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991.
Muhammad Bachal Korai Ghulam Abbas Shar Gul Afshan Soomro Muhammad Aslam Korai Maqsood Ahmed Mirbahar Abdul Samad Nisar Abbas Shar 《印度化学会志》2022,99(4):100360
A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 104 L mol?1cm?1 and 2.6 ngcm?2 at λmax 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL?1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]2. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples. 相似文献
992.
Abdullah Abdulhameed Mohd Nazim Mohtar Mohd Nizar Hamidon Izhal Abdul Halin 《Electrophoresis》2022,43(3):487-494
The assembly of carbon nanotubes (CNTs) across planner electrodes using dielectrophoresis (DEP) is one of the standard methods used to fabricate CNT-based devices such as sensors. The medium drag velocity caused by electrokinetic phenomena such as electrothermal and electroosmotic might drive CNTs away from the deposition area. This problem becomes critical at large-scale electrode structures due to the high attenuation of the DEP force. Herein, we simulated and experimentally validated a novel DEP setup that uses a top glass cover to minimize the medium drag velocity. The simulation results showed that the drag velocity can be reduced by 2–3 orders of magnitude compared with the basic DEP setup. The simulation also showed that the optimum channel height to result in a significant drag velocity reduction was between 100 μm and 240 μm. We experimentally report, for the first time, the assembly and alignment of CNT bridges across indium tin oxide (ITO) electrodes with spacing up to 125 μm. We also derived an equation to optimize the CNT's concentration in suspensions based on the electrode gap width and channel height. The deposition of long CNTs across ITO electrodes has potential use in transparent electronics and microfluidic systems. 相似文献
993.
The higher-order, low-amplitude inertial Alfvén wave (IAW) dressed soliton and chaos are investigated in a magnetized plasma. In the linear limit, the dispersion relation for propagation of IAWs in plasmas is also obtained in the presence of electron thermal effects and illustrated numerically. It is found that the electron inertial length plays an important role for wave dispersion effects and its phase speed is increased on including the electron temperature in the model. The reductive perturbation method is employed to obtain the first-order IAW Korteweg–de Vries (KdV) soliton and second-order dressed soliton solutions analytically, which gives electron density dip (or rarefactive) structure and moves with super Alfvénic speed in plasmas. The numerical illustrations of the KdV and dressed IAW solitons are also presented by using the laboratory and space plasma parameters given in the literature. Furthermore, a numerical study of quasi-periodicity and chaotic behaviour of IAWs in the presence of external periodic force is also discussed in detail. The effects of plasma beta (which depends on plasma density, electron temperature, and magnetic field intensity) and obliqueness of the wave propagation on the formation of nonlinear Alfvénic wave structures have also been presented. 相似文献
994.
Two types of mixing layers produced from two streams merging at 0° and 18° have been investigated. Each type of mixing layer
was produced with velocity ratios 0.7, 0.8 and 0.9 and measurements were taken at six streamwise locations. The boundary layers
were untripped and initially turbulent in all cases. Both types of mixing layers were found to attain a self-similar state
for velocity ratios 0.7 and 0.8 but failed for 0.9 within the measurement domain. It appears that the mixing layer flow becomes
self-similar earlier when merging at 18° than at 0°. With increasing velocity ratio, the development distance was increased
and the splitter wake played a dominant role in the development of the mixing layers. The mixing layers from non-parallel
merging streams (18°) were found to have higher growth in the near-field than those from parallel merging streams (0°). Both
types of mixing layers were found to decrease in growth with increasing velocity ratio, though they spread more at the high-speed
side.
Published online: 23 November 2002 相似文献
995.
996.
Sjahro Noerhidajat Yunus Robiah Abdullah Luqman Chuah Rashid Suraya Abdul Asis Ahmad Jaril Akhlisah Z. N. 《Cellulose (London, England)》2021,28(12):7521-7557
Cellulose - Inappropriate discharge of industrial wastewater and household effluent has led to an accumulation of hazardous organic substances, oil and grease, heavy metal ions, dyes, and leftover... 相似文献
997.
Traditional risk measurements have proven inadequate in capturing tail risk and nonlinear correlation. This study proposes a novel approach to measure financial risk in the Internet finance industry: a new Value-at-Risk (VaR) measurement based on quantile regression neural network (QRNN). Sparrow Search Algorithm (SSA) is utilized to optimize the QRNN model, which improves the model's performance in predicting internet finance risk. By comparing the TGARCH-VaR and QR-VaR approaches, our study demonstrates the effectiveness of the QRNN-VaR approach and its potential to improve the accuracy of risk prediction in the Internet finance industry. This study further examines and compares the risks between the traditional and internet finance industries. It also considers the unique impact of COVID-19 on industry risk based on statistical testing for differences and machine learning models. Our results indicate that the level of risk in the Internet finance industry is higher than in the traditional finance industry. Moreover, COVID-19 has contributed to increased risk within the Internet finance industry. These findings have significant implications for investors and policymakers seeking to better understand and manage risks within the Internet finance industry, particularly in the ongoing COVID-19 pandemic. 相似文献
998.
Dr. Abdul Aziz Syed Shaheen Shah Dr. Mohammad A. Jafar Mazumder Dr. Munetaka Oyama Dr. Abdul-Rahman Al-Betar 《化学:亚洲杂志》2021,16(12):1570-1583
There is an overwhelming desire to develop new sulfide oxidation electrocatalysts that perform at low potentials and exhibit high current density for the removal and efficient sensing of sulfide. This article describes a comparative electrochemical analysis of various commercially available carbon materials and polymer/surfactant composite electrocatalysts for direct electrooxidation of sulfide in an aqueous solution. The composites were prepared from five different carbon materials multiwalled carbon nanotubes, fullerene-C60, graphene, glassy carbon, and carbon nanofibers (CNF) and four different polymers: chitosan, polyvinylidene fluoride, Nafion, and indigenously synthesized poly[2-(methacryloyloxy)ethyl] trimethylammonium chloride (PMTC). The carbon@polymer composites were prepared by a simple ultrasonication technique, and the electrodes were prepared by drop-drying the prepared composite on indium tin oxide (ITO) substrates. The CNF@PMTC showed the highest positive zeta potential that allowed an accumulation of many negatively charged sulfide ions at the CNF@PMTC surface. Cyclic voltammetry was used for the electrooxidation of sulfide in an aqueous solution of tris buffer (0.05 M; pH 8.0) and KNO3 (0.1 M). The lowest sulfide oxidation peak potential (i. e., −51 mV vs. standard hydrogen electrode) with a high catalytic current response (730 μA/cm2) of the CNF@PMTC-modified ITO electrode among the tested and previously reported carbon-based electrode materials make it ideal for direct sulfide electrooxidation. Taking this and its simple preparation method into account, CNF@PMTC can be considered a benchmark carbon-based electrocatalyst for sulfide oxidation. 相似文献
999.
Nadeem Muhammad Muhammad Zia-ul-Haq Amjad Ali Sumaira Naeem Azeem Intisar Dongxue Han Hairong Cui Yan Zhu Jia-Lun Zhong Abdul Rahman Binnian Wei 《Arabian Journal of Chemistry》2021,14(3):102972
Ion chromatography (IC) is a well-known technique for trace determination of inorganic ions and small organic acids. Recently, it has also appeared as a promising alternative to reverse phase chromatography for the determination of polar pesticides and pharmaceutical drugs in various sample matrices. Therefore, this study aims to provide a comprehensive overview of the application of IC coupled to fluorescence (FLD) or UV detector for the determination of pesticides and pharmaceutical drugs in samples from all walks of life. Apart from advantages and limitations, a short comparison of IC-FLD/UV with other techniques especially reverse-phase chromatography was drawn to envision future research efforts in this direction. Finally, several related areas such as IC hyphenation with different detectors (spectroscopic and spectrometer), miniaturization, automation, green chemistry, mobile phase, column, sample preparation, etc., were discussed to highlight its application for the determination of a wide range of analytes in the complex sample matrix. 相似文献
1000.
Homood M. As Sobeai Adam A.A. Sulaiman Saeed Ahmad Abdul Rajjak Shaikh Ridwan Sulaimon Moureq R. Alotiabi Fahad AlZoghaibi Ali Osman Altoum Anvarhusein A. Isab Ali R. Alhoshani 《Arabian Journal of Chemistry》2021,14(7):103245
New therapeutic options are crucially for most cancers, particularly those with poor clinical outcomes. Five new derivatives of cisplatin-containing selenone ligands with the general formula, cis-[Pt(NH3)2(Selenone)2](NO3)2 (1–5) were synthesized and characterized using elemental analysis, Infrared, and nuclear magnetic resonance (1H, 13C & 77Se) spectroscopy. Spectroscopic and computational data supported the coordination of selenones to platinum(II). The structures of the complexes were predicted using density functional theory calculations. Molecular docking studies were carried out using the AutoDock Tools docking program. The in vitro cytotoxicity of these complexes and cisplatin against three human cancer cell lines, HeLa, A549, and HCT116 was investigated using the MTT assay. The best candidate complex, complex 3, was subjected to mechanistic assessments, including miRNA profiling, PI3K deactivation, and induction of apoptosis. Docking studies showed that all the newly synthesized platinum(II) complexes interacted with the minor DNA groove. The synthesized complexes showed promising cytotoxic effects against the tested cell lines. Complex 3 modulated the miRNA expression signature in A549 cells. Pathway enrichment analyses of differentially expressed miRNA gene targets identified the PI3K/AKT signaling pathway as a promising target. Complex 3 inhibited PI3K activity and induced apoptosis. Collectively, our study identified promising new platinum(II) derivatives such as complex 3, paving the way for future in vitro and in vivo validations and safety studies. 相似文献