In the present study, microseed matrix seeding was successfully applied to obtain a large number of crystals of the human sirtuin isotypes Sirt2 and Sirt3. These crystals appeared predictably in diverse crystallization conditions, diffracted to a higher resolution than reported in the literature and were subsequently used to study the protein–ligand interactions of two indole inhibitors. +-dependent enzymes that catalyse the cleavage of various acyl groups from the ∊-amino group of lysines. They regulate a series of cellular processes and their misregulation has been implicated in various diseases, making sirtuins attractive drug targets. To date, only a few sirtuin modulators have been reported that are suitable for cellular research and their development has been hampered by a lack of structural information. In this work, microseed matrix seeding (MMS) was used to obtain crystals of human Sirt3 in its apo form and of human Sirt2 in complex with ADP ribose (ADPR). Crystal formation using MMS was predictable, less error-prone and yielded a higher number of crystals per drop than using conventional crystallization screening methods. The crystals were used to solve the crystal structures of apo Sirt3 and of Sirt2 in complex with ADPR at an improved resolution, as well as the crystal structures of Sirt2 in complex with ADPR and the indoles EX527 and CHIC35. These Sirt2–ADPR–indole complexes unexpectedly contain two indole molecules and provide novel insights into selective Sirt2 inhibition. The MMS approach for Sirt2 and Sirt3 may be used as the basis for structure-based optimization of Sirt2/3 inhibitors in the future.Sirtuins constitute a family of NAD The crystal structures of the deacylase domain of all sirtuin isotypes except Sirt4 and Sirt7 in differently ligated states have been solved to date . The two domains are separated by a large cleft that constitutes the catalytic core. Both domains are connected via a series of loops that play important roles during cofactor binding, acyl-lysine binding and the ‘open-to-closed’ rotation. During catalysis, NAD+ adopts a kinked conformation which brings the C1′ of its ribose moiety into proximity for a nucleophilic attack by the carbonyl O atom of the acetyl lysine that is inserted in a hydrophobic tunnel . On cleavage of nicotinamide and the formation of an alkylimidate complex, the acetyl group is transferred via several intermediates from the ∊-amino group to the ADP ribose (ADPR) moiety, generating 2′-O-acetyl-ADPR and releasing the deacetylated lysine. Deacylation is thought to proceed in a similar fashion  in diverse crystallization conditions. Using MMS, crystal formation was predictable, less error-prone and yielded a large number of crystals. The crystals were used to obtain crystal structures of Sirt2 in complex with ADPR and of apo Sirt3 at an improved resolution. They also proved to be perfectly suited for the investigation of protein–ligand interactions and were subsequently used to solve two novel crystal structures of Sirt2 in complex with ADPR and indole inhibitors. Both Sirt2–ADPR–indole complexes unexpectedly contained two inhibitor molecules in the active site of Sirt2, highlighting the specific characteristics of Sirt2 within the sirtuin family.2.2.1.10 tag instead of a His6 tag and a TEV protease cleavage site instead of a thrombin cleavage site. Human Sirt250–356, Sirt256–356 and Sirt3118–395 were expressed in Escherichia coli strain BL21(DE3) CodonPlus RIPL cells overnight (20°C for Sirt2 and 18°C for Sirt3). Overexpression was induced with IPTG (0.1 mM) at an OD600 of 0.6. The cells were harvested and resuspended in lysis buffer . The cells were then lysed with a microfluidizer  and cell debris was removed via centrifugation. The supernatant was applied onto a HisTrap FF column , washed intensively with lysis buffer and then treated with TEV protease (in excess). After overnight digestion (4°C), the digested protein was eluted with lysis buffer, concentrated and further purified with a Superdex S75 26/60 gel-filtration column . Sirt2- or Sirt3-containing fractions were collected and concentrated to 20 mg ml−1 in the case of Sirt250–356, 13 mg ml−1 in the case of Sirt256–356 and 18.5 mg ml−1 in the case of Sirt3. All purification steps were monitored by SDS–PAGE  and human Sirt3  were cloned in a modified pET-15b vector with a His2.2.http://hamptonresearch.com/documents/product/hr005585_2-134_formulations.pdf. Crystal formation was monitored with a Minstrel HT UV imaging unit . Initial crystals that were used for MMS of apo Sirt3 (18.5 mg ml−1) were obtained in a solution consisting of 0.2 M Li2SO4, 60%(v/v) Tacsimate (Hampton Research) at pH 7.0 and 4°C with a 1:1 ratio of Sirt3 solution to reservoir solution. Initial crystals of the Sirt256–356–ADPR complex  were obtained in a solution consisting of 17.5%(w/v) PEG 10 000, 0.1 M ammonium acetate in 0.1 M bis-tris buffer pH 6.75 at 20°C using a 1:3 ratio of Sirt2–ADPR solution to reservoir solution. Microseed solutions were prepared as follows: 5–10 crystals were harvested, washed, diluted with mother liquor and transferred into an Eppendorf tube, where they were crushed with a seed bead [five cycles of slight vortexing (10 s) followed by incubation on ice (20 s)]. The supernatant was then used for crystallization trials. For crystallization trials using microseed solutions the drop consisted of 17%(v/v) microseed solution, 50–33%(v/v) Sirt3 solution (18.5 mg ml−1) or Sirt2–ADPR solution  and 33–50%(v/v) reservoir solution. Control experiments to verify that Sirt3 crystal formation was dependent on microseeds were performed with the mother liquor only .All crystallization trials were performed in 96-well plates  using an OryxNano pipetting robot . Index screen was obtained from Hampton Research . The composition of the crystallization solutions in the Index screen can be found at 50–356 in complex with ADPR  were obtained in a solution consisting of 30%(w/v) PEG 3350, 0.2 M NaCl in 0.1 M bis-tris buffer pH 6.25 at 4°C. The crystals formed after 3–4 d and were mounted on nylon loops before flash-cooling in liquid nitrogen. Apo Sirt3 crystals were obtained by MMS in a solution consisting of 25%(w/v) PEG 3350, 0.2 M MgCl2 in 0.1 M bis-tris buffer pH 5.5 at 4°C. The crystals were cryoprotected by the addition of PEG 3350 to a final concentration of 30%(w/v) PEG 3350, mounted on nylon loops and flash-cooled in liquid nitrogen.Crystals of Sirt256–356 in complex with ADPR were obtained via MMS in a solution consisting of 18%(w/v) PEG 10 000 in 0.1 M bis-tris buffer pH 5.75 at 20°C. These crystals formed after 1 d and were then soaked in a buffer consisting of 18%(w/v) PEG 10 000, 10%(v/v) DMSO, 0.1 M bis-tris buffer pH 5.75 and either 10 mM EX527  or 10 mM CHIC35 (Sigma–Aldrich) for 30–90 min. The crystals were cryoprotected by the addition of 20%(v/v) glycerol and were then mounted on nylon loops before flash-cooling in liquid nitrogen.For soaking experiments with indole inhibitors, crystals of Sirt22.3.50–356–ADPR) and X06DA (apo Sirt3) at the Swiss Light Source, Villigen, Switzerland using Pilatus detectors  at 100 K with oscillations of 0.2 or 0.5° and an X-ray wavelength of 1.0 Å. Data for Sirt256–356 in complex with ADPR and EX243 and data for Sirt256–356 in complex with ADPR and CHIC35 were collected using a MicroMax-007 HF rotating-anode X-ray generator (Rigaku) at a wavelength of 1.5418 Å equipped with a MAR345 image-plate detector . For each structure, one single crystal was used. Data were processed with MOSFLM  and were placed into 2Fo − Fc electron-density maps using AFITT-CL . All residues of Sirt2 and Sirt3 except those of the flexible N- and C-termini are defined by electron density. In the crystal structures of the Sirt2–ADPR–indole complexes, a methionine and a histidine are seen at the N-terminus. They originate from the NdeI restriction site of the pET vector. All structures were validated using PROCHECK . Iterative-build OMIT electron-density maps for the ligands of all structures as well as the hinge loop of the Sirt2–ADPR complex and the surface of the binding pockets were generated with the PHENIX suite  Tacsimate at 4°C . The epitaxically twinned crystals appeared after one week and diffracted to 2.4–3.0 Å resolution. Further optimization of the crystallization conditions did not improve either the crystal morphology or diffraction. Furthermore, initial soaking experiments failed owing to the insolubility of our drug-like ligands in the highly polar Tacsimate condition. We therefore opted for seeding. The use of microseeds in the Index screen (Hampton Research), as described by D’Arcy et al. (2007c). The best results were obtained with a microseed solution of 1–2 crystals per 10 µl reservoir solution. In most cases, mainly in acidic PEG 3350-containing conditions, apo Sirt3 formed single crystals  predictably within several days. They showed an improved diffraction pattern to a resolution of below 2.0 Å. During the initial crystallization screenings we also found that the presence of lithium sulfate was an important nucleation factor, as the initial crystals could only be obtained in the presence of lithium sulfate. We also investigated the influence of lithium sulfate on the crystallization of apo Sirt3 in the presence of microseeds using the Index screen (Hampton Research). Again, apo Sirt3 crystallized rapidly in diverse conditions, over a wide pH range and at different temperatures within days . In a control experiment, we also performed crystallization trials in a similar fashion with the same seeding solutions but without microseeds. Here, we could only observe crystal formation in two different crystallization conditions (data not shown). The formation of the apo Sirt3 crystals was therefore dependent on the presence of microseeds.Initial crystals of apo Sirt3 were obtained in a solution consisting of 0.2  al. 2007, proved  al. 2007c. The b3.2.et al. . A similar behaviour has also been observed in the published crystal structure of human apo Sirt3  with chain A of the improved structure of Sirt3 shows a high similarity . Similar to the published X-ray structure of apo Sirt3, the acyl-lysine binding site of all monomers is occupied by a PEG molecule. This has also been observed in other sirtuin structures  for crystallization trials of Sirt2. Cross-seeding using microseed solutions of apo Sirt3 failed. However, we succeeded using conventional screening methods and obtained crystals of both Sirt2 forms in complex with ADPR. Initially, Sirt250–356 crystallized in the presence of the cosubstrate NAD+ (2 mM) after a month in Index screen condition F10 (Hampton Research) with a 1:1 ratio of reservoir solution to protein solution at 4°C. This crystallization condition was optimized to 30%(w/v) PEG 3350, 0.2 M NaCl in 0.1 M bis-tris buffer at pH 6.25 and 4°C. Additionally, the NAD+ concentration and the protein:reservoir ratio were increased to 20 mM and 3:1, respectively. Thus, Sirt250–356 crystals appeared within 3–4 d. Using the diffraction data obtained from one of these crystals, we determined the space group as P212121 and were able to solve the structure of Sirt2 by molecular replacement at a resolution of 1.63 Å  that adopt the ‘closed’ sirtuin conformation. In contrast to the recently published structure, we were also able to include all of the residues of one loop of the hinge region (amino acids 136–144) that connects the Rossmann-fold domain to the zinc-binding domain in our model .We used two different truncated forms of Sirt2 . Again, the crystal count and the predictability of crystal formation were better compared with conventional screening methods set up in the absence of microseeds, while the diffraction quality was equally good.However, the handling of the Sirt23.4.et al., 2005et al., 2013a). Both have been widely used to study sirtuins in vivo . The chlorinated hydrophobic indole moiety also extends into another binding pocket adjacent to the C-pocket that has been termed the extended C-site (ECS). In addition to the indole, all sirtuin–indole complexes contain either the cofactor NAD+ or the product analogue ADPR. This is in line with kinetic studies, which concluded that the presence of NAD+ or the product analogue ADPR is essential for binding of the indole inhibitor  with soaking durations of 90 min did not deteriorate the diffraction pattern of the crystals. Using the diffraction data obtained from the soaked crystals, we were able to solve the crystal structures of Sirt2 in complex with ADPR and either EX243  or CHIC35 (Sirt2–ADPR–CHIC35 structure) by molecular replacement. The space group of the soaked crystals was determined to be P212121, similar to the space group of the unsoaked Sirt2–ADPR crystals. The asymmetric unit contains two monomers that show no significant differences [r.m.s.d.s of 0.29 Å (Sirt2–ADPR–EX243) and 0.23 Å (Sirt2–ADPR–CHIC35) for all Cα atoms]. The following descriptions are therefore based on chain A. The Sirt2–ADPR–indole complexes adopt the ‘closed’ conformation and share a very close resemblance to the Sirt2–ADPR structure described in §α atoms; Fig. 4c]. The only significant differences can be observed at the hinge region . Here, the indole inhibitors induce a 6 Å shift of one hinge loop . The ADPR molecules of both structures assume a position that is almost identical to that observed in the Sirt2–ADPR complex. To our surprise, each Sirt2 molecule of both Sirt2–ADPR–indole complexes contains two identical indole molecules in an S-configuration . One molecule occupies the C-pocket as well as the extended C-site, and we will refer to this molecule as the ‘ECS molecule’. The other molecule is found at the hinge region in a pocket that we recently described as the selectivity pocket . The ECS molecule in both Sirt2–ADPR–indole complexes is involved in a network of hydrophilic and hydrophobic interactions with Sirt2, ADPR and two highly coordinated water molecules . The carboxamide of both indole inhibitors binds in a similar fashion as the carboxamide moiety of the physiological inhibitor nicotinamide and hydrogen-bonds to the highly conserved residues Ile169 and Asp170 and, via one of the water molecules (W24 in Sirt2–ADPR–CHIC35 and W206 in Sirt2–ADPR–EX243), to Ala85, Ile93 and Pro94. The amide of the indole hydrogen-bonds to Gln167 and, via the other highly coordinated water (W3 in Sirt2–ADPR–CHIC35 and W203 in Sirt2–ADPR–EX243), to Asp168 and ADPR. The ECS molecule also interacts with the hydrophobic side chains of Ile93 and Phe96 as well as the hinge molecule. The binding of the hinge molecule is mainly driven by hydrophobic interactions with the side chains of Ala135, Leu138, Tyr139, Phe143 and Phe190. Additionally, the carboxamide moiety of the hinge molecule forms hydrogen bonds to the backbone carbonyl O atoms of Leu138, Tyr139 and Gly141. The interaction pattern of both indole inhibitors in the Sirt2–ADPR–indole complexes is nearly identical. Slight differences can be observed for the conformation of the side chains of Tyr139 and Phe190. Similar interaction patterns for the ECS molecule of both Sirt2–ADPR–indole complexes have also been observed in the crystal structures of Sirt1 and Sirt3 . A conformational change of the hinge loop is only seen in the case of the Sirt2–ADPR–indole complexes.To validate the suitability of the Sirt2–ADPR crystals for the investigation of protein–ligand interactions, we also solved the X-ray structures of Sirt2–ADPR in complex with two indole inhibitors termed CHIC35 and EX243. To our surprise, each Sirt2 molecule contained well defined electron density for two indole molecules. One indole mimics the physiological sirtuin inhibitor nicotinamide and occupies the C-pocket and the adjacent extended C-site. Its binding mode is similar to that observed in the crystal structures of the Sirt1–indole and Sirt3–indole complexes. The other inhibitor molecule binds to the selectivity pocket of the hinge region. Such a second indole molecule is not found in the X-ray structures of the Sirt1–NADb; Rumpf et al., 2015et al., 2015et al., 2015d). Such variable structural changes have not been observed for either Sirt1 or Sirt3 . The hinge molecule may supposedly be of no physiological relevance for Sirt2 inhibition, but it highlights the adaptability of the hinge region of Sirt2 and the selectivity pocket.Occupation of the selectivity pocket has also been observed in other crystal structures of Sirt2 by the dimethylpyrimidine moiety (DMP) of the Sirt2-selective inhibitor SirReal2 (Fig. 6In conclusion, this example of MMS underlines the strength of seeding techniques to obtain crystals for structure–activity studies during drug development. Further experiments are still needed to explore the hinge region of sirtuins, to verify the different characteristics within the sirtuin family and to exclude the possibility that the observations are crystallographic artefacts. However, so far a targeting of the selectivity pocket with hydrophobic moieties and exploiting the flexibility of the hinge loop of Sirt2 seems to be a plausible strategy in the search for new Sirt2-selective inhibitors Fig. 7.5.et al. (2012The following references are cited in the Supporting Information for this article: Clark & Labute 2007 and Szcz al. 2012.human Sirt3, 5d7nPDB reference: human Sirt2, complex with ADPR, 5d7oPDB reference: complex with ADPR and EX-243, 5d7pPDB reference: complex with ADPR and CHIC35, 5d7qPDB reference: 10.1107/S2053230X15019986/cb5089sup1.pdfSupporting information.. DOI:


We demonstrate theoretically and experimentally an interesting opaque state, which is based on an analog of electromagnetically induced transparency (EIT) in mechanism, in a metal hole array of the dimer lattice. By introducing a small difference to the dimer holes of each unit cell, the surface delocalized modes launching out from the dimer holes can have destructive interferences. Consequently, a narrow opaque window in the transparent background can be observed in the transmission spectrum. This surface-mode-induced opacity (SMIO) state is very sensitive to the difference of the dimer holes, which will promise various applications. Electromagnetically induced transparency (EIT) is an interesting phenomenon for both scientific and technological aspects due to its intriguing properties such as reducing the group velocity of the light256791011121314151617181920212223242526282911182829In this work we consider metal hole arrays313220211 = ε2 = 1), a small difference in the dielectric constants of the dimer holes  leads to an EIT-like spectrum  of dimer lattice is schematically shown in the inset of 32341 = 1.21 holes (2 = 1 holes at the higher transmission peak (1 = ε2 = 1) and show it in To confirm the above understanding, we calculate the tangential electric field  on the metal surface at the two transmission peaks and the opaque state. As one expected, at the lower transmission peak great field enhancement is observed around the ε21 holes , while tion peak . At the ion peak . For a cg of the dimer holes .


Low-energy electrons (LEEs) at energies of less than 2 eV effectively decompose 4-nitroimidazole (4NI) by dissociative electron attachment (DEA). The reactions include simple bond cleavages but also complex reactions involving multiple bond cleavages and formation of new molecules. Both simple and complex reactions are associated with pronounced sharp features in the anionic yields, which are interpreted as vibrational Feshbach resonances acting as effective doorways for DEA. The remarkably rich chemistry of 4NI is completely blocked in 1-methyl-4-nitroimidazole (Me4NI), that is, upon methylation of 4NI at the N1 site. These remarkable results have also implications for the development of nitroimidazole based radiosensitizers in tumor radiation therapy. Such a transient negative ion can decompose into a neutral and negatively charged fragment  can induce remarkably selective reactions in molecules,,2 which reaction ):(1a)DEA always competes with the loss of the extra electron recovering the neutral molecule, possibly in an excited state .[In the DNA base thymine for example, the loss of a neutral H atom via DEA at electron energies below 3 eV is bond-selective (only the two N=H bonds are involved), Furtherm as H2O). In theor as H2O).,7 Herein as H2O).The nitroimidazolic compounds are presently under investigation as potential radiosensitizers for so called hypoxic tumors, which are tumors deprived of oxygen. Such lowThe experiments are performed by means of an electron attachment spectrometer consisting of a molecular beam source, an electron monochromator (HEM), and a quadrupole mass filter for analyzing and detecting the ions formed. The 4NI 2 bond; and c) a more complex unimolecular reaction leading to the loss of a neutral .OH unit.In the following we shall demonstrate that the rich chemistry in 4NI induced by slow electrons is completely suppressed in the energy range below 2 eV in its methylated form (Me4NI). This not only concerns the loss of a neutral hydrogen atom via DEA but also bond cleavages and reactions involving the entire molecular system. This significant and surprising effect is demonstrated for a) the loss of a neutral hydrogen atom; b) cleavage of the C=NOFigure .−# the transient intermediate formed upon electron attachment and (M−H)− the closed shell dehydrogenated anion. The reaction enthalpy for DEA reaction (2) amounts to 0.39 eV,[with M 0.39 eV, which ma− exhibits an interesting series of sharp peaks below 2 eV and a broader contribution peaking at 3.4 eV. Sharp peaks at very low energies are often interpreted as VFRs,[The yield of the dehydrogenated ion (M−H) as VFRs, and cons− sharp peaks in the energy below 1.2 eV were observed followed by an unstructured broader distribution peaking at 1.8 eV.A qualitatively similar behavior was recently observed in the DNA base thymine (T), where the loss of H exclusively involves the two N sites, and wherAs the basic DEA mechanism proposed in T most likely also applies for 4NI and Me4NI, it will be briefly considered in the following. It has to be noted that in T the only reaction operative at energies below 3 eV is hydrogen loss, while 4NI shows a much richer chemistry.Methylation of T at the N1 site resulted in a complete quenching of the sharp structures below 1 eV and thus they were associated with DEA, leading to the loss of H exclusively from the N1 site. A detailThe present situation is apparently very similar to that in T, and as already considered above we assign the series of sharp peaks below 2 eV as VFRs involving the N1=H stretch and eventually further vibrational modes. However, we also note that the adiabatic electron affinity of 4NI is 0.73 eV, that is,.−, 127 u) right at threshold − the reaction below 2 eV is completely suppressed in Me4NI. The small peak right at threshold (0 eV) is most likely an artefact and reminiscent to the peculiarities of DEA.[H°) for the DEA reactions (3a) and (3b) is given by the D(C=NO2) bond dissociation energy minus the electron affinity of the fragment on which the excess electron finally becomes localized. For reaction (3a), ΔH° is 0.8 eV obtained from the established average bond dissociation energy in aromatic nitro compounds (D(C=NO2)=3.1 eV[2 (2.27 eV).[3 bond by LEEs but also that of the C4=NO2 bond.Obviously for both of these complementary ions NOs of DEA. The reac2)=3.1 eV) and the2.27 eV). This exa− are not present in the cross-section of the other fragment ions.The last example presented herein concerns an appreciably complex DEA reaction, namely the loss of a neutral OH unit resulting in an ion detected at 96 u from 4NI and at 110 u from Me4NI −), and the formation of CN− and OCN− (not shown here). While CN− can be formed by the excision of two adjacent atoms C and N, the formation of OCN− additionally requires transfer of an O atom. In all of these cases, the corresponding ion yields show sharp structures in the energy range below 2 eV in 4NI which are completely suppressed in Me4NI. These examples further show, that methylation at the N1 site affects the entire molecule and that the VFRs act as effective doorways for a variety of DEA reactions. We also note that it is irrelevant on which C-position the NO2 unit is coupled. In fact, DEA experiments on the isomer 1-methyl-5-nitroimidazole (M5NI) revealed the same fragment ions and virtually identical resonance positions compared to Me4NI.[Along the same lines, for both compounds we observe an ion arising from the loss of a neutral COto Me4NI.3 bond, but suppresses the entire rich chemistry of the molecule in the energy range below 2 eV. With respect to the potential use as radiosensitizers, it can only be stated that in nitroimidazole, secondary LEEs with energies 0–2 eV formed by ionizing radiation generate radicals and among them the .OH radical. The DNA damage by these radicals represents the so-called indirect DNA damage, which is estimated to contribute up to two thirds to the DNA damage induced by ionizing radiation.[In conclusion, it is shown that in nitroimidazole the sharp structures present in the relative partial DEA cross-sections in the energy range below 2 eV are completely suppressed upon methylation on the N1 site. Most remarkably, methylation not only blocks the cleavage of the N1=CHadiation.


The  Monotonicity of curvature is a desirable feature in numerical curve and surface drawing applications e.g. in designing of robotic trajectories Rational cubic trigonometric Bézier curves (RCTBC)The rational cubic trigonometric Bézier curve (RCTBC) Non-rational cubic trigonometric Bézier curveThe parametric non-rational cubic trigonometric Bézier curve is defined asThe above highlighted properties of RCTBC  make it Here It is a special case of  for \doc(iii)Curvature -approximation For the given parametric curves, A GCS mentclass2pt{minimLet the circular arcs have center at origin, the angle between the two radii is entclass1pt{minimaHere entclass1pt{minimaSubstituting the values of }T^π4 in , we get7From  and 8),,8), the The curvature of the Bézier curve , \documed by the  is9\docuHere,Substituting the values of Substituting the values of end curvatures from  in 10),,10), theIt results inNow, either If mentclasspt{minimaSolving the quadratic Eq. , the twoIt can be easily seen that for  root of . The onlmentclasspt{minima root of  is 13) have It can be easily verified that mentclasspt{minimations of  i.e. \doentclass1pt{minimaFrom , 15) is is15) isThe three maximum relative curvature errors of approximation corresponding to three non-rational cubic trigonometric Bézier approximating curves of circular arc are given byThe smallest tolerance is In Cripps et al. , the tolIn the following section, the proposed mentclass2pt{minimThe Here mentclass2pt{minimalues in , 20) an an\documalues in  we have2Here, mentclass2pt{minimof RCTBC , 23) an an\documof RCTBC , the valmentclass2pt{minimThe weights Here, For the control points given in , the parHere,The first and second order derivatives of Here,Substituting the values from  and 29)29) into Here, mentclass2pt{minimThe curvature of the GCS Here In order to determine the optimized values of the free parameters re error  of the dBy simple computation it can be easily observed that the values of first order derivative of RCTBC  at the eTaking the norm on both sides and after some rearrangement, we haveHere mentclass2pt{minimThe arc length of RCTBC  over theM and The above integral cannot be solved analytically. Therefore numerical integration technique is needed to evaluate it. Here, the above definite integral is evaluated by Trapezoidal rule for mentclass2pt{minimSubstituting the values of ,3, from  in 35),,\documenSubstituting the values of ′π4 from  into \documentmentclass2pt{minimhe RCTBC , “G2-appmentclass2pt{minimmentclass2pt{minimrelation  yields tThe optimized values of the free parameters If the control points of the rational cubic trigonometric Bézier curvedefined in  Step 1. CStep 2. Compute the values of free parameters from optimization problems I and II for Step 3. Given Step 4. Put the values of control points obtained from Step 3 into (p 3 into  to obtaiIn this section, entclass1pt{minimaThe circular arc given in Table entclass1pt{minimaentclass1pt{minimaThe Cornu spiral arc given in Table The logarithmic spiral given in Table mentclasspt{minimamentclasspt{minimaThe non-inflecting GCS given in Table The normalized GCS of Table entclass1pt{minimaThe circular arc, Cornu spiral, logarithmic spiral and non-inflecting GCS of Table mentclass2pt{minims et al. .The optimum values of the free parameters of the developed mentclass2pt{minimThe developed mentclass2pt{minimIn this research paper, mentclass2pt{minimmentclass2pt{minimmentclass2pt{minim


These results suggest a potential rolefor meteoritic phosphorus in the origin and development of early life.Phosphorylation of the nucleosides adenosine and uridine by the simple mixing andmild heating of aqueous solutions of the organic compounds with synthetic analogs ofthe meteoritic mineral schreibersite,  Phosphorylation of glycerol by Fe3P to give glycerolphosphate (a component of cell membranes) has been reported previously3P orFe2NiP, and stirred and heated to 80 °C for 2days to 2 weeks  used inthis study was determined to be structurally identical to its meteoritic counterpart byX-ray diffractometry, X-ray photoelectron spectroscopy, and Raman spectroscopy20The resulting solutions were analyzed by UPLC-MS, MS/MS, and 3P, and Fe2NiP. Since 2′-, 3′-, and5′-adenosine monophosphate are isomers, the elution times and massfragmentation patterns 2+ added exceeded the solubility ofboth magnesium phosphate and magnesium phosphite. This result could imply that thephosphorylating agent is possibly a phosphorus species in an oxidation state other than+5 and thus would have sufficient aqueous solubility in the presence of a divalentcation. It was also conjectured that the pH drift from “neutral”to basic was due to the hydrolysis of urea and the formation of ammonium carbonate.Indeed, in the presence of potassium carbonate or ammonium hydroxide  in place of urea, phosphorylation of adenosine was also observed and up to 9.5% (with K2CO3), in agreement with measuredcorrosion rates of 0.1% per week without added solutes23The mechanism of phosphorylation is still unknown and is being actively investigated. Itis possible that the process occurs in solution or on the surface of the schreibersite.As was mentioned previously the yield of organophosphates from these experiments is nothigh, and the concentration of AMP ranges from being undetectable to about600 μM. The yield seems to be controlled by the release of Pfrom phosphide corrosion, which is slow−7 s−1,To determine the relevance of our model environment (schreibersite corroding in anorganic-rich aqueous solution) to prebiotic chemistry, the steady state concentration ofnucleotides is equal to the production rate divided by the hydrolysis rate constant. Inthe absence of biological enzymes hydrolyzing these organophosphates, the rate ofhydrolysis is typically slow(~102 gas3O4) and phosphorus oxyanions is a strongly exergonicprocess releasing 100 kJ·mol−1 at80 °C and it is possible that some portion of this energy isdirected to phosphorylation.Prior work on nucleoside phosphorylation has shown that inorganic phosphate can serve asboth a catalyst and reactant in nucleotide synthesis242 was not excluded from the experiments, prior work24262 in the headspace of theseexperiments or dissolved within the solutions was insufficient to promote oxidation ofthe schreibersite to release the concentrations of P observed.Although OA source of reactive phosphorus may have been an important part of the prebiotic earth,and possibly of Mars3P (0.7 g), and for the other reagents (if used); urea(0.50 g), MgSO4 (0.75 g), 25% soln.NH4OH (0.29 g), K2CO3(1.15 g). For sample U4, 1.5 g of Fe2NiP was usedinstead of 0.7 g Fe3P. The sample of Fe2NiP wassubjected to a series of wet/dry cycles (5×), leading to substantialsurface corrosion. The reagents were added in a glass vial containing7 mL of deionized water, to which the nucleoside was added.


Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.The fibrillar collagen scaffold of the extracellular matrix provides a structural framework for cells in tissues and regulates intercellular communication; its disregulation has been associated with tumour development and progression. Previous work has shown that expression of type I collagen, the most abundant mammalian extracellular matrix protein, is decreased in chemically or virally transformed cells. This negative regulation could be mapped to a proximal COL1A2 promoter element spanning a CME (Collagen Modulating Element) site in SV40‐transformed human fibroblasts (SV‐WI38) that binds an unknown repressing protein. By magnetic bead pull‐down, we observed a multi‐protein complex bound to the CME with preference for single‐stranded over conventional double‐stranded DNA. MALDI‐TOF mass spectrometry of the CME‐binding protein complex revealed involvement of nuclear annexin A2 (AnxA2) which was increased in SV40‐transformed cells. Further EMSA analysis demonstrated that AnxA2 did not directly bind to the DNA but stabilised the complex and led to an increase in protein binding to the CME in SV‐WI38 but not untransformed WI38 cells. Knockdown of AnxA2 by siRNA increased type I collagen production in both WI38 and SV‐WI38 cells; however, these effects were not mediated at the transcriptional level. Rather, our data indicate a novel functional role of AnxA2 in the negative post‐transcriptional regulation of type I collagen synthesis in human fibroblasts. In SV40‐transformed cells, AnxA2 is accumulated at the proximal COL1A2 promoter region, suggesting close association with the transcriptional machinery that possibly facilitates binding to the emerging mRNA, eventually contributing to overall repression of type I collagen protein synthesis. J. Cell. Biochem. 116: 408–417, 2015. © 2014 The Authors.  AnxA2annexin A2CMEcollagen modulating elementCo‐IPcoimmunoprecipitationCOL1A2α2(1) collagen chainEMSAelectrophoretic mobility shift assaySV40 T AgSV40 large T antigenSV‐WI38SV40 transformed WI38 cellsTCEPtris (2‐carboxylethyl) phosphine hydrochlorideType I collagen is the most abundant mammalian extracellular matrix protein and consists of a heterotrimer of two α1(1) and one α2(1) chains. Its expression is regulated by both transcriptional and translational events, as this is a prerequisite for the normal functioning of the connective tissue , this binding was probably not directly through AnxA2 but in complex with other proteins as we observed in this study. We therefore hypothesise that AnxA2 stabilises nuclear protein complexes at the CME region as the anti‐AnxA2 antibody disrupted protein‐DNA binding to some extent while addition of recombinant AnxA2 protein increased complex formation. These effects were more pronounced with SV‐WI38 nuclear proteins compared to WI38 extracts, the latter expressing nuclear AnxA2 to a lower extent, suggesting a role of AnxA2 in the differential regulation of the COL1A2 gene in these two cell lines. Interestingly, we did not detect differences in the sequence of the AnxA2 transcript in the two cell lines (data not shown), suggesting that SV40 transformation did not cause mutations in the AnxA2 gene that could be responsible for the differential type I collagen expression [Lubbe et al., We confirmed the involvement of AnxA2 in CME binding by EMSA studies with a specific antibody against AnxA2 and observed that the antibody did not completely disrupt complex formation to the probe supporting the hypothesis of a large multi‐protein complex interacting with the CME. We further could show that AnxA2 itself did not directly bind to the single‐stranded COL1A2 promoter region (−100/−61)Functional studies confirmed the involvement of AnxA2 in type I collagen expression as altered AnxA2 expression had a substantial influence: siRNA knockdown of AnxA2 was accompanied by significantly elevated type I collagen levels in both WI38 and SV‐WI38 cells. Although this effect was more pronounced in SV‐WI38 cells, type I collagen expression could not be rescued to the level of the untransformed WI38 cells. Conversely, transient overexpression of AnxA2 slightly decreased type I collagen expression in WI38 cells which did not reach the low amounts seen in SV40‐transformed cells (data not shown), suggesting additional repressive mechanisms upon malignant transformation. Surprisingly, alterations of the amount of available AnxA2 did not affect transcription of the COL1A2 gene, suggesting that AnxA2 primarily acts via post‐transcriptional regulation of the gene. Indeed, it has been observed previously that AnxA2 can bind to cis‐acting elements in the 3′‐UTR of specific genes [Vedeler et al., Although we demonstrated a novel role in the negative regulation of type I collagen gene expression, the presence of AnxA2 alone does not explain the observed substantial overall decrease of COL1A2 mRNA and protein upon SV40 transformation. AnxA2 acting at the post‐transcriptional level contributes to type I collagen down‐regulation; however, transcriptional mechanisms do certainly play a significant role in the overall negative regulation. The question of the identity of the proteins that bind to the CME resulting in inhibition of COL1A2 transcription in SV‐WI38 cells still remains. A possible candidate that has been shown to directly interact with AnxA2 is the transcription factor STAT6, leading to enhanced transcriptional activity [Das et al., The role of AnxA2 in the carcinogenesis of human cancers is still debated as it has been shown to be overexpressed in some cancers and downregulated in others, both of which have been identified as beneficial to cancer cells depending on location (Liu et al., AnxA2 is known to be associated with diverse cellular processes including functions in ECM degradation through intercellular and cell‐ECM interactions. Here, we describe a novel function for nuclear AnxA2 as part of a post‐transcriptional regulatory protein complex involved in the regulation of type I collagen. Its regulatory function was more pronounced upon transformation with the SV40 tumour virus which led to nuclear AnxA2 accumulation. We speculate that, under normal conditions, AnxA2 is involved in physiological COL1A2 regulation to prevent excessive deposition of type I collagen which is characteristic of many fibrotic disorders such as systemic sclerosis, hepatic cirrhosis and pulmonary fibrosis [Varga and Jimenez, Supporting Information.Click here for additional data file.


Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible. Electron spins in semiconductor quantum dots (QDs) have relatively long coherence times in solid state devices12369121516173Scale up of the QD system is crucial to realize larger scale quantum gate operations and also explore multi-spin physics. To this end, spin qubit experiments on multiple QDs have been reported in recent years. In triple QDs, PSB has been observed1921222327In this paper, we demonstrate four distinctly addressable electron spin resonances in a QQD. First, we realize few-electron charge states in a QQD required to observe PSB. Second, we observe PSB for readout of ESR signals. The blocked triplet components are created by singlet-triplet mixing induced by the nuclear spins and the MM. Finally, we observe four ESR signals corresponding to the four individual spins in the QQD.L1 and L2 and the stray capacitances Cp1 and Cp2  for the RF reflectometry3132n1, n2, n3, and n4 is monitored by the intensity of the reflected RF signal Vrf1 and Vrf2. A change in the electrostatic environment around the sensing dots changes their conductance, shifts the tank circuit resonance and modifies Vrf1 and Vrf2 measured at fres1 and fres2. A MM is deposited on the shaded region on the top of the device, which creates local magnetic fields to induce ESR. The external magnetic field is applied in the plane along the z axis to induce Zeeman splitting and magnetizes the MM. The shape of the MM is specially designed to realize strong driving of the electron spin rotations by the large field gradient and splitting of the ESR frequencies by the Zeeman field differences between the dotsVrf1 as a function of the plunger gate voltages of QD4VP4 and QD1VP1. We observe the change of Vrf1, as the result of the charge states in the QQD. Charge transition lines with four different slopes are observed reflecting the different electrostatic coupling of the QQD to VP4 and VP1. n1, n2, n3, and n4 are assigned as shown in n1, n2, n3, n4] = . 30VP1 − VP4 plane and we need to switch into VP1 − VP2 and VP3 − VP4 planesTo readout the spin states of the qubits, PSBVP1 and VP4 to observe spin blocked states. The operation schematics are shown in 1 S2001 (in QD4 10S02). The triplet plus component T+1101 in QD1 and QD2 (10T+11 in QD3 and QD4) is populated at the operation point O by using the singlet-triplet mixing S1101 ⇔ T+1101 (10S11 ⇔ 10T+11) induced by the nuclear spins and the MM stray magnetic fieldsVrf1 (Vrf2).We apply voltage pulses on Vrf1 (Vrf2) as a function of VP4 and VP1. The operation pulses are cycled constantly at each point of the graph. We apply voltage pulses with fixed amplitudes as shown as lines in 1 and QD2 (between QD3 and QD4). Note that we are also able to control QD2 and QD3 by VP1 and VP4 because of the finite capacitive coupling. Sensor 1 is used for Vrf1 (Vrf2) are observed around M when the operation point O hits the singlet-triplet mixing point. These correspond to the spin blocked signals.fESR). The operation schematics are shown in Bz between QD1 and QD2 (QD3 and QD4) by the MM will be larger than the singlet-triplet splitting at the operation point O and the eigenstates are ↓↑1101 and ↑↓1101 (10↓↑11 and 10↑↓11), not S1101 and T0 1101 (10S11 and 10T0 11) (see 1101 in QD1 and QD2 (10↓↑11 in QD3 and QD4) by adiabatically pulsing from S2001 (10S02). Then, we apply microwaves at the operation point O. These applied microwaves create an oscillating electric field around the gate R and thus induce movements of the QD electron’s wave functions. These oscillations of the wave functions are converted into oscillating magnetic fields along the x axis perpendicular to the external magnetic field in the field gradient created by the MM and ESR is induced12+1101 or T−1101 (10T+11 or 10T−11) are populated by ESR and detected as the   charge states.Next, we apply a microwave voltage on gate R to induce ESR (with the frequency  11) see . We prepPS as a function of fESR and the external magnetic field Bext. PS is calculated from Vrf1 (Vrf2) by using the method reported in the refs μs and set shorter than the relaxation time T1 > 100 μs. We can see the decrease of PS when the applied microwave frequency matches the external magnetic field plus the z component of the stray field created by the MM hfESR = gμ(Bext + BMMz). The ESR dips of PS are also observed in PS as a function of Bext at fESR = 3265 MHz.g| = 0.37 ± 0.03 that is consistent with reported values in previous experiments3839The slopes of the ESR lines in Bext and fESR such that the separation of the ESR dips is larger than their width as in BMMz12, BMMz13, BMMz14 are evaluated as BMMz12 = 28 mT, BMMz13 = 9 mT, BMMz14 = 73 mT. If there is no misalignment of the QD positions, BMMz12 < BMMz13 < BMMz14 is expected from the design of the MMz direction, which is possible in this QQD device .


On the formation of Na2O2·2H2O, the charge overpotential of sodium–oxygen cells significantly increases. This verification addresses the origin of conflicting discharge products and overpotentials observed in sodium–oxygen systems. Our proposed model provides guidelines to help direct the reactions in sodium–oxygen batteries to achieve high efficiency and rechargeability.With the demand for high-energy-storage devices, the rechargeable metal–oxygen battery has attracted attention recently. Sodium–oxygen batteries have been regarded as the most promising candidates because of their lower-charge overpotential compared with that of lithium–oxygen system. However, conflicting observations with different discharge products have inhibited the understanding of precise reactions in the battery. Here we demonstrate that the competition between the electrochemical and chemical reactions in sodium–oxygen batteries leads to the dissolution and ionization of sodium superoxide, liberating superoxide anion and triggering the formation of sodium peroxide dihydrate (Na Sodium-oxygen batteries are promising energy storage devices but the nature of their discharge products remains unresolved. Here, the authors reveal that the dissolution and ionization of sodium superoxide leads to the formation of other phases, which increases the charge overpotential of the cell. However, this system suffers from poor cycle stability and efficiency, which has retarded the feasibility of its use in practical systems82 batteries with a few important merits+, Na resources are readily available, are less expensive than Li and can easily replace Li in the battery chemistry. It has been reported that the redox reactions in the sodium–oxygen (Na–O2) battery result in an extremely low charge overpotential (∼0.2 V) despite involving the formation of micrometre-sized sodium superoxide (NaO2) cubic crystallites111213To address the increasing use of renewable energy and launch of electric vehicles, the need for rechargeable batteries with high-energy densities has been growing more rapidly than ever before134562 cells appear to be more diverse than those of Li–O2 cells. Contrary to the initial report of NaO2 discharge products, some recent lines of work could not reproduce either the formation of the discharge product NaO2 or the low charge overpotential15162O2)15162O2·2H2O)182 system. Many groups have attempted to determine the reasons for these discrepancies; however, to date, the main cause of the divergence of reactions has not been identified. Janek et al. investigated the effect of different carbon electrodes; Guo et al. and Shao-Horn et al. addressed this issue but observed no critical differences among the cases1220Notably, however, the reactions of Na–O2 batteries involving a series of electrochemical and chemical reactions as a function of time. Under systematic control of the operating conditions, we observe that the galvanostatic charge/discharge profiles are sensitively affected by the conditions and durations of the electrochemical operations. It is also revealed that the electrochemically formed NaO2 is unstable and degrades into Na2O2·2H2O in the absence of an applied current. The spontaneous dissolution and ionization of NaO2 liberates the free O2− in the electrolyte and promotes side reactions involving the formation of Na2O2·2H2O. On the basis of these observations, we propose reaction mechanisms of Na–O2 batteries under various operating conditions. This report is the first to reveal the relationships among the different discharge products observed in Na–O2 batteries, which broadens our understanding of the electrochemical and chemical reactions in Na–O2 batteries. Furthermore, these discussions may offer insight and guidance to the metal–air battery community in terms of regulating the kinetics of the intertwined reactions.In this work, we demonstrate the interplay of the diverse reactions in Na–O2 cells, we carefully assessed the effects of operating parameters on the resulting electrochemical profiles. Among the various parameters examined  of the carbon electrode. The Raman signals at 1,156 and 1,136 cm−1 are attributed to the O–O stretch bonding in NaO2 and Na2O2·2H2O, respectively2 and Na2O2·2H2O with time is clearly illustrated in 2 to proton-containing Na2O2·2H2O indicates a source of protons in the electrochemical cell. Considering the low water content in the electrolyte used for the cell (less than ∼5 p.p.m.), which is insufficient to form the phase  spectroscopy, which is useful for detecting the magnetic responses of the unpaired electrons in radicals such as O2− /k′≈1.24 h , the dissolution is not favourable even in NaO2. Molecular dissolution energies of NaO2 in model solvents are ∼0.6 eV, which roughly corresponds to one molecule dissolution among 1010 formula units of NaO2. On the other hand, it markedly diminishes to 0.17 eV (one molecule among 103 formula units of NaO2) in ɛ=30 , and the charge process is the reverse reaction (Reaction 2). After or during the discharge, the NaO2 is prone to dissolution and ionization into the electrolyte based on the solvating energy (ΔGsol) in the solvent (Reaction 3)2 generates O2−, which can degrade the surrounding molecules because of its chemical instability. Typically, the liberated O2− is a strong reagent for the abstraction of H+ from the electrolyte solvents (Reaction 4)+ abstraction41Ka) of the solvent. Some hydroperoxyl radicals (HO2) might be formed during this process, resulting in the nucleophilic attack of the H+-lost solvent (Reaction 5)2 can be helpful in promoting the solution-mediated discharge/charge process as recently reported by Xia et al.2 is dominant, the liberation of O2− is overwhelmingly larger than a possible HO2 formation, inducing the H+ abstraction from the neighbouring electrolyte solvent. Meanwhile, the solvent undergoes oxidative decompositions to produce byproducts such as carbon dioxide (CO2), water (H2O) and hydroxyl anions 2 leads to disproportionation into hydrogen peroxide (H2O2) and O2 (Reaction 7)+ and OH−, which is effectively the dissolution state of sodium hydroxide (NaOH), a solid crystallite of NaOH can precipitate with a higher concentration of OH− produced. Further reaction between NaOH and H2O2 from Reaction 7 leads to the formation of Na2O2·2H2O via peroxo-hydroxylation, whose reverse reaction is well known (Reaction 8)2− plays an important role after the dissolution of NaO2 in converting the discharge product to Na2O2·2H2O via degradation of the electrolyte involving OH− and H2O2. These identifications strongly support the proposed mechanism of competing electrochemical and following chemical reactions in Na–O2 batteries. The detailed discussions are provided in On the basis of the previous reports and our new findings, we propose a mechanism that describes the electrochemical and chemical reactions in Na–O2 batteries. The solvating environment was demonstrated to alter the stability of the intermediates, such as a lithium superoxide (LiO2), thus affecting the overall reaction paths232 is a precedent phase with the direct reaction of a Li cation and superoxide anion (O2−), which readily decomposes into lithium peroxide (Li2O2) via either an electrochemical surface reaction or disproportionation232 is known to be unstable462 might be dissolved into the electrolyte and aid in the formation of the toroidal Li2O2 via a solution reaction under highly solvating conditions2 shares this dissolving nature with LiO2 even though the thermodynamic stability of NaO2 warrants its formation as a discharge product. The significant dissolution of NaO2 supports the conclusion that the dominant reaction in Na–O2 batteries relies on the solution-mediated reactions of nucleation and growth of NaO2 (refs 2 under various conditions (such as different electrolytes and current rates). This is also supplemented with the recently reported observations21It is noteworthy that a similar behaviour has been recently reported for reactions in Li–OaO2 refs , 24, 31 2 batteries. The time-dependent chemical reactions were identified as being triggered from the dissolution and ionization of the electrochemically formed NaO2 in the electrolyte. The liberated O2− reacts with the electrolyte solvent to form Na2O2·2H2O following a series of intermediate steps. The Na2O2·2H2O in the air electrode requires a higher energy for the decomposition, which leads to the increased charge overpotential and irreversibility of Na–O2 cells. This report is the first to correlate the electrochemical and chemical reactions with the operating conditions in Na–O2 batteries, and our findings concerning the relationships among different phases resolve the conflicting observations of different discharge products in previous Na–O2 batteries. To prepare a better performing Na–O2 battery, a strategy to prevent the transformation of NaO2 into Na2O2·2H2O while still allowing the solution-mediate discharge reaction is necessary. We hope that the findings of this study can provide a basis for researchers to navigate and direct the reactions in Na–O2 batteries to achieve high efficiency and rechargeability.We successfully demonstrated the interplay of the diverse competing reactions in Na–O2O impurities.The carbon cathode was prepared by casting Ketjen Black carbon paste and polytetrafluoroethylene  with a mass ratio of 9:1 in a solution of isopropanol  and N-methyl-2-pyrrolidone  with a volume ratio of 1:1 on Ni mesh current collectors. The carbon-coated Ni mesh was dried at 120 °C and heated at 400 °C for 4 h in Ar to completely remove any residual H2 level<0.5 p.p.m. and H2O level<0.5 p.p.m.). The Na–O2 cells were assembled as a Swagelok-type cell with stacking of the Na metal anode, electrolyte-soaked separators and carbon cathode, which was punched with a half-inch diameter. The Na metal anode was carefully prepared by milling dry Na metal chunks  after removing the contaminated surfaces. The electrolyte was prepared with diethylene glycol dimethyl ether , which contains 0.5 M NaCF3SO3 . The solvent was dried using 3-Å molecular sieves for over 1 week, and the salt was also kept in a vacuum oven at 180 °C for the same time before use. The final water content in the electrolyte was less than 10 p.p.m. according to a Karl–Fisher titration measurement. The amount of electrolyte used for the cell was 200 μl. Two sheets of Celgard 2400 were used as separators. Electrochemical battery tests of the Na–O2 cells were conducted using a potentio-galvanostat . All the cells were relaxed under 770 torr of O2 pressure for 10 min before the tests. After being saturated with O2 gas, the cells were operated in the closed state with a limited capacity of 1 mAh, lower voltage cutoff of 1.6 V and upper voltage cutoff of 4.2 V. Special protocol based on a pulsed current was applied during the charge to avoid dendritic failure of the Na metal anode. The on/off time ratio of the pulse charge was 1:4 (applying current for 0.5 s and relaxing for 2 s). More details about our charge protocol are provided in All the procedures described below were performed in an Ar-filled glove box  in a glove box to remove any residual electrolyte. X-ray diffraction spectra of the cathodes were obtained using a Bruker D2-Phaser (Cu Kα λ=1.5406 Å) with the aid of a specially designed air-tight holder to prevent outer atmospheric contamination. Raman spectra were obtained using a Horiba Jobin-Yvon LabRam Aramis spectrometer (the 514-nm line of an Ar–ion laser was used as the excitation source). The scattered light of the Raman signal was collected in a backscattering geometry using the × 50 microscope objective lens. Field-emission scanning electron microscopy  was used for the morphological observations after Pt coating. For ESR characterization, the collected powder from the discharged cathodes after rinsing to remove the residual used electrolytes was soaked in fresh electrolyte. After immersing the powdery discharged cathodes, the ESR signal of the electrolytes was measured at room temperature using a JEOL JES-TE200 ESR spectrometer every 10 min for 12 h using a liquid quartz cell. The microwave X-band frequency was 9.42 GHz at 1-mW power.The discharged cathodes after the different rest times were collected from disassembled Na–OxO2, M: Li, Na, x=1 or 2). The following equations were used considering both the (1) molecular and (2) ionized solvated states:First-principles calculations were performed using the spin-polarized generalized gradient approximation. A continuum solvation model VASPsol49 code wEsolvated(MxO2) and Ebulk(MxO2) are the total energies of the solvated and bulk MxO2 per formula unit, respectively. The solvated species (ions or molecules) were placed in a 13 Å × 13 Å × 13 Å cell as an isolated species. We used the plane-wave basis with an energy cutoff of 550 eV and a Monkhorst-Pack 2 × 2 × 2 k-point mesh. On the basis of previous reports50H), we neglected the entropy effect of the solvation in these calculations.where How to cite this article: Kim, J. et al. Dissolution and ionization of sodium superoxide in sodium–oxygen batteries. Nat. Commun. 7:10670 doi: 10.1038/ncomms10670 (2016).Supplementary Figures 1-11, Supplementary Notes 1-10 and Supplementary References


LRRK2)‐encoding gene are the most common cause of monogenic Parkinson's disease. The identification of LRRK2 polymorphisms associated with increased risk for sporadic Parkinson's disease, as well as the observation that LRRK2‐Parkinson's disease has a pathological phenotype that is almost indistinguishable from the sporadic form of disease, suggested LRRK2 as the culprit to provide understanding for both familial and sporadic Parkinson's disease cases. LRRK2 is a large protein with both GTPase and kinase functions. Mutations segregating with Parkinson's disease reside within the enzymatic core of LRRK2, suggesting that modification of its activity impacts greatly on disease onset and progression. Although progress has been made since its discovery in 2004, there is still much to be understood regarding LRRK2′s physiological and neurotoxic properties. Unsurprisingly, given the presence of multiple enzymatic domains, LRRK2 has been associated with a diverse set of cellular functions and signalling pathways including mitochondrial function, vesicle trafficking together with endocytosis, retromer complex modulation and autophagy. This review discusses the state of current knowledge on the role of LRRK2 in health and disease with discussion of potential substrates of phosphorylation and functional partners with particular emphasis on signalling mechanisms. In addition, the use of immune cells in LRRK2 research and the role of oxidative stress as a regulator of LRRK2 activity and cellular function are also discussed.Mutations in the leucine‐rich repeat kinase 2 ( The GTPase domain, comprising of Ras of complex protein (ROC) terminating with a spacer domain called the C‐terminal of the Roc‐domain (COR), is immediately followed by the kinase domain, belonging to the serine/threonine kinases. This enzymatic core is surrounded by protein–protein interaction domains comprising the armadillo, ankyrin and leucine‐rich repeat (LRR) domains at the LRRK2 N terminus G2019S mutation is the most frequent pathogenic mutation G2019S mutation is rare in Asia, although it is relatively frequent in Southern Europe, reaching a maximum frequency in Ashkenazi Jewish (10–30% of PD patients are G2019S carriers) G2019S carriers) G2019S‐LRRK2 mutation appears to have a clear age‐dependent effect and varies from around 50% at age 50, to ~ 74% at age 79 G2019S mutation occurs in the kinase domain of LRRK2, leading to an increase in kinase activity G2019S‐LRRK2 in cell lines and primary neuronal cultures I2020T) was isolated in the Japanese family in which the PARK8 locus was first described as being associated with PD G2019S‐LRRK2 under the same experimental conditions I2020T‐LRRK2 has been shown to induce toxicity in overexpressing models G2019S or I2020T mutation suggests that an increase in LRRK2 kinase activity is sufficient per se, but not essential to trigger neurotoxicity.In the overall LRRK2‐PD population, the G2019S mutation is situated within this segment of the activation loop and it has been speculated that the glycine residue here imparts conformational flexibility The kinase function of LRRK2 is of particular interest, especially to pharmacologists, because kinases are typical targets of pharmaceuticals. The LRRK2 kinase domain is thought to assume a typical kinase fold, in which an N‐terminal and a C‐terminal sub‐domain can be identified, with the active site sitting in the cleft between the two. The activation loop, thought to be situated in the C terminus of the kinase domain R1441C, R1441G and R1441H mutations are located in the GTPase domain of LRRK2; the R1441G mutation is especially frequent in the Basque population where it accounts for > 40% of familial PD cases Y1699C mutation lies within the spacer domain, between the GTPase and kinase domains, and is responsible for one of the largest PD pedigrees in the UK with 25 affected subjects over four generations R1441C/G/H mutations showed decreased GTP hydrolysis Y1699C mutation G2019S‐LRRK2. R1441C, R1441G and Y1699C LRRK2 have been associated with cellular toxicity The in vitro assays as opposed to cellular systems. Moreover, if GTPase activity were regulated solely by autophosphorylation, it would be logical to assume that mutations within the kinase domain would subsequently alter GTP binding/hydrolysis. The hydrolysis of GTP to GDP has been shown to be altered in cell cultures expressing mutations in the GTPase domain G2019S, which occur in the kinase domain of the protein, do not disrupt this in vitroet al. in vitro in a synergistic manner. Clearly, the enzyme activities of LRRK2 undergo intramolecular regulations that can also be influenced by other LRRK2 interactors.The presence of a double enzymatic core within the LRRK2 protein suggests that these two functions might influence each other's activities. Autophosphorylation of specific residues Fig.  within tLRRK2 gene which are very rare, and some of these are also present in controls  were among the first to be investigated as potentially related to LRRK2. MAPK pathways are composed of three layers of proteins able to activate each other in a cascade. At the top layer is a kinase identified as MAP3K that is able to phosphorylate and activate a MAP2K in the second layer, which consequently activates the final MAPK, thus inducing a change in transcription. LRRK2 was able to bind to and phosphorylate MAP2K, ‐3, ‐4, ‐6 and potentially ‐7 G2019S‐LRRK2, leading to hyperphosphorylation of their effectors; ERK1 and ERK2. The alteration of this MAPK pathway was considered responsible for the G2019S‐LRRK2 mediated increase in basal autophagy Another MAPK pathway was recently associated with LRRK2 after MAP2K1 and MAP2K2  were found to be activated by The Wingless signalling pathway (Wnt) is responsible for the activation of the transcription factor β‐catenin, and is able to regulate nearly 400 genes It is interesting to note that LRRK2 is also involved in cancer signalling pathways. Thus, LRRK2 has been associated with MET signalling pathways in papillary renal and thyroid carcinomas; in particular, LRRK2 knockdown was shown to reduce tumour proliferation with concomitant increase in cell death, and reduction of MET signalling through the effectors target of rapamycin (TOR) and signal transducer and activator of transcription 3 (STAT3) G2019S‐LRRK2 may be able to bind to and phosphorylate Bcl‐2, with a consequent reduction of the mitochondrial membrane potential, thus stimulating mitophagy LRRK2 has been suggested to modulate nicotinic adenine acid dinucleotide phosphate receptors, with consequent activation of a calcium signalling cascade (mediated by CaMKKβ) that would eventually activate adenosine monophosphate‐activated protein kinase (AMPK) to coordinate different cellular functions related to nutrient homeostasis and energetic balance Drosophila orthologue were shown to be able to phosphorylate eukaryotic initiation transcription factor 4E binding protein (4E‐BP) G2019S‐LRRK2 PD brains, or in LRRK2 knockdown or G2019S overexpressing mice in vitro assays and low‐complex model organisms may not be directly transferable to mammalian systems. However, there are other plausible hypotheses to justify this discrepancy; there may be specific signals needed to activate the function of LRRK2 over 4E‐BP in mammalian systems, or the involvement of LRRK2 within this branch of the TOR pathway may be cell specific, meaning that a cautious selection of cell type is needed to be able to detect it.Human LRRK2 and its G2019S‐LRRK2, as well as LRRK2 knockout mice, exhibited increased expression of mTOR in the kidneys, whereas knockin transgenic mice expressing a kinase inactive form of LRRK2 showed the opposite Knockin transgenic mice expressing Drosophila proposed that LRRK2 associates with Drosophila Argonaute‐1 (dAgo1) and human Argonaute‐2 (hAgo2), thus modulating the RNA‐induced silencing complex Drosophila model and human neurons Another study in A recent study in LRRK2 knockout mice showed that LRRK2 interacts with the PKARIIβ subunit of the protein kinase A holoenzyme regulating its localization. Aberrant localization of protein kinase A in knockout mice increased cofilin and glutamate receptor 1 (GluR1) phosphorylation, thus interfering with synaptogenesis and dopamine signalling through the dopamine receptor Drd1 A final remark should be for the 14‐3‐3 proteins that have been demonstrated to be LRRK2 interaction partners involved in the regulation of LRRK2 cellular localization in vitro kinase assays that have been difficult to replicate under expression of physiological levels of LRRK2. However, the intriguing idea behind this plethora of possible LRRK2‐modulated signalling pathways is that LRRK2 might play more than one role depending on the cell type in which it is expressed. Moreover, the presence of mutations in the LRRK2 sequence may cause a gain of novel functions, thus implicating LRRK2 in pathology pathways that may not be relevant under physiological conditions. This may support the existence of different functions for LRRK2 in PD, cancer and immune disorders, and it suggests caution in extrapolating general information from different model systems and from experiments involving the use of mutant LRRK2.An interesting variety of signalling pathways have been associated with LRRK2 thus far from various reports  G2019S‐LRRK2 has confirmed a reduction in macroautophagy in comparison with healthy controls DrosophilaAutophagy was initially associated with LRRK2 when blocking macroautophagy through the knockdown of essential autophagy proteins (Atg7 and Atg8) was sufficient to attenuate the toxicity of overexpressed G2019S‐LRRK2 overexpression presented fragmentation of the Golgi complex Recent accruing evidence suggests a role for LRRK2 in vesicle dynamics and retromer function. LRRK2 was found to be associated with membranous structures and vesicles in the mammalian brain Drosophila, LRRK2 was shown to phosphorylate EndoA, decreasing EndoA affinity for membranes and affecting EndoA‐dependent membrane tubulation. The G2019S mutation impeded synaptic endocytosis LRRK2 has been described as regulating synaptic endocytosis via association with Rab5b; siRNA knockdown of LRRK2 markedly reduced synaptic vesicle endocytosis G2019S‐LRRK2 LRRK2 has been proposed to participate in the control of synaptic vesicle exocytosis by phosphorylating Snapin, and thus regulating soluble NSF attachment protein receptor (SNARE) complex functionality and late endosomal transport Recently, LRRK2 has been described as colocalizing with Sec16A, a protein involved in the formation of the endoplasmic reticulum exit site. Loss of LRRK2 led to a reduction in protein transport to the dendritic spine with a consequent reduction in glutamate receptors onto the synapse surface et al. et al. G2019S‐LRRK2 in primary neurons induced lysosomal swelling and accumulation of a component of the retromer complex; the mannose phosphate receptor G2019S, R1441C and Y1699C enhanced Golgi clearance, but the hypothesis‐testing mutations that decrease GTP binding, the T1348N, or the kinase‐inactive K1906M, did not sustain Golgi clearance, suggesting that both kinase and GTPase activities are required for maintaining this cellular process DrosophilaTwo interesting studies by MacLeod Many LRRK2 transgenic models have been created in an attempt to model PD. Although none have alterations resembling PD and the vast majority show no signs of neurodegeneration either, some exhibit a variety of synaptic alterations G2019S mutation showed abnormal mitochondrial morphology R1441C and G2019S mutations G2019S transgenic mice, ultrastructure examination showed an accumulation of damaged mitochondria, consistent with altered mitophagy in aged mice G2019S‐LRRK2 and A53T α‐synuclein, structural and functional abnormalities within the brain mitochondria suggested LRRK2 to induce a mitochondrial phenotype G2019S‐LRRK2 in SH‐SY5Y cells caused mitochondrial uncoupling, leading to reduced membrane potential and increased oxygen consumption G2019S or R1441C‐LRRK2 demonstrated increased mitophagy associated with altered calcium levels G2019S or R1441C‐LRRK2 showed normal mitochondrial electron transport chain, they showed increased vulnerability to chemical stressors and disrupted mitochondrial movement G2019S expressing HEK cells and G2019S‐LRRK2 fibroblasts LRRK2′s putative association with mitochondria suggests that it might play a role in mitochondrial dysfunction driving PD pathogenesis. Indeed, fibroblasts from PD patients carrying the WT‐LRRK2 may be neuroprotective, attenuating H2O2‐induced cell‐death in HEK293 and SH‐SY5Y cells G2019S mutation were found to be more sensitive to H2O2 exposure with increased caspase 3 activation and cell death The same causative hierarchy is yet to be determined for the association of LRRK2 with reactive oxygen species (ROS). Elevated ROS has been implicated as a pathological feature of PD; Caenorhabditis elegansSeveral mechanisms have been proposed to control the link between increased vulnerability to ROS and LRRK2 neurotoxicity. For example, increased kinase‐dependent interactions were shown between LRRK2 and two of its hypothetical substrates, DLP1 Despite LRRK2 having ubiquitous expression, substantial levels of LRRK2 protein and mRNA are present in peripheral blood mononuclear cells, lymph nodes, spleen The manifestation of these very specific functions of LRRK2 within the immune system opens up the intriguing hypothesis that LRRK2 may play different roles within different cell types and tissues. This scenario could be explained only by the presence of molecular mechanisms allowing the same LRRK2 protein to behave differently in different tissues; those mechanisms may be based on cell‐type‐specific LRRK2 differential splicing, or on tissue‐specific expression of LRRK2 activators, substrates and partners. Little is known about LRRK2 splicing and it may be reasonable to suppose that different cell types express different LRRK2 isoforms potentially involved in different cellular functions. The first study performed in mice showed indeed a differential expression of two splicing variants of LRRK2 in primary neurons, astrocytes and microglia Different cell lineages may express different LRRK2 partners able to specifically regulate LRRK2 levels and phosphorylation; features that are supposed to be linked with LRRK2 activation/repression. This assumption was demonstrated by the observation that LRRK2 expression and activity can be modulated via immune‐cell‐specific signalling pathways Fig. . For exaThe fact that LRRK2‐PD has an almost indistinguishable pathological phenotype from sporadic PD and the presence of a druggable kinase activity within LRRK2 were sufficient reasons for researchers to look at this protein as a potential target for a neuroprotective treatment in PD. Most notably, the development of selective pharmacological inhibitors of LRRK2 kinase activity is an active area of research with at least six potential LRRK2 inhibitors described in the literature and many leading pharmaceutical companies working on LRRK2 research programmes  showed selective inhibition of WT and in vivo in rat models expressing human LRRK2 (see Ref. Based on the structure of the HG‐10‐102‐01(4) compound, two further compounds were developed recently; the GNE‐0877 and GNE‐9605 T2397M‐mutant LRRK2 patients have reportedly lower levels of LRRK2 protein activity within their immune cells Clearly, the developments in identifying LRRK2 kinase inhibitors and a potential to treat PD have now entered an exciting phase but should be viewed with cautious optimism. A recent report demonstrated abnormal lung, kidney and liver pathology in LRRK2 knockout rats compared with rats expressing physiological levels of LRRK2 It is evident that there is still much to be understood about the LRRK2 protein regarding both its physiological and neurotoxic properties. A large variety of functions have been associated with LRRK2, both in terms of its physiological and cellular roles, and its pathological role during neurodegeneration Fig. . These cet al. It is still unknown whether LRRK2 may interpret different roles in different cell types, thus giving origin to cell‐specific phenotypes; in light of this, LRRK2 functions may be tissue specific, thus giving an explanation for the plethora of activities described up to now in diverse model systems Fig. . AnalysiG2019S pathology It will be crucial for future research on LRRK2 to consider the early events in neurodegeneration, as LRRK2 genetic penetrance varies between 30% and 80% depending on age. Although the loss of dopaminergic neurons is a key pathological characteristic of PD, it is preceded by many other dysregulations, which occur prior to the development of motor symptoms. It is the mechanism of LRRK2 associated with these events that needs to be uncovered. For example, LRRK2 has been associated with Wnt signalling pathways Finally, it is important that all progress in LRRK2 research is interpreted carefully. The development of LRRK2 kinase inhibitors gives us cause for optimism for potential treatment for PD, but clearly the effects of inhibiting kinase activity should be gauged in the context of the entire LRRK2 protein.Rebecca Wallings and Claudia Manzoni have contributed equally to the review. Rina Bandopadhyay has thoroughly revised and proof read the manuscript. All three authors have contributed to parts of the manuscript.


With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Here, building on the recent remarkable progress in optical control of motional states of diamonds, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum process tomography, we demonstrate average teleportation fidelity (90.6±1.0)%, clearly exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for optomechanical quantum control and quantum information science. Quantum teleportation has found important applications in quantum technologies, but pushing it to macroscopic objects is challenging because of the fragility of quantum states. Here, the authors demonstrate teleportation of states from light beams to the vibrational states of a macroscopic diamond sample. Quantum teleportation has found important applications for realization of various quantum technologies12356791011151719202122232425262728292526192019282920212223203 in size under ambient conditions. The vibration states are carried by two optical phonon modes, representing collective oscillation of over 1016 carbon atoms. To facilitate convenient qubit operations, we use the dual-rail representation of qubits instead of the single-rail encoding used in the previous experiments202122In this paper, we report an experimental demonstration of quantum teleportation from light beams to the vibrational states of a macroscopic diamond sample of 3 × 3 × 0.3 mmWe illustrate our entanglement generation and quantum teleportation scheme in 20ps, an excitation in the optical phonon mode and a Stokes photon of wavelength 780 nm in the forward direction %, significantly higher than the criterion of Fe=0.5 for verification of entanglement20Fe=(89.7±1.2)% after subtraction of the accidental coincidence.Our experimental set-up is shown in To perform quantum teleportation using the photon–phonon entanglement, we first transform the effective photon–phonon-entangled state to the standard form of in〉 is the input state at Alice's side and ρout denotes the output density matrix at Bob's side, reconstructed through quantum state tomography measurements. In Fp=(85.9±1.6)%, which corresponds to a teleportation fidelity The experimental result for teleportation is shown in Teleportation of the quantum states from a photon to the vibration modes of a millimeter-sized diamond under ambient conditions generates a quantum link between the microscopic particle and the macroscopic world around us, usually under the law of classical physics. In our experiment, the ultrafast laser technology provides the key tool for the fast processing and detection of quantum states within its short life time in macroscopic objects, consisting of many strongly interacting atoms that are coupled to the environment. Combined with the tunability of the wavelength for the retrieval laser pulse251920ɛ : ρf≡ɛ(ρi) that transfers an arbitrary input state ρi to the output ρf. It can be characterized by a unique process matrix χmn through the map Em. In our experiment, we set the basis operators Em to be the identity operator I and the three Pauli matrices X=σx, Y=−iσy, Z=σz. This corresponds to a choice of six complementary input states χ through the maximally likelihood estimationFp=Tr(χχid), where χid is the identity process matrix corresponding to the perfect case. The process fidelity Fp determines the average teleportation fidelity QPTla  ref. , where  The data that support the findings of this study are available from the corresponding author upon request.How to cite this article: Hou, P.-Y. et al. Quantum teleportation from light beams to vibrational states of a macroscopic diamond. Nat. Commun. 7:11736 doi: 10.1038/ncomms11736 (2016).


We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters  at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. Active matter is a rapidly growing branch of nonequilibrium soft matter physics with relevance to chemistry, biology, and complex systems1345678910111213141516171819202122232425262728293031323334353637383940414243443567891011121314151618192021222324262728293435363738394041424344More recently, ratchet effects have been observed in the absence of an external drive for systems of self-propelled particles6791011121314151610In nature and technology, many systems are mixtures of different particle types. Studying and comparing the passive and active motions can provide insight into out-of-equilibrium phenomena46Ly) in the y-direction and periodic boundary conditions (the period Lx) in the x-direction  is immersed in a ‘sea’ of clockwise (or counterclockwise) particles . The dynamics of particle i are described by the position θi of the polar axis i-th particle has radius ai (ai = a0 for active particles and ai = ap for the passive particle). The particle i obeys the following overdamped Langevin equations2438We consider the mixtures of the passive and active particles moving in a two-dimensional channel with hard walls (the height shown in . A M-shaμ the mobility and ξi(t) are Gaussian white noises with zero mean and correlations α, β labels denote Cartesian coordinates) and δ the Dirac delta function. D0 and Dθ denote the translational and rotational diffusion coefficients, respectively. Ω is the angular velocity and its sign determines the chirality of active particles. We define particles as the clockwise particles for negative Ω and the counterclockwise particles for positive Ω.with Fij between particles i and j is assumed to be of the linear spring form with the stiffness constant k: Fij = 0 otherwise. The interactions between particles are radially symmetric and do not directly coupled to angular dynamics. We define the ratio between the area occupied by particles and the total available area as the packing fraction N is the total number of particles. For the high packing fraction ϕ in excess of 1, particles of either species overlap on average.The force and the other parameters can be rewritten as x-direction average velocity because particles are confined in the y-direction. The average velocity along the x-direction in the asymptotic long-time regime can be obtained from the formula The behaviors of quantities of interest can be corroborated by Brownian dynamic simulations performed by the integration of Langevin 7 and the transient effects were estimated and subtracted. The integration step time Δt was chosen to be smaller than 10−4. With these parameters, the simulation results are robust. Unless otherwise noted, our simulations are under the parameter sets: D0 = 10−4, Dθ = 5 × 10−4, Lx = 40.0, Ly = 20.0, and ap = 3.0.For numerical simulations, the total integration time was more than 10v0cos θ in As we know, in nonlinear systems, the ratchet setup demands two key ingredientsVs as a function of the angular velocity Ω for different values of ϕ. For active particles (denoted by the red lines), Vs is negative for Ω > 0, zero at Ω = 0, and positive for Ω < 0. The movement direction of active particles is completely determined by the sign of Ω. In other words, active particles with different chiralities move to different directions and can be separated. In addition, when Vs tends to zero. Therefore, there exists an optimal value of Now we explain the rectified mechanism of chiral active particles in the upper-lower asymmetric channel see . In a wiVs = 0) due to the absence of the fluctuating input zero-mean force. However, when the passive particle was immersed in the ‘sea’ of active particles, the interactions from active particles can break the thermodynamical equilibrium and make the passive particle move directionally. At the high packing fraction  are different from those of active particles (red lines). Interestingly, for very small values of For the single passive particle, the ratchet effect disappears  reducing the self-propelled driving, which blocks the ratchet transport and (B)activating motion in an analogy with the thermal noise activated motion for a single stochastically driven ratchet, which facilitates the ratchet transport. When the packing fraction increases from zero, the factor B first dominates the transport, so the average velocity increases with the packing fraction. However, when the packing faction become large, the factor A dominates the transport, thus the average velocity decreases with increasing ϕ. Therefore, there exists an optimal value of ϕ at which the average velocity is maximal.Vs vs ϕ) becomes more complicated. When Vs is positive and there exist two peaks in the curve. For very small values of Vs is negative for ϕ < ϕc, zero at ϕ = ϕc, and positive for ϕ > ϕc. Therefore, we can also have current reversals by changing the packing fraction.For the passive particle  at which the average velocity takes its maximal value. Our results should be of considerable practical and theoretical interest, because they provide new insights into active matter and non-equilibrium systems. Applications of these results can be envisioned for ion mixtures traveling through cell membranes or moving through artificial nanopores, for the controlling transport in colloidal suspensions, and for the particle separation.In conclusion, we numerically studied the transport of mixtures of active and passive particles moving in a periodic channel with a M-shaped barrier. A big passive particle was immersed in the ‘sea’ of active particles. The longitudinal ratchet transport of particles can be induced by the transversal asymmetry. The interactions from chiral active particles can make the passive particle move directionally. For active particles, the direction of the ratchet transport is completely determined by the chirality of active particles, the average velocity is positive for Ω < 0, zero at Ω = 0 and negative for Ω > 0. In other words, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, the transport behavior of the passive particle becomes complicated, the direction of the ratchet transport is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Remarkably, within certain parameters, the passive and active particles move to the opposite directions, for example, the big passive particle moves to the left, while active particles move to the right when Ω = −0.01 and How to cite this article: Ai, B.-q. Ratchet transport powered by chiral active particles. Sci. Rep.6, 18740; doi: 10.1038/srep18740 (2016).