New prenylated flavonoids from the leaves of Dodonea viscosa native to the Sultanate of Oman

AbstractTraditionally, in Oman, the whole plant is used to treat the body, including treatment of anaemia, arthritis and skin inflammation. Crude extracts were prepared from the leaves of Dodonea viscosa (D. viscosa) using different polarities of solvents to isolate flavonoid compounds from the highest activity crude extract of the selected plant species collected from AL-Jabal AL Akhdar, Nizwa. The plant samples were collected, processed and extracted with methanol using a hot extraction method. The prepared crude extract was dissolved in water and successively fractioned with different polarities of solvents to produce hexane, chloroform, ethyl acetate, butanol and water crude extracts. The chloroform crude extract was used for the isolation of flavonoid compounds by thin layer chromatography, column chromatography and preparative thin layer chromatography. The free radical scavenging activity of the isolated pure compound and the different polarities of crude extracts were determined using the 1,1-diphenyl-2-picrylhydrazyl method.The highest antioxidant activity in crude extracts from the leaves of D. viscosa was in the hexane and chloroform crude extracts, and the lowest activity was in the water crude extract, followed by hexane > chloroform > ethyl acetate > methanol > butanol > water crude extracts. One new prenylated flavonoid along with one known compound were isolated from the chloroform crude extract of D. viscosa and were identified by their chemical structures using mass spectrometry, one and two dimension nuclear magnetic resonance. The isolated pure compound also showed significant antioxidant activity against DPPH. This is the first report of antioxidant compounds in the leaves of D. viscosa. The results obtained from this study might be a good natural antioxidant from the selected plant crude extracts

Menghitung Jumlah Segitiga pada Sebuah Graf Menggunakan Brute Force Berdasarkan Verteks dengan OpenMP

aringan merupakan suatu istilah umum yang sedang berkembang pesat saat ini, umumnya jaringan merepresentasikan banyak tipe data pada berbagai bidang. Jaringan dapat direpresentasikan sebagai graf. Graf memuat sub graf yang dapat membentuk segitiga. Terdapat beberapa metode yang terkait untuk menghitung jumlah segitiga (Triangle counting), di antaranya algoritma brute force. Algoritma ini menghasilkan akurasi yang tinggi, tetapi membutuhkan komputasi yang sangat lama. Pada tugas akhir ini dilakukan analisis implementasi paralel terhadap brute force untuk menghitung jumlah segitiga pada graf dengan menggunakan Open MP dan secara distribusi data. Dengan diparalelkan secara distribusi data ini diperoleh speed up 2.28131 secara cyclic dan 2.23429 secara paralel biasa yang selisih speed up 0.04702 dimana cyclic cukup baik. </p

Nanocrystalline Silicon Solar Cells Deposited via Pulsed PECVD at 150°C Substrate Temperature

A series of experiments was carried out to compare the structural and electronic properties of intrinsic nanocrystalline silicon (nc-Si:H) thin films deposited via continuous wave (cw) and pulsed (p)-PECVD at 150°C substrate temperature. Working at this temperature allows for the easy transfer of film recipes from glass to plastic substrates in the future. During the p-PECVD process the pulsing frequency was varied from 0.2 to 50 kHz at 50% duty cycle. Approximately 15% drop in the deposition rate was observed for the samples fabricated in p-PECVD compared to cw-PECVD. The optimum crystallinity and photo (σph) and dark conductivity (σD) were observed at 5 kHz pulsing frequency, with ~10% rise in crystallinity and about twofold rise in the σph and σD compared to cw-PECVD. However, for both the cw and p-PECVD nc-Si:H films, the observed σph and σD were one to two orders and three orders of magnitude higher respectively than those reported in literature. The average activation energy (EA) of 0.16 ∓ 0.01 eV for nc-Si:H films deposited using p-PECVD confirmed the presence of impurities, which led to the observation of the unusually high conductivity values. It was considered that the films were contaminated by the impurity atoms after they were exposed to air. Following the thin film characterization procedure, the optimized nc-Si:H film recipes, from cw and p-PECVD, were used to fabricate the absorber layer of thin film solar cells. The cells were then characterized for J-V and External Quantum Efficiency (EQE) parameters. The cell active layer fabricated from p-PECVD demonstrated higher power conversion efficiency (η) and a maximum EQE of 1.7 ∓ 0.06 % and 54.3% respectively, compared to 1.00 ∓ 0.04 % and 48.6% respectively for cw-PECVD. However, the observed η and EQE of both the cells were lower than a reported nc-Si:H cell fabricated via p-PECVD with similar absorber layer thickness. This was due to the poor Short-circuit Current Density (Jsc), Open-circuit Voltage (Voc), and Fill Factor (FF) of the cw and p-PECVD cells respectively, compared to the reported cell. The low Jsc resulted from the poor photocarrier collection at longer and shorter wavelengths and high series resistance (Rseries). On the other hand, the low Voc stemmed from the low shunt resistance (Rsh). It was inferred that the decrease in the Rsh occurred due to the inadequate electrical isolation of the individual cells and the contact between the n – layer and the front TCO contact at the edge of the p-i-n deposition area. Additionally, the net effect of the high Rseries and the low Rsh led to a decrease in the FF of the cells

Synthesis and characterization of ZnO-decorated GO nanocomposite material with different ZnO loading through sol-gel method

This work aimed is to synthesis a well dispersed zinc oxide (ZnO) nanoparticles (NPs) decorated on graphene oxide (GO) nanosheet with a practical way by using sol-gel technique. Zinc acetate dehydrate (Zn(CH3COO) 2·2H2O) was used as precursor of ZnO and absolute ethanol as solvent. 1 weight percent (wt%), 5 wt%, 10 wt%, and 20 wt% of ZnO was decorated on GO nanosheet. A series of analysis was carried out to characterize the synthesized ZnO-decorated GO nanocomposite material. The results of XRD analysis show some long area of peak at 25° to 80° allocate for ZnO in the ZnO-decorated GO nanocomposite material. By performing zeta potential analysis, the findings show that there was increment of negative surface charge on ZnO-decorated GO nanocomposite material. The experiment result also found that the hydrodynamic particle size of ZnO-decorated GO nanocomposite material become larger when high ZnO loaded. FESEM micrographs demonstrated that spherical-shaped of ZnO NPs appeared on the GO nanosheet with further proved by EDX where the content of ZnO-decorated GO nanocomposite material was composed by 71.3 wt% of C, 17 wt% of O, and additional element of 11.7 wt% of Zn. Thus, it can summarize that the synthesized ZnO-decorated GO nanocomposite material was high in purity. The findings in this study proved that ZnO NPs loading in ZnO-decorated GO nanocomposite material were successfully synthesized by sol-gel method. A ZnO-decorated GO nanocomposite material with layering ZnO NPs on GO nanosheet was produced

Evaluation of serotonin serum level in cases of alopecia areata and vitiligo

Background: There are cutaneous illnesses that could be exacerbated or precipitated by stress, including alopecia areata, psoriasis, and even vitiligo. Psychological sequelae mainly affected by serotonin have been studied among these patients.Objective: Assessment of blood serotonin levels in alopecia areata and vitiligo patients for psychological impacts. Patients and Methods: 15 individuals with vitiligo, 15 with alopecia areata, and 15 healthy age and sex matched controls were studied in this study. A modified version of the Social Readjustment Rating Scale (SRRS) was used to quantify the stress index, and blood serotonin levels were also measured to study the role of stress in alopecia areata and vitiligo.Results: Patients who had alopecia areata as well as vitiligo had considerably greater serum serotonin levels than controls. In the vitiligo group, there was a strong positive connection between serum serotonin, the vitiligo area scoring index (VASI) score, and the stress index. On the other hand, no positive correlation was found between serum serotonin and both severity of alopecia tool (SALT) score and stress index in alopecia areata group. Conclusion: In both alopecia areata and vitiligo, psychological stress appears to play a significant role as a triggering factor and we should pay attention to psychiatric role to get proper treatment for such chronic diseases

Arabic automatic continuous speech recognition systems

MSA is the current formal linguistic standard of Arabic language, which is widely taught in schools and universities, and often used in the office and the media. MSA is also considered as the only acceptable form of Arabic language for all native speakers [I]. As recently, the research community has witnessed an improvement in the performance of ASR systems, there is an increasingly widespread use of this technology for several languages of the world. Similarly, research interests have grown significantly in the past few years for Arabic ASR research. It is noticed that Arabic ASR research is not only conducted and investigated by researchers in the Arab world, but also by many others located in different parts of the \vorld especially the western countries

Review of multicast QoS routing protocols for mobile ad hoc networks

A Mobile Ad hoc NETwork (MANET) is consisting of a collection of wireless mobile nodes, which form a temporary network without relying on any existing infrastructure or centralized administration. Since the bandwidth of MANETs is limited and shared between the participating nodes in the network, it is important to efficiently utilize the network bandwidth. Multicasting can minimize the link bandwidth consumption and reduce the communication cost by sending the same data to multiple participants. Multicast service is critical for applications that need collaboration of team of users. Multicasting in MANETs becomes a hot research area due to the increasing popularity of group communication applications such as video conferencing and interactive television. Recently, multimedia and group-oriented computing gains more popularity for users of ad hoc networks. So, effective Quality of Service (QoS) multicasting protocol plays significant role in MANETs. In this paper, we are presenting an overview of set of the most recent QoS multicast routing protocols that have been proposed in order to provide the researchers with a clear view of what has been done in this field