Interstitial diffusion

Diffusion in the bulk of a crystal can occur by two mechanisms. The first is interstitial diffusion. Atoms in all crystals have spaces, or interstices, between them, and small atoms dissolved in the crystal can diffuse around by squeezing between atoms, jumping - when they have enough energy - from one interstice to another (Fig. 18.6). Carbon, a small atom, diffuses through steel in this way in fact C, O, N, B and H diffuse interstitially in most crystals. These small atoms diffuse very quickly. This is reflected in their exceptionally small values of Q/RTm, seen in the last column of Table 18.1. 

This patient has the subjective symptoms of weight loss, decreased appetite, shortness of breath, and cough. Abnormal laboratory values include elevated temperature, decreased hemoglobin and hematocrit, and decreased CD4 count. Chest x-ray shows diffuse interstitial infiltrates bilaterally. Physical exam reveals thrush. The assessment is possible AIDS with CD4 count of 150 cells/mm3, thrush, a respiratory illness (possibly Pneumocystis jiroveci pneumonia), and anemia of chronic disease. He also has a history of hepatitis B, hypertension, and GERD (on famotidine), poor adherence to his anti hypertensive medications, and likely has an irregular daily regimen due to his occupation as a truck driver. 

Histopathological evidence of renal damage has been observed in lead-exposed workers. Renal ultrastructure and function were examined in five men with heavy occupational exposure to lead (Cramer et al. 1974). In addition, renal function was evaluated in two men from whom renal biopsies were not obtained. PbB levels ranged from 71 to 138 pg/dL. Renal function tests were normal in all except for a reduced glomerular filtration rate in one worker. Two subjects with relatively short exposure to lead (6 weeks and 8 months) and PbB levels of 89-129 pg/dL had intranuclear inclusions in the proximal tubules. Renal biopsies from workers with longer periods of lead exposure (4-20 years, PbB levels of 71-138 pg/dL) had diffuse interstitial or peritubular fibrosis. Glomeruli were normal in all subjects. 

Radiographic findings are nonspecific and include bronchial wall thickening and perihilar and diffuse interstitial infiltrates. 

In the case of interstitial diffusion in which we have only a few diffusing interstitial atoms and many available empty interstitial sites, random-walk equations would be accurate, and a correlation factor of 1.0 would be expected. This will be so whether the interstitial is a native atom or a tracer atom. When tracer diffusion by a colinear intersticialcy mechanism is considered, this will not be true and the situation is analogous to that of vacancy diffusion. Consider a tracer atom in an interstitial position (Fig. 5.18a). An initial jump can be in any random direction in the structure. Suppose that the jump shown in Figure 5.18b occurs, leading to the situation in Figure 5.18c. The most likely next jump of the tracer, which must be back to an interstitial site, will be a return jump (Fig. 5.18c/). Once again the diffusion of the interstitial is different from that of a completely random walk, and once again a correlation factor, / is needed to compare the two situations. 

Coates EO Jr, Watson JHL Diffuse interstitial lung disease in tungsten-carbide workers. Ann Intern Med 75(5) 709-716, 1971... 

Dexamethasone Testing of adrenal cortical hyperfunction cerebral edema associated with primary or metastatic brain tumor, craniotomy, or head injury. Tnamc/no/one Treatment of pulmonary emphysema where bronchospasm or bronchial edema plays a significant role, and diffuse interstitial pulmonary fibrosis (Hamman-Rich syndrome) in conjunction with diuretic agents to induce a diuresis in refractory CHF and in cirrhosis of the liver with refractory ascites and for postoperative dental inflammatory reactions. 

L ii can be evaluated by introducing the interstitial mobility M, which is the average drift velocity, tq, gained by diffusing interstitials when a unit driving force is applied, that is,... 

Consider an ionic material that contains a dilute concentration of positively charged ions that diffuse interstitially (interstitial diffusion is described in Section 8.1.4). D is the interdiffusivity of these ions in the absence of any field. As shown in Sections 2.2.2 and 2.2.3, if an electric field, E = —V, is applied, the diffusion potential will be the electrochemical potential given by Eq. 2.41. According to Eq. 2.21, the flux of charged interstitials is... 

Scanning electron microscopy (SEM) in concert with x-ray energy spectrometry (XES) has been used to detect silver in pulmonary, lacrimal sac, and skin tissues of individuals with diffuse interstitial lung disease, chronic dacryocystitis, and skin disorders, respectively (Brody et al. 1978 Loeffler and Lee 1987 Tanita et al. 1985). Brody et al. (1978) observed particles of preselected lesions of human pulmonary tissue magnified to 300x by SEM, and the silver content was analyzed by XES. The authors noted that SEM and XES techniques permit a rapid and conclusive determination of silver, silver compounds, and complexes in tissue lesions. 

Rat 15 Inhalation 660 90 d, continuous 13 of 15 animals died. Histopathologic examination revealed focal or diffuse interstitial pneumonitis, calcification of renal tubules, calcification of bronchial epithelial, renal tubular epithelial proliferation, myocardial fibrosis fatty changes of the liver in several animals. Changes were also found in control animals, but were of lesser seventy. LOAEL 660 Goon et al. 1970... 

Decreased phagocytosis leading to interaction of the particles with the epithelium, resulting in the development of conditions such as chronic diffuse interstitial fibronodular lung disease... 

Katjalainen A, Anttila S, Heikkila L. 1993b. Ix)be of origin of lung cancer among asbestos-exposed patients with or without diffuse interstitial fibrosis. Scand J Work Environ Health 19(4) 102-107. 

A chest X-ray showed diffuse interstitial and alveolar infiltrates and small bilateral pleural effusions. A high-resolution CT scan of the chest showed diffuse ground-glass attenuation and patchy peripheral opacities, consistent with an acute hypersensitivity pneumonitis, and other diagnoses were ruled out. He responded to gluco-corticoids. 

Ocular hypertelorism. Pulmonic stenosis, Abnormahties of the genitalia. Retarded growth, and sensorineural Deafness (36). A CT scan showed diffuse interstitial injury characterized by thickening of the intralobular septa, with areas of ground-glass pattern. Flecainide was withdrawn and within 2 weeks the changes on CT scan had almost completely disappeared. 

Findings on autopsy and endomyocardial biopsy have shown diffuse, interstitial edema, intracytoplasmic vacuolization of myocytes, and no inflammatory infiltrate (34). Acute myocardial infarction has been demonstrated pathologically in some, but not all, patients with clinical infarction (10). 

A 54-year-old woman with psoriatic polyarthritis was treated with aurothiomalate 50 mg/week. When the cumulative dose reached 250 mg she developed weakness, dyspnea, fever, nausea, vomiting and erythematous skin lesions. Chest X-ray and CT scan showed diffuse interstitial pneumonitis. Gold was withdrawn and she was given prednisone 60 mg/day. She recovered in 6 months. 

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