Role of alkaline nitrites in the corrosion performance of steel in composite cements

The influence of alkaline nitrites on the inhibition of corrosion of steel in binary and ternary cement environments was tested. pH measurements carried out for binary and ternary cement extracts showed that the alkalinity of the cement was not affected by making use of binary and ternary cements. Gravimetric measurements showed that the decrease in the corrosion rate of steel in different systems follows the order: Ternary > (OPC + PSC) > (OPC + PPC) > (PPC + PSC). Potential–time studies indicated that the ability to maintain the passivity of steel in different systems also follows the order as above. Potentiodynamic polarisation studies for steel in binary and ternary cement environments showed the favourable influence of the presence of higher amounts of chlorides. Nitrites of sodium, potassium and calcium act as anodic inhibitors and they compete with chloride ions for the ferrous ions at the steel to form a film of ferric oxide. An efficiency as high as 91% is obtained for the ternary system containing 1% chloride and 0.5% nitrite. The degree of surface coverage showed a maximum value for the ternary system (>0.9) even in the presence of a higher amount of chloride thereby indicating the better performance of the system.     

Studies on phase formation,microstructure development and elastic properties of reduced NiO–8YSZ anode supported bi-layer half-cell structures of solid oxide fuel cells

Half-cell structures of solid oxide fuel cells (SOFCs) with a thin and dense electrolyte layer of 8YSZ supported by a thick and porous NiO–8YSZ anode precursor structure were reduced in a gas mixture of 5% H₂–95% Ar at 800 °C for selected time periods in order to fabricate cermets with desired microstructure and composition, and to study their effects on the elastic properties at ambient and reactive atmospheres. It appears that 2 h of exposure to the reducing conditions is enough to reduce ～80% of NiO with an enhanced porosity value of 35%. The Ni–8YSZ cermet phase formation in the anode was analyzed with X-ray diffraction (XRD) in correlation with its microstructure. The elastic properties were determined after the reduction, at room and elevated temperatures using the impulse excitation technique. At room temperature the decrease in the Young's modulus was about 44% (after 8 h of reduction) and can be attributed mainly to the changes in the microstructure, particularly the increase in porosity from ～12% to 37%. Young's moduli of the as-received precursor and reduced anodes were evaluated as a function of temperature in air and reducing atmosphere. The results were explained in correlation to the initial porosity, composition and oxidation of Ni at the elevated temperatures.     

High-Performing Atomic Electrocatalyst for Chlorine Evolution Reaction

Electrocatalysts facilitating chlorine evolution reaction (ClER) play a vital role in chlor–alkali industries. Owing to a huge amount of chlorine consumed worldwide, inexpensive high-performing catalysts for Cl₂ production are highly demanded. Here, a superb ClER catalyst fabricated through uniform dispersion of Pt single atoms (SAs) in  C₂N₂ moieties of N-doped graphene (denoted as Pt-1) is presented, which demonstrates near 100% exclusive ClER selectivity, long-term durability, extraordinary Cl₂ production rate (3500 mmol h⁻¹ g_Pt⁻¹), and >140 000-fold increased mass activity over industrial electrodes in acidic medium. Excitingly, at the typical chlor–alkali industries’ operating temperature (80 °C), Pt-1 supported on carbon paper electrode requires a near thermoneutral ultralow overpotential of 5 mV at 1 mA cm⁻² current density to initiate the ClER, consistent with the predicted density functional theory (DFT) calculations. Altogether these results show the promising electrocatalyst of Pt-1 toward ClER.     

Green synthesised iron and iron‐based nanoparticle in environmental and biomedical application: – a review

Owing to the development of nanotechnology and its influence in various fields, the development of efficient and environmental friendly technique for the synthesis of nanomaterials is important. Among the various traditional and conventional methods available for the synthesis, plant‐mediated synthesis seems to be a very attractive and environmental friendly method, attributing to its simple methodology and eco‐friendly approach. The synthesis rate and stability of the nanoparticle synthesised are good when compared to the other methods of synthesis and it is proved to be efficient in various fields of application. Hence, the present review article deals with furnishing information about the plant sources used so far and details about the environmental and biomedical applications of the synthesised nanoparticles.Inspec keywords: nanoparticles, reviews, nanomedicine, nanofabrication, antibacterial activity, ironOther keywords: environmental application, biomedical application, iron‐based nanoparticle, environmental friendly technique, traditional methods, plant‐mediated synthesis, environmental friendly method, simple methodology, eco‐friendly approach, synthesis rate, nanoparticle stability, green synthesis, nanotechnology, nanomaterials, conventional methods, Fe     

Dimensionality reduction based on rough set theory: A review

A rough set theory is a new mathematical tool to deal with uncertainty and vagueness of decision system and it has been applied successfully in all the fields. It is used to identify the reduct set of the set of all attributes of the decision system. The reduct set is used as preprocessing technique for classification of the decision system in order to bring out the potential patterns or association rules or knowledge through data mining techniques. Several researchers have contributed variety of algorithms for computing the reduct sets by considering different cases like inconsistency, missing attribute values and multiple decision attributes of the decision system. This paper focuses on the review of the techniques for dimensionality reduction under rough set theory environment. Further, the rough sets hybridization with fuzzy sets, neural network and metaheuristic algorithms have also been reviewed. The performance analysis of the algorithms has been discussed in connection with the classification.     

Parallel algorithms for generating combinatorial objects on linear processor arrays with reconfigurable bus systems

A bus system whose configuration can be dynamically changed is called reconfigurable bus system. In this paper, parallel algorithms for generating combinations, subsets, and binary trees on linear processor array with reconfigurable bus systems (PARBS) are presented. Preliminary version of this paper has been presented at the 6th National Seminar on Theoretical Computer Science, held at Bhanasthali Vidyapith, Aug. 8–12, 1996     

Immunomodulating capacity of kefir

Kefir is a fermented milk produced by the action of lactic acid bacteria, yeasts and acetic acid bacteria, trapped in a complex matrix of polysaccharides and proteins. Beyond its inherent high nutritional value as a source of proteins and calcium, kefir has a long tradition of being regarded as good for health in countries where it is a staple in the diet. However, published human or animal feeding trials to substantiate this view are not numerous. The aim of this work was to determine the immunomodulating capacity of kefir on the intestinal mucosal immune response in mice and to demonstrate the importance of dose and cell viability on this response. BALB/c mice were fed with commercial kefir ad libitum (diluted 1/10, 1/50, 1/100 or 1/200) or pasteurized kefir (diluted 1/6, 1/10, 1/50, 1/100) for 2, 5 or 7 consecutive days. At the end of each feeding period, the bacterial translocation assay was performed in the liver. Small intestine structure was studied by haematoxilin-eosin staining and light microscopy. The number of IgA+ and IgG+ cells was also determined. For the functional doses chosen, cytokines (IL-2, IL-4, IL-6, IL-10, IL-12, TNF-alpha and IFN-gamma) were determined. Kefir and pasteurized kefir were able to modulate the mucosal immune system in a dose-dependent manner. Kefir was administred 10-times more diluted than pasteurized kefir, but it induced an immunomodulation of similar magnitude, indicating the importance of cell viabilty. The results suggest that a Th1 response was controlled by Th2 cytokines induced by kefir feeding. Pasteurized kefir would induce both Th2 and Th1 responses. This is the first study in vivo regarding the mechanisms involved in the immunomodulating capacity of the oral administration of kefir containing viable or heat-inactivated bacteria at different doses.     

A comparative study of the kinetic theories of the glass transition phenomenon in high polymers

The effect of thermal history on the glass transition temperature (T_g) of poly(vinyl chloride) was studied. The parameters like the hole energy (E_h), the activation energy for the disappearance of holes (E_j), the activation enthalpy for the structural relaxation (Δh1* and Δh2*) and the activation energy for the glass transition process (E) were calculated. The increase of E_h value with the increase in T_g value shows that there exists a holesize distribution. The E_j (26.9 ± 0.5 kcal/mol) value calculated according to Wunderlich's treatment, the Δh1* (27.8 ± 0.6 kcal/mol) value obtained by Moynihan's procedure and the E (35.3 kcal/mol) value from Barton-Critchley's method agree well with one another in the poly(vinyl chloride) system. The Δh2* quantity, obtained through Moynihan's formulations, increase as the rate of heating was increased, a result similar to the variation of E_h value with the rate of heating.     

Hydrothermal Growth of Undoped and Zn-Doped SnO Nanocrystals: A Frequency Dependence of AC Conductivity and Dielectric Response Studies

Semiconductors - The aim of this work is to investigate the dielectric properties of undoped and Zn-doped Tin monoxide (SnO) nanocrystals synthesized by the hydrothermal technique. The prepared...     

A study on utilization of ground source energy for space heating using a nanofluid as a heat carrier

Ground source heat pump (GSHP) systems are well established as an energy-efficient space conditioning device. However, for better utilization of the ground source, improvement in GSHP performance is desirable, which limits the small temperature difference between the ground and the circulating fluid. In this study, efforts have been made to investigate the performance of a ground heat exchanger (GHX) with a nanofluid as a heat carrier. Mathematical modeling is performed for the closed-loop vertical U-tube GHX with six different (Al₂O₃, CuO, graphite, multiwalled carbon nanotube, graphene, and Cu) water-based nanofluids. The effect of different operating parameters on GHX length, fluid temperature, and pressure drop with nanofluids is determined. On the basis of the analytical results, it is found that the graphite particle-based nanofluid plays a prominent role to enhance the performance of the GHX as compared with other nanoparticles. The maximum enhancement in the increase in outlet fluid temperature and reduction in pipe length with graphite particle-based nanofluid are 68.3% and 63.3%, respectively, for an increase in temperature difference from 7°C to 15°C between the atmosphere and the ground. Also, with the graphite particle-based nanofluid and the increase in pipe diameter from 20 to 50 mm, the fluid outlet temperature increases up to 11.2%, and the requirement in GHX length reduces up to 55%.