How aerogel additives can significantly improve the casting process in foundry applications

Cavities in castings of metals and alloys are obtained by so-called cores, which are made of polymeric-bonded sands. Special additives are used to overcome negative effects that cause a lot of casting defects. Organic resorcinol-formaldehyde (RF) or inorganic carbon aerogel in granular form can replace conventional additives without any effort in the foundry process and offer a variety of advantages due to their nanostructure and composition. We established a synthesis of these aerogel additives for iron casting, transferring the production from laboratory to pilot plant scale, elevating the level of development with respect to foundry needs. Our approach yields about 15 kilogram of RF aerogel in one batch. Further processing includes coarse milling, screening and carbonization of the organic aerogel to amorphous, nanostructured, highly porous carbon with special features. Practical applicability of the additives has been tested and examined in a demanding case of iron casting. We were able to identify some very positive effects of the aerogel additive to the casting process compared to the regular used additive: higher core strength, delayed evolution of gas due to decomposition of the binder, significant reduction of gas emissions (BTXE, phenol, formaldehyde), smooth surface. Additionally, the results show, that a considerable improvement of energy efficiency at different stages of the foundry process can be achieved by the application of aerogel additives

Direct measurements of the extraordinary optical momentum and transverse spin-dependent force using a nano-cantilever

Known since Kepler's observation that a comet's tail is oriented away from the sun, radiation pressure stimulated remarkable discoveries in electromagnetism, quantum physics and relativity [1,2]. This phenomenon plays a crucial role in a variety of systems, from atomic [3-5] to astronomical [6] scales. The pressure of light is associated with the momentum of photons, and it is usually assumed that both the optical momentum and the radiation-pressure force are naturally aligned with the propagation of light, i.e., its wavevector. Here we report the direct observation of an extraordinary optical momentum and force directed perpendicular to the wavevector, and proportional to the optical spin (i.e., degree of circular polarization). Such optical force was recently predicted for evanescent waves [7] and other structured fields [8]. It can be associated with the enigmatic "spin-momentum" part of the Poynting vector, which was introduced by Belinfante in field theory 75 years ago [9-11]. We measure this unusual transverse momentum using a nano-cantilever capable of femto-Newton resolution, which is immersed in an evanescent optical field above the total-internal-reflecting glass surface. Furthermore, the transverse force we measure exhibits another polarization-dependent contribution determined by the imaginary part of the complex Poynting vector. By revealing new types of optical forces in structured fields, our experimental findings revisit fundamental momentum properties of light and bring a new twist to optomechanics.Comment: 9 pages, 3 figures, Supplementary Informatio

Comparing PTSD symptom networks in type I vs. type II trauma survivors

Background: Network analysis has gained increasing attention as a new framework to study complex associations between symptoms of post-traumatic stress disorder (PTSD). A number of studies have been published to investigate symptom networks on different sets of symptoms in different populations, and the findings have been inconsistent. Objective: We aimed to extend previous research by testing whether differences in PTSD symptom networks can be found in survivors of type I (single event; sudden and unexpected, high levels of acute threat) vs. type II (repeated and/or protracted; anticipated) trauma (with regard to their index trauma). Method: Participants were trauma-exposed individuals with elevated levels of PTSD symptomatology, most of whom (94%) were undergoing assessment in preparation for PTSD treatment in several treatment centres in Germany and Switzerland (n = 286 with type I and n = 187 with type II trauma). We estimated Bayesian Gaussian graphical models for each trauma group and explored group differences in the symptom network. Results: First, for both trauma types, our analyses identified the edges that were repeatedly reported in previous network studies. Second, there was decisive evidence that the two networks were generated from different multivariate normal distributions, i.e. the networks differed on a global level. Third, explorative edge-wise comparisons showed moderate or strong evidence for specific 12 edges. Edges which emerged as especially important in distinguishing the networks were between intrusions and flashbacks, highlighting the stronger positive association in the group of type II trauma survivors compared to type I survivors. Flashbacks showed a similar pattern of results in the associations with detachment and sleep problems (type II > type I). Conclusion: Our findings suggest that trauma type contributes to the heterogeneity in the symptom network. Future research on PTSD symptom networks should include this variable in the analyses to reduce heterogeneity

Comparing PTSD symptom networks in type I vs. type II trauma survivors

Background: Network analysis has gained increasing attention as a new framework to study complex associations between symptoms of post-traumatic stress disorder (PTSD). A number of studies have been published to investigate symptom networks on different sets of symptoms in different populations, and the findings have been inconsistent. Objective: We aimed to extend previous research by testing whether differences in PTSD symptom networks can be found in survivors of type I (single event; sudden and unexpected, high levels of acute threat) vs. type II (repeated and/or protracted; anticipated) trauma (with regard to their index trauma). Method: Participants were trauma-exposed individuals with elevated levels of PTSD symptomatology, most of whom (94%) were undergoing assessment in preparation for PTSD treatment in several treatment centres in Germany and Switzerland (n = 286 with type I and n = 187 with type II trauma). We estimated Bayesian Gaussian graphical models for each trauma group and explored group differences in the symptom network. Results: First, for both trauma types, our analyses identified the edges that were repeatedly reported in previous network studies. Second, there was decisive evidence that the two networks were generated from different multivariate normal distributions, i.e. the networks differed on a global level. Third, explorative edge-wise comparisons showed moderate or strong evidence for specific 12 edges. Edges which emerged as especially important in distinguishing the networks were between intrusions and flashbacks, highlighting the stronger positive association in the group of type II trauma survivors compared to type I survivors. Flashbacks showed a similar pattern of results in the associations with detachment and sleep problems (type II > type I). Conclusion: Our findings suggest that trauma type contributes to the heterogeneity in the symptom network. Future research on PTSD symptom networks should include this variable in the analyses to reduce heterogeneity

Non-invasive testing for early detection of neovascular macular degeneration in unaffected second eyes of older adults : EDNA diagnostic accuracy study

Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 8. See the NIHR Journals Library website for further project information.Peer reviewedPublisher PD