Correction: A tutorial on asymmetric electrocatalysis.

Correction for 'A tutorial on asymmetric electrocatalysis' by Jonas Rein et al., Chem. Soc. Rev., 2023, https://doi.org/10.1039/D3CS00511A.

A tutorial on asymmetric electrocatalysis.

Electrochemistry has emerged as a powerful means to enable redox transformations in modern chemical synthesis. This tutorial review delves into the unique advantages of electrochemistry in the context of asymmetric catalysis. While electrochemistry has historically been used as a green and mild alternative for established enantioselective transformations, in recent years asymmetric electrocatalysis has been increasingly employed in the discovery of novel asymmetric methodologies based on reaction mechanisms unique to electrochemistry. This tutorial review first provides a brief tutorial introduction to electrosynthesis, then explores case studies on homogenous small molecule asymmetric electrocatalysis. Each case study serves to highlight a key advance in the field, starting with the historic electrification of known asymmetric transformations and culminating with modern methods relying on unique electrochemical mechanistic sequences. Finally, we highlight case studies in the emerging reasearch areas at the interface of asymmetric electrocatalysis with biocatalysis and heterogeneous catalysis.

Copper-Catalyzed Deaminative Difluoromethylation.

The difluoromethyl group (CF2 H) is considered to be a lipophilic and metabolically stable bioisostere of an amino (NH2 ) group. Therefore, methods that can rapidly convert an NH2 group into a CF2 H group would be of great value to medicinal chemistry. We report herein an efficient Cu-catalyzed approach for the conversion of alkyl pyridinium salts, which can be readily synthesized from the corresponding alkyl amines, to their alkyl difluoromethane analogues. This method tolerates a broad range of functional groups and can be applied to the late-stage modification of complex amino-containing pharmaceuticals.

Copper-Catalyzed, Chloroamide-Directed Benzylic C-H Difluoromethylation.

We report herein the first catalytic strategy to harness amidyl radicals derived from N-chloroamides for C-C bond formation, allowing for the discovery of the first catalytic benzylic C-H difluoromethylation. Under copper-catalyzed conditions, a wide variety of N-chlorocarboxamides and N-chlorocarbamates direct selective benzylic C-H difluoromethylation with a nucleophilic difluoromethyl source at room temperature. This scalable protocol exhibits a broad substrate scope and functional group tolerance, enabling late-stage difluoromethylation of bioactive molecules. This copper-catalyzed, chloroamide-directed strategy has also been extended to benzylic C-H pentafluoroethylation and trifluoromethylation. Mechanistic studies on the difluoromethylation reactions support that the reactions involve the formation of benzylic radicals via intramolecular C-H activation, followed by the copper-mediated transfer of difluoromethyl groups to the benzylic radicals.

Copper-Catalyzed Decarboxylative Difluoromethylation.

We report herein a highly efficient Cu-catalyzed protocol for the conversion of aliphatic carboxylic acids to the corresponding difluoromethylated analogues. This robust, operationally simple and scalable protocol tolerates a variety of functional groups and can convert a diverse array of acid-containing complex molecules to the alkyl-CF2H products. Mechanistic studies support the involvement of alkyl radicals.

Modeling the spatial variability in the spread and correlation of childhood malnutrition in Nigeria.

The average nutritional status of children in Nigeria is, just as in most developing countries, still in an alarmingly bad condition. Prior studies have shown that this status relies on a series of different influences and can be measured by three anthropometric variables for stunting, wasting, and underweight. Different regression modeling techniques have been adopted over the years to explain the determinants and spatial clustering. Those indicators, however, show patterns that are not necessarily full filling requirements for ordinary regression models for the mean and are correlated among each other, a fact that has until now been ignored by most studies. Methods to model outcomes in the light of both, the whole distribution of and the correlation between two or more outcomes based on a set of covariates, have lately been developed. The aim of this paper is to make use of those methods to explain the underlying spatial structure in malnutrition in Nigeria. The study brings to limelight the pattern of spread as well as the interwoven relationships among childhood malnutrition indicators that would have otherwise remained unknown in Nigeria.

Hydrochemical characteristics and quality assessment of groundwater from fractured Albian carbonaceous shale aquifers around Enyigba-Ameri, southeastern Nigeria.

Enyigba-Ameri area is known for its Pb-Zn mining activities and the mine water is usually discharged directly into nearby streams and surface runoff. In order to determine the impacts of mining activities on the quality of water in the area and the general hydrochemical characteristics, field measurements and laboratory tests were carried out on water samples collected from the area. Field measurements and laboratory analyses of physicochemical parameters were determined using standard methods. In addition to the multivariate analyses (principal component analysis and cluster analysis) and ANOVA analysis, ionic cross-plots were used to determine the groundwater physicochemical characteristics and geochemical evolution. From the results, it was observed that Pb4+, Zn2+, Fe2 + & 3+, Ca2+, Mg2+, and K+ had a concentration higher than the stipulated guideline values. Three principal components which explained 87.42% of the total dataset were extracted through the data reduction process. Cluster analysis of the hydrochemical data grouped the water samples into three distinct classes. It was observed that the water chemistry is mainly affected by silicate minerals weathering, carbonate weathering, and base ion exchange processes in descending order. ANOVA analysis showed that Zn2+, Fe2 + & 3+, and Mg2+ had mean values that significantly differed from each other based on the sources of the samples. The Wilcox diagram revealed 4 classes of irrigation water types and the irrigation water quality indices showed that the groundwater in the area is not generally suitable for irrigation purposes.

Tuning Gold Nanoparticles with Chelating Ligands for Highly Efficient Electrocatalytic CO2 Reduction.

Capped chelating organic molecules are presented as a design principle for tuning heterogeneous nanoparticles for electrochemical catalysis. Gold nanoparticles (AuNPs) functionalized with a chelating tetradentate porphyrin ligand show a 110-fold enhancement compared to the oleylamine-coated AuNP in current density for electrochemical reduction of CO2 to CO in water at an overpotential of 340 mV with Faradaic efficiencies (FEs) of 93 %. These catalysts also show excellent stability without deactivation (<5 % productivity loss) within 72 hours of electrolysis. DFT calculation results further confirm the chelation effect in stabilizing molecule/NP interface and tailoring catalytic activity. This general approach is thus anticipated to be complementary to current NP catalyst design approaches.

Prioritisation of native legume species for further evaluation as potential forage crops in water-limited agricultural systems in South Africa.

In the face of climate change, identification of forage species suitable for dryland farming under low rainfall conditions in South Africa is needed. Currently, there are only a limited number of forage species suitable for dryland farming under such conditions. The objective of this study was to identify and prioritise native legume species that could potentially be used in dryland farming systems in water-limited agro-ecosystems in South Africa. Using a combination of ecological niche modelling techniques, plant functional traits, and indigenous knowledge, 18 perennial herbaceous or stem-woody legume species were prioritised for further evaluation as potential fodder species within water-limited agricultural areas. These species will be evaluated further for their forage quality and their ability to survive and produce enough biomass under water limitation and poor edaphic conditions.

Biogeographical Patterns of Legume-Nodulating Burkholderia spp.: from African Fynbos to Continental Scales.

UNLABELLED: Rhizobia of the genus Burkholderia have large-scale distribution ranges and are usually associated with South African papilionoid and South American mimosoid legumes, yet little is known about their genetic structuring at either local or global geographic scales. To understand variation at different spatial scales, from individual legumes in the fynbos (South Africa) to a global context, we analyzed chromosomal (16S rRNA, recA) and symbiosis (nifH, nodA, nodC) gene sequences. We showed that the global diversity of nodulation genes is generally grouped according to the South African papilionoid or South American mimosoid subfamilies, whereas chromosomal sequence data were unrelated to biogeography. While nodulation genes are structured on a continental scale, a geographic or host-specific distribution pattern was not detected in the fynbos region. In host range experiments, symbiotic promiscuity of Burkholderia tuberum STM678(T) and B phymatum STM815(T) was discovered in selected fynbos species. Finally, a greenhouse experiment was undertaken to assess the ability of mimosoid (Mimosa pudica) and papilionoid (Dipogon lignosus, Indigofera filifolia, Macroptilium atropurpureum, and Podalyria calyptrata) species to nodulate in South African (fynbos) and Malawian (savanna) soils. While the Burkholderia-philous fynbos legumes (D lignosus, I filifolia, and P calyptrata) nodulated only in their native soils, the invasive neotropical species M pudica did not develop nodules in the African soils. The fynbos soil, notably rich in Burkholderia, seems to retain nodulation genes compatible with the local papilionoid legume flora but is incapable of nodulating mimosoid legumes that have their center of diversity in South America. IMPORTANCE: This study is the most comprehensive phylogenetic assessment of root-nodulating Burkholderia and investigated biogeographic and host-related patterns of the legume-rhizobial symbiosis in the South African fynbos biome, as well as at global scales, including native species from the South American Caatinga and Cerrado biomes. While a global investigation of the rhizobial diversity revealed distinct nodulation and nitrogen fixation genes among South African and South American legumes, regionally distributed species in the Cape region were unrelated to geographic and host factors.

Corrigendum: Eastern Canadian Gastrointestinal Cancer Consensus Conference 2014.

[This corrects the article DOI: 10.3747/co.22.2603.].

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2016.

The annual Eastern Canadian Gastrointestinal Cancer Consensus Conference 2016 was held in Montreal, Quebec, 5-7 February. Experts in radiation oncology, medical oncology, surgical oncology, and infectious diseases involved in the management of patients with gastrointestinal malignancies participated in presentations and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses multiple topics: ■ Follow-up and survivorship of patients with resected colorectal cancer■ Indications for liver metastasectomy■ Treatment of oligometastases by stereotactic body radiation therapy■ Treatment of borderline resectable and unresectable pancreatic cancer■ Transarterial chemoembolization in hepatocellular carcinoma■ Infectious complications of antineoplastic agents.

Eastern Canadian Colorectal Cancer Consensus Conference 2013: emerging therapies in the treatment of pancreatic, rectal, and colorectal cancers.

The annual Eastern Canadian Colorectal Cancer Consensus Conference held in Montreal, Quebec, 17-19 October 2013, marked the 10-year anniversary of this meeting that is attended by leaders in medical, radiation, and surgical oncology. The goal of the attendees is to improve the care of patients affected by gastrointestinal malignancies. Topics discussed during the conference included pancreatic cancer, rectal cancer, and metastatic colorectal cancer.

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2014.

The annual Eastern Canadian Colorectal Cancer Consensus Conference was held in Montreal, Quebec, 23-25 October 2014. Expert radiation, medical, and surgical oncologists and pathologists involved in the management of patients with gastrointestinal malignancies participated in presentations and discussions resulting in consensus statements on such hot topics as management of neuroendocrine tumours, advanced and metastatic pancreatic cancer, and metastatic colorectal cancer.

Exclusive breastfeeding practice in Nigeria: a bayesian stepwise regression analysis.

Despite the importance of breast milk, the prevalence of exclusive breastfeeding (EBF) in Nigeria is far lower than what has been recommended for developing countries. Worse still, the practise has been on downward trend in the country recently. This study was aimed at investigating the determinants and geographical variations of EBF in Nigeria. Any intervention programme would require a good knowledge of factors that enhance the practise. A pooled data set from Nigeria Demographic and Health Survey conducted in 1999, 2003, and 2008 were analyzed using a Bayesian stepwise approach that involves simultaneous selection of variables and smoothing parameters. Further, the approach allows for geographical variations at a highly disaggregated level of states to be investigated. Within a Bayesian context, appropriate priors are assigned on all the parameters and functions. Findings reveal that education of women and their partners, place of delivery, mother's age at birth, and current age of child are associated with increasing prevalence of EBF. However, visits for antenatal care during pregnancy are not associated with EBF in Nigeria. Further, results reveal considerable geographical variations in the practise of EBF. The likelihood of exclusively breastfeeding children are significantly higher in Kwara, Kogi, Osun, and Oyo states but lower in Jigawa, Katsina, and Yobe. Intensive interventions that can lead to improved practise are required in all states in Nigeria. The importance of breastfeeding needs to be emphasized to women during antenatal visits as this can encourage and enhance the practise after delivery.

Modelling geographical variations and determinants of use of modern family planning methods among women of reproductive age in Nigeria.

Summary Understanding the level, trend, geographical variations and determinants of use of modern family planning (FP) plays a major role in designing effective interventions leading to increased usage. This study assessed these characteristics of FP use in Nigeria using data from the 2003, 2005 and 2007 National HIV/AIDS and Reproductive Health Survey, a national population-based household survey. A Bayesian geo-additive procedure was used, which provides flexible modelling of non-linear and spatial effects at a highly disaggregated level of states. The findings reveal considerable geographical variation in the use of modern FP in Nigeria, with a distinct north-south divide. Furthermore, a significant trend in the use of modern FP was evident, with an increase between 2003 and 2005 followed by a decline between 2005 and 2007. The effect of respondent's age was non-linear, and use of modern FP was found to differ significantly between never-married and currently/formerly married respondents. Awareness of FP methods and knowledge of where to get/buy FP services/methods were found to be significantly associated with usage. The findings provide policymakers with tools to prioritize the use of scarce resources for implementing FP and reproductive health interventions.

Eastern Canadian Colorectal Cancer Consensus Conference: standards of care for the treatment of patients with rectal, pancreatic, and gastrointestinal stromal tumours and pancreatic neuroendocrine tumours.

The annual Eastern Canadian Colorectal Cancer Consensus Conference was held in Halifax, Nova Scotia, October 20-22, 2011. Health care professionals involved in the care of patients with colorectal cancer participated in presentation and discussion sessions for the purposes of developing the recommendations presented here. This consensus statement addresses current issues in the management of rectal cancer, including pathology reporting, neoadjuvant systemic and radiation therapy, surgical techniques, and palliative care of rectal cancer patients. Other topics discussed include multidisciplinary cancer conferences, treatment of gastrointestinal stromal tumours and pancreatic neuroendocrine tumours, the use of folfirinox in pancreatic cancer, and treatment of stage ii colon cancer.

Generality-oriented optimization of enantioselective aminoxyl radical catalysis.

Catalytic enantioselective methods that are generally applicable to a broad range of substrates are rare. We report a strategy for the oxidative desymmetrization of meso-diols predicated on a nontraditional catalyst optimization protocol by using a panel of screening substrates rather than a singular model substrate. Critical to this approach was rational modulation of a peptide sequence in the catalyst incorporating a distinct aminoxyl-based active residue. A general catalyst emerged, providing high selectivity in the delivery of enantioenriched lactones across a broad range of diols, while also achieving up to ~100,000 turnovers.

Resonant bend loss in leakage channel fibers.

Leakage channel fibers, designed to suppress higher-order modes, demonstrate resonant power loss at certain critical radii of curvature. Outside the resonance, the power recovers to the levels offset by the usual mechanism of bend-induced loss. Using C2 imaging, we experimentally characterize this anomaly and identify the corresponding physical mechanism as the radiative decay of the fundamental mode mediated by the resonant coupling to a cladding mode.

Determinants of insecticide-treated net ownership and utilization among pregnant women in Nigeria.

BACKGROUND: Malaria during pregnancy is a major public health problem in Nigeria leading to increase in the risk of maternal mortality, low birth weight and infant mortality. This paper is aimed at highlighting key predictors of the ownership of insecticide treated nets (ITNs) and its use among pregnant women in Nigeria. METHODS: A total of 2348 pregnant women were selected by a multi-stage probability sampling technique. Structured interview schedule was used to elicit information on socio-demographic characteristics, ITN ownership, use, knowledge, behaviour and practices. Logistic regression was used to detect predictors of two indicators: ITN ownership, and ITN use in pregnancy among those who owned ITNs. RESULTS: ITN ownership was low; only 28.8% owned ITNs. Key predictors of ITN ownership included women who knew that ITNs prevent malaria (OR = 3.85; p < 0001); and registration at antenatal clinics (OR = 1.34; p = 0.003). The use of ITNs was equally low with only 7.5% of all pregnant women, and 25.7% of all pregnant women who owned ITNs sleeping under a net. The predictors of ITN use in pregnancy among women who owned ITNs (N = 677) identified by logistic regression were: urban residence (OR = 1.87; p = 0.001); knowledge that ITNs prevent malaria (OR = 2.93; p < 0001) and not holding misconceptions about malaria prevention (OR = 1.56; p = 0.036). Educational level was not significantly related to any of the two outcome variables. Although registration at ANC is significantly associated with ownership of a bednet (perhaps through free ITN distribution) this does not translate to significant use of ITNs. CONCLUSIONS: ITN use lagged well behind ITN ownership. This seems to suggest that the current mass distribution of ITNs at antenatal facilities and community levels may not necessarily lead to use unless it is accompanied by behaviour change interventions that address the community level perceptions, misconceptions and positively position ITN as an effective prevention device to prevent malaria.