The effect of friction reduction in presence of ultrasonic vibrations and its relevance to travelling wave ultrasonic motors.

In many ultrasonic applications frictional effects play an important role (e.g. ultrasonic machining, ultrasonic motors). For optimising the applications in terms of quality, efficiency and lifetime it is important to understand the frictional coupling of the vibrating and the non-vibrating part. This contribution is devoted to give an explanation for the reduction of friction forces which is often observed when ultrasonic vibrations are superimposed to macroscopic motions. Usually adopted coefficients of friction are used for modelling such conditions suggesting special frictional mechanisms for high frequency oscillations, whereas the present paper shows that Coulomb's friction law provides a very good description of the observed phenomena if the kinematics of the system is taken into account. Two systems are investigated. In the first system the ultrasonic and macroscopic movements are parallel and in the second they are perpendicular to each other but also within the plane of contact. Both systems were investigated analytically and experimentally using a specially designed test rig. The measurements confirmed the analytically derived equations and therefore the validity of Coulomb's friction law even for ultrasonic conditions.

[Is malignant melanoma really radiation resistant?]. / Ist das maligne Melanom wirklich strahlenresistent?

The efficiency of radiotherapy of malignant melanoma is discussed according to observations by other clinicians and ourselves. There is no proof that the melanoma is radiotherapy-resistant. The clinical radiosensitivity of human melanoma can be compared with the experimental hamster or mice melanoma or with the sensitivity of cultured melanoma cells. The possibility of increasing the efficiency of radiotherapy in the future by electroaffine sensitizers, fast electrons, or neutrons with a high LET and a small OER is mentioned.

Skin test and lymphocyte stimulation in delayed hypersensitivity against staphylococcal antigens. Relation to bacterial cell fractions.

Staphylococcal homogenate was fractionated into cell walls (CW), cell membranes (CM) (insoluble part left after removal of the cell wall fraction) and a soluble fraction. The capacity of these fractions to evoke delayed skin reactions and to stimulate lymph node and peripheral blood lymphocytes from guinea pigs sensitized with staphylococcal homogenate in Freund's complete adjuvant was tested 21 days after sensitization. Highest skin reactivity was observed with the cell wall fraction. In the lymphocyte stimulation test similar results were obtained with all three fractions. With peripheral blood lymphocytes higher stimulation indices were observed than with lymph node lymphocytes.

Skin test and lymphocyte stimulation in delayed hypersensitivity against Staphylococcus aureus antigens. Development of hypersensitivity.

The development of delayed hypersensitivity against staphylococcal antigens in guinea pigs was observed from day 3 to day 50 after sensitization with staphylococcal homogenate in Freund's incomplete (FIA) and Freund's complete adjuvant (FCA). Skin test reactivity, stimulation of lymph node lymphocytes, and peripheral blood lymphocytes and the titre of precipitating antibodies were followed during this period. Maximal skin test reactivity as well as maximal lymphocyte responsiveness occurred at day 21 after sensitization in FCA-sensitized guinea pigs. In FIA-sensitized animals highest skin reactivity was observed at day 14 and maximal lymphocyte stimulation 35 days after sensitization. Precipitating antibodies reached a plateau at day 20 in plasma of animals sensitized with FCA and at day 35 in FIA-sensitized animals.

[The explained and the unexplained in dermatological immunology]. / Geklärtes und Ungeklärtes der dermatologischen Immunologie.

By means of classical allergologic and modern immunologic test methods, as well as recent knowledge about antigens and antibody reactions, some dermatoses can be classified with good probability into the allergy types of Coombs and Gell. In other dermatoses much remains unclear. The problems are discussed with regard to several dermatoses and attempts are made to explain some skin alterations by the mentioned immunologic types of reaction.

[Triggering of immunologic reactions by Strehler's pressure wave therapy in patients with chronic venous insufficiency]. / Zur Frage der Auslösung immunologischer Reaktionen durch Druckwellentherapie nach Strehler bei Patienten mit chronisch venöser Insuffizienz.

Thirteen patients with chronic venous insufficiency of the legs, mostly with ulcerations, were treated during four weeks by pressure wave therapy following the method of Strehler. Some parameters of circulation, blood, and immunology were controlled at the beginning, at the third, tenth, twentieth and fourtieth day. There was a tendency to normalization of hypo- and hypertension, of the blood calcium and kalium, and especially, there was a significant increase of IgG and C'4 during the treatment with decrease of the IgM. Other parameters did not show specific alterations. The mobilisation of edema by pressure wave therapy seems to arise an immunologic reaction, probably by activating antigens or antigen-antibody complexes.

Radiotherapy of cutaneous cancers and some other malignancies.

The principles of radiotherapy for the common cutaneous carcinomas of the skin are discussed and results illustrated. Shorter accounts of X-ray therapy of other, less common malignancies are also presented.

Treatment of melanotic freckles by radiotherapy.

Uncomplicated cases of melanotic freckles respond well to radiotherapy with grenz rays. If, however, a conversion into melanoma is in progress or already established, the prognosis is poorer and treatment with harder rays combined with surgical excision should be practiced.