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Background The bicuspid aortic valve (BAV) frequently requires surgical intervention for aortic regurgitation (AR) and aneurysm. Valve-preserving surgery for BAV has evolved over the last 25 years. Methods This review summarized experience in BAV repair with a special focus on predictors of failure and specific surgical techniques addressing them. Results Excellent repair stability can be achieved if a standardized approach addressing all pathologic components of aortic valve and root is used. Anatomic variations must be addressed with special approaches. Conclusions Today, BAV repair leads to excellent stability if an anatomy-oriented concept is used. Further improvements of cinical results and reproducibility can be anticipated.

Valve preservation or repair of the regurgitant bicuspid aortic valve (BAV) minimizes valve-related complications. The purpose of the current analysis was to determine the proportion of BAVs than can be repaired. Between 2000 and 9/2018, 1168 operations for BAV without stenotic pathology were performed. Of these, 103 underwent isolated aortic valve replacement, the remaining 1055 individuals underwent valve repair. Reasons for replacement were analyzed. The proportion of repaired BAVs remained constant at 85% over the years. The most frequent reasons for replacement were cusp calcification or active endocarditis. In only 2 instances, replacement was performed as intraoperative conversion after failed repair. The vast majority of BAVs can be repaired with good durability as long as cusp substance is preserved.

Valve-preserving aortic root replacement has become an attractive alternative to composite replacement leading to better quality of life and minimal valve-related complications. Root remodeling requires less surgical dissection and has been shown to lead to more physiological hemodynamics compared to valve reimplantation. Over the last 2 decades, improvements have been made regarding assessment of cusp and root configuration. Aggressive correction of cusp prolapse extended the application of root remodeling to a larger patient population and has markedly improved valve stability, even in patients with connective tissue disorders. In the presence of annular dilatation, the addition of an annuloplasty has been shown to be beneficial for valve competence and repair durability. Aortic root remodeling combined with cusp repair and correction of annular dilatation leads to excellent valve stability and minimal valve-related complications.

Background Previous experience with repair of the regurgitant bicuspid aortic valve (BAV) has shown a strong influence of commissural orientation on repair durability. We have modified commissural orientation by asymmetric plication of the fused sinuses. We analyzed the results of the modified technique. Methods Between 2009 and 2014, 35 patients with BAV and commissural orientation of no more than 160° underwent aortic valve repair, including plication of the fused sinuses and circular annuloplasty. The control group consisted of 21 historic controls undergoing operations between 2000 and 2008 but without sinus plication; subcommissural plication was used as annuloplasty. The groups were similar in most respects; differences existed in preoperative annular diameter, prevalence of complete fusion, use of a pericardial patch, and plication of the fused cusp. Results At discharge the degree of aortic regurgitation (AR) was significantly lower in the study group ( p = 0.004). Survival after 5 years was 100% in the study group and 95.2% in the control group after 5 and 10 years. Five-year freedom from reoperation in the study group was 93.0% and 57.1% in the control group ( p = 0.0013); freedom from valve replacement was 95.8% and 79.3% ( p = 0.036). Freedom from recurrent AR grade II or higher was 67.1% in the study group and 33.3% in the control group ( p = 0.0024). Mean postoperative peak gradient was significantly lower in the study group (14.3 ± 6.5 mm Hg versus 28.9 ± 18.5 mm Hg, p = 0.003). Conclusions Plicating the fused sinuses and thus reducing root circumference in the fused part changes commissural orientation of the BAV which leads to better short- and midterm stability in BAV repair.

Repair has become an alternative to replacement for bicuspid aortic valves that require surgery for regurgitation with left ventricular volume overload or aortic aneurysm. Over the past 15 years, improvements have been made regarding assessment of valve configuration and annular stabilization. Even though 20-year stability has been achieved in a relevant proportion of repaired bicuspid aortic valves, the new aspects have markedly improved short- to mid-term results and can be expected to lead to true long-term repair stability. In the presence of preserved root dimensions, isolated cusp repair techniques for correction of prolapse are sufficient. Circumferential annuloplasty has become an important part of the procedure. In the presence of root dilatation, root replacement not only eliminates the root pathology but also contributes to valve stability. Almost always cusp repair is also required.

Aortic valve replacement using a pulmonary autograft is an accepted option in children and young patients. The use of a pulmonary valve with congenital anomaly as autograft is controversial. We describe a case in which a quadricuspid pulmonary valve was used as an autograft in childhood. The patient presented with severe regurgitation 13 years later. Repair was performed with stabilization of the root and cusp prolapse correction, leading to normalized valve function. Despite concerns over the long-term durability of an anomalous pulmonary valve as autograft, good mid to long-term results can be achieved.

Coronary artery fistulae and coronary aneurysms are rare anomalies. When they become symptomatic, they require precise anatomic information to allow for planning of the therapeutic procedure. We report a case in which both fistulae and aneurysm were present. The required information could only be obtained by electrocardiogram-gated computed tomography with reformation. This imaging modality should be considered in every case of fistula or coronary aneurysm.

The industrial production of personalized goods is a great opportunity for manufacturing companies to strengthen their competitive position. This requires a very high degree of flexibility in the whole value-adding system. The massive digitization of production enables this flexibility in an economic way. There are manifold new solutions arising from the fields of the Internet of Things and Industrie 4.0. The strong connection of the physical, the service and the digital world can improve the quality of information required for planning, optimization and operation of manufacturing systems. Therefore, cyber-physical systems can be used in manufacturing to follow the vision of producing personalized goods on a large scale. The contribution at hand introduces the Application Center Industrie 4.0. This environment is a highly advanced platform for the cooperative research and development of innovative cyber-physical production systems between the IFF at the University of Stuttgart, the Fraunhofer IPA and cutting-edge manufacturing companies. The paper provides a detailed overview over the concept of the Application Center Industrie 4.0. The IT platform Virtual Fort Knox is concisely described as it serves as a backbone to realize a safe, secure and flexible way to integrate all relevant data and information sources and sinks. This includes humans, IT-Systems and technical components. This concept is then substantiated by the introduction of selected, prototypically implemented demonstrators that offer new ways of understanding and operating manufacturing systems. Afterwards the first example of a strategic cooperation between the Fraunhofer IPA and TRUMPF will be introduced. The paper closes with a summary and an outlook of future activities in the area of the Application Center Industrie 4.0.

A novel integrated approach to high-accuracy machining with industrial robots is presented in this paper. By combining a conventional industrial robot with an external compensation mechanism, a significantly higher bandwidth of the control of the relative position between the tool and the workpiece can be achieved. A model-based feedback controller for the compensation mechanism, as well as a mid-ranging control architecture for the combined system with the robot and the compensation mechanism are developed. The system performance is evaluated in extensive machining experiments, and the workpiece accuracies achieved are quantified and compared to the corresponding results obtained with state-of-the-art approaches to robotic machining. It is shown that the proposed approach to machining offers significantly higher accuracy, up to eight times improvement for milling in steel, where the required process forces, and thus the exhibited position deviations of the robot, are significant.

This paper proposes an approach for a 3D-Piezo Compensation Mechanism unit that is capable of fast and accurate adaption of the spindle position to enhance machining by robots. The mechanical design is explained which focuses on low mass, good stiffness and high bandwidth in order to allow compensating for errors beyond the bandwidth of the robot. In addition to previous works [7,9], an advanced actuation design is presented enabling movements in three translational axes allowing a working range of each axis up to half a millimeter. Based on the presented theoretical dimensioning and finite element simulation translational moves with higher bandwidth can be enabled, due to the parallel design approach of a 3D-Piezo Compensation Mechanism. For realization aspects piezo actuators are chosen due to their fast dynamics and high forces. The realization of the control loop is further outlined. In order to enable a good control performance the set-up of sensing the extension of the piezo actuator is detailed as well as the spindle position used in fast real-time environment. As a result the 3D-Piezo Compensation mechanism unit allows an active adaption of the spindle position in the range of micrometers. A description of the deployment of the compensation unit to a robot machining system as well as first experimental results conclude the paper and prove the proper functioning of the approach and outline the potential of the entire system. Measured robot paths are applied to the compensation unit and analyzed with respect to the reduction of robot path errors.

Summary Women‘s football is becoming increasingly popular both national and international. Exercise physiology characteristics describe increasingly conditional requirements. According to the amount of training and training intensity, cardiac adaptations can be observed. If higher workload is performed by top-class football players in additional international games, changes in the immune system are observed too. Due to this, adequate recovery time must be assured. In clinical daily routine the assessment of the iron metabolism is of great importance. Although the female athlete triad components (eating disorder, menstrual dysfunction and osteoporosis) occur less compared to other sports, attention should be paid to these characteristics in sports medicine examination.

Summary Further match analysis and observations were performed in soccer in recent years. During soccer matches female and male players cover a total running distance about ±10km, which is unchanged for many years. The amount of high-intensity activities during soccer matches shows significant differences between the levels of competition in both sexes. The comparison of conditional abilities between female and male teams from the first German soccer league show significant differences in linear running speed (30m -14.7%, p≤.05), nonlinear running speed (FLT-Z-Run-Sprint 22m -9.4%, p≤.05), jump performance (squat jump -32.1%, p≤.05, counter movement jump -33.8%, p≤.05) and endurance performance (lactate threshold test, running velocity at 4 mmol/l [km/h] blood lactate concentration -8.9%, p≤.05; ISRT -37.0%, p≤.05). With the exception of the dorsal trunk muscles in favor of women (dorsal trunk muscles +27.3%, p≤.05), no significant differences in trunk strength were found between women and men. Significant correlations were found between the total running distance at the Interval-Shuttle-Run-Test and the running velocity at 4 mmol/l blood lactate concentration in women from the first German league (r=0.87, p≤.05) but not in men from the fourth German league (r=0.47, p=n.s.). The current findings show that the general development in soccer matches has to be reflected by the methodology of performance assessment. Success in playing soccer requires resources, which are beyond the conditional abilities and are displayed in a new model.

The lack of annular stabilization is the drawback of aortic root remodeling, and recently the addition of annuloplasty has been proposed. Limited data, however, exist on late annular size after remodeling. We studied annular size over time.In 241 patients (53 ± 16 years) annular size was determined preoperatively (T0), before discharge (T1), and at least 2 years after remodeling (T2, 54 ± 27 months) with (n = 52) or without external suture annuloplasty. Seventeen patients had Marfan syndrome (7%), 100 a bicuspid valve (41%), and 22 acute dissection (9%). Mean graft size was 25.2 ± 1.3 mm, and annuloplasty size 24.3 ± 1.4 mm.Annular size was significantly reduced after repair and remained stable over time (T0: 27.4 ± 3.0 mm, T1: 24.2 ± 2.5 mm, T2: 24.2 ± 2.6 mm). After propensity-score matching (n = 33 each), baseline annular size was similar (with annuloplasty vs without: 28.7 ± 4.1 mm vs 27.8 ± 2.8 mm). Annular reduction was less effective without annuloplasty (23.9 ± 2.0 mm vs 25.6 ± 2.2 mm, P .01); size was identical at follow-up (23.8 ± 2.2 mm vs 25.1 ± 2.5 mm, P = .03). After matching, freedom from annular size increase10% at 4 years was 93 ± 5% without annuloplasty and 91 ± 9% with annuloplasty (P = .92). A linear mixed-effects model identified no significant effect of annuloplasty on annulus diameter change at T2 (P = .48). Era after 2004, Marfan syndrome, and smaller annulus diameter at discharge were the independent predictors for late annular expansion.Aortic annulus rarely dilates over time after remodeling. In the case of annular dilatation, annuloplasty normalizes annular size and may prevent further dilatation by enhancing cusp coaptation. Even without annuloplasty, the aortic annulus becomes smaller compared with preoperative dimensions when aortic valve remains competent.

We demonstrate a controlled phase change of p in a degenerate superposition by altering a laser frequency by only 10 MHz. The method relies on the preparation of an adiabatic state involving the M = ±2 and M = 0 states of the 3 P2 (J = 2) level of metastable neon. Dependent on the frequency, the preparation proceeds either by stimulated Raman adiabatic passage (STIRAP) or by coherent population trapping (CPT). In the former case the superposition is prepared by adiabatic transfer induced in an extended tripod linkage scheme. In the latter case population is optically pumped into the Zeeman manifold of the level 3 P2. The population which does not reach a dark state decays to the ground state of neon. The amplitudes and relative phases of the dark states differ for the two cases. The phase change is monitored using the method of phase-to-population mapping. 2006 Elsevier B.V. All rights reserved.

The behavior of ordinary concrete and high strength concrete under a combinative effect of stress and chemical corrosion was studied in the present work. The concrete specimens were immersed in a variety of chemical solutions including 10%, 5%, 1% and 0.1% ammonium nitrate and simultaneously subjected to different flexural loads with load levels of 30%, 40% and 50% of their initial flexure strengths. The influences of the concentration of solutions, quality class of the concretes and load level of applied flexural stress on the strength of concretes were investigated. The relationships between life-time of the concrete and concentration of the solution, relative strength of the concrete and penetration depth of the ammonium nitrate solutions were determined. The mechanisms of stress corrosion of concrete exposed to ammonium nitrate solution and superimposed to a flexural stress was also discussed.

Zusammenfassung Nach Ausschluss anderer Ursachen des vorderen Knieschmerzes kann mit einer intraossaren Druckmessung plus Schmerzprovokationstest bei einem Teil der Patienten die Symptomatik objektiviert und klassifiziert werden. Patienten mit einem erhohten intraossaren Druck (> 25 mmHg) und einem positiven Schmerzprovokationstest (= Hypertensionssyndrom der Patella) werden mit einer minimal-invasiven distalen Patelladekompressionsbohrung behandelt. Bei 27 Patienten mit therapieresistenten vorderen Knieschmerzen konnte eine Reduktion in der visuellen Analogskala von 7,6 auf 2,0 cm bei einem Follow-up von 3 Jahren dokumentiert werden.

Aim The goal of this study was to determine whether or not the intraarticular administration of hyaluronic acid can improve functional parameters, such as isokinetic muscle strength or total work and clinical test results in patients with osteoarthritis (OA) of the knee. Method As part of a prospective, controlled study 43 patients with osteoarthritic changes of both knees (radiographic Kellgren stage II–III) were followed in a right/left comparison. The influence of intraarticularly injected hyaluronic acid (20mg hyaluronic acid/2ml Hyalart ® ) on functional and clinical parameters was analysed. We used the isokinetic system Cybex 600 for measuring maximal isokinetic muscle strength and total work. A total of 20 males and 23 females fulfilled the inclusion criteria with an age between 55–78 years and underwent five injections of hyaluronic acid (one injection per week). The injected knee represented the treatment group, while the contralateral knee served as the control. Results The maximum peak torque of the knee extensors in the treatment group was measured between 57±26.15/32.33±19.63Nm prior to the injections and 77.17±32.54/47.83±21.43Nm following the hyaluronic acid therapy ( P 0.01). The analysis of the knee flexors at angular velocities of 60°/s and 180°/s revealed values of 40.44±21.58/22.89±16.64Nm and 53.55±24.26/34.05±17.37Nm ( P 0.01) respectively. The evaluation of the total work of the knee flexors and extensors revealed a significant difference ( P 0.01) between the treatment and control group. The Lequesne score was reduced from 13.57±1.88 prior to the injections to 7.94±2.53 after the treatment ( P 0.01). The pain score was documented with the help of a visual analog scale. The VAS values were reduced at rest from 3.83±1.72cm to 1.36±1.42cm and during weight bearing from 7.57±1.34cm to 3.75±1.32cm in the treatment group ( P 0.01). Conclusions This controlled prospective clinical trial confirmed that 5 weekly intraarticular injections of HA (Hyalart ® ) in patients with OA of the knee provide pain relief and functional improvements. Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved .

Sixteen paired human cadaver femora were prepared using conventional broaches. Cancellous bone was irrigated with 1 L pulsed lavage in one femur and 1 L syringe lavage in the contralateral femur. The specimens were embedded in specially designed pots, and vacuum-mixed bone-cements were applied in a retrograde manner. After application of a standard pressure to the pots, the femora were removed and radiographed, and horizontal sections were obtained and analyzed to assess cement penetration into cancellous bone and the ratio of the area of supported to unsupported cancellous bone (Rcb). Our results show that in equal quality bone, the use of jet lavage yields significantly (P < .0001) improved cement penetration and Rcb compared with syringe lavage specimens. Jet lavage should be considered routine to achieve interdigitation with cancellous bone in cemented total hip arthroplasty.

This paper describes the behavior of high-performance concrete under both chemical attacks and mechanical stresses. The specimens of the concrete C80 and C95 were subjected to flexural loads with a level of 30% of their initial strengths and immersed into a 5% ammonium sulfate solution, a 10% ammonium nitrate solution, and water saturated with Ca(OH) 2 , respectively. The development of strength of the concrete was determined at certain time intervals. The simultaneous action of corrosive media and mechanical stresses on the concrete leads to a stress corrosion effect. The difference of strength of the specimens, which were immersed in the water saturated with Ca(OH) 2 and the salt solutions and subjected to the same loading conditions, is defined as a chemomechanical effect (CME). The difference of strength of the unloaded and loaded specimens, both of which were immersed in the same salt solutions, is defined as a mechanochemical effect (MCE). The CME and the MCE of the concrete are discussed in the present paper.

Posttraumatic avascular necrosis of the femoral head typically occurs immediately or within a few years after a femoral neck injury, and non-traumatic avascular necrosis is often related to systemic glucocorticoid therapy. We report an unusual case in which avascular necrosis of the femoral head occurred 15 years after a transcervical femoral fracture in a woman with a 20-year history of daily inhaled glucocorticoid therapy for chronic bronchitis. She had not taken glucocorticoids by any other route and had no other risk factors for osteonecrosis. To our knowledge, this is the first report of osteonecrosis associated with inhaled glucocorticoid therapy in a patient with a local cause of diminished vascular reserve. Inhaled glucocorticoid therapy should be added to the list of risk factors for osteonecrosis.

Resume L’osteonecrose aseptique post-traumatique de la tete femorale se presente typiquement comme une complication survenant rapidement ou dans les premieres annees suivant une lesion du col du femur. Par ailleurs, la corticotherapie constitue la principale etiologie des osteonecroses non traumatiques. Nous rapportons l’observation d’une patiente ayant presente, 15 ans apres une fracture du col du femur, une osteonecrose de la tete femorale. Par ailleurs, elle etait traitee depuis 20 ans pour une bronchite chronique, par une corticotherapie inhalee a doses habituelles, sous la forme de beclometasone dipropionate. Il n’existait pas d’autres facteurs etiologiques de l’osteonecrose. Dans la mesure ou il n’existe pas d’observation rapportee dans la litterature d’osteonecrose secondaire a une corticotherapie inhalee, nous pensons qu’il s’agit la du premier cas d’osteonecrose non traumatique secondaire a une corticotherapie inhalee chez une patiente ayant une vascularisation osseuse probablement fragilisee. La corticotherapie inhalee devrait donc etre envisagee comme cofacteur dans le risque de survenue d’osteonecroses aseptiques.

Electron cyclotron resonance heating (ECRH) at the W7-AS stellarator is performed two systems of comparable heating power at 70 GHz (0.8 MW, 3 s) and 140 GHz (0.9 MW, 0.4 s). Experiments with 140 GHz open a new parameter window with high density operation up to 1.1 × 1020 m−3. H mode transitions were observed in high density discharges at 2.5 T and at lower density at 1.25 T. The operational window for the stellarator H mode with emphasis on the density and power threshold and the influence of gas puffing on the H transitions are discussed. Perturbation experiments with modulated ECRH power were performed to determine the heat transport and the power deposition profile. Density control is achieved in combined heating with neutral beam injection (NBI) despite the beam particle fuelling, whereas with NBI alone a steady density rise is observed. The impact of combined heating on the impurity confinement was investigated. Electron cyclotron current drive (ECCD) was studied in different magnetic field configurations and the influence of trapped particles on the ECCD efficiency was examined experimentally and compared with theory.

The yeast TOR2 gene encodes an essential 282 kd phosphatidylinositol (PI) 3-kinase homolog. TOR2 is related to the catalytic subunit of bovine PI 3-kinase and to yeast VPS34, a vacuolar sorting protein also shown to have PI 3-kinase activity. The immunosuppressant rapamycin most likely acts by inhibiting PI kinase activity because TOR2 mutations confer resistance to rapamycin and because a TOR1 TOR2 double disruption (TOR1 is a nonessential TOR2 homolog) confers G1 arrest, as does rapamycin. Our results further suggest that 3-phosphorylated phosphoinositides, whose physiological significance has not been determined, are an important signal in cell cycle activation. In yeast, this signal may act in a signal transduction pathway similar to the interleukin-2 signal transduction pathway in T cells.

Considerable effect of the level of sustained compressive stress and Na 2 SO 4 solution attack on residual static modulus of elasticity and compressive strength was experimentally stated. The interaction effect of sulphate attack severity and the level of stress seems to be significant for the rat of concrete deterioration. Also, the character and rate of the creep-related deformations is distinctly affected by the level of stress and the severity of the attack. Besides, restraint swelling of concrete caused by sulphate attack was noted under compression.

Depth profiles of thin YBa 2 Cu 3 O 7− x films were obtained by means of secondary neutral mass spectroscopy (SNMS). It is shown that this method yields reproducible, quantitative results for the metallic composition if films with known composition are taken as reference samples. Bulk standards have proven to be unsuitable; possible reasons for this are discussed. A correlation between the SNMS data (e.g. the oxygen/oxide signals) with superconducting properties of the films could not be found. One of the main advantages of SNMS in the field of high-T c superconductors is the possibility to study diffusion processes and other reactions at the film-substrate interface. Examples for this are presented, too.

Compounds containing the 2,3-bis(trimethylstannyl)-1-alkene moiety react with aldehydes in the presence of boron trifluoride etherate to give homoallylic alcohols in which the remaining vinylic stannyl moiety has undergone halodemethylation. A mechanistic explanation for this behaviour is presented. NMR studies indicate that the addition proceeds in an erythro-selective manner.

Hexamethyl- hexaethyl- and hexabutyl-ditin add to a variety of allenes in the presence of Pd(PPh34; the reaction is reversible. Trimethylsilyltrimethyl- and tributyl-stannane also add under comparable conditions, the silyl moiety becoming attached to the central carbon atom of the allene skeleton; this reaction is, however, apparently not reversible.

While free radical hydrostannation of monosubstituted allenes with Me3SnH affords mixtures of varying composition, cyclohexylidene allene is attacked by the stannyl radical preferentially at the central carbon atom. In contrast, palladium-catalysed hydrostannation involves a regioselective attachment of the organotin moiety to the less highly substituted terminal carbon atom of the allene framework.

Fire is a major risk for the safety of NPP's. The Browns Ferry fire and other incidents have made evident that a fire might occur within all parts of a NPP. These fires may develop differently from a fire in a conventional building as usually no smoke removal systems are at hand and the fire detection and fire fighting become much more difficult than in common industrial buildings, respectively. The special “nuclear” boundary conditions e.g. the absolut confinement of radioactivity impose severe restrictions on the fire protection and fire fighting measures. Since quite a number of years serious efforts have been made to further reduce the risk of fires in NPP's e.g. by avoiding or at least minimizing any fire load, by a consequent separation of redundant systems, by additional fire insulations for components and cables, by installing automatic fire suppression systems whereever useful and possible and by improved computational predictions of the eventual fire impacts on the whole system. At the Post-SMiRT Seminar No. 6 the international and national status of work in the field of fire protection in NPP's was presented. In the present introductory part a brief discussion on risk assessment, fire incidents, fire experiments, fire modelling and future developments is being raised. In the following reports these topics are elaborated in a more extended way. Therefore one may get an international point of view about the single questons raised by studying the appropriate expert reports in the proceedings. The Seminar No. 6 is intended as to establish an international forum for experts in the field of nuclear fire safety science. It should also help the experts of fire protection to get to know the experts in nuclear engineering of different countries and further it shall contribute to an open exchange of special knowledge and experiences in safety related problems of NPP's which is an old custom already established in other fields of nuclear safety since many years.

Whereas the addition of tributyl(trimethylgermyl)stannane to 1-alkynes in the presence of tetrakis(triphenylphosphine)palladium proceeds regiospecifically, the direction of its addition to allenes is dependent on the structure of the allene.

Thin a-Si:H-films deposited by different methods have been irradiated with 20 keV-electrons. The DOS distribution or spin-density, respectively, have been investigated with various methods (CPM, SCLC, ESR). For irradiation doses between 0 and about 60 J/cm2 a linear correlation between dose and number of created defects is found, for higher doses the characteristic is increasingly sublinear. The metastability of the defects is confirmed by annealing experiments.

Zusammenfassung Bei einer thermischen Beanspruchung zementgebundener Betone laufen in der Bindemittel- und Zuschlagphase Reaktionen ab, die zu Strukturanderungen und damit verknupft zu entscheidenden Veranderungen der mechanischen Materialeigenschaften fuhren. Diese thermisch aktivierten Abbaureaktionen im Beton konnen mit Hilfe der TG und DTA nachgewiesen werden. Anhand eines “kinetischen Festigkeitsmodells” gelingt es, die Entfestigung des Materials bei einer thermischen Beanspruchung direkt mit den thermoanalytisch untersuchten Reaktionen in Beziehung zu setzen. Eine Gegenuberstellung der theoretischen Ergebnisse mit den Daten experimenteller Festigkeitsuntersuchungen zeigt trotz der vorgenommenen Vereinfachungen in weiten Temperaturbereichen eine gute Ubereinstimmung.

Summary In a rural Turkish settlement within the eumediterranean coastal belt near Antalya, soil samples were taken for determination of the seedbank and in addition to phytosociological investigations. This measure was taken to obtain more precise information about the potential species composition and the seasonal vegetation dynamics. During a period of 16 months, germination experiments have been carried out at the Institute of Ecology at the Technical University of Berlin, Berlin (West). 1714 seedlings were counted, of which 245 died unidentified. A number of 1469 (85,7 %) seedlings had been recognized and classified into 83 species. The indentified plants were classified and grouped as character-species of the Macchie and their derivates, esp. the community of overgrazed pseudo-steppic vegetation (Trift), trampling, ruderal and weed vegetation of arable fields and compared with vegetation releves of the soil sample areas. 35 species were found only in the soil samples. This resulted in a mean correspondence of 58% between seedbank and vegetation. It is being discussed why seedbank species could not be found in the vegetation, whereas others with a high cover value had no seed depositions in the soil.

The behaviour of hydrated cement paste, mortar and concrete specimens (age ∼ 110 days) was investigated at low temperatures and after cyclic temperature-time histories. The relative changes of thermal strains, compressive and tensile splitting strength as well as the alteration of pore structure were studied. The strength in the frozen state increases with decreasing temperature and rising moisture content. If the frozen water-saturated mortar or concrete is reheated to room temperature a loss of strength is registered. The loss of strength increases with the number of temperature cycles. Storing the specimens at rel. hum. below 85% no losses were registered and no irreversible expansion occured. Water-saturated mortar showed after only 12 cycles an irreversible positive strain of 2,7%, indicating internal damage which was also proved by mercury porosimetry. Thus, the moisture content seems to be one of the decisive factors affecting the sensitivity of mortar and concrete subjected to extremely low temperatures.

The specific surface and pore size distribution of normal concrete is influenced by temperature effects. Therefore, the specific surface area of concrete specimens has been computed from nitrogen adsorption isotherms after a preceding temperature treatment in a thermal balance. It was found that the specific surface area increases from 2,0 m2/g at 100°C to 4,5 m2/g at 400°C. The mean pore radius decreases from 53 A to 38 A. A temperature treatment at 665°C is connected with a further decomposition of concrete and yields a decrease of the specific surface area to 2,4 m2/g and the pore size distribution shifts to larger radii ( r = 51 A ). Due to sintering processes, at temperatures of 1000°C the porosity of the material is decisively altered and a specific surface area of 1,1 m2/g has been calculated.

Experimental investigations at temperatures up to 600 °C were made with a new concrete test equipment which allows the determination of strengths and deformations of concrete subjected to biaxial compressive stresses at high temperatures. The equipment is described and test results are reported. The test results show that the biaxial high temperature strength is greater than the uniaxial strength. An increase of the biaxial strength was observed at comparatively high temperatures. Up to 300 °C failure occurs with an explosive and spontaneous character. At higher temperatures the failure process runs moderately. The stress-strain relationships show a significant dependence on temperature and on current stress ratio: The rupture strains increase with increasing stress ratios and with increasing temperatures.

The use of made of material properties in theoretical studies may vary. It depends on the individual approach, the objective and the quality of result required. This report gives a condensed survey of the present state of knowledge in the field of high temperature properties of concrete, which may assist in giving an answer to the problem of estimating the fire behaviour of concrete members. A new materials model based on recent research results is developed and discussed. The report is divided into three different parts. Section 2 contains a brief introduction to various concrete test methods. Section 3 comprises the properties of concrete according to the existing literature and, in Section 4, a description of analytical models for the calculation of fire behaviour of concrete elements is given.

A series of reactions are described for two bifunctlonal organotin synthons, 1,2- and 2,3-bis(trimethylstannyl)-1-alkenes. These reactions include bromodemethylatlon at tin, lithiodestannylation and palladium-catalysed C-C bond formation; while the former synthon appears extremely promising as a synthetic reagent, the latter has limitations due to its tendency to decomposition.

The Jijoye EBV strain is characterized by a substitution of 1.8 kb in the C-terminal part of the EBNA 2 gene compared to B95-8 or M-ABA virus. This made it possible to construct hybridization probes specific for M-ABA (type A) and Jijoye viruses (type B), which have been used to type the EBV genomes in 38 spontaneously established cell lines. Type A is more prevalent being found in 31 of 38 cases; type B virus was found in five cell lines (Jijoye, LY 67, QIMR-GOR, BL 16, and BL 29); and two cell lines, Daudi and EB-3, contained neither the M-ABA- nor the Jijoye-specific sequences. EBV type B appears to be less ubiquitous, since all type B isolates, including AG 876 virus, originated from Central Africa, La Réunion, and New Guinea. All the other cell lines, carrying EBV type A, were established from patients from Central Africa (4), North Africa (7), New Guinea (1), and Asia (6) and from white individuals (13). The restricted geographical localization of EBV type B in parts of the southern hemisphere and its similarity to herpesvirus papio (T. Dambaugh, K. Hennessy, L. Chamnankit, and E. Kieff (1984) Proc. Natl. Acad. Sci. USA 81, 7632-7636) could suggest that such viruses may have evolved by recombination of EBV with a related Old World monkey virus, alternatively, evolution of virus variants within the human species also being conceivable.

The saturation of the creation of Staebler-Wronski-like defects in a-Si:H induced by keV-electron irradiation has been investigated in more detail. It is explained by means of a semiquantitative model basing on the breaking of a limited number of weak bonds. The results of a detailed study of the annealing behaviour at different temperatures and various damage levels are presented and are shown to be consistent with the assumption of a distribution of activation energies for the thermal healing of the metastable defects.