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The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H2O2 concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., •OH, HO2•/O2•-) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO2• or O2•- radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of •OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions. [ABSTRACT FROM AUTHOR]

The discovery of the genetic basis for circadian rhythms has expanded our knowledge of the temporal organization of behavior and physiology. The observations that the circadian gene network is present in most living organisms from eubacteria to humans, that most cells and tissues express autonomous clocks, and that disruption of clock genes results in metabolic dysregulation have revealed interactions between metabolism and circadian rhythms at neural, molecular, and cellular levels. A major challenge remains in understanding the interplay between brain and peripheral clocks and in determining how these interactions promote energy homeostasis across the sleep-wake cycle. In this Review, we evaluate how investigation of molecular timing may create new opportunities to understand and develop therapies for obesity and diabetes. [ABSTRACT FROM AUTHOR]

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts. [ABSTRACT FROM AUTHOR]

Speciation of arsenic has increasingly been a crucial work for research, management, assessment and treatment of arsenic in different environmental media. Simple and efficient methods are urgently needed for the speciation of the two most important arsenic species, inorganic As(V) and As(III), which are both more toxic and ubiquitous in water and soil than other forms. In this paper, we report a difference method for the speciation of inorganic As(V) and As(III) at submicrogram per liter levels in water by hydride generation-atomic fluorescence spectrometry (HG-AFS). Controlling different concentrations of HCI and NaB H4 in the reduction and hydride generation of As(V) and As(III), no additional reductant was needed. As(III) could be determined by HG-AFS with 2% HCl - 1.5% KBH4, while 8% HCl - 6.0% KBH4 was an efficient combination for detecting total As and As(V). This method was coupled to microwave-assisted extraction, using H3PO4 and L-ascorbic acid (VC) as co-extractants, for the determination of inorganic As(V)/As(III) in soils. Neither ions in the seawater matrix nor soil humics created any interference in the speciation of As(V)/As(III). Applications of this method were demonstrated in lake water, river water and soils with satisfactory results. [ABSTRACT FROM AUTHOR]

A continuing goal in catalysis is to unite the advantages of homogeneous and heterogeneous catalytic processes. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this unification can also be supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl2, and catalyse a range of π-bond activation reactions previously only catalysed through homogeneous processes. Multiple experimental methods are used to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, a size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared with larger, polymer-capped analogues. [ABSTRACT FROM AUTHOR]

Photochemical processes (PCPs), which can be regarded as a new kind of Advanced Oxidation Technology (AOT), are widely used and largely involved in many kinds of chemical reactions as well as some actual applications in practical pollutant treatments. In this mini-review, we have presented a comprehensive report of the recent progress in the study of PCP-experimental work, in the view of AOTs technical development. Dominating conditions including light sources, catalysts and reactors are summarized, and the development of related researches is characterized in the hope of giving some basis and illumination to following researchers. [ABSTRACT FROM AUTHOR]

The shape dependence of the catalytic reduction of nitric oxide by carbon monoxide on rhodium nanopolyhedra and nanocubes was studied from 230 to 270 °C. The nanocubes are found to exhibit higher turnover frequency and lower activation energy than the nanopolyhedra. These trends are compared to previous studies on Rh single crystals. [ABSTRACT FROM AUTHOR]

Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as ∼1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H 2after reduction (76 torr of H 2mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation. [ABSTRACT FROM AUTHOR]

Localized surface plasmon resonances (LSPR) in lithographically fabricated gold (Au) nanodisc pairs are investigated using microabsorption spectroscopy and electrodynamic simulations. In agreement with previous work, we find that the fractional plasmon wavelength shift for polarization along the interparticle axis decays nearly exponentially with the interparticle gap. In addition, we find that the decay length is roughly about 0.2 in units of the particle size for different nanoparticle size, shape, metal type, or medium dielectric constant. The near-exponential distance decay and the interesting “universal” scaling behavior of interparticle plasmon coupling can be qualitatively explained on the basis of a dipolar-coupling model as being due to the interplay of two factors:  the direct dependence of the single-particle polarizability on the cubic power of the particle dimension and the decay of the plasmonic near-field as the cubic power of the inverse distance. Using this universal scaling behavior, we are able to derive a “plasmon ruler equation” that estimates the interparticle separation between Au nanospheres in a biological system from the observed fractional shift of the plasmon band. We find good agreement of the interparticle separations estimated using this equation with the experimental observations of Reinhard et al. (Nano Lett.2005, 5, 2246−2252). [ABSTRACT FROM AUTHOR]

The article discusses a quiz question concerning the appropriate treatment for a 36-year-old woman who presented with symptoms including weight loss and shortness of breath, and was then diagnosed with thymic hyperplasia as a complication of Graves disease. Laboratory results including an above-normal thyroid-stimulating hormone (TSH) level are noted, and diagnostic images including a computed tomography (CT) scan of her chest are included.

Ethylene oxide (EO) is one of the most crucial materials in plastic industries. The traditional catalytic process requires high temperature and pressure to produce EO. A chlorine-assisted system has been reported to produce EO, but it required noble metal catalysts, which significantly increased the cost. In this work, a MOF-derived Co3O4/nitrogen-doped carbon composite (Co3O4/NC) prepared through a two-step calcination method exhibited remarkable chlorine evolution reaction (ClER) activity as compared with a commercial RuO2 catalyst, which can be attributed to the higher specific surface area and lower resistance of its porous structure and nitrogen-doped carbon. Furthermore, the Co3O4/NC maintained a stable potential and a high faradaic efficiency throughout the 10-hour electrolysis test. [ABSTRACT FROM AUTHOR]

Control of structure at the atomic level can precisely and effectively tune catalytic properties of materials, enabling enhancement in both activity and durability. We synthesized a highly active and durable class of electrocatalysts by exploiting the structural evolution of platinum-nickel (Pt-Ni) bimetallic nanocrystals. The starting material, crystalline PtNi3 polyhedra, transforms in solution by interior erosion into Pt3Ni nanoframes with surfaces that offer three-dimensional molecular accessibility. The edges of the Pt-rich PtNi3 polyhedra are maintained in the final Pt3Ni nanoframes. Both the interior and exterior catalytic surfaces of this open-framework structure are composed of the nanosegregated Pt-skin structure, which exhibits enhanced oxygen reduction reaction (ORR) activity. The Pt3Ni nanoframe catalysts achieved a factor of 36 enhancement in mass activity and a factor of 22 enhancement in specific activity, respectively, for this reaction (relative to state-of-the-art platinum-carbon catalysts) during prolonged exposure to reaction conditions. [ABSTRACT FROM AUTHOR]

The article focuses on the highly selective synthesis of catalytically active and monodisperse rhodium nanocubes smaller than 10 nanometer (nm) by a polycol method. According to the authors, Rh inorganic nanocrystals (NCs) are used in catalytic reactions including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. They concluded that the one-step polyol route can be readily applied to the preparation of platinum (Pt) and palladium (Pd) nanocubes.

The article discusses the role that pancreatic B (Beta) cell enhancers play in regulating the circadian rhythm of the genetic transcription that controls the secretion of insulin, including regard to the regulation of the genes CLOCK and BMAL1. The impact that the circadian clock has on maintaining the homeostasis of glucose levels in the body is discussed.