Alternatives to platinum‐based catalysts are required to sustainably produce hydrogen from water at low overpotentials. Progress has been made in utilizing tungsten carbide‐based catalysts, however, ...their performance is currently limited by the density and reactivity of active sites, and insufficient stability in acidic electrolytes. We report highly active graphene nanoplatelet‐supported tungsten carbide–nitride nanocomposites prepared via an in situ solid‐state approach. This nanocomposite catalyzes the hydrogen evolution reaction with very low overpotential and is stable operating for at least 300 h in harsh acidic conditions. The synthetic approach offers a great advantage in terms of structural control and kinetics improvement.
Win–WN situation: A graphene nanoplatelet‐supported electrocatalyst comprised of nanostructured tungsten carbide (W2C) and tungsten nitride (WN) generates hydrogen efficiently in acidic water. Anchoring the W2C–WN onto graphene nanoplatelets greatly reduces the charge transfer resistance and accelerates the proton discharge kinetics. The overpotential (η10) is 120 mV, which is among the best of non‐noble metal catalysts reported to date.
Platinum(II) bi- and terpyridyl chloro complexes, Pt(dcbpy)Cl2 and Pt(ttpy)Cl+, where dcbpy = 4,4′-dicarboxyl-2,2′-bipyridine and ttpy = 4-tolyl-2,2′:6′,2″-terpyridine, are used to investigate the ...nature of the active catalyst for the photocatalytic production of hydrogen from water. In a Pt(II) chloro system that contains a sacrificial electron donor, either MeOH or triethanolamine (TEOA), and titanium dioxide (TiO2) as an electron relay, sizable amounts of H2 can be observed upon UV bandgap irradiation. The quantity of H2 can be significantly reduced in the presence of mercury under the same conditions. Using a known sensitizer, Pt(ttpy)(phenylacetylide)+ (1), combined with a Pt(II) chloro complex in a similar system, there is a substantial induction period until the evolution of H2, under visible light (λ > 410 nm) irradiation. It is suggested that the Pt(II) chloro complexes are simply acting as precursors to Pt colloids that function as the H2 generating catalyst
This book is an English translation of the Draft Chinese Civil Code prepared by the Legislative Group of the Chinese Academy of Social Sciences headed by Prof. Liang Huixing, which is officially ...mandated by the Legislative Committee of the National People's Congress of the People's Republic of China.
New platinum(II) terpyridyl acetylide complexes having the ability to bind to TiO2 have been synthesized and assayed in their ability to sensitize platinized titanium dioxide for the photogeneration ...of H2 using visible light (λ > 410 nm). Specifically, the complexes Pt(tpy-phen-COOH)(CC−C6H5)Cl (1), where tpy-phen-COOH = 4′-(4-carboxyphenyl)-2,2′;6′,2′′terpyridine and CC−C6H5 = phenylacetylide, and Pt(tpy-COOH)(CC−C6H5)Cl (2), where tpy-COOH = 4′-carboxy-2,2′;6′,2′′-terpyridine, were prepared to investigate the effectiveness of attachment and proximity to the TiO2 surface on hydrogen yield. Both complexes 1 and 2 sensitize the photogeneration of hydrogen, but produce fewer turnovers than the unbound chromophore, Pt(ttpy)(CC−C6H5)PF6 (5). On the basis of these observations and electrochemical data, a major limitation to the effectiveness of these chromophores is their instability upon oxidation. To attempt to remedy this problem, two donor-chromophore (D-C) dyads, Pt(tpy-phen-COOH)(CC−C6H4CH2−PTZ)PF6 (3), where CC−C6H4CH2−PTZ = N-(4-ethynylbenzyl)-phenothiazine and Pt(tpy-COOH)(CC−C6H4CH2−PTZ)Cl (4) were prepared to function as TiO2-attached sensitizers. Transient absorption measurements have shown that the PTZ moiety reductively quenches the Pt center in several picoseconds. While the resultant PTZ+ radical cation is capable of oxidizing rapidly the triethanolamine sacrificial electron donor, dyads 3 and 4 attached to platinized TiO2 do not function to generate hydrogen upon irradiation, in contrast with results seen for 1 and 2.
Photocatalytic CO(2) reduction has been studied for two dyads with porphyrin covalently attached to rhenium tricarbonyl bipyridine moieties, and on separate components consisting of ...Re(CO)(3)(Picoline)Bpy(+) and either zinc porphyrin or zinc chlorin. TONs decrease in the order: zinc porphyrin + Re > long spacer dyad > zinc chlorin + Re > short spacer dyad.
Four new Pt(II) terpyridyl acetylide complexes which possess a covalently linked nitrophenyl moiety were prepared and studied. Specifically, the chromophore−acceptor (C−A) dyads reported here include ...Pt(ptpy-ph-p-NO2)(CC−C6H5)(PF6)3 (1), where ptpy-ph-p-NO2 = 4′-{4-(4-nitrophenyl)-phenyl}-2,2′;6′,2′′terpyridine, and CC−C6H5 = phenylacetylide and Pt(ptpy-ph-m-NO2)(CC−C6H5)(PF6)2 (2), where ptpy-ph-m-NO2 = 4′-(4-m-nitrophenyl-phenyl)-2,2′;6′,2′′-terpyridine, as well as the related donor−chromophore−acceptor (D−C−A) triads Pt(ptpy-ph-p-NO2)(CC−C6H4CH2−PTZ)PF6 (3), where CC−C6H4CH2−PTZ = 4-ethynylbenzyl-N-phenothiazine, and Pt(ptpy-ph-m-NO2)(CC−C6H4CH2−PTZ)PF6 (4). Transient absorption spectroscopy and electrochemical analyses were used to characterize these compounds. In contrast to previous observations for closely related multicomponent systems, it appears that, in the current systems, the nitrophenyl group is not an effective quencher of the excited state. The luminescence and transient absorption properties of the C−A dyads are virtually identical to those of the parent chromophore, Pt(ttpy)(CC−C6H5)PF6 (5), where ttpy = 4′-p-tolyl-2,2′;6′,2′′terpyridine.
Introduction/background: Osteoporosis is a common disorder and is associated with an increased risk of bone fracture. Falls are a proximate cause of a high proportion of medical costs and mortality. ...Improving balance can reduce the risk of falls and improve health outcomes, especially for the at-risk population of people with osteoporosis and osteopenia. The FrameWorksTM exercise program is a formal, standardized, informational and interventional 10-month exercise program. The purpose of this study was to quantitatively assess the improvement in standing balance, functional reach, and overall confidence in balance after participating in the 10-month program. Methodology: This study is a prospectively designed study with a pre and post study measurement of balance metrics. Sixty-two female participants, 45 years of age or older and at increased risk for fragility fractures, completed the 10-month program as well the pre and post program testing. Confidence was measured with the Activities-specific Balance Confidence Scale, a self-reported survey. Balance was measured digitally by means of testing with a NeuroCom® Basic Balance Master® system. Measurements were made of the Limits of Stability (LOS) Test and Modified Clinical Test of Sensory Interaction on Balance (mCTSIB). Balance was clinically assessed with the Functional Reach Test (FRT). Results: Participation in the 10 months FrameWorksTM program resulted in improvement in quantitative measures of balance (Composite Sway Velocity, −12%, p < 0.001; End point excursion, 17.1%, p < 0.000001). A clinical measure of balance, the Functional Reach Test, improved, (2.9 cm, p < 0.0001). Participation also resulted in improvement in balance confidence (9.4 %, p < 0.00001). A height increase was observed (0.6 cm, p < 0.000001). Conclusions: The 10-month FrameWorksTM program improves balance and confidence in women at risk for fragility fractures. By improving balance and confidence, people are less likely to fall and therefore sustain fewer fractures and associated injuries.
Three new cyclometalated 6-phenyl-4-(p-R-phenyl)-2,2′-bipyridyl (C∧N∧N) Pt(II) thiophenolate complexes (R = Me (2a), COOMe (2b), and P(O)(OEt)2 (2c)) have been synthesized and studied. The new C∧N∧N ...ligands L2 (R = COOMe) and L3 (R = P(O)(OEt)2) undergo cyclometalation with a Pt(II) source to give the Pt(II) chloro complexes 1b and 1c, respectively, which are luminescent in fluid solution with λmax ∼ 575 nm, assigned to a metal-to-ligand charge-transfer (3MLCT) emissive state. Reaction of the chloro complexes 1a (R = Me), 1b, and 1c with sodium thiophenolate gives 2a−2c, respectively, in good yields. The novel thiophenolate complexes have two interesting absorption bands in their electronic spectra tentatively assigned to a charge-transfer to C∧N∧N (1CT) (λabs ∼415 nm) transition and a mixed metal/ligand-to-ligand′ charge-transfer (MMLL′CT, λabs ∼ 555 nm) transition, respectively. The MMLL′CT band is solvatochromic with absorption maxima in the range of 496 nm in MeOH to 590 nm in toluene (ε ∼ 4000 dm3 mol−1 cm−1), which correlate well with an empirical charge-transfer-based solvent scale. Excitation of 2a−2c into the MMLL′CT band gives emission maxima around 680 nm in frozen CH2Cl2 solution, and no emission in fluid solution. Ligand L2 and complexes 1a·MeCN, 1b, and 2b·CH2Cl2 have been characterized by single crystal X-ray crystallography. The electrochemical properties of ligands L1 (R = Me) and L2 and complexes 1a−1c and 2a−2c have been examined by cyclic voltammetry and are shown to exhibit reversible and quasi-reversible reductions and irreversible oxidations.
The Indian River Lagoon (IRL) is an Estuary of National Significance with numerous documented harmful algal blooms (HABs). Light microscopy is routinely used to identify IRL HABs, including ...Pseudo-nitzschia spp. and Pyrodimiim bahamense. Smaller-sized nanoplankton, such as the brown tide alga, Aiireoumbra lagunensis, can be difficult to definitively identity, but a network for enhanced monitoring was initiated in the IRL after large nanoplankton blooms in 2011, 2012, and 2013. We present monitoring results from samples collected between 2015-2020 and examined for HAB abundance using microscopy. We also used immunofluorescence flow cytometry and a newly developed qPCR approach to confirm the presence of A. lagunensis during bloom and non-bloom periods. Blooms of A. lagunensis (>200 million cells/L) were observed in all years and across seasons. In contrast, P. bahamense displayed a strong seasonal pattern with blooms (>100,000 cells/L) generally developing in early summer and subsiding in autumn. Pseudo-nitzschia spp. were broadly distributed and blooms (>100,000 cells/L) were more sporadic. In summer 2020, a bloom of a nano-sized cyanobacterium was first detected in the northern IRL, expanded to other subbasins, and persisted into December. It is not yet clear if this alga occurred in the IRL prior to this event, but genetic and microscopic analyses suggest it represents a novel taxon. While high biomass blooms of nano-sized algae have been prevalent over the last decade, statistical analyses suggest that environmental conditions preceding or coinciding with these large-scale blooms have varied and may be event-driven. These blooms, however, may act as overriding controls that influence seasonal occurrences of other phytoplankton taxa. Sustained and enhanced monitoring coupled with physiology/life cycle studies for IRL HABs will help provide further insight into mechanisms underlying likely patterns of species succession over seasonal to interannual timescales.
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