7,994 research outputs found
Noninvasive prenatal diagnosis of fetal RhD status using cell-free fetal DNA in maternal plasma with TaqMan® real-time PCR assay
No full textPrenatal diagnosis is now part of established obstetric practice in many countries.
However, conventional methods of prenatal diagnosis of obtaining fetal tissues for
genetic analysis, including amniocentesis and chorionic villus sampling, are invasive and
constitute a finite risk to the unborn fetus1. At present, it is widely accepted that both
intact fetal cells as well as cell-free fetal DN A are present in the maternal circulation and
can be recovered for non-invasive prenatal genetic diagnosis2,96,97. However, the rarity of
circulating fetal cells has limited the development and practical use of this approach.
Fetal DNA is present in maternal plasma in much higher fractional concentration than
fetal DNA in the cellular fraction of maternal blood. This important feature has made the
robust detection of fetal DNA possible, even without special enrichment procedures.
As a result of these deve lopments, fetal DNA in maternal plasma has been used for the
noninvasive prenatal diagnosis of sex-linked disorders and single gene disorders such as
beta-thalassemia, congenital adrenal hyperplasia and achondroplasia3-5. In addition,
quantitative aberrations of cell-free fetal DNA have also been found in various
pregnancy-associated disorders, including preeclampsia, preterm labor and fetal trisomy
216,7.
Maternal plasma DNA analysis is also useful for the noninvasive prenatal determination
of fetal RhD blood group status in RhD - negative pregnant women8. For the management
of Hemolytic disease of the fetus and newborn (HDFN) a reliable non-invasive approach
to determine fetal RhD genotype would be of great clinical value. RhD genotyping would
also eliminate the routine administration of Rh-immunoglobulin in RhD-negative
patients.
This approach has been shown by many groups to be highly accurate (See Table 1), and
has been introduced as a routine service in several centers in Europa49,53.
In this thesis, the detail protocol of noninvasive detection of fetal RhD status using
TaqManâ real-time polymerase chain reaction (PCR) technique is going to be described
Unveiling the Structure Sensitivity for Direct Conversion of Syngas to C2-Oxygenates with a Multicomponent-Promoted Rh Catalyst
No full textAbstract: Mn and Li promoted Rh catalysts supported on SiO2 with a thin TiO2 layer were synthesized by stepwise incipient wetness impregnation approach. The thin TiO2 layer on the surface of SiO2 was proved to stabilize those small Rh nanoparticles and hinder their agglomeration. The reducibility of Rh on these catalysts depends on Rh particle size as well as the position of manganese oxide, and large Rh nanoparticles with MnO on Rh nanoparticles can be only reduced at an elevated temperature. Catalyst with large Rh particles exhibits a higher CO conversion and higher products selectivity towards long chain hydrocarbons and C2-oxygenates at the expense of decreasing methane formation than a similar catalyst with smaller Rh particles. This was attributed to the synergistic effect of Mn and Li promotion and molar ratio between Rh0 and Rhδ+ sites on the surface of Rh nanoparticles. Moreover, Rh nanoparticles on MnO are proved to be more efficient in promoting hydrogenation of acetaldehyde to ethanol than its counterpart with MnO on Rh nanoparticles. Finally, in order to target high C2-oxygenates selectivity, low reaction temperature together with a low H2/CO ratio in the feed is recommended. Graphic Abstract: [Figure not available: see fulltext.].ChemE/Catalysis EngineeringChemE/O&O groe
QCM Measurements of RH with Nanostructured Carbon-Based Materials: Part 2-Experimental Characterization
No full textIn this series of two papers, the humidity sensing of a carbon nanotube (CNT) network-based material is transduced and studied through quartz crystal microbalance (QCM) measurements. To this aim, quartzes functionalized with different amounts of sensing material were realized, exposed to different humidity levels, and characterized. In this second paper, the experimental results are presented and discussed. The sensing mechanisms are elucidated exploiting the theory presented in the first paper of this series. The presented results show that the investigated material functionalization induces a large response of QCM to humidity in terms of resonant frequency even at low RH levels, with a sensitivity of about 12 Hz/%RH (at RH < 30% and room temperature and 10 ug of deposited SWCNT solution) and an increase in sensitivity in the high RH range typical of nanostructured film. Regarding the response in terms of motional resistance, a large response is obtained only at intermediate and high humidity levels, confirming that condensation of water in the film plays an important role in the sensing mechanism of nanostructured materials
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]
Solvent effects in heterogeneous selective hydrogenation of acetophenone: differences between Rh/C and Rh/Al2O3 catalysts and the superiority of water as a functional solvent
No full textSelective hydrogenation of acetophenone (AP) to 1-phenylethanol (PhE) was investigated over Rh/Al2O3 and Rh/C catalysts in 13 solvents including water and conventional organic solvents. Strong solvent effects on the overall rate of AP conversion were observed in different manners depending on the catalysts used. The conversion obtained is correlated with hydrogen-bond-donation (HBD) capability for Rh/C but with hydrogen-bond-acceptance (HBA) capacity for Rh/Al2O3. The solvent effects should result from interactions between the carbonyl group of AP and the solvent molecules through hydrogen bonding for Rh/C and from those between the solvent molecules and the catalyst surface for Rh/Al2O3 having HBD hydroxyl groups on its surface. Water is the most effective functional solvent in the selective hydrogenation of AP for C and Al2O3-supported Rh catalysts due to its high HBD capability (a) and low HBA capability (beta), respectively. For the hydrogenation with Rh/Al2O3 in water, its large polarity/polarizability index (pi*) may contribute to the high selectivity to PhE
Unusual selective substitution of triply bridging carbonyl ligands for GaCp* in Rh-6(CO)(16). Synthesis and structural characterization of the Rh-6(mu(3)-CO)(4-x)(mu(3)-GaCp*)(x)(CO)(12) clusters, x=1-4
No full textGrachova EV, Jutzi P, Neumann B, Schebaum LO, Stammler H-G, Tunik SP. Unusual selective substitution of triply bridging carbonyl ligands for GaCp* in Rh-6(CO)(16). Synthesis and structural characterization of the Rh-6(mu(3)-CO)(4-x)(mu(3)-GaCp*)(x)(CO)(12) clusters, x=1-4. JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS. 2002;(3):302-304.Reactions of hexanuclear rhodium clusters with GaCp* (Cp* = C5Me5) result in unusual substitution of face bridging CO ligands to give a series of the Rh-6(mu(3)-CO)(4-x) (mu(3)-GaCp*)(x)(CO)(12) substituted derivatives
Adverse effects of potassium on NO<sub>x</sub> reduction over Di-Air catalyst (Rh/La-Ce-Zr)
No full textThe influence of potassium in Rh on a lanthium promoted zirconia stablised ceria (CZ) catalysts was studied toward NOxreduction reactivity and selectivity. The results are compared with a Rh/CZ catalyst. The samples were characterised by N2 adsorption, XRD, SEM, ICP, and H2-TPR. The study highlighted the importance of stored NOx regeneration over potassium in determining the overall performance of the Rh/K/CZ catalyst. The NOx stored over Rh/K/CZ in the previous NO gas stream cannot be regenerated sufficiently during the C3H6 gas stream, and stored NOxgradually decreased from one cycle to the next, resulting in deteriorating performance of Rh/K/CZ. Besides, problem of NOx slip, the formation of both NH3 and N2O (selectivities up to 30% for each side product) were observed by the addition of potassium into the Rh/CZ catalyst system, depending on the reaction conditions applied and the severity of the catalyst deactivation.</p
Functional heterogeneity within rhodamine123(lo) Hoechst33342(lo/sp) primitive hemopoietic stem cells revealed by pyronin Y
No full textObjective. The aim of this study was to determine the function of primitive hematopoietic stem cells (PHSC) at phases G(0) and G(1) of the cell cycle. Materials and Methods. A combination of supravital dyes rhodamine123 (Rh), Hoechst33342 (Ho), and pyronin (PY) was used to isolate the G(0) and G(1) subsets of PHSC. A competitive repopulation assay was used to evaluate their in vivo function. Results. We confirmed that the Rh(lo)Lin(-)Kit(+)Sca-1(+) PHSC were relatively quiescent when compared with the more mature Rh(hi)Lin(-)Kit(+)Sca-1 HSC and Rh(hi)Lin(-)Kit(+)Sca-1(-) progenitors. In addition, cells with Rh(lo)Lin(-)Kit(+)Sca-1(+), Rh(lo)Ho(lo)Lin(-)Sca-1(+), or Rh(lo)Ho(sp)Lin(-)Sca-1(+) phenotypes identified the same cell population. We further subfractionated the Rh(lo)Ho(lo/sp)Lin(-)Sca-1(+) PHSC using PY into PYlo and PYhi subsets. Limiting dilution analysis revealed that the frequency of long-term in vivo competitive repopulating units (CRU) of the (PYRhHolo/sp)-Rh-lo-Ho-lo PHSC was 1 in 10 cells, whereas there was at least a three-fold lower frequency in those isolated at the G(1) phase (PYhi) We found a dose-dependent PY-mediated cytotoxicity that at moderate concentration affected most of the murine hematopoietic compartment but spared the early HSC compartment. Conclusion. Our data confirm that the HSC compartment is hierarchically ordered on the basis of quiescence and further extend this concept to PY-mediated cytotoxicity. PY supravital dye can be used to reveal functional heterogeneity within the (RhHolosp)-Ho-lo PHSC population but is of limited use in dissecting the relatively more mature hematopoietic stem/progenitor cell population. (C) 2001 International Society for Experimental Hematology. Published by Elsevier Science Inc
Rh promoted In2O3 as a highly active catalyst for CO2 hydrogenation to methanol
No full textSynthesis of methanol with high selectivity and productivity through hydrogenation of CO2 is highly attractive. This work uses a Rh doped In2O3 catalyst to achieve a high methanol productivity of 1.0 g(MeOH) h(-1) g(cat)(-1) while maintaining the intrinsic high selectivity of pure In2O3. Rh facilitated the dissociation of H-2 leading to creation of oxygen vacancies over the In2O3 surface. In addition, Rh atoms also participated in the activation of CO2 to produce formate species with a low activation barrier as evidenced by DFT calculation. Rh species were atomically dispersed in the In2O3 matrix and were stable during a long term reaction. Under reaction conditions, the surface Rh atoms were reduced and were stabilized by charge transfer from neighbouring In atoms. Our results show that incorporation of atomic Rh species in In2O3 can lead to high methanol productivity by creation of oxygen vacancies as well as Rh centred active sites for CO2 activation
Expression of Plasmodium falciparum genes involved in erythrocyte invasion varies among isolates cultured directly from patients.
No full textPlasmodium falciparum merozoites invade erythrocytes using a range of alternative ligands that includes erythrocyte binding antigenic proteins (EBAs) and reticulocyte binding protein homologues (Rh). Variation in the expression of some of these genes among culture-adapted parasite lines correlates with the use of different erythrocyte receptors. Here, expression profiles of four Rh genes and eba175 are analysed in a sample of 42 isolates cultured from malaria patients in Kenya. The profiles cluster into distinct groups, largely because of very strong negative correlations between the levels of expression of particular gene pairs (Rh1 versus Rh2b, eba175 versus Rh2b, and eba175 versus Rh4), previously associated with alternative invasion pathways in culture-adapted parasite lines. High levels of eba175 are seen in isolates in expression profile group I, and may be associated with sialic acid-dependent invasion. Groups II and III are, respectively, characterized by high levels of Rh2b and Rh4, and are more likely to be associated with sialic acid-independent invasion
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