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This paper aims to study the various developments taking place in the field of gas sensors made from polyaniline (PANI) nanocomposites, which leads to the development of high-performance electrical and gas sensing materials operating at room temperature.

PANI/ferrite nanocomposites exhibit good electrical properties with lower dielectric losses. There are numerous reports on PANI and ferrite nanomaterial-based gas sensors which have good sensing response, feasible to operate at room temperature, requires less power and cost-effective.

This paper provides an overview of electrical and gas sensing properties of PANI/ferrite nanocomposites having improved selectivity, long-term stability and other sensing performance of sensors at room temperature.

The main purpose of this review paper is to focus on PANI/ferrite nanocomposite-based gas sensors operating at room temperature.

The purpose of this paper is to study the effect of heat treatment (HT) applied to an API X60 steel in corrosion resistance and stress corrosion cracking (SCC) susceptibility through slow strain rate tests (SSRT) in NS4 solution and congenital water (CW) to assess external and internal SCC, respectively.

API X60 steel was heat treated at a temperature of 1,200°C for 30 min followed by water quenching. Specimens from this steel were machined according to NACE TM 198. SSRT were performed in a constant extension rate tests (CERT) machine at room temperature at a strain rate of 1 × 10^–6 s^–1. For this purpose, a glass cell was used. Corrosion behavior was evaluated through polarization curves (PCs).

The SCC index obtained from SSRT indicates that the steel heat treated could be susceptible to SCC in CW and NS4 solution; the mechanism of SCC was hydrogen embrittlement. Thus, CW may promote the SCC phenomenon in pipelines. HT improves the steel corrosion resistance. Higher corrosion rate (CR) was observed when the steel is exposed to CW. The corrosion process in X60 steel shows that the oxidation reaction in the anodic branch corresponds to an activation process, and the cathode branches reveal a diffusion process.

The purpose of the heat treatment applied to X60 steel was to generate a microstructure of acicular ferrite to improve the corrosion resistance and SCC behavior.

This paper aims to study the structural, electrical and microwave properties of (Sr_0.6Ca_0.4) (Co_yMn_1−y) O₃ (0.2 ≤ y ≤ 1.0) thick-film ceramics.

The thick films of (Sr_0.6Ca_0.4) (Co_yMn_1−y) O₃ (0.2 ≤ y ≤ 1.0) on the alumina substrate have been delineated using screen printing technique. The structural analysis was carried out using an X-ray diffraction method and scanning electron microscopy. The direct current (DC) electrical resistivity is measured using a two-probe method. Microwave absorption was studied in the 8-18 GHz frequency range by using the Waveguide Reflectometer Method. The permittivity and permeability in the 8-18 GHz frequency range were measured by using Voltage Standing Wave Ratio slotted section method.

The thick films have orthorhombic perovskite structure with dominant (020) plane. By using first-principle calculation method, theoretical and experimental lattice parameter and cell volume of (Sr_0.6Ca_0.4) (Co_yMn_1−y) O₃ are matched with each other. The cobalt content changes the morphology from plates to needles. The DC electrical resistivity increases with increase in Co content and decreases with increase in temperature. (Sr_0.6Ca_0.4) (Co_yMn_1−y) O₃ thick film shows 75 per cent microwave absorption both in the X band and Ku band. The microwave permittivity and permeability decreases with increase in frequency and Co content.

Structural, electrical and microwave properties of (Sr_0.6Ca_0.4) (Co_yMn_1−y) O₃ (0.2 ≤ y ≤ 1.0). Thick film ceramics on alumina substrate is reported for the first time.

The purpose of this study is to evaluate the content of bioactive pigments in coloured callus of Azadirachta indica and to understand the correlation between the callus colours with their bioactive constituents, antioxidant properties and cytotoxicity. These assessments will yield valuable insight into the use of in vitro-derived pigments for possible use as functional natural colourants.

In this study, the authors have successfully developed a protocol to produce leaf-derived callus of various colours with enhanced content of bioactive pigments in A. indica through plant tissue culture. Comparative analysis of the pigments content (chlorophyll, carotenoid, phenolics and anthocyanins) in the coloured callus was conducted, followed by evaluation of its bioactive properties. The antioxidant properties against 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, ferric reducing antioxidant power and cytotox activities of the coloured callus extracts were also reported.

Callus of various colours were successfully produced in A. indica through plant tissue culture, and their valuable pigment content and bioactivity were evaluated. The green callus contained the highest amount of anthocyanin, followed by brown and cream callus. The total anthocyanin contents in both the green and brown callus was more than two-fold higher than that in cream callus. Contrasting observation was obtained for total phenolic content (TPC), where the TPC of cream callus was significantly higher than that in brown callus. Nevertheless, the green callus also exhibited the highest TPC. Green callus also contained the highest amount of total chlorophyll and carotenoid, as well as exhibited the highest antioxidant potential, and was found to be the only extract with active cytotox activity against SKOV-3 cells. Correlation analysis revealed that the excellent bioactivity exhibited by the coloured extracts was strongly correlated with the bioactive pigments present in the callus.

The major bioactive compounds identified in the methanolic extracts of A. indica coloured callus are anthocyanins, phenolics, chlorophylls and carotenoids. Future research work should include improvements in the extraction and identification methods, which may lead to detection and determination of other compounds that could attribute to its bioactivity, to complement the findings of the current study.

This analysis provides valuable information on the application of plant tissue culture as an alternative source for sustainable production of major pigments with medicinal benefits in A. indica for possible use as functional natural colourants.

A comparative study on bioactive pigment production in coloured callus from A. indica leaves and its antioxidant potential and cytotoxicity is original. To the best of the authors’ knowledge, this is the first report detailing a comparative evaluation on the production of coloured callus in A. indica and its relative biochemical composition and bioactive properties.

This paper aims to use an imidazole-based n-ionic Gemini surfactant derived from palm oil to inhibit the sulfide stress corrosion cracking of a supermartensitic stainless steel.

The slow strain rate testing technique, hydrogen permeation tests and potentiodynamic polarization curves have been used.

Addition of the inhibitor below the critical micelle concentration (CMC) decreased the corrosion current density (i_corr), but not enough to avoid embrittlement due to the entry of hydrogen into the steel. Instead, the addition of the inhibitor close to the CMC decreased the i_corr, suppressed the entry of hydrogen and inhibited the sulfide stress cracking of steel. Finally, the addition of inhibitor above the CMC led to a slight increase of i_corr and promoted localized corrosion, however, the sulfide stress cracking of steel was inhibited.

A green sulfide stress corrosion cracking inhibitor of a supermartensitic stainless steel has been obtained.

This paper aims to fabricate a FeS/Cu-Bi copper-based lead-free bearing material to maintain good friction-reducing and anti-adhesive properties under boundary lubrication conditions.

The materials were fabricated by mechanical alloying and powder metallurgy and tested under dry friction conditions using HDM-20 wear tester.

The results show that mechanical alloying can improve the antifriction and wear resistance of the materials. The 6 per cent FeS and 6 per cent Bi in the copper-based bearing materials fabricated by mechanical alloying have a better synergism which contributes to the friction and wear properties of copper matrix.

This new approach solves the problems of Bi and FeS mutual segmentation, mutual agglomeration and poor interface bonding.

The purpose of this paper is to study the effect of the material inhomogeneity on crack behavior initiated both axially and circumferentially in or near the butt weld and to discuss consequences on residual lifetime of the welded structure.

A three‐dimensional numerical model of pipe weld with smooth and continuous change of material properties has been used to study the fracture behavior of the cracked pipe structure. The stress intensity factor was considered as a parameter controlling the fracture behavior. The semi‐elliptical shape of the crack front was estimated under assumption of constant stress intensity factor along the crack front.

According to the results obtained in the paper the following conclusions were deduced. First, the most critical location of the crack is in the middle of the inhomogeneous region (weld center) regardless of the crack orientation. The stress intensity factor is substantially higher than in the case of a crack located in the homogenous pipe. Second, with regard to crack shapes, the circumferentially oriented cracks are practically identical regardless to the crack location if compared with the axial cracks. Third, the stress intensity factors of axially‐oriented cracks are approximately twice higher than in the case of circumferential cracks. This implies that the cracks are more likely to grow in an axial direction.

The results described in the paper can be used for estimation of critical crack length or for estimation of the critical applied inner pressure of medium transported in the pipe and are of paramount importance for service life estimations of polymer welded pipes in actual use.

The purpose of this paper is to investigate the tribological properties of a Cu–Cr–Zr alloy lubricated with acid rain.

The Cu 2.5 weight per cent–Cr-0.08 weight per cent–Zr alloy was produced in a vacuum induction furnace. The H₂SO₄ + H₂O, HNO₃ + H₂O and H₂SO₄ + HNO₃ + H₂O mixtures with pH of 5 were used as acid rain. Pure water was used as rain. The friction and wear properties of Cu–Cr–Zr alloy/American Iron and Steel Institute (AISI) 52100 steel couples lubricated with acid rain were investigated using a reciprocating ball-on-disc friction and wear tester (Optimol SRV, Germany). For investigating the properties of the alloy and wear scars, scanning electron microscopy, X-ray diffraction microscopy, energy dispersive X-ray spectrum, transmission electron microscopy and X-ray photoelectron spectroscope were used.

The wear rate of the Cu–Cr–Zr alloy lubricated with H₂O containing HNO₃ (pH = 5) was larger than pure water under the same conditions. The tribofilms containing Cu, Cr, Zr, S and N formed during sliding with acid rain, but corrosion also took place at that time.

The wear rate of the Cu–Cr–Zr alloy lubricated with H₂O containing HNO₃ (pH = 5) was larger than pure water, the wear and corrosion took place during sliding. As the trolley wires, the life of the Cu–Cr–Zr alloy was influenced by the environment.

The purpose of this paper is to review phytochemical potential of acacia and its associated health advantages. Acacia a moderate-sized, deciduous tree and recognised as health-promoting species because of availability of essential bioactive components. The bioactive compounds such as tannins, flavonoids, alkaloids, fatty acids and polysaccharides (gums) present in the plant parts of acacia, namely, bark, leaves, flowers, fruits, twigs and seeds, have medicinal value and thus are used to overlay the formulations of plant-based drugs and value-added foods.

Major well-known bibliometric information sources such as Web of Science, Scopus, Mendeley and Google Scholar were searched with keywords such as “nutrition value of acacia”, “bioactive compounds”, “health benefits”, “processing and safety” were chosen to obtain a database of 1,428 papers. The search considered papers in the English language from the past 18 years of publication in journals (2004–2022). The article selection process consisted of the screening of titles and abstracts, based on inclusion and exclusion criteria. Articles that did not have acacia components as a study objective were taken into consideration for exclusion. A final database of 87 scientific sources was made after sorting and classifying them according to different criteria based on topic relevance, country of origin and year of publication. Articles with other random descriptors were also searched to complement the discussion of the results obtained.

The literature reflected that acacia contains all necessary phytochemicals like polyphenols, flavonoids, terpenoids, glucosinolates, alkaloids and carotenoids along with essential macro, micro-nutrients. Furthermore, processing methods such as soaking, cooking, roasting and dehusking significantly reduced the anti-nutritional factors present in acacia seeds of different species. This review also focused on the processing methods that are used to eliminate or lower down the anti-nutritional factors from the seeds. Previous findings related to acacia plant parts with respect to food development are explored and mentioned.

This review emphasised mainly on recent studies that had been reported on ethnomedical acacia plants therapeutically, commercially and exponentially for further studies to increase the utilisation in food processing.

This paper aims to propose a simple, effective and environmentally benign method for the synthesis of commercially important pigment copper phthalocyanine (PC) blue has been developed using deep eutectic solvent (DES).

DES prepared from choline chloride and urea is used as a reaction medium, as well as a source of ammonia. The design of the experiment and factorial design study has proved that the milder reaction conditions with high yields and reusability of DES are the key features of the present study.

The synthesized pigment is obtained at milder reaction conditions with excellent yield, which can be seen from the design of experiments done for the optimization of results.

The synthesized pigment was used as a colorant in epoxy-based paint and in screen ink, which gave satisfactory results with respect to color values and stability.

The screen ink prepared was formulated considering environmental aspects to avoid the use of solvents. Biodegradable components were added to the colorant to make the ink environment friendly.

Reactions occur at moderate temperatures without affecting the time factor, thus, it saves energy. A simple, effective and environmentally benign method for the synthesis of commercially important copper PC has been developed using DES. After the first batch, DES synthesized can be reused as a reaction medium where only a stoichiometric amount of urea is to be added. Simple work up, high yield and purity are achieved.