Bioreaktionstechnik in mikrofluidischen Reaktoren

In the last decade micro bioreactor (MBR) technology has made rapid advances in biotechnology process development and in the investigation of various biological systems from industrial to pharmaceutical biotechnology applications. MBRs range in complexity from simple micro titer‐based systems to complex automated parallel bioreactors designed to allow the meaningful scale‐up/ ‐down of conventional pilot and large‐scale bioprocesses. MBR technology and the capability to monitor cultivation process variables in situ, provide real‐time and quantitative data from the microliter cultivation. This paper gives an overview of micro technologically fabricated MBRs, for the high‐throughput operation, its design, advantages and current limitations and potential future challenges in different biotechnological fields.     

Heating and melting of wustite pellets in liquid slag

The melting behaviour of the metallized, porous wustite pellets immersed in liquid slag, as well as the influences of the metallization ratio, pre-heating temperature of the pellet and slag temperature were examined in this work by means of an X-ray imaging system. The internal structure of the pellets after having been immersed in slag was checked by optical microscope and EPMA. The adoption of digital image processing improved the image analysis dramatically and, as a result, some important phenomena, such as solid slag shell forming and melting, slag penetration, wustite component dissolution as well as the influence of experimental conditions, were quantified.     

Bubble bursting phenomenon in Gas/Metal/Slag systems

Iron droplets can be ejected into the surrounding atmosphere or entrained into the slag phase when gas bubbles pass through the metal surface or the metal/slag interface. The phenomena occurring during passage of single bubbles through the free surface and the interface were investigated by using the in-situ X-ray transmission technique. The mass of droplets ejected into the atmosphere attained a maximum value at a certain bubble size, which depended on the surface tension of the iron melt. Bubble bursting on the free surface of iron melt ejected numerous fine iron droplets called “film droplets” and a few much larger jet droplets. Two different groups of iron droplets were also observed as entrained in the slag due to bubble passage through the iron/slag interface, although the physical phenomena are to some extent different from bubble bursting to the gas phase. This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties & Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002.     

Comparison of a poly-l-lactide-co-?-caprolactone and human amniotic membrane for urothelium tissue engineering applications

The reconstructive surgery of urothelial defects, such as severe hypospadias is susceptible to complications. The major problem is the lack of suitable grafting materials. Therefore, finding alternative treatments such as reconstruction of urethra using tissue engineering is essential. The aim of this study was to compare the effects of naturally derived acellular human amniotic membrane (hAM) to synthetic poly-l-lactide-co-ε-caprolactone (PLCL) on human urothelial cell (hUC) viability, proliferation and urothelial differentiation level. The viability of cells was evaluated using live/dead staining and the proliferation was studied using WST-1 measurement. Cytokeratin (CK)7/8 and CK19 were used to confirm that the hUCs maintained their phenotype on different biomaterials. On the PLCL, the cell number significantly increased during the culturing period, in contrast to the hAM, where hUC proliferation was the weakest at 7 and 14 days. In addition, the majority of cells were viable and maintained their phenotype when cultured on PLCL and cell culture plastic, whereas on the hAM, the viability of hUCs decreased with time and the cells did not maintain their phenotype. The PLCL membranes supported the hUC proliferation significantly more than the hAM. These results revealed the significant potential of PLCL membranes in urothelial tissue engineering applications.     

The effects of vibration loading on adipose stem cell number,viability and differentiation towards bone-forming cells

Mechanical stimulation is an essential factor affecting the metabolism of bone cells and their precursors. We hypothesized that vibration loading would stimulate differentiation of human adipose stem cells (hASCs) towards bone-forming cells and simultaneously inhibit differentiation towards fat tissue. We developed a vibration-loading device that produces 3g peak acceleration at frequencies of 50 and 100 Hz to cells cultured on well plates. hASCs were cultured using either basal medium (BM), osteogenic medium (OM) or adipogenic medium (AM), and subjected to vibration loading for 3 h d^–1 for 1, 7 and 14 day. Osteogenesis, i.e. differentiation of hASCs towards bone-forming cells, was analysed using markers such as alkaline phosphatase (ALP) activity, collagen production and mineralization. Both 50 and 100 Hz vibration frequencies induced significantly increased ALP activity and collagen production of hASCs compared with the static control at 14 day in OM. A similar trend was detected for mineralization, but the increase was not statistically significant. Furthermore, vibration loading inhibited adipocyte differentiation of hASCs. Vibration did not affect cell number or viability. These findings suggest that osteogenic culture conditions amplify the stimulatory effect of vibration loading on differentiation of hASCs towards bone-forming cells.     

Bioactive glass granules: a suitable bone substitute material in the operative treatment of depressed lateral tibial plateau fractures: a prospective, randomized 1 year follow-up study

Purpose of this study was to compare bioactive glass and autogenous bone as a bone substitute material in tibial plateau fractures. We designed a prospective, randomized study consisting of 25 consecutive operatively treated patients with depressed unilateral tibial comminuted plateau fracture (AO classification 41 B2 and B3).14 patients (7 females, 7 males, mean age 57 years, range 25–82) were randomized in the bioglass group (BG) and 11 patients (6 females, 5 males, mean age 50 years, range 31–82) served as autogenous bone control group (AB). Clinical examination of the patients was performed at 3 and 12 months, patients’ subjective and functional results were evaluated at 12 months. Radiological analysis was performed preoperatively, immediately postoperatively and at 3 and 12 months. The postoperative redepression for both studied groups was 1 mm until 3 months and remained unchanged at 12 months. No differences were identified in the subjective evaluation, functional tests and clinical examination between the two groups during 1 year follow-up. We conclude that bioactive glass granules can be clinically used as filler material instead of autogenous bone in the lateral tibial plateau compression fractures.     

Characterization and differentiation of Italian Parma,San Daniele and Toscano dry-cured hams: A multi-disciplinary approach

This study aimed at characterizing the sensory quality of Italian PDO dry-cured Parma, San Daniele and Toscano hams, applying a multi-disciplinary approach. Ham sensory profile as well as physico-chemical, aromatic, morphological and textural characteristics was investigated. There was a great difference between Toscano ham and Parma and San Daniele hams, which were more similar even though differentiated. Toscano ham showed higher scores for pork-meat odor, saltiness, dryness, fibrousness and hardness; accordingly, this ham was described by a high NaCl content and by high values of instrumental hardness, cohesiveness, gumminess and chewiness. Parma ham was characterized by a cured flavor, whereas San Daniele ham showed a wider fatty area and higher pH values. Parma and San Daniele hams were also described by higher values of sweetness, RGB color values and water activity. Sensory characteristics evaluated by trained assessors were correlated to instrumental measures, indicating that instrumental devices can be effectively applied for dry-cured ham characterization.     

Characterization of Er in Porous Si

ABSTRACT: The fabrication of porous Si-based Er-doped light emitting devices is a very promising developing field for all-silicon light emitters. However, while luminescence of Er-doped porous silicon devices has been demonstrated, very little attention has been devoted to the doping process itself. We have undertaken a detailed study of this process examining the porous silicon matrix from several points of view, during and after the doping. In particular, we have found that the Er doping process shows a threshold level which, as evidenced by the cross correlation of the various techniques used, does depend on the sample thickness and on the doping parameters.