Designing spirobifullerene core based three-dimensional cross shape acceptor materials with promising photovoltaic properties for high-efficiency organic solar cells

The development of organic electron acceptor materials is one of the key factors for realizing high-performance organic solar cells (OSCs). Nonfullerene electron acceptors, compared to traditional fullerene acceptor materials, have gained much impetus owing to their better optoelectronic tunabilities and lower cost, as well as higher stability. Therefore, 5 three-dimensional (3D) cross-shaped acceptor materials having a spirobifullerene core flanked with 2,1,3-benzothiadiazole are designed from a recently synthesized highly efficient acceptor molecule SF(BR) ₄ and are investigated in detail with regard to their use as acceptor molecules in OSCs. The density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed for the estimation of frontier molecular orbital (FMO) analysis, density of states analysis, reorganization energies of electron and hole, dipole moment, open-circuit voltage, photo-physical characteristics, and transition density matrix analysis. In addition, the structure-property relationship is studied, and the influence of end-capped acceptor modifications on photovoltaic, photo-physical, and electronic properties of newly selected molecules ( H1-H5 ) is calculated and compared with reference ( R ) acceptor molecule SF(BR) ₄ . The structural tailoring at terminals was found to effectively tune the FMO band gap, energy levels, absorption spectra, open-circuit voltage, reorganization energy, and binding energy value in selected molecules H1 to H5 . The 3D cross-shaped molecules H1 to H5 suppress the intermolecular aggregation in PTB7-Th blend, which leads to high efficiency of acceptor material H1 to H5 in OSCs. Consequently, better optoelectronic properties are achieved from designed molecules H1 to H5 . It is proposed that the conceptualized molecules are superior than highly efficient spirobifullerene core-based SF(BR) ₄ acceptor molecules and, thus, are recommended to experiments for future developments of highly efficient solar cells.     

New design strategy for the two-photon active material based on push-pull substituted bisanthene molecule

In the present work, we have critically examined the origin of strong two-photon transition probability of a donor-acceptor substituted bisanthene molecule that imitates a small piece of edge passivated (4, 4) graphene nanoribbon. In our calculations, we have considered -OMe, and -NH(2) as donors and -NO(2) as an acceptor. The one- and two-photon absorption parameters are evaluated using state-of-the-art linear and quadratic response theory, respectively, and all these calculations are carried out within the framework of time dependent density functional theory. To give a proper judgment on our findings, we have used the long-range corrected CAMB3LYP functional for all of the time dependent calculations. The present investigation reveals that the bisanthene molecule with three pairs of donor/acceptor moiety has a lower two-photon transition probability than that of a suitably designed bisanthene with only a single pair of donor/acceptor moiety. This in silico observation is consistent for all of the donor/acceptor moieties chosen in the present work. A comprehensive analysis at the two state model level of theory clearly offers us a verdict that by placing the donor/acceptor moiety in a suitable position of bisanthene, we can create a significant asymmetry in the electron density in the first excited state, which eventually leads to a significant difference in the ground and excited state dipole moment and is attributed to the higher two-photon transition probability of a particular bisanthene with a single pair of donor/acceptor moiety than bisanthene with three pairs of donor/acceptor.     

Magnetic characteristics of HPT deformed soft-magnetic materials

Five sets of soft-magnetic metals, such as pure Fe, pure Ni, Fe-3 wt% Si, Fe-6.5 wt% Si and Fe-17 wt% Co, were subjected to high pressure torsion (HPT) up to strain levels where a saturation of the microstructural refinement is observed. Following HPT at 77, 293 and 723 K, transmission electron microscopy (TEM) was used to study the grain size and grain shape of the severely deformed metals. The coercivity H_C was characterized in a magnetic closed system by using ring shaped samples. Magnetic measurements obtained on ring shaped samples give a much higher accuracy for determining the coercivity. Depending on the material the mean microstructural sizes in the steady state vary from 300 nm at 723 K to 30 nm at 77 K, respectively. The coercivity of the deformed materials first increases with decrease in grain size. Once the crystallite size is far below 100 nm the coercivity shows a strong decrease.     

Determination of tryptophan in raw materials, rat brain and human plasma by RP-HPLC technique

This paper describes tryptophan (TRP) estimation in raw human plasma and rat brain by reversed-phase high-performance liquid chromatography (RP-HPLC). Estimation was carried out on a Purospher STAR C18 column using water-acetonitrile (90:10 v/v, at pH 2.7) mixture at a rate of 1.5 mL/min as mobile phase. Eluents were monitored at 273 nm by an ultraviolet detector. The method was linear (R(2) > 0.999), precise (intra-day and inter-day precision <2%) in the range of 0.25-20 μg/mL. The detection and quantification limits were 0.0144 μg/mL and 0.0437 μg/mL, respectively. In human plasma, Day 1 and Day 2 precision were 0.054-2.29% and 1.66-3.7%; whereas precisions in rat brain were 1.23-2.3% and 0.677-4.2%, respectively. The method was applied to study TRP level in human smokers and in arthritic rat brain. An efficient RP-HPLC method was developed for TRP determination that worked for clinical and research purposes.     

Synthesis of isoamyl acetate usin NaX and NaY zeolites as catalysts

A liquid phase esterification reaction between glacial acetic acid and isoamyl alcohol has been studied using NaX and NaY zeolites as catalysts. The influence of calcination temperature, the amount of catalysts, reaction temperature, time of esterification and the molar ratio of the reactants has been investigated. Water insoluble products have been isolated from the reaction mixture and analyzed for the ester. Both NaX and NaY are found to be active as catalysts in the reaction. However, their catalytic activity varies with the reaction conditions and their calcination temperature. The reaction has been found to be 100% selective to ester formation. Catalytic activity of the zeolites has been correlated with their surface acidity.     

Development and Validation of a Liquid Chromatographic Method for the Determination of Leflunomide: Application to in vitro Drug Metal Interactions

Leflunomide is a leading drug for the treatment of rheumatoid arthritis. The principle aim of this study was to develop and validate an RP‐HPLC method for the determination of leflunomide in bulk and pharmaceutical dosage form using diclofenac sodium as an internal standard. For this purpose, chromatography was accomplished on a Purospher Start, C₁₈ (5 (m, 12.5 cm×0.46 cm) column at ambient temperature. Methanol:water (80:20, V/V) solvent system was selected as mobile phase, the pH of which was adjusted to 3.4 by ortho‐phosphoric acid and delivered at a flow rate of 1.2 mL·min⁻¹. Seperation of leflunomide and diclofenac sodium was carried out on a Purospher Start, C₁₈ equipped with a UV‐visible detector at 248 nm. The suitability of the method for the quantitative determination of the drugs is proven by validation in accordance with the requirements laid down by the International Conference on Harmonization (ICH) guidelines. The method was accurate (99.55%–100.03%), specific, linear (R²>0.999) and precise (intra‐day precision 0.023%–0.93% and inter‐day precision 0.26%–0.944%) in the range of 0.5–20 (g·mL⁻¹. The minimum limit of detection and quantification in pharmaceutical formulation were 0.05 and 0.15 (g·mL⁻¹, respectively. Thus the proposed method is simple, accurate, reproducible and suitable for the routine analysis of leflunomide in pharmaceutical formulations and was applied to study in vitro drug‐metal interactions.     

Electrically Controlled Eight‐Spin‐Qubit Entangled‐State Generation in a Molecular Break Junction

The generation of spin‐based multi‐qubit entangled states in the presence of an electric field is one of the most challenging tasks in current quantum‐computing research. Such examples are still elusive. By using non‐equilibrium Green′s function‐based quantum‐transport calculations in combination with non‐collinear spin density functional theory, we report that an eight‐spin‐qubit entangled state can be generated with the high‐spin state of a dinuclear Fe(II) complex when the system is placed in a molecular break junction. The possible gate operation scheme, gating time, and decoherence issues have been carefully addressed. Furthermore, our calculations reveal that the preservation of the high spin state of this complex is possible if the experimentalists keep the electric‐field strength below 0.78 V nm^?1. In brief, the present study offers a unique way to realize the first example of a multi‐qubit entangled state by electrical means only.     

Synthesis of silver nanoparticles using root extract of Duchesnea indica and assessment of its biological activities

Treatment of microbial infections and inflammatory conditions have many challenges in terms of efficacy and safety issues. Novel approaches such as nanoparticles based drug delivery system have shown promising results to solve some of these problems. The aim of this study was to exploit the efficacy of the synthesized silver nanoparticles. In this study, silver nanoparticles (AgNPs) were biosynthesized using root extract (aqueous) of Duchesnea indica. They were characterized using different techniques such as, ultraviolet–visible (UV–Vis) spectrophotometry, transmission and scanning electron microscopy (TEM and SEM), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), fourier-transform infrared spectroscopy (FTIR) and zetasizer. The UV–Vis spectra gave a characteristic peak at 423 nm; XRD confirmed its crystalline structure; FTIR confirmed the involvement of phytochemicals in their capping and reduction; TEM images confirmed their spherical shape with average width of 20.49 nm and average area of 319.25 nm². Various biological activities were performed on these NPs, such as antimicrobial, anti-inflammatory, analgesic and muscle relaxant, which showed significant results as follow. Among bacterial strains, Salmonella typhi (MIC: 0.01 mg/ml) and Escherichia coli (MIC: 0.01 mg/ml), while among that of fungal Microsporum canis (MIC: 0.53 mg/ml) and Alternaria alternata (MIC: 0.51 mg/ml) were most susceptible. The AgNPs showed maximum anti-inflammatory activity (46.15 and 56.85%) at 20 mg/kg after 3 and 5 h of drug administration, comparable to that of standard. In-vivo model exhibited concentration dependent inhibition of both COX-2 and 5-LOX enzymes. Similarly, it exhibited maximum analgesic activity (54.24%) at 20 mg/kg dose after 60 min. of pain induction. Furthermore, they depicted maximum muscle relaxation (P < 0.01) after 60 and 90 min of drug administration. Above results suggest that these AgNPs can be studied further for the development of more effective and safe formulations.     

Comparison of radii sets,entropy, QM methods,and sampling on MM‐PBSA,MM‐GBSA,and QM/MM‐GBSA ligand binding energies of F. tularensis enoyl‐ACP reductase (FabI)

To validate a method for predicting the binding affinities of FabI inhibitors, three implicit solvent methods, MM‐PBSA, MM‐GBSA, and QM/MM‐GBSA were carefully compared using 16 benzimidazole inhibitors in complex with Francisella tularensis FabI. The data suggests that the prediction results are sensitive to radii sets, GB methods, QM Hamiltonians, sampling protocols, and simulation length, if only one simulation trajectory is used for each ligand. In this case, QM/MM‐GBSA using 6 ns MD simulation trajectories together with GB^neck2, PM3, and the mbondi2 radii set, generate the closest agreement with experimental values (r² = 0.88). However, if the three implicit solvent methods are averaged from six 1 ns MD simulations for each ligand (called “multiple independent sampling”), the prediction results are relatively insensitive to all the tested parameters. Moreover, MM/GBSA together with GB^HCT and mbondi, using 600 frames extracted evenly from six 0.25 ns MD simulations, can also provide accurate prediction to experimental values (r² = 0.84). Therefore, the multiple independent sampling method can be more efficient than a single, long simulation method. Since future scaffold expansions may significantly change the benzimidazole's physiochemical properties (charges, etc.) and possibly binding modes, which may affect the sensitivities of various parameters, the relatively insensitive “multiple independent sampling method” may avoid the need of an entirely new validation study. Moreover, due to large fluctuating entropy values, (QM/)MM‐P(G)BSA were limited to inhibitors’ relative affinity prediction, but not the absolute affinity. The developed protocol will support an ongoing benzimidazole lead optimization program. © 2015 Wiley Periodicals, Inc.     

Deposition of Diamond-like Carbon Films using Graphite Sputtering in Neon Dense Plasma

This paper reports the deposition of diamond-like carbon (DLC) films on Si <100>, using a low energy (1.45 kJ) dense plasma focus assisted sputtering of graphite insert at the tip of the tapered anode. The substrates are placed in front of the anode at different axial and angular positions and are exposed to multiple focus shots. The information regarding the DLC structure is acquired by using Raman spectroscopy. The spectra are characterized by two broad bands known as “G-band” and “D-band”. The results point towards the formation of DLC films with both sp³ (diamond like) and sp² (graphite like) domains. In X-ray diffraction (XRD) pattern, no additional peak is observed except a peak at 2θ = 69° which corresponds to the silicon (Si) substrate. The intensity of Si peak is reduced after treatment indicating the deposition of amorphous carbon. Scanning electron microscopy (SEM) results demonstrate that the smoothness of the film increases with increasing the substrate angular positions with respect to the anode axis. Energy dispersive X-ray (EDX) analysis reveals that the films deposited at lower axial and angular positions are thicker which is complemented by the cross-sectional views of the films.