Uranyl-Tc(VII)/Tc(V) hybrid clusters.

Pertechnetate (TcO), reduced Tc, and actinides co-exist in spent nuclear fuel and legacy wastes. They co-transport in fuel reprocessing and waste disposal scenarios, necessitating an understanding of co-speciation. Here, we report five new molecular cluster/framework structures with pentameric and tetrameric uranyl building units decorated by TcO/ReO oxoanions, or fused with the reduced technetyl cation Tc(V)O.

Plutonium and Cerium Perrhenate/Pertechnetate Coordination Polymers and Frameworks.

Spent nuclear fuel (SNF) contains transuranic and lanthanide species, which are sometimes recovered and repurposed. One particularly problematic fission product, TcO, hampers this recovery via coextraction with high valence metals, perhaps by complexation during aqueous reprocessing of SNF. There is limited molecular-level knowledge concerning the coordination chemistry between TcO or its well-known surrogate ReO and transuranic/lanthanide species.

Pertechnetate/perrhenate-capped Zr/Hf-Dihydroxide Dimers: Elucidating Zr-TcO Co-Mobility in the Nuclear Fuel Cycle.

Spent nuclear fuel contains heavy element fission products that must be separated for effective reprocessing for a safe and sustainable nuclear fuel cycle. Zr and Tc are high-yield fission products that co-transport in liquid-liquid extraction processes. Here we seek atomic-level information of this co-extraction process, as well as fundamental knowledge about Zr (and Hf ) aqueous speciation in the presence of topology-directing ligands such as pertechnetate (TcO ) and non-radioactive surrogate perrhenate (ReO ).

Synthesis and Characterization of Cerium-Oxo Clusters Capped by Acetylacetonate.

Cerium-oxo clusters have applications in fields ranging from catalysis to electronics and also hold the potential to inform on aspects of actinide chemistry. Toward this end, a cerium-acetylacetonate (acac) monomeric molecule, Ce(acac) (), and two acac-decorated cerium-oxo clusters, [CeO(acac)(CHO)(CHOH)]·10.5MeOH () and [CeO(OH)(acac)(CHCOO)]·6(CHCN) (), were prepared and structurally characterized.

Elucidating Actinide-Pertechnetate and Actinide-Perrhenate Bonding via a Family of Th-TcO and Th-ReO Frameworks and Solutions.

Technetium-99, a β-emitter produced from U fission, poses a challenge for the nuclear industry due to co-extraction of pertechnetate (TcO) with the actinides (An) during nuclear fuel reprocessing. Previous studies suggested that direct coordination of pertechnetate with An plays an important role in the coextraction process. However, few studies have provided direct evidence for An-TcO bonding in the solid state, and even fewer in solution.

Bismuth Coordination Polymers with Fluorinated Linkers: Aqueous Stability, Bivolatility, and Adsorptive Behavior.

Bismuth metal-organic frameworks and coordination polymers (CP) are challenging to synthesize, given the poor solubility of bismuth precursors and asymmetric and labile ligation of Bi due to its intrinsic lone pair. Here, we synthesize and structurally characterize three Bi-CPs, exploiting a tetrafluoroterephtalate (FBDC) linker to determine the effect of high acidity on these synthesis and coordination challenges. Single-crystal X-ray diffraction characterization showed that pi-pi stacking of linkers directs framework arrangement and generally deters open porosity in the three structures, respectively featuring Bi chains ( ), Bi dimers ( ) linked into chains, and Bi tetramers ( ).

Nanomechanical variability in the early evolution of vertebrate dentition.

Conodonts are an extinct group of primitive jawless vertebrates whose elements represent the earliest examples of a mineralized feeding apparatus in vertebrates. Their relative relationship within vertebrates remains unresolved. As teeth, conodont elements are not homologous with the dentition of vertebrates, but they exhibit similarities in mineralization, growth patterns, and function.

Density functional theory and thermodynamics analysis of MAl Keggin substitution reactions: Insights into ion incorporation and experimental confirmation.

Polyaluminum cations, such as the MAl Keggin, undergo atomic substitutions at the heteroatom site (M), where nanoclusters with M = Al, Ga, and Ge have been experimentally studied. The identity of the heteroatom M has been shown to influence the structural and electronic properties of the nanocluster and the kinetics of ligand exchange reactions. To date, only three ε-analogs have been identified, and there is a need for a predictive model to guide experiment to the discovery of new MAl species.

Formation of Nanoscale [Ge O Al (OH) (H O) ] from Condensation of ϵ-GeAl Keggin Polycations*.

Keggin-type polyaluminum cations belong to a unique class of compounds with their large positive charge, hydroxo bridges, and divergent isomerization/oligomerization. Previous reports indicated that oligomerization of this species can only occur through one isomer (δ), but herein we report the isolation of largest Keggin-type cluster that occurs through self-condensation of four ϵ-isomers ϵ-GeAl to form [Ge O Al (OH) (H O) ] cluster (Ge Al ). The cluster was crystallized and structurally characterized by single-crystal X-ray diffraction (SCXRD) and the elemental composition was confirmed by ICP-MS and SEM-EDS.

Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry.

X-ray diffraction data from Silurian conodonts belonging to various developmental stages of the species demonstrate changes in crystallography and degree of nanocrystallite ordering (mosaicity) in both lamellar crown tissue and white matter. The exclusive use of a single species in this study, combined with systematic testing of each element type at multiple locations, provided insight into microstructural and crystallographic differentiation between element type ( , , ) as well as between juveniles and adults. A relative increase in the unit cell dimensions / ratio of nanocrystallites during growth was apparent in areas demonstrating single-crystal behaviour, but no such relationship was seen in dominantly polycrystalline areas.

Ga Incorporation into Al Keggin Polyoxometalates and the Formation of δ-(GaAl) and (GaAl) Polycations.

Keggin-type polyaluminum species (ε-Al, δ-Al, Al, Al, Al) can form upon partial hydrolysis of Al-bearing solutions and are important species for water purification and contaminant transport. While the structural features for the major Al polyaluminum species have been delineated, much less is known regarding heteroatom substitution and resultant structures other than the previously identified ε-GaAl and ε-GeAl cations. Single-atom substitution within polyaluminum species can change the surface reactivity within water treatment scenarios; thus, it is important to understand heteroatom incorporation within this system.

Particulate matters and gaseous pollutants in indoor environment and Association of ultra-fine particulate matters (PM) with lung function.

Real-time particulate matters (PM, PM, PM, PM, PM, and TSP) with AEROCET 531S (USA), gaseous pollutants (NO and TVOC) with Aeroquel 500 gas sampler (NZ) were measured from the indoor air of houses at four residential locations in Dhaka, Bangladesh. PM samples were collected on quartz filters with a dual channel dust sampler (IPM-FDS 2510, India) for selected trace metal determination from five houses of Dhaka. Respiratory function of the occupants was assessed by using a peak expiratory flow meter (Rossmax PF 120).

CHARACTERIZATION OF BINDING SITES OF CLOPIDOGREL AND INTERFERENCE OF LINOLEIC ACID AT THE BINDING SITE ON BOVINE SERUM ALBUMIN.

Binding of clopidogrel to serum albumin has been characterized in the presence and absence of linoleic acid by equilibrium dialysis method where ranitidine and diazepam were used as specific probes. Our findings suggested two binding sites for clopidogrel: a high affinity site (k₁ = 11.5 x 10⁵ M⁻¹) with low capaci- ty (n₁ = 1.

Chemical characterization of PM collected from a rural coastal island of the Bay of Bengal (Bhola, Bangladesh).

This work focuses on the chemical characterization of fine aerosol particles (PM) collected from a rural remote island of the Bay of Bengal (Bhola, Bangladesh) from April to August, 2013. PM particle-loaded filters were analyzed for organic carbon (OC), elemental carbon (EC), water-soluble ions, and selected saccharides (levoglucosan, mannosan, galactosan, arabitol, and mannitol). The average PM mass was 15.

The antioxidant effect of astaxanthin is higher in young mice than aged: a region specific study on brain.

Astaxanthin is a potential antioxidant which shows neuroprotective property. We aimed to investigate the age-dependent and region-specific antioxidant effects of astaxanthin in mice brain. Animals were divided into 4 groups; treatment young (3 months, n = 6) (AY), treatment old (16 months, n = 6) (AO), placebo young (3 months, n = 6) (PY) and placebo old (16 months, n = 6) (PO) groups.

Interaction of palmitic Acid with metoprolol succinate at the binding sites of bovine serum albumin.

Purpose: The aim of this study was to characterize the binding profile as well as to notify the interaction of palmitic acid with metoprolol succinate at its binding site on albumin.

Methods: The binding of metoprolol succinate to bovine serum albumin (BSA) was studied by equilibrium dialysis method (ED) at 27°C and pH 7.4, in order to have an insight in the binding chemistry of the drug to BSA in presence and absence of palmitic acid.

A cross sectional study on antibiotic resistance pattern of Salmonella typhi clinical isolates from Bangladesh.

Objective: To investigate and compare the resistance and sensitivity of Salmonella typhi samples to commonly used antibiotics in three major divisions of Bangladesh and to evaluate the gradually developing resistance pattern.

Methods: The antibiotic susceptibility of 70 clinical isolates collected from blood, sputum, urine and pus samples were identified by specific antisera and with standard biochemical tests. The patients were divided into 5 age groups.

A systematic review of effectiveness and safety of different regimens of levonorgestrel oral tablets for emergency contraception.

Background: Unintended pregnancy is a complex phenomenon which raise to take an emergency decision. Low contraceptive prevalence and high user failure rates are the leading causes of this unexpected situation. High user failure rates suggest the vital role of emergency contraception to prevent unplanned pregnancy.