מכל מלמדײ השכלתי (duchifat) wrote,
מכל מלמדײ השכלתי
duchifat

Кто открыл гистерезис контактного угла?

Из гранок нашей статьи в Colloid Polym Sci. Рецензент требовал сократить лит. обзор и убрать исторические отступления. Я не сократил и не убрал. :) Мне очень понравилось, что без дураков поиск литературы вывел на такую изумительную историю -- одноногая чернокожая лесбиянкаTM женщина-самородок без образования, ставшая ученым, стоит у истоков этого дела. Израильские друзья мне говорили, что гистерезис КА одним из первых открыл в 1930-е наш политеховец проф Я. И. Френкель (затравленный во время борьбы с космополитизмом и физическим идеализмом Эйнштейна-Бора). Но все же это было попозже, Якова Ильича мы тоже уважаем и любим.

Since the concept of the CA was introduced, it was
realized that this single parameter cannot completely char-
acterize wetting. Furthermore, there is no one single value of
the CA, but it can have a range of values θrec≤θ≤θadv, where
θrec and θadv denote the receding and advancing contact
angles, respectively. The contact angle can be measured also
on a tilted surface (Fig. 2), although it is recognized that the
values measured in this way do not always provide true
values of the advancing and receding angles [3]. The differ-
ence between the advancing and receding CA is called CA
hysteresis. Originally, CA hysteresis was associated with
surface contaminants. Lord Rayleigh [4] noted that for con-
taminated glass surfaces, the CA can vary significantly,
since “if after the drop is deposited, some of the liquid is
drown off, the angle may be diminished almost to zero.”

This phenomenon was described in a letter from a German
scientist Agness Pockels, who had no formal education and
made observation on dishes in a kitchen sink. She observed
that water droplets behaved differently on clean and con-
taminated glass surfaces. She wrote a letter to Rayleigh who
published it in the journal Nature [5]:
The surface tension of a strongly contaminated water
surface is variable; that is, it varies with the size of the
surface. The minimum of the separating weight attained by
diminishing the surface is to the maximum, according to my
balance, in the ratio of 52: 100. If the surface is further
extended, after the maximum tension is attained, the sepa-
rating weight remains constant, as with oil, spirits of wine,
and other normal liquids. It begins, however, to diminish
again, directly the partition is pushed back to the point of the
scale at which the increase of tension ceased. The water
surface can thus exist in two sharply contrasted conditions;
the normal condition, in which the displacement of the
partition makes no impression on the tension, and the anom-
alous condition, in which every increase or decrease alters
the tension
” [4].
This phenomenon was later investigated by Pockels [5],
Ablett [6], and Adam and Jessop [7] who wrote: “In the
extreme cases, the angle when the liquid is advancing over
the solid may be 60o greater than when it is receding. It is
not necessary that there should be actual motion, for a force
on the liquid tending to move it has the same effect. The
phenomenon is obvious on inspection of a drop of water on
slightly dirty glass plate; it appears to have been first de-
scribed in detail by Pockels… The cause of this dragging
effect (often called “hysteresis” of the angle of contact)

seems to us to lie, not in any absorption of the liquid by
the solid, but in a simple friction of the liquid on the
surface” [7].
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  • dybr

    В Питере нарастает волна эпидемии, я очень боюсь, что, танцы закроют. Тут провакцинировано только 10% населения (а для стадного иммунитета надо 50%),…

  • (no subject)

    Много говорят о версии утечки вируса из Уханского институте вирусологии. При этом никаких новых данных в пользу этой версии нет. Эта версия…

  • (no subject)

    Бачата в Парке Победы вчера

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