‘Languages don’t have bones, so you can just break them’: rethinking multilingualism in education policy and practice in Africa

Multilingualism is widespread amongst individuals and communities in African countries. However, language-in-education policies across the continent continue to privilege monolingual approaches to language use in the classroom. In this paper we highlight the colonial origins of these monolingual ideologies and discuss the detrimental effects which arise when learners’ linguistic repertoires are not welcomed within the education system. We draw attention to major themes within education across a range of contexts: policy vagueness, teachers as policy implementers, and the creation and imposition of boundaries. We advocate for a language-in-education approach which brings the outside in, which welcomes individuals’ lived multilingual realities and which values these as resources for learning. We highlight the ways in which translanguaging could represent a positive shift to the way in which multilingual language practices are talked about, and can contribute to decolonising language policy in African contexts. We conclude by calling to action those working on education and policy to ensure that learners and teachers are better supported. We call ultimately for a rethinking of multilingualism

The kinetics and mechanism of the organo-iridium catalysed racemisation of amines

The dimeric iodo-iridium complex [IrCp*I2 ]2 (Cp*=pentamethylcyclopentadiene) is an efficient catalyst for the racemisation of secondary and tertiary amines at ambient and higher temperatures with a low catalyst loading. The racemisation occurs with pseudo-first-order kinetics and the orresponding four rate constants were obtained by monitoring the time dependence of the concentrations of the (R) and (S) enantiomers starting with either pure (R) or (S) and show a first-order dependence on catalyst concentration. Low temperature 1H NMR data is consistent with the formation of a 1:1 complex with the amine coordinated to the iridium and with both iodide anions still bound to the metal-ion, but at the higher temperatures used for kinetic studies binding is weak and so no saturation zero-order kinetics are observed. A cross-over experiment with isotopically labelled amines demonstrates the intermediate formation of an imine which can dissociate from the iridium complex. Replacing the iodides in the catalyst by other ligands or having an amide substituent in Cp* results in a much less effective catalysts for the racemisation of amines. The rate constants for a deuterated amine yield a significant primary kinetic isotope effect kH/kD = 3.24 ndicating that hydride transfer is involved in the rate-limiting step

Synthesis and Mechanisms of Organo-Iridium Complexes as Catalysts and as Bioactive Agents.

The synthesis of chiral molecules is of great importance to the pharmaceutical, agrochemical, flavour and fragrance industries. The use of organo-iridium complexes has gained a reputation for its great utility in key enantioselective synthetic procedures. Prime examples include the catalytic reduction of carbonyls and imines; iridium-catalysed allylic substitution and catalysed enantioselective hydrogenation of unsaturated carboxylic acids. Important aspects in these processes are the reaction conditions such as the catalyst loading, metal-ion ligands, the substrate, solvent and the reaction times - all of which can affect the degree of enantioselectivity. Understanding the mechanisms of these reactions through kinetic and other studies makes a vital contribution to improving catalytic efficiency. Asymmetric transfer hydrogenation (ATH) is a prime example of a process that offers operational simplicity and has seen a surge in extensive mechanistic investigations encompassing both theoretical and experimental aspects. This work offers new insights into the reaction mechanism of organo-iridium (III) catalysed ATH of imines, particularly that of α-fluorinated imines. The enantioselectivity of ATH has been previously noted to be a result of enantiomer formation following either zero or first-order kinetics. However, for the amine enantiomer formed with zero-order kinetics the consecutive introduction of fluorine α to the C=N bond leads to a decrease in nitrogen basicity, increasing the rate of product release as well as an increase in the electrophilicity of the carbon, facilitating nucleophilic attack. A result of changing the rate limiting step is that the reaction mechanism then proceeds to follow first-order kinetics in the formation of the enantiomeric products, with the almost complete removal of enantioselectivity. The strong electron withdrawing properties of fluorine retard the imine nitrogen’s basicity, consecutive fluorination results in a lowering of the concentration of protonated imine under the reaction conditions, confirming that the iminium ion is the reactive species in this process. An expansion of the work on ATH is offered in the study of the acidity of the carbon acids which act as ligands for iridium. The catalytic species harbours a η6 pentamethylcyclopentadienyl ligand, forming multi-centred bonds to the metal centre; offering both stability, steric protection and significant electron density contribution to the metal centre. In order to estimate the importance of the basicity of this ligand on catalytic activity, the non-aromatic substituted cyclopentadienes were subjected to deuterium exchange, by exposing the Cp* ligand to NaOD in a DMSO-d6/D2O (9:1 v/v %) co-solvent system. The observed pseudo first-order rate constants for H/D exchange are then used to reveal relative acidities of a family of Cp* derivatives. Carboxy tetramethylcyclopentadiene undergoes H/D exchange by intramolecular general base catalysed removal of the acidic proton by the carboxylate anion. Additionally, the synthesis, characterisation and subsequent deuterium exchange experiments of an amido Cp* is discussed, showing sequential 1,5-sigmatropic rearrangements. In an attempt to expand the library of synthetic methodologies for biologically active organo-iridium complexes, a microwave assisted method was developed. The newly furnished complexes feature a variety of Cp* tethered glucose units in an effort to enhance transport and recognition with regards to cell surface interactions. These derivatives were tested for anti-bacterial and anti-cancer activity

Karboxamidem substituovaný tetramethylcyklopentadien - syntéza, charakterizace a jeho iridium(iii) komplexem katalyzovaná redukce iminů

The novel dimeric iodo-iridium(iii) complex, [Ir(Cp*CONMe2)I-2](2), (Cp*CONMe2 = eta(5)-N,N-2,3,4,5-hexamethylcyclopenta-2,4-diene carboxamide) bearing an amide moiety within the tetramethylcyclopentadiene ring, has been synthesised and characterised. The ligand Cp*CONMe2 is synthesised as two regioisomers, however the 2-substituted isomer exists as two distinguishable conformers due to restricted rotation about the amide carbonyl carbon and the ring carbon. The relative acidities of Cp*CONMe2 and Cp* are compared by their relative rates of H/D exchange. The iridium complex of N,N-2,3,4,5-hexamethylcyclopenta-2-4-diene carboxamide [IrCp*CONMe2] and (R,R)-1,2-diphenyl-N '-tosylethane-1,2-diamine ((R,R)-TsDPEN) has been evaluated in the transfer hydrogenation of imines under acidic conditions - a 5 : 2 molar ratio of formic acid : triethylamine as the hydride source for the transfer hydrogenation of 1-methyl-3,4-dihydroisoquinoline (DHIQ) and its 6,7-dimethoxy derivative in acetonitrile. A decreasing enantiomeric excess with reaction progress is attributed to different kinetic orders for formation of the two product amine enantiomers. The pseudo zero-order formation of the R-amine may be due to a pre-steady-state formation of the less stable form of the diastereomeric catalyst. By contrast, both enantiomeric amines from 1-fluorinated methyl DHIQs as substrates for reduction are formed by pseudo first-order processes.Byl připraven a charakterizován nový dimerní jod-iridium(III) komplex, [Ir(Cp*CONMe2)I-2](2), (Cp*CONMe2 = eta(5)-N,N-2,3,4,5-hexamethylcyklopenta-2,4-dien karboxamid) nesoucí amidickou skupinu. Ligand Cp*CONMe2 byl syntetizován jako dva regioizomery, nicméně 2-substutuovaný izomer, v důsledku omezené rotace kolem amidického karbonylového uhlíku a kruhového uhlíku, existuje jako dva rozlišitelné konformery. Relativní acidity Cp*CONMe2 and Cp* jsou porovnávány na základě jejich relativních rychlostí výměny H/D. Iridiový komplex N,N-2,3,4,5-hexamethylcyklopenta-2-4-dienkarboxamid [IrCp*CONMe2] a (R,R)-1,2-difenyl-N '-tosylethan-1,2-diamin ((R,R)-TsDPEN) jsou zdrojem hydridu pro hydrogenace s fázovým přenosem 1-methyl-3,4-dihydroisochynonu (DHIQ) a jeho 6,7-dimethoxy derivátu v acetonitrilu. Snižující se enantiomerní přebytek s postupem reakce je připisován různým kinetickým řádům při tvorbě dvou produktů - aminových enantiomerů. Pseudo-nultého řádu u vzniku R-aminu může být způsoben vznikem méně stabilní formy diastereomerního katalyzátoru před ustáleným stavem. Naproti tomu oba enantiomerní aminy z 1-fluorovaných methyl DHIQ jako substrátů pro redukci jsou tvořeny procesy pseudo prvního řádu

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

Background: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. Methods: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. Results: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. Conclusions: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Medical Research Council of South Africa gran

Maternal and neonatal outcomes after caesarean delivery in the African Surgical Outcomes Study: a 7-day prospective observational cohort study.

BACKGROUND: Maternal and neonatal mortality is high in Africa, but few large, prospective studies have been done to investigate the risk factors associated with these poor maternal and neonatal outcomes. METHODS: A 7-day, international, prospective, observational cohort study was done in patients having caesarean delivery in 183 hospitals across 22 countries in Africa. The inclusion criteria were all consecutive patients (aged ≥18 years) admitted to participating centres having elective and non-elective caesarean delivery during the 7-day study cohort period. To ensure a representative sample, each hospital had to provide data for 90% of the eligible patients during the recruitment week. The primary outcome was in-hospital maternal mortality and complications, which were assessed by local investigators. The study was registered on the South African National Health Research Database, number KZ_2015RP7_22, and on ClinicalTrials.gov, number NCT03044899. FINDINGS: Between February, 2016, and May, 2016, 3792 patients were recruited from hospitals across Africa. 3685 were included in the postoperative complications analysis (107 missing data) and 3684 were included in the maternal mortality analysis (108 missing data). These hospitals had a combined number of specialist surgeons, obstetricians, and anaesthetists totalling 0·7 per 100 000 population (IQR 0·2-2·0). Maternal mortality was 20 (0·5%) of 3684 patients (95% CI 0·3-0·8). Complications occurred in 633 (17·4%) of 3636 mothers (16·2-18·6), which were predominantly severe intraoperative and postoperative bleeding (136 [3·8%] of 3612 mothers). Maternal mortality was independently associated with a preoperative presentation of placenta praevia, placental abruption, ruptured uterus, antepartum haemorrhage (odds ratio 4·47 [95% CI 1·46-13·65]), and perioperative severe obstetric haemorrhage (5·87 [1·99-17·34]) or anaesthesia complications (11·47 (1·20-109·20]). Neonatal mortality was 153 (4·4%) of 3506 infants (95% CI 3·7-5·0). INTERPRETATION: Maternal mortality after caesarean delivery in Africa is 50 times higher than that of high-income countries and is driven by peripartum haemorrhage and anaesthesia complications. Neonatal mortality is double the global average. Early identification and appropriate management of mothers at risk of peripartum haemorrhage might improve maternal and neonatal outcomes in Africa. FUNDING: Medical Research Council of South Africa.Medical Research Council of South Africa