Nanocluster Evolution in D9 Austenitic Steel under Neutron and Proton Irradiation.

Austenitic stainless steel D9 is a candidate for Generation IV nuclear reactor structural materials due to its enhanced irradiation tolerance and high-temperature creep strength compared to conventional 300-series stainless steels. But, like other austenitic steels, D9 is susceptible to irradiation-induced clustering of Ni and Si, the mechanism for which is not well understood. This study utilizes atom probe tomography (APT) to characterize the chemistry and morphology of Ni-Si nanoclusters in D9 following neutron or proton irradiation to doses ranging from 5-9 displacements per atom (dpa) and temperatures ranging from 430-683 °C. Nanoclusters form only after neutron irradiation and exhibit classical coarsening with increasing dose and temperature. The nanoclusters have Ni3Si stoichiometry in a Ni core-Si shell structure. This core-shell structure provides insight into a potentially unique nucleation and growth mechanism-nanocluster cores may nucleate through local, spinodal-like compositional fluctuations in Ni, with subsequent growth driven by rapid Si diffusion. This study underscores how APT can shed light on an unusual irradiation-induced nanocluster nucleation mechanism active in the ubiquitous class of austenitic stainless steels.

Techno-economic and life cycle analysis of circular phosphorus systems in agriculture.

Fertilizer runoff is a global nuisance that disrupts biogeochemical cycles of nitrogen and phosphorus. We perform techno-economic and life cycle analyses of selected approaches for enabling a circular economy of phosphorus. We consider four schemes: capturing P with ion-exchange resins followed by precipitation, interception by wetland and recovery in char after biomass pyrolysis, removal by bioreactor and recovery in char after bioreactor substrate pyrolysis, and using legacy phosphorus accumulated in a saturated wetland to grow crops by wetlaculture. For each system, we analyze the mass flow, calculate the degree of circularity, and examine the feasibility by techno-economic and life cycle analyses. We find that although ion exchange outperforms the others, the associated economic and emissions burden are too high. Approaches that rely on wetlands are most economically attractive and can have lower impact. However, without policy interventions, the linear economy of phosphorus is likely to remain economically most attractive.

Success of Dental Implant Influenced by Abutment Types and Loading Protocol.

Background: Dental implants are considered better, latest, and most advanced technique of teeth replacement in present times with more teeth loss and increased related concerns. Aims: The present clinical trial was carried out to assess marginal bone loss and implant failure in immediate and delayed loading implants. The study also evaluated healing using Polymerase Chain Reaction (PCR) and the effect of risk factors on marginal bone loss. Materials and Methods: The 44 subjects were randomly divided into two groups with immediate loading and delayed loading protocols. Various soft-tissue parameters were seen clinically. Quantitative PCR was done to detect biomarkers. The collected data were subjected to statistical evaluation with a level of significance at P < 0.05 and the results were formulated. Results: Concerning marginal bone loss, it was seen that for delayed loading, the bone loss at the implant level was 1.52 ± 0.14, 0.19 ± 0.11, and 0.40 ± 0.12, respectively, at placement, 1 and 2 years. Plaque and mucosal bleeding scores were low at the time of placement with respective values of 0.96 ± 0.12 and 28.42 ± 3.15 for the delayed loading group and 0.98 ± 0.11 and 30.24 ± 3.15 for the immediate loading group. Tartrate-resistant acid phosphatase (TRAP) showing remodeling was high at 3 months in delayed loading (13.3 ± 8.5). Alkaline Phosphatase (ALP) was highest in delayed loading at 3 months (25.2 ± 7.7) and immediate loading at 2 days (32.6 ± 13). Conclusion: Both immediate loading and delayed loading implants show similar results in terms of bone loss, soft-tissue parameters, and biomarkers in sulcular fluids with relatively few and manageable complications.

Sustainable and 'smart' restructuring around the making of mega and world-class cities in India: a critical review.

COVID-19 has posed newer questions on urban vulnerabilities in India and showcased the importance of acting effectively towards a vision of sustainable urbanization. Several studies during the pandemic explored the need to make cities socially inclusive and ecologically resilient. The Indian Smart Cities Mission is the flagship urban project that envisions economic growth and ensures technology-induced quality of life in tune with global city-making projects like eco-city, world-class city, green city, etc. Here, we critically examine a range of such neoliberal urban projects and explore the extent to which these cities in their 'smart' restructuring embrace a holistic vision of sustainability. We analyse three urban renewal projects: the Lavasa eco-city, the Rajarhat green-city, and the Dholera smart city, arguing why a case-study based approach is significant to study the connection between policy promises and actual socio-environmental realities. Our empirical explorations reveal that processes and practices involved in the making of these projects are 'utopian'; in reality, they tend to uproot the existing urban ecological buffers, critically impacting the quality of urban life across classes. Beyond the capitalist logic of 'accumulation by dispossession', we finally lay out the need to imagine urban commons as scripted with memories, desires, plurality of use, users, and ways of living, and thus to situate the urban planning in practical visions of sustainability and environmental resilience.

Falling "fortresses": Unlocking Governance Entanglements and Shifting Knowledge Paradigms to Counter Climate Change Threats in Biodiversity Conservation.

Biodiversity conservation is facing unprecedented challenges at the intersection of rapidly changing climates, widespread ecosystem degradation under the influence of global warming and resultant human tragedies over livelihood, habitation, adaptation and coping needs. These challenges are more acute across biodiversity hotspots in the Global South. This study disentangles the complex interplay to propose alternative paradigms of governance and policy thinking necessary for sustainable biodiversity conservation. Climate change impacts are exposing critical deficiencies of 'scientific forest management' pursued for over a century. For example, recurrent disasters and ecological shifts are increasingly obfuscating cognitive and physical boundaries between the reserve forest and human habitations; putting additional stress on livelihoods which in turn escalate pressures on the forest commons and fuel further conflicts between conservation governance and local communities. Instead of assisting in adaptation, the existing conservation governance mechanisms are producing further conflicts between humans and non-humans; livelihoods and conservation; disaster management and development. Conducted in the Sundarbans Biosphere Reserve -world's largest mangrove forest ecosystem and a climate change hotspot located along the Bay of Bengal across India and Bangladesh -the study finds an urgent need of rethinking and recalibrating biodiversity conservation in the times of climate change. However, institutional and market-based approaches such as promoting ecotourism or mangrove plantations may have little impact in this regard, the study finds. Instead, integrating cultural ecosystem services and co-producing knowledge will be critical to tackle the entanglements of climate change and its impacts on local lives, livelihoods and biodiversity conservation.

Influence of field conditions on quantitative analysis of single crystal thorium dioxide by atom probe tomography.

Atom probe tomography (APT), a 3D microscopy technique, has great potential to reveal atomic scale compositional variations, such as those associated with irradiation damage. However, obtaining accurate compositional quantification by APT for high bandgap materials is a longstanding challenge, given the sensitivity to field evaporation parameters and inconsistent behaviors across different oxides. This study investigates the influence of APT laser energy and specimen base temperature on compositional accuracy in single crystal thoria (ThO2). ThO2 has a broad range of applications, including advanced nuclear fuels, sensors, lasers and scintillators, electrodes, catalysis, and photonics and optoelectronics. The expected stoichiometry of ThO2 is achieved at APT base temperature of 24 K and laser energy of 100 pJ. To overcome mass resolution limitations associated with significant thermal tails, Bayesian methods are applied to deconvolute ion identity within the mass spectra. This approach affirms that the parameters chosen are appropriate for APT analysis of ThO2.