Modeling and simulation of experimentally fabricated QDSSC using ZnS as light absorbing and blocking layer

Abstract—Two main factors which limit the power conversion efficiency of solar cells are light absorption and recombination processes. In photovoltaic (PV) devices, low energy photons cannot be absorbed and excite electrons from valance band to conduction band, hence do not contribute to the current. On the other hand, high energy photons cannot be efficiently used due to a poor match to the energy gap. Existence of charge recombination in PV devices causes the low conversion performance, which is indicated by the low open-circuit voltage (V _OC ). Using a blocking layer in system could effectively reduce the recombination of charge carriers. In this study, we simulated a solar cell with ITO/ZnO/P3HT&PCBM/Ag structure. To prevent the charge recombination, a ZnS QD layer was used which acts as a light absorbing and a recombination blocking layer in the ITO/ZnO film/ZnS QD/P3HT&PCBM/Ag structure. The simulated J–V characteristics of solar cells showed a close match with the experimental results. Simulate data showed an increase of conversion efficiency in ZnS QDSSC from 1.71 to 3.10%, which is relatively 81.28% increase.     

Tetra­butyl­bis(N‐phthaloyl­glycinato)­distannoxane dimer

The crystal structure of the title compound, [Sn₄(C₄H₉)₈(C₁₀H₆NO₄)₄O₂], contains centrosymmetric dimers. It contains a central Sn₂O₂ core with the O atoms bonded to two di­butyl­bis(N‐phthaloyl­glycinato)­tin units. The Sn atoms of the core are six‐coordinate in a skew trapezoidal bipyramidal geometry, while the exocyclic Sn atoms are essentially five‐coordinate in a distorted trigonal geometry. The Sn—C distances lie in a narrow range of 2.120 (5)–2.138 (4) Å.     

Modulation of ion sound excitations in electron–ion plasmas with double spectral index distribution function

Theoretical investigation of amplitude modulation of ion sound waves is presented here for an electron–ion plasma where the electrons are dictated by the double spectral index (r, q) distribution function. Using the standard reductive perturbative technique, a non-linear Schrödinger (NLS) equation is derived that describes the evolution of modulated ion sound envelope excitations. Stability analysis of the NLS equation shows that the ion sound waves remain stable for the flat-topped and kappa-like distributions, but they can become unstable for the spiky electron velocity distribution. It is shown that changing the electron population in regions of low and high phase space density regions results in remarkable features that have no equivalent in ion sound waves with Boltzmannian electrons. Different types of localized ion sound excitations are plotted for the different shapes of the distribution functions controlled by the double spectral indices, and the underlying physics is discussed in detail. The present investigation may be beneficial to understand ion sound excitations in space plasmas where the distribution functions of the shapes presented here are frequently encountered by the satellite missions.     

A Review of Twenty Years of Research on the Regulation of Signaling Pathways by Natural Products in Breast Cancer

Breast cancer (BC) is the second leading cause of death among women, and it has become a global health issue due to the increasing number of cases. Different treatment options, including radiotherapy, surgery, chemotherapy and anti-estrogen therapy, aromatase inhibitors, anti-angiogenesis drugs, and anthracyclines, are available for BC treatment. However, due to its high occurrence and disease progression, effective therapeutic options for metastatic BC are still lacking. Considering this scenario, there is an urgent need for an effective therapeutic strategy to meet the current challenges of BC. Natural products have been screened as anticancer agents as they are cost-effective, possess low toxicity and fewer side effects, and are considered alternative therapeutic options for BC therapy. Natural products showed anticancer activities against BC through the inhibition of angiogenesis, cell migrations, proliferations, and tumor growth; cell cycle arrest by inducing apoptosis and cell death, the downstream regulation of signaling pathways (such as Notch, NF-κB, PI3K/Akt/mTOR, MAPK/ERK, and NFAT-MDM2), and the regulation of EMT processes. Natural products also acted synergistically to overcome the drug resistance issue, thus improving their efficacy as an emerging therapeutic option for BC therapy. This review focused on the emerging roles of novel natural products and derived bioactive compounds as therapeutic agents against BC. The present review also discussed the mechanism of action through signaling pathways and the synergistic approach of natural compounds to improve their efficacy. We discussed the recent in vivo and in vitro studies for exploring the overexpression of oncogenes in the case of BC and the current status of newly discovered natural products in clinical investigations.     

Elongational viscosity of LDPE with various structures: employing a new evolution equation in MSF theory

Molecular stress function theory with new strain energy function is used to analyze transient extensional viscosity data of seven low-density polyethylene (LDPE) melts with various molecular structures as published by Stadler et al. (Rheol Acta 48:479–490, 2009) Pivokonsky et al. (J Non Newton Fluid Mech 135:58–67, 2006) and Wagner et al. (J Rheol 47(3):779–793, 2003). The new strain energy function has three nonlinear viscoelastic material parameters and assumes that the total stored energy of a branched molecule is given by different backbone and side chains stretching. The model parameters have been fitted for each LDPE in order to correlate with the supposed macromolecular structure expected from the type of synthesis. Most probable molecular structures for these LDPEs are comb and Cayley tree structures for respectively low- and high-molecular weight parts.     

Coinage Metal Complexes of a Tellurium Diimide: cis→trans Isomerization and Metal–Metal Interactions

The different coordination behavior of the ligand tBuN=Te(μ-NtBu)₂Te=NtBu (L) towards Cu⁺ and Ag⁺ results from a cis→trans isomerization. The two Cu⁺ ions in [Cu₂L₃]²⁺ (shown schematically) bridge trans and cis isomers of the ligand, whereas the Ag⁺ ions in [Ag₂L₂]²⁺ link two trans ligands and exhibit a weak Ag⋅⋅⋅Ag interaction.     

Isolation,Characterization and Anticancer Activity of Two Bioactive Compounds from Arisaema flavum (Forssk.) Schott

Medicinal plants play important role in the public health sector worldwide. Natural products from medicinal plants are sources of unlimited opportunities for new drug leads because of their unique chemical diversity. Researchers have focused on exploring herbal products as potential sources for the treatment of cancer, cardiac and infectious diseases. Arisaema flavum (Forssk.) is an important medicinal plant found in the northwest Himalayan regions of Pakistan. It is a poisonous plant and is used as a remedy against snake bites and scorpion stings. In this study, two bioactive compounds were isolated from Arisaema flavum (Forssk.) and their anticancer activity was evaluated against human breast cancer cell line MCF-7 using an MTT assay. The crude extract of Arisaema flavum (Forssk.) was subjected to fractionation using different organic solvents in increasing order of polarity. The fraction indicating maximum activity was then taken for isolation of bioactive compounds using various chromatographic and spectroscopic techniques such as column chromatography, thin-layer chromatography (TLC), gas chromatography–mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Crude extract of Arisaema flavum (Forssk.), as well as various fractions extracted in different solvents such as n-hexane, chloroform and ethyl acetate, were tested against human breast cancer cell line MCF-7 using an MTT assay. The crude extract exhibited significant dose-dependent anticancer activity with a maximum activity of 78.6% at 500 µg/mL concentration. Two compounds, hexadecanoic acid ethyl ester with molecular formula C₁₈H₃₆O₇ and molar mass 284 and 5-Oxo-19 propyl-docosanoic acid methyl ester with molecular formula C₂₆H₅₀O₃ and molecular mass 410, were isolated from chloroform fraction. These compounds were tested against the MCF-7cell line for cytotoxic activity and exhibited a significant (p < 0.00l) decrease in cell numbers for MCF-7 cells with IC₅₀ of 25 µM after 48 h of treatment. Results indicated that Arisaema flavum (Forssk.) possesses compounds with cytotoxic activity that can further be exploited to develop anticancer formulations.     

Acousto-mechanical behaviour of ex-vivo skin: Nonlinear and viscoelastic properties

The mechanical behaviour of skin is significant for some applications including dermatology, surgery, and impact biomechanics science. In this work, we have investigated the study of the acousto-mechanical viscoelastic properties of skin. For that, both tensile-relaxation and ultrasonic tests were conducted on porcine tissue samples in fibre directions. To understand the complex skin aging phenomena, we used strength tensile test correlated with the Nonlinear Time Reversal signal processing tool extension “TR-NEWS”. Uniaxial tensile tests were carried out at a strain rate of $5?{10}^{?3}\text{ mm}{\text{s}}^{?1}$ on skin using a load-relaxation-discharge load path with increasing amplitude and offset. This work is also under way to extend the frequency range of ultrasounds to 50 MHz. Digital Image Correlation was used for 2D strain measurement of the dermis. From this analysis, we conclude that fresh porcine skin should be modelled as a nonlinear viscoelastic material with strain-rate dependence. The obtained hysteresis loop shall be taken as significant skin damage.     

(Benzyl isocyanide)gold(I) pyrimidine‐2‐thiolate complex: Synthesis and biological activity

The reaction of [(Me₂S)AuCl] with an equimolar amount of benzyl isocyanide (PhCH₂NC) ligand led to the formation of complex [(PhCH₂NC)AuCl] ( 1 ). The solid‐state structure of 1 was determined using the X‐ray diffraction method. Through a salt metathesis reaction, the chloride ligand in 1 was replaced by pyrimidine‐2‐thiolate (SpyN^?) to afford the complex [(PhCH₂NC)Au(η¹‐S‐Spy)] ( 2 ), which was characterized spectroscopically. The cytotoxic activities of 1 and 2 were evaluated against three human cancer cell lines: ovarian carcinoma (SKOV3), lung carcinoma (A549) and breast carcinoma (MCF‐7). Complex 2 showed higher cytotoxicity than cisplatin against SKOV3 and MCF‐7 cancer cell lines. It showed a strong anti‐proliferative activity with IC₅₀ of 7.80, 6.26 and 6.14 μM, compared with that measured for cisplatin which was 7.62, 12.36 and 11.47 μM, against A549, SKOV3 and MCF‐7 cell lines, respectively. The induction of cellular apoptosis by 2 was also studied on MCF‐7 cell line. Our results indicated that 2 could induce apoptosis in cancerous cells in a dose‐dependent manner.     

Stereoselective synthesis of 3,4-di-substituted mercaptolactones via photoredox-catalyzed radical addition of thiophenols

A visible light mediated radical addition of thiophenols on 4-phenylbut-3-enoic acids to give diastereoselective synthesis of 3,4-disubstituted γ-lactones is reported. The reaction precludes the conventional prerequisite of conjugate addition. Furthermore, the lactones were successfully utilized in the synthesis of γ-ketoamides.