Automated identification of moth species

In this paper, Digital Automated Identification System (DAISY) was used to identify species of local moths. 210 species of super family Bombycoidea from Moth of Borneo (Part 3) were trained in DAISY. The overall identification of Moths gave a fairly accurate retrieval, with F1= 0.81

On particle bridging by small charged molecules

Particle bridging by small charged molecules was discovered quite recently. Only specific compounds with the appropriate structure and spatial position of the charged groups, display bridging behaviour. These compounds as a new class of functional additives are highly suitable for making strong gels and paste products. This type of bridging is highly directed towards maximising the strength of the flocculated network in dispersions. The small size of the molecules means that bridging can only take place at the closest point of interaction between particles (particle-particle bond) in the flocculated state, thus greatly strengthening the interparticle bond in the three-dimensional network. The yield stress is a measure of the\ud strength of the network. Particle bridging by small molecules can increase the maximum yield stress (at zero net charge condition) by as much as 10-fold. In this paper the elements of molecular structure of additives essential for bridging are discussed

Molecular configuration of adsorbed cis- and trans-1, 2-ethylene dicarboxylic acids and interparticle forces in colloidal dispersions

[Extract] There has not been a study linking the molecular configuration of adsorbed small charged molecules and the interparticle forces in flocculated dispersions. This study will illustrate the linkage with cis- and trans-1,2-ethylene dicarboxylic acids in a 24 vol%R-Al2O3 dispersion. The interparticle forces were evaluated from the yield stress1-8 of the dispersion. The cis-form acid weakens the flocculated network structure by forming a steric layer. The trans-form acid greatly reinforces this structure by bridging at the joints and network junctions. As a result, the dispersion developed a high yield stress and viscosity. This study may give rise to a new family of thickening agents based on small organic molecules that may be of use in products such as toothpaste, printing inks, cosmetics, paints, concrete mix, and paper-coating slurries

Principles of particle bridging by small molecules: structure and configuration

Particle bridging by small charged molecules was discovered quite recently. Only specific compounds with the appropriate structure and spatial position of the charged groups, display bridging behaviour. These compounds as a new class of functional additives are highly suitable for making strong gels and paste products. This type of bridging is highly directed towards maximising the strength of the flocculated network in dispersions. The small size of\ud the molecules means that bridging can only take place at the closest point of interaction between particles (particle-particle bond) in the flocculated state, thus greatly strengthening the interparticle bond in the three-dimensional network. The yield stress is a measure of the\ud strength of the network. Particle bridging by small molecules can increase the maximum yield stress (at zero net charge condition) by as much as IO-fold. In this paper the elements of molecular structure of additives essential for bridging are discussed

Chemicals from sugar cane as rheological modifying agents for dispersions

Sugar molasses contains thousands of chemical components and undoubtedly many of these components are potentially useful rheological modifying agents. In this study only a handful of these chemical components were evaluated for their rheological modifying properties with slurries. These compounds are cis- and trans-aconitic acids, citric acids, and a modified starch. A yield stress-pH technique was used to probe the surface forces arising from these adsorbed additives in colloidal alumina dispersions. Citric acid and starch decreased the maximum yield stress of the dispersion very significantly. These compounds adsorbed and acted as a steric layer. In contrast trans-aconitic acid increased the maximum yield stress quite substantially while its cis- counterpart did neither increase nor decrease the maximum yield stress. The trans-aconitic acid behaves as an effective particle-bridging agent. Its ciscounterpart\ud is neither effective as a bridging or steric agent. Trans-aconitic acid may be used as an additive for strengthening colloidal gels commonly found in foods and cosmetics. The\ud others may be used to reduce gel strength or yield stress of colloidal dispersion products

Critical zeta potential parameter for the characterization of the flocculated-dispersed state transition in colloidal dispersions

A colloidal dispersion in water is flocculated when the net interaction between particles is attractive. This occurs when the van der Waals force is stronger than the electrostatic repulsive force. The van der Waals force is constant at a given separation distance between particles and is strongest at the equilibrium separation distance in the flocculated state. The electrostatic force however may be varied from zero to a high value by surface potential control. pH is often used to manipulate the surface potential. The easily measurable zeta potential is normally used in place of the surface potential. This potential is measured at a shear plane near the particle surface and is proportional to the surface potential at constant ionic strength. There is a critical zeta potential where the electrostatic force is equal to the van der Waals force and the dispersion becomes dispersed. At fixed ionic strength the critical zeta potential is indirectly a measure of the strength of the van der Waals force in the flocculated state. Thus it is also a measure of the Hamaker constant, an important material property and parameter in the van der Waals equation. The critical zeta potential at fixed ionic strength of various oxide dispersions were compared. The yield stress and zeta potential data were used to determine the critical zeta potential at flocculated-dispersed state transition

Processing the Couette viscometry data of molasses by Tikhonov regularisation

This paper highlights a general and reliable technique for converting basic torque-rotational speed for molasses derived from Couette viscometers into true shear stress-shear rate data without a priori assumption of a fluid model. Obtaining the shear rate as a function of shear stress from Couette viscometry data is an inverse problem and is normally 'solved' by assuming a rheological model such as a power law model. An accurate method based on Tikhonov regularisation is developed to solve this inverse problem for the shear rate. The advantages of Tikhonov regularisation are highlighted. The performance of the new method is assessed by applying it to process the Couette data of molasses

Critical zeta potential and the Hamaker Constant of oxides in water

The critical zeta potential characterises the flocculated–dispersed state transition of a colloidal dispersion. For many colloidal dispersions, yield stress displayed a linear relationship with the square of zeta potential indicating that they obeyed the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. From this relationship, critical zeta potential is obtained from the intercept at the zeta potential axis at a yield stress of zero. The critical zeta potential is a measure of the repulsive potential required to exactly counter the maximum attractive potential between particles in dispersion in the flocculated state. When the forces of interaction between particles in the dispersion are only the van der Waals and electrostatic forces, then the critical zeta potential is indirectly a measure of the van der Waals attractive potential and, hence, it may be used to determine the Hamaker constant of solids in water. This potential is proportional to the square root of the solids Hamaker constant in water. At present, only the ratio of Hamaker constant between two oxides was obtained and compared with that obtained by other techniques. These oxides were ultrapure anatase TiO2 and γ-Al2O3, and they displayed a linear relationship between yield stress and the square of zeta potential. At the conductivity (or ionic strength) of about 3000 μS/cm, the critical zeta potential for both TiO2 and Al2O3 is ∼ 47 and ∼ 32 mV, respectively. These critical zeta potential data give a value of 2.2 for the ratio of Hamaker constant of anatase TiO2/H2O/TiO2 to γ-Al2O3/H2O/γ-Al2O3. This ratio compares well with a value ranging from 1.0 to 2.18 for rutile TiO2/H2O/TiO2 to α-Al2O3/H2O/α-Al2O3 where their Hamaker constants were calculated from the Lifshitz theory using full optical spectral data.\u