Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion – Laser Beam

Magnesium alloys are biocompatible, biodegradable and have the ability to promote bone ingrowth, making them ideal candidate materials for replacing auto- and allografts in future treatments of large bone defects. Powder bed fusion–laser beam (PBF-LB) additive manufacturing of these alloys would further allow for the production of complex structures, optimized for bone grafting. However, the corrosion rates of structures processed by PBF-LB remain too high. An improved understanding of the influence of the microstructure generated during PBF-LB on the corrosion properties is considered key to their future implementation in implants. In this study, the effect of PBF-LB processing and subsequent hot isostatic pressing (HIP) on the microstructure and texture in different sample directions was studied and related to the corrosion behavior of a Mg-Y-Nd-Zr alloy. The results were compared with an extruded Mg-Y-Nd-Zr alloy. A higher amount of secondary phases resulted in a higher rate of localized corrosion for the PBF-LB processed material compared to that for the extruded one. Due to growth of the secondary phases, the corrosion rate was further increased after HIP. Moreover, a strong texture was observed in the PBF-LB material, and it was also enhanced in the HIP material. While this affected the electrochemical activity as measured by potentiodynamic polarization tests, any texture effect appeared to be masked by the contribution of the secondary phases in the longer-term mass change and hydrogen evolution tests. Future work should look further into the influence of individual process parameters on the microstructure and the resulting corrosion behavior of the material, to further clarify its interdependence.

Release of Side-Chain Fluorinated Polymer-Containing Microplastic Fibers from Functional Textiles During Washing and First Estimates of Perfluoroalkyl Acid Emissions

The quantity and composition of fibers released from functional textiles during accelerated washing were investigated using the GyroWash method. Two fabrics [polyamide (PA) and polyester/cotton (PES/CO)] were selected and coated with perfluorohexane-based side-chain fluorinated polymers. Fibers released during washing ranged from ∼10 to 500 μ with a similar distribution for the two textile types. The PA-based fabric released considerably more fibers >20 μm in length compared to the PES/CO-based fabric (>1000/GyroWash for PA vs ∼200/GyroWash fibers for PES/CO). After one GyroWash (2-15 domestic washes), fibers that contained approximately 240 and 1300 μg total fluorine per square meter (μg F/m²) were released from the PA and PES/CO fabrics, respectively. Current understanding of the fate of microplastic fibers suggests that a large fraction of these fibers reach the environment either in effluent wastewater or sewage sludge applied to land. In the environment, the fluorinated side chains will be slowly cleaved from the backbone of the side-chain fluorinated polymers coated on the fibers and then transformed into short-chain perfluoroalkyl acids. On the European scale, emissions of up to ∼0.7 t of fluorotelomer alcohol (6:2 FTOH) per year were estimated for outdoor rain jackets treated with fluorotelomer-based side-chain fluorinated polymers.

[Results of percutaneous radiotherapy of localized prostatic carcinoma (author's transl)]

Analysing preliminary results of percutaneous radiotherapy on 79 patients with localized prostatic carcinoma, the uncorrected five-year survival rate of all patients was 67.3%, that in stage O, A and B 89.5% and that of patients in stage C and D 64.5%. The tumour-free five-year survival rate of all patients was 50.2%. In three patients there was a recurrence (4%), in four others severe side-effects (5%). There were no fatal complications. Radiotherapy can be considered to be an alternative to operation even when the tumour is limited to the prostate.

Ureteral replacement with a new prosthesis

A new flexible silicone ureteral prosthesis has been developed and implanted by a new technique in 20 miniature pigs. The improved implantation technique and the results are described. All prostheses remained firmly attached in their position and drained the upper urine collecting system adequately during an observation period up to 12 mos. Leakage, incrustation, dislocation or rejection did not occur. The promising results encouraged us to continue our investigations to get long term experience for clinical trial in human patients for whom nephrostomy is the alternative.

Epidemiological events surrounding a paralytic case of poliomyelitis in Sweden

A case of clinical poliomyelitis occurred in Sweden in January 1977; it was the first indigenous case in Sweden since 1962. This incident was of particular interest as it provided an opportunity to study the spread of virus in a cluster of unvaccinated persons and in individuals more or less fully vaccinated with inactivated vaccine. The patient excreted wild type 2 virus and the same type was isolated from 25 other individuals, all of whom were close contacts of virus excretors. Among the close contacts, 14 of 20 unvaccinated preschool children were found to excrete virus, but excretion was not found in any of the 7 vaccinated children examined.

[Value of lymphography in teratoid testicular tumors (author's transl)]

In 72 patients with malignant testicular tumors lymphograms were reviewed and correlated with the microscopic findings of the resected lymphnodes. In 55 patients (76%) the roentgenographic diagnosis was confirmed by histology. In 6 patients lymphography was false positive as microscopic examination of the resected lymphnodes showed. In 4 patients lymphography was considered negative but metastatic disease proven microscopically from retroperitoneal lymphnodes. Out of 7 patients with questionable positive lymphograms 2 had retroperitoneal metastases confirmed by microscopic examination. The limits, errors and value of lymphography in patients with testicular tumors are discussed.

[Urinary calculi in children (author's transl)]

From a total of 274 children with urinary calculi, 192 cases were analyzed. 63% of these were male. In 19% a familiar disposition was noticed. Phosphate containing stones were found in 81%. Most of these had an urinary tract infection caused by urea splitting organisms. There was no correlation between the chemical composition of the stones and infection with coli and enterococci. One-third of the analyzed cases exhibited malformations of the urinary tract. Of these, 92% had urinary infections due primarily to urea splitting bacteria. This infection rate was markedly higher than in the children without combined malformations of the urinary tract. The peak incidence was around 2 years of age. In the last group symptoms were atypical but more severe than in those cases without malformations of the urinary tract.

[Instrumental urological diagnostic procedures in infancy and childhood (author's transl)]

Instrumental investigations with catheters, bougies and endoscopes are important to diagnose urological diseases in children. Possiblities of the instrumental procedures and the value of endoscopy in the diagnosis of vesico-ureteral reflux are demonstrated.

[Benign and malignant tumors of the prostate (author's transl)]

Etiology, symptoms, diagnosis and treatment of carcinoma of the prostate and benign prostatic adenoma are discussed. In prostatic adenoma the treatment of choice is either open surgery or transurethral resection. Conservative medical treatment has not been successful. The decision between radical prostatectomy, radiotherapy, or hormonal treatment in prostatic carcinoma depends on the staging results of the disease including-if necessary-diagnostic lymphadenectomy.

[Ureteroureterostomies: indications and results (author's transl)]

Thirteen unilateral ureteroureterostomies and twenty-five transureteroureterostomies (TUU) were performed since 1968. In 22 of these, a transureteroureterocutaneostomy (TUUC) was done. Indications, operative procedures, results and complications are discussed. No complications due to the anastomosis were found. In six cases stenosis of the ureterocutaneostomy was demonstrated which, in four instances, made another form of urinary diversion necessary. Ureteroureterostomies should only be performed with well functioning kidneys and with one well preserved ureter. TUUC is recommended in cases with at least one dilated ureter.

Results of 89strontium therapy in patients with carcinoma of the prostate and incurable pain from bone metastases: a preliminary report

The therapeutic application of 89strontium for the relief of pain in 11 cases of carcinoma of the prostate with skeletal metastases is reported. A significant clinical improvement could be observed in 8 of the 11 patients with generalized osseous metastases of prostatic carcinoma after the application of 30 muCi. 89strontium per kg. The effect was long lasting. At the same time an increase of alkaline phosphatase was observed, which was interpreted as an indication of the reactivation of osteoblasts and osteoid peripheral zones owing to beta-emission of the radioisotope in the affected areas. The indications for such therapy are discussed.

[Embryonal rhabdomyosarcoma of the urinary bladder in childhood. Report of five own cases]

Malignant lesions of the bladder in infancy and early childhood arise from mesenchymal tissue. Among the mesenchymal tumors embryonal rhabdomyosarcoma is more common in young children than in adults. The gross appearance of rhabdomyosarcoma of the bladder is typically that of polypoid grapelike clusters of tissue, termed "sarcoma botryoides". Histologically, the lesion is consistent with embryonal rhabdomyosarcoma. The growths originate in the submucosal layer of the trigone and the internal urethral orifice. Rhabdomyosarcoma (RMS) of the bladder in children tends to remain within the disease. Deep extension and metastasis to regional lymph nodes and to distant sites is a relatively late occurrence. The symptoms are characteristically those of obstruction and strangury. Hematuris is uncommon. The intravenous urogram shows characteristic lobulated filling defects. Treatment of choice is almost always total cystectomy. Suprapubic cystotomy must be prohibited both as a method of drainage and as an approach for biopsy since tumors ulcerating through the abdominal wall after cystotomy and local excision have been observed. With concomitant administration of radiation therapy in selected cases and the combination of surgery with multiple drug chemotherapy, promising results have been obtained in the therapy of embryonal RMS of the bladder in children.

[Anastomoses of the urinary tract for treatment of duplicated ureters (author's transl)]

Anastomoses between the kidney pelves or the ureters are excellent operative procedures to correct duplications of the urinary tract in distinct cases. Heminephrectomy may be avoided, when only one of the ureters is affected and the parenchyma of both portions of the kidney is intact. Indications are megalureter, recurrent refluxes, ureteroceles and ectopic ureteral orifice. The operative technic used in 13 cases is described. Advantages and disadvantages are discussed.