BaTiO3 thin-film waveguide modulator with a low voltage-length product at near-infrared wavelengths of 0.98 and 1.55 microm.

A BaTiO3 thin-film electro-optic waveguide modulator with a low half-wave voltage-length product has been demonstrated at near-infrared wavelengths of 1-1.6 microm. Half-wave voltage-length products as small as 0.25 and 0.5 V cm were measured for a 5-mm-long device at wavelengths of 973 and 1561 nm, respectively. The effective electro-optic coefficients were calculated as 420 pm/V at 973 nm and 360 pm/V at 1561 nm. Further improvements in device performance by optimizing the ferroelectric domain structure are anticipated.

[Complete removal of the rectum with preservation of continence in rectal cancer]. / Vollständige Rektumentfernung mit Kontinenzerhaltung bei Rektumkarzinom.

Restorative complete rectal excision with coloanal anastomosis was performed in 14 patients (12 cases with rectal carcinoma, i.e. 12% of a consecutive series). The pathologic stages were Dukes D in 3, Dukes C in 5, Dukes B in 2 and Dukes A in 2 patients. A simple technique of hand-sewn end-to-end endoanal anastomosis, following mobilization of the whole left colon in most cases, was employed. The postoperative course was uneventful in 11 of 14 cases, with protective colostomy in 1 patient only. 3 patients developed a presacral infection with a primary colostomy in 2 cases, and with early abdomino-perineal excision in 1 case. 1 patient with a doubtful distal margin and later recurrence refused amputation; salvage amputation became necessary in a patient with a large tumor situated 9 cm above the anocutaneous junction, who developed a locoregional recurrence by tumor implantation. Normal or satisfactory continence was recovered in all patients after a few weeks or months. Presupposing proper selection of cases and surgical technique, complete rectal excision with coloanal anastomosis is regarded as a very useful curative or palliative procedure in the treatment of rectal cancer.

Determination of total tin in geological materials by electrothermal atomic-absorption spectrophotometry using a tungsten-impregnated graphite furnace.

An electrothermal atomic-absorption spectrophotometric method is described for the determination of total tin in geological materials, with use of a tungsten-impregnated graphite furnace. The sample is decomposed by fusion with lithium metaborate and the melt is dissolved in 10% hydrochloric acid. Tin is then extracted into trioctylphosphine oxide-methyl isobutyl ketone prior to atomization. Impregnation of the furnace with a sodium tungstate solution increases the sensitivity of the determination and improves the precision of the results. The limits of determination are 0.5-20 ppm of tin in the sample. Higher tin values can be determined by dilution of the extract. Replicate analyses of eighteen geological reference samples with diverse matrices gave relative standard deviations ranging from 2.0 to 10.8% with an average of 4.6%. Average tin values for reference samples were in general agreement with, but more precise than, those reported by others. Apparent recoveries of tin added to various samples ranged from 95 to 111% with an average of 102%.

[Localized colitis cystica profunda]. / Colitis systica profunda localisata.

Colitis cystica profunda is a rare and benign disease of the colon and rectum, generally encountered in younger adults. It is characterized by submucous displacement of tubular glands, formation of intramural glandular cysts and fibromuscular obliteration of the submucosa. It is chiefly located in the rectum and usually has the clinical aspect of a tumor. Clinical pattern, etiology and diagnosis are described with reference to a personal case and 84 cases in the literature. It is emphasized that cancer must be ruled out (i.e rectal amputation is unnecessary in cystic colitis.