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High intracranial pressure (ICP) can impede cerebral blood flow resulting in secondary injury or death following severe stroke. Compensatory mechanisms include reduced cerebral blood and cerebrospinal fluid volumes, but these often fail to prevent raised ICP. Serendipitous observations in intracerebral hemorrhage (ICH) suggest that neurons far removed from a hematoma may shrink as an ICP compliance mechanism. Here, we sought to critically test this observation. We tracked the timing of distal tissue shrinkage (e.g. CA1) after collagenase-induced striatal ICH in rat; cell volume and density alterations (42% volume reduction, 34% density increase; p p ≤ 0.007), but not with the Vannucci-Rice model of hypoxic-ischemic encephalopathy (2.5% volume increase, 14% density increase; p ≥ 0.05). Concerningly, this ‘tissue compliance’ appears to cause sub-lethal damage, as revealed by electron microscopy after ICH. Our data challenge the long-held assumption that ‘healthy’ brain tissue outside the injured area maintains its volume. Given the magnitude of these effects, we posit that ‘tissue compliance’ is an important mechanism invoked after severe strokes.

Various forms of cobalt catalysts have been studied extensively for selective aerobic oxidation of hydrocarbons. However, it remains unclear whether cobalt can directly activate molecular oxygen under mild reaction conditions. Here we investigated the catalytic roles of cobalt in ethylbenzene oxidation with and without a hydroperoxide initiator. The contribution of different cobalt species was studied by varying the metal loading on Co-impregnated ZSM-5 samples. Quantitative EPR was used to determine the impact of cobalt catalysts on the free radical concentrations. This work provided strong evidence that cobalt, in several different forms, catalyzes hydrocarbon oxidation by facilitating peroxy bond cleavage, instead of direct oxygen activation.

Catalytic oxidation of organic pollutants is an attractive and sustainable method of water purification. This paper focuses on discussion of catalytic activity, selectivity, and stability in cataly...

Aerobic oxidation of α-C H bond of organic compounds to valuable chemicals is widely investigated in both fundamental research and industry. Due to the good stability of molecular oxygen, severe reaction conditions are generally required. Herein, by in situ synthesis we used molecular oxygen to induce cobalt nanoclusters with the sensitive catalysis in mild selective oxidation. The cobalt containing clusters with an average diameter around 0.9 nm are in situ prepared in the presence of cis-cyclooctene epoxidation and cyclooctene dimer oxide is formed at the interface to stabilize Co clusters with electron donation as an oil-soluble surfactant. The soluble clusters exhibit high activity in selective oxidation of α-C H bond of ethylbenzene into acetophenone and turnover number (TON) reaches about 7 × 104 during 50 h’ reaction at 373 K, which is around 960 times more active than the one using CoCl2 salt as the catalyst, resulting from efficient mass transportation, π bond interaction and oxygen gas activation. Extended work based on this understanding demonstrates that cobalt nanoclusters also effectively catalyze aerobic oxidation of cyclohexene.

BACKGROUND Eczema or Atopic Dermatitis (AD) is a common chronic relapsing skin disease associated with impaired quality of life. Regular usage of moisturizer/emollient is the mainstay of management but acceptability of emollient is often suboptimal. We investigated if emollient acceptability is influenced by various clinical factors in AD. METHODS A survey on frequency of emollient usage, brands, clinical factors including disease severity (Nottingham Eczema Severity Score, NESS), quality of life (Children Dermatology Life Quality Index, CDLQI), Transpidermal Water Loss (TEWL), and Skin Hydration (SH) was performed. Acceptability was classified as very good, good, fair or poor. RESULTS We evaluated 128 AD patients. NESS correlated with CDLQI and the treatment domain of CDLQI. Emollient usage is elementary for AD treatment. 89.1% of patients reported that doctor's recommendation was the major source of advice when choosing an emollient. Aqueous cream (AQ) and petroleum-derived products were among the commonly used emollients. More aqueous cream users reported fair/poor acceptability (p=0.017) and lower SH (p

Aim Eczema or Atopic Dermatitis (AD) is associated with itch, sleep disturbance, impaired life quality, reduced skin hydration, impaired epidermal barrier function and colonization by Staphylococcus aureus (SA). We investigated an emollient with claimed multi-actions on barrier repair, antihistaminergic and antimicrobial effects. Methods Consecutive AD patients were recruited. Swabs and cultures from eczematous areas, disease severity (SCOring Atopic Dermatitis score: SCORAD), quality-of-life (Children Dermatology Life Quality Index, CDLQI), Skin Hydration (SH), and Transepidermal Water Loss (TEWL) were obtained before and 4-week following usage of the emollient. Global or General Acceptability of Treatment (GAT) was obtained (as very good, good, fair or poor). Results 30 AD patients were recruited. 73% reported "very good" or "good", whereas 27% reported "fair" or "poor" GAT of the emollient. Following the use of the multi-action emollient, area affected, disease intensity and severity significantly improved, especially in the very good/good group (p=0.006-0.035). There was no significant improvement of itch or sleep scores, quality of life, SH, TEWL, S. aureus colonization status, or use of topical treatments. When compared with the historical data of another product, there was no statistical difference between the two creams. Conclusion The emollient is acceptable in nearly three-quarter of AD patients. Patients that accept the moisturizer have less area affected, disease intensity and severity than the non-accepting counterparts following its usage. Despite claim for multi-action, there were no appreciable quality-oflife, anti-itch, skin barrier, and anti-microbial effects.

Interfacial perimeter sites between metal and support are often important for catalysis. A mononuclear titanium siloxy complex III, Ti(acac)2[OSiC6H5N(OCH3)2]2 was synthesized to generate TiOx units of different degrees of clustering to decorate Au nanoparticles. Two different methods of preparation were examined; one was to deposit III onto Au/SiO2 and the other was to form III-covered Au nanoparticle first before deposition onto SiO2. The former method generated more highly dispersed TiOx units, while larger domains of TiO2 were formed with the latter method, as deduced by UV–vis and XAS characterization. A model was proposed to explain how TiOx dispersity could be related to the preparative procedures. These samples were further tested as catalysts in selective oxidation of propane in a stream of O2 and H2. They exhibited different product selectivities. The sample with more dispersed TiOx units were more selective for acetone formation versus propene formation. The results confirmed the important role of both the Au–TiOx interface at the perimeter and the extent of Ti isolation in the TiOx phase in the reaction.

Ternary metal fluoride Fe x Mn 1−x F 2 (x = 0.00, 0.25, 0.50, 0.75, and 1.00), which is a potential cathode material for next-generation Li-ion batteries, were synthesized via a convenient, low-temperature, bottom-up solution-phase method. The lattice dimensions deduced from X-ray diffraction suggested formation of homogeneous solid solutions. With increasing Fe content, the morphology of the solid changed from cubic particles to dendritic, with an average particle size of 20–40 nm. The results suggested that this synthetic method constitutes a translatable route to large-scale production of ternary metal fluoride nanoparticles.

Inverse gas chromatography (IGC) was employed in evaluating the catalytic surface of meso-microporous KIT-6 impregnated Ni (0.5–2.0 wt%) in methane dry reforming reaction. The free energy of adsorption did not changed significantly for the sample modified with highly dispersed Ni species (0.5 wt%). At higher Ni loadings, higher free energy of adsorption and enthalpy of adsorption of the probes were observed, together with high dispersive interaction and specific interaction of aromatics. The results indicated that during the impregnation, Ni species preferably penetrated into the microporous region to form Ni particles and became ‘unaccessible’. This feature was used to understand the dependence of activity on Ni loading for the gas phase catalytic methane reforming with carbon dioxide on Ni/KIT-6. The lower TOF at low metal loadings was attributed to Ni particles located in the micropores which result in diffusional constraint of reactants and products.

Electrically conducting, 3D elastomeric composite foams are fabricated successfully using multiple cycles of infusing polyurethane foams with graphene oxide sheets followed by reduction, to form coatings of reduced graphene oxide up to ∼1260 nm thick. The reduced graphene oxide coating increases the compression modulus of the composite and lowers the electrical resistance significantly compared with polyurethane foam, the extents of which increase with increasing coating thickness. The electrical resistance of the coated foams varies by as much as three orders of magnitude for coating thickness between ∼150 and ∼1200 nm, whereas the capacitance varies by one order of magnitude. Both the stress-strain and the resistance-strain behavior are highly repeatable with compression cycles performed up to 70% strain. Both SEM and X-ray tomography characterization show that deformation is mostly through bending of the pore walls up to about 20% strain, collapse of pore openings to about 60% strain, and densification beyond that. Micro-fractures also develop on the coating during the first few cycles of compression, but no obvious structural changes can be detected afterwards.

Grafting of pairs of functional groups onto a silica surface was demonstrated by tethering both terminals of an organochlorosilane precursor molecule, Cl2(CH3)Si(CH2)4(CO)(OSi(i-Pr)2)(CH2)2Si(CH3)Cl2, that possess a cleavable silyl ester bond, onto a silica surface. Hydrolytic cleavage of the silyl ester bond of the grafted molecule resulted in the generation of organized pairs of carboxylic acid and organosilanol groups. This organosilanol moiety was easily transformed into other functional groups through condensation reactions to form, together with the neighboring acid group, pairs such as carboxylic acid/secondary amine, carboxylic acid/pyridine, and carboxylic acid/phosphine. In the case of carboxylic acid/amine pairing, there was evidence of the formation of amide. A sample grafted with amine–carboxylic acid pairs was three times more active (per free amine) than a sample without such pairs for the nitroaldol condensation of 4-nitrobenzaldehyde and nitromethane.

There is an urgent need to provide adequate and sustainable supplies of water and food to satisfy the demand of an increasing population. Catalysis plays important roles in meeting these needs by facilitating the synthesis of hydrogen peroxide that is used in water decontamination and chemicals production, and ammonia that is used as fertilizer. However, these chemicals are currently produced with processes that are either very energy-intensive or environmentally unfriendly. This article offers the perspectives of the challenges and opportunities in the production of these chemicals, focusing on the roles of catalysis in more sustainable, alternative production methods that minimize energy consumption and environmental impact. While not intended to be a comprehensive review, the article provides a critical review of selected literature relevant to its objectives, discusses areas needed for further research, and potential new directions inspired by new developments in related fields. For each chemical, production by thermal, electro-, and photo-excited processes are discussed. Problems that are common to these approaches and their differences are identified and possible solutions suggested.

A comprehensive research project consisting of pilot-scale combustion testing and long-term laboratory corrosion study has been performed. A pilot-scale combustion facility was modified to enable burning of pulverized coals under the conditions typical for coal-fired utility boilers. Eight United States (U.S.) coals were selected for this investigation, with the test conditions for all coals set to have the same heat input to the combustor. In addition, the air/fuel ratio was controlled so that approximately 3% excess oxygen was attained in the combustion gas at the furnace outlet, a location equivalent to the furnace exit of commercial boilers. During each pilot-scale combustion test, extensive online measurements of the flue gas compositions were performed. In addition, deposit samples were collected at the same location for chemical analyses. This information characterized well the combustion environments adjacent to the superheaters and reheaters of utility boilers burning different U.S. coals. The ga...

Amine-functionalized siloxane oligomers were synthesized and used successfully to prepare colloidal Au particles smaller than 1 nm. Using NMR to follow the interaction of Au(THT)Cl with the functionalized siloxane, it was determined that the amine ligands displaced the THT ligand effectively. By comparison with other functionalized siloxane oligomers/compound, parameters such as density of ligating groups, oligomer steric barrier and reduction rates were found to be essential for the formation and stability of subnanometer Au particles. Without further treatment, the formed Au particles were active catalysts for the reduction of p-nitrobenzaldehyde by triethylsilane, forming an imine as the major coupling product. Deposition of the Au colloids onto silica, followed by thermal treatment to remove the organic groups resulted in subnanometer Au on silica, indicating this to be a promising method of fabricating subnanometer supported Au catalyst.

The importance of proximity of isolated TiOx cluster to Au surface for the formation of acetone in the selective oxidation of propane was investigated using a model system of Au particles decorated with mononuclear TiOx units dispersed in silica clusters. The results showed that no acetone was formed without TiOx, and its formation was more prominent on a sample containing a higher density of TiOx. Covering a Au/TiO2 catalyst with a layer of TiOx-containing silica changed the product selectivity from predominently propene to acetone. The data strongly supported the importance of isolated TiOx clusters near the Au surface in acetone formation, and suggested the relevance of Au-TiOx interface sites. Such interface sites might also be important in selective propene epoxidation that was coupled to CO oxidation in a H2O-methanol mixture. Using oxygen isotope labeling technique, it was found that the proximal source of oxygen in propene oxide was not from H2O but from O2. The observation was consistent with a methyl hydroperoxide intermediate, which could be formed by oxidation of a Ti methoxy at the Au-support interface.

The desire to attain high activity and selectivity achieved by systems in Nature has long been a source of inspiration for research in heterogeneous catalysis, and significant progress has been made. A summary is presented here of the progress in applying concepts in enzymes and cellular systems to develop artificial systems. The discussion is organized according to the length scale: dimensions of small molecules (~1 nm), protein (nm–μm), and cells (~μm). At the smallest dimension, the focus is on the active site, and effects observed include functional group cooperation, substrate partitioning, site isolation, transition state stabilization, and pK shifts. At the intermediate dimension of a protein, effects observed include size exclusion, steric constraint, and docking and induced fit. Interestingly, the oscillation phenomenon observed in artificial systems, which is due to collective behavior of atoms, is not observed in natural systems. At the largest, cellular scale, processes of interest include cascade reaction and tandem reactions, and metabolon is one natural system to emulate. There are interesting but nascent developments to emulate phenomena such as self-healing, stimuli-responsiveness, reaction coupling, and designed hierarchical distribution of pores and channels across all scales. Much could be gained if catalysts can be designed to incorporate these properties. .

Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping.

A comprehensive low-NOx corrosion study consisting of pilot-scale combustion testing and laboratory retort exposure was performed. From the pilot-scale testing, the gas and deposit compositions in the lower furnace of utility boilers burning eight U.S. coals with a wide range of sulfur and chlorine contents were determined. These combustion conditions were then closely reproduced in a series of 1,000 h laboratory corrosion tests to evaluate the materials performance of different furnace-wall alloys and weld overlays at 399, 454, and 510°C (750, 850, and 950°F). Results of the laboratory study indicate that a typical dual-layered scale was formed on the metal surface from simultaneous oxidation/sulfidation due to the presence of sulfur in coal. A new corrosion mechanism is proposed here as “active sulfidation” to account for the accelerated corrosion attack on furnace walls resulting from the presence of chlorine in coal. The mechanism involves the conversion of iron sulfide (FeS) in the corrosion scale to...

A lithium sulfide-reduced graphene oxide nanocomposite (Li2S-rGO) was synthesized and evaluated as the cathode material and Li source for the assembly of Li-S batteries. The composite, with a unique 3-D pocket structure, was synthesized by a combination of facile solution chemistry and thermal treatment. The as-prepared Li2S-rGO nanocomposites were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy, which showed 20–40 nm Li2S particles homogeneously dispersed between reduced graphene oxide sheets. Li2S contents as high as ∼66% could be obtained. When used with an electrolyte containing LiNO3 and polysulfide, the Li2S-rGO nanocomposites exhibited a high initial capacity of 982 mAh g−1 Li2S. However, there was noticeable capacity fade in subsequent cycles, probably due to polysulfide dissolution and the shuttle mechanism, but a capacity of 315 mAh g−1 could still be obtained after 100 cycles, with 90–95% coulomb efficiency. The effect of polysulfide additive in the electrolyte on the activation of Li2S in the first delithiation step was discussed.

Organosilicon compounds, in the form of cubic metallasiloxanes, cage-like silsesquioxanes, macromolecular nanocages, and flexible structures such as dendrimers and linear metallsiloxanes, have found useful applications as catalysts, ligands for metal complexes, and catalyst supports. Illustrative examples of these are presented. The well-defined structures of these compounds make them particularly suitable as molecular analogues of zeolites or silica-supported catalysts. A unique feature of many of these compounds is the presence of flexible siloxane bonds, which accommodate large fluctuations in the framework geometry, reminiscent of the adaptability of enzymes to conformational changes, and distinguish siloxane containing materials from carbon based synthetic materials. New preparative pathways and the use of the versatile silyl ester as a protection group have greatly expanded synthetic possibilities, pointing to the possibility of assembling these structures to form multifunctional catalytic structures. Some nanocage structures, with functionalities organized in close proximity, exhibit nanoconfinement effects.

A thermally responsive membrane separator, suitable for use in non-aqueous electrolytes, was constructed by grafting a UCST polymer, poly(sulfobetaine), onto graphene oxide sheets. When heated from 20 to 80 °C, it decreased the specific storage capacity of the electrode for Li by >50% reversibly, compared to 30% increase without polymer modification.

The effect a 45 atom-thick overlayer of aluminum oxide, deposited by atomic layer deposition, was investigated on a 2.5 wt.% Pd/Al 2 O 3 catalyst in which the Pd nanoparticles were encapsulated by the support consequent to the preparation method. The overlayer suppressed the activity for oxidative dehydrogenation of ethane, but it also effectively prevented metal sintering and suppressed coking for reactions at high temperatures. On the catalyst with the alumina overlayer, a steady activity was observed even at 600 °C and above when the gaseous oxygen was completely consumed, while attaining 70% selectivity for ethene at 38% conversion, versus 10% selectivity at comparable conversions without the overlayer. The overlayer preferentially deposited on edge Pd atoms, as indicated by preferentially suppression of the CO chemisorption peak at 2056 cm −1 , which are responsible for coking. The high ethene selectivity at 675 °C could be due to coupled homogeneous and heterogeneous reactions at the high temperature, together with phase change of PdO to Pd.

Mild calcination in ozone of a (POSS)-Sn-(POSS) complex grafted on silica generated a heterogenized catalyst that mostly retained the tetrahedral coordination of its homogeneous precursor, as evidenced by spectroscopic characterizations using EXAFS, NMR, UV–vis, and DRIFT. The Sn centers are accessible and uniform and can be quantified by stoichiometric pyridine poisoning. This Sn-catalyst is active in hydride transfer reactions as a typical solid Lewis acid. However, the Sn centers can also create Bronsted acidity with alcohol by binding the alcohol strongly as alkoxide and transferring the hydroxyl H to the neighboring Sn–O–Si bond. The resulting acidic silanol is active in epoxide ring opening and acetalization reactions.

A comprehensive fireside corrosion study has been performed to gain further understanding of the corrosion mechanisms operating in coal-fired utility boilers. Nine commercial coals from eight coal mines, representing a wide range of coal chemistry, were selected for this study. Combustion of these coals was carried out in a 160 KWth pilot-scale combustion facility that closely simulated the actual conditions of staged combustion in utility boilers. During the pilot-scale testing, gas and deposit samples were collected and analyzed online via in-furnace probing through sampling ports at elevations corresponding to the lower furnace and superheater locations. The in-furnace gas measurements identified the coexistence of reducing and oxidizing species in the gas phase, revealing the non-equilibrium nature of the combustion products. The amounts of sulfur and chlorine released to the gas phase as sulfur and chlorine-bearing species in both the reducing and oxidizing zones were linearly proportional to the amount of total sulfur and chlorine in coal, independent of their original forms. Furthermore, thermodynamics and kinetics of the sulfur and chlorine gas-phase and gas–solid reactions were considered. Based on comparison of the calculated and observed results, a new ash deposition mechanism is proposed.

Surface species formed in CH4 activation over Co–ZSM-5 were monitored by in situ DRIFT spectroscopy. IR absorption bands assigned to adsorbed methoxide, formate and polyoxymethylene were detected. The similarities in the IR bands and their evolution during He purge after reactions conducted under anaerobic and aerobic conditions suggested that Cannizzaro disproportionation of formaldehyde is a significant reaction pathway. This was verified when water was found to react with a surface species to form adsorbed formate. Continued formation of surface formate was observed during purging in He which indicated substantial surface storage of formaldehyde as polyoxymethylene.

Two types of dendrimers with AB2 branching, one with acyloxysilanes at the branching position (V type) and the other at the non-branching position (Y type), were synthesized using hydrosilylation with chlorosilanes followed by heterofunctional condensation with olefin-functional carboxylic acids, and examined as readily degradable template materials. The V type dendrimer was much more susceptible to ligand redistribution with chlorosilanes during preparation, whereas the Y type was less. The acyloxysilane linkages in these dendrimers could be cleaved readily by alcoholysis or hydrolysis on demand, making for suitable templates.

A tetrahedral stannasilsesquioxane complex was synthesized as a racemic mixture using Sn(O(i)Pr)4 and silsesquioxanediol, and its structure was confirmed with X-ray crystallography, NMR, and EXAFS. The complex was a Lewis acid, and both anti and syn-binding with Lewis bases were possible with the formation of octahedral Sn complexes. It was also a Lewis acid catalyst active for epoxide ring opening and hydride transfer.