calculations show that the energy of the unrelaxed polysynthetic twin is lower for the proposed translation. They also show that relaxation increases the thickness of the polytwin by 4 pm per composition plane. [ABSTRACT FROM AUTHOR]

This paper deals with the specific interaction of the dispersant 3,6,9-trioxadecanoic acid (TODA) with nano-ZrO2 surfaces. Special interest was directed towards degradation behavior of the adsorbates and its influence on dispersant capabilities of TODA regarding stabilization of ethanolic nano-ZrO2 suspensions. ZrO2 adsorption sites and the adsorbates formed are examined by diffuse reflectance infrared Fourier transform spectroscopy, thermal analysis, 1H-, and 13C-cross polarization magic angle spinning solid-state nuclear magnetic resonance spectroscopy. 1H as well as 13C-chemical shifts and the configurations of the corresponding adsorbed TODA species on zirconia sites are predicted by means of density functional theory quantum chemical calculations for supporting the interpretation of the experimental spectral data obtained. This work shows that combination of analytical and theoretical methods is an effective approach characterizing surface chemical properties of ceramic materials, determining sorption properties of organic process additives, investigating correspondent elementary and degradation reactions as well as clarifying cause-effect relationships in ceramic processes. [ABSTRACT FROM AUTHOR]

A simple tensorial contraction method has been developed to obtain analytical formulae for X-ray resonant magnetic scattering. First, the method has been applied considering electric dipole–dipole and electric quadrupole–quadrupole scattering in the isolated-atom approximation. The results have been compared with previous work. The same method has then been extended to non-spherical systems by deriving new phenomenological formulae. [ABSTRACT FROM AUTHOR]

For non-centrosymmetric structures in space group P1 containing a centrosymmetric substructure, analytical expressions have been obtained for various functions of the diffraction intensity of Friedel opposites. These functions are the average intensity of Friedel opposites, the mean difference in intensity of Friedel opposites and the mean-square difference in intensity of Friedel opposites. A Bijvoet intensity ratio is defined for the evaluation of resonant-scattering effects in non-centrosymmetric and pseudo-centrosymmetric structures. Analysis of these expressions confirms that both resonant and non-resonant atoms are necessary to produce differences in intensity between Friedel opposites and also shows that in some circumstances atoms may lie on a centrosymmetric substructure without diminishing the Bijvoet intensity ratio. The effects of the real component of resonant scattering, of the variation of the scattering factors with sin θ/λ, of isotropic atomic displacement parameters, of a crystal twinned by inversion, of atoms in special positions and of weak reflections are considered. Software is available for the evaluation of the Bijvoet intensity ratio. [ABSTRACT FROM AUTHOR]

The determination of molecular absolute configuration from an X-ray analysis for structures that contain only light elements is challenging owing to the weak anomalous dispersion signal. The achievable precision of the Flack x parameter for such structures is therefore limited, especially when the independent-atom model is employed. Invariom modelling can improve this situation. Invarioms are theoretically predicted pseudoatoms within the Hansen & Coppens multipole formalism. They are transferable from one molecule to another and provide generalized aspherical atomic form factors. It is shown that, by application of the invariom approach, the precision and standard uncertainty of the Flack x parameter and therefore the reliability of deducing molecular chirality in an absolute structure determination can be improved. [ABSTRACT FROM AUTHOR]

It is shown that the locus of the f′ + if′′ plot in the complex plane, f′ being determined from measured f′′ by using the dispersion relation, looks like a semicircle very near the absorption edge of Ge. The semicircular locus is derived from a quantum theory of X-ray resonant scattering when there is a sharp isolated peak in f′′ just above the K-absorption edge. Using the semicircular behavior, an approach is proposed to determine the anomalous scattering factors in a crystal by fitting known calculated values based on an isolated-atom model to a semicircular focus. The determined anomalous scattering factors f′ show excellent agreement with the measured values just below the absorption edge. In addition, the phase determination of a crystal structure factor has been considered by using the semicircular behavior. [ABSTRACT FROM AUTHOR]

For more than forty years, the experimental determination and analysis of electron densities have played a fundamental role in advances in the chemical bond concept. The present paper illustrates the application of this approach to the field of molecular magnetism with examples that recently appeared in the literature. Particular attention is attached to several classes of materials, purely organic free radicals, coordination compounds and organometallic complexes, which exhibit specific magnetic behaviors. It is shown to what extent the electron-density analysis can shed light on bonding aspects that are closely related to magnetic couplings. Relations between spin delocalization, spin polarization, superexchange and the characteristics of the electron density are described. The use of the topological theory of 'atoms in molecules' allows the possible magnetic interaction pathways to be located and defined, especially through weak intermolecular contacts. The complementarity with polarized neutron diffraction and spin-density modeling techniques is particularly evident from the chosen examples. [ABSTRACT FROM AUTHOR]

This work introduces a local form for the source function, from each atom, for the electron-density value at a given point. The source function enables one to equate the value of the electron density at any point within a molecule to a sum of atomic contributions and thus to view properties of the density at representative points, such as the bond critical points, from a new perspective. The local form of the function introduces further detail. When plotted along a bond path and with reference to the bond critical point (b.c.p.), the source function shows which regions of .the atoms involved in the bonding are accumulating or removing electronic charge at the b.c.p. The local form of the source function therefore represents an interesting fingerprint of a given bonding interaction. The local source may be expressed as a sum of two contributions, related to the kinetic energy density and electronic potential energy density, respectively. This approach gives further physical insight into why an atomic region is accumulating or removing charge at the b.c.p. The local form of the source function is applied to the study of the second-row diatomic hydride series and of a number of prototypical hydrogen-bonded systems. Differences in the local source contributions to the density at bond critical points due to chemical bonding (deformation density) and crystallization (interaction density) are also explored and found to be more informative and experimentally detectable than are the corresponding changes for the bondcritical-point properties of weak intermolecular interactions. This result might be of potential interest when judging the data quality of a charge-density experimental determination. Although the present paper deals with electron densities derived from theoretical computations only, both the source function and its local form should also be easily obtainable from a charge-density quality X-ray diffraction experiment. [ABSTRACT FROM AUTHOR]

In U4O9, most of the atoms are in general 48-fold [48(e)] sites of the space group I&4macr;3d and yet the hkl reflections obey the extinction rules for atoms occupying special 12-fold [12(b)] sites. An explanation is given for this effect, which can be generalized to any space group. [ABSTRACT FROM AUTHOR]

Relations between direct and reciprocal basis vectors and the atomic displacement matrix and anisotropic temperature-factor matrix are provided for generic dimension n, introducing a few new symbols. The moments of the probability distribution of the anisotropic thermal ellipsoids are provided as functions of dimension n. For specific dimensions n = 2 and n = 3, new explicit formulas for the semi-axis lengths and rotation angles of the thermal ellipsoids are derived from the atomic displacement matrix, taking into account certain special cases. For dimension n = 3, the Euler angles are defined. The resulting formulas can be used, for example, to display the thermal ellipsoids of atoms or for further analysis of molecular vibrations. [ABSTRACT FROM AUTHOR]

Presents a generalization of the probabilistic theory of the three-phase structure invariants for isomorphous pairs to the case in which a heavy-atom structure model is available. Application of the method of joint probability distributions; Role of Hauptman et al (1982) in the initiation of the probability theory of the three-phase structure invariants.

Identifies the analytical wave functions for neutral atoms and for all chemically important ions. Calculation of numerical relativistic wave functions for all chemically relevant ions; X-ray scattering factors calculated from the numerical wave functions.

Describes the evaluation of net atomic charges and atomic and molecular electrostatic moments through topological analysis of the experimental charge density. Large differences found between charges derived from the monopole parameters and those from atoms in molecules analysis of the experimental model density.

Three coordination polymers based on quaternary‐ammonium‐modified isophthalic acid, namely, catena‐poly[[[aqua‐μ2‐bromido‐di‐μ3‐hydroxido‐methanoldinitratotetracopper(II)]‐bis{μ4‐5‐[2‐(tripropylazaniumyl)ethoxy]benzene‐1,3‐dicarboxylato}] nitrate], {[Cu4Br(C19H28NO5)2(NO3)2(OH)2(CH4O)(H2O)]NO3}n, 1, poly[μ3‐bromido‐μ2‐bromido‐bromido‐μ3‐hydroxido‐{μ4‐5‐[2‐(tripropylazaniumyl)ethoxy]benzene‐1,3‐dicarboxylato}tricopper(II)], [Cu3Br3(C19H28NO5)(OH)]n, 2, and poly[bromido{μ3‐5‐[2‐(tripropylazaniumyl)ethoxy]benzene‐1,3‐dicarboxylato}zinc(II)], [ZnBr(C19H28NO5)]n, 3, were obtained by solvothermal reactions. Coordination polymer (CP) 1 contains tetranuclear Cu4 units, in which the four Cu atoms are linked by two μ3‐OH− groups into a Cu4(OH)2 cluster, which are in turn linked by 5‐[2‐(tripropylazaniumyl)ethoxy]benzene‐1,3‐dicarboxylate (cpa−) ligands into a chain structure. CP 2 also contains a tetranuclear Cu4(OH)2 cluster and these are linked with CuBr3 units into chains. The chains are then connected by cpa− ligands into a two‐dimensional layered structure. CP 3 contains a two‐dimensional layer structure built by binuclear Zn2 units and cpa− ligands. The Br− counter‐anions of the quaternary ammonium groups all take part in the construction of the polymeric networks. [ABSTRACT FROM AUTHOR]

Discusses the nomenclature of steroids. Stereochemistry of the side chain; Omission of steroid alkaloid and steroid-like triterpenoids; Definition of sterols; Bonds of atoms.

Energetic neutral atoms (ENAs) created by charge‐exchange of ions with the Earth's hydrogen exosphere near the subsolar magnetopause yield information on the distribution of plasma in the outer magnetosphere and magnetosheath. ENA observations from the Interstellar Boundary Explorer (IBEX) are used to image magnetosheath plasma and, for the first time, low‐energy magnetospheric plasma near the magnetopause. These images show that magnetosheath plasma is distributed fairly evenly near the subsolar magnetopause; however, low‐energy magnetospheric plasma is not distributed evenly in the outer magnetosphere. Simultaneous images and in situ observations from the Magnetospheric Multiscale (MMS) spacecraft from November 2015 (during the solar cycle declining phase) are used to derive the exospheric density. The ~11–17 cm−3 density at 10 RE is similar to that obtained previously for solar minimum. Thus, these combined results indicate that the exospheric density 10 RE from the Earth may have a weak dependence on solar cycle. Key Points: ENA cameras image both magnetosheath and magnetospheric plasmas in the vicinity of the subsolar magnetopauseMagnetospheric plasma is not distributed evenly across the dayside near the magnetopauseThe exospheric hydrogen density near the magnetopause may have a weak dependence on solar F10.7 [ABSTRACT FROM AUTHOR]

The crystal structure of the polymeric title complex, [CuCl2(C3H6N4)] n, has been solved from laboratory X-ray powder diffraction data collected at room temperature. The structural model obtained was refined with the Rietveld method using geometric soft restraints. There are two Cu atoms, two Cl atoms and one 1,5-dimethyl­tetra­zole ligand in the asymmetric unit. Both Cu atoms lie on inversion centres and adopt essentially elongated octa­hedral coordination. Within the octa­hedra, the elongated axial positions are occupied by Cl atoms, while two Cl and two N atoms (N3 and N4 of the tetra­zole ring) are in equatorial sites. Each Cl atom forms an asymmetric bridge between neighbouring Cu atoms, which are also bridged via the N3—N4 bond of the tetra­zole ring. These bridges result in the formation of polymeric chains, running along the a axis, with weak C—H⋯Cl hydrogen bonds crosslinking the chains. [ABSTRACT FROM AUTHOR]

The title compound, [Cd(C6H4NO2)2(H2O)2]n, forms a one-dimensional chain structure based on a Cd atom with approximate pentagonal bipyramidal coordination geometry and two nicotinate ligands in different coordination modes. One acts as a tridentate ligand, chelating one Cd atom through the carboxylate group while simultaneously binding to a second symmetry-related Cd atom through the pyridine N atom; the other acts only as a bidentate ligand through its carboxylate group. Hydrogen bonds utilizing the coordinated water molecules, uncoordinated nitrogen and carboxylate O atoms as acceptors link the chains. [ABSTRACT FROM AUTHOR]

Four differently substituted chiral Ni(II)-complexes of dehydroalanine Schiff base were prepared and reacted with BrCF2COOEt/Cu under the standard reaction conditions. The observed diastereoselectivity was found to depend on the degree and pattern of chlorine substitution for hydrogen in the structure of the dehydroalanine complexes. The unsubstituted complex gave the ratio of diastereomers (S)(2S)/(S)(2R) of 66/34. On the other hand, introduction of chlorine atoms in the strategic positions on the chiral ligands allowed to achieve a practically attractive diastereoselectivity of (~ 98.5/1.5). Diastereomerically pure major product was disassembled to prepare 9-fluorenylmethyloxycarbonyl (Fmoc) derivative of (S)-4,4-difluoroglutamic acid. [ABSTRACT FROM AUTHOR]