49 research outputs found
Conversion of Amides into Esters by the Nickel-Catalyzed Activation of Amide C-N Bonds
The amide function is ubiquitous in natural compounds as
well as in man-made molecules and materials. It is generally
very stable and poorly reactive owing to its resonance-stabilized
C–N group that imparts a planar geometry to amides.
In contrast, carboxylic esters are generally reactive under a
variety of mild conditions; therefore, it is not surprising that
a number of direct methods are available to the chemist for
converting esters into amides (amino-de-alkoxylation reaction)
but very few for achieving the opposite transformation.
Recently, Professors Neil Garg and Ken Houk from the University
of California, Los Angeles (UCLA, USA) reported in Nature
a groundbreaking method for converting amides into esters
with a high degree of efficiency
Malaria-related mortality based on verbal autopsy in an area of low endemicity in a predominantly rural population in Ethiopia
<p>Abstract</p> <p>Background</p> <p>Although malaria is one of the most important causes of death in Ethiopia, measuring the magnitude of malaria-attributed deaths at community level poses a considerable difficulty. Nevertheless, despite its low sensitivity and specificity, verbal autopsy (VA) has been the most important technique to determine malaria-specific cause of death for community-based studies. The present study was undertaken to assess the magnitude of malaria mortality in a predominantly rural population of Ethiopia using VA technique at Butajira Rural Health Programme (BRHP) Demographic Surveillance Site (DSS).</p> <p>Methods</p> <p>A verbal autopsy was carried out for a year from August 2003 to July 2004 for all deaths identified at BRPH-DSS. Two trained physicians independently reviewed each VA questionnaire and indicated the most likely causes of death. Finally, all malaria related deaths were identified and used for analysis.</p> <p>Results</p> <p>A verbal autopsy study was successfully conducted in 325 deaths, of which 42 (13%) were attributed to malaria. The majority of malaria deaths (47.6%) were from the rural lowlands compared to those that occurred in the rural highlands (31%) and urban (21.4%) areas. The proportional mortality attributable to malaria was not statistically significant among the specific age groups and ecological zones. Mortality from malaria was reckoned to be seasonal; 57% occurred during a three-month period at the end of the rainy season between September and November. About 71% of the deceased received some form of treatment before death, while 12 (28.6%) of those who died neither sought care from a traditional healer nor were taken to a conventional health facility before death. Of those who sought treatment, 53.3% were first taken to a private clinic, 40% sought care from public health facilities, and the remaining two (6.7%) received traditional medicine. Only 11.9% of the total malaria-related deaths received some sort of treatment within 24h after the onset of illness.</p> <p>Conclusion</p> <p>The results of this study suggest that malaria plays a considerable role as a cause of death in the study area. Further data on malaria mortality with a relatively large sample size for at least two years will be needed to substantially describe the burden of malaria mortality in the study area.</p
Intimate partner violence against women in western Ethiopia: prevalence, patterns, and associated factors
<p>Abstract</p> <p>Background</p> <p>Intimate partner violence against women is the psychological, physical, and sexual abuse directed to spouses. Globally it is the most pervasive yet underestimated human rights violation. This study was aimed at investigating the prevalence, patterns and associated factors of intimate partner violence against women in Western Ethiopia.</p> <p>Methods</p> <p>A cross-sectional, population based household survey was conducted from January to April, 2011 using standard WHO multi-country study questionnaire. A sample of 1540 ever married/cohabited women aged 15-49 years was randomly selected from urban and rural settings of East Wollega Zone, Western Ethiopia. Data were principally analyzed using logistic regression.</p> <p>Results</p> <p>Lifetime and past 12 months prevalence of intimate partner violence against women showed 76.5% (95% CI: 74.4-78.6%) and 72.5% (95% CI: 70.3-74.7%), respectively. The overlap of psychological, physical, and sexual violence was 56.9%. The patterns of the three forms of violence are similar across the time periods. Rural residents (AOR 0.58, 95% CI 0.34-0.98), literates (AOR 0.65, 95% CI 0.48-0.88), female headed households <b>(</b>AOR 0.46, 95% CI 0.27-0.76) were at decreased likelihood to have lifetime intimate partner violence. Yet, older women were nearly four times (AOR 3.36, 95% CI 1.27-8.89) more likely to report the incident. On the other hand, abduction (AOR 3.71, 95% CI 1.01-13.63), polygamy (AOR 3.79, 95% CI 1.64-0.73), spousal alcoholic consumption (AOR 1.98, 95% CI 1.21-3.22), spousal hostility (AOR 3.96, 95% CI 2.52-6.20), and previous witnesses of parental violence (AOR 2.00, 95% CI 1.54-2.56) were factors associated with an increased likelihood of lifetime intimate partner violence against women.</p> <p>Conclusion</p> <p>In their lifetime, three out of four women experienced at least one incident of intimate partner violence. This needs an urgent attention at all levels of societal hierarchy including policymakers, stakeholders and professionals to alleviate the situation.</p
A Broadly Applicable Strategy for Entry into Homogeneous Nickel(0) Catalysts from Air-Stable Nickel(II) Complexes
A series of air-stable nickel complexes of the form L[subscript 2]Ni(aryl) X (L = monodentate phosphine, X = Cl, Br) and LNi(aryl)X (L = bis-phosphine) have been synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl[subscript 2]·6H[subscript 2]O or NiBr[subscript 2]·3H[subscript 2]O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of these complexes were characterized by single-crystal X-ray diffraction, and an analysis of their structural features is provided. A case study of their use as precatalysts for the nickel-catalyzed carbonyl-ene reaction is presented, showing superior reactivity in comparison to reactions using Ni(cod)[subscript 2]. Furthermore, as the precatalysts are all stable to air, no glovebox or inert-atmosphere techniques are required to make use of these complexes for nickel-catalyzed reactions.National Institute of General Medical Sciences (U.S.) (GM63755)National Science Foundation (U.S.). Graduate Research Fellowshi
Spatio-temporal clustering of mortality in Butajira HDSS, Ethiopia, from 1987 to 2008
Background: Mortality in a population may be clustered in space and time for a variety of reasons, including geography, socio-economics, environment and demographics. Analysing mortality clusters can therefore reveal important insights into patterns and risks of mortality in a particular setting. Objective and design: To investigate the extent of spatio-temporal clustering of mortality in the Butajira District, Ethiopia, from 1987 to 2008. The Health and Demographic Surveillance System (HDSS) dataset recorded 10,696 deaths among 951,842 person-years of observation, with each death located by household, in which population time at risk was also recorded. The surveyed population increased from 28,614 in 1987 to 62,322 in 2008, in an area approximately 25 km in diameter. Spatio-temporal clustering analyses were conducted for overall mortality and by specific age groups, grouping the population into a 0.01° latitude-longitude grid. Results: A number of significantly high- and low-mortality clusters were identified at various times and places. Butajira town was characterised by significantly low mortality throughout the period. A previously documented major mortality crisis in 1998-1999, largely resulting from malaria and diarrhoea, dominated the clustering analysis. Other local high-mortality clusters, appreciably attributable to meningitis, malaria and diarrhoea, occurred in the earlier part of the period. In the later years, a more homogeneous distribution of mortality at lower rates was observed. Conclusions: Mortality was by no means randomly distributed in this community during the period of observation. The clustering analyses revealed a clear epidemiological transition, away from localised infectious epidemics, over a generation.Global Health Action Supplement 1</p
Nickel-Catalyzed Reductive and Borylative Cleavage of Aromatic Carbon–Nitrogen Bonds in N-Aryl Amides and Carbamates
Nickel-Catalyzed Suzuki–Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory
A modern undergraduate organic chemistry
laboratory experiment
involving the Suzuki–Miyaura coupling is reported. Although
Suzuki–Miyaura couplings typically employ palladium catalysts
in environmentally harmful solvents, this experiment features the
use of inexpensive nickel catalysis, in addition to a “green”
alcohol solvent. The experiment employs heterocyclic substrates, which
are important pharmaceutical building blocks. Thus, this laboratory
procedure exposes students to a variety of contemporary topics in
organic chemistry, including transition metal-catalyzed cross-couplings,
green chemistry, and the importance of heterocycles in drug discovery,
none of which are well represented in typical undergraduate organic
chemistry curricula. The experimental protocol uses commercially available
reagents and is useful in both organic and inorganic instructional
laboratories