Catalyst nanoparticle growth dynamics and their influence on product morphology in a CVD process for continuous carbon nanotube synthesis

Extrapolating the properties of individual CNTs into macro-scale CNT materials using a continuous and cost effective process offers enormous potential for a variety of applications. The floating catalyst chemical vapor deposition (FCCVD) method discussed in this paper bridges the gap between generating nano- and macro-scale CNT material and has already been adopted by industry for exploitation. A deep understanding of the phenomena occurring within the FCCVD reactor is thereby key to producing the desired CNT product and successfully scaling up the process further. This paper correlates information on decomposition of reactants, axial catalyst nanoparticle dynamics and the morphology of the resultant CNTs and shows how these are strongly related to the temperature and chemical availability within the reactor. For the first time, in-situ measurements of catalyst particle size distributions coupled with reactant decomposition profiles and a detailed axial SEM study of formed CNT materials reveal specific domains that have important implications for scale-up. A novel observation is the formation, disappearance and reformation of catalyst nanoparticles along the reactor axis, caused by their evaporation and re-condensation and mapping of different CNT morphologies as a result of this process.The authors thank Qflo Ltd for providing funding towards this research, C. Hoecker additionally thanks Churchill College Cambridge for financial support, M. Bajada gratefully acknowledges financial support through the 'Master it! Scholarship Scheme'.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1016/j.carbon.2015.09.05

Scalable Photocatalyst Panels for Photoreforming of Plastic, Biomass and Mixed Waste in Flow.

Solar-driven reforming uses sunlight and a photocatalyst to generate H2 fuel from waste at ambient temperature and pressure. However, it faces practical scaling challenges such as photocatalyst dispersion and recyclability, competing light absorption by the waste solution, slow reaction rates and low conversion yields. Here, the immobilisation of a noble-metal-free carbon nitride/nickel phosphide (CNx |Ni2 P) photocatalyst on textured glass is shown to overcome several of these limitations. The 1 cm2 CNx |Ni2 P panels photoreform plastic, biomass, food and mixed waste into H2 and organic molecules with rates comparable to those of photocatalyst slurries. Furthermore, the panels enable facile photocatalyst recycling and novel photoreactor configurations that prevent parasitic light absorption, thereby promoting H2 production from turbid waste solutions. Scalability is further verified by preparing 25 cm2 CNx |Ni2 P panels for use in a custom-designed flow reactor to generate up to 21 μmolH 2  m-2  h-1 under "real-world" (seawater, low sunlight) conditions. The application of inexpensive and readily scalable CNx |Ni2 P panels to photoreforming of a variety of real waste streams provides a crucial step towards the practical deployment of this technology

Diffusion MRI : from basic principles to clinical applications

Diffusion MRI (dMRI) is widely used by clinicians and radiologists to diagnose neurological disorders, in particular stroke. The most commonly encountered diffusion technique in the clinic is simple diffusion weighted imaging and apparent diffusion coefficient (ADC) mapping. However, dMRI can tap into a wealth of data that is usually overlooked by clinicians. While most of this ‘additional’ information is primarily used in a research setting, it is beginning to permeate the clinic. Despite the widespread use of dMRI, clinicians who do not have radiological training may not feel comfortable with the basic principles that underlie this modality. This paper’s aim is to make the fundamentals of the technique accessible to doctors and allied health practitioners who have an interest in dMRI and who use it clinically. It progresses to discuss how these measures can be used.peer-reviewe

Interfacing single-atom catalysis with continuous-flow organic electrosynthesis

The global warming crisis has sparked a series of environmentally cautious trends in chemistry, allowing us to rethink the way we conduct our synthesis, and to incorporate more earth-abundant materials in our catalyst design. “Single-atom catalysis” has recently appeared on the catalytic spectrum, and has truly merged the benefits that homogeneous and heterogeneous analogues have to offer. Further still, the possibility to activate these catalysts by means of a suitable electric potential could pave the way for a true integration of diverse synthetic methodologies and renewable electricity. Despite their esteemed benefits, single-atom electrocatalysts are still limited to the energy sector (hydrogen evolution reaction, oxygen reduction, etc.) and numerous examples in the literature still invoke the use of precious metals (Pd, Pt, Ir, etc.). Additionally, batch electroreactors are employed, which limit the intensification of such processes. It is of paramount importance that the field continues to grow in a more sustainable direction, seeking new ventures into the space of organic electrosynthesis and flow electroreactor technologies. In this piece, we discuss some of the progress being made with earth abundant homogeneous and heterogeneous electrocatalysts and flow electrochemistry, within the context of organic electrosynthesis, and highlight the prospects of alternatively utilizing single-atom catalysts for such applications

Spatio-temporal analysis of air pollution data in Malta

Air pollution measurements display patterns over space and time allowing for spatio-temporal modelling, through which pollution concentrations and trends can be analysed. In Malta, the MEPA (Malta Environment and Planning Authority) collects monthly averaged data for various pollutants from a network of 123 diffusion tubes located around the Islands (Figure 1). This preliminary study uses data associated with traffic, that is nitrogen dioxide (NO2) and benzene, collected monthly between the period 2004 and 2010 with the objectives to i) develop a computationally efficient method that best describes the data; ii) determine the level of dependency of each site on neighbouring ones and iii) identify any factors that affect the behaviour and patterns of pollution. Results will show that generally there is a low spatial dependency between close sites, thus implying that local sources, rather than diffusion, have a predominant effect on the measurements. This analysis will prove valuable in MEPA’s redistribution exercise of the diffusion tube network to determine which sites are necessary to retain and which sites can be removed without significantly affecting the information gathered.peer-reviewe

A Precious-Metal-Free Hybrid Electrolyzer for Alcohol Oxidation Coupled to CO2 -to-Syngas Conversion.

Electrolyzers combining CO2 reduction (CO2 R) with organic substrate oxidation can produce fuel and chemical feedstocks with a relatively low energy requirement when compared to systems that source electrons from water oxidation. Here, we report an anodic hybrid assembly based on a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) electrocatalyst modified with a silatrane-anchor (STEMPO), which is covalently immobilized on a mesoporous indium tin oxide (mesoITO) scaffold for efficient alcohol oxidation (AlcOx). This molecular anode was subsequently combined with a cathode consisting of a polymeric cobalt phthalocyanine on carbon nanotubes to construct a hybrid, precious-metal-free coupled AlcOx-CO2 R electrolyzer. After three-hour electrolysis, glycerol is selectively oxidized to glyceraldehyde with a turnover number (TON) of ≈1000 and Faradaic efficiency (FE) of 83 %. The cathode generated a stoichiometric amount of syngas with a CO:H2 ratio of 1.25±0.25 and an overall cobalt-based TON of 894 with a FE of 82 %. This prototype device inspires the design and implementation of nonconventional strategies for coupling CO2 R to less energy demanding, and value-added, oxidative chemistry

Developing sustainability learning in business school curricula–productive boundary objects and participatory processes

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Sustainability learning is holistic and complex as it draws on diverse disciplines and can be interpreted differently within individual pedagogies. Embedding sustainability across and within business schools relies on developing suitable boundary objects. These may include representations such as models, frameworks or classificatory schemes that are malleable enough to be adapted for use within the disparate disciplines and pedagogies, yet durable enough to be recognisable and to maintain consistency across them. Boundary objects thus allow the sharing of ways of knowing or practice across various social boundaries. This paper outlines how participatory curriculum development processes can enable sustainability to be embedded in a business school curriculum. Distinct phases of the process were marked by different ways of knowing, as disciplinary-specific academics developed and embedded sustainability into and across curricula. Boundary objects were both outcomes and productive facilitators of this process. They acted as catalysts and attracted ongoing processes of dialogue, debate and meaning-making between these academics. The institutional context provided enabling conditions to legitimize outcomes from the participatory process. The process may be replicable in other business schools by the use of boundary objects

Types of Stem Cells in Regenerative Medicine: A Review

Two basic and clinical researches accomplished during the recent years on embryonic and adult stem cells constituted a mutation in regenerative therapy. These cells can be used for treating some degenerative diseases. Between them, age-related functional defects, hematopoietic and immune system disorders, heart failures, chronic liver injuries, diabetes, Parkinson’s and Alzheimer’s diseases, arthritis and muscular, skin, lung, eye, and digestive disorders, aggressive and regressive cancers can be treated by cell therapies. This review focused on types of stem cells used in regenerative medicine

Mesenchymal stem cells rescue cardiomyoblasts from cell death in an in vitro ischemia model via direct cell-to-cell connections

<p>Abstract</p> <p>Background</p> <p>Bone marrow derived mesenchymal stem cells (MSCs) are promising candidates for cell based therapies in myocardial infarction. However, the exact underlying cellular mechanisms are still not fully understood. Our aim was to explore the possible role of direct cell-to-cell interaction between ischemic H9c2 cardiomyoblasts and normal MSCs. Using an in vitro ischemia model of 150 minutes of oxygen glucose deprivation we investigated cell viability and cell interactions with confocal microscopy and flow cytometry.</p> <p>Results</p> <p>Our model revealed that adding normal MSCs to the ischemic cell population significantly decreased the ratio of dead H9c2 cells (H9c2 only: 0.85 ± 0.086 vs. H9c2+MSCs: 0.16 ± 0.035). This effect was dependent on direct cell-to-cell contact since co-cultivation with MSCs cultured in cell inserts did not exert the same beneficial effect (ratio of dead H9c2 cells: 0.90 ± 0.055). Confocal microscopy revealed that cardiomyoblasts and MSCs frequently formed 200-500 nm wide intercellular connections and cell fusion rarely occurred between these cells.</p> <p>Conclusion</p> <p>Based on these results we hypothesize that mesenchymal stem cells may reduce the number of dead cardiomyoblasts after ischemic damage via direct cell-to-cell interactions and intercellular tubular connections may play an important role in these processes.</p

CD271-selected mesenchymal stem cells from adipose tissue enhance cartilage repair and are less angiogenic than plastic adherent mesenchymal stem cells

CD271 is a marker of bone marrow MSCs with enhanced differentiation capacity for bone or cartilage repair. However, the nature of CD271+ MSCs from adipose tissue (AT) is less well understood. Here, we investigated the differentiation, wound healing and angiogenic capacity of plastic adherent MSCs (PA MSCs) versus CD271+ MSCs from AT. There was no difference in the extent to which PA MSCs and CD271+ MSCs formed osteoblasts, adipocytes or chondrocytes in vitro. In contrast, CD271+ MSCs transplanted into athymic rats significantly enhanced osteochondral wound healing with reduced vascularisation in the repair tissue compared to PA MSCs and control animals; there was little histological evidence of mature articular cartilage formation in all animals. Conditioned medium from CD271+ MSC cultures was less angiogenic than PA MSC conditioned medium, and had little effect on endothelial cell migration or endothelial tubule formation in vitro. The low angiogenic activity of CD271+ MSCs and improved early stage tissue repair of osteochondral lesions when transplanted, along with a comparable differentiation capacity along mesenchymal lineages when induced, suggests that these selected cells are a better candidate than PA MSCs for the repair of cartilaginous tissue