Bücher

Ohne Zusammenfassung VDI     

Experimental and calculated liquid-liquid interfacial tension in demixing metal alloys

Liquid-liquid interracial tension in binary and temary Al-based monotectic systems has been determined experimentally with a tensiometric method in a wide temperature interval. The temperature dependence of the interfacial tension is well described by a power law function of the type σαβ - （1 - T/Tc）δ with the critical exponent δ= 1.3 and a critical temperature Tc. Theoretical models describing the liquid-liquid interface in monotectic alloys and their applicability for calculation of the interfacial tension and its temperature dependence in binary systems are considered.     

Modification of Iron with Degradable Silver Phases Processed via Laser Beam Melting for Implants with Adapted Degradation Rate

In medical technology, implants are used to improve the quality of patients’ lives. The development of materials with adapted properties can further increase the benefit of implants. If implants are only needed temporarily, biodegradable materials are beneficial. In this context, iron-based materials are promising due to their biocompatibility and mechanical properties, but the degradation rate needs to be accelerated. Apart from alloying, the creation of noble phases to cause anodic dissolution of the iron-based matrix is promising. Due to its high electrochemical potential, immiscibility with iron, biocompatibility, and antibacterial properties, silver is suited for the creation of such phases. A suitable technology for processing immiscible material combinations is powder-bed-based procedure like laser beam melting. This procedure offers short exposure times to high temperatures and therefore a limited time for diffusion of alloying elements. As the silver phases remain after the dissolution of the iron matrix, a modification is needed to ensure their degradability. Following this strategy, pure iron with 5 wt% of a degradable silver–calcium–lanthanum alloy is processed via laser beam melting. Investigation of the microstructure yields achievement of the intended microstructure and long-term degradation tests indicates an impact on the degradation, but no increased degradation rate.     

Equivalence of some common linear feature extraction techniques for appearance-based object recognition tasks

Recently, a number of empirical studies have compared the performance of PCA and ICA as feature extraction methods in appearance-based object recognition systems, with mixed and seemingly contradictory results. In this paper, we briefly describe the connection between the two methods and argue that whitened PCA may yield identical results to ICA in some cases. Furthermore, we describe the specific situations in which ICA might significantly improve on PCA     

Autonomic information flow improves prognostic impact of task force HRV monitoring

Heart rate variability (HRV) represents the cardiovascular control mediated by the autonomic nervous system and other mechanisms. In the established task force HRV monitoring different cardiovascular control mechanisms can approximately be identified at typical frequencies of heart rate oscillations by power spectral analysis. HRV measures assessing complex and fractal behavior partly improved clinical risk stratification. However, their relationship to (patho-)physiology is not sufficiently explored. Objective of the present work is the introduction of complexity measures of different physiologically relevant time scales. This is achieved by a new concept of the autonomic information flow (AIF) analysis which was designed according to task force HRV. First applications show that different time scales of AIF improve the risk stratification of patients with multiple organ dysfunction syndrome and cardiac arrest patients in comparison to standard HRV. Each group's significant time scales correspond to their respective pathomechanisms.     

Regional Anticoagulation with Sodium Citrate in Pediatric Patients on Intermittent Hemodialysis Therapy with Bleeding Risks

Heparin‐free anticoagulation in hemodialysis (HD) is advocated for patients with clotting abnormalities and risk of bleeding. Objective: First publication on regional citrate anticoagulation (RCA) in children. RCA is free from systemic effects, guarantees excellent dialyzer life, but requires careful monitoring. Methods: We report on 3 patients treated by intermittent RCA HD (4 h each, high‐flux dialyzer F40, Fresenius): (1) 17‐year‐old boy (renal transplant failure, access via cubital Cimino fistula) after hypertensive intra‐cerebral hemorrhage (2 sessions); (2) 13‐year‐old girl (hemolytic uremic syndrome, access via jugular vein Shaldon catheter) after abdominal surgery and bleeding (8 sessions); and (3) 7‐year‐old boy (hyperoxaluria, access via PermCath^® jugular vein catheter) after renal transplant biopsy (3 sessions). Sodium citrate 30% was infused into the extra corporeal circuit (blood flow 150 mL/min) before dialyzer (initial flow 30 mL/min) and calcium gluconate 10% for antidote into venous line near of catheter or fistula (initial flow 40 mL/min). Post‐dialyzer extracorporeal serum Ca⁺⁺ (aim < 0.3 mmol/L) and pre‐dialyzer intra‐corporeal Ca⁺⁺ (aim > 0.9) were measured for every 30 min. Serum Na⁺, K⁺, base excess (BE), blood flow, blood pressure, heart rate, and blood out‐flow and in‐flow pressure were also monitored. Results: For adequate RCA (mean extracorporeal serum Ca⁺⁺ 0.24 ± 0.04 mmol/L), a mean citrate flow of 36.1 ± 5.9 mL/h and a mean calcium substitution rate of 40.8 ± 3.4 mL/h were needed. Intra‐corporeal Ca⁺⁺ was kept at 1.10 ± 0.07 mmol/L. Extracorporeal activated clotting time (ACT) was 194 ± 41 and intra‐corporeal ACT 90 ± 12 sec. Serum Na⁺, K⁺, and BE during HD were 138 ± 2, 3.5 ± 0.3, and ?0.6 ± 1.1 mmol/L, respectively. Mean arterial blood pressures of patients 1–3 were 117 ± 5, 103 ± 5, and 102 ± 6 mmHg. All patients were stable and without any bleeding during HD. The only adverse event was 1 episode of hypocalcemia (Ca⁺⁺ < 0.6 mmol/L) cured by stopping dialysis. Conclusions: Local anticoagulation with sodium citrate during intermittent HD can be applied safely in children and adolescents.     

Chemikalienfreie Bekämpfung von Holzschädlingen durch dielektrische Erwärmung mit Radiowellen und Mikrowellen

Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase.     

Stocking wild adult Florida largemouth bass (Micropterus salmoides floridanus): An additional fish management tool

Stocking of largemouth bass is an important management tool for fish management. The stocking of hatchery‐produced fingerling or advanced‐fingerling bass to supplement bass year‐classes, however, has exhibited varying success. Utilizing a different approach, a multiyear stocking programme using wild adult largemouth bass was initiated at the Harris Chain of Lakes (3800 ha Lake Griffin; 1811 ha Lake Dora) in central Florida. Wild adult bass (24 781 fish), ranging in size from 200 mm total length (TL) to over 600 mm TL, were stocked in Lake Griffin (13 932 fish) and Lake Dora (10 849 fish). One month after stocking, the number of stocked bass caught in electrofishing catches in Lake Griffin and Lake Dora was ~10% and 22%, respectively. Estimates of mortality were similar to the native largemouth bass, although the movement of stocked fish into other connecting water bodies was extensive. For the Lake Griffin/Lake Dora stocking programme, bass were transferred at a cost of $10.09–19.89 per fish, depending on how the costs of the project are calculated ($250 000 for just the capture and transport of the fish vs. $492 775 for the total project). Considering only capture and transport costs, conservative benefit/cost ratio estimates would be $1.77/$1.00 spent for replacement and $1.85/$1.00 spent recreational costs, although the benefit/cost ratios could exceed $10/$1. Based on the present study, stocking wild adult largemouth bass is a cost‐effective tool for managing largemouth bass.