Dynamic behaviour of an electrolyser with a two phase solid-liquid electrolyte : Part I : spectral analysis of potential fluctuations

The dynamic behaviour of a simplified electrolyser with a two phase solid-liquid electrolyte was investigated. The current-voltage curve and the impedance of the working electrode (current collector) was measured. In addition the fluctuations of the working electrode potential and of the electrolyte resistance close to the electrode were analysed, especially by spectral analysis. Conductive zinc-coated polystyrene beads and insulating glass beads were compared. For glass beads the kinetics were controlled by ohmic drop fluctuations due to the collisions of the beads onto the collector. With zinc beads the charge exchanges between the beads and the current collector were also observed and contributed to the potential fluctuations. A complementary analysis of the elementary potential and electrolyte resistance transients will be reported in Part II; the electrochemical behaviour of the collector will then be modelled

Liposomes : Formulation and characterisation as contrast agents and as vaccine delivery systems

Liposome systems are well reported for their activity as vaccine adjuvants; however novel lipid-based microbubbles have also been reported to enhance the targeting of antigens into dendritic cells (DCs) in cancer immunotherapy (Suzuki et al 2009). This research initially focused on the formulation of gas-filled lipid coated microbubbles and their potential activation of macrophages using in vitro models. Further studies in the thesis concentrated on aqueous-filled liposomes as vaccine delivery systems. Initial work involved formulating and characterising four different methods of producing lipid-coated microbubbles (sometimes referred to as gas-filled liposomes), by homogenisation, sonication, a gas-releasing chemical reaction and agitation/pressurisation in terms of stability and physico-chemical characteristics. Two of the preparations were tested as pressure probes in MRI studies. The first preparation composed of a standard phospholipid (DSPC) filled with air or nitrogen (N2), whilst in the second method the microbubbles were composed of a fluorinated phospholipid (F-GPC) filled with a fluorocarbon saturated gas. The studies showed that whilst maintaining high sensitivity, a novel contrast agent which allows stable MRI measurements of fluid pressure over time, could be produced using lipid-coated microbubbles. The F-GPC microbubbles were found to withstand pressures up to 2.6 bar with minimal damage as opposed to the DSPC microbubbles, which were damaged at above 1.3 bar. However, it was also found that DSPC-filled with N2 microbubbles were also extremely robust to pressure and their performance was similar to that of F-GPC based microbubbles. Following on from the MRI studies, the DSPC-air and N2 filled lipid-based microbubbles were assessed for their potential activation of macrophages using in vitro models and compared to equivalent aqueous-filled liposomes. The microbubble formulations did not stimulate macrophage uptake, so studies thereafter focused on aqueous-filled liposomes. Further studies concentrated on formulating and characterising, both physico-chemically and immunologically, cationic liposomes based on the potent adjuvant dimethyldioctadecylammonium (DDA) and immunomodulatory trehalose dibehenate (TDB) with the addition of polyethylene glycol (PEG). One of the proposed hypotheses for the mechanism behind the immunostimulatory effect obtained with DDA:TDB is the ‘depot effect’ in which the liposomal carrier helps to retain the antigen at the injection site thereby increasing the time of vaccine exposure to the immune cells. The depot effect has been suggested to be primarily due to their cationic nature. Results reported within this thesis demonstrate that higher levels of PEG i.e. 25 % were able to significantly inhibit the formation of a liposome depot at the injection site and also severely limit the retention of antigen at the site. This therefore resulted in a faster drainage of the liposomes from the site of injection. The versatility of cationic liposomes based on DDA:TDB in combination with different immunostimulatory ligands including, polyinosinic-polycytidylic acid (poly (I:C), TLR 3 ligand), and CpG (TLR 9 ligand) either entrapped within the vesicles or adsorbed onto the liposome surface was investigated for immunogenic capacity as vaccine adjuvants. Small unilamellar (SUV) DDA:TDB vesicles (20-100 nm native size) with protein antigen adsorbed to the vesicle surface were the most potent in inducing both T cell (7-fold increase) and antibody (up to 2 log increase) antigen specific responses. The addition of TLR agonists poly(I:C) and CpG to SUV liposomes had small or no effect on their adjuvanticity. Finally, threitol ceramide (ThrCer), a new mmunostimulatory agent, was incorporated into the bilayers of liposomes composed of DDA or DSPC to investigate the uptake of ThrCer, by dendritic cells (DCs), and presentation on CD1d molecules to invariant natural killer T cells. These systems were prepared both as multilamellar vesicles (MLV) and Small unilamellar (SUV). It was demonstrated that the IFN-g secretion was higher for DDA SUV liposome formulation (p<0.05), suggesting that ThrCer encapsulation in this liposome formulation resulted in a higher uptake by DCs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Dynamic behaviour of an electrolyser with a two phase solid-liquid electrolyte : Part I : spectral analysis of potential fluctuations

The dynamic behaviour of a simplified electrolyser with a two phase solid-liquid electrolyte was investigated. The current-voltage curve and the impedance of the working electrode (current collector) was measured. In addition the fluctuations of the working electrode potential and of the electrolyte resistance close to the electrode were analysed, especially by spectral analysis. Conductive zinc-coated polystyrene beads and insulating glass beads were compared. For glass beads the kinetics were controlled by ohmic drop fluctuations due to the collisions of the beads onto the collector. With zinc beads the charge exchanges between the beads and the current collector were also observed and contributed to the potential fluctuations. A complementary analysis of the elementary potential and electrolyte resistance transients will be reported in Part II; the electrochemical behaviour of the collector will then be modelled

Corrosion process in NaCl/Na2SO4 solutions of AISI 316L stainless steel treated by ionic nitriding

This work is a corrosion study of an AISI 316L austenitic stainless steel after different plasma ion nitriding conditions. The properties of the coated AISI 316L were measured. The corrosion resistance was evaluated by cyclic voltammetry and salt spray testing. Sample surfaces were characterised by SEM and the phase determination with XRD analysis. Nanohardness was determined by using a Vickers indenter. The nitrided samples treated at 400°C, in a gaseous mixture of 5%N2 and 95%H2 for 4 and 5 h, had the best corrosion resistance. For the salt spray test, where the potential range is near the equilibrium potential, the nitrided material presented a reduced corrosion resistance. Through the control of the process parameters it is possible to improve the stainless steel surface hardness, combined with a good corrosion resistance. The highest value of temperature and N2 proportion increased the surface roughness and hardness, though it caused a decrease in corrosion resistance

The P2X7 Receptor Is Overexpressed in the Lesional Skin of Subjects Affected by Hidradenitis Suppurativa: A Preliminary Study

Background: P2X receptors (P2XRs) are plasma membrane channels involved in the modulation of immune responses. The role of the P2X7 receptor (P2X7R) has never been investigated in hidradenitis suppurativa (HS), which is a recurrent skin disease characterized by inflammatory nodules, scarring, and suppuration. Objective: Our aim was to investigate by immunohistochemistry (IHC) P2X7R, NLRP3 (NOD-like receptor family, pyrin domain-containing 3), and interleukin-1\u3b2 (IL-1\u3b2) expression in HS lesions compared to healthy control (HC) skin. Method: The intensity of IHC immunostaining was semi-quantitatively graded for keratinocytes, neutrophils, lymphocytes, and monocytes. Statistical significance was assessed by the Mann-Whitney U test, Cohen's \u3ba coefficient, and \u3c72 test. Results: A total of 59 samples, 31 from HS and 28 from HC, were collected and analysed. In skin keratinocytes, lymphocytes, and monocytes, but not in neutrophils, P2X7R and NLRP3 protein expression was significantly increased in HS versus the HC group. IL-1\u3b2 protein expression was also higher in HS versus the HC group both in skin keratinocytes and in the inflammatory infiltrate. Cohen's \u3ba correlation coefficients for the expression of P2X7R versus NLRP3 or IL-1\u3b2 in skin keratinocytes were significant (\u3ba = 0.43 and 0.34, respectively). The same association between P2X7R and NLRP3 or IL-1\u3b2 was confirmed by \u3c72 tests. Conclusion: P2X7R, NLRP3, and IL-1\u3b2 are overexpressed, and therefore the entire P2X7R/NLRP3/IL-1\u3b2 pro-inflammatory axis is likely overactive in the skin of HS patients. This observation might provide clues to the pathogenesis of this disease and suggest novel therapies and markers of disease activity