Bioinspired Heterocyclic Compounds as Corrosion Inhibitors: A Comprehensive Review

Corrosion is a phenomenon that devastatingly affects innovative, industrial, and mechanical applications, especially in the oil and gas industries. The corrosion conceivably influences industrial equipment; it deteriorates the environment and lessens the equipment/infrastructure's lifetime. Considering the significant impact of corrosion in our daily lives, this review article aims to briefly discuss the significance of corrosion and different control methods with special attention on corrosion inhibitors. The classification of corrosion inhibitors based on types and their advantage/limitations, and heterocyclic compounds as potential corrosion inhibitors, mainly nitrogen-based compounds (pyridine (1N), pyrimidine (2N), and triazines (3N) fused ring benzimidazole, etc.), and their biological significance has been discussed in detail. The mechanism, challenges, and applications of heterocyclic compounds as corrosion inhibitors in various industrial relevant corrosive environments such as acid pickling, descaling operation in the desalination plant, oil gas industry, etc., have also been highlighted in the review.     

Morphology of carbon nanotubes prepared via chemical vapour deposition technique using acetylene: A small angle neutron scattering investigation

Small angle neutron scattering (SANS) has been utilized to study the morphology of the multi-walled carbon nanotubes prepared by chemical vapour deposition of acetylene. The effects of various synthesis parameters like temperature, catalyst concentration and catalyst support on the size distribution of the nanotubes are investigated. Distribution of nanotube radii in two length scales has been observed. The number density of the smaller diameter tubes was found more in number compared to the bigger one for all the cases studied. No prominent scaling of the structure factor was observed for the different synthesis conditions.      

A Review on Mechanistic Insight of Plant Derived Anticancer Bioactive Phytocompounds and Their Structure Activity Relationship

Cancer is a disorder that rigorously affects the human population worldwide. There is a steady demand for new remedies to both treat and prevent this life-threatening sickness due to toxicities, drug resistance and therapeutic failures in current conventional therapies. Researchers around the world are drawing their attention towards compounds of natural origin. For decades, human beings have been using the flora of the world as a source of cancer chemotherapeutic agents. Currently, clinically approved anticancer compounds are vincristine, vinblastine, taxanes, and podophyllotoxin, all of which come from natural sources. With the triumph of these compounds that have been developed into staple drug products for most cancer therapies, new technologies are now appearing to search for novel biomolecules with anticancer activities. Ellipticine, camptothecin, combretastatin, curcumin, homoharringtonine and others are plant derived bioactive phytocompounds with potential anticancer properties. Researchers have improved the field further through the use of advanced analytical chemistry and computational tools of analysis. The investigation of new strategies for administration such as nanotechnology may enable the development of the phytocompounds as drug products. These technologies have enhanced the anticancer potential of plant-derived drugs with the aim of site-directed drug delivery, enhanced bioavailability, and reduced toxicity. This review discusses mechanistic insights into anticancer compounds of natural origins and their structural activity relationships that make them targets for anticancer treatments.     

Mechanism of pre-annealing effect on electromigration immunity of Al–Cu line

In this work, we have investigated effects of pre-annealing, which means annealing performed prior to electromigration (EM) test, on EM lifetime of Al–Cu lines. We also investigated the relationships between void formation and size of Cu precipitated area in the line under various pre-annealing conditions. It is found that EM lifetime decreases while the size of the Cu precipitated area increases with lengthening of the pre-annealing period. However, no void is observed after this pre-annealing treatment. The results indicate that the tiny voids generated by formation of Cu precipitation do not move during the pre-annealing period. In the case of EM testing, Cu precipitation occurs followed by void formation at the cathode area, probably due to diffusion of vacancies which are generated by Cu atom movement by electron wind. As a result, resistance of the line increases and eventually it fails completely.It is demonstrated that pre-annealing helps Cu atoms to accumulate at the grain boundary forming the Cu precipitates. However, in samples with no pre-annealing treatment, the accumulation of Cu atoms at the grain boundaries begins just after the start of the EM testing and then the Cu precipitates diffuse toward the anode. Since EM test conditions are the same for samples with and without pre-annealing treatment, the only variation is the incubation time to accumulate Cu atoms at the grain boundaries. This is the reason why EM lifetime of pre-annealed samples is shorter than that of samples with no pre-annealing treatment.     

Al319激光表面合金化

用激光表面合金化的方法加入Ni、Cr等成分在铝合金基体材料表面形成具有良好耐磨性能的合金化层。实验首先将合金粉末调和后涂于试样表面,用CO_2激光以不同功率、不同的光斑移动速度对徐层进行激光合金化处理。分析结果表明,工艺参数极大地影响合金化效果;可得到显微硬度达1400HV的高度硬化层;选用合适的功率、光斑运动速度及预涂层厚度可得到单道轨迹、多道搭接及整个试样表面的无气孔、裂纹缺陷的组织细密的合金化层;层内主要强化相为AlNi和多种Al/Ni金属间化合物。最终得到的全试样表面合金化层的硬度比基体高60—100HV,耐磨性比基材提高3—5倍。     

Parallel testing of parametric faults in a three-dimensionaldynamic random-access memory

A testable design of dynamic random-access memory (DRAM) architecture which allows one to access multiple cells in a word line simultaneously is presented. The technique utilizes the two-dimensional (2-D) organization of the DRAM and the resulting speedup of the conventional algorithm is considerable. The failure mechanism in the three-dimensional (3-D) DRAM with trench-type capacitor is specifically investigated. As opposed to the earlier approaches for testing parametric faults that used sliding diagonal-type tests with O(n^3/2) complexity, the algorithms discussed here are different and have O(√n/p) complexity, where p is the number of subarrays within the DRAM chip. These algorithms can be applied externally from the chip and also they can be easily generated for built-in self-test applications     

Effects of N distribution on charge trapping and TDDBcharacteristics of N2O annealed wet oxide

Wet pyrogenic oxide of different thicknesses was annealed in N₂O ambient and the N concentration in the films was studied by using SIMS (secondary ion mass spectroscopy). It was found that for a certain annealing time and temperature, the N concentration (at %) increases with decreasing wet oxide thickness and the location of the peak of N is observed near the interface of nitrided oxide and Si substrate. On the contrary, after nitridation the concentration of H is higher in the thicker wet oxide of thickness 100 Å and also does not change much from the surface to the interface. For the thinner wet oxide of thickness 40 Å, the concentration of H is less and decreases toward the interface. Gate dielectrics were characterized using high-frequency and quasi-static measurements. After a constant current stress, a large distortion was observed for the N₂O annealed wet oxide of 98 Å whereas for the N₂O annealed wet oxide of 51 Å the distortion was small. With increasing stressing time, hole trap is followed by electron trapping for the wet oxide of 98 Å whereas for the N₂O annealed wet oxide of 51 Å, hole trapping increases a little at the beginning and then saturates. From the TDDB characteristics, a longer t_BD was observed for N₂O annealed wet oxide of 51 Å compared to 98 Å. From the experimental results, it can be suggested that the improved reliability of thin gate oxide is due to the large amount of N concentration near the interface only. Hence for the device fabrication process, if the wet oxide is nitrided in N₂O ambient, the reliability of gate oxide will be improved in the ultrathin region     

New March Tests for Multiport RAM Devices

This paper describes three new march tests for multiport memories. A read (or write) port in such a memory consists of an n-bit address register, an n-to-2ⁿ-bit decoder (with column multiplexers for the column addresses) and drivers, and a K-bit data register. This approach gives comprehensive fault coverage for both array and multiport decoder coupling faults. It lends itself to a useful BIST implementation with a modest area overhead that tests these faults and achieves low test application time.     

Competitive Methane Desorption by Supercritical CO2 Injection in Coal

A large diameter (∼70 mm) dry coal sample was used to study the competitive displacement of CH₄ by injection of supercritical CO₂, and CO₂–CH₄ counter-diffusion in coal matrix. During the test, a staged loading procedure, which allows the calibration of the key reservoir modelling parameters in a sequential and progressive manner, was employed. The core-flooding test was history matched using an Enhanced Coalbed Methane (ECBM) simulator, in which Fick’s Law for mixed gas diffusion and the extended Langmuir equations are implemented. The system pressure rise during the two loading stages and the CO₂ breakthrough time in the final production stage were matched by using the pair of constant sorption times (9 and 3.2 days) for CH₄ and CO₂, respectively. The corresponding diffusion coefficients for CH₄ and CO₂ were estimated to be 1.6 ×  10⁻¹² and 4.6 ×  10⁻¹² m²/s, respectively. Comparison was made with published gas diffusion coefficients for dry ground samples (ranging from < 0.063 to ∼3 mm) of the same coal at relatively low pressures (< 4 MPa). The CO₂/CH₄ gas diffusion coefficient ratio was well within the reported range (2–3), whereas the CH₄ diffusion coefficient obtained from history matching of the core-flooding test is approximately 15 times smaller than that arrived by curve-fitting the measured sorption uptake rate using a unipore diffusion model. The calibrated model prediction of the effluent gas composition was in good agreement with the test data for CO₂ mole fraction of up to 20%.     

Dispersion of reactive species with reversible and irreversible wall reactions

The longitudinal dispersion of a chemical species released in an oscillatory flow through an annular tube has been studied in presence of two kinds of first order reactions between the species and tube-wall. The species is supposed to undergo kinetic reversible phase exchange with the outer-wall material and irreversible absorption into the wall. Due to the variation of velocity across the tube section, the chemical species may spread out axially along the tube at a much faster rate than that produced by the molecular diffusion. A finite-difference implicit scheme has been adopted to solve the unsteady convection-diffusion equation for all time period based on the Aris method of moments. Axial distributions of mean concentration are determined from the first four central moments using Hermite polynomial representation for the periodic flow with and without non-zero mean flow. The study brings forward the coupled effects of reversible phase exchange and irreversible absorption on dispersion coefficient. Both the reversible and irreversible reactions are found to inhabit the dispersion process at early times, but at developed stage dispersion may be enhanced by the reversible phase exchange, provided the velocity comprises time invariant component. The decrease of peak of the mean concentration distribution with the increase of reaction rate is found irrespective of the nature of reaction.