Form-factors and current correlators: chiral couplings L_10(mu) and C_87(mu) at NLO in 1/N(C)

Using the resonance chiral theory Lagrangian, we perform a calculation of the vector and axial-vector two-point functions at the next-to-leading order (NLO) in the 1/N(C) expansion. We have analyzed these correlators within the single-resonance approximation and have also investigated the corrections induced by a second multiplet of vector and axial-vector resonance states. Imposing the correct QCD short-distance constraints, one determines the difference of the two correlators Pi(t) = Pi_VV(t)- Pi_AA(t) in terms of the pion decay constant and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L_10 and C_87 at NLO, keeping full control of their renormalization scale dependence. At mu_0=0.77 GeV, we obtain L_10(mu_0) = (-4.4 \pm 0.9)10^{-3} and C_87^r(mu_0)=(3.1 \pm 1.1)10^{-5}

Multiscale Modelling of Lytic Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenase (LPMO) enzymes have attracted considerable attention due to their ability to enhance polysaccharide depolymerization, making them interesting in respect to production of biofuel from cellulose. The LPMOs are metalloenzymes that contain a mononuclear copper active site that can active dioxygen. However, many details of this activation are unclear, and have previously been investigated from a computational angle. Yet, these studies have either employed only molecular mechanics (MM), which are inaccurate for metal active sites, or they have described only the active site with quantum mechanics (QM) and neglected the effect of the protein. Here, we employ hybrid QM and MM (QM/MM) methods to investigate the first steps of the LPMO mechanism, which is reduction of of Cu(II) to Cu(I) and formation of a Cu(II)-superoxide complex. In the latter complex, the superoxide can bind either in an equatorial or an axial position. For both steps we obtain structures that are markedly different from previous suggestions, based on vacuum calculations. Our calculations show that the equatorial isomer of the superoxide complex is over 60 kJ/mol more stable than the axial isomer, being stabilized by interactions with a second-coordination-sphere Gln residue, showing a possible role for this residue. Coordination of superoxide in this manner is in agreement with recent experimental suggestions.Comment: 21 pages, 6 figures, 3 tables. 20 pages Supporting Informatio

The Structure of Qubit Unextendible Product Bases

Unextendible product bases have been shown to have many important uses in quantum information theory, particularly in the qubit case. However, very little is known about their mathematical structure beyond three qubits. We present several new results about qubit unextendible product bases, including a complete characterization of all four-qubit unextendible product bases, which we show there are exactly 1446 of. We also show that there exist p-qubit UPBs of almost all sizes less than $2^p$.Comment: 20 pages, 3 tables, 7 figure

Dynamic equilibrium correction modelling of yen Eurobond credit spreads

Understanding the long term relationship between the yields of risky and riskless bonds is a critical task for portfolio managers and policy makers. This study specifies an equilibrium correction model of the credit spreads between Japanese Government bonds (JGBs) and Japanese yen Eurobonds with high quality credit ratings. The empirical results indicate that the corporate bond yields are cointegrated with the otherwise equivalent JGB yields, with the spread defining the cointegration relation. In addition the results indicate that the equilibrium correction term is highly statistically significant in modelling credit spread changes. Another important factor is the risk-free interest rate with the negative sign, while there is little evidence of the contribution of the asset return to the behaviour of spreads.

Discovery and characterization of a new family of lytic polysaccharide monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are a recently discovered class of enzymes capable of oxidizing recalcitrant polysaccharides. They are attracting considerable attention owing to their potential use in biomass conversion, notably in the production of biofuels. Previous studies have identified two discrete sequence-based families of these enzymes termed AA9 (formerly GH61) and AA10 (formerly CBM33). Here, we report the discovery of a third family of LPMOs. Using a chitin-degrading exemplar from Aspergillus oryzae, we show that the three-dimensional structure of the enzyme shares some features of the previous two classes of LPMOs, including a copper active center featuring the 'histidine brace' active site, but is distinct in terms of its active site details and its EPR spectroscopy. The newly characterized AA11 family expands the LPMO clan, potentially broadening both the range of potential substrates and the types of reactive copper-oxygen species formed at the active site of LPMOs

CaCO₃ mineralization in polymer composites with cellulose nanocrystals providing a chiral nematic mesomorphic structure

CaCO₃ mineralization was carried out using cellulose nanocrystal (CNC)/polymer composites wherein a chiral nematic structure of CNC assembly was immobilized in advance via a polymerization process of the precursory aqueous CNC/vinyl monomer lyotropics (7–11 wt% CNC in feed). Two series of polymer composites were prepared: CNC/poly(2-hydroxyethyl methacrylate) (PHEMA) and CNC/poly(2-hydroxyethyl methacrylate-co-acrylic acid) (P(HEMA-co-AA), HEMA:AA = 95:5–70:30 in mol). The mineralization was allowed to proceed solely by soaking the composite films in a salt solution containing Ca²⁺ and HCO₃− under a low-basic condition (pH ≤ 9). Polymorphism of CaCO3 deposited inside the films was examined by X-ray diffractometry as a function of the soaking time (1–5 day) and also of the matrix composition. In the CNC/PHEMA series, the polymorphic form changed from amorphous calcium carbonate (ACC) (1-day soaking) to metastable crystalline vaterite (3-day soaking) and then to a mixture of vaterite and aragonite (5-day soaking). In the mineralization of the CNC/P(HEMA-co-AA) series, the formation of stable calcite was prominent besides minor appearance of vaterite. It was deduced that the mesofiller CNC and the AA unit in the vinyl polymer, both bearing an anionic group (-SO₃− or -COO−), contributed to capturing Ca²⁺ to facilitate the CaCO₃ deposition in the swollen film matrix. The pre-invested chiral nematic organization was kept in any of the mineralized films (dried); however, the helical pitch was appreciably reduced relative to that observed before the mineralization, attributable to the increase of ionic strength in the CNCs' surroundings accompanied by the wet process. Thermogravimetry showed that the mineralization definitely improved the thermal performance (heat/flame resistance) of the mesomorphic order-retaining CNC/polymer composites

Immunization with lytic polysaccharide monooxygenase CbpD induces protective immunity against Pseudomonas aeruginosa pneumonia

publishedVersio

Lytic polysaccharide monooxygenases:a crystallographer's view on a new class of biomass-degrading enzymes

Lytic polysaccharide monooxygenases (LPMOs) are a new class of microbial copper enzymes involved in the degradation of recalcitrant polysaccharides. They have only been discovered and characterized in the last 5–10 years and have stimulated strong interest both in biotechnology and in bioinorganic chemistry. In biotechnology, the hope is that these enzymes will finally help to make enzymatic biomass conversion, especially of lignocellulosic plant waste, economically attractive. Here, the role of LPMOs is likely to be in attacking bonds that are not accessible to other enzymes. LPMOs have attracted enormous interest since their discovery. The emphasis in this review is on the past and present contribution of crystallographic studies as a guide to functional understanding, with a final look towards the future

Potensi Isolat Bakteri Endofit Akar Tanaman Bawang Merah (Allium ascalonium) sebagai Bakteri Pelarut Fosfat

Lima isolat bakteri endofit telah ditemukan dari akar tanaman bawang merah yaitu isolat AA2, AA7, AA8, AA9, dan AA10 dan menunjukkan adanya fermentasi asam organik sebagai indikasi bakteri dapat melarutkan fosfat. Penelitian ini bertujuan untuk mendeskripsikan potensi lima isolat bakteri endofit dari akar tanaman bawang merah (Allium ascalonium) dalam melarutkan fosfat dan menjelaskan hubungan antara jumlah sel bakteri dengan konsentrasi fosfat yang dilarutkan. Penelitian ini bersifat observasional dengan parameter yang dianalisis secara kualitatif berupa rata-rata indeks pelarut fosfat (IPF), secara kuantitatif berupa konsentrasi fosfat diukur dengan spektrofotometer pada panjang gelombang 830 nm, jumlah bakterinya dihitung dengan haemocytometer dan pH diukur dengan pH meter. Hasil penelitian menunjukan nilai IPF secara berturut-turut sebesar 1,22; 1,71; 1,36; 1,42 dan 1,37 untuk isolat AA2, AA7, AA8, AA9 dan AA10. Isolat bakteri AA2 memiliki konsentrasi fosfat terlarut paling besar yaitu sebesar 63,016 ppm pada hari ke-5 masa inkubasi dengan jumlah bakteri sebesar 7,9 x 107 sel/ml. Hubungan jumlah bakteri dengan konsentrasi fosfat terlarut terjadi pada saat jumlah bakteri mencapai jumlah optimal sedangkan konsentrasi fosfat terlarut mengalami penurunan pada hari ke-3 masa inkubasi