扩展电阻分析对砷在硅中本征扩散系数的研究

本文扼要叙述了扩展电阻分析用以测量较低浓度砷的剖面的有效性,进而研究了较低浓度砷在硅中的扩散问题.由于通过快速热退火对样品进行预处理,排除了辐照损伤对扩散系数测定的影响,从而测得砷在硅中本来意义下,即替位扩散意义下的本征扩散系数.如所预期,这组数据比国外直至目前所测得的数据要低.浓度剖面的实验数据由非线性扩散方程的数值解进行拟合.结果表明:SUPREM III所采用的模型在较高浓度区扩散系数随浓度递增速率较小,Hu理论仍然和本实验(?)较符合.本文还求得了扣除辐照损伤增强扩散效应后,砷在硅中的激活能为4.42eV     

Malformation of the tear ducts associated with clefts in the face (author's transl)

A case of malformation of the tear duct associated with clefts in the face is described. To our knowledge this combination has not been described before. The whole symptoms complex consisted of: bilateral cleft lip upper jaw and gum, choanalatresia, mucocele of the left nasal cavity from adhesions of the lower concha with the nasal septum, cystic dilatation of the tear sac at the connection to a bony naso-lacrimal duct. Right inguinal hernia, syndactyly of the first and second left toes, iris-chroid coloboma right with congenital cataract and unilateral right convergent squint. Because of the advanced dacryocystitis on the basis of the congenital dacryostenosis, and external dacryostorhinostomy (modified after Kaleff 1937) was performed after pre-treatment by instillation of antibiotic solutions in the tear ducts. At the same time the nasal cavity mucocele was opened by partial excision of the lower concha and opening the choanal atresia. After a post-operative course free of complications and with clear patency of the tear ducts the oral surgical operation was done--closure of the face clefts. The chromosome analysis was normal the only abnormal result here was an unexplained slow rate of multiplication of lymphocytes in four cultures inoculated at various points of time. Because we could not find any hereditary factors, this symptom complex is probably due to exogenous embryo damage during the early development phase.     

Reaction of foetal tissues to intra-uterine subcutaneous injection of barium sulphate

Subpannicular injection of sterile barium sulphate in newborn rabbits produces an acute inflammatory response which is clearly seen at 24 hr and is well established at 48 hr. The processes of repair has begun by the 4th day with the appearance of proliferating capillaries and fibroblasts. In rabbit foetuses both vascular and cellular components of the acute inflammatory response are more prominent and appear earlier than in newborn rabbits, being well developed within 24 hr. The process of repair also begins earlier, proliferation of capillaries and fibroblasts being already prominent by 48 hr. By the 4th day the lesion is compact, less cellular and relatively avascular.     

A de novo interstitial deletion of chromosome 15 band q25 as revealed by FISH-technique

We report a new chromosomal finding in a 20 month-old girl. The minor clinical features included: moderate mental retardation, microcephaly, mild hypotonia and hypertelorism. Initially, what appeared to be a terminal deletion of the long arm of one chromosome 15 [15q26-->qter] was determined to be an interstitial deletion involving band 15q25 as revealed by FISH-technique, showing the presence of intact telomeric hybridization signals. The cytogenetic diagnosis was thus modified to 46,XX, del (15) (pter-->q24::q26--> qter). Nevertheless, the function of the enzyme telomerase should not be ignored, as healing could occur following such terminal deletions. Consequently, it will remain a difficult task to distinguish terminal deletions from those that are interstitial.     

Intraoperative spinal sonography in the cervical anterior approach

Intraoperative spinal sonography was used during cervical anterior approach procedures for cervical discectomy and osteophytectomy to demonstrate spinal pulsation, the protruded disc or osteophyte, the anterior subarachnoid space, and the spinal cord. Spinal pulsation was recognized in some cases before removal of the disc but the anterior subarachnoid space and spinal cord could not be observed. However, the latter were more clearly observed during removal of the disc and could be seen after total removal of the disc and osteophyte. This method allows confirmation of decompression and pulsation of the spinal cord without cutting and removal of the posterior longitudinal ligament.     

Internal hazardous substance burden of persons from various regions of origin--studies of lead, mercury, arsenic and cadmium exposure

AIM OF THE STUDY: The aim of this study was to investigate the concentration of metals of environmental-medical relevance in biological materials in persons seeking asylum with regard to their country of origin. COLLECTIVE AND METHOD: During medical examination after entry into Germany of persons seeking asylum, samples were taken for determination of the following biological monitoring parameters: lead in blood, and arsenic, cadmium and mercury in urine. A total of 103 males were investigated (13 from former Yugoslavia, 29 from the former USSR, 33 Africans and 28 Asians) ranging from 16 to 53 years of age (median 27 years). 34 male Germans without occupational exposure to these substances and a similar age structure (age 25-36 years; median 26 years) served as a control group. RESULTS: The countries of origin had a significant influence on all the biological monitoring parameters investigated. The mean blood lead concentration in the Asians of 75.4 micrograms/L was the highest level found, while the lowest concentration of 38.0 micrograms/L was measured in the German controls. Also the level of arsenic excreted in the urine was on average much higher in the persons seeking asylum than in the German controls. In the Africans a mean level of 9.7 micrograms/g creatinine was reached. The Germans had the lowest arsenic concentrations in urine of 5.3 micrograms/g creatinine. There were, however, considerable interindividual fluctuations, which are probably due to oral uptake of arsenic compounds as a result of eating seafoods. The highest mean concentration of mercury excreted in urine was found in the German controls. Values of 0.9 microgram/g creatinine were determined. The men seeking asylum from former Yugoslavia had significantly higher values than other groups for cadmium excreted in urine. The median of 0.6 microgram/g creatinine was nearly three times as high as found in the Germans. CONCLUSIONS: For all parameters investigated, with the exception of mercury, higher internal exposure was found in the persons seeking asylum than in the German controls. This may be due to individual life style, dietary habits or environmental conditions in the country of origin. For clinical environmental medicine, the 95th percentile, as the upper limit of the reference range, can only be regarded as an orientation aid for classifying the exposure to hazardous substances of an individual compared to other persons from the same environment.