Search results for "PHIP"

No room for males in caves : Female‐biased sex ratio in subterranean amphipods of the genus Niphargus

2021

Sex allocation theory predicts that the proportion of daughters to sons will evolve in response to ecological conditions that determine the costs and benefits of producing each sex. All else being equal, the adult sex ratio (ASR) should also vary with ecological conditions. Many studies of subterranean species reported female-biased ASR, but no systematic study has yet been conducted. We test the hypothesis that the ASR becomes more female-biased with increased isolation from the surface. We compiled a dataset of ASRs of 35 species in the subterranean amphipod Niphargus, each living in one of three distinct habitats (surface-subterranean boundary, cave streams, phreatic lakes) representing …

Odd-even chain length-dependent order in pH-switchable self-assembled layers.

2004

The reversible self-assembly of a series of bipolar amphiphiles, alpha,omega-bis(3- or 4-amidinophenoxy)alkanes (chain length n = 5-12), on mercaptoalkanoic acid-functionalized gold surfaces (chain length n = 10, 11, 14, 15) has been studied by in-situ ellipsometry, IR reflection absorption spectroscopy (IRAS), and atomic force microscopy (AFM). The layer order, amphiphile orientation, and tendency to form bilayers depends on the position of the amidine substituent, the alkyl chain length of both the amidine amphiphile and the underlying acid self-assembled monolayer (SAM), and whether the amidine alkyl chain contained an even or odd number of methylene groups. Thus, para-substituted bisben…

Structure and Shear Response of Janus Colloid–Polymer Mixtures in Solution

2020

We investigate the structure and rheological properties of dilute colloid-polymer mixtures at rest and under shear via molecular simulations that take into account hydrodynamic interactions. Mixtures of amphiphilic Janus colloids (JCs) and hydrophobic/amphiphilic polymers are considered for various solvent qualities and polymer concentrations. Free polymers, small polymer droplets, and hybrid aggregates coexist in mixtures with slightly hydrophobic homopolymers. As the solvent quality worsens, all polymers aggregate into small droplets, covered and stabilized by the JCs. In mixtures with amphiphilic polymers, we observe the coexistence of free polymers, purely polymeric micelles, and hybrid…

Fragment condensation on solid-phase in the synthesis of an amphiphilic glycopeptide from the homophilic recognition domain of epithelial cadherin 1

1998

Abstract The lipo-glycopeptide 6 containing the homophilic recognition motif of mouse epithelial cadherin 1 was synthesised via a fragment condensation on a solid phase linked peptide using an allylic anchor and a pentafluorophenol-based coupling reagent.

Amphiphilic Polyethers of Controlled Chain Architecture

2003

The amphiphilic polymers, polymers which contain in their macromolecules both hydrophilic and hydrophobic units1, are the base for valuable materials due to their diversified interaction with liquids. So they may act as emulsifiers, compatibilizers, “smart” materials (responding to external stimuli)2 and many others. In order to control their properties, the hydrophilic — hydrophobic balance in the macromolecules has to be controlled. This balance depends not only upon the constitution of the chain repeating units, but also upon the art of their distribution in the chains (copolymers of controlled unit sequences), the chain topology, the size of the chains and many others. So a careful engi…

2020

The pH-responsive nature of two self-assembled NDI-peptide amphiphile conjugates is reported. The diethoxy substituted NDI showed a pH-dependent assembly behaviour, as expected. In contrast, the isopropylamino- and ethoxy-substituted NDI based supramolecular polymer was stable at acidic and basic aqueous conditions. This finding highlights how subtle changes in the molecular design of π-stacked chromophore-peptide conjugates have a drastic impact on their equilibrium structure and ultimately functional properties.

Molecular Recognition-Induced Function and Competitive Replacement by Hydrogen-Bonding Interactions:  Amphiphilic Barbituric Acid Derivatives, 2,4,6-…

1998

The phenomenon of molecular recognition inducing further function is common in nature. However, there are few synthetic systems which achieve this cascade type mechanism, and those are generally ca...

Conformational polymorphism and amphiphilic properties of resorcinarene octapodands

2010

o-Nitroaniline functionalized resorcinarene octapodands 1-5 with pendant methyl, ethyl, pentyl, nonyl or 1-decenyl groups, respectively, were synthesized and their structural properties investigated using X-ray crystallography and NMR spectroscopy. The upper rim of each podand is identical containing flexible side arms, in which rotation around the -OCH(2)CH(2)N- linkers create excellent possibilities for polymorphism. Two conformational polymorphs of acetone solvate of 2 were identified containing different side arm orientation and crystal packing. Compound 1 crystallized from acetone and nitromethane yielding two pseudopolymorphs with different packing motifs. The longer alkyl chains of 3…

Cover Feature: Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells (ChemBioChem 9/2018)

2018

A minimal hydrophobicity is needed to employ amphiphilic p(HPMA)-co-p(LMA) random copolymers in membrane research.

2014

Because a polymer environment might be milder than a detergent micelle, amphiphilic polymers have attracted attention as alternatives to detergents in membrane biochemistry. The polymer poly[N-(2-hydroxypropyl)-methacrylamid] [p(HPMA)] has recently been modified with hydrophobic lauryl methacrylate (LMA) moieties, resulting in the synthesis of amphiphilic p(HPMA)-co-p(LMA) polymers. p(HPMA)-co-p(LMA) polymers with a LMA content of 5 or 15% have unstable hydrophobic cores. This, on one hand, promotes interactions of the hydrophobic LMA moieties with membranes, resulting in membrane rupture, but at the same time prevents formation of a hydrophobic, membrane mimetic environment that is suffici…