Design of novel materials for additive manufacturing - Isotropic microstructure and high defect tolerance.

Electron Beam Melting (EBM) is a powder-bed additive manufacturing technology enabling the production of complex metallic parts with generally good mechanical properties. However, the performance of powder-bed based additively manufactured materials is governed by multiple factors that are difficult to control. Alloys that solidify in cubic crystal structures are usually affected by strong anisotropy due to the formation of columnar grains of preferred orientation. Moreover, processing induced defects and porosity detrimentally influence static and cyclic mechanical properties. The current study presents results on processing of a metastable austenitic CrMnNi steel by EBM. Due to multiple phase transformations induced by intrinsic heat-treatment in the layer-wise EBM process the material develops a fine-grained microstructure almost without a preferred crystallographic grain orientation. The deformation-induced phase transformation yields high damage tolerance and, thus, excellent mechanical properties less sensitive to process-induced inhomogeneities. Various scan strategies were applied to evaluate the width of an appropriate process window in terms of microstructure evolution, porosity and change of chemical composition.

Application of in situ thermography for evaluating the high-cycle and very high-cycle fatigue behaviour of cast aluminium alloy AlSi7Mg (T6).

The present paper illustrates the application of infrared thermal measurements for the investigation of crack initiation point and crack propagation in the high-cycle and the very high-cycle fatigue range of cast AlSi7Mg alloy (A356). The influence of casting defects, their location, size and amount was studied both by fractography and thermography. Besides internal and surface fatigue crack initiation as a further crack initiation type multiple fatigue crack initiation was observed via in situ thermography which can be well correlated with the results from fractography obtained by SEM investigations. In addition, crack propagation was studied by the development of the temperature measured via thermography. Moreover, the frequency influence on high-cycle fatigue behaviour was investigated. The presented results demonstrate well that the combination of fractography and thermography can give a significant contribution to the knowledge of crack initiation and propagation in the VHCF regime.

[Preventable mistakes during endotracheal intubation. Overview and concepts]. / Vermeidbare Fehler bei der Intubation. Überblick und Konzepte.

Endotracheal intubation is a standard procedure in anesthesiology as well as in intensive care medicine in many forms of assisted spontaneous breathing or controlled ventilation. In addition it continues to be the gold standard for airway protection in prehospital and in-hospital emergency medicine settings. Approaches will have to be considered to help prevent errors before they occur not only in the non-elective use of endotracheal intubation. The most common preventable situations are summarized in this paper.

Practical skills training influences knowledge and attitude of dental students towards emergency medical care.

BACKGROUND: Medical emergencies in dental practice are generally perceived as being rare. Nonetheless, recent studies have shown that incidents occur on a regular basis. Therefore, patients have the right to expect necessary skills to manage life-threatening situations from every dentist. OBJECTIVE: To observe students' attitude and self-assessment towards emergency medical care (EMC) and its practical appliance. MATERIAL AND METHODS: Students of dentistry took part in small group sessions for adult and paediatric basic life support. Participants filled out pre-post questionnaires regarding knowledge and attitude towards EMC (6, respectively, 10-point Likert scale). Additionally, feedback was asked for the quality of course and tutors. RESULTS: Forty dental students in their last 2 years of study registered for the EMC courses. The majority had never attended any first-aid course; the mean age was 25% and 75% were women. A comparison between pre- and post-evaluation showed that the participation in practical training easily enhances the students' awareness of EMC importance as well as self-confidence in managing emergencies. After the course, 71% shared the opinion that retraining should be obligatory for all medical personnel. At the same time, students' self-assessment of confidence for specific tasks got significant upgrades in every aspect. CONCLUSION: The evaluation data clearly show the participants' needs to deal with topics of EMC within the curriculum of dentistry. The proposed course is able to change participants' attitudes towards EMC and its importance for their daily practice. The considerable enhancement of self-confidence in performing EMC-techniques might also lead to more willingness to manage emergency situations.

Murine leukocytes with ring-shaped nuclei include granulocytes, monocytes, and their precursors.

Leukocytes with ring-shaped nuclei (ring cells) are present in bone marrow (BM; approximately 50% of BM cells), in peripheral blood (PB), and in inflammatory infiltrates of mice, but also in humans during myeloproliferative disorders. They are usually referred to as polymorphonuclear cells (PMN), but we demonstrate that they additionally encompass different types of mononuclear (MNC)-like ring cells. PMN ring cells had constricted ring-shaped nuclei with a wide cytoplasmic center and were sorted among the GR-1high fraction. The MNC-like ring cells belonged to the GR-1low fraction. Their nuclei were not segmented and the cytoplasmic center of their nuclei was small. They were heterogeneous with one subgroup containing monocytes/macrophages according to ultrastructure, immunophenotype (BM8, F4/80, CD13, ER-HR3), activity of unspecific esterase, and phagocytosis of Leishmania major. A second subgroup contained myeloic precursor cells as they proliferated (Ki67), expressed ER-MP12, and showed on ultrastructure distribution patterns of peroxidase activity compatible with myelocytes, promyelocytes, or promonocytes. A third subgroup of cells had large, sometimes lobulated nuclei, was lineage marker(negative/low) (GR-1, Mac-1, B220 etc.), CD38-, but c-kit+ and sca-1+, and thus belonged to a close progeny of murine hematopoietic stem cells. In PB, ring cells encompassed mainly PMN, but also monocytes and cells with characteristics of both the granulocytic and monocytic lineage. Thus, ring cells comprise mature and precursor forms of myeloic cells. Their analysis revealed that in mice a clear distinction between the granulocytic and monocytic lineage beyond the GM-CFU stage is not always feasible.

Expression of fetal cytokeratins in epidermal cells and colloid bodies in lichen planus.

Clusters of immunoglobulin (Ig)-coated colloid bodies (CBs) in the dermo-epidermal zone are a typical immunohistochemical feature in lichen planus (LP)-lesions. They are considered to represent dyskeratotic basal keratinocytes, yet their composition has not been completely elucidated. In the present study, skin biopsies of 10 LP-lesions, 3 other dermatoses, and 10 biopsies of normal skin were studied immunohistochemically using monoclonal antibodies (MAbs) against fetal and differentiated epidermal antigens. CBs were identified by FITC-anti-Ig. Binding of MAb was visualized by double staining technique. Cytokeratin (CK) 10/11, a marker of epidermal differentiation, was consistently detected in suprabasal keratinocytes and also in up to 95% of Ig-positive CBs in LP. CK10/11 was additionally detected in basal keratinocytes in 9 LP-lesions, but not in normal skin. The basal cell-specific MAb BL7 stained basal layer keratinocytes in all biopsies. In contrast to normal skin, in LP scattered suprabasal keratinocytes and CBs were also positive for BL7 in 10 and 7 cases, respectively. While fetal cytokeratins (CK13 and CK8/18) were completely absent in control skin specimens, both cytokeratins were detected in various numbers of keratinocytes and CBs in all LP-lesions. Our results support the hypothesis of an epidermal origin of CBs. The cytokeratin profile seems to be severely disturbed in LP. This includes both accelerated differentiation by the expression of suprabasal CK10/11 in basal keratinocytes and dedifferentiation by the expression of fetal epidermal antigens (CK13 and CK8/18). It is tempting to speculate that the observed alterations may trigger T-cell activation and inflammatory onset in LP.

[Gram-positive septic-toxic shock with bullae. Intraepidermal splitting as an indication of toxin effect]. / Grampositiver septisch-toxischer Schock mit Blasenbildung. Die intraepidermale Spaltbildung als Hinweis für die Toxineinwirkung.

A fourteen-year-old girl with acute otitis media died from gram positive sepsis and toxic shock despite intensive treatment. The definitive bacteriological results showed positive cultures for both S. aureus and S. pyogenes serotype A. In vitro the bacteria produced the bacterial superantigens TSST-1, enterotoxin A, enterotoxin C (S. aureus) and erythrogenic toxin C (S. pyogenes). The patient presented with large flaccid sterile bullae on her chest and arms as well as necrotizing fasciitis. Tzanck test showed keratinozytes without necrosis and no inflammatory cells. Frozen-section and conventional skin biopsy specimens revealed subcorneal intraepidermal cleavage. These cytological and histological findings are those of staphylococcal scalded skin syndrome (SSSS) and differ from bullous erysipelas or toxic epidermal necrolysis (TEN). Therefore bacterial exotoxins are most likely responsible for the intraepidermal blistering in our case just as in SSSS. Bullae are an unfavorable prognostic sign in gram positive toxic shock syndrome. Both Tzanck test and frozen-section biopsy are easy to perform and useful in the early and rapid recognition of gram positive bullous toxic shock syndrome.

Immunological reactions against PMMA lens material?

We investigated the kind of reactions that occur after injection of a PMMA lens powder into the back skin of rabbit. The lens powder was suspended in NaCl and incomplete Freund's adjuvant to reinforce the immunological reaction. The ELISA test was carried out to detect antibodies against the lens material as a whole and against the UV absorber Tinuvin in particular. We also performed histological and immunohistochemical examinations of the back skin. We did not detect antibodies against either the lens material or against Tinuvin. Histological examination showed a foreign-body or delayed allergic reaction against the lens material. Lymphocytes surrounding the PMMA were found to be mainly of the T-type, which supports the results of the ELISA test.

[Corneal sensibility following epikeratophakia]. / Zur Hornhautsensibilität nach Epikeratophakie.

The postoperative rate of reinnervation following corneal surgery is widely considered to be a useful indicator of the healing process. This study reports the corneal sensitivity of 14 patients following epikeratophakia for different indications (myopia, aphakia and keratoconus) after time periods ranging from 7 to 104 weeks. All transplants were clear at the time of measurement. A newly developed aesthesiometer (using a low electric current for stimulation) was employed. Nine positions on the operated eye were chosen for the measurements, five locations of the non-operated fellow eye served as controls. On the operated eye the corneal sensitivity peripheral to the trephination were significantly reduced at the 9 and 12 o'clock positions as compared to the other eye. The 3 and 6 o'clock locations showed no significant difference. On the epikeratophakia lenticule the sensitivity was significantly reduced at all points, the center showing the largest difference (p less than 0.001). No correlation with age, sex or the indication for the procedure was observed. Although there was a trend of a positive correlation between the postoperative time period and the central corneal sensitivity, the follow-up was too short to reach significant levels. The nearly complete lack of corneal sensitivity, particularly in the center of the transplant is therefore well compatible with its long-time survival, even when the lenticule has been prepared with the cryolathe and lyophilized for transportation.

[Comparative studies of preventive antibiotic administration in ERCP]. / Vergleichende Untersuchungen zur Antibiotikaprophylaxe bei der ERCP.

In a nonblind nonrandomized clinical trial two groups of patients who were undergoing ERCP - A (n = 182) with antibiotic prophylaxis and B (n = 220) without an antibiotic--were compared on a prospective basis. The efficacy of properly timed prophylaxis with a therapeutically effective antibiotic had previously been established by a pilot study and a definitive trial based on HPLC assays of endoscopic biopsy specimens taken from the duodenal papilla. In Group A (n = 182) there was hyperamylasaemia without a leucocytic reaction in only 18 (14.75%) of the ERP patients and two (3.33%) of the ERC patients, but in Group B (no antibiotic - n = 220) this change was detected in 48 (35.29%) of the ERP patients and 12 (14.28%) of the ERC patients (P = 0.00018 and 0.043 respectively). Hyperamylasaemia with a leucocytic reaction occurred in only one patient with ERP from Group A (0.82%) as compared with 15 patients (11.02%) from the untreated group (P = 0.00047). These results were highly significant. There were three cases of subclinical pancreatitis and two of acute pancreatitis--all of them in the control group. Although these results were not statistically significant (because the number of cases was too small), they are clearly consistent with the growing tendency towards using antibiotic cover. On the basis of these results we regard antibiotic prophylaxis during ERCP as a sensible precaution, and in patients with any concurrent disease which heightens the risk it is essential.

[Measuring electrical impedance in normal and pathologic corneas]. / Messung der elektrischen Impedanz an normalen und pathologischen Hornhäuten.

With a new technique the impedance of 89 normal and 7 severely damaged corneas was determined in vivo to look into the correlation between impedance and corneal cell damage. We found highly significant differences in impedance between normal and pathologically altered corneas. At 500 Hz frequency the impedance of normal corneas was 53.6 kOhm while the impedance of burned corneas only averaged 8.0 kOhm. There seems to be a correlation between the degree of pathological alteration of the corneal tissue and impedance as measured with this technique. The electrode head used allows fast, reproducible measurement of corneal impedance without any strain on the patient. Further studies must elucidate whether the method can be used as an early indicator of corneal damage before the onset of macroscopic change.

The contributions made by multinational enterprises to the economic development and political stabilization of less developed countries seen in its dependence on the world economic order.

PIP: For their own advantage, developing countries should attempt to extend and not to limit liberalication directed at improving competition. Particularly, developing countries should argue that the private export of capital, which is combined with the transfer of growth-promoting technology, should be increased rather than restricted and the security of private ownership should also be increased. A scheme insuring property rights should be established, whereby the amounts contributed would be fixed according to the political stability of the country concerned. Some thoughts are presented on the basic principles of the world economy and on the way in which the world economic order should be shaped. On the basis of this plan, the world economy is understood as a system of varying developed regions. Attention is focused on the basic principle of the world economic order, suggestions for a new world economic order, the concept of a functional world economic order, starting points and goals of an economic policy orientated towards development, instruments of a national structural policy orientated by the world economy -- cooperative association and/or multinational firms, and demands made upon single economic orders and upon the system of their cooperation.^ieng