Manganese release linked to carbonate dissolution during the start-up phase of a subsurface iron removal well in Khabarovsk, Russia.

Subsurface iron removal (SIR) is a proven pre-treatment technology for removing dissolved iron and manganese from groundwater. The start-up phase of a SIR well and the proper development of the reaction zone around the well are crucial for its subsequent performance. This study evaluates the start-up phase of a SIR production well in Khabarovsk, Russia during the first 194 SIR cycles. A strong release of manganese was observed, which led to concentrations twice as high as the background value of the pristine groundwater. Regular monitoring of the production well and its three adjacent observation wells showed that iron removal began immediately after start-up and that the reaction zone was completely formed within 25 SIR cycles. Closed-bottle batch tests and a flow-through leaching test revealed that the grain size of the aquifer material and groundwater pH are the primary controls on manganese release. During infiltration phases the dissolution of manganese-bearing carbonate minerals was caused by direct oxidation by O2, whereas the low groundwater pH of 6 seemed to be responsible for the manganese release during extraction.

[Analysis of reproductive parameters in mare herds of the chief and state stud farms at Marbach and Schwaiganger]. / Analyse der Fortpflanzungsparameter in den Stutenherden der Haupt- und Landgestüte Marbach und Schwaiganger.

The paper analyses different parameters of fertility in mares of different breeds. Totally 2794 cycles of the years 1973 to 1985 have been investigated.

[Scanning electron and light microscopic studies of the surface epithelium of the rete testis and epididymis in the boar. II. Ductus epididymis]. / Rasterelektronen- und lichtmikroskopische Untersuchungen des Oberflächenepithels von Rete testis und Nebenhoden beim Eber. II. Ductus epididymidis.

The entire ductus epididymidis is characterized by pseudostratified columnar epithelium which contain principal and basal cells. Apical cells are found in the proximal segments. Long stereocilia projected from the apical surface of the principal cells. Signs of adjacent apocrine secretory activity are shown. The various segments of the ductus epididymidis present differences in the height of the epithelium, the development of the stereocilia, the appearance of granules in the cytoplasm, the luminal sperm concentration and the height of the peritubular layer.

[Scanning electron and light microscopic studies of the surface epithelium of the rete testis and epididymis of the boar. I. Rete testis and efferent ducts]. / Rasterelektronen- und lichtmikroskopische Untersuchungen des Oberflächenepithels von Rete testis und Nebenhoden beim Eber. I. Rete testis und Ductuli efferentes.

The use of the scanning electron microscope gave a three dimensional representation of the epithelial surface. Additionally, light microscopy revealed the representative structure of the epithelium. The rete testis showed a single layer of cubic epithelial cells. Short and dense microvilli were found on the surface. Sporadically a single, cilia-like structure was recognized. An extratesticular rete testis was identified. The flowing transition of the epithelium between the rete testis and the efferent ductuli occurred at different levels, so that both kinds of epithelial structures were recognized in the same area. The efferent ductuli were composed of a single columnar epithelium consisting of two cell types, principal cells and ciliated cells. The ciliated cells were recognized by their cilia protruding into the lumen. The principal cells showed microvilli on their surface and bleblike apical protrusions which erupt into the lumen.

Scanning electron-microscopic study of sperm retention and migration in the vagino-cervical region of the rabbit.

The pattern of sperm retention and migration in the vagino-cervical region of rabbit was studied by means of scanning electron microscopy. The following phenomena were observed: 1) Spermatozoa located in the vagina and at the orifice of the ectocervix are usually distributed diffusely. They appear to be resting on the epithelial surface; many are structurally abnormal or decapitated. 2) The great majority of spermatozoa, however, seems to be anchored or retained in narrow epithelial channels with their heads in close file formations. This phenomenon was observed particularly in the fornix vaginae as late as 24 h post coitum. 3) A great number of spermatozoa invading the cervix evidently migrates in groups along the mucosal surface. Their heads are oriented toward the uterus and contact the epithelial cells. Spermatozoa that migrate beyond the cervico-uterine junction are distributed in the same manner. 4) Spermatozoa colonizing the cervical crypts appear to be attached via the anterior margins of their heads to the epithelial cells or to the tips of kinocilia. Their tails project into the crypt lumen. It is suggested that mainly three factors may be responsible for these phenomena: (i) the fact that only motile spermatozoa overcome the vagino-cervical barrier; (ii) the tendency of spermatozoa to move along the mucosa in close vicinity to the epithelial cells; and (iii) the inability to recognize mechanical barriers on the migration route (e.g., cervical crypts) and to overcome them quickly. This may be one of many possible causes leading to sperm retention in the vagino-cervical region.