1,211 research outputs found

    Improved Understanding of the Modeled QBO Using MLS Observations and MERRA Reanalysis

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    The Quasi-Biennial Oscillation (QBO) dominates the variability of the tropical stratosphere on interannual time scales. The QBO has been shown to extend its influence into the chemical composition of this region through dynamical mechanisms. We have started our analysis using the realistic QBO internally generated by the Goddard Earth Observing System Version 5 (GEOS-5) general circulation model coupled to a comprehensive stratospheric and tropospheric chemical mechanism forced with observed sea surface temperatures over the past 33 years. We will show targeted comparisons with observations from NASAs Aura satellite Microwave Limb Sounder (MLS) and the Modern Era Retrospective-Analysis for Research and Applications (MERRA) reanalysis to provide insight into the simulation of the primary and secondary circulations associated with the QBO. Using frequency spectrum analysis and multiple linear regression we can illuminate the resulting circulations and deduce the strengths and weaknesses in their modeled representation. Inclusion of the QBO in our simulation improves the representation of the subtropical barriers and overall tropical variability. The QBO impact on tropical upwelling is important to quantify when calculating trends in sub-decadal scale datasets

    Controlled release from zein matrices: Interplay of drug hydrophobicity and pH

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    Purpose: In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and ranitidine. Methods: Caplets were prepared by hot-melt extrusion (HME) and injection moulding (IM). Each of the three model drugs were tested on two drug loadings in various dissolution media. The physical state of the drug, microstructure and hydration behaviour were investigated to build up understanding for the release behaviour from zein based matrix for drug delivery. Results: Drug crystallinity of the caplets increases with drug hydrophobicity. For ranitidine and indomethacin, swelling rates, swelling capacity and release rates were pH dependent as a consequence of the presence of charged groups on the drug molecules. Both hydration rates and release rates could be approached by existing models. Conclusion: Both the drug state as pH dependant electrostatic interactions are hypothesised to influence release kinetics. Both factors can potentially be used factors influencing release kinetics release, thereby broadening the horizon for zein as a tuneable release agent

    A model of the antarctic sink for stratospheric water vapor

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    Lyophilized wafers comprising carrageenan and pluronic acid for buccal drug delivery using model soluble and insoluble drugs

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    Lyophilized muco-adhesive wafers with optimum drug loading for potential buccal delivery have been developed. A freeze-annealing cycle was used to obtain optimized wafers from aqueous gels containing 2% κ-carrageenan (CAR 911), 4% pluronic acid (F127), 4.4% (w/w) polyethylene glycol with 1.8% (w/w) paracetamol or 0.8% (w/w) ibuprofen. Thermogravimetric analysis showed acceptable water content between 0.9 and 1.5%. Differential scanning calorimetry and X-ray diffraction showed amorphous conversion for both drugs. Texture analysis showed ideal mechanical and mucoadhesion characteristics whilst both drugs remained stable over 6 months and drug dissolution at a salivary pH showed gradual release within 2 h. The results show the potential of CAR 911 and F127 based wafers for buccal mucosa drug delivery

    Embrace the good, refuse the bad: Haitian American children's selective engagement with the United States

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    This qualitative research study investigates the perceptions of children, parents, and staff members at a Boston multi-service nonprofit for Haitian immigrants. It is an exploration of how children cultivate their identity, and how a center for immigrants functions in the current sociopolitical climate. There is an evidentiary lacuna of qualitative explorations on children of immigrants’ perceptions and health. The COVID-19 pandemic makes this issue even more temporally relevant, as new data suggests structural factors make marginalized groups, such as people of color and immigrants, more vulnerable to infection and death. This study will contribute to the body of work on children of immigrants’ health by 1) analyzing the unique child perspective, as opposed to focusing entirely on adults or using quantitative child measures, 2) employing qualitative data to create more robust depictions of lived experiences, 3) and situating data in the particular Haiti/U.S. historical, political relationship. This study’s methodology includes ethnographic participant observation during regular visits to a nonprofit organization for immigrants (Fanmi Nou) over the course of several months, semi-structured video interviews with children, parents, and staff members of this organization, and content analysis of documents produced by Fanmi Nou. Through different waves of migration to the United States, children of Haitian immigrants have lived bicultural lives. In the last four years, however, biculturalism and transnationality have come under growing assault. As a reactionary response to overt hostility, parents, staff members at Fanmi Nou, and children themselves, actively promote a Haitian identity in children. Living under an administration characterized by its hostility to immigrants, Haitian American children pick and choose which aspects of American life to welcome and which to reject. Through a multi-service nonprofit organization, these children and their families selectively engage with the U.S. political, educational, and social systems. I argue that these children and this organization strategically support the healthy development of self under these new restrictions

    GOVERNMENT INTERVENTION IN ESG INVESTING: FINANCIAL EFFECTS OF FRANCE’S ENERGY TRANSITION FOR GREEN GROWTH ACT

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    Environmental, social and governance (ESG) investing is gaining popularity in the finance sector by incorporating positive social impact and quantitative and qualitative risk factors. Investors using ESG strategies are assessing the impact of this shift on portfolio returns, and governments are regulating ESG data reporting. This study builds on prior research to (1) determine the impact of government reporting standards on ESG investment outcomes and long-term returns of portfolios and (2) address changes in the returns of ESG-focused investment strategies using the largest French companies before and after the implementation of the Energy Transition for Green Growth Act, a 2016 French law impacting ESG reporting standards. The results outline differences in returns between high and low-scoring ESG portfolios in France and changes in these portfolios before and after the regulation passed. The report concludes that France’s regulation increased average ESG scores but did not have a statistically significant impact on the average returns from ESG-focused portfolios.Bachelor of Business Administratio

    Silk fibroin microparticles as carriers for delivery of human recombinant BMPs: physical characterization and drug release

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    Bone morphogenetic proteins (BMPs) are cytokines with strong ability to promote new bone formation. Herein, we report the use of silk fibroin microparticles as carriers for the delivery of BMP-2, BMP-9 or BMP-14. BMP-containing fibroin microparticles were prepared by a mild methodology using dropwise addition of ethanol, exhibiting mean diameters of 2.7 ± 0.3 μm. Encapsulation efficiencies varied between 67.9 ± 6.1 % and 97.7 ± 2.0 % depending on the type and the amount of BMP loaded. Release kinetics showed that BMP-2, BMP-9 and BMP-14 were released in two phases profile, with a burst release in the first two days followed by a slower release, for a period of 14 days. The release data were best explained by Korsmeyer’s model and the Fickian model of drug diffusion. Silk fibroin microparticles can offer a promising approach for the sustained delivery of different BMPs in tissue engineering applications.The authors wish to acknowledge. Susana Moreira, Elsa Ribeiro and Katharina Schobitz for critical input. This work was supported by Fundacao para a Ciencia e Tecnologia (PhD grant SFRH/BD/17049/2004), project ElastM POCI/CTM/57177/2004 funded by FEDER and the Fundacao para a Ciencia e Tecnologia; Marie Curie Alea Jacta EST short-term grant (MEST-CT-2004-8104) and European STREP Project HIPPOCRATES (NMP3-CT-2003-505758). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)

    Functional characterisation and antimicrobial efficiency assessment of smart nanohydrogels containing natamycin incorporated into polysaccharide-based films

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    The potential application of polysaccharide-based films containing smart nanohydrogels for the controlled release of food preservatives is demonstrated here. Smart active packaging is the most promising alternative to traditional packaging as it provides a controlled antimicrobial effect, which allows reducing the amount of preservatives in the food bulk, releasing them only on demand. This work evaluates the usefulness of smart thermosensitive poly(N-isopropylacrylamide) (PNIPA) nanohydrogels with or without acrylic acid (AA) incorporated into polysaccharide-based films (GA) to transport natamycin and release it as a response to environmental triggers. Release kinetics in liquid medium from GA films containing PNIPA/AA nanohydrogels (GA-PNIPA(5) and GA-PNIPA-20AA(5)) presented a characteristic feature regarding the films without nanohydrogels that was the appearance of a lag time in natamycin release, able to reach values of around 35 h. Another important feature of natamycin release kinetics was the fact that the release from GA-PNIPA/AA films only occurred when temperature was increased, so that the natamycin release was restricted to when there is a risk of growth of microorganisms that cause food spoilage or the development of pathogenic microorganisms. Additionally, it could be observed that the relative fraction of natamycin released from GA-PNIPA/AA films was significantly (p<0.05) higher than that released from GA films loaded with the same amount of free natamycin. It can be hypothesised that the encapsulation of natamycin into nanohydrogels helped it to be released from GA films, creating reservoirs of natamycin into the films and, therefore, facilitating its diffusion through the film matrix when the nanohydrogel collapses. In a solid medium, the low water availability limited natamycin release from GA-PNIPA/AA films restricting the on/off release mechanism of PNIPA/AA nanohydrogels and favouring the hydrophobic interactions between natamycin and polymer chains at high temperatures. Despite the low natamycin release in solid media, antimicrobial efficiency of GA-PNIPA(5) films containing natamycin in acidified agar plates was higher than that obtained with GA films without natamycin and GA films with free natamycin, probably due to the protecting effect against degradation when natamycin was included in the nanohydrogels, allowing its release only when the temperature increased.Clara Fucinos and Miguel A. Cerqueira are recipients of a fellowship (SFRH/BPD/87910/2012 and SFRH/BPD/72753/2010, respectively) from the Fundacao para a Ciencia e Tecnologia (FCT, POPH-QREN, and FSE Portugal). The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", Ref. NORTE-07-0124-FEDER-000028 co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER and the project from the "Ministerio de Educacion y Ciencia" (Spain) "Nanohidrogeles inteligentes sensibles a cambios de pH y Temperatura: Diseno, sintesis y aplicacion en terapia del cancer y el envasado activo de alimentos", Ref. MAT2010-21509-C03-01
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