Competitive Occupation Research Articles

Discovery of asymmetric distribution of fine particles in fluidization using signal deflection reconstruction measurement

Bubbles in fluidization contribute to efficient gas–solid interaction and excellent transfer behavior. The fines addition effectively improves fluidization quality by prioritizing bubble control. Our study delves into the dynamic behavior of these added fines through cold-flow fluidization experiments, employing coarse glass particle (Geldart Group B, 186 μm in diameter) with varying contents of fines (Geldart Group A, 60 μm in diameter). To overcome the challenge of measuring the solid volume fractions of individual components in this bi-disperse system, a novel measurement technology, coupled with an optical fiber probe and signal deflection reconstruction method, is established. This technology could sensitively capture the preferential entry of fines into bubbles, leading to an asymmetric distribution of fines between bubbles and emulsion phase. Furthermore, our proposed flux mode, considering both the capability to maintain mono-disperse phase segregation and the competitive occupation of bi-disperse particles through bubble interface, effectively describes the observed asymmetry.

Enhanced Oxide Ion Conductivity by Ta Doping of Ba3Nb1-xTaxMoO8.5.

Significant oxide ion conductivity has previously been reported for the Ba3M'M″O8.5 family (M' = Nb5+, V5+; M″ = Mo6+, W6+) of cation-deficient hexagonal perovskite derivatives. These systems exhibit considerable structural disorder and competitive occupation of two distinct oxygen positions (O3 site and O2 site), enabling two-dimensional (2D) ionic conductivity within the ab plane of the structure; higher occupation of the tetrahedral O3 site vs the octahedral O2 site is known to be a major factor that promotes oxide ion conductivity. Previous chemical doping studies have shown that substitution of small amounts of the M' or M″ ions can result in significant changes to both the structure and ionic conductivity. Here, we report on the electrical and structural properties of the Ba3Nb1-xTaxMoO8.5 series (x = 0.00, 0.025, 0.050, 0.100). AC impedance measurements show that substitution of Nb5+ with Ta5+ leads to a significant increase in low-temperature (<500 °C) conductivity for x = 0.1. Analysis of neutron and X-ray diffraction (XRD) data confirms that there is a decrease in the M1O4/M1O6 ratio upon increasing x from 0 to 0.1 in Ba3Nb1-xTaxMoO8.5, which would usually coincide with a lowering in the conductivity. However, neutron diffraction results show that Ta doping causes an increase in the oxide ion conductivity as a result of longer M1-O3 bonds and increased polyhedral distortion.

Mechanisms associated with the separation of phenols from complex coexisting systems

Phenols are recognized as one of the major hazardous organic compounds in industrial wastewater. However, the effects of the coexisting substances on the elimination of the phenolic pollutants were less explored. Herein, we have systematically evaluated the adsorption processes of hydroquinone with respect to three adsorbents in acid, salt, and homolog systems. Our results demonstrated that low concentrations of coexisting acids could benefit the adsorption process with a maximum promotion rate of 143.4% (Qe from 74.3 to 180.9 mg/g), while high concentration of lactic acid resulted in considerable inhibition to St-DVB-nitro with a maximum inhibitory rate to 72.8% (Qe=20.2 mg/g). The coexisting salts exhibited a potentiation effect with a maximum promotion efficiency of 105.9% (Qe=153.0 mg/g). Competitive binding to adsorption sites could be observed in homolog coexisting system, where p-nitrophenol served as the dominant adsorbent and the hydroquinone adsorption capacity were only maintained at 45.4% (Qe=33.7 mg/g). On basis of the coexisting and preloading systems study, KCl could increase the force of mass transfer by salting-out effect and cation synergistic effect to promote the adsorption. Meanwhile, preloading experiments confirmed the competitive occupation effect of lactic acid and p-nitrophenol on the adsorption site, and the more hydrophobic p-nitrophenol could even desorbed hydroquinone (desorption rate 19.5–22.2%). This work on the interactions among phenols, coexisting factors and solid interfaces will guide the actual phenols wastewater treatment.

Lanthanum activated palygorskite for selective phosphate separation from aqueous media: Comprehensive understanding of adsorptive behavior and mechanism affected by interfering substances

Eutrophication problem in surface waterbodies has attracted increasing attention. Herein, raw palygorskite (PAL) was activated by lanthanum engineering in alkaline surrounding for phosphate removal, and alkaline etching modified its structure and facilitated phosphate migration from bulk solution to active sites. Results indicated that stable and satisfactory phosphate capturing was maintained by as-prepared material within a wide pH range (3–9) and the disturbance of co-existing substances (Cl-, NO3–, HCO3–, SO42–, F- and HA). Further investigation on the role of interfering species in overall adsorption process indicated that phosphate capturing was accelerated rather than hindered at the initial hours, while the ultimate captured amount decreased owing to their competitive occupation on La active sites. Kinetic study suggested the chemisorption of phosphate and isotherm investigation illustrated the multilayer coverage of phosphate on the heterogeneous surface. Thermodynamic study implied spontaneous and endothermic process of phosphate uptake on La-PAL, and cyclic desorption-adsorption experiments demonstrated feasible regeneration and reuse of La-PAL for phosphate separation. Materials characterization demonstrated the formation of amorphous La-O-P inner-sphere complex through ligands exchange (i.e., –CO3–, –OH), whereas the interference of co-existing substances by competitive occupation and overlap on active sites was indicated. The present work could provide comprehensive insight into the role of interfering substances in phosphate adsorption on functionalized materials.

Potassium supply and adsorption capacity changes in a Chinese subtropical paddy soil chronosequence

ABSTRACT An accurate assessment of the effect of long-term rice cultivation on K-supplying capacity and adsorption characteristics of paddy soils has theoretical and practical significance for rational application of K fertilizers. We measured changes in basic soil properties and K adsorption isotherms in a representative subtropical paddy soil chronosequence in Southern China. Results showed that mean water dissolvable K and non-exchangeable K contents of paddy soils (27.0 and 184.8 mg kg−1) were higher than those of original soils (15.5 and 169.5 mg kg−1), but the mean exchangeable K contents showed the opposite trend (paddy soils, 37.1 mg kg−1; original soils, 52.5 mg kg−1). Long-term paddy cultivation caused reduced K-supplying capacity and K+ adsorption capacity of paddy soils in the red soil regions, which was attributed to the rapid loss of sorbents (e.g. Fed and clay) by leaching and the competitive occupation of sorption sites by the accumulated soil organic matter. The promotion of sustainable and balanced K fertilizer inputs and appropriate increase in short-term applications of K fertilizer (K fertilizer input > K output from harvest) during application of N and P fertilizers to paddy soils were necessary to maintain the K-supplying capacity of soils and the crop yield.

Formation Kinetics of the Mixed Cyclopentane—Carbon Dioxide Hydrates in Aqueous Sodium Chloride Solutions

Hydrate formation from cyclopentane (CP) and carbon dioxide was measured at 281 K by powder X-ray diffraction (PXRD) and macroscopic methods. The effect of initial pressure and CP mass fraction in liquid phase was analyzed. The results showed that hydrate formation was assumed to start with the nucleation of the mixed CP-CO2 hydrate with small fraction of CO2 followed by a large continuous CO2 adsorption. Initial pressure was found to have a positive correlation with the total CO2 consumptions when the initial pressure was below 2.5 MPa. However, the total CO2 consumptions dropped by over a half as the initial pressure was 3.0 MPa. PXRD revealed that all the hydrate samples formed at different initial pressures were structure II. The CO2 consumptions were assumed to be inhibited by the competitive occupation of 51264 cages between CP and CO2 molecules when the initial pressure was above 2.5 MPa. The CO2 consumptions were also found to be reduced as the CP mass fraction was above 0.25. An excess of CP molecules was not assumed to strengthen the formation of the mixed CP-CO2 hydrates at the initial stage, but increased the thickness of liquid CP film at aqueous brine and hydrate particles, which increased the diffusion resistance of CO2 molecules. Therefore, the suitable initial pressure and the CP mass fraction for the mixed CP-CO2 hydrate formation should be around 2.5 MPa and 0.2, respectively.

In situ quantitative determination of the intermolecular attraction between amines and a graphene surface using atomic force microscopy

The adsorption of pollutants on carbonaceous environmental media has been widely studied via batch sorption experiments and spectroscopic characterization. However, the molecular interactions between pollutants and interfacial sites on carbonaceous materials have only been indirectly investigated. To comprehend the adsorption mechanisms in situ, we applied atomic force microscopy force spectroscopy (AFM-FS) to quantitatively determine the molecular interactions between typical amines (methylamines and N-methylaniline) and the surface of highly oriented pyrolytic graphite (HOPG), which was supported by the single molecule interaction derived from density functional theory and batch adsorption experiments. This method achieved direct and in situ characterization of the molecular interactions in the adsorption process. The molecular interactions between the amines and the adsorption sites on the graphite surface were affected by pH and peaked at pH 7 due to strong cation-π interactions. When the pH was 11, the attractions were weak due to a lack of cation-π interaction, whereas, when the pH was 3, the competitive occupation of hydronium ions on the surface reduced the attraction between the amines and HOPG. Based on AFM-FS, the single molecule force of methylamine and N-methylaniline on the graphite surface was estimated to be 0.224 nN and 0.153 nN, respectively, which was consistent with density functional theory (DFT) calculations. This study broadens our comprehension of cation-π interactions between amines and electron-rich aromatic compounds at the micro/nanoscale.

Free-volume evolution in Pr3+-activated Ga/Te-modified glassy arsenic selenides

Free-volume evolution processes in As2Se3 glasses connected with subsequent stages of their modification (Ga-codoping, Te-modification, and Pr3+-doping) are studied employing positron annihilation lifetime (PAL) spectroscopy. Ga-codoping and rare-earth (RE)-doping effects are considered within the formal valence shell model, assuming fourfold coordination for metallic co-dopants. The PAL response on Ga-codoping in As2Se3 glass is associated with an increase in the defect-related positron lifetime τ2 and a decrease in the I2 intensity, meaning agglomeration of the PAL-responsible voids. The effect of Te-modification (in order to lower the phonon energy) testifies in favor of the stretching fragmentation process in the void structure resulting in essentially enhanced positron trapping rate in free-volume defects κd. Under the subsequent stage of Pr3+-doping, free volume space is changed due to void agglomeration resulting in 10 % decrease in the positron trapping rate. This effect is ascribed to the competitive occupation of positron preferential annihilation sites in the glass by RE dopants.

Lupus IgG deposition causes arthritis but inhibits bone destruction through competitive occupation of FcγRI and reduced RANKL signalling.

ObjectivesBone destruction is a remarkable feature of inflammatory arthritis. It remains unknown why arthritis associated with the systemic autoimmune/inflammatory condition systemic lupus erythematosus (SLE) does not result in erosion and destruction. We aimed to determine the role of autoantibody in the pathogenesis of non‐erosive arthritis in SLE.MethodsWe analysed medical record of SLE patients, investigated whether autoantibody induces arthritis lacking bone destruction in animal models and determined whether SLE autoantibody inhibits osteoclastogenesis induced by RANKL in vitro experiments.ResultsWe found that arthritis lacking bone erosions is common in SLE patients and lupus‐prone mice. Intraarticular injection of lupus serum or IgG induces immune complex deposition and arthritis, but does not result in bone destruction. Deposition of IgG, monocytes/macrophages and TNF‐α is all required for the development of arthritis. Lupus serum or IgG inhibits RANKL‐induced differentiation of monocytes into osteoclast in a dose‐dependent manner. FcγR acts as co‐receptors for RANKL and is involved in osteoclastogenesis. Deficiency of FcγRII or FcγRIII does not affect osteoclastogenesis in the presence of SLE IgG. However, lupus IgG competes for FcγRI binding with RANKL, thereby reducing osteoclastogenesis.ConclusionObservations from this study demonstrate that IgG from SLE patients can induce arthritis and inhibits RANKL‐induced osteoclastogenesis through competitive occupation of FcγRI on monocytes/macrophages. This study improves the understanding of the pathophysiology of SLE‐associated arthritis and offers a protective mechanism (FcγRI inhibition) that may be targeted in other forms of autoimmune/inflammatory arthritis, such as RA, to prevent or limit bone erosion and inflammatory bone loss.

The impact of absorbents on ammonia recovery in a capacitive membrane stripping system

Although a capacitive membrane stripping system (CapAmm) has been demonstrated to be an efficient approach for ammonia removal and recovery in our previous reports, the influence of the ammonia absorbent used on CapAmm performance is not well understood. In this study, we clarify the role of particular ammonia absorbents (H2SO4, H3PO4, HNO3, HCl, H2CO3* and H2O) in the CapAmm process with regard to water desalination, ammonia removal and recovery and mass flux. While results of bench-scale studies indicated that absorbent type has little impact on salt removal efficiency, the majority of ammonia flowed to the recovery chamber followed by fixation as ammonium salts when acidic absorbents were used, with the application of the non-volatile absorbents, H2SO4 and H3PO4, resulting in maximum ammonia recovery (>70%). In the case of volatile acidic absorbents (HNO3 and HCl), inferior ammonia recovery efficiency was observed with the reduced recovery attributed mainly to water transfer across the hydrophobic gas membrane as a result of the water vapor partial pressure difference between catholyte and acid receiving solution. When H2CO3* and H2O were used as absorbents, back-diffusion of CO2 and NH3 occurred, most likely as a result of both competitive occupation of the gas membrane pores and a decrease in catholyte pH, with this back diffusion leading to a deterioration in net ammonia flux. In contrast to the unsatisfying recovery performance, economic evaluation suggests that use of H2CO3* and H2O as ammonia absorbents is more cost-effective compared to strong acid adsorbents as a result of the lower chemical costs and higher product revenues.

Inhibition of the Alanine-Serine-Cysteine-1 Transporter by BMS-466442.

Experiment and modeling were combined to understand inhibition of the alanine-serine-cysteine-1 (asc1) transporter. The structure-activity relationship (SAR) was explored with synthesis of analogues of BMS-466442. Direct target interaction and binding site location between TM helices 6 and 10 were confirmed via site directed mutagenesis. Computational modeling suggested the inhibitor binds via competitive occupation of the orthosteric site while also blocking the movement of TM helices that are required for transport.

Novel approaches to Neisseria meningitidis vaccine design.

A range of vaccines is available for preventing life-threatening diseases caused by infection with Neisseria meningitidis (meningococcus, Men). Capsule polysaccharide (CPS)-conjugate vaccines are successful prophylactics for serogroup MenA, MenC, MenW and MenY infections, and outer membrane vesicle (OMV) vaccines have been used successfully for controlling clonal serogroup MenB infections. MenB vaccines based on recombinant proteins identified by reverse vaccinology (Bexsero™) and proteomics (Trumenba™) approaches have recently been licensed and Bexsero™ has been introduced into the UK infant immunisation programme. In this review, we chart the development of these licensed vaccines. In addition, we discuss the plethora of novel vaccinology approaches that have been applied to the meningococcus with varying success in pre-clinical studies, but which provide technological platforms for application to other pathogens. These strategies include modifying CPS, lipooligosaccharide and OMV; the use of recombinant proteins; structural vaccinology approaches of designing synthetic peptide/mimetope vaccines, DNA vaccines and engineered proteins; epitope presentation on biological and synthetic particles; through vaccination with live-attenuated pathogen(s), or with heterologous bacteria expressing vaccine antigens, or to competitive occupation of the nasopharyngeal niche by commensal bacterial spp. After close to a century of vaccine research, it is possible that meningococcal disease may be added, shortly, to the list of diseases to have been eradicated worldwide by rigorous vaccination campaigns.

"Signal-on" photoelectrochemical sensing strategy based on target-dependent aptamer conformational conversion for selective detection of lead(II) ion.

A "signal-on" photoelectrochemical sensing strategy for selective determination of Pb(2+) is designed on the basis of the combination of Pb(2+)-induced conformational conversion, the amplified effect of reduced graphene oxide (RGO) and resonance energy transfer between CdS quantum dots (QDs) and gold nanoparticles (AuNPs). The RGO/CdS/aptamer platform is constructed via a stepwise modification method, and characterized by electrochemical impedance spectroscopy. In the absence of Pb(2+), the AuNP-labeled DNA, as a signal quenching element, can be introduced by hybridization with aptamer on the surface of sensing platform, which quenches the photocurrent of QDs via an energy transfer process. Upon addition of Pb(2+), the aptamer is induced into a G-quadruplex structure, which can greatly hinder the hybridization between aptamer and AuNP-labeled DNA due to the competitive occupation of binding sites and steric effect, leading to the recovery of photocurrent. Under optimized conditions, this "signal-on" photoelectrochemical biosensor shows a linear relationship between photocurrent variation and the logarithm of Pb(2+) concentration in the range of 0.1-50 nM with a detection limit of 0.05 nM. Meanwhile, it also exhibits good selectivity for Pb(2+) over other interfering ions, and is successfully applied to the detection of Pb(2+) in environmental water samples. By substituting the aptamers with other sequences, this proposed strategy could be conveniently extended to detect different targets as versatile photoelectrochemical devices.

Effect of surfactant on the estimation by solid phase microextraction of bioavailable pyrene in soil samples

This study was focused on the effect of the presence of surfactant on the bioremediation efficacy and sensitivity of solid phase microextraction (SPME) in the pyrene-contaminated soil. Soils with 1.3 and 7.6% soil organic matter (SOM) were tested for biodegradation by microorganisms and extracted by aqueous solutions of the matrix used for SPME. For the biodegradation test, the presence of Triton X-100 at 5× CMC (critical micelle concentration) significantly enhanced pyrene removal for soil with lower SOM content (1.3%). However, this removal was insignificant for soil with higher SOM content (7.6%). The results may suggest that 5× CMC was not sufficient to improve significantly pyrene desorption for soil with higher SOM content. For the bioavailability test, in the absence of Triton X-100, SPME estimation of bioavailability in soils with indigenous or seeded microorganisms had an error range within 15%. However, with addition of Triton X-100, SPME estimations showed a significant decline (41 and 77%), in relation to their predicted values, for soil samples with SOM of 1.3 and 7.6%, respectively. The main reason for this underestimation is that micelle formation from the application of surfactant impacted the concentration of dissolved pyrene, rather than competitive site occupation between pyrene and surfactant molecules for SPME fiber. Thus, if soil samples contain surfactant, SPME would significantly underestimate bioavailability and risk level of PAH-contaminated sites.

Trapping of hydride forming elements within miniature electrothermal devices. Part 3. Investigation of collection of antimony and bismuth on a molybdenum foil strip following hydride generation

The interaction of stibine and bismuthine with a surface of bare and modified (Pt, Ir and Rh) molybdenum foil strips was investigated by atomic absorption spectrometry with a miniature hydrogen flame atomizer. Different trapping behavior of both analytes was observed contrary to selenium and arsenic hydrides. Maximum trapping efficiency of Sb and Bi is achieved at lower temperatures of 650–750 °C and 500–600 °C, respectively. Absence of hydrogen in argon does not affect trapping of these elements, whereas trapping of As and Se is feasible only in the presence of hydrogen. All used modifiers inhibit trapping of Bi and Sb when their amount exceeds 30 μg. Collected Sb is completely released at temperatures above 2200 °C, whereas a temperature of 1 200 °C is sufficient for vaporization of Bi. Aerodynamic conditions of the injected gas near the molybdenum surface play the same role in trapping both analytes as for As and Se. Maximum trapping efficiencies are achieved at total gas flow rates of 60–70 ml min − 1 and with a capillary distance of 2 mm. Trapping of Sb is not influenced within the whole interferent mass range of 0–30 μg of As and Se, and 0–300 ng of Bi. Trapping of other analytes is affected by 1 to 2 orders of magnitude higher amounts of concomitant hydrides. According to thermodynamic calculations, the competitive occupation of active sites on the molybdenum surface by the AsO (g) and SbO (g) species and the formation of the inactive analyte–interferent diatomic BiSe (g) and AsSe (g) species can probably be the reason for these interference effects.

THE PURSUIT OF NEWNESS

The paper draws on research conducted in the late 1990s into the workplace cultures of London-based advertising agencies and the subjective identities of a group of young, largely male art directors and copywriters (Nixon 2003). The paper explores how these practitioners used the trope of creativity to describe the work they performed and considers what was at stake in their easy but insistent recourse to the term. It suggests that their extraordinary valorising of creativity was bound up with the extrapolation from quite small degrees of different-ness in the work they produced or strove to produce. In this sense, their cult of creativity was partly bound up with a ‘narcissism of minor differences’ in which creative teams sought to differentiate themselves from each other in the advertising that they generated. Furthermore, the valorisation of creativity was tied up less, in this sense, with making a client's product stand out – the manifest commercial reason for finding new ways of communicating with consumers – so much as with drawing attention to the creative teams in an intensely competitive occupation. The pursuit of newness also often came to be bound up with struggles over genres and genre hierarchies that themselves become coded in generational terms. Young creatives would ally themselves with ‘newness’ in order to challenge more established colleagues. We might read into this pursuit of newness and creativity, then, a strategy of distinction and position taking by differently placed practitioners over the accumulation of recognition and status and its conversion into tangible economic rewards. As such the cult of creativity amongst these creative people formed part of the cultivation of a distinct habitus in this ‘talent-led’ field of cultural production in which speaking the language and pursuing the signs of creativity was central to the successful shaping of an identity at work.

The Various Effects of Four H1-Antagonists on Serum Substance P Levels in Patients with Atopic Dermatitis

Antiallergic drugs have various actions against allergy-associated cells and molecules as well as antihistamic properties. We studied the effects of antiallergics on the serum levels of substance P. Patients with atopic dermatitis were treated with one of four oral H1-antagonists for 14 days, and the serum level of substance P was measured before and after treatment in parallel with several atopic severity markers. Olopatadine significantly decreased the substance P level. This is in accordance with its known downmodulatory effect on tachykinin release. In contrast, cetiridine and fexofenadine unexpectedly increased the substance P level. In patients administered cetiridine, the blood severity markers for atopic dermatitis, including lactate dehydrogenase, eosinophil number, and the soluble forms of IL-2R, E-selectin, VCAM-1 and ICAM-1 were reduced after the treatment. Therefore, the elevation of SP was unrelated to the deterioration of atopic dermatitis but rather associated with improvement. Our study suggests that antiallergics can be divided into substance P-increasing and -decreasing types and raises the possibility that the increment of substance P by the former type is caused by the competitive occupation of substance P receptors.

Promotion of Catalytic Activity and Suppression of Deactivation by Solvent Addition in the Hydrotreating of Atmospheric Residue

The effect of addition of several solvents on atmospheric residue (AR) hydrotreating was examined in the autoclave test. Higher hydrodesulfurization (HDS) activity was obtained by adding solvents in the order of H2O > light cycle oil (LCO) > tetralin > none (base) > 1-MN > phenol, using the same volume of solvent. The amount of deposited coke on the catalyst was reduced with all solvents. Larger amounts of tetralin enhanced HDS activity, but tetralin was still inferior to water for the enhancement of HDS in the same molar amounts. The specific effects of H2O were confirmed through the activity test. The amount of deposited coke on catalyst with tetralin was similar to that of H2O. Enhancement of asphaltene desorption reduces coke formation on the catalyst whereas the hydrogenative conversion of solvents with sulfur species in AR may indicate competitive occupation on the active sites. Solvents were not only hydrogenated but also contributed to inhibition of HDS when remaining for long periods on the active sites. Consequently, the inhibition effects of the solvents were considered based on the conversion and evaluation results. H2O enhances the desorption of asphaltene and desulfurized products from the catalyst compared with the other solvents. The remarkable effects of H2O addition are due to remaining on the active sites for short periods, without inhibiting the HDS activity.

The Bay Shrimpers of Texas: Rural Fishermen in a Global Economy.

Shrimpers who fish the shallow coastal waters of Texas fight a constant battle for survival--contending with shrimpers who fish the deeper gulf waters, competing with weekend sportsmen, wrangling with government regulations, and dodging environmentalists' incriminations. Add competition from the international market, an ominous threat frequently overlooked by bay fishermen, and the shrimpers; chances of winning--at least with their current lifestyle intact--are slim. In The Bay Shrimpers of Texas, Lee Maril explores the successes and failures of the shrimpers who prowl remote bays, rivers, and estuaries for their livelihoods. Through random sample surveys of fishermen, participant observation, and historical analysis, he examines the political, economic, and social realities confronting the shrimpers and their families. Legal and environmental constraints, price instability, work hazards and benefits (only one percent of the shrimpers surveyed had health insurance), rivalry with gulf and sport shrimpers, and conflict with Vietnamese refugees are all factors that affect the outlook for shrimping. Portraying the shrimpers' lives on land and water, Maril describes their boats, equipment, and various fishing strategies (both legal and illegal) used to survive in an increasingly competitive occupation. He gives an in-depth and personal look at an industry that in many ways has changed little over the last century and in others has haphazardly evolved as it enters into a ruthlessly competitive world marketplace. The prospects for bay fishing--a vital part of the cultural identity and tradition of many small coastal towns--are uncertain. By examining the past and clearing up misperceptions and myths, Maril provides valuable insight into not just the future survival or demise of one industry in a global economy, but the future of small business as a whole.

Surface structure dependence of reactive chemisorption of acetonitrile on single-crystal Pt surfaces

Acetonitrile (AN) is reductively chemisorbed at Pt at the beginning of the “double-layer” potential region in the cyclic voltammogram for this electrode material, taken between 0.06 V and ca. 0.80 V vs. RHE. In this adsorbed state, it then undergoes almost reversible stages of reoxidation or re-reduction, and slower further reduction over the underpotential deposition (UPD) H region. In this respect, Pt, bearing a sub-monolayer of chemisorbed acetonitrile, was one of the first “chemically modified electrodes” to be discovered. These processes, previously studied at polycrystalline Pt, were investigated by means of cyclic voltammetry at the (111), (110) and (100) planes, together with the (311) stepped plane, of well characterized single-crystal Pt surfaces which exhibit, in the absence of adsorbed acetonitrile, the characteristically distinguished cyclic voltammograms demonstrated by Clavilier for clean, well prepared surfaces. Complementary information on the reductive chemisorption of AN and competitive occupation of H sites is provided by recording of adsorption current transients when AN is added, at controlled potential, to an initially AN-free solution. In the UPD H region, the transient currents contain a component due to the “anodic H desorption effect”. The chemisorption and surface reactivity behaviour of acetonitrile at these crystal planes is found to be very specific to the geometry of the surfaces and provides one of the clearest examples of such surface specificity in electrochemical surface science. Similarities to and contrasts with the surface-specific behaviour of the four crystal planes with respect to UPD H behaviour and HSO 4 − or ClO 4 − anion adsorption are observed and their significance is discussed.