Enhanced photoelectrochemical performance of quantum dot-sensitized solar cell using Cu2+ co-doped CdS and CdSe nanoscrystals.

Today, nanoscrystals are researched and developed very quickly because of their advantages in many areas of life. One of the potential applications is quantum dot-sensitized solar cells. This is a green, clean, environmentally friendly cell, and has been studied by scientists since 2000. In this study, we fabricated photoanodes with Cu2+ ions co-doped into cadmium sulfide (CdS) and cadmium selenide (CdSe) nanoscrystals by successive ionic layer adsorption and reaction, and chemical bath deposition methods to improve absorption spectral intensity of films. The results showed that the absorption intensity increased by eight times compared with our previous results on Cu2+ ions doped with CdSe nanoscrystals. The CdS:Cu2+ film is optimized at 2% doping, the efficiency is 4.6819%, and the current density is 27.3501 mA.cm-2, which is higher when compared with the Cu2+ ion only doped into the CdSe quantum dot (19.915 mA.cm-2). In addition, the composition of the photoanode was determined by surface and cross-sectional field-emission scanning electron microscope images, and the structure of the film was determined by X-ray diffraction, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy. Finally, the film's optical properties were studied by ultraviolet-visible spectroscopy, photoluminescence spectroscopy and electrochemical properties by electrochemical impedance spectroscopy. The results obtained have been discussed and presented in great detail.

Empowering Intelligent Surfaces and User Pairing for IoT Relaying Systems: Outage Probability and Ergodic Capacity Performance.

The evolution of Internet of Things (IoT) networks has been studied owing to the associated benefits in useful applications. Although the evolution is highly helpful, the increasing day-to-day demands of mobile users have led to immense requirements for further performance improvements such as efficient spectrum utilization, massive device connectivity, and high data rates. Fortunately, reconfigurable intelligent surfaces (RIS) and non-orthogonal multiple access (NOMA) techniques have recently been introduced as two possible current-generation emerging technologies with immense potential of addressing the above-mentioned issues. In this paper, we propose the integration of RIS to the existing techniques (i.e., NOMA and relaying) to further enhance the performance for mobile users. We focus on a performance analysis of two-user group by exploiting two main performance metrics including outage probability and ergodic capacity. We provide closed-form expressions for both performance metrics to highlight how NOMA-aided RIS systems provide more benefits compared with the benchmark based on traditional orthogonal multiple access (OMA). Monte-Carlo simulations are performed to validate the correctness of obtained expressions. The simulations show that power allocation factors assigned to two users play a major role in the formation of a performance gap among two users rather than the setting of RIS. In particular, the strong user achieves optimal outage behavior when it is allocated 35% transmit power.

A new furanochromone from the leaves of Mimosa pigra.

Phytochemical study on the EtOAc-soluble extract of the leaves of Mimosa pigra led to the isolation of a new furanochromone, 6,8-dihydroxy-2-methyl-9H-furo[3,2-b]chromen-9-one (1), along with four known compounds (2-5). Their structures were elucidated based on the basis of the spectral interpretation. The plausible biosynthesis pathway for the formation of the new furanochromone was proposed. At a concentration of 100 µM, compound 1 showed no cytotoxicity against human MCF-7 breast cancer cell with a cell viability >50%.[Figure: see text].

A new lignan from the flowers of Hibiscus sabdariffa L. (Malvaceae).

From MeOH-soluble fraction of the flowers of Hibiscus sabdariffa (Malvaceae), one new lignan, (+)-4-O-methyl-5'-methoxy-secoisolariciresinol (1), together with four known compounds (2-5) were isolated. The structures were elucidated based on NMR spectroscopic analysis. The absolute configuration of 1 was determined based on the Cotton effects in the CD spectrum. Compounds 1, 3 and 4 showed antioxidant activities with the SC50 values of 56.9, 19.3 and 22.7 µM, respectively.

Pipercyclobutanamide D, a new member of the cyclobutanamide-type alkaloid, from the roots of Piper nigrum.

From the EtOH-soluble extract of the roots of Piper nigrum, one new dimeric alkamide, pipercyclobutanamide D (1) was isolated. Its structure was elucidated on the basis of NMR spectroscopic interpretation. The relative configuration of 1 was determined based on the NOESY analysis. Compound 1 showed α-glucosidase inhibitory activity with an IC50 value of 158.5 µM. In addition, compound 1 exhibited cytotoxicity against the MCF-7 and HepG2 cell lines with the IC50 values of 45.6 and 63.9 µM, respectively. Plausible biosynthetic pathway for the formation of 1 was proposed based on regioselective [2 + 2] cycloaddition reaction.

Two new meroterpenoids from the aerial parts of Ampelopsis cantoniensis (Vitaceae).

From EtOAc-soluble fraction of the aerial parts of Ampelopsis cantoniensis (Vitaceae), two new meroterpenoids named ampechromonol A (1) and ampechromonol B (2), together with five known compounds (3-7), were isolated. Their structures were elucidated based on NMR spectroscopic analysis. The plausible biosynthesis pathway for the formation of two new meroterpenoids was proposed. This research is the first isolation of meroterpenoids from Ampelopsis genus. Compounds 1 and 2 showed weak cytotoxicity against MCF-7 breast cancer cells.

Chemical constituents of Geum urbanum L. roots.

A new dehydrodigallic acid derivative (1), along with 19 known compounds, including 6 phenolic derivatives, 2 steroids and 11 triterpenoids were isolated from the ethanol extract of the root of Geum urbanum. Herein, there is the first report of steroid and triterpene in Geum urbanum. The purified metabolites were characterised by NMR spectroscopic and mass spectrometric analyses. The identification of the known compounds (2-20) was based on the comparison of their NMR spectroscopic features with previously published data. The structural characteristics of compound 1 were elucidated by comprehensive 1D and 2D NMR spectroscopic methods and acid hydrolysis.