Selective recognition of pyrophosphate in water using a backbone modified cyclic peptide receptor

A cyclic peptide based receptor, bearing two dipicolylamino arms complexed to zinc(II) ions, binds pyrophosphate ions with high affinity and selectivity in aqueous solution as determined using an indicator displacement assay.     

Regio- and diastereocontrolled C-H insertion of chiral gamma- and delta-lactam diazoacetates. Application to the asymmetric synthesis of (8S,8aS)-8-hydroxyindolizidine

gamma- and delta-Lactam diazoacetates undergo efficient intramolecular C-H insertion catalyzed by Rh2(MPPIM)4 with excellent regioselectivity and cis-diastereoselectivity to provide synthetically useful bicyclic lactam lactones.     

Effect of functional group (fluorine) of aromatic thiols on electron transfer at the molecule-metal interface

Electron transfer at the molecule-metal interface of self-assembled monolayers of 1,1';4',1'-terphenyl-4'-thiol (BBB) and its partially fluorinated counterpart (BFF: p-thiophenyl-nonafluorobiphenyl) on Au(111) is investigated by core-hole clock spectroscopy. Ultrafast electron transfer at the BBB/Au(111) interface in the low-femtosecond regime (on the same time scale as the C 1s core-hole lifetime, approximately 6 fs) was observed. In contrast, for BFF/Au(111), the interface electron transfer was forbidden during the core-hole decay. This strongly suggests that fluorination of phenyl rings significantly enhances the localization of the excited electrons in the LUMO.     

Creating polymer structures of tunable electric functionality by nanoscale discharge-assisted cross-linking and oxygenation

We report the creation of polymeric micro/nanostructures which exhibit distinct chemical and physical characteristics from the matrix poly(N-vinyl carbazole) (PVK). The structure formation is based on atomic force microscopy (AFM) facilitated cross-linking and oxygenation. The reaction of PVK with AFM lithographically induced nanoscale discharge produces raised structures in which bridge oxygen links neighboring carbazole groups. The cross-linking by bridge oxygen converts the initially insulating PVK matrix to chemically modified conducting patterns through the formation of extended pi-conjugations. A comprehensive AFM, PES (photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), and DFT (density functional theory) analysis is presented to address the chemophysical identity of the patterned structures. Our results demonstrate new capabilities of AFM nanolithography in generating heterogeneous functional structures in a polymer matrix.     

A Representation Stability Theorem for VI-modules

Let VI be the category whose objects are the finite dimensional vector spaces over a finite field of order q and whose morphisms are the injective linear maps. A VI-module over a ring is a functor from the category VI to the category of modules over the ring. A VI-module gives rise to a sequence of representations of the finite general linear groups. We prove that the sequence obtained from any finitely generated VI-module over an algebraically closed field of characteristic zero is representation stable - in particular, the multiplicities which appear in the irreducible decompositions eventually stabilize. We deduce as a consequence that the dimension of the representations in the sequence {V _n } obtained from a finitely generated VI-module V over a field of characteristic zero is eventually a polynomial in q ⁿ . Our results are analogs of corresponding results on representation stability and polynomial growth of dimension for FI-modules (which give rise to sequences of representations of the symmetric groups) proved by Church, Ellenberg, and Farb.     

Improved,black-box,non-malleable encryption from semantic security

We give a new black-box transformation from any semantically secure encryption scheme into a non-malleable one which has a better rate than the best previous work of Coretti et al. (in: Kushilevitz and Malkin (eds) TCC 2016-A, Part I, Springer, Heidelberg, 2016). We achieve a better rate by departing from the “matrix encoding” methodology used by previous constructions, and working directly with a single codeword. We also use a Shamir secret-share packing technique to improve the rate of the underlying error-correcting code.     

Exact Convergence Rate for the Distributions of GI/M/c/K Queue as K Tends to Infinity

We obtain the exact convergence rate of the stationary distribution ^(K) of the embedded Markov chain in GI/M/c/K queue to the stationary distribution of the embedded Markov chain in GI/M/c queue as K. Similar result for the time-stationary distributions of queue size is also included. These generalize Choi and Kim's results of the case c=1 by nontrivial ways. Our results also strengthen the Simonot's results [5].     

Can radical cations of the constituents of nucleic acids be formed in the gas phase using ternary transition metal complexes?

Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary transition metal complexes of [M(L(3))(N)](2+) (where M = copper(II) or platinum(II); L(3) = diethylenetriamine (dien) or 2,2':6',2'-terpyridine (tpy); N = the nucleobases: adenine, guanine, thymine and cytosine; the nucleosides: 2'deoxyadenosine, 2'deoxyguanosine, 2'deoxythymine, 2'deoxycytidine; the nucleotides: 2'deoxyadenosine 5'-monophosphate, 2'deoxyguanosine 5'-monophosphate, 2'deoxythymine 5'-monophosphate, 2'deoxycytidine 5'-monophosphate) was examined as a means of forming radical cations of the constituents of nucleic acids in the gas phase. In general, sufficient quantities of the ternary complexes [M(L(3))(N)](2+) could be formed for MS/MS studies by subjecting methanolic solutions of mixtures of a metal salt [M(L(3))X(2)] (where M = Cu(II) or Pt(II); L(3) = dien or tpy; X = Cl or NO(3)) and N to ESI. The only exceptions were thymine and its derivatives, which failed to form sufficient abundances of [M(L(3))(N)](2+) ions when: (a) M = Pt(II) and L(3) = dien or tpy; (b) M = Cu(II) and L(3) = dien. In some instances higher oligomeric complexes were formed; e.g., [Pt(tpy)(dG)(n)](2+) (n = 1-13). Each of the ternary complexes [M(L(3))(N)](2+) was mass-selected and then subjected to collision-induced dissociation (CID) in a quadrupole ion trap. The types of fragmentation reactions observed for these complexes depend on the nature of all three components (metal, auxiliary ligand and nucleic acid constituent) and can be classified into: (i) a redox reaction which results in the formation of the radical cation of the nucleic acid constituent, N(+.); (ii) loss of the nucleic acid constituent in its protonated form; and (iii) fragmentation of the nucleic acid constituent. Only the copper complexes yielded radical cations of the nucleic acid constituent, with [Cu(tpy)(N)](2+) being the preferred complex due to suppression, in this case, of the loss of the nucleobase in its protonated form. The yields of the radical cations of the nucleobases from the copper complexes follow the order of their ionization potentials (IPs): G (lowest IP) > A > C > T (highest IP). Sufficient yields of the radical cations of each of the nucleobases allowed their CID reactions (in MS(3) experiments) to be compared to their even-electron counterparts.