7,543 research outputs found

    Lt. Governor Polito Breaks Ground on $2.5 Million Downtown Revitalization Project in Leominster

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    MassWorks award supports downtown infrastructure improvements, development effort

    Assessing muscle strength for the purpose of classification in paralympic athletics: a review and recommendations

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    Objectives: Classification in Paralympic Sport aims to minimize the impact of 10 eligible types of impairment on the outcome of competition. Methods for assessing the extent to which a given body structure or function has been impaired are required, but are challenging because it is not possible to directly measure an absence or loss. Rather, impairment must be inferred by measurement of extant body structures or functions

    Photooxidation of Platinum(II) Diimine Dithiolates

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    The violet color of Pt(bpy)(bdt) (bpy = 2,2‘-bipyridine; bdt = 1,2-benzenedithiolate) is due to a Pt/S → diimine charge-transfer transition; the emission originates from the corresponding triplet state (τ = 460 ns). Photochemical oxidation of Pt(bpy)(bdt) occurs in the presence of oxygen in N,N-dimethylformamide, acetonitrile, or dimethyl sulfoxide solution; the reaction has been investigated by ^1H NMR and UV−visible absorption spectroscopy. Singlet oxygen produced by energy transfer from the excited complex is implicated as the active oxygen species, in sequential formation of sulfinate, Pt(bpy)(bdtO_2), and disulfinate, Pt(bpy)(bdtO_4), products. Both products have been characterized by X-ray crystallography. The rate of photooxygenation is strongly dependent on water concentration, and transient absorption spectra are consistent with the formation of at least one intermediate. As a whole, our data suggest that the photooxidation chemistry of platinum(II) diimine dithiolates is similar to that of organic sulfides

    Patterns of cognitive dysfunction in progressive MS

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    Background: Progressive MS is associated with a high frequency of cognitive impairment. However, it is not clear to what extent this reflects global dysfunction, or independent deficits in specific functions

    A revision of the structure of (bipyridyl-N,N')-dicyanoplatinum(II)

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    In a previous X-ray crystallographic study of crystals of Pt(bpy)(CN)_2 (bpy = 2,2'-bipyridine) the planar molecules were reported to be exactly eclipsed, stacked directly on top of one another with a spacing of 3.33 Å so as to form a linear Pt· · ·Pt· · ·Pt chain. A reinvestigation shows this structure to be incorrect. The presence of weak intermediate layer lines indicates that the repeat distance along the stacking direction is 6.66 Å rather than 3.33 Å. Successive molecules within the stack are rotated by 180° and the resulting Pt-atom chain is slightly zigzag with a Pt· · ·Pt· · ·Pt angle of 168.6 (1)°. The implications are discussed of the determination and refinement of an apparently satisfactory, although grossly wrong, structure that was based on an incorrect unit cell and an incorrect space group

    Relative age affects marathon performance in male and female athletes

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    Marathon runners are ranked in 5-year age groups. However the extent to which 5-year groupings facilitates equitable competition has not been evaluated. The aim of this study was to evaluate the effect of relative age in male and female marathon running. Marathon finishing times for the top ten male (aged 20-69 years) and female athletes (aged 20-64 years) were obtained from the 2013 New York and Chicago marathons. Intra-class and inter-class validity were evaluated by comparing performances within (intra-class) and between (inter-class) the 5-year age groups. Results showed intra-class effects in all male age groups over 50 years, in all female age groups over 40 years, and in male and female 20-24 age groups (p < 0.05). Inter-class differences existed between the 20-24 and 25-29 age groups in both males and females, between all male age groups over 50 years, and between all female age groups over 40 years (p < 0.05). This study provided the first evaluation of the effects of relative age in male and female marathon running. The results provide preliminary but compelling evidence that the relatively older male athletes in age groups over 50 years and the relatively older females in age groups over 40 years are competitively disadvantaged compared to the younger athletes in these age groups

    Emission Spectroscopic Properties of the Red Form of Dichloro(2,2‘-bipyridine)platinum(II). Role of Intermolecular Stacking Interactions

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    The structure of the red form of Pt(bpy)Cl_2 (bpy = 2,2‘-bipyridine) has been studied by variable-temperature X-ray crystallography. The stack of square-planar Pt(bpy)Cl_2 units in the linear-chain material contracts with decreasing temperature; in the interval between 294 and 20 K, the platinum−platinum distance shortens from 3.449(1) to 3.370(2) Å. Both absorption and emission spectra of the red compound depend strikingly on temperature; as previously found for tetracyanoplatinate salts, the emission maximum red-shifts as the temperature drops (613 nm at 300 K; 651 nm at 10 K), with the peak energy decreasing linearly with the inverse cube of the metal−metal separation

    Electronic Structures of Nitridomanganese(V) Complexes

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    The single-crystal polarized absorption and circular dichroism spectra of the nitridomanganese(V) complexes (salen)Mn⋮N (1), (1S,2S-(−)-saldpen)Mn⋮N (2), and (1R,2R-(+)-saldpen)Mn⋮N (3) have been measured [salen = N,N‘-ethylenebis(salicylideneaminato) dianion, 1S,2S-(−)-saldpen = N,N‘-(1S,2S-(−)-diphenyl)ethylenebis(salicylideneaminato) dianion, and 1R,2R-(+)-saldpen = N,N‘-(1R,2R-(+)-diphenyl)ethylenebis(salicylideneaminato) dianion]. As revealed by X-ray crystal structure analyses, these molecules have a distorted square-pyramidal geometry with a short Mn⋮N bond distance (1.52(3) Å for 2). The Cs compounds have a low-spin^ 1A‘[a‘(x^2 − y^2)]^2 ground state. The lowest absorption system (∼600 nm) consists of two components that are separated by approximately 4000 cm^(-1); these are assigned to ^1A‘ → ^1A‘[a‘(x^2 − y^2)a‘(yz)] (14 900 cm^(-1)) and ^1A‘ → ^1A‘‘[a‘(x^2 − y^2)a‘‘(xz)] (18 900 cm^(-1)) transitions
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