Metal hollow sphere electrocatalysts

Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.     

Component fatty acids of marine fish liver oils

Summary 1. Two liver oils (Elasmobranch) fromCarcharias melanopterus andPristis cuspidatus, caught off the Madras coast are studied, and their component fatty acids are reported. 2. The mixed acids were separated into three groups (varying unsaturation) of acids, and their methylesters were fractionated. 3. The liver oils are found to belong to the fourth group of Tsujimoto’s classification of Elasmobranch fish liver oils.Carcharias melanopterus liver oil contains 31.1% unsaturated acids (myristic 3.1, palmitic 18.4, stearic 9.5, and 0.1% arachidic) and 68.9% unsaturated acids (C₁₆ 10.8, C₁₈ 19.7, C₂₀ 15.2, C₂₂ 17.1, C₂₄ 5.3%, and traces of C₁₄ monoethenoid).Pristis cuspidatus liver oil contains 36.9% saturated acids (myristic 1.2, palmitic 22.9, stearic 12.7, and arachidic 0.1%) and 67.1% unsaturated acids (C₁₆ 8.2, C₁₈ 28.5, C₂₀ 16.4, C₂₂ 5.2, C₂₄ 4.6%, and traces of C₁₄ monoethenoid). The unsaturations of the different groups of acids are almost of the same order. 4. The abnormal content of saturated acids can be explained by the process of bio-hydrogenation. The relatively less amount of saturated acids inCarcharias melanopterus liver oil along with its higher content of polyethylenic acids (C₂₀ and above) points strongly to the possible presence of intermediate types of fats among the four groups of Elasmobranch oils.     

Investigation of anti-corrosion behavior of waterborne organosilane–polyester coatings for AA6011 aluminum alloy

Thermal-cured, sol–gel derived, waterborne organosilane–polyester coatings (SiE) have been developed using methyltrimethoxysilane, 3-glycidoxytrimethoxysilane and polyester resin for corrosion protection of aluminum AA6011. The structural and morphological features of the coatings were analyzed by Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM). Results show that the coatings on aluminum were smooth, continuous and defect-free. Performance of the SiE coatings were investigated and compared with pure organosilane coating and polyester coating using potentiodynamic polarization studies, contact angle measurement and pencil hardness test. Results from polarization studies have shown that the SiE coated substrate (4.6–13.1 × 10⁻⁷ A/cm²) provided a better corrosion protection than the polyester coated substrate (7.8 × 10⁻⁶ A/cm²) due formation of aluminum–oxygen–silicon covalent bond at aluminum-coating interface. Furthermore, SiE coatings provided better hydrophobicity and hardness than the polyester coating.     

Investigation on dual corrosion performance of magnesium-rich primer for aluminum alloys under salt spray test (ASTM B117) and natural exposure

Magnesium-rich primers perform very well on outdoor exposure and actual test conditions, yet fail rapidly in accelerated corrosion testing (salt spray test - ASTM B117). To investigate the behavioral dichotomy, Mg-rich primers exposed to salt spray testing and natural weathering were characterized at periodic intervals. The results revealed the presence of a thin and porous magnesium hydroxide layer in primers exposed to salt spray, and in natural exposure, a thicker, protective magnesium carbonate layer was detected and characterized. Samples exposed to atmospheric carbon dioxide exhibit excellent corrosion resistance but salt spray conditions are not conducive to facilitate magnesium carbonate formation.     

ITER vacuum vessel: Design review and start of procurement process

The ITER vacuum vessel (VV) is one of the most critical components in the ITER project. It is on the critical path in the construction schedule and it is also a safety important class component (SIC), providing the first confinement barrier.As a result of reviews and the latest physics analyses, design requirements have been updated (e.g. ELM/VS coils) and a few design changes have to be implemented. This paper covers the updates of the VV vertical and horizontal EM load conditions during asymmetric VDEs, the design analysis of the ELM/VS coils and their interfaces to the VV, the blanket manifold design and the preparation of the technical specification in preparation for the procurement arrangement to be signed.     

An asymptotic solution for the surface magnetic field within the paraxial region of a circular cylinder with an impedance boundary condition

It is well-known that the high-frequency asymptotic evaluation of surface fields by the conventional geometrical theory of diffraction (GTD) usually becomes less accurate within the paraxial (close to axial) region of a source excited electrically large circular cylinder. Uniform versions of the GTD based solution for the surface field on a source excited perfect electrically conducting (PEC) circular cylinder were published earlier to yield better accuracy within the paraxial region of the cylinder. However, efficient and sufficiently accurate solutions are needed for the surface field within the paraxial region of a source excited circular cylinder with an impedance boundary condition (IBC). In this work, an alternative approximate asymptotic closed form solution is proposed for the accurate representation of the tangential surface magnetic field within the paraxial region of a tangential magnetic current excited circular cylinder with an IBC. Similar to the treatment for the PEC case, Hankel functions are asymptotically approximated by a two-term Debye expansion within the spectral integral representation of the relevant Green's function pertaining to the IBC case. Although one of the two integrals within the spectral representation is evaluated in an exact fashion, the other integral for which an exact analytical evaluation does not appear to be possible is evaluated asymptotically, unlike the PEC case in which both integrals were evaluated analytically in an exact fashion. Validity of the proposed asymptotic solution is investigated by comparison with the exact eigenfunction solution for the surface magnetic field.     

Impact of zonal wind on latitudinal variation of total columnar ozone over the Indian Peninsula

Latitudinal and seasonal variability of total columnar ozone from September 2007 to August 2008 across the Indian longitude sector within 10.5° N to 34.5° N and 70.5° E to 94.5° E using satellite data obtained from Aura Ozone Monitoring Instrument (OMI) of National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) is presented. The total column ozone (TCO) over the area of study shows a gradually varying pattern throughout the year. In the post-monsoon (autumn) and winter months, maximum TCO is observed in the north-western part of the subcontinent while the minimum is often observed towards the east at about the same latitudes. A west–east spatial gradient is clearly observed in autumn months. As winter approaches, a north–south spatial gradient becomes more prominent than the east–west gradient. It has been further observed that TCO does not vary significantly over the entire subcontinent in monsoon.     

Antifungal activity and chemical composition of Citrus reticulata Blanco essential oil against phytopathogens from North East India

The essential oil (EO) isolated by hydro-distillation from the peel of fully matured ripen fruits of Citrus reticulata Blanco were analyzed by GC and GC-MS. Thirty seven different components were identified constituting approximately ≥99% of the oil. The major components were limonene (46.7%), geranial (19.0%), neral (14.5%), geranyl acetate (3.9%), geraniol (3.5%), β-caryophyllene (2.6%), nerol (2.3%), neryl acetate (1.1%) etc. The antifungal activity of the oil was tested by poisoned food (PF) technique and the volatile activity (VA) assay against five plant pathogenic fungi viz Alternaria alternata (Aa), Rhizoctonia solani (Rs), Curvularia lunata (Cl), Fusarium oxysporum (Fo) and Helminthosporium oryzae (Ho). The oil showed better activity in VA assay. The Minimum inhibitory concentration (MIC) for Aa, Rs and Cl was 0.2 ml/100 ml whereas >0.2 ml/100 ml for Fo and Ho in PF technique. Fungal sporulation was also completely inhibited at 2 ml/100 ml of the oil except for Cl and Ho, which was only 0.5% (±0.5) and 0.25% (±0.25) respectively as compared to control.     

An integrated path-planning and control approach for nonholonomic unicycles using switched local potentials

In this paper, navigation and control of an autonomous mobile unicycle robot in an obstacle-ridden environment is considered. The unicycle dynamic model used has two differentially driven wheels, with the motor torques as the system input. Two novel potential-field-based controllers are derived, which stabilize the robot within a surrounding circular area (henceforth called a bubble) of arbitrary size. The first controller takes the unicycle to the center of its bubble, while the second corrects its orientation. The designed potentials also work with a kinematic model. Explicit bounds for permissible initial speeds are derived, such that maximum torque limits and/or maximum speed limits are not violated once the controller is activated. These controllers are then embedded in a navigation framework. An existing global planner is used to first create a string of variable-sized bubbles which connect the start point to the goal point, with each bubble's size indicative of the radial obstacle clearance available from its center. The robot then keeps itself within a fixed-sized bubble, which it then moves in discrete steps, according to the direction provided by the global plan, while repulsively avoiding unexpected obstacles. Hence, the gross movement is created by switching local potential-field-based controllers. This scheme is first verified in computer simulation of a single robot moving in a maze. It is then implemented on an experimental setup of robots equipped with proximity sensors. Results are presented to illustrate the effectiveness of the system.