Coordination and lonic compounds of benzamide and related molecules and metal halides

Organic-inorganic hybrid materials of divalent transition metal halides and simple organic molecules are known to exhibit interesting properties, with both the organic and the inorganic metal halide components contributing to the overall properties of the material (Aakeroy, Champness and Janaik, 2010) (Alexandre et al., 2007) (Aruta et al., 2004) (Criado et al., 1999) (Chondroudis and Mitzi, 1999) (Mitzi, Chondroudis and Kagan, 2001) (Robin and Fromm, 2006). The benzamide molecule was chosen as the primary organic component in this study, due to its potential to form aromatic interactions, and the fact that it possesses two potential sites for hydrogen bonding or protonation or coordination, via the amide group. In addition, the 4-aminobenzamide molecule was investigated due to its similarity to the benzamide molecule, except for an additional functional group on the opposite side of the amide group. A range of inorganic, divalent transition metal chlorides and bromides were selected as inorganic components, including CuX2, CdX2, CoX2, MnX2, HgX2 and ZnX2, where X = Cl or Br. Both ionic and neutral coordination type materials can be formed through the combination of the organic components and inorganic components described above, and the outcome of the reaction is controlled by the presence or absence of acid in the reaction medium. In acidic medium protonation of the organic component results in the formation of an ionic material, and in the absence of an acid a neutral coordination material results from the coordination of the organic component to the metal atom of the metal halide component. The stoichiometry and concentration of the acid will also have an influence on the structure as some of the organic ligand may remain unprotonated. In this study seven novel neutral coordination type structures and one ionic material were characterised by single crystal X-ray diffraction. Four isostructural, neutral, one-dimensional coordination polymer structures were observed for the combination of benzamide with CuCl2, CuBr2, CdCl2 and CdBr2 respectively. In this isostructural series the metal ions adopt an octahedral geometry in the case of the Cd analogues, and a tetragonal geometry, due to Jahn-Teller distorsion, for the Cu members of the series. The combination of ZnCl2 with benzamide yielded an isolated, zero-dimensional, neutral coordination compound in which the zinc(II) ion displays a tetrahedral geometry. An octahedral, paddle wheel-type, isolated, zero-dimensional coordination molecule formed from the combination of MnBr2 and benzamide. In all the coordination compounds of benzamide, coordination was found to occur through the oxygen atom of the amide group, while the NH2 group participates in intra- and intermolecular hydrogen bonding interactions. Due to the poor basicity of benzamide, only one ionic compound of this organic component was characterised structurally. In this compound, formed in combination with HgBr2, half of the benzamide molecules are protonated, and a unique, novel, one-dimensional perhalometallate anion was observed in this structure. The combination of 4-aminobenzamide with CoBr2 yielded an isolated, zero-dimensional, neutral coordination structure, in which the cobalt(II) ion adopts an octahedral geometry. The neutral, coordination compound formed between 4-aminobenzamide and CuBr2 has a trigonal bipyramidal geometry, and in addition to the organic and halogeno ligands, aqua ligands are also coordinated to the metal ion in both of the 4-aminobenzamide-containing molecules. Hydrogen bonding and aromatic interactions occur in all of the structures, and these interaction geometries were analysed in detail. It was found that these interactions play an important role in the cohesion of the units in the structure, with exception of the ionic compound of benzamide, which displays strong hydrogen bonding interactions but long aromatic centroid-to-centroid distances. Diffuse reflectance spectroscopy (DRS) was employed to measure the band gaps of the series of isostructural, one-dimensional coordination polymers. These measurements indicated that the Cd analogues in this series have band gaps that place them in the category of electronic insulators. The Cu members of this series were found to be two-band gap materials, with the lower of the two band gaps falling within the conductor range, while the higher band gap falls in the semi-conductor range for the structure containing CuBr2 and benzamide and the structure containing CuCl2 and benzamide. The suitability of Density Functional Theory (DFT) calculations to theoretically calculate the electronic structures and band gap values of the isostructural series of one-dimensional coordination polymers was tested in this study. The plane-wave cut off energy and k-point grid were optimised for the structures, and a range of functionals were tested. The best performing functional was used to calculate the band gap energies, the band structures and the density of states for the four isostructural materials. DFT calculations are known to underestimate band gap energies, and even though the calculated band gaps differ from the experimentally measured band gaps, this difference is smaller than expected. In addition, the DFT calculations were successful in predicting and providing insight into the electronic characteristics of the materials. CopyrightDissertation (MSc)--University of Pretoria, 2012.Chemistryunrestricte

Facial Adiposity, Attractiveness, and Health: A Review

The relationship between facial cues and perceptions of health and attractiveness in others plays an influential role in our social interactions and mating behaviors. Several facial cues have historically been investigated in this regard, with facial adiposity being the newest addition. Evidence is mounting that a robust link exists between facial adiposity and attractiveness, as well as perceived health. Facial adiposity has also been linked to various health outcomes such as cardiovascular disease, respiratory disease, blood pressure, immune function, diabetes, arthritis, oxidative stress, hormones, and mental health. Though recent advances in the analysis of facial morphology has led to significant strides in the description and quantification of facial cues, it is becoming increasingly clear that there is a great deal of nuance in the way that humans use and integrate facial cues to form coherent social or health judgments of others. This paper serves as a review of the current literature on the relationship between facial adiposity, attractiveness, and health. A key component in utilizing facial adiposity as a cue to health and attractiveness perceptions is that people need to be able to estimate body mass from facial cues. To estimate the strength of the relationship between perceived facial adiposity and body mass, a meta-analysis was conducted on studies that quantified the relationship between perceived facial adiposity and BMI/percentage body fat. Summary effect size estimates indicate that participants could reliably estimate BMI from facial cues alone (r = 0.71, n = 458)

Kan die National Credit Act 34 van 2005 deur ooreenkoms tussen die partye van toepassing gemaak word op ’n kredietooreenkoms wat buite die toepassingsgebied van die Wet val?

Kan die National Credit Act 34 van 2005 deur ooreenkoms tussen die partye van toepassing gemaak word op ’n kredietooreenkoms wat buite die toepassingsgebied van die Wet val? Die artikel handel oor die vraag of die National Credit Act 34 van 2005 (die Wet) by wyse van wilsooreenstemming deur die partye tot ’n kredietooreenkoms op hulle ooreenkoms van toepassing gemaak kan word onder omstandighede waar die Wet, volgens die bepalings daarvan, nie op die ooreenkoms van toepassing is nie. Die vraag is tersaaklik in die lig van teenstrydige hofbeslissings in dié verband. Die vraag word ondersoek aan die hand van die toepassing van die Wet op borgooreenkomste, die uitsluiting van sommige regspersoon- verbruikers van die toepassingsveld van die Wet, die doelstellings van die Wet en die belang van laasgenoemde wanneer die Wet uitgelê word, asook ’n opsomming en bespreking van gemelde beslissings. Daar word tot die gevolgtrekking gekom dat die onderhawige vraag bevestigend beantwoord moet word onderhewig daaraan dat daar van die beginsels van inlywing deur inkorporasie gebruik gemaak word.http://www.lexisnexis.co.za2015-05-31hb201

Satellite ligand effects on magnetic exchange in dimers. A structural, magnetic and theoretical investigation of Cu2L2X4 (L = methylisothiazolinone and X = Cl−, Br−)

Halide-bridged polymers have gained significant interest due to their diverse properties and potential applications. Stacked Cu2L2X4 dimers, where L is an organic ligand and X can be Cl− or Br−, are of interest because a chloride analogue where L = 2-pyridone, had previously been reported to exhibit bulk ferromagnetism, which augured great potentiality for this class of compounds. The synthesis, structural characterization, magnetic susceptibility measurements, and computational studies of two isostructural CuClMI (MI = methylisothiazolinone) and CuBrMI polymers of Cu(ii), along with a related CuClPYR (PYR = 2-pyridone) is reported. CuClMI and CuBrMI were found to exhibit AFM bulk properties, due to FM/AFM alternating chains along the halide-bridged polymer axis, while FM bulk properties were confirmed for CuClPYR exhibiting a FM spin ladder. In combination with a benzamide analogue, CuClBA, three O-donor amides, CuClMI, CuClBA and CuClPYR were analyzed and revealed that the kinetic exchange is affected by the identity, but more importantly, the orientation of the satellite ligands. The torsional angle of the ligand with the dimer plane is shown to significantly affect the magnetic exchange in the dimer, and between dimers, explaining the reported FM bulk properties of CuClPYR. This finding is exceedingly important, as it suggests that a spin device can be constructed to flip between singlet/triplet states by manipulating the orientation of the satellite/terminal ligand. © 2023 The Royal Society of Chemistry. This article includes supplementary data, also available for download

Spatially aggregated clusters and scattered smaller loci of elevated malaria vector density and human infection prevalence in urban Dar es Salaam, Tanzania

Background Malaria transmission, primarily mediated by Anopheles gambiae, persists in Dar es Salaam (DSM) despite high coverage with bed nets, mosquito-proofed housing and larviciding. New or improved vector control strategies are required to eliminate malaria from DSM, but these will only succeed if they are delivered to the minority of locations where residual transmission actually persists. Hotspots of spatially clustered locations with elevated malaria infection prevalence or vector densities were, therefore, mapped across the city in an attempt to provide a basis for targeting supplementary interventions. Methods Two phases of a city-wide population-weighted random sample of cross-sectional household surveys of malaria infections were complemented by two matching phases of geographically overlapping, high-resolution, longitudinal vector density surveys; spanning 2010–2013. Spatial autocorrelations were explored using Moran’s I and hotspots were detected using flexible spatial scan statistics. Results Seven hotspots of spatially clustered elevated vector density and eight of malaria infection prevalence were detected over both phases. Only a third of vectors were collected in hotspots in phase 1 (30 %) and phase 2 (33 %). Malaria prevalence hotspots accounted for only half of malaria infections detected in phase 1 (55 %) and phase 2 (47 %). Three quarters (76 % in phase 1 and 74 % in phase 2) of survey locations with detectable vector populations were outside of hotspots. Similarly, more than half of locations with higher infection prevalence (>10 %) occurred outside of hotspots (51 % in phase 1 and 54 % in phase 2). Vector proliferation hazard (exposure to An. gambiae) and malaria infection risk were only very loosely associated with each other (Odds ratio (OR) [95 % Confidence Interval (CI)] = 1.56 [0.89, 1.78], P = 0.52)). Conclusion Many small, scattered loci of local malaria transmission were haphazardly scattered across the city, so interventions targeting only currently identifiable spatially aggregated hotspots will have limited impact. Routine, spatially comprehensive, longitudinal entomological and parasitological surveillance systems, with sufficient sensitivity and spatial resolution to detect these scattered loci, are required to eliminate transmission from this typical African city. Intervention packages targeted to both loci and hotspots of transmission will need to suppress local vector proliferation, treat infected residents and provide vulnerable residents with supplementary protective measures against exposure

Topographic mapping of the interfaces between human and aquatic mosquito habitats to enable barrier targeting of interventions against malaria vectors.

Geophysical topographic metrics of local water accumulation potential are freely available and have long been known as high-resolution predictors of where aquatic habitats for immature mosquitoes are most abundant, resulting in elevated densities of adult malaria vectors and human infection burden. Using existing entomological and epidemiological survey data, here we illustrate how topography can also be used to map out the interfaces between wet, unoccupied valleys and dry, densely populated uplands, where malaria vector densities and infection risk are focally exacerbated. These topographically identifiable geophysical boundaries experience disproportionately high vector densities and malaria transmission risk, because this is where mosquitoes first encounter humans when they search for blood after emerging or ovipositing in the valleys. Geophysical topographic indicators accounted for 67% of variance for vector density but for only 43% for infection prevalence, so they could enable very selective targeting of interventions against the former but not the latter (targeting ratios of 5.7 versus 1.5 to 1, respectively). So, in addition to being useful for targeting larval source management to wet valleys, geophysical topographic indicators may also be used to selectively target adult mosquitoes with insecticidal residual sprays, fencing, vapour emanators or space sprays to barrier areas along their fringes

A successful lifestyle intervention model replicated in diverse clinical settings

Lifestyle interventions can treat metabolic syndrome and prevent type 2 diabetes mellitus, but they remain underutilised in routine practice. In 2010, an LI model was created in a rural primary care practice and spread with few resources to four other rural practices. A retrospective chart review evaluated changes in health indicators in two practice environments by following 372 participants, mainly women (mean age 52 years). Participants had a mean body mass index of 37 kg/m2at baseline and lost an average of 12% of their initial body weight as a result of the intervention. Among participants at the first intervention site for whom cardiometabolic data were available, the prevalence of metabolic syndrome decreased from 58% at baseline to 19% at follow-up. Taken as a whole, our experience suggests that LIs are feasible and deliver meaningful results in routine primary care practice.

RNA chaperone activity of L1 ribosomal proteins: phylogenetic conservation and splicing inhibition

RNA chaperone activity is defined as the ability of proteins to either prevent RNA from misfolding or to open up misfolded RNA conformations. One-third of all large ribosomal subunit proteins from E. coli display this activity, with L1 exhibiting one of the highest activities. Here, we demonstrate via the use of in vitro trans- and cis-splicing assays that the RNA chaperone activity of L1 is conserved in all three domains of life. However, thermophilic archaeal L1 proteins do not display RNA chaperone activity under the experimental conditions tested here. Furthermore, L1 does not exhibit RNA chaperone activity when in complexes with its cognate rRNA or mRNA substrates. The evolutionary conservation of the RNA chaperone activity among L1 proteins suggests a functional requirement during ribosome assembly, at least in bacteria, mesophilic archaea and eukarya. Surprisingly, rather than facilitating catalysis, the thermophilic archaeal L1 protein from Methanococcus jannaschii (MjaL1) completely inhibits splicing of the group I thymidylate synthase intron from phage T4. Mutational analysis of MjaL1 excludes the possibility that the inhibitory effect is due to stronger RNA binding. To our knowledge, MjaL1 is the first example of a protein that inhibits group I intron splicing

Estimating the contribution of key populations towards HIV transmission in South Africa

INTRODUCTION: In generalized epidemic settings, there is insufficient understanding of how the unmet HIV prevention and treatment needs of key populations (KPs), such as female sex workers (FSWs) and men who have sex with men (MSM), contribute to HIV transmission. In such settings, it is typically assumed that HIV transmission is driven by the general population. We estimated the contribution of commercial sex, sex between men, and other heterosexual partnerships to HIV transmission in South Africa (SA). METHODS: We developed the "Key-Pop Model"; a dynamic transmission model of HIV among FSWs, their clients, MSM, and the broader population in SA. The model was parameterized and calibrated using demographic, behavioural and epidemiological data from national household surveys and KP surveys. We estimated the contribution of commercial sex, sex between men and sex among heterosexual partnerships of different sub-groups to HIV transmission over 2010 to 2019. We also estimated the efficiency (HIV infections averted per person-year of intervention) and prevented fraction (% IA) over 10-years from scaling-up ART (to 81% coverage) in different sub-populations from 2020. RESULTS: Sex between FSWs and their paying clients, and between clients with their non-paying partners contributed 6.9% (95% credibility interval 4.5% to 9.3%) and 41.9% (35.1% to 53.2%) of new HIV infections in SA over 2010 to 2019 respectively. Sex between low-risk groups contributed 59.7% (47.6% to 68.5%), sex between men contributed 5.3% (2.3% to 14.1%) and sex between MSM and their female partners contributed 3.7% (1.6% to 9.8%). Going forward, the largest population-level impact on HIV transmission can be achieved from scaling up ART to clients of FSWs (% IA = 18.2% (14.0% to 24.4%) or low-risk individuals (% IA = 20.6% (14.7 to 27.5) over 2020 to 2030), with ART scale-up among KPs being most efficient. CONCLUSIONS: Clients of FSWs play a fundamental role in HIV transmission in SA. Addressing the HIV prevention and treatment needs of KPs in generalized HIV epidemics is central to a comprehensive HIV response

Estimating the Capacity for ART Provision in Tanzania with the Use of Data on Staff Productivity and Patient Losses

BACKGROUND: International targets for access to antiretroviral therapy (ART) have over-estimated the capacity of health systems in low-income countries in Sub-Saharan Africa. The WHO target for number on treatment by end 2005 for Tanzania was 10 times higher than actually achieved. The target of the national Care and Treatment Plan (CTP) was also not reached. We aimed at estimating the capacity for ART provision and created five scenarios for ART production given existing resource limitations. METHODS: A situation analysis including scrutiny of staff factors, such as available data on staff and patient factors including access to ART and patient losses, made us conclude that the lack of clinical staff is the main limiting factor for ART scale-up, assuming that sufficient drugs and supplies are provided by donors. We created a simple formula to estimate the number of patients on ART based on availability and productivity of clinical staff, time needed to initiate vs maintain a patient on ART and patient losses using five different scenarios with varying levels of these parameters. FINDINGS: Our scenario assuming medium productivity (40% higher than that observed in 2002) and medium loss of patients (20% in addition to 15% first-year mortality) coincides with the actual reported number of patients initiated on ART up to 2008, but is considerably below the national CTP target of 90% coverage for 2009, corresponding to 420,000 on ART and 710,000 life-years saved (LY's). Our analysis suggests that a coverage of 40% or 175,000 on treatment and 350,000 LY's saved is more achievable. CONCLUSION: A comparison of our scenario estimations and actual output 2006-2008 indicates that a simple user-friendly dynamic model can estimate the capacity for ART scale-up in resource-poor settings based on identification of a limiting staff factor and information on availability of this staff and patient losses. Thus, it is possible to set more achievable targets