Skin hardening

In chronic arsenic poisoning anorexia, anaemia, disturbances in renal and hepatic function, dermatitis, skin hardening (hyperkeratosis) and pigmentation can occur. Arsine gas is a powerful haemolytic agent and symptoms of poisoning are due to its action on the blood. 

Calabashes are gourdes. The ripe Suit are heavy and soft, but get lighter as they dry and their skins harden. They turn brown when they are dried. 

Fig. 24.2 Skin hardening of a the Si(OOl), Si(l 11), and Si02 skins [19], b the silica-based low-dielectric films [20], and c the modulus-depth profile of a CNT turf showing one order higher in magnitude at the skins. Indentations are taken at different distances from the edge of the turf. The more compliant cases correspond to indentations closer to the edge [31]. Skin softening of d polymer [33], measured using AFM indentation. Outlined and filled symbols correspond to the values estimated using the pyramidal diamond and spherical indenters, respectively, for thick (squares) and thin (triangles) polymer films (reprinted with permission from [111])...

The measured skin hardening or softening also varies with methods of detection. For instance, the modulus of nanocrystalline of 50-800-nm-thick Ni films, measured using acoustic AFM [35], is lower than that of the bulk, as no artifacts such as accumulation of dislocations are involved in the non-contact acoustic AFM method. SiTiN films are measured approximately 10-20 % harder using nanoindentation than the values obtained using SAWs methods [36]. The additional pressure due to compression will cause deviation of the intrinsic values. Therefore,... 

This is similar to the variation in the skin hardening and softening as discussed in Sect. 24.3. For instance, the Y value of ZnO nanobelts of 50-140 nm thick and... 

Potassium alum, which also occurs naturally as the mineral kalinite [7784-24-9], KAl(SO 2 12H20, sp gr 1.75, is used ia tanning skins, as a mordant ia dyeiag, and ia the pharmaceutical and cosmetic iadustries (see Pharmaceuticals Cosmetics). It is used as a styptic pencil and as a hardening agent and set accelerator for cement and plaster. The ACGIH threshold limit value TWA is 2 mgAl/m (1 ). 

Diethylcarbama2iae has limited antimicrofilarial activity against Onchocerca volvulus. Adults of W. bancrofti the filarial worm causiag elephantiasis, coil in the lymph system. Here females can attain a length of 10 cm. Over the years, tissue reactions result in obstmction to lymph return. Lymph nodes, lymph vessels, and the spleen become enlarged. The condition of elephantiasis is a late and unusual complication of filariasis, where the lower extremities of the body become edematous, enlarge, and over a period of time harden with a rough nodular skin. 

Nail hardeners have been based on various proteia cross-linking agents. Only formaldehyde is widely used commercially. Contact with skin and inhalation must be avoided to preclude sensiti2ation and other adverse reactions. The popularity of products of this type is decreasiag because the polymers used ia nail elongators can be used to coat nails to iacrease the mechanical strength. 

Series major additive Cu Al -r 4 Cu -r Mg, Si, Mn Strong age-hardening alloy aircraft skins, spars, forgings, rivets. 

It is thus seen that as a class the primarily aliphatic amines provide fast-curing hardeners for use at room temperatures. With certain exceptions they are skin sensitisers. The chemical resistance of the hardened resins varies according to the hardener used but in the case of the unmodified amines is quite good. The hardened resins have quite low heat distortion temperatures and except with diethylenetriamine seldom exceed 100°C. The number of variations in the properties obtainable may be increased by using blends of hardeners. 

Meta-phenylenediamine, a crystalline solid with a melting point of about 60°C, gives cured resins with a heat distortion temperature of 150°C and very good chemical resistance. It has a pot life of six hours for a 200 g batch at room temperature whilst complete cures require cure times of four to six hours at 150°C. About 14 pts phr are used with the liquid epoxies. The main disadvantages are the need to heat the components in order to mix them, the irritating nature of the amine and persistent yellow staining that can occur on skin and clothing. The hardener finds use in the manufacture of chemical-resistant laminates. 

Hardener Parrs used per 100 pts resin Pot life (500 g batch) Typical cure schedule Skin irritant Max HOT cured resin rcj Features Applications... 

The monomers, eatalysts or hardeners, or plastieizers ean inelude ehemieals with the potential to irritate the skin, mueous membranes or respiratory traet. Some ean promote skin or respiratory sensitization. The range of ehemieals in use is extremely wide, so that referenee should be made to the Materials Safety Data Sheet for eaeh speeifie formulation or variation of it identifiable by referenee to the supplier s proprietary name and eode number. Some eommon resin types are summarized in Table 5.55. 

Sodium a-sulfomethylmyristate is used together with the sodium salt of hardened beef tallow fatty acid to produce a soap with little skin irritation [88]. Shampoos for application to hair as well as skin comprise a-sulfo fatty acid ester salts, fatty acid dialkanolamides, and citric acid. For example, a shampoo that consists of 15% sodium a-sulfoethylmyristate, 3% lauric acid diethanolamide, 0.5% citric acid, and 81.5% water is very effective even in hard water and only slightly irritating to the skin [89]. 

Humphrey and Seal9 (U.S.A.) reported in 1959 detailed experiments on the ECT of sarcoma-180 tumors in nearly 500 mice. In a typical experiment, 18 test animals and 18 control animals were used the ECT was done with 3 ma current, at 6 V for 3 hours a day, for 24 days. They observed that after such a lengthy treatment, the mean volume of test tumors was about 15% of the mean tumor volume of the control group seven mice showed complete tumor regression as a result of ECT. Total regression means that the tumor has decreased progressively in volume, hardened, dropped off, leaving a new skin surface at the former tumor site. 

Onions for storage Once harvested, bulb onions need to be kept in a warm, dry, airy environment for a week or two to "harden" their skins so that they will store well. In sunny weather you can leave them on the soil surface (see also p.271). 

In contact with the eyes, the liquid produces severe burns, which may result in permanent damage and visual impairment. On the skin, the liquid or concentrated vapor produces immediate, severe, and penetrating burns concentrated solutions cause deep ulcers and stain the skin a bright yellow or yellowish-brown color.Dilute solutions of nitric acid produce mild irritation of the skin and tend to harden the epithelium without destroying it. 

---