Electronic and optical properties of quaternary selenides for optoelectronic applications: Insights from DFT+U-computations

The optical properties, electronic charge density, electronic structure of the new layered selenides materials, BaGdCuSe₃, CsUCuSe₃, CsZrCuSe₃, and CsGdZnSe₃ compounds have been calculated by using the full potential and linear augmented plane wave (FP-LAPW) methods as applied in the WIEN2k package, which is based on the density functional theory. The ALnMSe3 compound's structure of these was (A = Cs, Ba; Ln = Zr, Gd, U; M = Cu, Zn) is composed of (n = 1, 2) layers, which might be separated by A atoms. It is to be observed that there is strong hybridization between the s, p, and d states of Zr, Gd, and Cu atoms. Around the gadolinium atom, the charge density contours are completely circular, but the Gadolinium “Gd” atom shows an ionic nature. To calculate the refractive index, we used Kramer's Kronig correlations with the imaginary part dielectric function. The decrease in the refractive index is due to the lack of probability for direct excitation of the electrons, resulting in a loss of energy. The value of the static refractive index for all reference compounds is about 1.75–2.25, which is indication that the material used in optoelectronic devices.     

The utility of ultra-performance liquid chromatography/electrospray ionisation time-of-flight mass spectrometry for multi-residue determination of pesticides in strawberry

The utility of ultra-performance liquid chromatography/orthogonal-acceleration time-of flight mass spectrometry (UPLC/TOFMS) for the rapid qualitative and quantitative analysis of 100 pesticides targeted in strawberry was assessed by comparing results with those obtained using a validated in-house UPLC tandem mass spectrometry (MS/MS) multi-residue method. Crude extracts from retail strawberry samples received as part of the 2007 annual UK pesticide residues in food surveillance programme were screened for the presence of pesticide residues using UPLC/TOFMS. Accurate mass measurement of positive and negative ions allowed their extraction following 'full mass range data acquisition' with negligible interference from background or co-eluting species observed during UPLC gradient separation (in a cycle time of just 6.5 min per run). Extracted ion data was used to construct calibration curves and to detect and identify any incurred residues (i.e. pesticides incorporated in or on the test material following application during cultivation, harvest and storage). Calibration using matrix-matched standards was performed over a narrow concentration range of 0.005-0.04 mg kg(-1) with determination coefficients (r2) > or =0.99 for all analytes with the exception of malathion/fenarimol/fludioxanil (r2 = 0.98), quassia/pymetrazine (r2 = 0.97) and fenthion sulfone (r2 = 0.95). Residues found in selected samples ranged from 0.025-0.28 mg kg(-1) and were in excellent agreement with results obtained using UPLC/MS/MS. Mass measurement accuracies of < or =5 ppm were achieved consistently throughout the separation, mass range and concentration range of interest thus providing the opportunity to obtain discrete elemental compositions of target ions.     

3D Printable Geopolymer Composites Reinforced with Carbon-Based Nanomaterials – A Review

Three-dimensional (3D) geopolymer printing (3DGP) technology is a rapidly evolving digital fabrication method used in the construction industry. This technology offers significant benefits over 3D concrete printing in terms of energy saving and reduced carbon emissions, thus promoting sustainability. 3DGP technology is still evolving, and researchers are striving to develop high-performance printable materials and different methods to improve its robustness and efficiency. Carbon-based nanomaterials (CBNs) with beneficial properties have a wide range of applications in various fields, including as concrete/geopolymer systems in construction. This paper comprehensively reviews the research progress on carbon-based nanomaterials (CBNs) used to develop extrusion-based 3D geopolymer printing (3DGP) technology, including dispersion techniques, mixing methods, and the materials′ performance. The rheological, mechanical, durability, and other characteristics of these materials are also examined. Furthermore, the existing research limitations and the prospects of using 3DGP technology to produce high-quality composite mixtures are critically evaluated.     

On topological properties of poly honeycomb networks

Topological indices are numerical parameters of a graph which characterize its topology and are usually graph invariant. In QSAR/QSPR study, physico-chemical properties and topological indices such as the Randi?, the atom-bond connectivity (ABC) and the geometric-arithmetic (GA) indices are used to predict the bioactivity of chemical compounds. Graph theory has found a considerable use in this area of research. In this paper, we study poly honeycomb networks which are generated by a honeycomb network of dimension n and derive analytical closed results for the general Randi? index \(R_\alpha (G)\) for different values of \(\alpha \), for a David derived network \((\textit{DD}(n))\) of dimension n, a dominating David derived network \((\textit{DDD}(n))\) of dimension n as well as a regular triangulene silicate network of dimension n. We also compute the general first Zagreb, ABC, GA, \(\textit{ABC}_4\) and \(\textit{GA}_5\) indices for these poly honeycomb networks for the first time and give closed formulas of these degree based indices in case of poly honeycomb networks.     

Triaxial superdeformation in Lu

High-spin states in ¹⁶³Lu have been investigated using the Euroball spectrometer array. The previously known superdeformed band has been extended at low and high energies, and its connection to the normal-deformed states has been established. From its decay the mixing amplitude and interaction strength between superdeformed and normal states are derived. In addition, a new band with a similar dynamic moment of inertia has been found. The experimental results are compared to cranking calculations which suggest that the superdeformed bands in this mass region correspond to shapes with a pronounced triaxiality (γ≈±20°).     

Lyciumaside and Lyciumate: A New Diacylglycoside and Sesquiterpene Lactone from Lycium shawii

One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (¹H‐ and ¹³C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC₅₀ = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays.     

Tailoring the optical and magnetic properties of La-BaM hexaferrites by Ni substitution

We investigate the impact of Ni insertion on the structural,optical,and magnetic properties of Ba_0.8La_0.2Fe_12-xNi_xO₁₉hexaferrites(Ni substituted La-BaM hexaferrites).Samples were prepared using the conventional co-precipitation method and sintered at 1000℃for 4 hours to assist the crystallization process.An analysis of the structure of the samples was carried out using an x-ray diffraction(XRD)spectrometer.The M-type hexagonal structure of all the samples was confirmed using XRD spectra.The lattice parameters a and c were found to be in the ranges of 5.8925±0.001 nm–5.8952±0.001 nm and 23.2123±0.001 nm–23.2219±0.001 nm,respectively.The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra,respectively.EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio.A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm–1100 nm.The optical energy bandgap of the samples was found to be in the range of 1.21 eV–3.39 eV.The M–H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe–60 kOe.A high saturation magnetization of 99.92 emu/g was recorded in the sample with x=0 at a microwave operating frequency of 22.2 GHz.This high value of saturation magnetization is due to the substitution of La3+ions at the spin-up(12k,2a,and 2b)sites.The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites.Therefore,we suggest that the prepared samples are suitable for use in magneto-optic applications.     

High-spin states in the 96Tc nucleus

High-spin states in the ⁹⁶Tc nucleus have been studied with the reactions ⁸²Se(¹⁹F,5nγ) at 68 MeV and Zn(³⁶S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10 MeV and spin 21-22?. Received: 19 January 2001 / Accepted: 30 March 2001