Strength Of Medium Research Articles

Kinetics and mechanistics steps to the electron transfer reaction of peroxo-bridged binuclear cobalt(III) complex of succinimide by glycine in aqueous acidic medium

ABSTRACT. The kinetics and mechanistic steps to the electron transfer reaction of the peroxo-bridged binuclear cobalt(III) complex of succinimide [(suc)(en)2Co(O2)Co(en)2(suc)2+] hereafter called peroxo-bridged dicobalt(III) complex ‘[Co(O2)Co2+]’ by glycine have been carried out spectrophotometrically at λ = 420 nm and T = 26 ± 1 oC, [H+] = 1 x 10-3 M and ᶙ = 0.5 M (NaCl) in aqueous acidic medium. The reaction was found to be first order with respect to [Co(O2)Co2+] and [(Gly] and experimental data indicates a second-order overall. The reactions obeyed the general rate law: (d[Co(O2)Co2+]/dt) = (a +b)[H+])[Co(O2)Co2+][Gly]. Varying hydrogen ion concentration accelerated the reaction rate and shows first-order dependence while the reactions also affected by changes in the ionic strength of the reaction medium by giving a non-negative salt effect in the course of the reaction. Free radicals were not detected in the reactions. Spectroscopic investigation and Michaelis-Menten plots suggest the absence of intermediate complex formation. The experimental result obtained in this system is concluded in favor of the outer-sphere mechanism.
 
 KEY WORDS: Cobalt(III) complex, Kinetic, Electron transfer, Spectroscopic, Mechanistic steps, Michaelis-Menten, Glycine
 
 Bull. Chem. Soc. Ethiop. 2021, 35(2), 425-434.
 DOI: https://dx.doi.org/10.4314/bcse.v35i2.15

Complex Equilibria and Distribution of Metal (II) Ions with Biologically Active Chelating Agents in Aqueous and Aqueous-organic Media

An understanding of the principles of complex equilibria and species distribution in different solutions is important in expounding and correlating the interaction of different ligands with different metal ions in complex formation. Therefore, acid-base equilibria involved in the formation of binary and ternary complexes of Co (II), Cu (II) and Pb (II) with methionine (Met) and uracil (Urc) have been determined by potentiometric titration technique. The stability constants of the complexes were evaluated at 35 ± 0.1°C and 0.02 M ionic strength (kept constant with NaNO3) in aqueous and organic-aqueous media. The species distribution in solutions as a function of pH was determined using the Hyss program. The stability of the ternary complexes relative to the corresponding binary complexes of the secondary ligand is measured in terms ΔlogK and % RS values. The ternary complexes are observed to be more stable than binary complexes in the media except for [CuMetUrc] ternary complex in organic-aqueous medium where the ternary complex is less stable than the binary complex of the uracil. The overall stability of the ternary complexes was higher in organic-aqueous system than aqueous system. The stability of the complexes was found to be correlated with the covalent index of the metal ions and Jahn Teller distortion. pH-studies of these systems revealed an increase in the concentrations of the ternary complexes with increase in pH. The formation of binary complexes was shown to be favoured in physiological pH range (3-7) while that of the ternary complexes is observed to be favoured in the pH range 5-10.

Unraveling the Eclipse Mechanism of a Binary Millisecond Pulsar Using Broadband Radio Spectra

Abstract The frequency dependent eclipses of the radio emission from millisecond pulsars in compact binary systems provide an opportunity to understand the eclipse mechanism and to determine the nature of the eclipsing medium. We combine multifrequency observations from the upgraded Giant Metrewave Radio Telescope and model the broadband radio spectrum in the optically thick to thin transition regime to constrain the eclipse mechanism. The best-fit model to the eclipse phase spectra favors synchrotron absorption by relativistic electrons. We are able to strongly constrain the frequency of onset of the eclipse to 345 ± 5 MHz, which is an order of magnitude more precise than previous estimates. The dependence on the magnetic field strength of synchrotron absorption allowed us to estimate the magnetic field strength of the eclipse medium to be ∼13 G, which is very similar to the values obtained by considering a pressure balance between the incident pulsar wind and the stellar wind of the companion. Applying this method to other millisecond binary pulsars will enable us to determine if the eclipse mechanisms are all the same and also estimate the wind and magnetic field properties of the companion stars. The method could also be applied to other systems where pulsars interact with companion winds in binary systems and in all cases it will lead to a better understanding of the evolutionary processes.

Double-diffusion convective biomimetic flow of nanofluid in a complex divergent porous wavy medium under magnetic effects.

We explore the physical influence of magnetic field on double-diffusive convection in complex biomimetic (peristaltic) propulsion of nanofluid through a two-dimensional divergent channel. Additionally, porosity effects along with rheological properties of the fluid are also retained in the analysis. The mathematical model is developed by equations of continuity, momentum, energy, and mass concentration. First, scaling analysis is introduced to simplify the rheological equations in the wave frame of reference and then get the final form of equations after applying the low Reynolds number and lubrication approach. The obtained equations are solved analytically by using integration method. Physical interpretation of velocity, pressure gradient, pumping phenomena, trapping phenomena, heat, and mass transfer mechanisms are discussed in detail under magnetic and porous environment. The magnitude of velocity profile is reduced by increasing Grashof parameter. The bolus circulations disappeared from trapping phenomena for larger strength of magnetic and porosity medium. The magnitude of temperature profile and mass concentration are increasing by enhancing the Brownian motion parameter. This study can be productive in manufacturing non-uniform and divergent shapes of micro-lab-chip devices for thermal engineering, industrial, and medical technologies.

Aloe vera L. (Asphodelaceae): Supplementation of in-vitro culture medium with Aloe vera gel for production of genetically stable plants

As in vitro culture environments can be mutagenic, it's challenging to produce true-to-true type plants from meristems. Therefore, the present study aimed to devlop an efficient protocol for micropropagation from shoot tip explants of medicinally important Aloe vera using different concentrations of A. vera leaf gel (AvG) as organic supplement to the culture media. Assessment of the genetic stability of A. vera in vitro multiplied plants compared to the donor plant is one of the most important pre-requisites especially before its use for commercial and medicinal purposes. For shoot multiplication, the highest number of axillary shoots recorded was 13.27 ±5.11 with an average length of 2.21 ±0.84 cm on M3 medium (MS + 0.2 mg L−1 of β-indole butyric acid (IBA) + 3 mg L−1 benzylamino-purine (BA) + 5% AvG). All three strength of MS medium (1, 1/2, 1/4) with different concentrations of AvG resulted in 100% root induction after 4 weeks of culture. All the rooted microshoots (100%) were successfully acclimatized. To provide a reliable conclusion on its nutritive supply to MS medium, the total phenolic (TPC), condensed tannins (TTC), flavonoid (TFC), and flavonol (TFlC) content as well as the antioxydant activity of AvG were investigated. TPC and TTC values were found to be 31.02 ± 0.46 μg gallic acid equivalent mg−1 of extract and 4.00 ± 0.96 μg catechin equivalent mg−1 of extract, respectively while TFC and TFlC were 13.58 ± 0.84 and 9.75 ± 0.58 μg rutin equivalent mg−1 of extract, respectively. The results of antioxydant activity of AvG following DPPH, FRAP and ABTS assays were equal to 12.50 ± 0.89; 49.59 ± 2.07 and 64.93 ± 3.23 µmol Trolox equivalent mg−1 of extract, respectively which may explain the positive role of AvG as supplement.The genetic stability of in vitro propagated A. vera plants was evaluated using 10 inter simple sequence repeat (ISSR), 10 start codon targeted (SCoT) and 10 simple sequence repeat (SSR) markers. Out of these, 5 ISSR, 3 SCoT and 6 SSR primers produced resolvable, reproducible and scorable bands. ISSR primers generated 32 amplification products ranging from 200 to 1040 bp in size with a mean number of 6.4 bands while SCoT primers generated 33 amplicons with an average of 11 bands in the range of 160–2410 bp. In the SSR products, 6 bands were observed, each primer produced one band ranging from 410 to 720 bp. All banding profiles were monomorphic proving that the stability of the micropropagated A. vera plants was maintained. This study proved the suitability of supplementing in vitro culture media with AvG to enhance direct regeneration through shoot tip explants of A. vera for large scale micropropagation applications.

Colored Surfaces Made of Synthetic Eumelanin.

The polymerization of 3,4-dihydroxy-L-phenylalanine leads to a carboxylic acid-rich synthetic melanin-like material (poly-L-DOPA). Synthetic melanin most resembles natural eumelanin in chemical structure. However, its deposition on surfaces leading to colored surfaces by interference is not as easy to accomplish as in the case of the preparation of colored surfaces by dopamine hydrochloride polymerization. This study deals with the preparation of new colored surfaces made from poly-L-DOPA displaying vivid colors by interference. These surfaces were obtained by depositing thin films of poly-L-DOPA on a reflective silicon nitride substrate. A high ionic strength in the polymerization medium was essential to accomplish the coating. The effect of ionic strength on the resulting surfaces was studied via reflectance, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The refractive index was determined by ellipsometry, and was nearly constant to 1.8 when λ > 650 nm. In the visible spectral region, the imaginary part of the refractive index becomes relevant. The refractive index in the visible wavelength range (400–600 nm) was in the range 1.7–1.80.

Marble Waste Sludges as Effective Nanomaterials for Cu (II) Adsorption in Aqueous Media.

This study evaluated the waste generated by a Spanish marble-producing company as adsorbent for the removal of copper (Cu [II]) from aqueous media. Six marble waste sludge samples were studied, and the following operational parameters were analyzed in discontinuous regime, including pollutant concentration, pH, temperature, nature of aqueous medium, and ionic strength. The applicability of the adsorbent material was assessed with experiments in both continuous and discontinuous regimes under close-to-real-life conditions. A pseudo-second order model yielded a better fit to the kinetic data. Application of the intraparticle diffusion model revealed two well-differentiated adsorption stages, in which the external material transfer is negligible and intraparticle diffusion is the controlling stage. The equilibrium study was better fitted to a Freundlich-type isotherm, predicting elevated maximum adsorption values (22.7 mg g−1) at a relatively low initial Cu (II) concentration (25 ppm), yielding a highly favorable chemisorption process (n >> 1). X-ray fluorescence study identified calcite (CaCO3) as the main component of marble waste sludges. According to X-ray diffraction analysis, Cu (II) ion adsorption occurred by intercalation of the metallic cation between CaCO3 layers and by the formation of surface complexes such as CaCO3 and Cu2(CO3)(OH)2. Cu (II) was more effectively removed at medium pH, lower temperature, and lower ionic strength of the aqueous medium. The salinity and dissolved organic matter in surface, ground-, and waste-waters negatively affected the Cu (II) removal process in both continuous and discontinuous regimes by competing for active adsorption sites. These findings demonstrate the applicability and effectiveness of marble-derived waste sludges as low-cost and readily available adsorbents for the treatment of waters polluted by Cu (II) under close-to-real-life conditions.

Micropropagation of Rose (Rosa Hybrida) Using Invitro Technique by Natural Hormone

In recent years ,several Micropropagation technique has been established, to make some improved method of crop yield production the natural hormone from other plant species were selected for the beneficial result in the plant species. The Micro propagation technique is carried out in Rosa hybrida explant by providing the different natural shooting and rooting hormone in three different compositions with the half strength of MS medium , it is to predict the ability of which natural hormone is being utilized by the nodal explant of Rosa hybrida. The three different natural shooting and rooting hormone are Aloe vera gel extract and the tender coconut water with 50 ml and 100 ml and 150 ml of concentration in half strength MS media and the Cinnamon powder alone taken in the .5 g,1g and 1.5 g of concentration in half strength MS media due to the powdery form. These were proceeded in aseptic condition of propagation as a result it has been noticed that among the three natural hormone the remarkable growth has been found in the tender coconut water provided nodal segment in all the three concentration .This article has a goal to promote the use of the natural rooting role in the plant breeding industry.

Modeling shear strength of medium- to ultra-high-strength concrete beams with stirrups using SVR and genetic algorithm

This paper presents a data-driven machine learning approach of support vector regression (SVR) with genetic algorithm (GA) optimization approach called SVR-GA for predicting the shear strength capacity of medium- to ultra-high strength concrete beams with longitudinal reinforcement and vertical stirrups. One hundred and forty eight experimental samples collected with different geometric, material and physical factors from literature were utilized for SVR-GA with fivefold cross validation. Shear influence factors such as the stirrup spacing, the beam width, the shear span-to-depth ratio, the effective depth of the beam, the concrete compressive and tensile strength, the longitudinal reinforcement ratio, the product of stirrup ratio and stirrup yield strength were served as input variables. The simulation results show that SVR-GA model can achieve highest accuracy in shear strength prediction based on testing set with a coefficient of determination (R2) of 0.9642, root mean squared error of 1.4685 and mean absolute error of 1.0216 superior to that for traditional SVR model with 0.9379, 2.0375 and 1.4917, which both perform better than multiple linear regression and ACI-318. Furthermore, the sensitivity analysis reveals the most important variables affecting the result of shear strength prediction are shear span-to-depth ratio, concrete compressive strength, reinforcement ratio and the product of stirrup ratio and stirrup yield strength. Three-dimensional input/output maps are employed to reflect the nonlinear variation of the shear strength with the two coupling variables. All in all, the proposed SVR-GA model can achieve excellent accuracy in prediction the shear strength of medium- to ultra-high strength concrete beams with stirrups in comparison with results obtained by traditional SVR, MLP and ACI-318.

Effect of Carbon Chain Length, Ionic Strength, and pH on the In Vitro Release Kinetics of Cationic Drugs from Fatty-Acid-Loaded Contact Lenses.

This paper explores the use of fatty acids in silicone hydrogel contact lenses for extending the release duration of cationic drugs. Drug release kinetics was dependent on the carbon chain length of the fatty acid loaded in the lens, with 12-, 14- and 18-carbon chain length fatty acids increasing the uptake and the release duration of ketotifen fumarate (KTF) and tetracaine hydrochloride (THCL). Drug release kinetics from oleic acid-loaded lenses was evaluated in phosphate buffer saline (PBS) at different ionic strengths (I = 167, 500, 1665 mM); the release duration of KTF and THCL was decreased with increasing ionic strength of the release medium. Furthermore, the release of KTF and THCL in deionized water did not show a burst and was significantly slower compared to that in PBS. The release kinetics of KTF and THCL was significantly faster when the pH of the release medium was decreased from 7.4 towards 5.5 because of the decrease in the relative amounts of oleate anions in the lens mostly populated at the polymer–pore interfaces. The use of boundary charges at the polymer–pore interfaces of a contact lens to enhance drug partition and extend its release is further confirmed by loading cationic phytosphingosine in contact lenses to attract an anionic drug.

Determining physico-chemical parameters for high strength ambient cured fly ash-based alkali-activated cements

High strength ambient cured alkali-activated cement was developed from original Class-F (ASTM) fly ash using 1:2.5 mass ratio of 16 molar sodium hydroxide and sodium silicate liquid activator with solution to solid binder ratio of 0.36 for in-situ cast application. Graded strength of high, medium and low in the range of 60–103, 30–56 and ≤ 20 MPa were obtained using mono-component original fine, medium and coarse sized fly ashes respectively. The inclusion of 35 wt% GGBS in the medium sized Class-F fly ash improved the strength from 45 MPa to 60 MPa while 100% GGBS showed higher strength of 81 MPa. Chemically, CaO/SiO2 ratio in the composition influenced the fresh and hardened properties of alkali-activated fly ash/GGBS cements. For instance, in the Class-F fly ash (Si/Al=1.55-1.99) based compacts with CaO/SiO2 ratio ≤ 0.03, the strength improved with increasing atomic Al/(Na + K) ratio. Conversely strength decreased with increasing Al/(Na + K) ratio in bi-component fly ash and GGBS based alkali-activated cements where CaO/SiO2 ratio is higher in between 0.17-0.75. Interestingly Si-dissolution from subcrystalline silica or fine quartz from mechanically activated Class-C fly ash did not improve strength. Lignite ash with high specific surface area as obtained in low temperature combustion did not react with high pH alkaline solution indicating need for vitreous aluminosilicate glass. X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic analyses show that plagioclase and C-S-H were the reaction products responsible for strength gain in ambient cured alkali-activated fly ash/GGBS cements.

Numerical Simulation Study on Compression Characteristics of Gravelly Soil Mixture Based on Soft Servo Method

Because of complex mechanical properties and deformation mechanism, gravel soil mixture is an important medium of concern in the field of geotechnical engineering. Based on the continuous-discontinuous coupling algorithm formed by the structure shell elements and the particle discrete element method (PFC3D), the soft servo loading of the sample is realized, and the typical triaxial compression test data are used to calibrate mesoscale parameters. Furthermore, the numerical tests under different rock contents and confining pressure are carried out. The change rule of shear strength of mixed medium is discussed. It shows that the continuous-discontinuous coupling algorithm achieves a good effect in reflecting the deformation process. Under the mechanism of the flexible servo, the failure mode of the sample takes on drum-failure mode, and the internal of the damaged sample forms an obvious asymmetric X-shaped shear band. With the increase of stone content, the internal friction angle and cohesive force distribution of the sample have certain discreteness, but on the whole, the internal friction angle and cohesive force increase with the increase of stone content. The results can provide a reference for the parameter determination of mixed mediums such as gravel soil.

Research on uniaxial compression of jointed rock mass based on numerical simulation

Jointed rock mass is a material with anisotropic strength and coexistence of continuous and discontinuous media. In order to study the mechanical behavior of rock mass impacted by the spatial distribution of joints, RFPA2D, which is a discrete element geotechnical engineering simulation, is employed in this paper. Based on the basic rock mechanical parameters obtained from uniaxial compression experiment, the influence of joint inclination angle on rock strength and strain path is explored. The simulation results show that: Cracks will cause large initial damage to the rock mass, resulting in a significant decrease in the peak strength of the specimen compared with the intact rock mass. Meanwhile, it decreases the stage of elastic deformation, and it has the strongest impact to strain path when joint angle equals to 90°.

Solvent and moleculer structure effects on acidity strength in non-aqueous medium

The acidic properties of ten 3-alkyl(aryl)-4-[3-hydroxy-4-methoxy benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives were investigated. In this study, isopropyl alcohol and tert‐butanol were used as an amphiprotic solvent. Aceton and N,N‐ dimethylformamide (DMF) were preferred as a dipolar aprotic solvent. Compounds were titrated with tetrabuthylamonnium hydroxide (TBAH) in isopropyl alcohol and titrimetric analyses were used potentiometric method determining the end-points, half-neutralization method determining acidity. Typical S-shaped titration graphs excepted were determined. The acidity strengths of 4,5-dihydro-1H-1,2,4-triazol-5-one derivatives in amphiprotic and dipolar aprotic solvents were calculated using tables and graphs. The pKa values obtained in the solvents were found to be differentiated. The effects of solvent, molecular structure, autoprotolysis constant dielectric constant, and leveling‐differentiation effects of the solvents upon acidity strength of the compounds were discussed.

Modeling and optimizing in vitro seed germination of industrial hemp (Cannabis sativa L.)

In vitro seed germination of cannabis as the first physiological stage in the plant life cycle is not only important for studying factors affecting cultivation conditions but also crucial for obtaining juvenile tissue as a potential explant for different in vitro procedures. On the other hand, in vitro seed germination is a multi-variable biological process that can be influenced by genetic (genotype) and physical factors (medium composition and environmental conditions). Therefore, a powerful mathematical methodology such as artificial neural networks (ANNs) is well suited to analyze the data and optimize the conditions this complex system. The current study was aimed to evaluate the effect of different types and concentrations of carbohydrate sources (sucrose and glucose) as well as different strengths of DKW (Driver and Kuniyaki Walnut) and mMS (Murashige and Skoog Medium, Van der Salm modification) media on seed germination indices as well as morphological features of in vitro-grown cannabis seedlings by using three ANNs including multilayer perceptron (MLP), radial basis function (RBF), and generalized regression neural network (GRNN). The GRNN model displayed higher predictive accuracy (r2>0.70) in both training and testing sets for all germination indices and morphological traits in comparison to RBF or MLP. Moreover, non-dominated sorting genetic algorithm-II (NSGA-II) was subjected to the GRNN to find the optimal type and level of media and carbohydrate source for obtaining the best seed germination indices (germination rate and mean germination time). According to the optimization process, 0.43 strength mMS medium supplemented with 2.3 % sucrose would result in the best outcomes. This result showed that a moderate level of salts existing in culture media (0.43 strength of mMS medium) supplemented with a moderate level of sucrose (2.3 %) can improve in vitro seed germination of hemp. The results of a validation experiment revealed that there was a negligible difference between the experimental data and the optimized result. Therefore, GRNN-NSGA-II provided an accurate prediction of seed germination and can likely be employed to optimize different factors involved in in vitro culture of this multi-purpose crop.

Mass Propagation of Nauclea diderrichii (de Willd. & Th. Dur) Merr. Seedlings through Tissue Culture Technique

Nauclea diderrichii is a tree species of economic importance. However, its plantation establishment is limited by inadequate seedling production. Hence, there is ample scope of tissue culture for its mass propagation. Its in vitro plantlets development as affected by media strengths indicated that 100 % seed germination was obtained in full MS basal medium while the least (3.35 %) was from quarter-strength at 8 Weeks after inoculation (WAI). The effects of BAP and NAA assessed on the growth of its sub-cultured plantlets showed that highest number of leaves (17) and adventitious shoots (3) were obtained from MS basal medium supplemented with 0.1 mg/l BAP only. Whereas, highest shoot length (3.61 cm) and average number of roots (5/plantlet) were obtained from the same medium without hormone(s) at 8 WAI. Further sub-culturing into MS with 0.05 mg/l NAA resulted into plantlets having optimum shoot and massive root growth ready for acclimatization in 6 WAI. The plantlets were successfully acclimatized using coconuthusk/ topsoil mixture with 90 % survival.
 Plant Tissue Cult. & Biotech. 31(1): 51-60, 2021 (June)

In vitro Micropropagation of Pomegranate (Punica granatum L.) Derived from Cotyledon

A high frequency in vitro plant regeneration of pomegranate was established on MS medium supplemented with different concentrations and combinations of plant growth regulators. As explant cotyledons were employed for this study. Ninety percent of the cultured explants responded to form shoots from 30 days old in vitro raised seedlings after 90 days of culture initiation in MS containing 1.0 mg/l IBA + 0.1 mg/l NAA. The average number of shoots per explant was 10.0 ± 2.20, shoot length of 12.0 ± 2.40 cm, node per regenerated shoot was 9.0 ± 1.60 and the leaf number was14.0 ± 1.40. Well developed shoots were cultured on half strength of MS medium supplemented with 0.5 mg/l IBA, in which 90% shoot induced roots implanted after one month. The average number of root per shoot was 8.0 ± 0.90 and the average root length of 6.5 ± 0.40 cm was observed in this medium. Eighty percent plantlets were survived in the outdoor condition during the acclimatization period of seven days.
 Plant Tissue Cult. & Biotech. 31(1): 61-69, 2021 (June)

Nigerian press under political siege: social media salvage of press freedom in Fani-Kayode versus Charles of Daily Trust

Fani-Kayode versus Eyo Charles of Daily Trust saga compels research attention as it exhumed a new perspective to press struggle under political bondage in Nigeria. Nigerian journalists have been thrown into the towel on several occasions in the struggle to uphold press freedom as some were brutalised, molested, suppressed, bribed, or even intimidated with impunity while carrying out their democratic roles. The agitation not only for press freedom, the degree of independence that put the fourth estate of the realm on uninfluenced reportorial vantage but also a clear separation of media agenda power from politics of bankrolling beeps a light of redemption through social media rendition. Contents of mainstream and social media (Facebook, Twitter & YouTube) in the case of Fani-Kayode versus Charles were subjected to empirical analysis to test media efforts towards self-actualisation from political insubordinations. The data show that social media reign a significant influence on the salvage of press freedom taking “Who bankrolls your tour of states” tussle as a significant variable to compare the agenda and framing patterns the case under study enjoyed on social and mainstream media. The study found out that the media agenda might that recouped the press freedom from political intimidation and disparagement in the case under study was more than 90% social media strength. The mainstream media and their journalists got the inspiration for their belated actions from the battle already won through the social media agenda.

The Effect of MS Media Strength and Cytokinin in the Induction of Shoots from Shoot Tip Explants of Australian Finger Lime (Citrus australasica cv. Tasty Green)

The Australian Finger Lime (Citrus australasica) is a type of citrus from the Rutaceae family, endemic to the east coast of Australia. The finger lime, loaded with numerous vitamins and renders a unique taste, has also been backed by science to contain essential amounts of antioxidants that are beneficial for cell protection, immune response, cancer prevention, ageing, arthritis and prevention of kidney stones. Current propagation attempts still rely on conventional methods that are less efficient and resulted in the slow establishment of farms for finger lime especially for commercialization purposes. This study focuses on the induction of shoots from shoot tip explants using 6-Benzylaminopurine (BAP) and Kinetin. Aseptic explants were inoculated into Murashige and Skoog (MS) medium of full-strength and half-strength followed by full-strength MS media supplemented with different concentrations of BAP and Kinetin. Results obtained in this study showed no significant differences in terms of the number of axillary shoots produced between explants cultured in full and half-strength MS media. However, the highest number of shoots and increment in shoot length were obtained from MS media supplemented with 2.0 mg/L BAP with the values 1.80 ± 0.27 and 2.56 ± 0.36 cm, respectively. In conclusion, MS media supplemented with 2.0 mg/L BAP was found optimal in the induction of shoots and shoot elongation of C. australasica cv. Tasty Green.

An explicit formulation of the macroscopic strength criterion for porous media with pressure and Lode angle dependent matrix under axisymmetric loading

This paper aims to propose an explicit formulation of the macroscopic strength criterion for porous media with spherical voids. The matrix is assumed rigid and perfectly plastic with yield surface described by the three-parameter strength criterion, which is Lode angle and pressure dependent and capable of accounting for distinct values of the uniaxial tensile strength, uniaxial compressive strength (UCS) and equal biaxial compressive strength (eBCS). An exact upper bound of the macroscopic strength is derived for porous media subjected to purely hydrostatic loading. Besides, an estimate of the macroscopic strength profile of porous media under axisymmetric loading is obtained in parametric form. Moreover, a heuristic strength criterion in explicit form is further developed by examining limit cases of the parametric strength criterion. The developed strength criteria are assessed by finite-element based numerical solutions. Compared with the parametric strength criterion which involves cumbersome functions, the heuristic one is convenient for practical applications. For specific values of the matrix's strength surface, the proposed heuristic strength criterion can recover the well-known Gurson criterion. The present work also addresses the effect of the ratio of matrix's eBCS to UCS on the macroscopic strength of porous media. For matrix with distinct values of eBCS and UCS, neglecting the difference between eBCS and UCS would result in an underestimation of the macroscopic strength, especially when the pressure is large.