A Porous Sulfonated 2D Zirconium Metal–Organic Framework as a Robust Platform for Proton Conduction

By using the strategy of pre-assembly chlorosulfonation applied to a linker precursor, the first sulfonated zirconium metal–organic framework ( JUK-14 ) with two-dimensional (2D) structure, was synthesized. Single-crystal X-ray diffraction reveals that the material is built of Zr₆O₄(OH)₄(COO)₈ oxoclusters, doubly 4-connected by angular dicarboxylates, and stacked in layers spaced 1.5 nm apart by the presence of sulfonic groups. JUK-14 exhibits excellent hydrothermal stability, permanent porosity confirmed by gas adsorption studies, and shows high (>10⁻⁴ S/cm) and low (<10⁻⁸ S/cm) proton conductivity under humidified and anhydrous conditions, respectively. Post-synthesis inclusion of imidazole improves the overall conductivity increasing it to 1.7×10⁻³ S/cm at 60 °C and 90 % relative humidity, and by 3 orders of magnitude at 160 °C. The combination of 2D porous nature with robustness of zirconium MOFs offers new opportunities for exploration of the material towards energy and environmental applications.     

On a nonlinear boundary value problem modeling corneal shape

In this paper we present some results concerning a boundary value problem for a nonlinear ordinary differential equation that was used before in modeling the topography of human cornea. These results generalize previously obtained theorems on existence and uniqueness. We show that our equation has a unique solution for all parameters and conditions that can arise in physical situation. In the second part of the article we derive some new estimates and approximate solutions. Numerical calculations verify that these approximations are very accurate.     

The investigation of femoroacetabular impingement using motion capture,FEM and multi-body simulations

In recent years, femoroacetabular impingement (FAI) has become increasingly common. As published in the literature, FAI is caused by an unphysiological contact between the proximal femur and the acetabular rim, which may lead to pain, limitation of movement, and damage of cartilage. In this paper, patient-specific finite element simulations of the movement of the hip based on gait motion data and MRI segmentation were conducted to check stresses of the acetabulum and femur, and additionally whether a bony contact is present or not. The study's findings show no bony contact between femur and acetabulum, which may lead to the hypothesis that the labrum and its deformation and/or the articular capsule are involved in the mechanism of FAI. In order to verify this hypothesis more simulations including labrum and capsule must be performed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mechanism of Formation of Ribonucleoside Cyclic 2′,3′-Phosphates in the Reaction of Appropriate 3′,5′-Phos-Phorothioates with Epoxides

Abstract

It has been recently demonstrated in our laboratory CD that ribonucleoside cyclic 3′,5′-phosphorothioates react with epoxides to give as a major product corresponding cyclic 5′,3′-phosphates, We now report the results OF our ste-reochemical studies OF this reaction. WE have Found that the diastereomerically pure (Sp) 3′.5′-CUFLPS when treated with styrene [¹⁰O]-oxide in ethanol gives the same isotopomer OF 2′,3′-[¹⁰O]cUMP as that obtained From the reaction of endo-2′.3′-cUMPS with styrene [¹⁰O]-oxide. This result strongly supports our previous assumption that reaction of 3′,5′-cNMPS with epoxides proceeds via 3′-oxathiaphosphorylated intermediate (L) which is Formed with inversion and decomposes to 2′,3′-cNMP with retention of configuration at phosphorus atom.     

Dinucleoside (5′ → 3′)-O,S-Phosphorodithioates - New Class of Dinucleotide Analogues

Abstract

Nucleoside 3′-0- and 5′-O-phosphorodithioates have been recently described by Caruthers et al.¹ as a new type of nucleotide analogues. These compounds have also been obtained in our Laboratory by one-pot dithiaphospholane approach.² We now report on the transformation of some of these derivatives into new class of dinucleotide analogues. We have found that nucleoside 3′-O-phosphorodithioates (1) react in DMF solution with 5′-bromo-5′-deoxythymidine to give in high yield corresponding dinucleoside (5′→3′)-O,S-phosphorodithioates (2) - first examples of a new class of dinucleotide analogues possessing the internucleotide phosphorothioate linkage with one of the sulfur atoms in a 3′-bridging position.     

15N NMR Study of the P-N Bonding in Phosphoric Amides

Abstract

A series of phosphoric amidodiesters, diamidoesters and triamides was prepared and their ³¹P and¹⁵ N NMR spectra were recorded in order to evaluate the major structural factors that determine the chemical shifts and coupling contants values. Considering the equation expressing the structural effects on shielding^[1].     

Strategy of Cr detoxification by Callitriche cophocarpa

The present work focused on the qualitative and quantitative analysis of Cr detoxification strategy of aquatic cosmopolitan plant Callitriche cophocarpa. This plant species has just been described in the context of its unusual accumulation potential of Cr. The emphasis of the work was placed on the redox reaction Cr(VI)→Cr(III) which is considered to be remediation mechanism of highly reactive and mobile Cr(VI) ions. Plants were immersed for 5 days in 1 mM of Cr(VI) (potassium dichromate) or 1 mM of Cr(III) (chromium sulphate) solutions in semi-natural conditions. Cr was effectively removed from the solution up to the extent of ca.58% or 35% of the starting amount, in the case of Cr(III) and Cr(VI), respectively. No plant-induced Cr(VI) reduction accompanying Cr accumulation was observed in Cr(VI) solutions except from the apparent one, noticed at the fourth day of incubation. On the contrary to these results, according to the method of electron paramagnetic resonance spectroscopy (L-band EPR), biphasic signal of Cr(V) attending Cr(VI) to Cr(III) reduction was detected inside the plant tissue every day of investigations. Our results show that phytoextraction but not phytostabilization is the main strategy of Cr detoxification by C. cophocarpa in aquatic systems.      

Performance of density functional theory in computing nonresonant vibrational (hyper)polarizabilities

A set of exchange‐correlation functionals, including BLYP, PBE0, B3LYP, BHandHLYP, CAM‐B3LYP, LC‐BLYP, and HSE, has been used to determine static and dynamic nonresonant (nuclear relaxation) vibrational (hyper)polarizabilities for a series of all‐trans polymethineimine (PMI) oligomers containing up to eight monomer units. These functionals are assessed against reference values obtained using the Møller–Plesset second‐order perturbation theory (MP2) and CCSD methods. For the smallest oligomer, CCSD(T) calculations confirm the choice of MP2 and CCSD as appropriate for assessing the density functionals. By and large, CAM‐B3LYP is the most successful, because it is best for the nuclear relaxation contribution to the static linear polarizability, intensity‐dependent refractive index second hyperpolarizability, static second hyperpolarizability, and is close to the best for the electro‐optical Pockels effect first hyperpolarizability. However, none of the functionals perform satisfactorily for all the vibrational (hyper)polarizabilities studied. In fact, in the case of electric field‐induced second harmonic generation all of them, as well as the Hartree–Fock approximation, yield the wrong sign. We have also found that the Pople 6–31+G(d) basis set is unreliable for computing nuclear relaxation (hyper)polarizabilities of PMI oligomers due to the spurious prediction of a nonplanar equilibrium geometry. © 2013 Wiley Periodicals, Inc.