Physicochemical studies of mild steel corrosion and atmospheric corrosivity mapping of Karachi: An important harbor city of modern Maritime Silk Route

This paper has reported physicochemical features of mild steel's corrosion products and provided atmospheric corrosivity maps of Karachi harbor city, drafted on the basis of spatial distribution of corrosion data from July 2018 to June 2019 at 10 different urban, industrial, and marine test sites. Exposure tests have been performed to study atmospheric corrosivity, corrosion products, and corrodants including chloride, sulfur dioxide, time of wetness (TOW), and corrosion rate as per ISO and ASTM standards. Scanning electron microscope, Fourier-transform infrared spectroscopy, and X-ray diffraction have corroborated the presence of lepidocrocite, goethite, magnetite, and quartz phases at almost all the test sites, with slight variations in their morphologies and quantities. The data analysis has revealed that TOW is a major detrimental factor to accelerate corrosion of mild steel at Karachi city. The corrosivity category of all urban and marine test sites is found in C₄–C₅ range, whereas for industrial test sites, it is found in C₃–C₅ range. Resultant corrosivity maps have shown that the prevailing atmosphere is significantly corrosive at Karachi harbor city. This study has furnished a novel product of atmospheric corrosivity map, which is the first-ever corrosivity map for Pakistan.     

Durable and Recyclable Superhydrophobic Fabric and Mesh for Oil–Water Separation

The authors report durable and recyclable nanocomposite superhydrophobic coatings on two different substrates of fabric and mesh as prepared by titania nanoparticles and polydimethysiloxane (PDMS). The felted wool fabric and the steel mesh are initially coated with a thin layer of PDMS, which is followed by the deposition of nanocomposite coating of titania nanoparticles embedded in PDMS. The dual surface modification of two kinds of substrates generates highly hydrophobic surface character, which is retained after durability performance as measured in ultrasonication, sand, and emery paper abrasion tests. Oil–water separation experiments are performed using water mixtures with four oils, that is, n‐hexane, toluene, kerosene, and diesel to ensure the industrial applications of prepared composite materials. Moreover, nanocomposite coatings are tested for several cycles of oil–water separation in harsh conditions such as hot water, sodium chloride, and hydrochloric acid. The adopted approach improves the separation performance by inducing durability of the prepared nanocomposite coatings along with introducing recyclable character.     

Interdependence of piezoelectric coefficient and film thickness in LiTaO3 cantilevers

Electromechanical energy demands on homogenous thick films of piezoceramics with sufficiently large piezoelectric constant and reproducible performance. Single-phase LiTaO₃ films deposited by sol-gel processing have been fabricated as cantilevers to investigate the interdependence of dielectric and piezoelectric properties as a function of film thickness. Phase pure LiTaO₃ films with varying thickness in the range of 2.07-4.37 µm on stainless steel substrates were obtained after calcination of samples at 650°C. The relative permittivity of optimized spin-coated films peaked at 479.73 (1 kHz), whereas the piezoelectric coefficient (d₃₃ mode) determined by piezoresponse force microscopy was in the range of 21-24 pm/V. The effect of poling was studied through the butterfly and phase curves. A figure of merit (FOM) up to 3.29 (10⁻¹⁸ m²/V²) was determined for cantilever devices, which were able to generate a peak-to-peak voltage of 0.046-0.15 V using a 1 MΩ resistor as an impedance load at a fixed acceleration of 1.5 m/s². While the power density was in the range of ~4-20 × 10⁻⁹ W/m³, which increased with the increasing film thickness. The leakage current density decreased in the range of 4 × 10⁻⁵-6 × 10⁻⁷ A/m² in the same direction. As both ferroelectric and piezoelectric properties of LiTaO₃ films are dependent on film thickness, an optimal energy conversion efficiency was obtained for a thickness of ~3 µm. Furthermore, these devices were tested up to a temperature of 150°C for voltage generation. Given the need for lead-free piezoelectric materials for environmental applications, these LiTaO₃ cantilevers are very promising for vibrational energy harvester (VEH) applications especially due to their cost effectiveness, small size, stability at higher temperatures, and repeatable properties, which makes them suitable for MEMS devices for industrial applications.     

Capillary driven flow in wettability altered microchannel

The capillary driven flow of water inside a microchannel with altered wettabilities is experimentally investigated and modeled theoretically. The surfaces of the PDMS made microchannel are exposed to oxygen plasma, rendering the surfaces increasingly hydrophilic, which provides the driving force for the flow. The plasma treated surfaces are characterized using topography and phase imaging of AFM scanning, as well as nano‐indentation, to correlate the distinct structural changes to the hydrodynamic profiles of the advancing meniscus. The experimental results are further analyzed using a newly proposed slip velocity model. The aim is to obtain a qualitative relationship between the surface properties and the flow parameters, namely the advancing meniscus velocity and pressure drop inside the channel. The insights are of fundamental importance in diverse fields, such as enhanced oil recovery, microfluidic devices, cell separation, and pathology. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4616–4627, 2017     

The effects of thermomechanical processing on the precipitation in an industrial dual-phase steel microalloyed with titanium

Analytical transmission electron microscopy was employed to characterize the precipitation at each step of the fabrication process and thermomechanical treatment of an industrial dual-phase steel microalloyed with titanium. Theoretical thermodynamic calculations as well as experimental analysis showed that more than half of the titanium carbosulfide (Ti₄C₂S₂) precipitates would dissolve during reheating at 1240 °C. Despite this dissolution at 1240 °C, the remaining titanium carbonitrides and carbosulfides were effective in pinning austenitic grain boundaries, keeping the austenitic grain size at around 40 μm (at 1240 °C). It is also shown that, during hot rolling, there exist three regions of titanium carbide precipitation. The first is defined by an increase of titanium carbide precipitation due to deformation. The second region is marked by the insignificant change in precipitation. The third region is indicated by another increase in precipitation due to the austenite-to-ferrite transformation. The experimental and theoretical results on the contribution of TiC precipitation to hardening of ferrite (Orowan mechanism) were in excellent agreement, showing that TiC precipitates have the most important effect on increasing the yield strength, overshadowing the austenitic grain-boundary pinning contributions by Ti(C,N) and Ti₄C₂S₂ precipitates.     

Nutritive value of canola (Brassica napus L.) as affected by plant growth promoting rhizobacteria

Comparative evaluation of plant growth promoting rhizobacteria viz. Azospirillum brasilense, Azotobacter vinelandii Khsr1 and chemical fertilizers was made on growth, protein, and oil yield as well as quality of canola (Brassica napus L.) cv. Rainbow. The A. brasilense and A. vinelandii were applied as seed inoculation at 10⁶ cells/mL. The recommended doses of urea (150 kg/ha) and diamonium phosphate (180 kg/ha) were applied as sources of chemical fertilizers. First dose of chemical fertilizers was applied at the time of sowing while other three doses were applied at 45 days interval. The chemical fertilizers were highly effective in increasing leaf chlorophyll content, number of branches per plant, number of siliqua per branch, number of seeds per siliqua, and total seed yield. A. brasilense treatment increased the leaf and seed protein content (32 and 21%) as well as seed size as measured by % increase in 1000 seed weight. A. vinelandii treatment resulted in significant increase (4%) in seed oil contents but the glucosinolate and erucic acid (C22:1) contents of oil was decreased significantly. Maximum oleic acid (C18:1) content was found in seed oil of A. vinelandii treatment; whereas, significantly higher linolenic acid (C18:3) content was recorded in A. brasilense treatment. It is inferred from the present investigation that A. brasilense and A. vinelandii could be highly effective in improving yield and nutritive value of canola oil.     

Development of thiolated poly(acrylic acid) microparticles for the nasal administration of exenatide

The purpose of this study was to develop a microparticulate formulation for nasal delivery of exenatide utilizing a thiolated polymer. Poly(acrylic acid)-cysteine (PAA-cys) and unmodified PAA microparticles loaded with exenatide were prepared via coprecipitation of the drug and the polymer followed by micronization. Particle size, drug load and release of incorporated exenatide were evaluated. Permeation enhancing properties of the formulations were investigated on excised porcine respiratory mucosa. The viability of the mucosa was investigated by histological studies. Furthermore, ciliary beat frequency (CBF) studies were performed. Microparticles displayed a mean size of 70–80?µm. Drug encapsulation was ～80% for both thiolated and non-thiolated microparticles. Exenatide was released from both thiolated and non-thiolated particles in comparison to exenatide in buffer only within 40?min. As compared to exenatide dissolved in buffer only, non-thiolated and thiolated microparticles resulted in a 2.6- and 4.7-fold uptake, respectively. Histological studies performed before and after permeation studies showed that the mucosa is not damaged during permeation studies. CBF studies showed that the formulations were cilio-friendly. Based on these results, poly(acrylic acid)-cysteine-based microparticles seem to be a promising approach starting point for the nasal delivery of exenatide.     

Pulmonary vagal innervation is required to establish adequate alveolar ventilation in the newborn lamb

alpha5-deficient mice die early in embryogenesis (). To study the functions of alpha5 integrin later in mouse embryogenesis and during adult life we generated alpha5 -/-;+/+ chimeric mice. These animals contain alpha5-negative and positive cells randomly distributed. Analysis of the chimerism by glucose- 6-phosphate isomerase (GPI) assay revealed that alpha5 -/- cells contributed to all the tissues analyzed. High contributions were observed in the skeletal muscle. The perinatal survival of the mutant chimeras was lower than for the controls, however the subsequent life span of the survivors was only slightly reduced compared with controls (). Histological analysis of alpha5 -/-;+/+ mice from late embryogenesis to adult life revealed an alteration in the skeletal muscle structure resembling a typical muscle dystrophy. Giant fibers, increased numbers of nuclei per fiber with altered position and size, vacuoli and signs of muscle degeneration-regeneration were observed in head, thorax and limb muscles. Electron microscopy showed an increase in the number of mitochondria in some muscle fibers of the mutant mice. Increased apoptosis and immunoreactivity for tenascin-C were observed in mutant muscle fibers. All the alterations were already visible at late stages of embryogenesis. The number of altered muscle fibers varied in different animals and muscles and was often increased in high percentage chimeric animals. Differentiation of alpha5 -/- ES cells or myoblasts showed that in vitro differentiation into myotubes was achieved normally. However proper adhesion and survival of myoblasts on fibronectin was impaired. Our data suggest that a novel form of muscle dystrophy in mice is alpha5-integrin-dependent.     

Disorder Induced Magnetic Behavior of Non-Stoichiometric Co0.75Mn0.5Fe0.75Si Full-Heusler Alloy

Journal of Superconductivity and Novel Magnetism - Many stoichiometric Heusler alloys have been extensively investigated in recent years due to their wide range of magnetic properties. However, a...