X-ray crystal structures of: [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]•2NCC6H4 AND Ba1.5[Fe(C10H13N2O7)][Co(CN)6]•9H2O; two crystallographic challenges

The novel compound, [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4] was synthesized. Crystal structures of [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5 and Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O were determined employing a Rigaku Mercury375R/M CCD (XtaLAB mini) diffractometer with graphite monochromated Mo-Kα radiation. For [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5, the space group was P-421c(#114) with unit cell dimensions: a =11.0169(14)Å, c =21.499(3)Å, V = 2609.4(6)Å3. Each rhodium had approximately octahedral coordination and was bound to another rhodium atom, two nitrogens (trans to each other), two oxygens (trans to each other), and one benzonitrile nitrogen (trans to rhodium). For Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O the space group was: P-1(#2) with unit cell dimensions: a=13.634Å, b=13.768Å, c=17.254Å and α=84.795°, β=87.863°, γ=78.908°, V=3164.5Å3. The iron atom (nearly octahedral) was coordinated to one chelating ligand (derived from ethylenediaminetetraacetic acid) and the nitrogen of a cyanide ligand. The carbon of the cyanide ligand was bound to cobalt (octahedral). Thus, the cyanide ligand serves as a bridge between the two metals

Evaluation Of Earth-Abundant Monometallic And Bimetallic Complexes For Catalytic Water Splitting

The development of affordable water splitting catalysts from Earth-abundant transition metal ions such as Co and Mn is of immense scientific interest. Aiming to develop an efficient water splitting catalyst, a Co(II) complex featuring an asymmetric, pentadentate quinolyl-bispyridine ligand with a phenylenediamine backbone was synthesized and characterized by spectroscopic, spectrometric, and X-ray analysis. The Co ion was selected because of its ability to undergo redox conversions from 3d5 CoIV through 3d8 CoI thereby making it a suitable catalyst that can withstand harsh structural and electronic changes during catalysis. The electrocatalytic water reduction activity of the catalyst at neutral pH gave a turnover frequency (TOF) of 970 moles of H2/h at an overpotential of 0.65 V. Sustained catalytic water reduction over 18 hours gave a TON of 12,100 and (%FE) of 97% suggesting a stable catalyst. Post-catalytic analysis of a grafoil electrode using SEM, EDS and U.V-visible spectroscopy shows no evidence of catalyst degradation or transformation into other species thus confirming the molecular nature of the catalyst. [CoII(LQpy)H2O]ClO4 is active towards water oxidation as well, operating with a %FE of 91% during catalysis in a 0.1 M borate buffer (pH 8.0), and giving a TON of 97, at an applied potential of 1.50 VAg/AgCl. By using a series of experimental methods as well as DFT techniques, we fully isolated and characterized the catalytic oxidized intermediates for [CoII(LQpy)H2O]ClO4, and proposed a ‘water nucleophilic-attack’ (WNA) mechanism of water oxidation where, the highly electrophilic 3d5 [HSCoIV=O] intermediate is attacked by a nucleophilic water molecule thus forming the essential O-O bond and releasing dioxygen. The photocatalytic activity in the presence of [Ru(bpy)3]2+ and ascorbic acid in acetate buffer (pH 4) shows a TON of 295 and TOF of 50 moles of O2/h. Monometallic cobalt complexes have been shown to efficiently catalyze water reduction and therefore, enhanced activity is expected from binuclear analogs of these monometallic catalysts. The close proximity between two Co centers could trigger cooperativity either by facilitating homolytic pathways or by enabling electron transfer between the metallic centers, thus avoiding the formation of a CoIII–H– species. We hypothesize that cooperativity will be dependent on (i) the distance between the Co centers, (ii) the relative topology of the coordination environments, and (iii) the degree of orientation and overlap between redox-active orbitals. We analyzed the catalytic potential of the bimetallic complex [CoII2(L1’)(bpy)2]Cl4, by means of electrochemical, spectroscopic, and computational methods and observed that it effectively reduces H+ to H2 in acetonitrile in the presence of 100 equiv. of acetic acid with a TON of 18 and %F.E of 94 after 3h at –1.6 VAg/AgCl. This observation allows us to propose that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co-Namido-Co environment offered by L1’. Experimental results reveal that the parent [CoIICoII] complex undergoes two successive metal-based 1e– reductions to generate the catalytically active species [CoICoI], and DFT calculations suggest that addition of a proton to one CoI triggers a cooperative 1e– transfer by each of these CoI centers. This 2e– transfer is an alternative route to generate a more reactive [CoII(CoII–H–)] hydride avoiding the CoIII–H– required in monometallic species. This [CoII(CoII–H–)] species then accepts another H+ in order to release H2. The manganese ion, with its broad range of oxidation states and considerable Earth-abundance, is an appropriate choice for the study of electron transfer processes involved in catalytic water oxidation as it has been used as an efficient electron donor in PS II. It has been proposed that incorporation of phenolate moieties into manganese species could lead to catalytic activity as well. We synthesized two manganese complexes, the hexacoordinate [MnIIIL1CH3OH] and the pentacoordinate [MnIIIL2], with pentadentate tris-phenolate ligands H3L1 and H3L2 respectively. Detailed results from the structural, spectroscopic, and electrochemical evaluation of the two Mn complexes suggest that whilst both complexes show ligand-based oxidations favoring formation of a [MnIII/phenoxyl] species, the hexacoordinate analog could form a [MnIV/phenolate] species. This is specifically due to the low energy difference between the frontier orbitals (\u3c5 kcal/mol) of the Mn center, and the redox-active phenolate ligands. This low energy barrier allows electronic interaction between the Mn ion, and the phenolate ligand, causing valence tautomerism through electron transfer. We, therefore, tested the hexacoordinate [MnIIIL1CH3OH] for water oxidation catalysis and observed an overpotential of 0.77 V and TON of 53 in three hours with the catalyst operating at a %F.E. of 85. This study is particularly useful because it provides a basis for ligand design that favors either a radical or a high-valent metal pathway for catalytic water oxidation

Greenhouse gas production and performance of growing pigs fed high wheat millrun diets supplemented with a multi-carbohydrase enzyme

The inclusion of wheat millrun, a low-cost milling co-product, into swine rations is limited by high non-starch polysaccharide (NSP) content. The high NSP content may decrease digestibility and performance and increase fermentation, perhaps leading to increased greenhouse gas (GHG) production. The high NSP content also suggests that carbohydrase enzymes may improve digestibility. This thesis, therefore, evaluated the impact of wheat millrun and enzyme (carbohydrase) supplementation in diets of growing-finishing pigs on the environment (GHG production) and performance of pigs. A partial life cycle analysis (LCA) was performed to assess GHG output when feed production and manure management was considered. A performance study carried out in the first experiment, showed no interactive effects on growth performance and nutrient digestibility when wheat millrun was supplemented with multi-carbohydrase enzymes in diets of growing-finishing pigs. Increasing wheat millrun linearly reduced energy, nitrogen (N) and phosphorus (P) apparent total-tract digestibility (ATTD) and net energy (NE) content whiles enzyme reduced energy digestibility but not N or P ATTD. Overall average daily gain (ADG) and gain to feed ratio (G:F) were reduced, and average daily feed intake (ADFI) was unaffected in pigs fed the wheat millrun diets. Pigs on the enzyme supplemented diets experienced reduced G:F in the first 14 d. Neither wheat millrun nor multi-carbohydrase supplementation affected days to market. In the second experiment, wheat millrun inclusion in swine diets failed to increase GHG (CO2, N2O, CH4) emissions from growing pigs housed in environmental chambers. Multi-carbohydrase supplementation also had no effect on GHG production. There was an increase in CO2 flux and a decrease in CH4 flux in manure gas measurements with time. In the final experiment, data from the Holos model used in an LCA framework indicated that when feed production was considered, feeding pigs up to 30 % wheat millrun inclusion in the diet could result in about a 25 % reduction in GHG emission in terms of global warming potential (GWP). In summary, the results indicate that feeding growing-finishing pigs up to 30 % wheat millrun diets may be beneficial to the farmer and the environment as it reduces GHG emissions when feed production is also considered.

The Structure of Face-To-Face Casual Conversation Among the Akans

The social act of conversation passes through routine procedures before it is achieved. This paper tries to find out the structure of face-to-face casual conversation openings and closings among the Akans. It also seeks to juxtapose the structure of face-to-face conversation to that of telephone conversation as proposed by Coronel-Molina (1998). 20 dyads of natural conversation from the residents of Amamoma are sampled for the study. Recordings of the conversations of residents of the community serve as the corpus for analysis of the study. The study considers the structure of openings in two forms: presence and absence of interlocutors, and that in whichever case we could have greetings and how-are-you sequence. The identification and recognition sequence only occurs in the absence of interlocutors. However, the closing section of conversations are categorized into three: introductory closings – announcing closure and new topic introduction/recapitulation, intermediate closings – future arrangements and transmitted greetings, and final closings – terminal exchanges. Also, even though conversations occur across different modes, that is, face-to-face and telephone, there seem to be some sort of generality and universality in the structures of conversation (especially, openings) that occur through those media

Bimetallic Cooperativity in Proton Reduction with an Amido‐Bridged Cobalt Catalyst

The bimetallic catalyst [CoII2(L1)(bpy)2]ClO4 (1), in which L1 is an [NN′2O2] fused ligand, efficiently reduced H+ to H2 in CH3CN in the presence of 100 equiv of HOAc with a turnover number of 18 and a Faradaic efficiency of 94 % after 3 h of bulk electrolysis at −1.6 V (vs. Ag/AgCl). This observation allowed the proposal that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co−Namido−Co environment offered by L1. Experimental results revealed that the parent [CoIICoII] complex undergoes two successive metal‐based 1 e− reductions to generate the catalytically active species [CoICoI], and DFT calculations suggested that addition of a proton to one CoI triggers a cooperative 1 e− transfer by each of these CoI centers. This 2 e− transfer is an alternative route to generate a more reactive [CoII(CoII−H−)] hydride, thus avoiding the CoIII−H− required in monometallic species. This [CoII(CoII−H−)] species then accepts another H+ to release H2

Assessing hypertension and diabetes knowledge, attitudes and practices among residents in Akatsi South District, Ghana using the KAP questionnaire

ObjectiveLow awareness of hypertension and diabetes is a public health concern in Ghana. Assessing the general population’s behaviour via knowledge, attitude, and practice (KAP) will be invaluable in these diseases, where prevention and control need a lifelong commitment to a healthy lifestyle. Hence, our goal was to assess the behaviour of Akatsi South residents towards the diseases to assist health providers in implementing tailored intervention programs.MethodsThis was a population-based cross-sectional study with 150 adults (18–70 years) from November to December 2021. A semi-structured questionnaire with face-to-face interviews was used to obtain data. All variables in the model had descriptive statistics. The Chi-square (χ2) test was used to examine correlations between variables, and a value of p < 0.05 was considered statistically significant. The factors associated with checking blood sugar levels and blood pressure were determined using binary logistic regression.ResultsThe respondents’ mean age and BMI were 32.40 years (± 12.07) and 24.98 kg/m2 (± 2.36), respectively. Only 46.67% of the respondents frequently monitor their blood pressure and 17.33% their blood glucose (at least once a year). Less than half of those surveyed had a good knowledge of hypertension (42.7%) and diabetes (32.0%), whereas nearly 3/4 had poor attitudes regarding both conditions. A binary logistic regression analysis revealed that having a good attitude toward hypertension (exp B = 2.479, p = 0.036) and diabetes (exp B = 4.547, p = 0.009) were the participants’ strongest predictor of blood pressure and sugar level checks. However, being overweight (exp B = 0.046, p = 0.002,) or obese (exp B = 0.144, p = 0.034) negatively influenced the frequency with which our respondents checked their blood glucose levels.ConclusionIn the study, we found that the population generally has poor knowledge, which affects their behaviour (attitudes and practices) towards the diseases. To enable healthcare practitioners to reduce disease-associated mortality and morbidity in the future, frequent public health education and promotion about the conditions is critical to closing the knowledge gap

Fiabilité d'une représentation " par événements " de la climatologie de vagues et de courants en Afrique de l'Ouest

Accurate estimation of long-term sea conditions is a major issue in design of coastal and offshore structures, coastal zone management or wave energy harvesting. An estimation of long-term sea conditions requires long duration observational data while in West Africa, only a few (3 years) years of observational data are available. To overcome the limits in duration that observations impose, a stochastic approach, event-based representation of sea state data, is proposed to model the wave climate in West Africa. An “event” refers to a wave system (swell or wind sea) evolving over time, that can be observed for a finite, yet significant duration and that can be linked to a single meteorological source phenomenon (e.g. low pressure systems, storms, etc.). Event-based approach provides structures with physical meaning and temporal consistence for the representation of sea states data. The procedure we have used is decomposed into three following steps. First, we have extracted events from a time series of directional spectra. We have then developed a model to represent each event by a reduced number of parameters. In the last step, we have constructed the stochastic events generator which allows for simulation of individual events and for reconstruction of wave climate over durations of arbitrary lengths. Results showed good agreement between reconstructed climate and that of reference and allow to conclude that the stochastic events generator can reliably be used to simulate sea state data in West Africa for a ocean engineering applications.La connaissance de la climatologie des états de mer est primordiale pour le dimensionnement de structures marines, la gestion des zones côtières ou encore la récupération de l’énergie des vagues. L'estimation de la climatologie nécessite de disposer de données d'observation sur une longue durée, ce qui n'est pas le cas de l'Afrique de l'Ouest. Pour dépasser les limites en durée imposées par les observations, nous proposons dans ces travaux une approche stochastique pour estimer une climatologie de vagues en Afrique de l’Ouest, en s’appuyant sur une représentation “par événements” des données d’états de mer. Un “événement” désigne un système de vagues (houle ou mer du vent) en évolution au cours du temps, observable pendant une durée significative et que l’on peut relier à un unique phénomène météorologique source (e.g. dépressions, tempêtes, etc.). La représentation par événements permet de reproduire la cohérence temporelle des systèmes de vagues et de structurer les données d'états de mer avec une base physique. La démarche adoptée peut se décomposer suivant trois étapes. Nous avons d'abord extrait les événements à partir d’une série temporelle de spectres directionnels d’états de mer. Nous avons ensuite développé un modèle pour représenter chacun des événements par un nombre réduit de paramètres. Enfin, nous avons construit un générateur stochastique permettant la simulation d’événements individuels et la reconstitution de climatologies sur des durées de longueurs arbitraires. Les résultats ont montré un bon accord entre la climatologie reconstituée et celle de référence, permettant de conclure que le générateur peut valablement servir à la simulation de données d’états de mer en Afrique de l’Ouest pour les applications en génie océanique

Assessment in the form of met-ocean events of the wave climate in West Africa

La connaissance de la climatologie des états de mer est primordiale pour le dimensionnement de structures marines, la gestion des zones côtières ou encore la récupération de l’énergie des vagues. L'estimation de la climatologie nécessite de disposer de données d'observation sur une longue durée, ce qui n'est pas le cas de l'Afrique de l'Ouest. Pour dépasser les limites en durée imposées par les observations, nous proposons dans ces travaux une approche stochastique pour estimer une climatologie de vagues en Afrique de l’Ouest, en s’appuyant sur une représentation “par événements” des données d’états de mer. Un “événement” désigne un système de vagues (houle ou mer du vent) en évolution au cours du temps, observable pendant une durée significative et que l’on peut relier à un unique phénomène météorologique source (e.g. dépressions, tempêtes, etc.). La représentation par événements permet de reproduire la cohérence temporelle des systèmes de vagues et de structurer les données d'états de mer avec une base physique. La démarche adoptée peut se décomposer suivant trois étapes. Nous avons d'abord extrait les événements à partir d’une série temporelle de spectres directionnels d’états de mer. Nous avons ensuite développé un modèle pour représenter chacun des événements par un nombre réduit de paramètres. Enfin, nous avons construit un générateur stochastique permettant la simulation d’événements individuels et la reconstitution de climatologies sur des durées de longueurs arbitraires. Les résultats ont montré un bon accord entre la climatologie reconstituée et celle de référence, permettant de conclure que le générateur peut valablement servir à la simulation de données d’états de mer en Afrique de l’Ouest pour les applications en génie océanique.Accurate estimation of long-term sea conditions is a major issue in design of coastal and offshore structures, coastal zone management or wave energy harvesting. An estimation of long-term sea conditions requires long duration observational data while in West Africa, only a few (3 years) years of observational data are available. To overcome the limits in duration that observations impose, a stochastic approach, event-based representation of sea state data, is proposed to model the wave climate in West Africa. An “event” refers to a wave system (swell or wind sea) evolving over time, that can be observed for a finite, yet significant duration and that can be linked to a single meteorological source phenomenon (e.g. low pressure systems, storms, etc.). Event-based approach provides structures with physical meaning and temporal consistence for the representation of sea states data. The procedure we have used is decomposed into three following steps. First, we have extracted events from a time series of directional spectra. We have then developed a model to represent each event by a reduced number of parameters. In the last step, we have constructed the stochastic events generator which allows for simulation of individual events and for reconstruction of wave climate over durations of arbitrary lengths. Results showed good agreement between reconstructed climate and that of reference and allow to conclude that the stochastic events generator can reliably be used to simulate sea state data in West Africa for a ocean engineering applications