Interactions in Active Colloids

The past two decades have seen a remarkable progress in the development of synthetic colloidal agents which are capable of creating directed motion in an unbiased environment at the microscale. These self-propelling particles are often praised for their enormous potential to self-organize into dynamic nonequilibrium structures such as living clusters, synchronized superrotor structures or self-propelling molecules featuring a complexity which is rarely found outside of the living world. However, the precise mechanisms underlying the formation and dynamics of many of these structures are still barely understood, which is likely to hinge on the gaps in our understanding of how active colloids interact. In particular, besides showing comparatively short-ranged interactions which are well known from passive colloids (Van der Waals, electrostatic etc.), active colloids show novel hydrodynamic interactions as well as phoretic and substrate-mediated “osmotic” cross-interactions which hinge on the action of the phoretic field gradients which are induced by the colloids on other colloids in the system. The present article discusses the complexity and the intriguing properties of these interactions which in general are long-ranged, non-instantaneous, nonpairwise and non-reciprocal and which may serve as key ingredients for the design of future nonequilibrium colloidal materials. Besides providing a brief overview on the state of the art of our understanding of these interactions a key aim of this review is to emphasize open key questions and corresponding open challenges.

TREATMENT OF TEXTILE EFFLUENT USING NATURALLY PREPARED COAGULANT FROM MORINGA OLEIFERA SEED

This investigation is intended for Chemical Oxygen Demand (COD), Total Dissolved Solid (TDS), Biological Oxygen Demand (BOD), Conductivity, Dissolved oxygen, Absorbance, PH and turbidity reduction from textile industrial produce effluents that are highly complex and characterized. In this study coagulant using Moringa Oliefera seed was used to reduce the suspended and colloidal materials responsible for turbidity of the waste water. The seed powder was used as a natural coagulant to reduce turbidity, the test were carried out using textile effluent with conventional test apparatus. Various result were obtained by increasing dosage of Moringa Oleifera seed powder from 4g to 24g optimum dosage for reduction of COD, BOD, TDS, Turbidity, Conductivity, Absorbance and D.O was determined. It was observed that the highest dose which is 24g has a greater efficiency in reduction of all parameters tested with Ph of 6.48, COD 46mg/L, BOD 12mg/L, and Conductivity 360MSCm-1, TDS 212mg/L, Turbidity 8NTU, DO 4.7 and absorbance of 0.65. Moringa Oleifera seed showed potential in industrial textile effluent treatments among others.

Selective switching of multiple plexcitons in colloidal materials: directing the energy flow at the nanoscale

Two sets of plexcitonic resonances are selectively activated and connected by a relaxation cascade in colloidal particle-porphyrin nanosystems.

Nucleobase morpholino β amino acids as molecular chimeras for the preparation of photoluminescent materials from ribonucleosides

Bioinspired smart materials represent a tremendously growing research field and the obtainment of new building blocks is at the molecular basis of this technology progress. In this work, colloidal materials have been prepared in few steps starting from ribonucleosides. Nucleobase morpholino β-amino acids are the chimera key intermediates allowing Phe–Phe dipeptides’ functionalization with adenine and thymine. The obtained compounds self-aggregate showing enhanced photoluminescent features, such as deep blue fluorescence and phosphorescence emissions.

Nanofibrillar networks enable universal assembly of superstructured particle constructs

Superstructured colloidal materials exploit the synergies between components to develop new or enhanced functions. Cohesion is a primary requirement for scaling up these assemblies into bulk materials, and it has only been fulfilled in case-specific bases. Here, we demonstrate that the topology of nanonetworks formed from cellulose nanofibrils (CNFs) enables robust superstructuring with virtually any particle. An intermixed network of fibrils with particles increases the toughness of the assemblies by up to three orders of magnitude compared, for instance, to sintering. Supramolecular cohesion is transferred from the fibrils to the constructs following a power law, with a constant decay factor for particle sizes from 230 nm to 40 μm. Our findings are applicable to other nanofiber dimensions via a rationalization of the morphological aspects of both particles and nanofibers. CNF-based cohesion will move developments of functional colloids from laboratory-scale toward their implementation in large-scale nanomanufacturing of bulk materials.