Constant Values Research Articles

Radiation exposure and screening yield by digital breast tomosynthesis compared to mammography: results of the TOSYMA Trialbreast density related.

The randomized TOmosynthesis plus SYnthesized MAmmography (TOSYMA) screening trial has shown that digital breast tomosynthesis plus synthesized mammography (DBT + SM) is superior to digital mammography (DM) in invasive breast cancer detection varying with breast density. On the other hand, the overall average glandular dose (AGD) of DBT is higher than that of DM. Comparing the DBT + SM and DM trial arm, we analyzed here the mean AGD and their determinants per breast density category and related them to the respective invasive cancer detection rates (iCDR). TOSYMA screened 99,689 women aged 50 to 69 years. Compression force, resulting breast thickness, the calculated AGD obtained from each mammography device, and previously published iCDR were used for comparisons across breast density categories in the two trial arms. There were 196,622 exposures of 49,227 women (DBT + SM) and 197,037 exposures of 49,132 women (DM) available for analyses. Mean breast thicknesses declined from breast density category A (fatty) to D (extremely dense) in both trial arms. However, while the mean AGD in the DBT + SM arm declined concomitantly from category A (2.41 mGy) to D (1.89 mGy), it remained almost unchanged in the DM arm (1.46 and 1.51 mGy, respectively). In relative terms, the AGD elevation in the DBT + SM arm (64.4% (A), by 44.5% (B), 27.8% (C), and 26.0% (D)) was lowest in dense breasts where, however, the highest iCDR were observed. Women with dense breasts may specifically benefit from DBT + SM screening as high cancer detection is achieved with only moderate AGD elevations. TOSYMA suggests a favorable constellation for screening with digital breast tomosynthesis plus synthesized mammography (DBT + SM) in dense breasts when weighing average glandular dose elevation against raised invasive breast cancer detection rates. There is potential for density-, i.e., risk-adapted population-wide breast cancer screening with DBT + SM. Breast thickness declines with visually increasing density in digital mammography (DM) and digital breast tomosynthesis (DBT). Average glandular doses of DBT decrease with increasing density; digital mammography shows lower andmore constant values. With the smallest average glandular dose differencein dense breasts, DBT plus SM had thehighest difference in invasive breast cancer detection rates.

Synthesis and characterization of flexible CaCoAlFe2O4 based microwave substrate for triband polarization-insensitive metamaterial absorber

This study investigated CaxCo(0.90-x)Al.01Fe2O4 nanoparticle synthesized using the sol–gel synthesis method to achieve a flexible substrate with a high dielectric constant value. The XRD, FESEM, and dielectric characteristic is analyzed to explore the performance of the suggested Ox Wheels-shaped (OWS) metamaterial absorber unit cell. The X-ray diffraction (XRD) analysis found significant peaks at 30° (318), 33° (176), 35° (794), 43° (232), 53° (116), 57° (256), 62° (304), and 74° (126) planes. The dielectric constant values of the prepared nanomaterial materials are 4.52 (X = 90 %), 4.73 (X = 60 %), and 5.07 (X = 30 %) due to the deviations in raw material compositions. The prepared, flexible substrate is used in the anticipated OWS metamaterial absorber unit cell, and analysis has been widely considered and continuously concerned due to their excellent ultra-thin thickness, lightweight, and high absorbance resonance features. The predicted structure reached S21 response at 3.47 GHz, 7.05 GHz, and 10.76 GHz with the magnitude of −24.11 dB, −17.07 dB, and −19.19 dB, respectively, using CST simulation software. The absorber prototype is measured for further investigation within the frequency range of 2.25–2.76, 5.84–6.15 GHz, and 9.63–9.76 GHz, where maximum magnitude is achieved at 2.50 GHz, 6.02 GHz, and 9.70 GHz, respectively. This specific resonance frequency reached the highest 99.61 %, 98.03 %, and 98.79 % absorption, which covers the S, C, and X band frequency spectrum. Various electrical, magnetic, mechanical, and multi-parameter responses are examined to achieve almost perfect absorption (PA). The enormous range of possible uses of metamaterial, such as absorber wave modification, infrared imaging, radiative cooling, energy harvesting, and chemical detection, makes it appreciated. The CaCoAlFe2O4 ferrite-based flexible metamaterial absorber structure has ultra-thin, flexible, and non-corrosive advantages.

Theoretical prediction of perovskite ARH3 (A = K, Li, Rb; R[dbnd]Ca, Sr) hydride materials for hydrogen storage applications: A DFT investigation

Hydrogen (H2) storage has attracted the greatest attention in the contemporary day because of the shortage of fuel. The water splitting is considered less cost-effective and lead-free energy production by the photocatalytic process to produce hydrogen as a fuel for vehicles, petroleum refining, Pharmaceuticals, and glass purification. Perovskite materials play a vital role in H2 storage and production applications. The density functional theory (DFT) using the CASTEP code is used to study the various structural, electrical, optical, mechanical, and hydrogen (H2) capacity properties of ARH3 (A = K, Li, Rb; RSr, Ca) compounds. The compounds under investigations are optimized in the cubic structure; for ARH3 (A = K, Li, Rb; RSr, Ca), the optimized lattice constants are 3.924, 4.302, 4.559, 4.817, 4.647, and 4.884 Å, respectively. Since these hydrides are thermally stable, their formation energy is exhibited negative values. ARH3 may find usage in H2 storage applications due to its high gravimetric H2 storage densities (6.042 and 3.678 wt% for LiCaH3 and KCaH3, respectively). Furthermore, band gaps of 2.71, 2.38, 3.27, 2.73, 1.85, and 2.83 eV for ARH3 (A = K, Li, Rb; RCa, Sr) respectively, confirm the semiconductor behavior. These substances satisfy born stability criteria due to its mechanical parameters which derived from elastic constant values such as Pugh's ratio and modulus. Additionally, Pugh's ratio and Cauchy pressure demonstrate that, in contrast to other compounds, the KCaH3 compound has a ductile character (0.29). According to our analyses, studied compounds are observed a potential candidate for hydrogen storage devices.

The Role of Surfactant Head Group Charge on Binding of Hoechst 33258 with Micelles

AbstractOwing to the diverse biological application, photophysical behaviour of Hoechst 33258 (H33258) is an important topic in biophysical research. Here, we have reported the photophysical behavior of H33258 in model biomembrane mimicking micellar microenvironment. In order to understand the molecular mechanism of the interaction of H33258 with micelles, we have used cationic (Hexadecetyltrimethyl ammonium bromide (CTAB)), anionic (sodium dodecyl sulphate (SDS)), and non‐ionic (t‐octylphenoxypolyoxyethanol, Triton‐X100 (TX 100)) micelles. From the steady‐state emission study the evaluated apparent binding constant (Kb) values for the complex formation between H33258 and CTAB, SDS and TX 100 micelle were (1.45±0.42)×105, (31.95±4.89)×105 and (3.10±0.73)×105 M−1, respectively. Thus, it was found that the Kb value was greater in the case of anionic micelle than non‐ionic and cationic micelles. Such differences in Kb values were due to the electrostatic interaction and hydrogen bond formation between the probe molecule and micelles. In addition, time‐resolved fluorescence decay and time‐resolved fluorescence anisotropy studies were performed to understand the dynamical behavior of H33258 in presence of micelles. The interaction of H33258 with micelles might be useful to study the structure and dynamics of different bio‐membranes and to formulate new drug delivery system.

Performance Evaluation of Fractional Proportional–Integral–Derivative Controllers Tuned by Heuristic Algorithms for Nonlinear Interconnected Tanks

This article presents an in-depth analysis of three advanced strategies to tune fractional PID (FOPID) controllers for a nonlinear system of interconnected tanks, simulated using MATLAB. The study focuses on evaluating the performance characteristics of system responses controlled by FOPID controllers tuned through three heuristic algorithms: Ant Colony Optimization (ACO), Grey Wolf Optimizer (GWO), and Flower Pollination Algorithm (FPA). Each algorithm aims to minimize its respective cost function using various performance metrics. The nonlinear model was linearized around an equilibrium point using Taylor Series expansion and Laplace transforms to facilitate control. The FPA algorithm performed better with the lowest Integral Square Error (ISE) criterion value (297.83) and faster convergence in constant values and fractional orders. This comprehensive evaluation underscores the importance of selecting the appropriate tuning strategy and performance index, demonstrating that the FPA provides the most efficient and robust tuning for FOPID controllers in nonlinear systems. The results highlight the efficacy of meta-heuristic algorithms in optimizing complex control systems, providing valuable insights for future research and practical applications, thereby contributing to the advancement of control systems engineering.

Influence of Illumination Spectrum on Dissociation Kinetics of Iron–Boron Pairs in Silicon

Photodissociation kinetics of iron–boron (FeB) pairs in boron‐doped Czochralski silicon is studied experimentally using different light sources. It is shown that the FeB dissociation rate depends not only on integrated light intensity and overall carrier generation rate, but also on spectral composition of illumination. The value of the material constant of dissociation K varies and has been determined to be within s. The investigation reveals an increase in the dissociation rate with increase in photon energy. The results indicate that recombination‐enhanced defect reaction is the primary factor in the second stage of pair dissociation.

Binding and displacement study of gentamicin, 5-fluorouracil, oxytetracycline and rolitetracycline with (BSA: Drug2) complex using spectroscopic and calorimetric techniques: Biophysical approach

Understanding of energetics of interactions between drug and protein is essential in pharmacokinetics and pharmacodynamics study. The binding affinity (K) helps in investigating how tightly or loosely drug is bound to protein. The binding, displacement, conformational change and stability study of drugs- gentamicin (GM), 5-fluorouracil (5FU), oxytetracycline (OTC) and rolitetracycline (RTC) with bovine serum albumin (BSA) has been carried out in presence of each other drug by fluorescence, UV–visible spectroscopy, molecular docking, circular dichroism techniques and thermal denaturation method. The site marker study and docking methods have confirmed that 5FU and GM are able to bind at site 1 and OTC and RTC at site II of BSA. The order of their binding affinities with BSA for the binary system were as GM <5FU < OTC < RTC with the order of 102 < 103 < 105 < 105–6 M−1. The displacement study has shown that higher affinity drug decreases the equilibrium constant of another drug already in bound state with BSA if both these drugs are having the same binding site. Therefore 5FU, GM (binding site 1) drugs were not able to displace OTC and RTC (binding site 2) and vice-versa as they are binding at two different sites. The binding constant values were found to be decreasing with increasing temperature for all the systems involved which suggests static or mixed type of quenching, however can only confirmed with the help of TCSPC technique. The ΔG0 (binding energy) obtained from docking method were in accordance with the ITC method. From molecular docking we have determined the amino acid residues involved in binding process for binary and ternary systems by considering first rank minimum binding energy confirmation. From CD it has been observed that RTC causes most conformational change in secondary and tertiary structure of BSA due to the presence of pyrrole ring. OTC-RTC with higher affinity showed highest melting temperature Tm values while low affinity drugs in (5FU-GM) combination showed lowest Tm value. 5FU showed large endothermic denaturation enthalpy ΔHd0 due to the presence of highly electronegative fluorine atom in the pyridine analogue.

An Analytical Model for Cosmology with a Single Input, the Redshift

We propose an analytical model for cosmology which requires only one parameter as an input. This parameter is the redshift. The model is based on conservation of energy, Planck’s Radiation Law, and the relation between energy and frequency of waves. The model yields the current age of the universe, the age of the universe at the CMB emission, as well as the time histories of its expansion velocity and acceleration. The model also is used to show the existence of a constant energy per unit area, associated with the momentum energy of photons, which generates the pressure that perpetuates the expansion of the universe. The model is completely independent of the ɅCDM model but implicitly includes the effects of gravity. Using the model we show the existence of a constant in nature that under certain assumptions can represent the Hubble constant. We have used the model to derive the Hubble constants measured by Reiss et al. and by the Planck Collaboration. Using the model we show that the path of light in the Planck collaboration measurement is along a circular arc, while the Reiss et al. measurement path is exactly along the chord of the same circular arc. The difference in the light travel times along these two paths matches exactly the difference between the two measured values for the Hubble constant, as measured by Reiss et al. and as measured by the Planck Collaboration. This result explains the cause of tension between the two methods of measurement.

Chemosensitive Properties of Electrochemically Synthesized Poly-3-Thienylboronic Acid: Conductometric Detection of Glucose and Other Diol-Containing Compounds under Electrical Affinity Control.

Due to the presence of the boronic acid moieties, poly-3-thienylboronic acid has an affinity for saccharides and other diol-containing compounds. Thin films of this novel chemosensitive polymer were synthesized electrochemically on the gold surface. The adhesion of the polymer was enhanced by the deposition of a monomolecular layer of thiophenol. The technology was used to fabricate conductometric sensors for glucose and other diol-containing compounds. Simultaneous two- and four-electrode conductivity measurements were performed. The chemical sensitivity to sorbitol, fructose, glucose, and ethylene glycol was studied at different pH and electrode potentials, and the corresponding binding constants were obtained. Depending on the electrode potential, the reciprocal values of the binding constants of glucose to poly-3-thienylboronic acid at neutral pH are in the range of 0.2 mM-1.0 mM. The affinity for glucose has been studied in buffer solutions and in solutions containing the major components of human blood. It was shown that the presence of human serum albumin increases the affinity of poly-3-thienylboronic acid for diol-containing compounds.

Can Hubble tension be eased by invoking a finite range for gravity?

The estimation of the Hubble constant in the past few decades has increasingly become more accurate with the advancement of new techniques. However, its value seems to depend on the epoch at which the measurements are made. The Planck estimate of the Hubble constant from the observations of the cosmic microwave background radiation in the early universe is about [Formula: see text], whereas that obtained from the distance indicators at the current epoch is [Formula: see text]. This discrepancy between the two groups of measurement is termed as the Hubble tension which has gained much attention in the past few decades with growing significance as measurements from both, the early and the late universe, studies continue to produce results with increasing precision. In this work, we propose a modification to gravity by considering a finite range gravitational field as an alternate explanation for this discrepancy in the value of the Hubble constant.

Experimental and molecular modelling demonstration of effective DNA and protein binding as well as anticancer potential of two mononuclear Cu(II) and Co(II) complexes with isothiocyanate and azide as anionic residues

In the present study, one mononuclear Cu(II) [CuL(SCN)] (1) and one mononuclear Co(II) [CoLN3] (2) complexes, with a Schiff base ligand (HL) formed by condensation of 2-picolylamine and salicylaldehyde, have been successfully developed and structurally characterized. The square planer geometry of both complexes is fulfilled by the coordination of one deprotonated ligand and one ancillary ligand SCN−(1) or N3−(2) to the metal centre. Binding affinities of both complexes with deoxyribonucleic acid (DNA) and human serum albumin (HSA) are investigated using several biophysical and spectroscopic techniques. High values of the macromolecule-complex binding constants and other results confirm the effectiveness of both complexes towards binding with DNA and HSA. The determined values of the thermodynamic parameters support spontaneous interactions of both complexes with HSA, while fluorescence displacement and DNA melting studies establish groove-binding interactions with DNA for both complexes 1 and 2. The molecular modelling study validates the experimental findings. Both complexes are subjected to an MTT test establishing the anticancer property of complex 1 with lower risk to normal cells, confirmed by the IC50 values of the complex for HeLa cancer cells and HEK normal cells. Finally, a nuclear staining analysis reveals that the complexes have caused apoptotic cell death.

Multi-spectral and docking assessments to explore the combination of an antiviral drug, entecavir with bovine serum albumin

Molecular interaction of entecavir (ETV) with the transport protein, albumin from bovine serum (BSA) was explored through multispectral and molecular docking approaches. The BSA fluorescence was appreciably quenched upon ETV binding and the quenching nature was static. The ETV–BSA complexation and the static quenching process were further reiterated using UV–visible absorption spectra. The binding constant (Ka) values of the complex were found as 1.47 × 104–4.0 × 103 M−1, which depicting a modarate binding strength in the ETV–BSA complexation. The experimental outcomes verified that the stable complexation was primarily influenced by hydrophobic interactions, hydrogen bonds and van der Waals forces. Synchronous and 3-D fluorescence spectral results demonstrated that ETV had significant impact on the hydrophobicity and polarity of the molecular environment near Tyr and Trp residues. Competitive site-markers displacement (with warfarin and ketoprofen) results discovered the suitable binding locus of ETV at site I in BSA. The molecular docking assessments also revealed that ETV formed hydrogen bonds and hydrophobic interactions with BSA, predominantly binding to site I (sub-domain IIA) of BSA.

Determination of ionization/protonation constant values of some guanine derivative drugs by traditional/ green RPLC and UV–Vis spectrophotometric methods

In this study, the greenreverse-phase liquid chromatography (RPLC) method was used in addition to the traditional RPLC method to determine the ionization/protonation constants (pKa) of the guanine derivatives ganciclovir, valacyclovir, and valganciclovir. The determination of these values was carried out in binary acetonitrile–water mixtures (for the traditional RPLC method), ethanol–water binary mixtures (for the green RPLC method), and in aqueous solution of a micelle-forming surfactant (for pure micellar chromatography). The pKa values sspKa of the compounds were calculated using the linear solvation energy relationship (LSER) method in the studied hydro-organic and micellar solvent-free mixtures. Moreover, the UV–Vis spectrophotometric method was used to compare the sspKa values of ganciclovir, valaciclovir, and valganciclovir obtained in a acetonitrile–water medium using another method. The pKa values ​​of the examined compounds in water were calculated using the linear relationship between the sspKa values ​​determined in hydroorganic mixtures and some macroscopic values ​​of acetonitrile and ethanol. Additionally, wwpKa values ​​were determined in the micellar solvent-free mobile phase. Subsequently, the wwpKa values calculated by these direct and indirect methods were compared and the agreement between them was excellent. By using the wwpKa value calculated for each compound, the ionization percentages were calculated at different pH (1–12) values with the Henderson-Hasselbalch equation. The environmental impact of the RPLC methods used in this study was assessed using the green metrics tools GAPI and AGREE. The result of the investigation was that the environmental suitability of the green methods is satisfactory.

Theoretical and experimental demonstration of mononuclear Ni(II) and dinuclear Ni(III) complexes concerning their catalytic activity, DNA/ protein binding efficacy

The successful use of metal complexes in enzyme catalysis and biomedical applications boosts researchers to develop more and more metal-based compounds to inspect their said applications.In the present work one novel mononuclear Ni(II) [Ni(L1)2] (1) and one di nuclear Ni(III) complexes [Ni(L2)2(N3)2] (2) have been developed by utilizing N2O donor Schiff base ligand HL1 and N2O2 donor Schiff base ligand H2L2 respectively. The single crystal data analysis reveals that in complex 1 two deprotonated ligands coordinate to the Ni(II) forming a distorted octahedral geometry. The asymmetric unit of complex 2 comprises one deprotonated ligand (both the protons of phenolic –OH group were deprotonated), one azide anion, and one Ni(III). Two Ni(III) centers are connected via phenoxide bridging. Followed by the structural analysis the UV spectroscopic study is performed to understand the catecholase-like activity of the developed complexes by using 3,5-di-tertbutyl catechol (3,5-DTBC). The calculated turnover numbers (Kcat) for both complexes disclose the fact that complex2 is more susceptible to this catalytic process than 1. During the catalysis process, the production of Ni(II) in the case of complex2is favorable and this is the main factor to show its higher susceptibilitytowards the catalytic process. The biomedical applicability in terms of anticancer and antibacterial of complexes 1 and 2 is assessed by evaluating their interaction ability with DNA and HSA with the help of several spectroscopic approaches. The remarkably high complex-macromolecules binding constant values, obtained from electronic titration approve the binding efficacy of the target complexes (order ∼ 105). But if a tiny comparison is done then it is seen that complex 2 shows better DNA and HSA binding efficacy. The theoretical approach using molecular docking study fully validates the experimental findings.

Predicting decomposition temperatures and carbonization feasibility of heterocycles with their decomposition mechanism

Pyrolysis of heterocyclic compounds such as Meldrum’s acid (MA) derivatives has been studied with focus on two key mechanisms analysing their energy barrier diagrams using the hybrid density functional theory method M06-2X. The feasibility of these decomposition reactions was calculated specifically for MA, monomethyl Meldrum’s acid (MMA), dimethyl Meldrum’s acid (DMMA), methylene Meldrum’s acid (MeMA) and (dimethylamino)methylene Meldrum’s acid (DMAMeMA), based on previous experimental analysis. The barrier to initial decomposition products (ketene or substituted ketenes with CO2 and acetone) were found to be endothermic requiring activation energies (∼180 – 230 kJ/mol) at decomposition temperatures of 280, 299, 301, 503 and 414 K respectively. Transition state theory calculations show MeMA and DMAMeMA are thermally more stable than other derivatives with low values for the rate constants and high energy barriers to produce initial decomposition products, suggesting they can produce fine carbon materials during carbonization. DMMA is found the best option for obtaining heteroatoms-doped carbon material formation.

A Female-Biased Chemosensory Protein PxutCSP19 in the Antennae of Papilio xuthus Tuned to Host Volatiles and Insecticides.

Chemosensory protein (CSP) genes significantly enriched in the female antennae are potential molecular candidates for mediating female oviposition behaviors. In this study, we presented the interaction mechanisms of a female-antenna-biased PxutCSP19 in Papilio xuthus to 47 host volatiles, four biopesticides and 24 synthetic insecticides. Using a bioinformatics-based homology search, 22 genes orthologous to PxutCSP19 were identified from 22 other Papilio butterflies with high sequence identities to each other (73.20~98.72%). Multiple alignment analyses revealed a particularly extended N-terminus of Papilio CSP19s (an average of 154 residues) compared to insects' typical CSPs (approximately 120 residues). The expression profiles indicated that PxutCSP19 was significantly enriched in the female antennae, with a 31.81-fold difference relative to the male antennae. In ligand-binding assays, PxutCSP19 could strongly bind six host odorants with high affinities, ranging from dissociation constant (Ki) values of 20.44 ± 0.64 μM to 22.71 ± 0.73 μM. Notably, this protein was tuned to a monoterpenoid alcohol, linalool, which generally existed in the Rutaceae plants and elicited electrophysiological and behavioral activities of the swallowtail butterfly. On the other hand, PxutCSP19 was also capable of binding eight insecticides with stronger binding abilities (Ki < 12 μM) compared to host odorants. When an extended N-terminal region of PxutCSP19 was truncated into two different proteins, they did not significantly affect the binding of PxutCSP19 to ligands with high affinities, suggesting that this extended N-terminal sequences were not involved in the specificity of ligand recognition. Altogether, our study sheds light on the putative roles of PxutCSP19 enriched in the female antennae of P. xuthus in the perception of host volatiles and the sequestering of insecticides, and it complements the knowledge of butterfly CSPs in olfaction and insecticide resistance.

Intrinsic and extrinsic relaxation mechanisms for controlling spin current intensity in Fe 100−x Co x /Ta bilayers

Controlling the damping parameter in metallic ferromagnetic thin films is a key step for spintronic applications in which spin currents are generated by spin pumping. The coexistence of two states with low and high damping constant values would allow to obtain states of high and low spin current intensity, respectively. We have fabricated Fe 100−x Co x /Ta (with nominal x = 0, 15, 20, 25, 30 and 35) bilayers in which the Fe 100−x Co x layers grow epitaxially and the Ta layer is polycrystalline. We have found the coexistence of Gilbert damping and two magnon scattering mechanisms linked to a sign change in the magnetocrystalline anisotropy constant that allows the manipulation of low and high intensity states of the measured inverse spin Hall effect voltage. Bilayers with lower Co concentrations ( x⩽ 25%) present different relaxation mechanisms (isotropic Gilbert damping and two magnon scattering) and an extra ferromagnetic resonance linewidth broadening produced due to mosaicity. Bilayers with Co concentration x> 25% present a dominating Gilbert damping for all directions in the film plane. However, in this concentration range the damping constant is anisotropic and when the magnetic field is applied along the hard magnetization direction α increases ∼420% with respect to the value obtained for the easy magnetization direction. Coexistence of isotropic Gilbert damping and two magnon scattering generated spin currents 2.5 times larger when the field is applied along the hard magnetization axis compared to the value observed in the easy magnetization axis. Thesefindings make the Fe 100−x Co x /Ta system an excellent candidate for spintronic device applications.

Trimethyltin(IV) (p-fluoro-/p‑hydroxy-/p-nitro-)benzoates and their benzimidazole complexes: X-ray structures of [Me3Sn(p-NO2C6H4CO2)]n, and [Me3Sn(p-NO2C6H4CO2). bz], DFT calculations, DNA binding, and DNA cleavage studies

A series of trimethyltin(IV) carboxylates with Sn‒O bonds: [Me3Sn(p-FC6H4CO2)] (1), [Me3Sn(p-HOC6H4CO2)] (2), [Me3Sn(p-NO2C6H4CO2)]n (3), and their benzimidazole complexes with Sn‒N bond: [Me3Sn(p-FC6H4CO2).bz] (4), [Me3Sn(p-HOC6H4CO2).bz] (5), and [Me3Sn(p-NO2C6H4CO2).bz] (6) (bz = benzimidazole) have been synthesized and characterized by elemental analysis, FT-IR, 1H, 13C, 119Sn NMR, and electrospray ionization mass spectrometric (ESI-MS) studies. The crystal structures for (3) and (6) have been authenticated by X-ray diffraction. In the crystal structure, polymeric coordination compound (3) and the monocrystal system (6) have trigonal bipyramidal geometry around the Sn centre, where most electronegative atoms occupied the axial positions, and three methyl groups occupied the equatorial positions. The gas-phase tetrahedral geometries of (1) and (2), asymmetric unit (Sc-XRD) of (3), and trigonal bipyramidal geometries of (4–6) have been optimized using the B3LYP function and LanL2Z basis, and obtained ∠C-Sn-C bond angles agree with those obtained from NMR/X-ray studies. The interaction of (1–6) with calf thymus DNA (ctDNA) has been investigated by spectroscopic titrations such as UV–visible, fluorescence, and circular dichroism (CD) titrations, and calculated binding constant values found in the 104–105 M−1 range which suggest a groove binding or electrostatic interaction between complexes and ctDNA. The gel electrophoresis studies suggest that (1–6) effectively cleaved the plasmid pBR322 DNA into three bands: the supercoiled, nicked/circular, and linear structures. The intriguing biophysical findings from the study indicate that these complexes have properties that make them strong contenders for additional research as potential anti-cancer agents.

Dependency of the drag coefficient on boundary layer stability beneath drifting sea ice in the central Arctic Ocean

The ice-ocean drag coefficient Cw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{w}$$\\end{document} and turning angle θw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ heta_{w}$$\\end{document} are crucial parameters in ice-ocean coupled simulations, determining the transfer of momentum between the two media. These parameters are often treated as constants regardless of the static stability at the ice-ocean interface. This study investigates the variability of Cw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{w}$$\\end{document} and θw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ heta_{w}$$\\end{document} based on direct observations of thermal and kinetic energy balance. The observations were conducted beneath multiyear ice packs widely across the central Arctic during a period transitioning from ablation to refreezing, indicating significant variability of Cw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{w}$$\\end{document} = 1–130 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 10−3 and θw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ heta_{w}$$\\end{document} = − 19–1° at 5 m depth. Comparing different stations, the observations suggest a pronounced dependence of Cw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{w}$$\\end{document} on the stability parameter (μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}) resulting from mechanical and buoyant forcing. Cw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{w}$$\\end{document} rapidly decays with increasing μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}, indicating that the ice-to-ocean momentum transfer is enhanced for neutral or unstable conditions, while it is weakened for stable conditions. In addition, observed vertical profiles of currents revealed that |θw|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\ heta_{w}|$$\\end{document} tends to be smaller for unstable and larger for stable conditions. We suggest that numerical simulations using constant values could result in an underestimate of large-scale near-surface currents during the ice growing period.

Photocatalytic activity of Ho3+-Yb3+ activated BiVO4 upconverting phosphors

The BiVO4:Ho3+-Yb3+ upconverting phosphors have been synthesized by using the chemical co-precipitation method and optimized with 0.7 % Ho3+ + 6 % Yb3+ combination through frequency upconversion emission study. The synthesized phosphors have been characterized through XRD (X-Ray diffraction), FESEM (Field emission scanning electron microscopy), HR-TEM (High resolution- Transmission electron microscopy), UV–vis diffuse reflectance spectroscopy (DRS), Raman, and FT-IR (Fourier transform infrared spectroscopy). The XPS (X-ray photoelectron spectroscopy) analysis has been performed to study the elemental composition, chemical, and electronic states of the atoms present in the optimized sample. The specific surface area of the pure and optimized phosphors has been determined through BET (Brunauer-Emmett-Teller) analysis. From the XRD analysis, it is clear that on doping, the crystal structure of BiVO4 changes from monoclinic to tetragonal structure. The values of rate constants for the photocatalytic performance of the upconverting codoped and pure BiVO4 phosphors under the illumination with an artificial solar lamp for degradation of MB dye are found to be 0.00498 min−1 and 0.00269 min−1, respectively. To verify these results, the same experiment has also been performed under the visible LED (Light-emitting diode) light illumination. This enhancement of ∼ 85 % in the rate constant of the photocatalytic performance ensured the utilization of the NIR portion of the light by the codoped BiVO4 phosphors through the frequency upconversion process. The material’s recycling photocatalysis experiment for three cycles has been performed to check its reusability. The upconversion emission and XRD analysis of the materials after photocatalysis have been performed. From this study, it is confirmed that the stability of the sample is better even after three cycles of photocatalytic dye degradation experiment.