Further studies on polyamides from bisacid a2

Earlier work on the low temperature solution polyamidation of bisacid A2 has raised a number of structural problems. Work carried out more recently showed that the problem of apparent nonisostoichiometry could be reasonably satisfactorily explained. The present paper reports the synthesis and investigates the properties of a further series of polyamides based upon Bisacid A2. More importantly, however, a detailed characterization and evaluation of the new polymers with respect to their structures is presented. This enabled us to compare the various structures in the light of the experimental evidence provided by a number of analytical and spectroscopic techniques, solution behavior, molecular weight, and thermal, morphological, and mechanical properties. Some work was also done on the effect of incorporating a small amount of a trifunctional monomer into the polyamide system.     

The high-resolution time-of-flight spectrometer TOFTOF

The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of 10¹⁰n/cm²/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.     

p53 tumour suppressor gene mutations in benign prostatic hyperplasia and prostate cancer

OBJECTIVE: Seminal vesicle cysts combined with ipsilateral renal agenesis represent a rare urological anomaly. We searched the literature to review the clinical presentation, diagnosis and therapeutic treatment options of this anomaly. METHODS: A pooled analysis was performed of 52 cases of seminal vesicle cysts combined with ipsilateral renal agenesis, including our own observation. The evaluation included: patient age at diagnosis, race, laterality (R/L), presence of ureteral remnant in the cyst, presenting symptoms, diagnostic examinations, treatment and outcome. RESULTS: The mean age at diagnosis was 30.2 years. The majority presented in the 2nd, 3rd and 4th decade of their lives. Only 2 patients (4%) were of African origin, all others were Caucasians. The distribution R:L was 2:1. Ureteral remnants were present in 14 patients (27%). The most common symptoms were: dysuria (37%), frequency (33%), perineal pain (29%), epididymitis (27%), pain following ejaculation (21%) and scrotal pain (13%). Infertility was found in 9 patients (17%). The cyst was palpable by digital rectal examination in 79%. All patients underwent intravenous urography, and 88% underwent cystoscopy. Other frequently performed investigations are: ultrasonography (27%), CT scanning (27%), vasovesiculography (46%) and urethrocystography (23%). The final treatment was open surgery in 74%, aspiration in 6%, transurethral deroofing of the cyst in 6% and spontaneous rupture in 4%. In 6% no treatment was given and in 4% the treatment is unknown. All patients were free of symptoms after open exploration. The success rates after transurethral deroofing and aspiration were 75 and 30% respectively. CONCLUSION: Seminal vesicle cysts combined with ipsilateral renal agenesis are a rare urological anomaly, occurring in men in the 2nd to 4th decade of their life. They present with symptoms of bladder irritation and obstruction and with pain in the perineum and scrotum. Epididymitis is frequently found. The diagnostic work-up consists of a digital rectal examination, transrectal and abdominal ultrasonography, CT scan and a cystoscopy. Open surgery and transurethral deroofing of the cyst give excellent results (100 and 75% cure respectively). Aspiration of the cyst should only be used for diagnostic purposes.     

Analysis of grain boundary movement analogous to dislocation movement – both with a matrix having precipitates

In the present investigation it has been shown exemplarily for an austenite microstructure containing carbonitrides that the specific restraining force of a grain boundary due to the distribution of precipitates can be described by a modified Orowan's law, so that the grain boundary movement is considered to be analogous to the dislocation movement. This is achieved by using a modified restraining force F_r (corresponding to the cubic geometry of the particles), a detailed thermodynamic analysis of the precipitates (in this case, carbonitrides) and selected relation for the interparticle spacing L_a. The specific restraining force and the interparticle spacing depend on temperature within the austenite range. Each temperature is attached to a couple (F_r/L_a). The plot F_r against shows straight lines for each steel and from their average slope, a shear module G' of grain boundaries, which is about 64300 N·cm^?2, is obtained. Hence, it is possible to describe the specific restraining force of a grain boundary with the help of Orowan's law or as it is conventionally done by using Zener's modell. At a critical temperature T*, which is different for each steel, the specific restraining force is equal to the driving force of the grain boundary. The corresponding values of L_a are also different for each steel and the steel which is the most resistant to grain coarsening is allowed to have the greatest value of L_a which still retains the capacity of impeding grain coarsening.     

Integration of medical responsibility

The article describes responsibility as a term with six relations and four different levels. It analyses the conflicts between different addresses, levels and values and emphasizes the need to integrate the responsibilities of the physician. The term "responsibility" provides a more differentiating analytical tool for conflicts in medical acting than the so-called "principles of biomedical ethics".     

Die Relevanz einer institutionalisierten Ethik für eine professionelle Zahnmedizin

Definition of the problem

The concept of “ethics” has recently been incorporated into both the 2014 Model Professional Code for Dentists and the current version of the “National Competence-Based Catalog of Learning Objectives in Dental Medicine” (NKLZ, Nationaler Kompetenzbasierter Lernzielkatalog Zahnmedizin). The study presented here addresses the question which relevance this has for the relevance of the new concept accomplished for the dental profession and society.

Arguments

To this end, the societal processes that are related to the autonomous freedom of action of the dental profession are discussed. Therefore the sociological fields of discourse such as profession (and the effect of its constitutive antinomies), trust, education, expertise, practice of treatments and sanction are reviewed for their potential of having connections to each other and serving as a structural frame concerning an ethically reflected acting of the professional. The basis of the professional freedom of action is the trust of society and the individual patient in the professionally acting dentist.

Conclusion

The study arrives at the conclusion that it was a serious omission for many decades not to make young dentists aware of the ethical foundations of dental activity on an institutionally established basis and thus failing to encourage them to constantly reflect their professional expertise in relation to the problems to be solved. This deficit has now been identified. It is absolutely essential to implement an institutionalized structure dealing with ethical questions within the scope of dental medicine.

     

Spatial distributions of O2, CO2 and SO2 in a pilot-scale fluidized bed combustor operated with different coals

Axial concentration profiles of O₂, CO₂ and SO₂ have been measured at different radial positions in a coal-fired fluidized bed combustor. The profiles show some spatial inhomogeneity in the bed, the degree of which depends on fluidizing velocity and amount of excess air. Comparison of SO₂- with CO₂-concentration profiles reveals that SO₂ is formed in proportion to CO₂ only with anthracite as fuel. With bituminous coals, SO₂ is preferentially formed near the coal feed point. These results are discussed with regard to characteristic times of mixing and chemical reaction in fluidized beds, and SO₂-formation characteristics of the employed coals obtained in a thermobalance.