Key-to-lock halogen bond-based tetragonal pyramidal association of iodonium cations with the lacune rims of beta-octamolybdate.

The structure-directing "key-to-lock" interaction of double σ-(I)-hole donating iodonium cations with the O-flanked pseudo-lacune rims of [β-MoO] gives halogen-bonded iodonium-beta-octamolybate supramolecular associates. In the occurrence of their tetragonal pyramidal motifs, deep and broad σ-(I)-holes of a cation recognize the molybdate backbone, which provides an electronic pool localized around the two lacunae. The halogen-bonded I⋯O linkages in the structures were thoroughly studied computationally and classified as two-center, three-center bifurcated, and unconventional "orthogonal" I⋯O halogen bonds.

Capillary condensation between nonparallel walls.

We study the condensation of fluids confined by a pair of nonparallel plates of finite height H. We show that such a system experiences two types of condensation, termed single and double pinning, which can be characterized by one (single-pinning) or two (double-pinning) edge contact angles describing the shape of menisci pinned at the system edges. For both types of capillary condensation, we formulate the Kelvin-like equation and determine the conditions under which the given type of condensation occurs.

Development of Prolinol Containing Inhibitors of Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferase: Rational Structure-Based Drug Design.

Inhibition of hypoxanthine-guanine-xanthine phosphoribosyltransferase activity decreases the pool of 6-oxo and 6-amino purine nucleoside monophosphates required for DNA and RNA synthesis, resulting in a reduction in cell growth. Therefore, inhibitors of this enzyme have potential to control infections, caused by and , , , and . Five compounds synthesized here that contain a purine base covalently linked by a prolinol group to one or two phosphonate groups have values ranging from 3 nM to >10 μM, depending on the structure of the inhibitor and the biological origin of the enzyme.

Kelvin equation for bridging transitions.

We study bridging transitions between a pair of nonplanar surfaces. We show that the transition can be described using a generalized Kelvin equation by mapping the system to a slit of finite length. The proposed equation is applied to analyze the asymptotic behavior of the growth of the bridging film, which occurs when the confining walls are gradually flattened.

Critical-point wedge filling and critical-point wetting.

For simple fluids adsorbed at a planar solid substrate (modeled as an inert wall) it is known that critical-point wetting, that is, the vanishing of the contact angle θ at a temperature T_{w} lying below that of the critical point T_{c}, need not occur. While critical-point wetting necessarily happens when the wall-fluid and fluid-fluid forces have the same range (e.g.

Critical behaviour of the contact angle within nonwetting gaps.

Recent density functional theory and simulation studies of fluid adsorption near planar walls in systems where the wall-fluid and fluid-fluid interactions have different ranges, have shown that critical point wetting may not occur and instead nonwetting gaps appear in the surface phase diagram, separating lines of wetting and drying transitions, that extend up to the critical temperature. Here we clarify the features of the surface phase diagrams that are common, regardless of the range and balance of the forces, showing, in particular, that the lines of temperature driven wetting and drying transitions, as well as lines of constant contact angleπ>θ>0, always converge to an ordinary surface phase transition at. When nonwetting gaps appear the contact angle either vanishes or tends toast≡(Tc-T)/Tc→0.

Surface Phase Diagrams for Wetting with Long-Ranged Forces.

Recent density functional theory and simulation studies of wetting and drying transitions in systems with long-ranged, dispersionlike forces, away from the near vicinity of the bulk critical temperature T_{c}, have questioned the generality of the global surface phase diagrams for wetting, due to Nakanishi and Fisher, pertinent to systems with short-ranged forces. We extend these studies deriving fully analytic results which determine the surface phase diagrams over the whole temperature range up to T_{c}. The phase boundaries, order of, and asymmetry between the lines of wetting and drying transitions are determined exactly showing that they always converge to an ordinary surface critical point.

Co-Pyrolysis of Unsaturated C4 and Saturated C6+ Hydrocarbons-An Experimental Study to Evaluate Steam-Cracking Performance.

Unsaturated C4 hydrocarbons are abundant in various petrochemical streams. They can be considered as a potential feedstock for the steam-cracking process, where they must be co-processed with C6 and higher (C6+) hydrocarbons of primary naphtha fractions. Co-pyrolysis experiments aiming at the comparison of different C4 hydrocarbon performances were carried out in a laboratory micro-pyrolysis reactor under standardized conditions: 820 °C, 400 kPa, and 0.

Critical effects and scaling at meniscus osculation transitions.

We propose a simple scaling theory describing critical effects at rounded meniscus osculation transitions which occur when the Laplace radius of a condensed macroscopic drop of liquid coincides with the local radius of curvature R_{w} in a confining parabolic geometry. We argue that the exponent β_{osc} characterizing the scale of the interfacial height ℓ_{0}∝R_{w}^{β_{osc}} at osculation, for large R_{w}, falls into two regimes representing fluctuation-dominated and mean-field-like behavior, respectively. These two regimes are separated by an upper critical dimension, which is determined here explicitly and depends on the range of the intermolecular forces.

Phase behavior of fluids in undulated nanopores.

The geometry of walls forming a narrow pore may qualitatively affect the phase behavior of the confined fluid. Specifically, the nature of condensation in nanopores formed of sinusoidally shaped walls (with amplitude A and period P) is governed by the wall mean separation L as follows. For L>L_{t}, where L_{t} increases with A, the pores exhibit standard capillary condensation similar to planar slits.

Capillary condensation and depinning transitions in open slits.

We study the low-temperature phase equilibria of a fluid confined in an open capillary slit formed by two parallel walls separated by a distance L which are in contact with a reservoir of gas. The top wall of the capillary is of finite length H while the bottom wall is considered of macroscopic extent. This system shows rich phase equilibria arising from the competition between two different types of capillary condensation, corner filling, and meniscus depinning transitions depending on the value of the aspect ratio a=L/H and divides into three regimes: For long capillaries, with a<2/π, the condensation is of type I involving menisci which are pinned at the top edges at the ends of the capillary.

Edge Contact Angle, Capillary Condensation, and Meniscus Depinning.

We study the phase equilibria of a fluid confined in an open capillary slit formed when a wall of finite length H is brought a distance L away from a second macroscopic surface. This system shows rich phase equilibria arising from the competition between two different types of capillary condensation, corner filling and meniscus depinning transitions depending on the value of the aspect ratio a=L/H. For long capillaries, with a<2/π, the condensation is of type I involving menisci which are pinned at the top edges at the ends of the capillary characterized by an edge contact angle.

Breaking Cassie's Law for Condensation in a Nanopatterned Slit.

We study the phase transitions of a fluid confined in a capillary slit made from two adjacent walls, each of which are a periodic composite of stripes of two different materials. For wide slits the capillary condensation occurs at a pressure which is described accurately by a combination of the Kelvin equation and the Cassie law for an averaged contact angle. However, for narrow slits the condensation occurs in two steps involving an intermediate bridging phase, with the corresponding pressures described by two new Kelvin equations.

Height of a liquid drop on a wetting stripe.

Adsorption of liquid on a planar wall decorated by a hydrophilic stripe of width L is considered. Under the condition that the wall is only partially wet (or dry) while the stripe tends to be wet completely, a liquid drop is formed above the stripe. The maximum height ℓ_{m}(δμ) of the drop depends on the stripe width L and the chemical potential departure from saturation δμ where it adopts the value ℓ_{0}=ℓ_{m}(0).

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates.

We study adsorption at periodically corrugated substrates formed by scoring rectangular grooves into a planar solid wall which interacts with the fluid via long-range (dispersion) forces. The grooves are assumed to be macroscopically long but their depth, width, and separations can all be molecularly small. We show that the entire adsorption process can be divided into three parts consisting of (i) filling the grooves by a capillary liquid; (ii) depinning of the liquid-gas interface from the wall edges; and (iii) unbinding of the interface from the top of the wall, which is accompanied by a rapid but continuous flattening of its shape.

Three-Phase Fluid Coexistence in Heterogenous Slits.

We study the competition between local (bridging) and global condensation of fluid in a chemically heterogeneous capillary slit made from two parallel adjacent walls each patterned with a single stripe. Using a mesoscopic modified Kelvin equation, which determines the shape of the menisci pinned at the stripe edges in the bridge phase, we determine the conditions under which the local bridging transition precedes capillary condensation as the pressure (or chemical potential) is increased. Provided the contact angle of the stripe is less than that of the outer wall we show that triple points, where evaporated, locally condensed, and globally condensed states all coexist are possible depending on the value of the aspect ratio a=L/H, where H is the stripe width and L the wall separation.

Symmetry-breaking morphological transitions at chemically nanopatterned walls.

We study the structure and morphological changes of fluids that are in contact with solid composites formed by alternating and microscopically wide stripes of two different materials. One type of the stripes interacts with the fluid via long-ranged Lennard-Jones-like potential and tends to be completely wet, while the other type is purely repulsive and thus tends to be completely dry. We consider closed systems with a fixed number of particles that allows for stabilization of fluid configurations breaking the lateral symmetry of the wall potential.

Scaling of wetting and prewetting transitions on nanopatterned walls.

We consider a nanopatterned planar wall consisting of a periodic array of stripes of width L, which are completely wet by liquid (contact angle θ=0), separated by regions of width D which are completely dry (contact angle θ=π). Using microscopic density functional theory, we show that, in the presence of long-ranged dispersion forces, the wall-gas interface undergoes a first-order wetting transition, at bulk coexistence as the separation D is reduced to a value D_{w}∝lnL, induced by the bridging between neighboring liquid droplets. Associated with this is a line of prewetting transitions occurring off coexistence.

Driving Cells with Light-Controlled Topographies.

Cell-substrate interactions can modulate cellular behaviors in a variety of biological contexts, including development and disease. Light-responsive materials have been recently proposed to engineer active substrates with programmable topographies directing cell adhesion, migration, and differentiation. However, current approaches are affected by either fabrication complexity, limitations in the extent of mechanical stimuli, lack of full spatio-temporal control, or ease of use.

Bridging of liquid drops at chemically structured walls.

Using mesoscopic interfacial models and microscopic density functional theory we study fluid adsorption at a dry wall decorated with three completely wet stripes of width L separated by distances D_{1} and D_{2}. The stripes interact with the fluid with long-range forces inducing a large finite-size contribution to the surface free energy. We show that this nonextensive free-energy contribution scales with lnL and drives different types of bridging transition corresponding to the merging of liquid drops adsorbed at neighboring wetting stripes when the separation between them is molecularly small.

Geometry-induced interface pinning at completely wet walls.

We study complete wetting of solid walls that are patterned by parallel nanogrooves of depth D and width L with a periodicity of 2L. The wall is formed of a material which interacts with the fluid via a long-range potential and exhibits first-order wetting transition at temperature T_{w}, should the wall be planar. Using a nonlocal density functional theory we show that at a fixed temperature T>T_{w} the process of complete wetting depends sensitively on two microscopic length scales L_{c}^{+} and L_{c}^{-}.

N-glycosylation of tomato nuclease TBN1 produced in N. benthamiana and its effect on the enzyme activity.

A unique analysis of an enzyme activity versus structure modification of the tomato nuclease R-TBN1 is presented. R-TBN1, the non-specific nuclease belonging to the S1-P1 nuclease family, was recombinantly produced in N. benthamiana.

Sphingolipidomics of Thermotolerant Yeasts.

Mass spectrometry-based shotgun lipidomics was applied to the analysis of sphingolipids of 11 yeast strains belonging to four genera, that is Cryptococcus, Saccharomyces, Schizosaccharomyces, and Wickerhamomyces. The analysis yielded comprehensive results on both qualitative and quantitative representation of complex sphingolipids of three classes-phosphoinositol ceramide (PtdInsCer), mannosyl inositol phosphoceramide (MInsPCer), and mannosyl diinositol phosphoceramide (M(InsP) Cer). In total, nearly 150 molecular species of complex sphingolipids were identified.

Continuous condensation in nanogrooves.

We consider condensation in a capillary groove of width L and depth D, formed by walls that are completely wet (contact angle θ=0), which is in a contact with a gas reservoir of the chemical potential μ. On a mesoscopic level, the condensation process can be described in terms of the midpoint height ℓ of a meniscus formed at the liquid-gas interface. For macroscopically deep grooves (D→∞), and in the presence of long-range (dispersion) forces, the condensation corresponds to a second-order phase transition, such that ℓ∼(μ_{cc}-μ)^{-1/4} as μ→μ_{cc}^{-} where μ_{cc} is the chemical potential pertinent to capillary condensation in a slit pore of width L.