A follow-up study of 100 reading disability cases, now adults, who were associated with the Boston University Education Clinic between 1936-1948

Thesis (Ed.M.)--Boston Universit

Human peripheral blood mononuclear cells targeted multidimensional switch for selective detection of HSO3− anion

A new ratiometric π-conjugated luminophore with donor-acceptor (D- π- A) network CM {(E)-2-(4-(2-(9-butyl-9H-carbazol-3-yl)vinyl)benzylidine)malononitrile} has been synthesized by malononitrile conjugated carbazole dye with an intervening p-styryl spacer. Here, p-styryl conjugated malononitrile is used as a recognition site for the detection of HSO3− with a fast response time (within 50 s). In a mixed aqueous solution, CM reacts with HSO3− to give a new product 1-(9-butyl-9H-carbazol-3-yl)-2-(4-(2, 2-dicyanovinyl)phenyl)ethane-1-sulfonic acid. The probe exhibits positive solvatofluorochromism with solid state red fluorescence. The restriction of intermolecular rotation of p-styryl conjugated malononitrile unit enhances the typical solid state fluorescence properties. The probe (CM and its corresponding aldehyde CA) also demonstrates a strong solvent dependence yielding blue to green to pink and even red fluorescence in commonly used organic solvents like n-hexane, toluene, diethyl ether (DEE), THF, DCM, Dioxane, CH3CN and MeOH. The chemodosimetric approach of HSO3− selectively takes place at the olefinic carbon exhibiting a prominent chromogenic as well as ratiometric fluorescence change with a 147 nm blue-shift in the fluorescence spectrum. CM can detect HSO3− as low as 1.21 × 10−8 M. Moreover, the CM can be successfully applied to detect intrinsically generated intracellular HSO3− in human peripheral blood mononuclear cells (PBMCs). CM has shown sharp intensities (2628 ± 511.8) when the cells are HSO3− untreated. At green channel (at 486 nm) almost negligible fluorescence intensities are found (423 ± 127.5) for HSO3− untreated samples. However, the green fluorescence (2863 ± 427.5) increases significantly (p < 0.05), and simultaneously the red fluorescence gets significantly (p < 0.05) diminished (515 ± 113.2) after addition of HSO3−. The CM has been effectively utilized for evaluating the bisulfite ions in food samples as well. The concentrations of HSO3− in diluted sugar samples have been determined with the recovery of 97.6–9.12%

No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR

Timing of high-count rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count-rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (~2.5 msec), and varies by a few percent event-to-event. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be modeled easily with the standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cross power density spectrum to obtain a good proxy of the white noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal to noise relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339-4, Cyg X-1 and GRS 1915+105.Comment: 13 pages, 8 figures, submitted to Ap

A hydrothermally stable Ytterbium metal-organic framework as a bifunctional solid-acid catalyst for glucose conversion

Yb6(BDC)7(OH)4(H2O)4 contains both bridging hydroxyls and metal-coordinated waters, possessing Brønsted and Lewis acid sites. The material crystallises from water at 200C. Using the solid as a heterogenous catalyst, glucose is converted into 5-hydroxymethylfurfural, via fructose, with a total selectivity of ~70 % after 24 hours at 140 C in water alone: the material is recyclable with no loss of crystallinity

Applying Recent Argumentation Methods to Some Ancient Examples of Plausible Reasoning

Plausible (eikotic) reasoning known from ancient Greek (late Academic) skeptical philosophy is shown to be a clear notion that can be analyzed by argu- mentation methods, and that is important for argumentation studies. It is shown how there is a continuous thread running from the Sophists to the skeptical philosopher Carneades, through remarks of Locke and Bentham on the subject, to recent research in artificial intelligence. Eleven characteristics of plausible reasoning are specified by analyzing key examples of it recognized as important in ancient Greek skeptical philosophy using an artificial intelligence model called the Carneades Argumentation System (CAS). By applying CAS to ancient examples it is shown how plausible reasoning is especially useful for gaining a better understanding of evidential reasoning in law, and argued that it can also be applied to everyday argumentation. Our analysis of the snake and rope example of Carneades is also used to point out some ways CAS needs to be extended if it is to more fully model the views of this ancient philosopher on argumentation

Nonredox CO2 fixation in solvent-free conditions using a Lewis acid metal–organic framework constructed from a sustainably sourced ligand

CO2 epoxidation to cyclic carbonates under mild, solvent-free conditions is a promising pathway toward sustainable CO2 utilization. Metal–organic frameworks (MOFs) explored for such applications so far are commonly composed of nonrenewable ligands such as benzene dicarboxylate (BDC) or synthetically complex linkers and therefore are not suitable for commercial utilization. Here, we report new yttrium 2,5-furandicarboxylate (FDC)-based MOFs: “UOW-1” and “UOW-2” synthesized via solvothermal assembly, with the former having a unique structural topology. The FDC linker can be derived from biomass and is a green and sustainable alternative to conventionally used BDC ligands, which are sourced exclusively from fossil fuels. UOW-1, owing to unique coordination unsaturation and a high density of Lewis active sites, promotes a high catalytic activity (∼100% conversion; ∼99% selectivity), a high turnover frequency (70 h–1), and favorable first-order kinetics for CO2 epoxidation reactions using an epichlorohydrin model substrate under solvent-free conditions within 6 h and a minimal cocatalyst amount. A systematic catalytic study was carried out by broadening the epoxide substrate scope to determine the influence of electronic and steric factors on CO2 epoxidation. Accordingly, higher conversion efficiencies were observed for substrates with high electrophilicity on the carbon center and minimal steric bulk. The work presents the first demonstration of sustainable FDC-based MOFs used for efficient CO2 utilization

Interspecies differences in metabolism of arsenic by cultured primary hepatocytes

Biomethylation is the major pathway for the metabolism of inorganic arsenic (iAs) in many mammalian species, including the human. However, significant interspecies differences have been reported in the rate of in vivo metabolism of iAs and in yields of iAs metabolites found in urine. Liver is considered the primary site for the methylation of iAs and arsenic (+3 oxidation state) methyltransferase (As3mt) is the key enzyme in this pathway. Thus, the As3mt-catalyzed methylation of iAs in the liver determines in part the rate and the pattern of iAs metabolism in various species. We examined kinetics and concentration-response patterns for iAs methylation by cultured primary hepatocytes derived from human, rat, mice, dog, rabbit, and rhesus monkey. Hepatocytes were exposed to [73As]arsenite (iAsIII; 0.3, 0.9, 3.0, 9.0 or 30 nmol As/mg protein) for 24 hours and radiolabeled metabolites were analyzed in cells and culture media. Hepatocytes from all six species methylated iAsIII to methylarsenic (MAs) and dimethylarsenic (DMAs). Notably, dog, rat and monkey hepatocytes were considerably more efficient methylators of iAsIII than mouse, rabbit or human hepatocytes. The low efficiency of mouse, rabbit and human hepatocytes to methylate iAsIII was associated with inhibition of DMAs production by moderate concentrations of iAsIII and with retention of iAs and MAs in cells. No significant correlations were found between the rate of iAs methylation and the thioredoxin reductase activity or glutathione concentration, two factors that modulate the activity of recombinant As3mt. No associations between the rates of iAs methylation and As3mt protein structures were found for the six species examined. Immunoblot analyses indicate that the superior arsenic methylation capacities of dog, rat and monkey hepatocytes examined in this study may be associated with a higher As3mt expression. However, factors other than As3mt expression may also contribute to the interspecies differences in the hepatocyte capacity to methylate iAs

A natural history study of the prognostic role of coronary arteriography

Coronary cinearteriograms, clinical records, and left ventriculograms of 304 patients studied for evaluation of chest pain were reviewed. Clinical and follow-up data on survival of the normal subjects and the nonoperative group with abnormal arteriograms are presented.Ninety-two per cent of patients with typical angina pectoris had serious coronary occlusive disease. Ninety-eight per cent of patients with relatively normal coronary arteriograms survived for one to 60 or more months (mean follow-up period 24 months).There was a high mortality rate when the left main coronary artery was involved (47 per cent) and when the left coronary anterior descending branch was seriously occluded (28 per cent when arteriographic scores were high and 14 per cent when total scores were low) and a low mortality rate (0 to 7 per cent) when the LAD was normal. Mean follow-up interval in these groups was 19 months.The mortality rate was nearly three times greater when patients had QRS changes on ECG of prior myocardial infarction and six times greater when left ventricular contraction was significantly impaired.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22297/1/0000740.pd

Optimised synthesis and further structural diversity of ytterbium benzene-1,4-dicarboxylate MOFs

The optimisation of the crystallisation of the hydrothermally-stable metal–organic framework Yb6-MOF (Yb6(BDC)7(OH)4(H2O)4) to provide a reproducible one-step synthesis is achieved by use of the sodium salt of benzene-1,4-dicarboxylate (Na2BDC) as ligand precursor and control of pH with aqueous NaOH at 190 °C over 3 days. Phase purity is confirmed using powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). During exploration of synthesis conditions from the same set of chemical reagents, three further ytterbium benzene-1,4-dicarboxylates have been isolated and structurally characterised using single-crystal X-ray diffraction, with phase purity assessed by PXRD and TGA. UOW-3 (Yb2(H2O)6(BDC)3) crystallises by lowering pH, and has a relatively dense three-dimensionally connected structure with no Yb–O–Yb linkages but dimers of Yb bridged by BDC linkers lying in the ab plane with a pseudo, pillared-layered structure, where BDC connects along c. UOW-4 (Yb4(BDC)6(H2O)6) forms under the same chemical conditions but upon lowering the temperature to 100 °C, and this material again contains no Yb–O–Yb linkages, but chains of BDC-bridged Yb centres cross-linked to give a dense three-dimensional structure. Upon increasing pH of the synthesis mixture, the material UOW-5 forms, Yb5O(OH)8(BDC)2(HBDC), consisting of dense inorganic layers of ytterbium oxyhydroxide, cross linked by BDC and HBDC pillars. The formulation is supported by infrared spectroscopy, which provides evidence for the HBDC monoanion, and also the presence of a short O–O distance indicative of hydrogen bonding between a carboxylate OH and an oxide anion of the inorganic layer. UOW-3 and UOW-4 both convert to Yb6-MOF upon heating in water above their synthesis temperature, whereas UOW-5 is hydrothermally stable at 240 °C. The structures of the new materials are discussed in terms of ligand binding modes, and connectivity of metal centres, with comparison to other reported Yb-BDC phases in order to relate structural chemistry to their synthesis conditions and the hydrothermal stability of the materials

Systematic modification of UiO‐66 metal‐organic frameworks for glucose conversion into 5‐hydroxymethyl furfural in water

Metal organic framework UiO‐66 is studied as an adaptable heterogeneous catalyst for glucose conversion. UiO‐66 was modified by; i) partial linker substitution, ii) particle size modulation and iii) linker defects. We studied the effect of crystallinity and functional groups on the glucose conversion and product yields. The main products are: i) fructose from the isomerisation of glucose, ii) mannose from the epimerisation of glucose and iii) 5‐hydroxymethyl furfural from the dehydration of fructose. We found that defective and nano crystalline UiO‐66 catalyst performs best for isomerisation. When 50 % of the linkers of UiO‐66 are replaced by a sulfonate‐containing linker, the catalyst shows higher isomerisation activity than other UiO‐66 catalysts. Naphthalene‐dicarboxylate linkers were introduced to induce hydrophobicity and this catalyst further increased isomerisation activity showing 31 % fructose selectivity. Finally, the promising catalysts were tested in a flow reactor and a bifunctional mixed linker catalyst possessing both hydrophobic and acidic functional groups is shown to be stable in a time‐on‐stream study