Mercury Clathration-Driven Phase Transition in a Luminescent Bipyrazolate Metal−Organic Framework: A Multitechnique Investigation

Mercury is one of the most toxic heavy metals. By virtue of its triple bond, the novel ligand 1,2-bis(1H-pyrazol-4- yl)ethyne (H2BPE) was expressly designed and synthesized to devise metal−organic frameworks (MOFs) exhibiting high chemical affinity for mercury. Two MOFs, Zn(BPE) and Zn(BPE)·nDMF [interpenetrated i-Zn and noninterpenetrated ni-Zn·S, respectively; DMF = dimethylformamide], were isolated as microcrystalline powders. While i-Zn is stable in water for at least 15 days, its suspension in HgCl2 aqueous solutions prompts its conversion into HgCl2@ni-Zn. A multitechnique approach allowed us to shed light onto the observed HgCl2-triggered i-Zn-to- HgCl2@ni-Zn transformation at the molecular level. Density functional theory calculations on model systems suggested that HgCl2 interacts via the mercury atom with the carbon−carbon triple bond exclusively in ni-Zn. Powder X-ray diffraction enabled us to quantify the extent of the i-Zn-to-HgCl2@ni-Zn transition in 100−5000 ppm HgCl2 (aq) solutions, while X-ray fluorescence and inductively coupled plasma-mass spectrometry allowed us to demonstrate that HgCl2 is quantitatively sequestered from the aqueous phase. Irradiating at 365 nm, an intense fluorescence is observed at 470 nm for ni-Zn·S, which is partially quenched for i-Zn. This spectral benchmark was exploited to monitor in real time the i-Zn-to-HgCl2@ni-Zn conversion kinetics at different HgCl2 (aq) concentrations. A sizeable fluorescence increase was observed, within a 1 h time lapse, even at a concentration of 5 ppb. Overall, this comprehensive investigation unraveled an intriguing molecular mechanism, featuring the disaggregation of a water-stable MOF in the presence of HgCl2 and the self-assembly of a different crystalline phase around the pollutant, which is sequestered and simultaneously quantified by means of a luminescence change. Such a case study might open the way to new-conception strategies to achieve real-time sensing of mercury-containing pollutants in wastewaters and, eventually, pursue their straightforward and costeffective purification.University of Insubria for partial fundingPrograma Juan de la Cierva Formación (FJC2020-045043-I)MCIN/AEI/10.13039/501100011033European Union NextGenerationEU/PRTR (Grants PID2020- 113608RB-I00 and TED2021-129886B-C41

Nitrogen removal in fixed-bed submerged biofilters without backwashing

The paper reports the findings of four years of pilot-scale research on nitrogen removal in fixed-bed biofilters fed on real raw municipal wastewater. The plant was made of two fixed-bed biofilm reactors in series with an intermediate settling tank from which excess biomass from the first stage was discharged. The first filter was used for carbon removal either with oxygen or nitrates. The second filter was used for nitrification. The average nitrification rate at 20°C was 0.84 gNH 4 + -N m −2 d −1 with 5 mg l −1 dissolved oxygen in the bulk liquid. Temperature dependence was calculated (r n = r n,20° 1,05 T-20 ). The influent organic load strongly affected ammonia oxidation. If the organic loading exceeded 2.5 gCOD m −2 d −1 nitrification rate was reduced by 50%. Denitrification was performed by recycling nitrates back from the second filter and by using sewage itself as carbon source. Denitrification rate showed to be strongly dependent on temperature (r d = r d,20° 1.11 T-20 ) and on the recycle rate. Hydrolysis of the colloidal COD fraction showed a similar dependence on both temperature and recycle rate. Therefore, it has been concluded that the hydrolysis of finely dispersed COD particles can be the limiting step of denitrification in the biofilter when real sewage is used as carbon source

From upper limits to detection : continuous gravitational waves in the advanced detector era

This thesis concerns continuous gravitational wave signals from non-axisymmetric neutron stars and ground-based interferometric detectors. These detectors are currently being upgraded and this thesis explores relevant issues and methods to prepare for the advanced detector era. A study into sensitivity dependence on the addition of a southern hemisphere detector for a targeted continuous wave search is first presented. Next, we study the effect of close and/or high velocity neutron stars on the ability of a blind, all-sky search to make a detection. Initial results from a narrowband search for signals from the Crab Pulsar and a blind hardware injected signal are then presented. Finally, we describe the development and initial implementation of a large-scale mock data challenge designed to test current continuous wave algorithms to explore various issues before we enter the advanced detector era.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Failure to thrive in toddlers with lack of interest in eating and food and their cognitive development during later childhood

Background: Experiencing Failure to Thrive or malnutrition in early years has been associated with children later displaying low Intelligence Quotient (IQ). The current study's aim was to examine whether Failure to Thrive in Toddlers with Lack of Interest in Eating and Food, a subtype of Avoidant/Restrictive Food Intake Disorder as defined by DSM-5, which has also previously been identified as Infantile Anorexia (IA), was associated with poor cognitive development outcomes during later childhood. Methods: The IQs and growth parameter of 30 children (53% female) previously diagnosed and treated for IA at 12 to 42 months of age, were reevaluated at a mean age of 10.0 years (SD = 2.1 years) and compared to 30 matched control children. Children's growth was assessed using Z-scores and their cognitive development was measured using the Wechsler Intelligence Scale for Children-4th Edition. Results: None of the growth parameters were significantly related to IQ. Further, IQ scores of children previously diagnosed with IA and control children were not significantly different. However, the education level of children's fathers had a significantly positive effect on IQ. Conclusions: Our study highlights the disjunction between growth parameters and IQ within our sample. Overall, our findings suggest that the primary target of intervention for these children should be the parent-child conflict around the feeding relationship, rather than a focus on the child's weight itself. Finally, our results confirm the relevance to include fathers in the intervention of these children

Zirconium Metal-Organic Polyhedra with Dual Behavior for Organophosphate Poisoning Treatment

Organophosphate nerve agents and pesticides are extremely toxic compounds because they result in acetylcholinesterase (AChE) inhibition and concomitant nerve system damage. Herein, we report the synthesis, structural characterization, and proof-of-concept utility of zirconium metal-organic polyhedra (Zr-MOPs) for organophosphate poisoning treatment. The results show the formation of robust tetrahedral cages [((n-butylCpZr)3(OH)3O)4L6]Cl6(Zr-MOP-1; L = benzene-1,4-dicarboxylate, n-butylCp = n-butylcyclopentadienyl, Zr-MOP-10, and L = 4,4′-biphenyldicarboxylate) decorated with lipophilic alkyl residues and possessing accessible cavities of ∼9.8 and ∼10.7 Å inner diameters, respectively. These systems are able to both capture the organophosphate model compound diisopropylfluorophosphate (DIFP) and host and release the AChE reactivator drug pralidoxime (2-PAM). The resulting 2-PAM@Zr-MOP-1(0) host-guest assemblies feature a sustained delivery of 2-PAM under simulated biological conditions, with a concomitant reactivation of DIFP-inhibited AChE. Finally, 2-PAM@Zr-MOP systems have been incorporated into biocompatible phosphatidylcholine liposomes with the resulting assemblies being non-neurotoxic, as proven using neuroblastoma cell viability assays

Tuning Carbon Dioxide Adsorption Affinity of Zinc(II) MOFs by Mixing Bis(pyrazolate) Ligands with N-Containing Tags

The four zinc(II) mixed-ligand metal-organic frameworks (MIXMOFs) Zn(BPZ)x(BPZNO2)1-x, Zn(BPZ)x(BPZNH2)1-x, Zn(BPZNO2)x(BPZNH2)1-x, and Zn(BPZ)x(BPZNO2)y(BPZNH2)1-x-y (H2BPZ = 4,4′-bipyrazole; H2BPZNO2 = 3-nitro-4,4′-bipyrazole; H2BPZNH2 = 3-amino-4,4′-bipyrazole) were prepared through solvothermal routes and fully investigated in the solid state. Isoreticular to the end members Zn(BPZ) and Zn(BPZX) (X = NO2, NH2), they are the first examples ever reported of (pyr)azolate MIXMOFs. Their crystal structure is characterized by a three-dimensional open framework with one-dimensional square or rhombic channels decorated by the functional groups. Accurate information about ligand stoichiometric ratio was determined (for the first time on MIXMOFs) through integration of selected ligands skeleton resonances from 13C cross polarized magic angle spinning solid-state NMR spectra collected on the as-synthesized materials. Like other poly(pyrazolate) MOFs, the four MIXMOFs are thermally stable, with decomposition temperatures between 708 and 726 K. As disclosed by N2 adsorption at 77 K, they are micro-mesoporous materials with Brunauer-Emmett-Teller specific surface areas in the range 400-600 m2/g. A comparative study (involving also the single-ligand analogues) of CO2 adsorption capacity, CO2 isosteric heat of adsorption (Qst), and CO2/N2 selectivity in equimolar mixtures at p = 1 bar and T = 298 K cast light on interesting trends, depending on ligand tag nature or ligand stoichiometric ratio. In particular, the amino-decorated compounds show higher Qst values and CO2/N2 selectivity vs the nitro-functionalized analogues; in addition, tag "dilution" [upon passing from Zn(BPZX) to Zn(BPZ)x(BPZX)1-x] increases CO2 adsorption selectivity over N2. The simultaneous presence of amino and nitro groups is not beneficial for CO2 uptake. Among the compounds studied, the best compromise among uptake capacity, Qst, and CO2/N2 selectivity is represented by Zn(BPZ)x(BPZNH2)1-x