Reversible Growth of Gold Nanoparticles in the Low-Temperature Water-Gas Shift Reaction.

Supported gold nanoparticles are widely studied catalysts and are among the most active known for the low-temperature water-gas shift reaction, which is essential in fuel and energy applications, but their practical application has been limited by their poor thermal stability. The catalysts deactivate on-stream via the growth of small Au nanoparticles. Using operando X-ray absorption and in situ scanning transmission electron microscopy, we report direct evidence that this process can be reversed by carrying out a facile oxidative treatment, which redisperses the gold nanoparticles and restores catalytic activity.

N-Heterocyclic Carbene Modified Palladium Catalysts for the Direct Synthesis of Hydrogen Peroxide.

Heterogeneous palladium catalysts modified by N-heterocyclic carbenes (NHCs) are shown to be highly effective toward the direct synthesis of hydrogen peroxide (HO), in the absence of the promoters which are typically required to enhance both activity and selectivity. Catalytic evaluation in a batch regime demonstrated that through careful selection of the N-substituent of the NHC it is possible to greatly enhance catalytic performance when compared to the unmodified analogue and reach concentrations of HO rivaling that obtained by state-of-the-art catalysts. The enhanced performance of the modified catalyst, which is retained upon reuse, is attributed to the ability of the NHC to electronically modify Pd speciation.

Researcher degrees of freedom in statistical software contribute to unreliable results: A comparison of nonparametric analyses conducted in SPSS, SAS, Stata, and R.

Researcher degrees of freedom can affect the results of hypothesis tests and consequently, the conclusions drawn from the data. Previous research has documented variability in accuracy, speed, and documentation of output across various statistical software packages. In the current investigation, we conducted Pearson's chi-square test of independence, Spearman's rank-ordered correlation, Kruskal-Wallis one-way analysis of variance, Wilcoxon Mann-Whitney U rank-sum tests, and Wilcoxon signed-rank tests, along with estimates of skewness and kurtosis, on large, medium, and small samples of real and simulated data in SPSS, SAS, Stata, and R and compared the results with those obtained through hand calculation using the raw computational formulas.

Retrolabyrinthine transsigmoid approach to complex parabrainstem tumors in the posterior fossa.

Objective: The surgical management of large and complex tumors of the posterior fossa poses a formidable challenge in neurosurgery. The standard retrosigmoid craniotomy approach has been performed at most neurosurgical centers; however, the retrosigmoid approach may not provide enough working space without significant retraction of the cerebellum. The transsigmoid approach provides wider and shallower surgical fields; however, there have been few clinical and no cadaveric studies on its usefulness.

Enhancing the understanding of the glycerol to lactic acid reaction mechanism over AuPt/TiO under alkaline conditions.

The oxidation of glycerol under alkaline conditions in the presence of a heterogeneous catalyst can be tailored to the formation of lactic acid, an important commodity chemical. Despite recent advances in this area, the mechanism for its formation is still a subject of contention. In this study, we use a model 1 wt.

Rationalization of the X-ray photoelectron spectroscopy of aluminium phosphates synthesized from different precursors.

The aim of this paper is to clarify the assignments of X-ray photoelectron spectra of aluminium phosphate materials prepared from the reaction of phosphoric acid with three different aluminium precursors [Al(OH), Al(NO) and AlCl] at different annealing temperatures. The materials prepared have been studied by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), infrared spectroscopy and high-resolution solid-state P NMR spectroscopy. A progressive polymerization from orthophosphate to metaphosphates is observed by XRD, ATR-FTIR and solid state P NMR, and on this basis the oxygen states observed in the XP spectra at 532.

Efficient Elimination of Chlorinated Organics on a Phosphoric Acid Modified CeO Catalyst: A Hydrolytic Destruction Route.

The development of efficient technologies to prevent the emission of hazardous chlorinated organics from industrial sources without forming harmful byproducts, such as dioxins, is a major challenge in environmental chemistry. Herein, we report a new hydrolytic destruction route for efficient chlorinated organics elimination and demonstrate that phosphoric acid-modified CeO (HP-CeO) can decompose chlorobenzene (CB) without forming polychlorinated congeners under the industry-relevant reaction conditions. The active site and reaction pathway were investigated, and it was found that surface phosphate groups initially react with CB and water to form phenol and HCl, followed by deep oxidation.

Enhanced Activity and Stability of Gold/Ceria-Titania for the Low-Temperature Water-Gas Shift Reaction.

Gold supported on ceria-zirconia is one of the most active low temperature water-gas shift catalysts reported to date but rapid deactivation occurs under reaction conditions. In this study, ceria-titania was evaluated as an alternative catalyst support. Materials of different Ce:Ti compositions were synthesized using a sol-gel methodology and gold was supported onto these using a deposition-precipitation method.

Investigating the Influence of Fe Speciation on NO Decomposition Over Fe-ZSM-5 Catalysts.

The influence of Fe speciation on the decomposition rates of NO over Fe-ZSM-5 catalysts prepared by Chemical Vapour Impregnation were investigated. Various weight loadings of Fe-ZSM-5 catalysts were prepared from the parent zeolite H-ZSM-5 with a Si:Al ratio of 23 or 30. The effect of Si:Al ratio and Fe weight loading was initially investigated before focussing on a single weight loading and the effects of acid washing on catalyst activity and iron speciation.

A Kinetic Study of Methane Partial Oxidation over Fe-ZSM-5 Using N O as an Oxidant.

Catalytic methane oxidation using N O was investigated at 300 °C over Fe-ZSM-5. This reaction rapidly produces coke (retained organic species), and causes catalyst fouling. The introduction of water into the feed-stream resulted in a significant decrease in the coke selectivity and an increase in the selectivity to the desired product, methanol, from ca.

Activation and Deactivation of Gold/Ceria-Zirconia in the Low-Temperature Water-Gas Shift Reaction.

Gold (Au) on ceria-zirconia is one of the most active catalysts for the low-temperature water-gas shift reaction (LTS), a key stage of upgrading H reformate streams for fuel cells. However, this catalyst rapidly deactivates on-stream and the deactivation mechanism remains unclear. Using stop-start scanning transmission electron microscopy to follow the exact same area of the sample at different stages of the LTS reaction, as well as complementary X-ray photoelectron spectroscopy, we observed the activation and deactivation of the catalyst at various stages.

Supercritical Antisolvent Precipitation of Amorphous Copper-Zinc Georgeite and Acetate Precursors for the Preparation of Ambient-Pressure Water-Gas-Shift Copper/Zinc Oxide Catalysts.

A series of copper-zinc acetate and zincian georgeite precursors have been produced by supercritical CO antisolvent (SAS) precipitation as precursors to Cu/ZnO catalysts for the water gas shift (WGS) reaction. The amorphous materials were prepared by varying the water/ethanol volumetric ratio in the initial metal acetate solutions. Water addition promoted georgeite formation at the expense of mixed metal acetates, which are formed in the absence of the water co-solvent.

The effect of sodium species on methanol synthesis and water-gas shift Cu/ZnO catalysts: utilising high purity zincian georgeite.

The effect of sodium species on the physical and catalytic properties of Cu/ZnO catalysts derived from zincian georgeite has been investigated. Catalysts prepared with <100 ppm to 2.1 wt% Na, using a supercritical CO antisolvent technique, were characterised and tested for the low temperature water-gas shift reaction and also CO hydrogenation to methanol.

Synergy and Anti-Synergy between Palladium and Gold in Nanoparticles Dispersed on a Reducible Support.

Highly active and stable bimetallic Au-Pd catalysts have been extensively studied for several liquid-phase oxidation reactions in recent years, but there are far fewer reports on the use of these catalysts for low-temperature gas-phase reactions. Here we initially established the presence of a synergistic effect in a range of bimetallic Au-Pd/CeZrO catalysts, by measuring their activity for selective oxidation of benzyl alcohol. The catalysts were then evaluated for low-temperature WGS, CO oxidation, and formic acid decomposition, all of which are believed to be mechanistically related.

Stable amorphous georgeite as a precursor to a high-activity catalyst.

Copper and zinc form an important group of hydroxycarbonate minerals that include zincian malachite, aurichalcite, rosasite and the exceptionally rare and unstable--and hence little known and largely ignored--georgeite. The first three of these minerals are widely used as catalyst precursors for the industrially important methanol-synthesis and low-temperature water-gas shift (LTS) reactions, with the choice of precursor phase strongly influencing the activity of the final catalyst. The preferred phase is usually zincian malachite.

Primary spinal intramedullary adrenal cortical adenoma associated with spinal dysraphism: case report.

Objective: The authors report a primary spinal intramedullary adrenal cortical adenoma in a patient with spinal dysraphism presenting with bilateral leg pain and urinary frequency.

Methods: Magnetic resonance imaging, L2 laminectomy with resection of mass, and pathological and immunohistochemical analysis of resected mass revealed the diagnosis.

Results: Microscopic and immunohistochemical findings confirmed the diagnosis as a primary intramedullary tumor of adrenal cortical origin.

Religion/spirituality in African-American culture: an essential aspect of psychiatric care.

There is an astonishing diversity of religious beliefs and practices in the history of African Americans that influences the presentation, diagnosis, and management of both physical and mental disorders. The majority of African Americans, however, are evangelical Christians with religious experiences originating in the regions of ancient Africa (Cush, Punt, and to a great extent, Egypt), as well as black adaptation of Hebraic, Jewish, Christian, and Islamic beliefs and rituals. Consequently, more than 60 of the nation's 125 medical schools offer classes in spirituality and health.