Effect of processing and microstructure on ultrasonic response of aerospace alloys: An overview

Ultrasonic testing is the primary nondestructive testing technique employed for examination of internal soundness in bulk materials. It also indicates materials condition and microstructure, and is influenced by these factors. Correlations among these shall help in establishing better understanding towards selection and application of materials for aerospace systems. This paper reviews the correlations between ultrasonic response and microstructure of different aerospace materials. It also includes the changes in ultrasonic response due to change in processing condition of material. It is noted that ultrasonic wave velocity and attenuation are modified by change in thermomechanical processing through change in microstructure.     

Silver nanoparticle/r-graphene oxide deposited mesoporous-manganese oxide nanocomposite for pollutant removal and supercapacitor applications

Mesoporous manganese oxide was prepared by a non-ionic surfactant route using Triton X-100, followed by Ag nanoparticle (NP) and graphene oxide incorporation by an ultra-sonication-assisted process. Fine Ag NPs were incorporated into the tubular texture of mesoporous manganese oxide. The crystalline phase, particle size, and morphology of the prepared materials were characterized by X-ray diffraction (XRD), Barrett–Joyner–Halenda–Brunauer–Emmett–Teller analysis, scanning electron microscopy–energy dispersive X-ray analysis, and high-resolution transmission electron microscopy (HR-TEM). The XRD results confirmed the formation of the Mn₂O₃ phase for the as-prepared mesoporous manganese oxide and its nanocomposite. Very fine Ag NPs (<5–10 nm) were obtained. The mesoporous MnO₂ and graphene-incorporated Ag NPs/meso-MnO₂ had a tubular structure and “flaky pastry”-type morphology for the synthesized nanocomposites. HR-TEM images further confirmed the beautiful structural formation upon graphene addition and spherical/dot-shaped NP incorporation into the matrix of MnO₂. Improved surface area was obtained for the Ag NPs and graphene-incorporated mesoporous MnO₂ as compared to bulk MnO₂. The Cr(VI) removal analysis was performed using a batch technique, and enhanced removal of Cr(VI) was achieved (>98% removal of Cr(VI) within 1–2 h of reaction time) for Ag NP-incorporated mesoporous MnO₂. Efficient activity was observed because of the fine Ag NPs present in mesoporous manganese oxide, as opposed to the case of graphene oxide-doped meso-MnO₂ and pristine mesoporous meso-MnO₂.     

An adaptive image sharpening scheme based on local intensity variations

Unsharp masking-based approaches are widely used in consumer electronics and printing technology for increasing the sharpness of the image. In the classical approaches, such improvements are achieved by adding the high-frequency details to the underlying image without considering any noise present in the image. As a result, such approaches yield visually poor results on noise-deteriorated images. In this paper, we propose an adaptive unsharp masking scheme which can tolerate the noise content, i.e., proposed algorithm will perform sharpening operation on the required regions thereby reducing the visual effects of the noise. Experimentally, it has been found out that the proposed approach yields better visual results than classical unsharp masking approach in the presence of noise.     

Solid self microemulsification of Atorvastatin using hydrophilic carriers: a design

Context: Atorvastatin has a limited advantage to formulate oral dosage forms.

Objective: To enhance the solubility of Atorvastatin and to design the suitable solid self-microemulsifying drug delivery systems (S-SMEDDS)

Materials and methods: The clear and transparent self-microemulsifying drug delivery system (SMEDDS) were formulated using coconut oil and isopropyl myristate as lipid phases; Tween 80 as surfactant; PEG 400 and glycerin as co-surfactant at 2:1, 3:1, 1:2 and 1:3 ratio. The pseudo ternary phase diagrams were constructed to identify the microemulsion region. The SMEDDS were evaluated for zeta potential, poly dispersity index, globule size, pH, viscosity and drug release. The solid SMEDDS were developed by employing adsorption and melt granulation methods. The S-SMEDDS were evaluated for micromeritics, morphology, solid state property, reconstitution ability, drug release and stability.

Results: The micro formulations formed with particle size of 25?nm had shown a 3-folds rise in drug release. The solid SMEDDS had reconstituted to a good microemulsion rapidly in 1–3?min, with a release of 94.62% at the end of 30?min and behaved as immediate releasing capsules. Their shelf-life was found to be 1.3 years.

Discussion: The 1:3 ratio SMEDDS had shown more drug release owing to their less particle size. The solid SMEDDS had shown an increased dissolution profiles than atorvastatin. The solid state of the drug had changed in formulation inferring their enhanced solubility.

Conclusion: The solid form of atorvastatin liquid SMEDDS had been formulated successfully with enhanced shelf life and solubility.     

Effect of waste activated sludge pretreatment methods to mitigate Gordonia foaming potential in anaerobic digestion

In this study, waste activated sludge obtained from two full‐scale treatment plants with foaming issues was pretreated with acid/alkali treatment, acid‐phase fermentation, thermal treatment, ultrasonic treatment and metal salt treatment to investigate their effect on foam mitigation. Waste activated sludge was characterized for foaming index prior and after each pretreatment method. Among all pretreatment methods investigated, acid/alkali treatment and acid phase fermentation showed highest reduction of 53% in foaming and in inactivation of Gordonia amarae filaments. Pretreatment methods that resulted in sharp decrease in the foaming index concurred with higher amounts of dead foam formers as confirmed using live/dead staining and the PMA‐qPCR technique. Pretreating with iron(III)chloride gave good foaming reductions with 54% decrease in foaming potential at a concentration of 260 mg/L but did not result in a decline of foam formers as confirmed by live/dead staining. Ultrasonic treatment did not prove effective in lowering the foaming index or killing the G. amarae filaments.     

Progress of Nanofluid Application in Machining: A Review

A colloidal mixture of nanometer-sized (<100 nm) metallic and non-metallic particles in conventional cutting fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. Therefore, nano-enhanced cutting fluids have recently attracted the attention of researchers. This paper presents a summary of some important published research works on the application of nanofluid in different machining processes: milling, drilling, grinding, and turning. Further, this review article not only discusses the influence of different types of nanofluids on machining performance in various machining processes but also unfolds other factors affecting machining performance. These other factors include nanoparticle size, its concentration in base fluid, lubrication mode (minimum quantity lubrication and flood), fluid spraying nozzle orientation, spray distance, and air pressure. From literature review, it has been found that in nanofluid machining, higher nanoparticle concentration yields better surface finish and more lubrication due to direct effect (rolling/sliding/filming) and surface enhancement effect (mending and polishing) of nanoparticles compared to dry machining and conventional cutting fluid machining. Furthermore, nanofluid also reduces the cutting force, power consumption, tool wear, nodal temperature, and friction coefficient. Authors have also identified the research gaps for further research.