Manufacture of chitosan microbeads using centrifugally driven flow of gel-forming solutions through a polymeric micronozzle

A centrifugally driven pulse-free flow has been used for generation of tripolyphosphate (TPP)-gelated chitosan beads with tunable diameters ranging from 148 to 257 lm. The production process requires a single motor as the sole actively actuated component. The 2% (w/w) chitosan solution was extruded through a polymeric nozzle with an inner diameter of 127 lm in the centrifugal field ranging from 93 to 452g and the drops were collected in an Eppendorf tube containing 10% (w/w) TPP solution at pH 4.0. The reproducibility of the bead diameters out of different nozzles was very good with overall CVs of the bead diameters down to 15% and the production rate was 45 beads per second per nozzle at 44 Hz rotor frequency. The production rate was proportional to the sixth power of the rotor frequency, which was explained by the non-Newtonian behaviour of the chitosan solution with a flow behaviour index of 0.466. An analytical model for the bead diameter and production rate has been presented and validated by the experimental data. The shrinkage of chitosan drops during gelation was estimated from the observations and the theoretical model

Roadmap on Label-Free Super-resolution Imaging

Label-free super-resolution (LFSR) imaging relies on light-scattering processes in nanoscale objects without a need for fluorescent (FL) staining required in super-resolved FL microscopy. The objectives of this Roadmap are to present a comprehensive vision of the developments, the state-of-the-art in this field, and to discuss the resolution boundaries and hurdles that need to be overcome to break the classical diffraction limit of the label-free imaging. The scope of this Roadmap spans from the advanced interference detection techniques, where the diffraction-limited lateral resolution is combined with unsurpassed axial and temporal resolution, to techniques with true lateral super-resolution capability that are based on understanding resolution as an information science problem, on using novel structured illumination, near-field scanning, and nonlinear optics approaches, and on designing superlenses based on nanoplasmonics, metamaterials, transformation optics, and microsphere-assisted approaches. To this end, this Roadmap brings under the same umbrella researchers from the physics and biomedical optics communities in which such studies have often been developing separately. The ultimate intent of this paper is to create a vision for the current and future developments of LFSR imaging based on its physical mechanisms and to create a great opening for the series of articles in this field.Peer reviewe

Centrifugal extraction of plasma from whole blood on a rotating disk

We present a centrifugal process for the extraction of plasma from sediment by a decanting structure, terminating with metered plasma which is readily available for subsequent on-disk processing. Our technique supplies 2 ml plasma from 5 ml of whole blood at moderate spinning frequencies of 40 Hz within 20 s, only. The residual cell concentration in the purified plasma amounts to less than 0.11%, independent of the frequency of rotation. A capillary duct connects the extracted plasma to subsequent on-disk processing units

Manufacture of chitosan microbeads using centrifugally driven flow of gel-forming solutions through a polymeric micronozzle

A centrifugally driven pulse-free flow has been used for generation of tripolyphosphate (TPP)-gelated chitosan beads with tunable diameters ranging from 148 to 257 pm. The production process requires a single motor as the sole actively actuated component. The 2% (w/w) chitosan solution was extruded through a polymeric nozzle with an inner diameter of 127 mu m in the centrifugal field ranging from 93 to 452g and the drops were collected in an Eppendorf tube containing 10% (w/w) TPP Solution at pH 4.0. The reproducibility of the bead diameters out of different nozzles was very good with overall CVs of the bead diameters down to 15% and the production rate was 45 beads per second per nozzle at 44 Hz rotor frequency. The production rate was proportional to the sixth power of the rotor frequency, which was explained by the non-Newtonian behaviour of the chitosan solution with a flow behaviour index of 0.466. An analytical model for the bead diameter and production rate has been presented and validated by the experimental data. The shrinkage of chitosan drops during gelation was estimated from the observations and the theoretical model. (C) 2009 Elsevier Inc. All rights reserve

Three-dimensional printing creates models for surgical planning of aortic valve replacement after previous coronary bypass grafting.

PURPOSE Resternotomy for aortic valve replacement in patients with previous coronary artery bypass grafting and an internal mammary artery graft may be a surgical problem. Thus, we are exploring the effect of using rapid prototyping techniques for surgical planning and intraoperative orientation during aortic valve replacement after previous coronary artery bypass grafting (CABG). DESCRIPTION As a proof of concept, we studied a patient who had undergone CABG 5 years earlier. At that time the patient received a left internal mammary artery graft to the left anterior descending artery and a venous graft to the right coronary artery. Now the patient required aortic valve replacement due to symptomatic aortic valve stenosis. The left internal mammary artery bypass and the right coronary artery bypass were patent and showed good flow in the angiography. The patient was examined by 128-slice computed tomography. The image data were visualized and reconstructed. Afterwards, a replica showing the anatomic structures was fabricated using a rapid prototyping machine. EVALUATION Using data derived from 128-slice computed tomography angiography linked to proprietary software, we were able to create three-dimensional reconstructions of the vascular anatomy after the previous CABG. The models were sterilized and taken to the operating theatre for orientation during the surgical procedure. CONCLUSIONS Stereolithographic replicas are helpful for choosing treatment strategies in surgical planning and for intraoperative orientation during reoperations of patients with previous CABG

Breast cancer risk assessment in a mammography screening program and participation in the IBIS-II chemoprevention trial

International audienceIt has been shown in several studies that antihormonal compounds can offer effective prophylactic treatment to prevent breast cancer. In view of the low participation rates in chemoprevention trials, the purpose of this study was to identify the characteristics of women taking part in a population-based mammography screening program who wished to obtain information about the risk of breast cancer and then participate in the the International Breast Cancer Intervention Study II (IBIS-II) trial, a randomized double-blind controlled chemoprevention trial comparing anastrozole with placebo. A paper-based survey was conducted in a population-based mammography screening program in Germany between 2007 and 2009. All women who met the criteria for the mammography screening program were invited to complete a questionnaire. A total of 2,524 women completed the questionnaire, and 17.7% ( = 446) met the eligibility criteria for the IBIS-II trial after risk assessment. The women who wished to receive further information about chemoprevention were significantly younger ( < 0.01) and had significantly more children ( = 0.03) and significantly more relatives with breast cancer ( < 0.001). There were no significant differences between the participants with regard to body mass index or hormone replacement therapy. Normal mammographic findings at screening were the main reason (42%) for declining to participate in the IBIS-II trial or attend risk counseling. The ultimate rate of recruitment to the IBIS-II trial was very low (three women). Offering chemoprevention to women within a mammography screening unit as part of a paper-based survey resulted in low participation rates for both, the survey and the final participation in the IBIS-II trial. More individualized approaches and communication of breast cancer risk at the time of the risk assessment might be helpful to increase the participation and the understanding of chemopreventive approaches