In situ studies of titania-supported Au shell-Pd core nanoparticles for the selective aerobic oxidation of crotyl alcohol

The thermal evolution of titania-supported Au shell–Pd core bimetallic nanoparticles, prepared via colloidal routes, has been investigated by in situ XPS, DRIFTS, EXAFS and XRD and ex situ HRTEM. As-prepared nanoparticles are terminated by a thin (∼5 layer) Au shell, encapsulating approximately 20 nm diameter cuboctahedral palladium cores, with the ensemble stabilised by citrate ligands. The net gold composition was 40 atom%. Annealing in vacuo or under inert atmosphere rapidly pyrolyses the citrate ligands, but induces only limited Au/Pd intermixing and particle growth <300 °C. Higher temperatures promote more dramatic alloying, accompanied by significant sintering and surface roughening. These changes are mirrored by the nanoparticle catalysed liquid phase selective aerobic oxidation of crotyl alcohol to crotonaldehyde; palladium surface segregation enhances both activity and selectivity, with the most active surface alloy attainable containing ∼40 atom% Au.

Synthesis of CuS and CuS/ZnS core/shell nanocrystals for photocatalytic degradation of dyes under visible light

High quality CuS and CuS/ZnS core/shell nanocrystals (NCs) were synthesized in a large quantity using a facile hydrothermal method at low temperatures of 60 C and evaluated in the photodegradation of Rhodamine B (RhB) under visible light irradiation. Synthesis time plays an important role in controlling the morphology, size and photocatalytic activity of both CuS and CuS/ZnS core/shell NCs which evolve from spherical shaped particles to form rods with increasing reaction time, and after 5 h resemble "flower" shaped morphologies in which each "flower" is composed of many NCs. Photocatalytic activity originates from photo-generated holes in the narrow bandgap CuS, with encapsulation by large bandgap ZnS layers used to form the core/shell structure that improves the resistance of CuS towards photocorrosion. Such CuS/ZnS core/shell structures exhibit much higher photocatalytic activity than CuS or ZnS NCs alone under visible light illumination, and is attributed to higher charge separation rates for the photo-generated carriers in the core/shell structure. © 2013 Elsevier B.V.

Cellular uptake of ribonuclease A-functionalised core-shell silica microspheres

Analysis of protein function in a cellular context ideally requires physiologically representative levels of that protein. Thus conventional nucleic acid-based transfection methods are far from ideal owing to the over expression that generally results. Likewise fusions with protein transduction domains can be problematic whilst delivery via liposomes/nanoparticles typically results in endosomal localisation. Recently polymer microspheres have been reported to be highly effective at delivering proteins into cells and thus provide a viable new alternative for protein delivery (protein transduction). Herein we describe the successful delivery of active ribonuclease A into HeLa cells via novel polymer core-silica shell microspheres. Specifically, poly(styrene-co-vinylbenzylisothiouronium chloride) core particles, generated by dispersion polymerisation, were coated with a poly(styrene-co-trimethoxysilylpropyl methacrylate) shell. The resultant core-shell morphology was characterised by transmission electron, scanning electron and fluorescence confocal microscopies, whilst size and surface charge was assessed by dynamic light scattering and zeta-potential measurements, respectively. Subsequently ribonuclease A was coupled to the microspheres using simple carbodiimide chemistry. Gel electrophoresis confirmed and quantified the activity of the immobilised enzyme against purified HeLa RNA. Finally, the polymer-protein particles were evaluated as protein-transduction vectors in vitro to deliver active ribonuclease A to HeLa cells. Cellular uptake of the microspheres was successful and resulted in reduced levels of both intracellular RNA and cell viability.

Cost-effective and eco-friendly synthesis of novel and stable N-doped ZnO/g-C3N4 core-shell nanoplates with excellent visible-light responsive photocatalysis

N-doped ZnO/g-C3N4 hybrid core–shell nanoplates have been successfully prepared via a facile, cost-effective and eco-friendly ultrasonic dispersion method for the first time. HRTEM studies confirm the formation of the N-doped ZnO/g-C3N4 hybrid core–shell nanoplates with an average diameter of 50 nm and the g-C3N4 shell thickness can be tuned by varying the content of loaded g-C3N4. The direct contact of the N-doped ZnO surface and g-C3N4 shell without any adhesive interlayer introduced a new carbon energy level in the N-doped ZnO band gap and thereby effectively lowered the band gap energy. Consequently, the as-prepared hybrid core–shell nanoplates showed a greatly enhanced visible-light photocatalysis for the degradation of Rhodamine B compare to that of pure N-doped ZnO surface and g-C3N4. Based on the experimental results, a proposed mechanism for the N-doped ZnO/g-C3N4 photocatalyst was discussed. Interestingly, the hybrid core–shell nanoplates possess high photostability. The improved photocatalytic performance is due to a synergistic effect at the interface of the N-doped ZnO and g-C3N4 including large surface-exposure area, energy band structure and enhanced charge-separation properties. Significantly, the enhanced performance also demonstrates the importance of evaluating new core–shell composite photocatalysts with g-C3N4 as shell material.

Situational Script Management of Business Processes with Changeable Structure

In the presented work the problem of management business-processes with changeable structure is considered and situational based approach to its decision is offered. The approach is based on situational model of management business-process according to which process is represented as a set of situations. The script defining necessary actions is connected with each situation. Management of process is carried out by means of the rules formalizing functional requirements to processes.

Kerr nonlinear switching in a core-shell microspherical resonator fabricated from the silicon fiber platform

We investigate the Kerr nonlinearity in a core-shell microspherical resonator fabricated from a silicon fiber. By exploiting the ultrafast wavelength shifting, sub-picosecond modulation is demonstrated. © OSA 2015.

Combined effects of short-term exposure to elevated CO2 and decreased O2 on the physiology and energy budget of the thick shell mussel Mytilus coruscus

Hypoxia and ocean acidification are two consequences of anthropogenic activities. These global trends occur on top of natural variability. In environments such as estuarine areas, short-term acute pH and O2 fluctuations are occurring simultaneously. The present study tested the combined effects of short-term seawater acidification and hypoxia on the physiology and energy budget of the thick shell mussel Mytilus coruscus. Mussels were exposed for 72 h to six combined treatments with three pH levels (8.1, 7.7 and 7.3) and two dissolved oxygen (DO) levels (2 mg/L, 6 mg/L). Clearance rate (CR), food absorption efficiency (AE), respiration rate (RR), ammonium excretion rate (ER), O:N ratio and scope for growth (SFG) were significantly reduced, and faecal organic dry weight ratio (E) was significantly increased at low DO. Low pH did not lead to a reduced SFG. Interactive effects of pH and DO were observed for CR, E and RR. Principal component analysis (PCA) revealed positive relationships among most physiological indicators, especially between SFG and CR under normal DO conditions. These results demonstrate that Mytilus coruscus was sensitive to short-term (72 h) exposure to decreased O2 especially if combined with decreased pH levels. In conclusion, the short-term oxygen and pH variation significantly induced physiological changes of mussels with some interactive effects.

Physiological energetics of the thick shell mussel Mytilus coruscus exposed to seawater acidification and thermal stress

Anthropogenic CO2 emissions have caused seawater temperature elevation and ocean acidification. In view of both phenomena are occurring simultaneously, their combined effects on marine species must be experimentally evaluated. The purpose of this study was to estimate the combined effects of seawater acidification and temperature increase on the energy budget of the thick shell mussel Mytilus coruscus. Juvenile mussels were exposed to six combined treatments with three pH levels (8.1, 7.7 and 7.3) * two temperatures (25 °C and 30 °C) for 14 d. We found that clearance rates (CRs), food absorption efficiencies (AEs), respiration rates (RRs), ammonium excretion rates (ER), scope for growth (SFG) and O:N ratios were significantly reduced by elevated temperature sometimes during the whole experiments. Low pH showed significant negative effects on RR and ER, and significantly increased O:N ratios, but showed almost no effects on CR, AE and SFG of M. coruscus. Nevertheless, their interactive effects were observed in RR, ER and O:N ratios. PCA revealed positive relationships among most physiological indicators, especially between SFG and CR under normal temperatures compared to high temperatures. PCA also showed that the high RR was closely correlated to an increasing ER with increasing pH levels. These results suggest that physiological energetics of juvenile M. coruscus are able to acclimate to CO2 acidification with a little physiological effect, but not increased temperatures. Therefore, the negative effects of a temperature increase could potentially impact the ecophysiological responses of M. coruscus and have significant ecological consequences, mainly in those habitats where this species is dominant in terms of abundance and biomass.

História da matemática e teatro nas aulas sobre Teorema de Tales: um script proposto

This study will present the results of an investigation of how the history of mathematics and theater can contribute to the construction of mathematical knowledge of students in the 9th year of elementary school, through the experience, preparation and execution of a play, beyond presentation of the script. This brings a historical approach, defining space and time of events, putting the reader and viewer to do the route in the biography of Thales of Miletus (624-546 a.C), creating situations that led to the study and discussion of the content related to the episode possible to measure the height of the pyramid Khufu and the Theorem of Thales. That said, the pedagogical proposal implemented in this work was based on theoretical and methodological assumptions of the History of Mathematics and Theatre, drawing upon authors such as Mendes (2006), Miguel (1993), Gutierre (2010), Desgrandes (2011), Cabral (2012). Regarding the methodological procedures used qualitative research because it responds to particular issues, analyzing and interpreting the data generated in the research field. As methodological tools we have used participant observation, the questionnaire given to the students, field diary and dissertativos texts produced by students. The processing and analysis of data collected through the questionnaires were organized, classified and quantified in tables and graphs for easy viewing, interpretation, understanding and analysis of data. Data analysis corroborated our hypothesis and contributed to improving the use and display of the play as a motivating activity in mathematics classrooms. Thus, we consider that the script developed, ie the educational product proposed will bring significant contributions to the teaching of Mathematics in Primary Education

Shell flux and oxygen isotope data of North Atlantic foraminifera

We present an almost 3 year long time series of shell fluxes and oxygen isotopes of left-coiling Neogloboquadrina pachyderma and Turborotalita quinqueloba from sediment traps moored in the deep central Irminger Sea. We determined their response to the seasonal change from a deeply mixed water column with occasional deep convection in winter to a thermally stratified water column with a surface mixed layer (SML) of around 50 m in summer. Both species display very low fluxes during winter with a remnant summer population holding out until replaced by a vital population that seeds the subsequent blooms. This annual population overturning is marked by a 0.7 per mill increase in d18O in both species. The shell flux of N. pachyderma peaks during the spring bloom and in late summer, when stratification is close to its minimum and maximum, respectively. Both export periods contribute about equally and account for >95% of the total annual flux. Shell fluxes of T. quinqueloba show only a single broad pulse in summer, thus following the seasonal stratification cycle. The d18O of N. pachyderma reflects temperatures just below the base of the seasonal SML without offset from isotopic equilibrium. The d18O pattern of T. quinqueloba shows a nearly identical amplitude and correlates highly with the d18O of N. pachyderma. Therefore T. quinqueloba also reflects temperature near the base of the SML but with a positive offset from isotopic equilibrium. These offsets contrast with observations elsewhere and suggest a variable offset from equilibrium calcification for both species. In the Irminger Sea the species consistently show a contrast in their flux timings. Their flux-weighted delta d18O will thus dominantly be determined by seasonal temperature differences at the base of the SML rather than by differences in their depth habitat. Consequently, their sedimentary delta d18O may be used to infer the seasonal contrast in temperature at the base of the SML.

(Table 1) Shell mass and chemistry of Globigerinoides sacculifer

Using bathymetric transects of surface sediments underlying similar sea surface temperatures but exposed to increasing dissolution, we examined the processes which affect the relationship between foraminiferal Mg/Ca and d18O. We found that Globigerinoides saccculifer calcifies over a relatively large range of water depth and that this is apparent in their Mg content. On the seafloor, foraminiferal Mg/Ca is substantially altered by dissolution with the degree of alteration increasing with water depth. Selective dissolution of the chamber calcite, formed in surface waters, shifts the shell's bulk Mg/Ca and d18O toward the chemistries of the secondary crust acquired in colder thermocline waters. The magnitude of this shift depends on both the range of temperatures over which the shell calcified and the degree to which it is subsequently dissolved. In spite of this shift the initial relationship between Mg/Ca and d18O, determined by their temperature dependence, is maintained. We conclude that paired measurements of d18O and Mg/Ca can be used for reconstructing d18Owater, though care must be taken to determine where in the water column the reconstruction applies.

Le script de l'intervention policière auprès des personnes en état mental perturbé : déroulement et facteurs de l'usage de force par les policiers

Travail dirigé présenté à la Faculté des études supérieures et postdoctorales en vue de l’obtention du grade de maîtrise ès sciences (M.SC) en criminologie, option sécurité intérieure

Le script de l'intervention policière auprès des personnes en état mental perturbé : déroulement et facteurs de l'usage de force par les policiers

Travail dirigé présenté à la Faculté des études supérieures et postdoctorales en vue de l’obtention du grade de maîtrise ès sciences (M.SC) en criminologie, option sécurité intérieure