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1.
Cell ; 154(1): 89-102, 2013 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-23810192

RESUMO

Genetically hard-wired neural mechanisms must enforce behavioral reproductive isolation because interspecies courtship is rare even in sexually naïve animals of most species. We find that the chemoreceptor Gr32a inhibits male D. melanogaster from courting diverse fruit fly species. Gr32a recognizes nonvolatile aversive cues present on these reproductively dead-end targets, and activity of Gr32a neurons is necessary and sufficient to inhibit interspecies courtship. Male-specific Fruitless (Fru(M)), a master regulator of courtship, also inhibits interspecies courtship. Gr32a and Fru(M) are not coexpressed, but Fru(M) neurons contact Gr32a neurons, suggesting that these genes influence a shared neural circuit that inhibits interspecies courtship. Gr32a and Fru(M) also suppress within-species intermale courtship, but we show that distinct mechanisms preclude sexual displays toward conspecific males and other species. Although this chemosensory pathway does not inhibit interspecies mating in D. melanogaster females, similar mechanisms appear to inhibit this behavior in many other male drosophilids.


Assuntos
Drosophila melanogaster/fisiologia , Preferência de Acasalamento Animal , Animais , Corte , Drosophila/classificação , Drosophila/genética , Drosophila/fisiologia , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Feminino , Especiação Genética , Masculino , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
2.
Proc Natl Acad Sci U S A ; 120(20): e2304110120, 2023 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-37155891

RESUMO

Clostridioides difficile infection (CDI) is the most lethal of the five CDC urgent public health treats, resulting in 12,800 annual deaths in the United States alone [Antibiotic Resistance Threats in the United States, 2019 (2019), www.cdc.gov/DrugResistance/Biggest-Threats.html]. The high recurrence rate and the inability of antibiotics to treat such infections mandate discovery of new therapeutics. A major challenge with CDI is the production of spores, leading to multiple recurrences of infection in 25% of patients [C. P. Kelly, J. T. LaMont, N. Engl. J. Med. 359, 1932-1940 (2008)], with potentially lethal consequence. Herein, we describe the discovery of an oxadiazole as a bactericidal anti-C. difficile agent that inhibits both cell-wall peptidoglycan biosynthesis and spore germination. We document that the oxadiazole binds to the lytic transglycosylase SleC and the pseudoprotease CspC for prevention of spore germination. SleC degrades the cortex peptidoglycan, a critical step in the initiation of spore germination. CspC senses germinants and cogerminants. Binding to SleC is with higher affinity than that to CspC. Prevention of spore germination breaks the nefarious cycles of CDI recurrence in the face of the antibiotic challenge, which is a primary cause of therapeutic failure. The oxadiazole exhibits efficacy in a mouse model of recurrent CDI and holds promise in clinical treatment of CDI.


Assuntos
Clostridioides difficile , Clostridioides , Animais , Camundongos , Clostridioides/metabolismo , Clostridioides difficile/metabolismo , Peptidoglicano/metabolismo , Esporos Bacterianos/metabolismo , Proteínas de Bactérias/metabolismo
3.
Syst Biol ; 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38421146

RESUMO

Hundreds or thousands of loci are now routinely used in modern phylogenomic studies. Concatenation approaches to tree inference assume that there is a single topology for the entire dataset, but different loci may have different evolutionary histories due to incomplete lineage sorting, introgression, and/or horizontal gene transfer; even single loci may not be treelike due to recombination. To overcome this shortcoming, we introduce an implementation of a multi-tree mixture model that we call MAST. This model extends a prior implementation by Boussau et al. (2009) by allowing users to estimate the weight of each of a set of pre-specified bifurcating trees in a single alignment. The MAST model allows each tree to have its own weight, topology, branch lengths, substitution model, nucleotide or amino acid frequencies, and model of rate heterogeneity across sites. We implemented the MAST model in a maximum-likelihood framework in the popular phylogenetic software, IQ-TREE. Simulations show that we can accurately recover the true model parameters, including branch lengths and tree weights for a given set of tree topologies, under a wide range of biologically realistic scenarios. We also show that we can use standard statistical inference approaches to reject a single-tree model when data are simulated under multiple trees (and vice versa). We applied the MAST model to multiple primate datasets and found that it can recover the signal of incomplete lineage sorting in the Great Apes, as well as the asymmetry in minor trees caused by introgression among several macaque species. When applied to a dataset of four Platyrrhine species for which standard concatenated maximum likelihood and gene tree approaches disagree, we observe that MAST gives the highest weight (i.e. the largest proportion of sites) to the tree also supported by gene tree approaches. These results suggest that the MAST model is able to analyse a concatenated alignment using maximum likelihood, while avoiding some of the biases that come with assuming there is only a single tree. We discuss how the MAST model can be extended in the future.

4.
Lancet ; 401(10371): 131-139, 2023 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-36495882

RESUMO

BACKGROUND: Type 2 circulating vaccine-derived polioviruses (cVDPV2) from Sabin oral poliovirus vaccines (OPVs) are the leading cause of poliomyelitis. A novel type 2 OPV (nOPV2) has been developed to be more genetically stable with similar tolerability and immunogenicity to that of Sabin type 2 vaccines to mitigate the risk of cVDPV2. We aimed to assess these aspects of nOPV2 in poliovirus vaccine-naive newborn infants. METHODS: In this randomised, double-blind, controlled, phase 2 trial we enrolled newborn infants at the Matlab Health Research Centre, Chandpur, Bangladesh. We included infants who were healthy and were a single birth after at least 37 weeks' gestation. Infants were randomly assigned (2:1) to receive either two doses of nOPV2 or placebo, administered at age 0-3 days and at 4 weeks. Exclusion criteria included receipt of rotavirus or any other poliovirus vaccine, any infection or illness at the time of enrolment (vomiting, diarrhoea, or intolerance to liquids), diagnosis or suspicion of any immunodeficiency disorder in the infant or a close family member, or any contraindication for venipuncture. The primary safety outcome was safety and tolerability after one and two doses of nOPV2, given 4 weeks apart in poliovirus vaccine-naive newborn infants and the primary immunogenicity outcome was the seroconversion rate for neutralising antibodies against type 2 poliovirus, measured 28 days after the first and second vaccinations with nOPV2. Study staff recorded solicited and unsolicited adverse events after each dose during daily home visits for 7 days. Poliovirus neutralising antibody responses were measured in sera drawn at birth and at age 4 weeks and 8 weeks. This study is registered on ClinicalTrials.gov, NCT04693286. FINDINGS: Between Sept 21, 2020, and Aug 16, 2021, we screened 334 newborn infants, of whom three (<1%) were found to be ineligible and one (<1%) was withdrawn by the parents; the remaining 330 (99%) infants were assigned to receive nOPV2 (n=220 [67%]) or placebo (n=110 [33%]). nOPV2 was well tolerated; 154 (70%) of 220 newborn infants in the nOPV2 group and 78 (71%) of 110 in the placebo group had solicited adverse events, which were all mild or moderate in severity. Severe unsolicited adverse events in 11 (5%) vaccine recipients and five (5%) placebo recipients were considered unrelated to vaccination. 306 (93%) of 330 infants had seroprotective maternal antibodies against type 2 poliovirus at birth, decreasing to 58 (56%) of 104 in the placebo group at 8 weeks. In the nOPV2 group 196 (90%) of 217 infants seroconverted by week 8 after two doses, when 214 (99%) had seroprotective antibodies. INTERPRETATION: nOPV2 was well tolerated and immunogenic in newborn infants, with two doses, at birth and 4 weeks, resulting in almost 99% of infants having protective neutralising antibodies. FUNDING: Bill & Melinda Gates Foundation.


Assuntos
Poliomielite , Poliovirus , Recém-Nascido , Humanos , Lactente , Pré-Escolar , Bangladesh , Anticorpos Antivirais , Vacina Antipólio Oral , Poliomielite/prevenção & controle , Anticorpos Neutralizantes , Método Duplo-Cego
5.
Chemistry ; : e202401987, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38820179

RESUMO

A new type of diborate clathrochelate (cage) ligand featuring nine inwardly pointing nitrogen donors that form a large, rigid cavity, termed a mausolate, is presented. The cavity size and high denticity make this an attractive delivery vehicle for large radionuclides in nuclear medicine. Metal mausolate complexes are stable to air and water (neutral pH) and display extremely high thermal stability (> 400 0C). Lanthanide uptake by the mausolate ligand occurs rapidly in solution at room temperature and once complexed, the lanthanide ions are not displaced by a 250-fold excess of a competitive lanthanide salt over more than one week.

6.
Inorg Chem ; 63(11): 4819-4827, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38437739

RESUMO

Progress toward the closure of the nuclear fuel cycle can be achieved if satisfactory separation strategies for the chemoselective speciation of the trivalent actinides from the lanthanides are realized in a nonproliferative manner. Since Kolarik's initial report on the utility of bis-1,2,4-triazinyl-2,6-pyridines (BTPs) in 1999, a perfect complexant-based, liquid-liquid separation system has yet to be realized. In this report, a comprehensive performance assessment for the separation of 241Am3+ from 154Eu3+ as a model system for spent nuclear fuel using hydrocarbon-actuated alkoxy-BTP complexants is described. These newly discovered complexants realize gains that contemporary aryl-substituted BTPs have yet to achieve, specifically: long-term stability in highly concentrated nitric acid solutions relevant to the low pH of unprocessed spent nuclear fuel, high DAm over DEu in the economical, nonpolar diluent Exxal-8, and the demonstrated capacity to complete the separation cycle with high efficiency by depositing the chelated An3+ to the aqueous layer via decomplexation of the metal-ligand complex. These soft-N-donor BTPs are hypothesized to function as bipolar complexants, effectively traversing the organic/aqueous interface for effective chelation and bound metal/ligand complex solubility. Complexant design, separation assays, spectroscopic analysis, single-crystal X-ray crystallographic data, and DFT calculations are reported.

7.
Phys Chem Chem Phys ; 26(19): 14448-14455, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38713487

RESUMO

Cobaltcarbonyl-tert-butylacetylene (CCTBA) is a conventional precursor for the selective atomic layer deposition of Co onto silicon surfaces. However, a limited understanding of the deposition mechanism of such cobalt precursors curbs rational improvements on their design for increased efficiency and tuneable selectivity. The impact of using a less reactive internal alkyne instead of a terminal alkyne was investigated using experimental and computational methods. Using electrospray-ionization mass spectrometry, the formation of CCTBA analogs and their gas phase decomposition pathways were studied. Decomposition experiments show very similar decomposition pathways between the two complexes. The internal alkyne dissociates from the Co complex at slightly lower energies than the terminal alkyne, suggesting that an internal alkynyl ligand may be more suited to low temperature ALD. In addition, transition state calculations using the nudged elastic band method confirm an increased reaction barrier between the internal alkyne and the Si-H surface bonds on Si(111). These results suggests that using a less reactive internal alkyne will result in fewer embedded carbon impurities during deposition onto Si wafers. DFT calculations using the PBE functional and periodic boundary conditions also predict increased surface binding with the metal centers of the internal alkynyl complex.

8.
Ann Vasc Surg ; 105: 1-9, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38492727

RESUMO

BACKGROUND: The stroke rate in blunt cerebrovascular injury (BCVI) varies from 25% without treatment to less than 8% with antithrombotic therapy. There is no consensus on the optimal management to prevent stroke BCVI. We investigated the efficacy and safety of oral Aspirin (ASA) 81 mg to prevent BCVI-related stroke compared to historically reported stroke rates with ASA 325 mg and heparin. METHODS: A single-center retrospective study included adult trauma patients who received oral ASA 81 mg for BCVI management between 2013 and 2022. Medical records were reviewed for demographic and injury characteristics, imaging findings, treatment-related complications, and outcomes. RESULTS: Eighty-four patients treated with ASA 81 mg for BCVI were identified. The mean age was 41.50 years, and 61.9% were male. The mean Injury Severity Score and Glasgow Coma Scale were 19.82 and 12.12, respectively. A total of 101 vessel injuries were identified, including vertebral artery injuries in 56.4% and carotid artery injuries in 44.6%. Traumatic brain injury was found in 42.9%, and 16.7% of patients had a solid organ injur. Biffl grade I (52.4%) injury was the most common, followed by grade II (37.6%) and grade III (4.9%). ASA 81 mg was started in the first 24 hours in 67.9% of patients, including 20 patients with traumatic brain injury and 8 with solid organ injuries. BCVI-related stroke occurred in 3 (3.5%) patients with Biffl grade II (n = 2) and III (n = 1). ASA-related complications were not identified in any patient. The mean length of stay in the hospital was 10.94 days, and 8 patients died during hospitalization due to complications of polytrauma. Follow-up with computed tomography angiography was performed in 8 (9.5%) patients, which showed improvement in 5 and a stable lesion in 3 at a mean time of 58 days after discharge. CONCLUSIONS: In the absence of clear guidelines regarding appropriate medication, BCVI management should be individualized case-by-case through a multidisciplinary approach. ASA 81 mg is a viable option for BCVI-related stroke prevention compared to the reported stroke rates (2%-8%) with commonly used antithrombotics like heparin and ASA 325 mg. Future prospective studies are needed to provide insight into the safety and efficacy of the current commonly used agent in managing BCVI.


Assuntos
Aspirina , Traumatismo Cerebrovascular , Inibidores da Agregação Plaquetária , Acidente Vascular Cerebral , Ferimentos não Penetrantes , Humanos , Masculino , Feminino , Estudos Retrospectivos , Resultado do Tratamento , Adulto , Aspirina/efeitos adversos , Aspirina/administração & dosagem , Pessoa de Meia-Idade , Acidente Vascular Cerebral/prevenção & controle , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/diagnóstico , Inibidores da Agregação Plaquetária/efeitos adversos , Inibidores da Agregação Plaquetária/administração & dosagem , Ferimentos não Penetrantes/diagnóstico por imagem , Fatores de Risco , Traumatismo Cerebrovascular/diagnóstico por imagem , Traumatismo Cerebrovascular/complicações , Fatores de Tempo , Administração Oral , Medição de Risco , Adulto Jovem , Idoso
9.
J Couns Psychol ; 71(2): 89-103, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38376929

RESUMO

Every year, millions of Americans do not receive needed mental health (MH) services. Although Pacific Islanders (PI) have a high need for MH services, this group has the lowest rate of MH care help seeking. This is especially concerning as the rate of suicide has been increasing within the PI community. This study explored how Pacific Islanders think about MH supports, including their attitudes toward and perceptions of barriers to receiving MH services. An interpretative phenomenological analysis focus group study was conducted with cross-generational Pacific Islanders residing in one western state. The findings include (a) PI perceptions that MH help seeking results in family burdensomeness, stigma, and shame; (b) negotiating PI social customs and beliefs related to MH help seeking, care, and support; and (c) PI mistrust of institutional resources. These themes seemed to interact with each other and create perpetuate barriers which prevent help-seeking behaviors. Clinical and research implications will be provided. (PsycInfo Database Record (c) 2024 APA, all rights reserved).


Assuntos
Cultura , Serviços de Saúde Mental , Humanos , Bases de Dados Factuais , Vergonha , População das Ilhas do Pacífico
10.
Clin Microbiol Rev ; 35(3): e0021121, 2022 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-35726607

RESUMO

Cholera, caused by Vibrio cholerae, persists in developing countries due to inadequate access to safe water, sanitation, and hygiene. There are approximately 4 million cases and 143,000 deaths each year due to cholera. The disease is transmitted fecally-orally via contaminated food or water. Severe dehydrating cholera can progress to hypovolemic shock due to the rapid loss of fluids and electrolytes, which requires a rapid infusion of intravenous (i.v.) fluids. The case fatality rate exceeds 50% without proper clinical management but can be less than 1% with prompt rehydration and antibiotics. Oral cholera vaccines (OCVs) serve as a major component of an integrated control package during outbreaks or within zones of endemicity. Water, sanitation, and hygiene (WaSH); health education; and prophylactic antibiotic treatment are additional components of the prevention and control of cholera. The World Health Organization (WHO) and the Global Task Force for Cholera Control (GTFCC) have set an ambitious goal of eliminating cholera by 2030 in high-risk areas.


Assuntos
Vacinas contra Cólera , Cólera , Antibacterianos , Cólera/diagnóstico , Cólera/epidemiologia , Cólera/prevenção & controle , Surtos de Doenças/prevenção & controle , Humanos , Água
11.
J Am Chem Soc ; 145(10): 5631-5636, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36856576

RESUMO

Cyclobutadiene is a highly reactive antiaromatic hydrocarbon that has fascinated chemists for over 60 years. However, its preparation and uses in chemical synthesis are sparing, in part due to its lengthy synthesis that generates hazardous byproducts including excess heavy metals. Herein, we report a scalable, metal-free cyclobutadiene reagent, diethyldiazabicyclohexene dicarboxylate, and explore its intermolecular [4 + 2] cycloaddition with various electron-deficient alkenes. We also demonstrate its utility in a three-step synthesis of dipiperamide G and a diverse array of product derivatizations including bromocyclobutadiene.

12.
Annu Rev Genet ; 49: 269-89, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26421509

RESUMO

In the past 50 years, the application of synthetic nitrogen (N) fertilizer to farmland resulted in a dramatic increase in crop yields but with considerable negative impacts on the environment. New solutions are therefore needed to simultaneously increase yields while maintaining, or preferably decreasing, applied N to maximize the nitrogen use efficiency (NUE) of crops. In this review, we outline the definition of NUE, the selection and development of NUE crops, and the factors that interact with NUE. In particular, we emphasize the challenges of developing crop plants with enhanced NUE, using more classical genetic approaches based on utilizing existing allelic variation for NUE traits. The challenges of phenotyping, mapping quantitative trait loci (QTLs), and selecting candidate genes for NUE improvement are described. In addition, we highlight the importance of different factors that lead to changes in the NUE components of nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE).


Assuntos
Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Nitrogênio/metabolismo , Fertilizantes , Variação Genética , Hordeum/genética , Hordeum/metabolismo , Nitrogênio/farmacocinética , Locos de Características Quantitativas , Triticum/genética , Triticum/metabolismo , Zea mays/genética , Zea mays/metabolismo
13.
Chemistry ; 29(47): e202301164, 2023 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-37227412

RESUMO

Plutonium(IV) oxalate hexahydrate (Pu(C2 O4 )2 ⋅ 6 H2 O; PuOx) is an important intermediate in the recovery of plutonium from used nuclear fuel. Its formation by precipitation is well studied, yet its crystal structure remains unknown. Instead, the crystal structure of PuOx is assumed to be isostructural with neptunium(IV) oxalate hexahydrate (Np(C2 O4 )2 ⋅ 6 H2 O; NpOx) and uranium(IV) oxalate hexahydrate (U(C2 O4 )2 ⋅ 6 H2 O; UOx) despite the high degree of unresolved disorder that exists when determining water positions in the crystal structures of the latter two compounds. Such assumptions regarding the isostructural behavior of the actinide elements have been used to predict the structure of PuOx for use in a wide range of studies. Herein, we report the first crystal structures for PuOx and Th(C2 O4 )2 ⋅ 6 H2 O (ThOx). These data, along with new characterization of UOx and NpOx, have resulted in the full determination of the structures and resolution of the disorder around the water molecules. Specifically, we have identified the coordination of two water molecules with each metal center, which necessitates a change in oxalate coordination mode from axial to equatorial that has not been reported in the literature. The results of this work exemplify the need to revisit previous assumptions regarding fundamental actinide chemistry, which are heavily relied upon within the current nuclear field.

14.
Chemistry ; 29(47): e202302206, 2023 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-37605346

RESUMO

Invited for the cover of this issue is the group of Amy Hixon at the University of Notre Dame. The image depicts the newly identified structure of a PuIV oxalate sheet compared to the historically assumed structure. Read the full text of the article at 10.1002/chem.202301164.

15.
J Exp Biol ; 226(18)2023 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-37671530

RESUMO

Previous studies have shown that selection for starvation resistance in Drosophila melanogaster results in delayed eclosion and increased adult fat stores. It is assumed that these traits are caused by the starvation selection pressure, but its mechanism is unknown. We found that our starvation-selected (SS) population stores more fat during larval development and has extended larval development and pupal development time. Developmental checkpoints in the third instar associated with ecdysteroid hormone pulses are increasingly delayed. The delay in the late larval period seen in the SS population is indicative of reduced and delayed ecdysone signaling. An enzyme immunoassay for ecdysteroids (with greatest affinity to the metabolically active 20-hydroxyecdysone and the α-ecdysone precursor) confirmed that the SS population had reduced and delayed hormone production compared with that of fed control (FC) flies. Feeding third instar larvae on food supplemented with α-ecdysone partially rescued the developmental delay and reduced subsequent adult starvation resistance. This work suggests that starvation selection causes reduced and delayed production of ecdysteroids in the larval stage and affects the developmental delay phenotype that contributes to subsequent adult fat storage and starvation resistance.


Assuntos
Ecdisona , Ecdisteroides , Animais , Ecdisona/genética , Drosophila melanogaster/genética , Larva , Fenótipo
16.
Inorg Chem ; 62(31): 12372-12382, 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37478316

RESUMO

Previously reported carbazole-bis(tetrazole) (CzTR) ligands (where R = iPr and CH2-2,4,6-C6H2Me3) were used to synthesize air-stable, six-coordinate, octahedral bis-ligand Fe(II) complexes (CzTR)2Fe. The synthesis and characterization of these complexes using 1H nuclear magnetic resonance (NMR), X-ray crystallography, Mössbauer spectroscopy, and density functional theory (DFT) calculations are reported. Analysis of the magnetic properties revealed that the isopropyl derivative displays thermally induced spin crossover (SCO) over a temperature range of 150-350 K. This transition appears as an abrupt two-step transition in the solid state but simplifies to a smooth one-step transition in solution. The two-step transition in the solid state has been postulated to be due to lattice and solvation effects. In contrast, the slightly bulkier substituted CH2-2,4,6-C6H2Me3 (CH2Mes) Fe complex displays dramatically different magnetic behavior with no SCO and magnetic data suggesting low-spin Fe(II) with a possible TIP contribution. DFT calculations support the postulate that the change in magnetic behavior is primarily due to the nature of the ligand substituents.

17.
Inorg Chem ; 62(25): 9827-9843, 2023 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-37315176

RESUMO

Incorporation of secondary metal ions into heterobimetallic complexes has emerged as an attractive strategy for rational tuning of compounds' properties and reactivity, but direct solution-phase spectroscopic interrogation of tuning effects has received less attention than it deserves. Here, we report the assembly and study of a series of heterobimetallic complexes containing the vanadyl ion, [VO]2+, paired with monovalent cations (Cs+, Rb+, K+, Na+, and Li+) and a divalent cation (Ca2+). These complexes, which can be isolated in pure form or generated in situ from a common monometallic vanadyl-containing precursor, enable experimental spectroscopic and electrochemical quantification of the influence of the incorporated cations on the properties of the vanadyl moiety. The data reveal systematic shifts in the V-O stretching frequency, isotropic hyperfine coupling constant for the vanadium center, and V(V)/V(IV) reduction potential in the complexes. These shifts can be interpreted as charge density effects parametrized through the Lewis acidities of the cations, suggesting broad potential for the vanadyl ion to serve as a spectroscopic probe in multimetallic species.

18.
Inorg Chem ; 62(39): 16131-16148, 2023 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-37721409

RESUMO

The 2,2'-bipyridyl-6,6'-dicarboxylate ligand (bdc) has been shown in prior work to effectively capture the uranyl(VI) ion, UO22+, from aqueous solutions. However, the redox properties of the uranyl complex of this ligand have not been addressed despite the relevance of uranium-centered reduction to the nuclear fuel cycle and the presence of a bipyridyl core in bdc, a motif long recognized for its ability to support redox chemistry. Here, the bdc complex of UO22+ (1-UO2) has been synthetically prepared and isolated under nonaqueous conditions for the study of its reductive chemical and electrochemical behavior. Spectrochemical titration data collected using decamethylcobaltocene (Cp*2Co) as the reductant demonstrate that 1e- reduction of 1-UO2 is accessible, and companion near-infrared and infrared spectroscopic data, along with theoretical findings from density functional theory, provide evidence that supports the accessibility of the U(V) oxidation state. Data obtained for control ruthenium complexes of bdc and related polypyridyl dicarboxylate ligands provide a counterpoint to these findings; ligand-centered reduction of bdc in these control compounds occurs at potentials more negative than those measured for reduction of 1-UO2, further supporting the generation of uranium(V) in 1-UO2. Taken together, these results underscore the usefulness of bdc as a ligand for actinyl ions and suggest that it could be useful for further studies of the reductive activation of these unique species.

19.
Phys Chem Chem Phys ; 25(23): 16048-16059, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37272776

RESUMO

Methyl aldohexopyranosides were 13C-labeled at contiguous carbons, crystallized, and studied by single-crystal X-ray crystallography and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to examine the degree to which density functional theory (DFT) can calculate one-bond 13C-13C spin-coupling constants (1JCC) in saccharides with sufficient accuracy to permit their use in MA'AT analysis, a newly-reported hybrid DFT/NMR method that provides probability distributions of molecular torsion angles in solution (Zhang et al., J. Phys. Chem. B, 2017, 121, 3042-3058; Meredith et al., J. Chem. Inf. Model., 2022, 62, 3135-3141). Experimental 1JCC values in crystalline samples of the doubly 13C-labeled compounds were measured by solid-state 13C NMR and compared to those calculated from five different DFT models: (1) 1JCC values calculated from single structures identical to those observed in crystalline samples by X-ray crystallography (all atom refinement); (2) 1JCC values calculated from the single structures in (1) but after Hirshfeld atom refinement (HAR); (3) 1JCC values calculated from the single structures in (1) after DFT-optimization of hydrogen atoms only; and (4 and 5) 1JCC values calculated in rotamers of torsion angle θ2 (C1-C2-O2-O2H) or ω (C4-C5-C6-O6) from which either specific or generalized parameterized equations were obtained and used to calculate 1JCC values in the specific θ2 or ω rotamers observed in crystalline samples. Good qualitative agreement was observed between calculated 1JCC values and those measured by solid-state 13C NMR regardless of the DFT model, but in no cases were calculated 1JCC values quantitative, differing (over-estimated) on average by 4-5% from experimental values. These findings, and those reported recently from solution NMR studies (Tetrault et al., J. Phys. Chem. B 2022, 126, 9506-9515), indicate that improvements in DFT calculations are needed before calculated 1JCC values can be used directly as reliable constraints in MA'AT analyses of saccharides in solution.

20.
Public Health Nutr ; 26(12): 3147-3161, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37905557

RESUMO

OBJECTIVE: To conduct a systematic review of experimental or quasi-experimental studies that aimed to improve the nutritional status of children under 5 years of age in Ethiopia. DESIGN: Embase, MEDLINE/PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsychINFO, and Academic Search Database were used to locate peer-reviewed studies, and Google Scholar and Open Dissertation were used to locate grey literatures. All searches were conducted between 2000 and November 2022. SETTING: Ethiopia. PARTICIPANTS: Pregnant women and mothers with children aged 0-59 months. RESULTS: Ten cluster randomised controlled trials (RCT), six quasi-experimental studies and two individual RCT were included. Out of the identified eighteen studies, three studies targeted pregnant mothers. Our findings showed that almost two-thirds of published interventions had no impact on childhood stunting and wasting, and more than half had no impact on underweight. Some behaviour change communication (BCC) interventions, food vouchers, micronutrient supplementation and quality protein maize improved stunting. Similarly, BCC and fish oil supplementation showed promise in reducing wasting, while BCC and the provision of quality protein maize reduced underweight. Additionally, water, sanitation and hygiene (WaSH) interventions provided to pregnant mothers and children under 2 years of age were shown to significantly reduce childhood stunting. CONCLUSION: Future childhood nutritional interventions in Ethiopia should consider adopting an integrated approach that combines the positive effects of interdependent systems such as BCC, food supplemental programmes (e.g. boosting protein and micronutrients), health interventions (e.g. strengthening maternal and childcare), WaSH and financial initiatives (e.g. monetary support and income schemes).


Assuntos
Estado Nutricional , Magreza , Criança , Feminino , Gravidez , Humanos , Lactente , Pré-Escolar , Etiópia , Suplementos Nutricionais , Transtornos do Crescimento
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