Adhesion number

Colloidal gold staining Measures the adhesion number ... 

Colloidal gold staining has been introduced by Park [24] for studying the adhesion number. The polymer in a form of strips is incubated with colloidal gold-... 

Other in vitro methods include the determination of the weight needed to break the adhesion [41], the fluorescent probe [35], the flow channel [42], mechanical spectroscopy [43], the falling film [44], colloidal gold staining [45], viscometiy [46], the thumb test [47], the adhesion number [47], and electrical conductance [47]. 

To measure the adhesion strength of bacteria, it is necessary to remove them from the surface. Weiss (1961) measured bacterial adhesion by allowing cells to settle onto a glass surface of a sealed chamber, and then counting them with the aid of a microscope. After a period of incubation the chamber was turned upside down, the unattached cells fell from the surface and the remaining attached cells were recounted. This adhesion number method is purely observational, as it does not measure adhesion directly. Weiss also described a disc-shearing device,... 

Absence of breakdown under test voltage (kV) Transient electrical resistance (S2 m ) Impact strength (kgfcm) Adhesion, number... 

Adhesion Number for Monodisperse Particles. Let us first consider methods used in evaluating the adhesion of a monolayer of particles. Adhesion is characterized by the force produced when particles come into contact with various sur-... 

Subsequently, the concept of adhesion number was extended [14,15] and it is now understood to be the ratio between the number of particles N remaining after the application of a certain detachment force and the number of particles Aq originally present on the test surface. The adhesion number is often expressed as a percentage ... 

Sometimes, particularly in the detachment of particles by an air or water stream (Chapters X and XI), we do not use the adhesion number, but rather the reciprocal of the adhesion number. This quantity is termed the coefficient of removal ... 

The adhesion number jp is expressed as a percentage in this particular instance. The coefficient of removal indicates the factor by which the number of adherent particles is reduced after the application of an external force to detach these particles. 

Let us note in passing that Buzagh determined the slope (see Section 11) of a dust-covered plate and thereby determined the adhesion number, not the distribution of particles with respect to adhesive forces. 

Adhesion Number for Polydisperse Particles. The adhesion number in the detachment of polydisperse particles that are subjected to a specific force can be represented as the arithmetic average of the adhesion numbers characteristic for monodisperse fractions of these particles ... 

If the symbols A o and N are used to denote the numbers of polydisperse particles before and after application of a specific detachment force, the adhesion number for such particles will be... 

The variation of adhesion number with particle size when these particles are detached, for example, by vibration or by a water stream [16], is given by... 

In Eq. (1.9), the adhesion number Ypid) allows us to weight the final distribution of particles with respect to the initial i.e., Tf( ) is the number of particles of various sizes that are removed under the influence of external forces. In order to calculate the adhesion number, in addition to 7f( ) we need to know the size distribution of the adherent poly disperse particles. This distribution most frequently follows a log-normal law [16]... 

When the transformations (1.9)-(1.14) are taken into account, the adhesion number for polydisperse particles is determined from the formula... 

Calculations show that the ratio 2 [ ]/ i [ ] has values of 0.95-0.99. Hence, without any great detriment to the accuracy of the calculation, we can determine the adhesion number from the simplified formula... 

In order to calculate the adhesion number of polydisperse particles, we need to know the parameters a and d characterizing the particle size distribution, values of B as defined in Eq. (1.16), and the adhesive properties of the particles, which are taken into account by the parameters a and b. 

As can be seen from these data, the calculated and experimental values of adhesion number show satisfactory agreement in the removal of polydisperse particles, thus demonstrating the correctness of the proposed calculation methods. 

Evaluation of Adhesive Interaction by Means of Force. The dependence of adhesion number on the forces holding the particles of a monodisperse dust on a surface is commonly characterized by integral curves of adhesive force [14] (Fig. 1.2). The force of adhesion can be expressed in integral curves either in absolute quantities or in -units.f The force of adhesion ing -units, i.e., the ratio of adhesive force to the particle weight, has been termed the coefficient of adherence by G. I. Fuks [12]. 

Adhesion can be compared under different conditions either on the basis of the force required for detachment (or retention), of a given number of particles, or of the adhesion number (i.e., the number of remaining particles) for a given detachment force [18]. 

Fi is considerably smaller than the force F4 i.e., in the first case (curve 1), the majority of the particles are torn off more readily than in the fourth case (curve 4). Here, evidently, adhesion is better evaluated on the basis of the detachment force for an adhesion number of 50% (see Fig. 1.2.a). We must also note that certain cases are likewise possible, although less probable, in which the detachment force F50 will be equal for a family of curves (Fig. I.2.b) but will not reflect the features of adhesive interaction. 

Thus we see that the evaluation of adhesion on the basis of the detachment force at identical adhesion numbers (i.e., on the basis of F, in, F ax or so) can lead to errors. In exactly the same manner, the evaluation of adhesion on the basis of adhesion numbers at equal detachment forces can serve only as a relative characterization of the interaction forces between particles and surface. 

Average Acceleration in Particle Detachment. The magnitude of adhesion would be better evaluated by means of a single index that would account for the distribution of adherent particles with respect to adhesive forces, i.e., the adhesion numbers and the equivalent adhesive forces. The evaluation of adhesion on the basis of the average adhesive force [18] is such a method. 

The efficiency of particle removal can be expressed by means of the removal coefficient or the adhesion number yp [23]... 

From this discussion, it can be seen that the efficiency of removal of adherent particles from different surfaces may be characterized not only by the adhesion number, but also by the coefficient of removal, which is a function of the probability of detachment and removal of the adherent particles. If we know the relationship between the average force of adhesion and the particle size, i.e., Fav - fid), and if the detachment force F et =/( ) is fixed, the method we have just examined can be used to determine the probability of particle detachment over a range of sizes from to c/max ... 

The magnitude of 0 can be determined (for now) indirectly on the basis of adhesion number. 

The relationship between adhesion numbers determined by tangential and normal detaching forces is expressed by empirical formulas obtained through treatment of experimental data [14] ... 

---