Structure investigation of fluorinated aluminophosphate ULM-3 Al templated by 3-methylaminopropylamine

A single-crystal X-ray diffraction analysis of an open-framework aluminophosphate ULM-3 Al prepared by 3-methylaminopropylamine (MAPA) as structure-directing agent revealed an orthorhombic Pcab symmetry (a=9.9949(4) Å, b=15.8229(7) Å, c=18.1963(5) Å, R=0.0648, Z=8, unit cell formula [Al₂₄P₂₄O₉₆F₁₆·C₃₂H₁₁₂N₁₆]), which differs from the Pbc2₁ symmetry of the structural analogue prepared in the presence of 1,4-diaminobutane. The ²⁷Al, ³¹P, ¹⁹F, ¹³C and ¹H NMR investigations, which were performed to study in detail MAPA arrangement inside the framework as well as the interactions of MAPA with the aluminophosphate host, confirmed the crystal symmetry and the proposed hydrogen bonding scheme between the template and the framework.     

Switching mechanism in polar columnar mesophases made of bent-core molecules.

The behaviour of polar, broken-layer-type columnar phases made of bent molecules (B(1Rev) and B(1RevTilted)) was studied under an applied electric field. There are two competing mechanisms of ferroelectric switching in the polar B(1RevTilted) columnar phase: collective rotation around the long molecular axis and collective rotation around the tilt cone. The proposed model shows that the main factor discriminating the type of switching is the width of the column cross-section.     

On Gradient Ricci Solitons

In the first part of the paper we derive integral curvature estimates for complete gradient shrinking Ricci solitons. Our results and the recent work in M. Fernandez-Lopez and E. Garcia-Rio, Rigidity of shrinking Ricci solitons in Math. Z. (2011) classify complete gradient shrinking Ricci solitons with harmonic Weyl tensor. In the second part of the paper we address the issue of existence of harmonic functions on gradient shrinking Kähler and gradient steady Ricci solitons. Consequences to the structure of shrinking and steady solitons at infinity are also discussed.     

Microwave-Assisted Extraction Coupled to HPLC-UV Combined with Chemometrics for the Determination of Bioactive Compounds in Pistachio Nuts and the Guarantee of Quality and Authenticity

Two novel microwave-assisted extraction (MAE) methods were developed for the isolation of phenols and tocopherols from pistachio nuts. The extracts were analyzed by reversed-phase high-pressure liquid chromatography coupled with a UV detector (RP-HPLC-UV). In total, eighteen pistachio samples, originating from Greece and Turkey, were analyzed and thirteen phenolic compounds, as well as α-tocopherol, (β + γ)-tocopherol, and δ-tocopherol, were identified. The analytical methods were validated and presented good linearity (r² > 0.990) and a high recovery rate over the range of 82.4 to 95.3% for phenols, and 93.1 to 96.4% for tocopherols. Repeatablility was calculated over the range 1.8–5.8%RSD for intra-day experiments, and reproducibility over the range 3.2–9.4%RSD for inter-day experiments, respectively. Principal component analysis (PCA) was employed to analyze the differences between the concentrations of the bioactive compounds with respect to geographical origin, while agglomerative hierarchical clustering (AHC) was used to cluster the samples based on their similarity and according to the geographical origin.     

Examples of Möbius-like groups which are not Möbius groups

In this paper we give two basic constructions of groups with the following properties:

(a)

, i.e., the group is acting by orientation preserving homeomorphisms on ;

(b)

every element of is Möbius-like;

(c)

, where denotes the limit set of ;

(d)

is discrete;

(e)

is not a conjugate of a Möbius group.

Both constructions have the same basic idea (inspired by Denjoy): we start with a Möbius group (of a certain type) and then we change the underlying circle upon which acts by inserting some closed intervals and then extending the group action over the new circle. We denote this new action by . Now we form a new group which is generated by all of and an additional element whose existence is enabled by the inserted intervals. This group has all the properties (a) through (e).

     

A study of the kinetics of isothermal nicotine desorption from silicon dioxide

The isothermal kinetics of nicotine desorption from silicon dioxide (SiO₂) was investigated. The isothermal thermogravimetric curves of nicotine at temperatures of 115 °C, 130 °C and 152 °C were recorded. The kinetic parameters (E_a, ln A) of desorption of nicotine were calculated using various methods (stationary point, model constants and differential isoconversion method). By applying the “model-fitting” method, it was found that the kinetic model of nicotine desorption from silicon dioxide was a phase boundary controlled reaction (contracting volume). The values of the kinetic parameters, E_a,α and ln A_α, complexly change with changing degree of desorption and a compensation effect exists. A new mechanism of activation for the desorption of the absorbed molecules of nicotine was suggested in agreement with model of selective energy transfer.     

On the extension of the mean curvature flow

Consider a family of smooth immersions ${F(\cdot,t): M^n\to \mathbb{R}^{n+1}}$ of closed hypersurfaces in ${\mathbb{R}^{n+1}}$ moving by the mean curvature flow ${\frac{\partial F(p,t)}{\partial t} = -H(p,t)\cdot \nu(p,t)}$ , for ${t\in [0,T)}$ . Cooper (Mean curvature blow up in mean curvature flow, arxiv.org/abs/0902.4282) has recently proved that the mean curvature blows up at the singular time T. We show that if the second fundamental form stays bounded from below all the way to T, then the scaling invariant mean curvature integral bound is enough to extend the flow past time T, and this integral bound is optimal in some sense explained below.     

A new layered Ca–succinate coordination polymer

A new layered Ca–succinate coordination polymer, poly[μ₃‐succinato‐calcium(II)], [Ca(C₄H₅O₄)]_n, was synthesized by reaction of CaCl₂·2H₂O and succinic acid in an aqueous medium under hydrothermal microwave conditions. The structure contains infinite layers of edge‐sharing calcium pentagonal–bipyramidal polyhedra forming six‐membered rings connected through succinate ligands. Such an assembly of inorganic building units is unique for calcium metal–organic framework‐type structures. Adjacent layers are packed into a final pseudo‐three‐dimensional structure through weak C—H...O hydrogen bonds.     

Synthetic Tigliane Intermediates Engage Thiols to Induce Potent Cell Line Selective Anti-Cancer Activity

The tigliane ring system, which encompasses iconic members such as phorbol and TPA, is widely renowned due to numerous observations of displaying potent biological activity, and subsequent use as mainstream biochemical tools. Traditionally, naturally occurring phorboids are regarded as tumor promotors through PKC activation, although in recent times more highly oxidized natural derivatives have been identified as anti-tumor agents. In the view that only limited synthetic investigations toward skeletal stereochemical modification have been undertaken, non-natural systems could be useful for a better understanding of the tigliane pharmacophore via interrogation of cellular sensitivity. In this context the concise construction of a number of highly functionalized non-natural D-ring inverted phorbol esters were synthesized, via a rhodium-catalyzed [4+3] cycloaddition, and biologically evaluated using a range of cancer cell lines. The biological results highlight the notion that subtle changes in structure have dramatic effects on potency. Furthermore, although the non-natural derivatives did not outcompete the natural systems in the PKC-activation sensitive MCF7 cancer cell line, they outperformed in other cancer cell lines (MM96L and CAL27). This observation strongly suggested an alternate mode of action not involving activation of PKC, but instead involves thiol addition as indicated by glutathione addition and NF-κB reporter activity.