Soft Computing Based Prediction of Unconfined Compressive Strength of Fly Ash Stabilised Organic Clay

The current study uses machine learning techniques such as Random Forest Regression (RFR), Artificial Neural Networks (ANN), Support Vector Machines Ploy kernel (SVMP), Support Vector Machines Radial Basis Function Kernel (SVMRBK), and M5P model tree (M5P) to estimate unconfined compressive strength of organic clay stabilized with fly ash. The unconfined compressive strength of stabilized clay was computed by considering the different input variables namely i) the ratio of Cao to Sio2, ii) organic content (OC), iii) fly ash (FAper) content, iv) the unconfined compressive strength of organic clay without fly ash (UCS0) and v) the pH of soil-fly ash (pHmix). By comparing the performance measure parameters, each model performance is evaluated. The result of present study can conclude the random forest regression (RFR) model predicts the unconfined compressive strength of the organic clay stabilized with fly ash with least error followed by Support Vector Machines Radial Basis Function Kernel (SVMRBK), Support Vector Machines Ploy kernel (SVMP), Artificial Neural Networks (ANN) and M5P model tree (M5P). When compared to the semi-empirical model available in the literature, all of the model predictions given in this study perform well. Finally, the RFR and SVMRBK sensitivity analyses revealed that the CaO/SiO2 ratio was the most relevant parameter in the prediction of unconfined compressive strength

Interaction of a dinuclear fluorescent Cd(II) complex of calix[4]arene conjugate with phosphates and its applicability in cell imaging

A triazole-linked hydroxyethylimino conjugate of calix[4]arene (L) and its cadmium complex have been synthesized and characterized, and their structures have been established. In the complex, both the Cd²⁺ centers are bound by an N₂O₄ core, and one of it is a distorted octahedral, whereas the other is a trigonal anti-prism. The fluorescence intensity of the di-nuclear Cd(II) complex is quenched only in the presence of phosphates and not with other anions studied owing to their binding affinities and the nature of the interaction of the phosphates with Cd²⁺. These are evident even from their absorption spectra. Different phosphates exhibit changes in both their fluorescence as well as absorption spectra to varying extents, suggesting their differential interactions. Among the six phosphates, H₂PO₄⁴⁻ has higher fluorescence quenching even at low equivalents of this ion, whereas P₂O₇⁴⁻ shows only 50% quenching even at 10 equivalents. The fluorescence quenching is considerable even at 20 ppb (0.2 μM) of H₂PO₄⁻, whereas all other phosphates require a concentration of 50–580 ppb to exhibit the same effect on fluorescence spectra. Thus, the interaction of H₂PO₄⁻ is more effective by ∼30 fold as compared to that of P₂O₇⁴⁻. Fluorescence quenching by phosphate is due to the release of L from its original cadmium complex via the formation of a ternary species followed by the capture of Cd²⁺ by the phosphate, as delineated based on the combination of spectral techniques, such as absorption, emission, ¹H NMR and ESI MS. The relative interactive abilities of the six phosphates differ from each other. The removal of Cd²⁺ is demonstrated to be reversible by the repeated addition of the phosphate followed by Cd²⁺. The characteristics of the ternary species formed in each of these six phosphates have been computationally modeled using molecular mechanics. The computational study revealed that the coordination between cadmium and –CH₂–CH₂–OH breaks and new coordination is established through the phosphate oxygens, and as a result the Cd²⁺ center acquires a distorted octahedral geometry. The utility of the complex was demonstrated in HeLa cells

Structure of a di-zinc complex of a bis-calix[4]arene conjugate and its sensing of cysteine among the amino acids

<p>A triethylene glycol di-imine locked triazole linked bis-calix[4]arene conjugate (<b>L</b>) and its Zn²⁺ complex [Zn₂<b>L</b>], were synthesised, characterised and the three-dimentional (3-D) structure of the complex was established by single crystal XRD. In this complex, the Zn²⁺ centre exhibits distorted tetrahedral geometry with N₂O₂ binding core. The complex showed selectivity towards cysteine (Cys) with greater sensitivity followed by histidine (His) among the naturally occurring amino acids studied based on fluorescence and absorption spectroscopy. The fluorescence quenching of the complex is much greater with Cys as compared to that of His. The detection limit of Cys is 650 ppb. Release of Zn²⁺ from its complex [Zn₂<b>L</b>] followed by its capture by –SH containing molecules was shown based on absorption and emission spectroscopy. This was also shown in one case by ¹H NMR spectroscopy.</p

Time- and concentration dependent reactivity of Cys, Hcy and GSH on the Diels Alder grafted conjugate of 1,3,5-tri-calix[6]arene to bring selectivity for Cys: Spectroscopy and microscopy, and its reactivity in cells

Herein we report the synthesis and characterization of 7-oxanorbornadiene (OND)-appended 1,3,5-tris conjugate of calix[6]arene (L2). L2 has been shown to exhibit selective reactivity toward cysteine (Cys) over homocysteine (Hcy) and glutathione (GSH) under stoichiometric conditions. The selectivity of L2 is attributed to the steric crowding of three Diels–Alder centers possessing OND units present on the calix[6]arene platform, while a control molecular system possessing only one such unit without the calix[6]arene platform (L1) does not show any selectivity toward Cys. While L2 exhibited spherical particles, its reactivity with Cys resulted in flowerlike morphological features, as revealed by scanning electron microscopy. However, the reaction with GSH did not result in any such morphological features, a result that is in agreement with that observed from fluorescence studies in solution. L2 has been shown to react with Cys present in HeLa and Jurkat E6 cells by fluorescence microscopy

Triazole-linked anthracenyl-appended calix[4]arene conjugate as receptor for Co(II): synthesis, spectroscopy, microscopy, and computational studies

A new triazole-linked anthracenyl-appended calix[4]arene-1,3-diconjugate (L) has been synthesized and characterized, and its single crystal XRD structure has been established. Binding properties of L toward different biologically relevant metal ions have been studied by fluorescence and absorption spectroscopy in ethanol. L exhibits selective recognition of Co²⁺ and can detect down to a concentration of 55 ppb (0.92 μM). The roles of the calix[4]arene platform as well as the preorganized binding core in L’s selective recognition have been demonstrated by studying appropriate control molecules. The mode of binding of L with Co²⁺ has been modeled both by DFT and MD computational calculations. L and its Co²⁺ complex could be differentiated on the basis of the nanostructural features observed in AFM and TEM

Supramolecular complexation of biological phosphates with acyclic triazolium-linked anthracenyl-1,3-diconjugate of calix[4]arene: synthesis, characterization, spectroscopy, microscopy and computational studies

A triazolium-anthracenyl calix[4]arene conjugate (L) was synthesized by methylating the precursor triazole derivative and then characterized. The potential of the cationic L to differentiate nucleoside triphosphates (NTPs) from their mono- and diphosphates was demonstrated. Due to its unique combination of arms with the calix-platform, a fluorescence enhancement was observed for L with all the NTPs, whereas there is no report with such enhancement being exhibited in case of all the NTPs. This has been supported by the aggregation of L observed from microscopy. Selectivity of L towards NTPs over other phosphates was a result of specific weak interactions, namely, ion–ion, hydrogen bonding and π⋅⋅⋅π, present in the 1:2 complex of L and NTPs (based on ESI MS), which were absent in their congener-phosphates as delineated by NMR and computational studies. Thus, L stands as a unique receptor for NTPs

A fluorescent di-zinc(II) complex of bis-calix[4]arene conjugate as chemosensing-ensemble for the selective recognition of ATP

<div><p>A triethylene glycol di-imine locked triazole linked bis-calix[4]arene conjugate <b>L</b> has been synthesised and characterised. Conjugate <b>L</b> exhibits high fluorescence enhancement towards Zn²⁺ among the 13 metal ions studied down to a lower detection limit of ∼12 ppb. The absorption and visual colour change experiments differentiated the Zn²⁺ from the other metal ions studied. The isolated zinc complex, [Zn₂<b>L</b>] has been used as a chemo-sensing ensemble for the recognition of anions based on their binding affinities towards Zn²⁺. [Zn₂<b>L</b>] was found to be sensitive and selective towards phosphate-bearing species and in particular to adenosine triphosphate (ATP^2 −) among the other 20 anions studied as observed based on the changes occurred in the fluorescence intensity. The selectivity of the ATP^2 − has been shown on the basis of the changes observed in the emission and absorption spectral studies. The lowest detectable concentration for ATP^2 − with the chemo-sensing ensemble [Zn₂<b>L</b>] is 348 ppb in methanol. The fluorescence quenching by the phosphate-based anions has been modelled by molecular mechanics studies and found that the anions possessing two or more phosphate moieties can only bridge between the two zinc centres, and hence those possessing only one phosphate moiety (H₂PO₄⁻ and AMP^2 −) are ineffective.</p></div

Triazole Linked Picolylimine Conjugate of Calix[6]arene as a Sequential Sensor for La³⁺ Followed by F^–

A new 1,3,5-tris-triazole linked picolylimine conjugate of calix[6]arene (<b>L</b>) has been shown to be selective toward La³⁺ by <i>turn on</i> fluorescence with ∼70-fold enhancement and emits blue, with a minimal detection limit of 65 ± 5 ppb (490 nM). The species of recognition has been modeled computationally to have a monocapped twisted square antiprism with a N₆O₃ binding core about La³⁺. The <i>in situ</i> complex of <b>L</b> with La³⁺ recognizes F^– via fluorescence quenching. The reversible response of sensing La³⁺ and F^– sequentially by <b>L</b> has been demonstrated