Stability of double-diffusive natural convection in a vertical fluid layer

The stability of basic buoyant flow in a vertical fluid layer induced by temperature and solute concentration differences between the vertical boundaries is investigated. The linear dynamics of the perturbed flow is formulated as an eigenvalue problem and solved numerically by employing the Chebyshev collocation method. The validity of Squire's theorem is proved, and therefore, two-dimensional motions are considered. The neutral stability curves defining the threshold of linear instability and the critical values of the thermal Grashof number and wave number at the onset of instability are determined for various values of the Prandtl number P r, the solute Grashof number G S, and the Lewis number L e. The magnitude of the Prandtl number at which the transition from stationary to travelling-wave mode occurs can be either increased or decreased by tuning the values of G S and L e. For certain combinations of the parameters, there exist one or two closed disconnected travelling-wave neutral curves emphasizing the necessity of multiple thermal Grashof numbers to embark upon the stability of fluid flow, a result of contrast to that of the single-diffusive fluid layer. The mechanism of modal instability is deciphered by using the method of energy budget and four different modes of instability are identified, one of which is new and due entirely to the presence of solutal buoyancy. © 2021 Author(s)

Highly corrosion resistant platinum-rhodium alloy coating and its photocatalytic activity

A method of electroplating a platinum–rhodium (Pt-Rh) alloy coating with a specified composition on a metal substrate stainless steel (SS304) is presented in this article. The Pt-Rh bath consists of [Pt (NH3)2]HPO4, H2SO4 and Rh2(SO4)3. The Pt-Rh alloy electrodeposition coatings were characterized by different analytical methods such as Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). SEM images justify that coating is uniform in a 75% duty cycle. Energy Dispersive X-Ray Spectroscopy (EDX) confirms the presence of Pt and Rh in the coating. XRD confirms that crystalline size was reduced from 75% duty cycle to the rest of the PC’s coatings and DC (Direct current). The incorporation of the Pt-Rh metal ions was verified by EDX analyses. The corrosion behaviour of the developed Pt-Rh alloy coatings was evaluated in 0.1 M Na2SO4 solution using potentiodynamic polarization and electrochemical impedance techniques. The coating developed at PC-75% duty cycle possesses the highest corrosion resistance. A photocatalytic degradation study of Pt-Rh coating was conducted for Methylene Blue (MB) dyes under UV light radiation. The dye removal efficiency of Pt-Rh coated samples was 97% after irradiation and PC 75% duty cycles showed an exceptional dye degradation percentage compare to the DC coating source. All photocatalytic behaviour was controlled by using a UV–Vis spectrophotometer

Secondary Metabolite Production and Terpenoid Biosynthesis in Endophytic Fungi Cladosporium cladosporioides Isolated from Wild Cymbopogon martinii (Roxb.) Wats

: Endophytic fungi Cladosporium cladosporioides (F1-MH810309) and Cladosporium tenuissimum (F2-MN715834) from the leaf of wild Cymbopogon martinii (MT90507) were isolated and selected based on the persistent occurrence during different seasons of the year. They were identified based on the morphological features and molecular characterization (ITS sequence), and later deposited at NCBI. Phytochemical studies on F1, F2 and host extracts showed the presence of alkaloids, flavonoids, phenols, terpenoids and tannins. The GC-MS of F1 extract (control) under the axenic condition revealed compounds like hexadecane, heptadecane,2,4-Ditert-butylphenol, E-14 hexadecenal, geraniol, geranyl acetate and cubenol similar to the host. The GC-MS of F2 extract (control) revealed metabolites that were unique. Further, both F1 and F2 were cultured in the supplementation of different concentrations (5%, 10%, 15% and 20%) of the host plant extract (an-axenic condition). The GCMS of F1 extracts (test) exhibited good growth and showed the gradual increased production of terpenoid compounds whereas the F2 (test) did not show any growth. These compounds such as hyrdoxymenthol, nor-borneol, cedralacetate, α-cyclogeraniol, campesterol, β-cyclogeraniol, linalool oxide,2,3-boranediol, citronellyltiglate and 2,3-pinanediol were produced in a minor quantity and were known as biotransformed forms of the precursor compounds present in the host extract. In comparison, only F1 was able to produce terpenoids similar to the host species both in axenic and an-axenic conditions. Hence from the current study, the endophytic fungus F1 isolated from wild C. martinii for the first time can serve as a better resource for the bioprospection of an important terpenoid and its metabolites

Carbon nanotubes-based hydrogels for bacterial eradiation and wound-healing applications

Biocompatible nanomaterials have attracted enormous interest for biomedical applications. Carbonaceous materials, including carbon nanotubes (CNTs), have been widely explored in wound healing and other applications because of their superior physicochemical and potential biomedical properties to the nanoscale level. CNTs-based hydrogels are widely used for wound-healing and antibacterial applications. CNTs-based materials exhibited improved antimicrobial, antibacterial, adhesive, antioxidants, and mechanical properties, which are beneficial for the wound-healing process. This review concisely discussed the preparation of CNTs-based hydrogels and their antibacterial and wound-healing applications. The conductive potential of CNTs and their derivatives is discussed. It has been observed that the conductivity of CNTs is profoundly affected by their structure, temperature, and functionalization. CNTs properties can be easily modified by surface functionalization. CNTs-based composite hydrogels demonstrated superior antibacterial potential to corresponding pure polymer hydrogels. The accelerated wound healing was observed with CNTs-based hydrogels

A Study on Design Modification and Validation by Static and Dynamic Load Analysis of Sae-1020 and 40c8 Grade Steel Connecting Rods of 4-Stroke Petrol Engine

The connecting rod (CR) is one among the vital component of automotive engine of internal combustible type which sustains both static and fatigue loads and as a transmission member it converts linear movement of piston to circular movement of crank.Present literature describes about validating previously obtained results, to alter the design of the CR to increase its mechanical efficiency using finite element analysis, here outcomes of previous work have been extrapolated to 40C8 steel grade, by replacing SAE-1020 steel connecting rod of existing Pulsar 150cc, 4-stroke petrol engine and results have been compared for 40C8 and SAE-1020 steel grad. Present investigation has addressed two fields, primarily load stress analysis(static) and then dynamic load analysis of CR of two different materials. In this context, pulsar CR is procured and specimen is 3-D scanned, the stereolithographic data thus obtained is used to generate CAD model in NX-UG. Then the model is meshed using HYPERMESH thereafter stresses and fatigue life of CR for two different materials considered were found under given loading conditions using FEA software OPTISTRUCT. Finally, the results were interpreted using post-processor HYPERVIEW. Results of the analysis showed that the component of both steel grades was safe under given static loading conditions and dynamically it possessed infinite life and taking factor of safety and cost under consideration paper suggests the use 40C8 steel grade rather than SAE-1020 steel

Synthesis, Polytypism, and Dehydration Behaviour of Nitrate-Intercalated Layered Double Hydroxides of Ca and Al

Rapid precipitation of the hydroxide phase from a mixed metal nitrate solution comprising Ca2+ and Al3+ ions leads to the formation of a one-layered hexagonal polytype of [Ca-Al] layered double hydroxide. In contrast, slow precipitation results in a three-layered polytype of rhombohedral symmetry. Both polytypes comprise a stacking of positively charged metal hydroxide layers having the composition [Ca2Al(OH)6(H2O)2]+. The Ca2+ ions are seven coordinated with water molecules providing the seventh coordination. In the absence of any prior knowledge of the structure of the 1H polytype, translationengleiche and klassengleiche graphs were used to arrive at the space group and atom positions of the 1H polytype. Rietveld refinements of the structures of the two polytypes show that nitrate ions are intercalated in the interlayer gallery with its molecular plane inclined to the metal hydroxide layer. The angle of inclination in the 1H polytype (∼61°) is greater than that in the 3R polytype (∼30°). When the 1H polytype is completely dehydrated, the metal hydroxide layers undergo a rigid translation relative to one another resulting in (i) a 1H → 3R interpolytype transition, and (ii) the grafting of the nitrate ion to the metal hydroxide layer to satisfy the seventh coordination of the Ca2+ ion. The as-prepared 3R polytype has a mixed anion interlayer comprising nitrate and hydroxyl ions. On heating, this phase progressively loses crystallinity before decomposition

Real World Face Mask Detection using MobileNetV2 and Raspberry Pi

On March 12, 2020, Corona Virus Disease 2019 (COVID 19) was declared a global pandemic. Because of its quick spread from one person to another, this disease was thought to be more hazardous. Face masks have proven to be a good and effective way to stop the spread of COVID 19. Detection of Face Mask is a challenging problem. This paper proposes the method to solve this challenge by using deep learning. This work uses Multi-Task Cascaded Convolutional Neural Network (MTCNN) for detection and identification of face. MobileNetV2 is used as an object detector for mask detection. A total of 3833 images from different data sources were chosen for this work. This is later implemented using Raspberry Pi and pi cam, this setup transmits live video data from a remote location and hence the prediction of wearing mask is accomplished. The amount of information lost in the process is decreased gradually at 20th epoch is 0.0199. The accuracy by which the mask/no mask detection is increased

Cross Layer Design for Wi-Fi Sensor Network Handling Static and Dynamic Environment Using Local Automate Based Autonomic Network Architecture

In social activities with shared Wi-Fi needs to accommodate large number of users and effectively handle congestion. These are critical issues due to the presence of larger density nodal activity at nearby access points involving inter-technology interference. An interference involves a statistical approach in monitoring access points with its received errors. The received errors vary with frame reception at their fields like PHY, MAC headers and payloads. Local automate-based Autonomic Network Architecture a cross layer approach algorithm is proposed to channelize a frame reception and can effectively avoid inter-technology interference. This results in P2P communication at initial stages and can accommodate multiple mobile devices with varying signal strengths. The algorithm is deployed for a dynamic environment along with static clusters. The throughput of the entire network is increased by 20% because of

Phytochemicals, Antioxidant Profile and GC-MS Analysis of Ethanol Extract of Simarouba Glauca Seeds

Medicinal plants acted as traditional medicine from the ancient time and recognized as scientific medicine in modern days. Simarouba glauca is an Indian traditional medicinal plant commonly called as “Paradise Tree or Lakshmi Taru” used for its various medicinal properties. The current study was carried out to know the phytochemicals, antioxidant profile and Gas Chromatography- Mass Spectroscopy (GC-MS) of ethanol extract of the seed S. glauca. Qualitative analysis showed the presence of flavonoids and carbohydrates, lacked alkaloids, glycosides, steroids, triterpenoids and tannins. The total flavonoid, proanthocyanidin and phenol content were 25.20 ± 0.15mg quercetin equivalent/g extract, 57.08±1.51mg catechin equivalent/g extract and 41.75 ± 2.31mg gallic acid equivalent/g extract respectively. Antioxidants exhibited maximum 2, 2-Diphenyl- 1-picrylhydrazyl (DPPH) scavenging of 70% at 100 ?g/mL concentrations with an IC50 value 50.93?g/mL, decolourization potential of 2,2’-azino-bis - (3-ethyl benzthiazoline-6-sulfonic acid (ABTS) was 65% at 203.87?g/mL concentration and ferric reducing antioxidant potential (FRAP) assay exhibited Ascorbic Acid Equivalents (AAE/ml).The relative contents of the fatty acids were calculated with area normalization by GC-MS. Out of the ten fatty acids, four of them were Ethyl oleate (24.20%), Oleic acid (16.13%), 5-Hydroxymethylfurfural (12.69%) and Hexadecanoic acid ethyl ester (12.22%) and other six fatty acids were present less than 11

Evaluation of Anticancer Activity of Chaetomium Cupreum Extracts against Human Breast Adenocarcinoma Cell Lines

Background: Fungi are microorganisms which produce a wide variety of biologically active secondary metabolites that could be used for medicinal and pharmaceutical purposes. The Chaetomium cupreum is a natural source of different types of intracellular and extracellular pigments which exhibit various biological properties. Objectives: The main objectives of this study were to evaluate the anticancer property of C. cupreum extracts against human breast adenocarcinoma cell lines. Materials and Methods: The anticancer activity of different extracts of C. cupreum on human breast cancer cells was evaluated using MTT tetrazolium bromide assay. The measurement of mitochondrial membrane potential was evaluated using JC-1 fluorescent dye and reactive oxygen species (ROS) by 2,7-dichlorodihydrofluorescein diacetate dye. The partial purification and characterization of compound was done by chromatography and spectrometry methods. Results: It was found that ethyl acetate extract of C. cupreum showed significant cytotoxic activity against MCF-7 cells with IC50-40 and against MDA-DB231 cells with IC50-75 μg/ml concentration. In subfractions of ethyl acetate, the highest cytotoxic effect was shown by methanol subfraction (44.79%), followed by ethyl acetate subfraction (39.79%) and chloroform subfraction (37.07%) at the concentration of 25 μg/ml after 24 h. The anticancer activity of seco-chaetomugilin on MCF-7 cancer cells was 51.56% at the concentration of 25 μg/ml. In results, seco-chaetomugilin treatment increased depolarization of mitochondrial membrane potential to 16.45% at the concentration of 5 μg/ml and 32.25% at the concentration of 15 μg/ml as compared to 13.47% in untreated cells after 24 h. The results showed that the treatment of seco-chaetomugilin increased ROS generation to 19.6% at the concentration of 5 μg/ml and 26.2% at the concentration of 15 μg/ml as compared to 14% in untreated cells. Conclusion: These results showed that ethyl acetate extract and seco-chaetomugilin pigment induces mitochondria depolarization and ROS production, which leads to cell death. Thus, these results suggested that that pigment seco-chaetomugilin isolated from C. cupreum should further be studied for its anticancer activity on molecular level