18,089 research outputs found
Catalytic reduction of N 2 O with CH 4 and C 3 H 6 over Ag-Rh/Al 2 O 3 bimetallic catalyst in the presence of oxygen
No full textAbstract: A study of nitrous oxide (N 2 O) reduction with methane (CH 4 ) and propene (C 3 H 6 ) in the presence of oxygen (5%) over Ag/Al 2 O 3 , Rh/Al 2 O 3 and Ag-Rh/Al 2 O 3 catalysts, with Ag and Rh loadings of 5 wt% and 0.05 wt% respectively, has been performed. From the results, it was observed that the Ag-Rh bimetallic catalyst was the most active for both nitrous oxide removal (more than 95%) and hydrocarbon oxidation. This high activity seems to be connected with a synergistic effect between Ag and Rh. The findings from X-ray diffraction and X-ray photoelectron spectroscopy studies showed also, that there were no strong interactions (eg alloying) between Ag and Rh
Genetic Analysis of ABO and Rh Blood Groups in Brahmin Population of Uttar Pradesh, India”
No full textA series of glycoprotein and glycolipids on the red blood cell surface constitute blood group antigens. These are A, B, AB and O in ABO blood group system and Rh in rhesus blood group system. These antigens are genetically controlled. Certain diseases have been shown to be associated with certain blood groups. In the present study an attempt is made to study the distribution of ABO and Rh. (D) blood group systems among the Brahmin caste population of Uttar Pradesh State. A total of 200 unrelated Brahmin individuals from Uttar Pradesh were studied for the phenotype and allele frequency distribution of ABO and Rh (D) blood groups. The order of occurrence of ABO phenotypes is B>O>A>AB. The corresponding allele frequencies of O, A, and B alleles are found to be 0.5790, 0.1510 and 0.2697 respectively. The allele frequency of D (0.735) is more than d (0.265). The present study was compared with the other studies reported to understand the affinity between them
A new chapter in Rh research: Rh proteins are ammonium transporters
No full textOccasionally, an original research paper has an unusually significant impact on a particular research field. Such a paper, published recently in Nature Genetics, describes the uncovering of the functional role of the Rh protein family - the proteins that express the Rh blood group antigens. Marini et al.1 demonstrate how two human Rh glycoproteins can correct ammonium transport deficiency in mutant yeast cells. Rh proteins are therefore ammonium transporters - a role that, in vertebrates, has remained previously uncharacterized. These data herald a new era in Rh protein research, beyond their role as blood group antigens, and into the characterization of ammonium transport mechanisms, notably in the kidney
Bifunctional Rh/Al-SBA-15 catalysed cascade hydroformylation and hydroxyalkylation of alkenes to fuel precursors
No full textDecarbonisation of hard-to-abate liquid transport fuels, notably used in the aviation and shipping sectors, requires new catalytic routes to valorise waste feedstocks. Here we report a bifunctional Rh/Al-SBA-15 catalyst for the one-pot, two step cascade hydroformylation of 1-alkenes with CO/H2 to form linear and branched aldehydes, and their subsequent hydroxyalkylation (HAA) with 2-methylfuran to form oxygenated jet fuel precursors. A strong synergy between Rh and Al-SBA-15 is observed for hydroformylation, with the bifunctional catalyst significantly more active than Rh/SBA-15 for the first step of the cascade. Superior yields of desired HAA products are observed over Rh/Al-SBA-15 relative to a physical mixture of Rh/SBA-15 and Al-SBA-15. Under syngas (CO/H2) at 30 bar and 80 °C, alkenes undergo Rh catalysed hydroformylation to aldehydes, and in a subsequent step under N2, HAA of aldehydes over the solid acid sites of Al-SBA-15 gives an overall ∼60% yield of fuel range precursors.Full Tex
Dinuclear Influence on the Mechanism, Reactivity, and Selectivity During Rh-Al Catalyzed Aryl Ether C-O Bond Reduction/Defunctionalization
No full textDinuclear metal complexes with a direct metal-metal interaction have the potential for unique mechanisms, intermediates, and selectivity during catalysis. Here we report density functional theory (DFT) calculations that directly evaluate the influence of a dinuclear metal-metal interaction during aryl C−O bond reduction/defunctionalization with either hydrosilane or bis(pinacolato)diboron (B2(pin)2) reagents catalyzed by a heterodinuclear Rh−Al complex. Our calculations demonstrate the critical Rh−Al cooperative behavior necessary for aryl C−O bond activation and catalytic turnover. However, only the Rh metal center is involved in hydrosilane Si−H bond activation to generate a defunctionalized arene or B−B bond activation of B2(pin)2 to form an aryl bornic acid pinacol ester. The calculations also reveal an unanticipated very strong ligand-to-substrate steric effect that controls reduction site selectivity
Gene Frequencies of ABO and Rh(D) Blood Group Alleles in Five Yemeni Provinces
No full textThis study aims to determine the distribution pattern and gene frequency of the ABO and Rh(D) blood groups in five Yemeni Provinces and compare it with other studies in the world. Methods: The study comprises a total of 1113 healthy blood donors donating in blood banks, Hospitals, primary health centers situated in five Yemeni Provinces, namely Abyan, Al Jawf, Al Hudaydah, Amran and Lahij. ABO and Rh(D) blood groups were determined by standard methods. Calculations for allelic frequency were based on Hardy Weinberg equilibrium. Results: The O blood group was highly distributed: (78.79% (0.88714), 64.62% (0.80177), 63.73% (0.79895) and 60.4% (0.7773) in Al Jawf, Lahij, Al Hudaydah and Abyan, respectively). However, the lowest frequency 53.58% (0.73326) was in Amran, followed by the A blood group which was higher in Amran 34.25% (0.26375). The lowest frequency was in Al Jawf 23.05% (0.08358). The B blood group was highly distributed 10.29% (0.0640) in Abyan and the lowest frequency 5.07 % (0.02846) was in Al Jawf. The AB blood group had also a low frequency. The Rh-positive blood group frequencies were 96.32% O>A>B>AB, and O> A>B among Rh negative donors. Al Jawf Province population had a phenotypic distribution of the Rh-positive blood group of 95.93%. The Rh(D) and d allelic frequency was found to be 0.79826. Abyan, Al Hudaydah, Lahij and Amran had Phenotypic distribution and allelic frequencies of the Rh-positive blood group of 95.35% (0.74213), 94.58% (0.76719), 93.47% (0.74446) and 91.58% (0.70054) respectively. Conclusion: The frequency of ABO blood groups in both Rh positive and negative subjects among the five Yemeni Provinces was O>A>B>AB
Barriers to sustaining antiretroviral treatment in Kisesa, Tanzania: a follow-up study to understand attrition from the antiretroviral program.
No full textTwo years after the introduction of free antiretroviral therapy (ART) in Tanzania and in spite of the logistical support provided to facilitate clinic attendance, a considerable level of attrition from the program was identified among clients from a semi-rural ward. Qualitative research on ART patients' health-seeking behavior identified factors affecting sustained attendance at treatment clinics. A mix of methods was used for data collection including semi-structured interviews with 42 clients and 11 service providers and 4 participatory group activities conducted with members of a post-test group between October and December 2006. A socio-ecological framework guided data analysis to categorize facilitators and barriers into individual, social, programmatic, and structural level influences, and subsequently explored their interaction and relative significance in shaping ART clients' behavior. Our findings suggest that personal motivation and self-efficacy contribute to program retention, and are affected by other individual-level experiences such as perceived health benefits or disease severity. However, these determinants are influenced by others' opinions and beliefs in the community, and constrained by programmatic and structural barriers. Individuals can develop the requisite willingness to sustain strict treatment requirements in a challenging context, but are more likely to do so within supportive family and community environments. Effectiveness and sustainability of ART roll-out could be strengthened by strategic intervention at different levels, with particular attention to community-level factors such as social networks' influence and support
Computational Exploration of Rh-III/Rh-V and Rh-III/Rh-I Catalysis in Rhodium(III)-Catalyzed C-H Activation Reactions of N-Phenoxyacetamides with Alkynes
No full textThe selective rhodium-catalyzed functionalization of arenes is greatly facilitated by oxidizing directing groups that, act both as directing groups and internal oxidants. We report density functional theory (B3LYP and M06) investigations on the mechanism of rhodium(III)-catalyzed redox coupling reaction of N-phenoxyacetamides with alkynes. The results elucidated the role of the internal oxidizing directing group, and the role of Rh-III/Rh-I and Rh-III/Rh-V catalysis of C-H functionalizations. A novel Rh-III/Rh-V-Rh-III cycle successfully rationalizes recent experimental observations by Liu and Lu et al. (Liu, G. Angew. Chem. Int. Ed. 2013, 52, 6033) on the reactions of N-phenoxyacetamides with alkynes in different solvents. Natural Bond Orbital (NBO) analysis confirms the identity of Rhy intermediate in the catalytic cycle.National Natural Science Foundation of China [21133002, 21203004]; Shenzhen Peacock Program [KQTD201103]; National Science Foundation of the USA [CHE-1361104]; National Science Foundation under the CCI Center for Selective C-H Functionalization [CHE-1205646]; National Science Foundation [OCI-1053575]SCI(E)[email protected]; [email protected]
Identificación del fenotipo RH-HR en parejas que acuden a la unidad de fertilidad y esterilidad Clínica Concebir en Quito, 2013
No full textIntroducción.- El estudio de la variabilidad fenotípica del sistema Rh ha permitido establecer los principales fenotipos existentes en la población de estudio así como la probabilidad de producirse una incompatibilidad materno-fetal, sin embargo el antígeno estudiado por mucho tiempo fue el D y sus variantes. Las diferentes patologías como la enfermedad hemolítica del recién nacido, las reacciones de hipersensibilidad en transfusiones sanguíneas y las anemias hemolíticas autoinmunes, han despertado un gran interés en los diferentes grupos sanguíneos, en especial los más inmunogénicos. Actualmente se han reportado inmunizaciones ocasionadas por el resto de antígenos denominados CE/ce, diferentes entre el padre y la madre. Este estudio tuvo el objetivo de determinar la probabilidad de que se presente un riesgo de inmunización fetal mediante la identificación del fenotipo Rh-Hr en parejas. Materiales y Métodos.- Es un estudio descriptivo, de corte transversal que se buscó determinar la frecuencia de fenotipos Rh en un grupo característico donde se analizaron 192 parejas (384 personas) que acudieron a la Unidad de Fertilidad y Esterilidad Clínica Concebir en Quito, durante el año 2013. De las cuales se realizó tipificación sanguínea para el sistema ABO, la identificación del fenotipo Rh, mediante la técnica de aglutinación en tubo y a través del fenotipo determinar los posibles genotipos de cada pareja. Resultados.- Los fenotipos de mayor frecuencia fueron 27.6% CcDee, seguido del 17.97% CcDEe, el 15.89% a ccDee, el 15.62% a CCDee, 9.38% a ccDEe, 5,21% a CcDEE, 4.95% a ccDEE, 2,34 % a CCDEe y 0.78% a ccdee, se estableció que 42 parejas tienen la probabilidad de desarrollo de aloinmunización por la existencia de diferentes antígenos del sistema Rh y de acuerdo a las leyes de herencia Mendeliana el niño heredará un haplotipo paterno diferente al que posee la madre, esta afirmación se corroboró al determinar que las mujeres presentan un fenotipo CcDEe en el 28.12% del total, en comparación al masculino que solo tiene una prevalencia del 7.8%. Conclusiones y Recomendaciones. Los hallazgos encontrados en este estudio alertan a los laboratorios privados y públicos dedicados a la tipificación sanguínea, que se incluya la detección de los fenotipos del Rh especialmente en mujeres sean estas portadoras o no del antígeno D, esto ayudará a alertar sobre la posibilidad de aloinmunización y de esta manera realizar un seguimiento adecuado en un embarazo
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