Biolithography : selective joining using antibody-antigen reactions

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.Includes bibliographical references (p. 211-212).Biolithography is a contribution to the field of Solid Free Form Fabrication. Part production is based on selective joining using antibody- antigen reactions, where the selectively is based on the thermal sensitivity of such proteins. Antibodies and antigens can be chemically immobilized to a variety of substrate materials: polymeric, ceramic and metallic. In the present investigation, antibody coated 1 [mu]m polystyrene beads and antigen coated glass surface substrates, as well as, antigen solutions were used. Both antibodies and antigens were multivalent i.e. have more that one binding site for each other; thus, two antibody coated beads could be held together by one antigen. Selective deposition was demonstrated by thermally deactivating antigen coated onto glass and precipitating antibody coated beads. Bead deposition was selective to the regions of remaining active antigens; thus, revealing the defined deactivated region. Thermal deactivation of the antigen coated substrate was first demonstrated with a 90°C water jet and improved using an argon ion laser which produced line widths on the order of tens of microns. Selective definition of geometry was an extension of the coating process precipitating not one but two bead layers and linking beads using antigen in solution. The thermal deactivation mechanism was a modified 90°C water jet that had line width resolution on the order of millimeters. Line definition was on both antigen coated bases and bound bead bases; thus, thermal deactivation was effective on both immobilized antigen (glass) and antibody (bead). The selective deposition of antibody coated substrate was demonstrated by thermally deactivating immobilized antigens and antibodies on surface substrates. Definition resolution was dependent on the thermal deactivation mechanism used.by Gail Marilyn Thornton.S.M

Enhanced capability in a gas aggregation source for magnetic nanoparticles

We describe the characterization of a high-temperature (2000 K) thermal gas aggregation source that is ultrahigh vacuum compatible and can cleanly deposit transition metal clusters with partial pressures of contaminants in the 10(-11) mbar range allowing codeposition with highly reactive matrices. In particular, we investigate the effect of varying (i) the bath gas pressure and composition on the size distribution and flux of clusters produced and (ii) the position of the crucible within the source. The mass spectra of Fe clusters produced, recorded using a quadrupole filter, show that changing the operating conditions and configuration of the source allow a wide range of cluster sizes-3000-320 000 amu (similar to 50-6000 atoms for Fe or Co) to be produced. We demonstrate the cleanliness of the source by producing uncontaminated Fe clusters in rare-earth matrices

MACiE (Mechanism, Annotation and Classification in Enzymes): novel tools for searching catalytic mechanisms

MACiE (Mechanism, Annotation and Classification in Enzymes) is a database of enzyme reaction mechanisms, and is publicly available as a web-based data resource. This paper presents the first release of a web-based search tool to explore enzyme reaction mechanisms in MACiE. We also present Version 2 of MACiE, which doubles the dataset available (from Version 1). MACiE can be accessed fro

What are the sources of stress and distress for general practitioners working in England? A qualitative study

OBJECTIVES: This paper reports the sources of stress and distress experienced by general practitioners (GP) as part of a wider study exploring the barriers and facilitators to help-seeking for mental illness and burnout among this medical population. DESIGN: Qualitative study using in-depth interviews with 47 GP participants. The interviews were audio-recorded, transcribed, anonymised and imported into NVivo V.11 to facilitate data management. Data were analysed using a thematic analysis employing the constant comparative method. SETTING: England. PARTICIPANTS: A purposive sample of GP participants who self-identified as: (1) currently living with mental distress, (2) returning to work following treatment, (3) off sick or retired early as a result of mental distress or (4) without experience of mental distress. Interviews were conducted face-to-face or over the telephone. RESULTS: The key sources of stress/distress related to: (1) emotion work-the work invested and required in managing and responding to the psychosocial component of GPs' work, and dealing with abusive or confrontational patients; (2) practice culture-practice dynamics and collegial conflict, bullying, isolation and lack of support; (3) work role and demands-fear of making mistakes, complaints and inquests, revalidation, appraisal, inspections and financial worries. CONCLUSION: In addition to addressing escalating workloads through the provision of increased resources, addressing unhealthy practice cultures is paramount. Collegial support, a willingness to talk about vulnerability and illness, and having open channels of communication enable GPs to feel less isolated and better able to cope with the emotional and clinical demands of their work. Doctors, including GPs, are not invulnerable to the clinical and emotional demands of their work nor the effects of divisive work cultures-culture change and access to informal and formal support is therefore crucial in enabling GPs to do their job effectively and to stay well

Did the evidence-based intervention (EBI) programme reduce inappropriate procedures, lessen unwarranted variation or lead to spill-over effects in the National Health Service?

Background Health systems are under pressure to maintain services within limited resources. The Evidence-Based Interventions (EBI) programme published a first list of guidelines in 2019, which aimed to reduce inappropriate use of interventions within the NHS in England, reducing potential harm and optimising the use of limited resources. Seventeen procedures were selected in the first round, published in April 2019. Methods We evaluated changes in the trends for each procedure after its inclusion in the EBI’s first list of guidelines using interrupted time series analysis. We explored whether there was any evidence of spill-over effects onto related or substitute procedures, as well as exploring changes in geographical variation following the publication of national guidance. Results Most procedures were experiencing downward trends in the years prior to the launch of EBI. We found no evidence of a trend change in any of the 17 procedures following the introduction of the guidance. No evidence of spill-over increases in substitute or related procedures was found. Geographic variation in the number of procedures performed across English CCGs remained at similar levels before and after EBI. Conclusions The EBI programme had little success in its aim to further reduce the use of the 17 procedures it deemed inappropriate in all or certain circumstances. Most procedure rates were already decreasing before EBI and all continued with a similar trend afterwards. Geographical variation in the number of procedures remained at a similar level post EBI. De-adoption of inappropriate care is essential in maintaining health systems across the world. However, further research is needed to explore context specific enablers and barriers to effective identification and de-adoption of such inappropriate health care to support future de-adoption endeavours

Did the evidence-based intervention (EBI) programme reduce inappropriate procedures, lessen unwarranted variation or lead to spill-over effects in the National Health Service?

Background: Health systems are under pressure to maintain services within limited resources. The Evidence-Based Interventions (EBI) programme published a first list of guidelines in 2019, which aimed to reduce inappropriate use of interventions within the NHS in England, reducing potential harm and optimising the use of limited resources. Seventeen procedures were selected in the first round, published in April 2019. Methods: We evaluated changes in the trends for each procedure after its inclusion in the EBI’s first list of guidelines using interrupted time series analysis. We explored whether there was any evidence of spill-over effects onto related or substitute procedures, as well as exploring changes in geographical variation following the publication of national guidance. Results: Most procedures were experiencing downward trends in the years prior to the launch of EBI. We found no evidence of a trend change in any of the 17 procedures following the introduction of the guidance. No evidence of spill-over increases in substitute or related procedures was found. Geographic variation in the number of procedures performed across English CCGs remained at similar levels before and after EBI. Conclusions: The EBI programme had little success in its aim to further reduce the use of the 17 procedures it deemed inappropriate in all or certain circumstances. Most procedure rates were already decreasing before EBI and all continued with a similar trend afterwards. Geographical variation in the number of procedures remained at a similar level post EBI. De-adoption of inappropriate care is essential in maintaining health systems across the world. However, further research is needed to explore context specific enablers and barriers to effective identification and de-adoption of such inappropriate health care to support future de-adoption endeavours