Structural Characterization of Metal Hydrides for Energy Applications

Hydrogen can be an unlimited source of clean energy for future because of its very high energy density compared to the conventional fuels like gasoline. An efficient and safer way of storing hydrogen is in metals and alloys as hydrides. Light metal hydrides, alanates and borohydrides have very good hydrogen storage capacity, but high operation temperatures hinder their application. Improvement of thermodynamic properties of these hydrides is important for their commercial use as a source of energy. Application of pressure on materials can have influence on their properties favoring hydrogen storage. Hydrogen desorption in many complex hydrides occurs above the transition temperature. Therefore, it is important to study the physical properties of the hydride compounds at ambient and high pressure and/or high temperature conditions, which can assist in the design of suitable storage materials with desired thermodynamic properties. ^ The high pressure-temperature phase diagram, thermal expansion and compressibility have only been evaluated for a limited number of hydrides so far. This situation serves as a main motivation for studying such properties of a number of technologically important hydrides. Focus of this dissertation was on X-ray diffraction and Raman spectroscopy studies of Mg2FeH6, Ca(BH4) 2, Mg(BH4)2, NaBH4, NaAlH4, LiAlH4, LiNH2BH3 and mixture of MgH 2 with AlH3 or Si, at different conditions of pressure and temperature, to obtain their bulk modulus and thermal expansion coefficient. These data are potential source of information regarding inter-atomic forces and also serve as a basis for developing theoretical models. Some high pressure phases were identified for the complex hydrides in this study which may have better hydrogen storage properties than the ambient phase. The results showed that the highly compressible B-H or Al-H bonds and the associated bond disordering under pressure is responsible for phase transitions observed in brorohydrides or alanates. Complex hydrides exhibited very high compressibility suggesting possibility to destabilize them with pressure. With high capacity and favorable thermodynamics, complex hydrides are suitable for reversible storage. Further studies are required to overcome the kinetic barriers in complex hydrides by catalytic addition. A comparative study of the hydride properties with that of the constituting metal, and their inter relationships were carried out with many interesting features.^

Adapting Mpowerment to a Rural Area

As HIV/AIDS continues to disproportionately impact men who have sex with men (MSM) (CDC, 2010a), effective and timely prevention strategies for this population must be developed. Specifically, evidence-based interventions that can be easily adapted and have proven effectiveness are needed. Hence, the purpose of the current study was to assess the impact of the Mpowerment Project (Hayes, Rebchook, & Kegeles, 2003), a community level HIV prevention program originally designed for young urban gay men, when adapted for rural gay men. The Mpowerment Project is recognized as evidence- based intervention by the CDC (CDC, 2009b). The current study is an extension of this research, assessing Mpowerment model fidelity and the behavioral and attitudinal changes that occurred among participants. Data were collected from participants in a rural area of southeast Idaho from 2002-2004. Data were collected prior to M-Group participation and at a three months follow-up. The 66 individuals completing the M-Group pre and posttest assessment also attended a minimum of three study events and a maximum of 226 events. Results revealed no significant changes in attitudinal variables and all but one behavioral variable among Rural Mpowerment (R-MP) participants. The one significant behavior change was an increase in reported safer sex discussion among friends, indicating a possible change in the social norm regarding safer sex. Results also indicate that program fidelity was maintained and the Mpowerment Project is adaptable to rural areas. However, there was no indication of attitudinal changes in participants of this study. There were no changes in behavioral variables aside from discussion about safer sex with friends increasing. The lack of evidence-based interventions for rural gay men highlights the need for further research on the community impact of the Mpowerment Project on rural participants.

Bahamian men's sexual risks for HIV infection

Heterosexual adult men have been a neglected population that is at risk for HIV infection. In an era burdened by the devastation caused by HIV, it is alarming that risky sexual behavior continues to be a problem among heterosexuals. Heterosexual sexual behavior has contributed to a growing trend of HIV transmission in the Caribbean where the average prevalence in the adult population is 5%. Despite the availability of condoms and HIV prevention efforts of many Caribbean public health departments to reduce the spread of the disease, there appears to be barriers to safer sex practices. Guided by the theory of planned behavior, a descriptive correlational design was used with 185 Bahamian men ages 18 years and older to (a) examine the relationships among select demographics, masculine ideology, condom attitudes, self-efficacy for condom use, and safer sex behaviors; and (b) identify select predictors of condom use among Bahamian men. Data were collected using four standardized instruments and a demographic questionnaire. The results of this study suggest that masculine ideology, condom attitudes, and condom use self-efficacy are important in explaining 33% variance in safer sex behaviors among Bahamian men. Income (β = −.15, p < .01), masculine ideology (β = −.24, p < .01), condom attitudes, (β = .36, p < .01), and condom use self-efficacy (β = .1, p < .01) were significantly associated with safer sex behaviors. The empirical knowledge obtained from this study will be used to provide a rationale for nurses and policy makers to design and conduct culturally sensitive interventions with an aim of achieving an increase in safer sex behaviors among Bahamian men.^

Adapting Mpowerment to a rural area

As HIV/AIDS continues to disproportionately impact men who have sex with men (MSM) (CDC, 2010a), effective and timely prevention strategies for this population must be developed. Specifically, evidence-based interventions that can be easily adapted and have proven effectiveness are needed. Hence, the purpose of the current study was to assess the impact of the Mpowerment Project (Hayes, Rebchook, & Kegeles, 2003), a community level HIV prevention program originally designed for young urban gay men, when adapted for rural gay men. The Mpowerment Project is recognized as evidence- based intervention by the CDC (CDC, 2009b). The current study is an extension of this research, assessing Mpowerment model fidelity and the behavioral and attitudinal changes that occurred among participants. Data were collected from participants in a rural area of southeast Idaho from 2002-2004. Data were collected prior to M-Group participation and at a three months follow-up. The 66 individuals completing the M-Group pre and posttest assessment also attended a minimum of three study events and a maximum of 226 events. Results revealed no significant changes in attitudinal variables and all but one behavioral variable among Rural Mpowerment (R-MP) participants. The one significant behavior change was an increase in reported safer sex discussion among friends, indicating a possible change in the social norm regarding safer sex. Results also indicate that program fidelity was maintained and the Mpowerment Project is adaptable to rural areas. However, there was no indication of attitudinal changes in participants of this study. There were no changes in behavioral variables aside from discussion about safer sex with friends increasing. The lack of evidence-based interventions for rural gay men highlights the need for further research on the community impact of the Mpowerment Project on rural participants.

Biocompatibility assessment of biosorbable polymer coated nitinol alloys

Owing to an increased risk of aging population and a higher incidence of coronary artery disease (CAD), there is a need for more reliable and safer treatments. Numerous varieties of durable polymer-coated drug eluting stents (DES) are available in the market in order to mitigate in-stent restenosis. However, there are certain issues regarding their usage such as delayed arterial healing, thrombosis, inflammation, toxic corrosion by-products, mechanical stability and degradation. As a result, significant amount of research has to be devoted to the improvement of biodegradable polymer-coated implant materials in an effort to enhance their bioactive response. ^ In this investigation, magneto-electropolished (MEP) and a novel biodegradable polymer coated ternary Nitinol alloys, NiTiTa and NiTiCr were prepared to study their bio and hemocompatibility properties. The initial interaction of a biomaterial with its surroundings is dependent on its surface characteristics such as, composition, corrosion resistance, work of adhesion and morphology. In-vitro corrosion tests such as potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) studies were conducted to determine the coating stability and longevity. In-vitro hemocompatibility studies and HUVEC cell growth was performed to determine their thrombogenic and biocompatibility properties. Critical delamination load of the polymer coated Nitinol alloys was determined using Nano-scratch analysis. Sulforhodamine B (SRB) assays were performed to elucidate the effect of metal ions leached from Nitinol alloys on the viability of HUVEC cells. Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), contact angle meter and X-ray diffraction (XRD) were used to characterize the surface of the alloys. ^ MEP treated and polymer coated (PC) Nitinol alloys displayed a corrosion resistant polymer coating as compared to uncoated alloys. MEP and PC has resulted in reduced Ni and Cr ion leaching from NiTi5Cr and subsequently low cytotoxicity. Thrombogenicity tests revealed significantly less platelet adhesion and confluent endothelial cell growth on polymer coated and uncoated ternary MEP Nitinol alloys. Finally, this research addresses the bio and hemocompatibility of MEP + PC ternary Nitinol alloys that could be used to manufacture blood contacting devices such as stents and vascular implants which can lead to lower U.S. healthcare spending.^

Determinants of Waterpipe and Cigarette Smoking Progression among a School Based Sample of Adolescents in Irbid, Jordan: A Three-Year Longitudinal Study (2008-2011)

The prevalence of waterpipe smoking exceeds that of cigarettes among adolescents in the Middle East where waterpipe is believed as less harmful, less addictive and can be a safer alternative to cigarettes. This dissertation tested the gateway hypothesis that waterpipe can provide a bridge to initiate cigarette smoking, identified the predictors of cigarette smoking progression, and identified predictors of waterpipe smoking progression among a school-based sample of Jordanian adolescents (mean age ± SD) (12.7 ±0.61) years at baseline. Data for this research have been drawn from Irbid Longitudinal Study of smoking behavior, Jordan (2008-2011). The grouped-time survival analysis showed that waterpipe smoking was associated with a higher risk of cigarette smoking initiation compared to never smokers (P < 0.001) and this association was dose dependent (P < 0.001). Predictors of cigarette smoking progression were peer smoking and attending public schools for boys, siblings’ smoking for girls, and the urge to smoke for both genders. Predictors of waterpipe smoking progression were enrollment in public schools, frequent physical activity, and low refusal self-efficacy for boys, ever smoking cigarettes, friends’ and siblings’ waterpipe smoking for girls. Awareness of harms of waterpipe among boys and seeing warning labels on the tobacco packs by girls were protective against waterpipe smoking progression. In Conclusion, waterpipe can serve as a gateway to cigarette smoking initiation among adolescents. Waterpipe and cigarette smoking progressions among initiators were solely family-related among girls, and mainly peer-related among boys. The unique gender differences for both cigarette and waterpipe smoking among Jordanian adolescents in Irbid call for cultural and gender-specific smoking prevention interventions to prevent the progression of smoking among initiators.

Atividades biológicas de extratos salinos de sementes de plantas da caatinga contra Aedes Aegypti e investigação da participação de proteínas bioativas

Dengue fever, currently the most important arbovirus, is transmitted by the bite of the Aedes aegypti mosquito. Given the absence of a prophylactic vaccine, the disease can only be controlled by combating the vector insect. However, increasing reports of resistance and environmental damage caused by insecticides have led to the urgent search for new safer alternatives. Twenty - um plant s eed extracts from the Caatinga were prepared , tested and characterized . Sodium phosphate ( 50 mM pH 8.0) was used as extractor. All extracts showed larvicidal and ovipositional deterrence activity . Extracts of D. grandiflora, E. contortisiliquum, A. cearenses , C. ferrea and C. retusa were able to attract females for posture when in low co ncentration . In the attractive concentrations, the CE of E. contortisiliquum and A. cearenses were able to kill 52% and 100% of the larvae respectively . The extracts of A. cearenses , P. viridiflora, E. velutina, M. urundeuva and S. brasiliensis were also pupicides, while extracts of P. viridiflora, E. velutina, E. contortisiliquum , A. cearenses, A. colubrina, D. grandiflora , B. cheilantha , S. spectabilis, C. pyramidalis, M. regnelli e G. americana displayed adulticidal activity. All extracts were toxic to C. dubia zooplankton . The EB of E. velutina and E. contortisiliquum did not affect the viability of fibroblasts . In all extracts were identified at least two potential insecticidal proteins such as enzyme inhibitors, lectins and chitin - binding proteins and components of secondary metabolism . Considering all bioassays , the extracts from A. cearenses, P. viridiflora, E. contortisiliquum , S. brasiliensis, E. velutina and M. urundeuva were considered the most promising . The E. contortisiliquum extracts was the only one who did not show pupicida activity, indicating that its mechanism of action larvicide and adulticidal is related only to the ingesti on of toxic compounds by insect , so it was selected to be fragmenting. As observed for the CE , th e protein fractions of E. contortisiliquum also showed larvicidal activity, highlighting that F2 showed higher larvicidal activity and lower en vironmental toxicity than the CE source. The reduction in the proteolytic activity of larvae fed with crude extra ct and fractions of E. contortisiliquum suggest ed that the trypsin inhibitors ( ITEc) would be resp onsible for larvicidal activity . However the increase in the purification of this inhibitor resulted in loss of larvicidal activity , but the absence of trypsin inhibitor reduced the effectiveness of the fractions , indicating that the ITEC contributes to the larvicidal activity of this extract. Not been observed larvicidal activity and adulticide in rich fraction vicilin, nor evidence of the contribution o f this molecule for the larvicidal activity of the extract. The results show the potential of seeds from plant extracts of Caatinga as a source of active molecules against insects A. aegypti at different stages of its development cycle, since they are comp osed of different active compounds, including protein nature, which act on different mechanisms should result in the death of insec

Aplicação da destilação simulada por cromatografia gasosa e da termogravimetria para a avaliação da influência da redução do teor de enxofre sobre as propriedades físico-químicas do óleo diesel

One of the main problems related to the use of diesel as fuel is the presence of sulfur (S) which causes environmental pollution and corrosion of engines. In order to minimize the consequences of the release of this pollutant, Brazilian law established maximum sulfur content that diesel fuel may have. To meet these requirements, diesel with a maximum sulfur concentration equal to 10 mg/kg (S10) has been widely marketed in the country. However, the reduction of sulfur can lead to changes in the physicochemical properties of the fuel, which are essential for the performance of road vehicles. This work aims to identify the main changes in the physicochemical properties of diesel fuel and how they are related to reduction of sulfur content. Samples of diesel types S10, S500 and S1800 were tested according with the methods of the American Society for Testing and Materials (ASTM). The fuels were also characterized by thermogravimetric analysis (TG) and subjected to physical distillation (ASTM D86) and simulated distillation gas chromatography (ASTM D2887). The results showed that the reduction of sulfur turned the fuel lighter and fluid, allowing a greater applicability to low temperature environments and safer for transportation and storage. Through the simulated distillation data was observed that decreasing sulfur content resulted in higher initial boiling point temperatures and the decreasing of the boiling temperature of the medium and heavy fractions. Thermogravimetric analysis showed a loss event mass attributed to volatilization or distillation of light and medium hydrocarbons. Based on these data, the kinetic behavior of the samples was investigated and it was observed that the activation energies (Ea) did not show significant changes throughout conversion. Considering the average of these energies, the S1800 had the highest Ea during the conversion and the S10 the lowest values

Algoritmo papílio como método de proteção de templates para aumentar a segurança em sistemas de identificação biométricos

There are authentication models which use passwords, keys, personal identifiers (cards, tags etc) to authenticate a particular user in the authentication/identification process. However, there are other systems that can use biometric data, such as signature, fingerprint, voice, etc., to authenticate an individual in a system. In another hand, the storage of biometric can bring some risks such as consistency and protection problems for these data. According to this problem, it is necessary to protect these biometric databases to ensure the integrity and reliability of the system. In this case, there are models for security/authentication biometric identification, for example, models and Fuzzy Vault and Fuzzy Commitment systems. Currently, these models are mostly used in the cases for protection of biometric data, but they have fragile elements in the protection process. Therefore, increasing the level of security of these methods through changes in the structure, or even by inserting new layers of protection is one of the goals of this thesis. In other words, this work proposes the simultaneous use of encryption (Encryption Algorithm Papilio) with protection models templates (Fuzzy Vault and Fuzzy Commitment) in identification systems based on biometric. The objective of this work is to improve two aspects in Biometric systems: safety and accuracy. Furthermore, it is necessary to maintain a reasonable level of efficiency of this data through the use of more elaborate classification structures, known as committees. Therefore, we intend to propose a model of a safer biometric identification systems for identification.

Sea organisms as a source of collagen-derived polymers for skin tissue engineering applications

Advanced therapies combating acute and chronic skin wounds are likely to be brought about using our knowledge of regenerative medicine coupled with appropriately tissue engineered skin substitutes. At the present time, there are no models of an artificial skin that completely replicate normal uninjured skin and they are usually accompanied by fibrotic reactions that result in the production of a scar. Natural biopolymers such as collagen have been a lot investigated as potential source of biomaterial for skin replacement in Tissue Engineering. Collagens are the most abundant high molecular weight proteins in both invertebrate and vertebrate organisms, including mammals, and possess mainly a structural role in connective tissues. From this, they have been elected as one of the key biological materials in tissue regeneration approaches, as skin tissue engineering. In addition, industry is constantly searching for new natural sources of collagen and upgraded methodologies for their production. The most common sources are skin and bone from bovine and porcine origin. However, these last carry high risk of bovine spongiform encephalopathy or transmissible spongiform encephalopathy and immunogenic responses. On the other hand, the increase of jellyfish has led us to consider this marine organism as potential collagen source for tissue engineering applications. In the present study, novel form of acid and pepsin soluble collagen were extracted from dried Rhopilema hispidum jellyfish species in an effort to obtain an alternative and safer collagen. We studied different methods of collagen purification (tissues and experimental procedures). The best collagen yield was obtained using pepsin extraction method (34.16 mg collagen/g of tissue). The isolated collagen was characterized by SDS-polyacrylamide gel electrophoresis and circular dichroism spectroscopy.