Algal extracts based biogenic synthesis of reduced graphene oxides (rGO) with enhanced heavy metals adsorption capability

Shahbaz Ahmad,Aftab Ahmad,Sikandar Khan,Shujaat Ahmad,Idrees Khan,Shah Zada,Pengcheng Fu 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

Efficient reduction of GO was performed, using cellular extracts of three algal strains. The rGO werecharacterized by SEM, TEM, UV-Visible spectroscopy, XRD, FTIR, Raman spectroscopy, Zeta potential andredox potentials. The rGO were then used as decontaminating agents for heavy metals (Cu and Pb), inwaste water. GO reduced via JSC-1 have removed up to 93% Cu and 82% Pb (adsorption capacity of93 mg g 1 and 82 mg g 1, respectively), by 211-9a have removed 74% (74 mg g 1) Cu and 89% (89 mg g 1)Pb, while by 211-11n have adsorbed 91% (91 mg g 1) Cu and 95% Pb (95 mg g 1), within 30 min.

A Survey of Rate-Adaptation Schemes for IEEE 802.11 Compliant WLANs

( Shahbaz Khan ),( Sadiq Ullah ),( Aziz Ahmed ),( Sahibzada. A. Mahmud ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.3

The IEEE 802.11 compliant stations can transmit at multiple transmission rates. Selection of an appropriate transmission rate plays a significant role in determining the overall efficiency of a communication system. The technique which determines the channel state information and accordingly selects an appropriate transmission rate is called rate-adaptation protocol. The IEEE 802.11 standard does not provide standard specification for implementing a rate-adaptation protocol for its multi-rate capable wireless stations. Due to the lack of standard specification, there is a myriad of rate-adaptation protocols, proposed by industry and various research institutes. This paper surveys the existing rate-adaptation schemes, discusses various features which contribute significantly in the process of rate-adaptation, the timing constraints on such schemes, and the performance gains in terms of throughput, delay and energy efficiency; which can be gained by the use of rate-adaptation. The paper also discusses the implication of rate-adaptation schemes on the performance of overall communication and identifies existing research challenges in the design of rate-adaptation schemes.

Biotoxicity assessment of pyrene in soil using a battery of biological assays.

Khan, Muhammad Imran,Cheema, Sardar Alam,Tang, Xianjin,Shen, Chaofeng,Sahi, Shahbaz Talib,Jabbar, Abdul,Park, Joonhong,Chen, Yingxu Springer-Verlag 2012 Archives of environmental contamination and toxico Vol.63 No.4

<P>A test battery, composed of a range of biological assays, was applied to evaluate the ecological health of soil aged for 69 days and spiked with a range of pyrene levels (1.04, 8.99, 41.5, 72.6, 136, and 399 μg g(-1) dry soil; Soxhlet-extracted concentrations after 69 days of aging). Chinese cabbage (Brassica rapa), earthworm (Eisenia fetida), and bacteria (Vibrio fischeri) were used as test organisms to represent different trophic levels. Among the acute ecotoxicity bioassays used, the V. fischeri luminescence inhibition assay was the most sensitive indicator of pyrene toxicity. We observed >8 % light inhibition at the lowest concentration (1.04 μg g(-1)) pyrene, and this inhibition increased to 60 % at 72.6 μg g(-1). The sensitivity ranking for toxicity of the pyrene-contaminated soil in the present study was in the following decreasing order: root elongation of Chinese cabbage < earthworm mortality (14 days) < earthworm mortality (28 days) < luminescence inhibition (15 min) < luminescence inhibition (5 min). In addition, genotoxic effects of pyrene were also evaluated by using comet assay in E. fetida. The strong relationship between DNA damage and soil pyrene levels showed that comet assay is suitable for testing the genotoxicity of pyrene-polluted soil. In addition, tail moment was well correlated with soil pyrene levels (r (2) = 0.99). Thus, tail moment may be the most informative DNA-damage parameter representing the results of comet assay. Based on these results, the earthworm DNA damage assay and Microtox test are rapid and sensitive bioassays and can be used to assess the risk of soil with low to high levels of hydrocarbon pollution. Furthermore, an analysis of the toxic effects at several trophic levels is essential for a more comprehensive understanding of the damage caused by highly contaminated soil.</P>

Variability and Predictability of Summer Monsoon Rainfall over Pakistan

Adnan Muhammad,Khan Firdos,Rehman Nadia,Ali Shaukat,Hassan Sher Shah,Dogar Muhammad Mubashar,Mehmood Shahbaz,Hasson Shabehul 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.1

Rainfall variability associated with the South Asian Summer Monsoon has increased in recent decades, particularly at the northwestern monsoon margins over Pakistan, leading to more frequent and intense hydro-meteorological extremes that have adversely affected the agrarian economy, water and food security in the country. Devising effective strategies to ensure sustainable development in Pakistan thus requires that the monsoonal rainfall be predicted on an inter-annual scale. Here, we predicted the inter- and intra-annual variability of the monsoonal rainfall over Pakistan and its possible drivers using a linear statistical forecast model of the principal component (PC) regression analysis. For this purpose, highly correlated PCs of the National Centre for Environmental Prediction (NCEP) based sea level pressure, horizontal and meridional winds to the observed rainfall for the period 2001–2013 were ingested in a stepwise multiple regression model, which was further validated for the duration of 2014–2015. Our results suggest that featuring correlation coefficient, mean absolute error, mean bias, and root mean square error of 0.75, 42.23, −14.92 and 60.65, respectively, the model exhibits robust skill in predicting the inter-annual monsoonal rainfall variability at its extreme northwestern margins over Pakistan.

Effect of variable degrees of jejunal resection upon different clinico-biochemical parameters in dogs

Dilawer, Muhammad Sohail,Khan, Muhammad Arif,Abidin, Zain ul,Azeem, Shahan,Majeed, Khalid Abdul,Shahbaz, Adeel,Khan, Aamir Riaz The Korean Society of Veterinary Science 2011 大韓獸醫學會誌 Vol.51 No.4

Dogs are considered to be the best companions of human beings due to their loyalty, obedience and pleasant disposition. Jejunum is the largest part of small intestine mainly involved in absorption of nutrients. Jejunal resection up to 80% allows normal weight gain while resection up to 90% increased morbidity and mortality. In the present study, 20 dogs were divided into 4 groups based on the degree of jejunal resection i.e. A (70% resection), B (80% resection) and C (100% resection) while group D served as control. Dogs in the 70% and 80% jejunal resection group showed normal growth and function while 100% jejunal resection resulted in weight loss and alteration of hematological and biochemical parameters.

An Improved Algorithm for AC Impedance Extraction

Muhammad Saad,Yongfeng Ju,Shahbaz Khan,Husan Ali,Abdul Wadood,Sang Bong Rhee 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6

The overall system stability of interconnected electrical and electronic systems is associated with the input and output impedances of each individual system, therefore, accurate AC impedance measurement for a linear and nonlinear systems are imperative. These impedances are normally measured using small-signal frequency injection techniques. However, the harmonic transfers from the output side to the input side and vice versa deteriorates the measured results, making them ambiguous. These harmonic transfers cause the problems of frequency aliasing as well as spectral leakages leading to inaccurate measurements of results. In order to achieve the precise and accurate results, there is a need to adopt such an impedance measuring technique which is the best among the available techniques. A new algorithm is proposed to modify the range of frequencies of interest and inject such small-signal frequencies which do not interfere with the system harmonics. The measurement of the AC impedance of the three-phase RL circuit utilizing three diff erent small-signal injection techniques is performed. From the results displayed, it is clear that all the techniques perform well, therefore, the most simple, single phase line-current injection was selected for the AC impedance measurement of the nonlinear switching circuit such as sixpulse rectifi er. The issues discussed above are more serious in nonlinear switching circuit because of the presence of higher order switching harmonics in the circuit. The proposed algorithm is applied to measure the output-impedance of the threephase AC power supply as well as the AC input-impedance of the six-pulse rectifi er. These results of the switch vs average model and that of average model vs. experimental prototype are displayed for comparison, and it is clear that the proposed algorithm off ers much-improved results.

ON COUPLED COINCIDENCE POINTS IN MULTIPLICATIVE METRIC SPACES WITH AN APPLICATION

Ibtisam Mutlaq Alanazi,Qamrul Haque Khan,Shahbaz Ali,Tawseef Rashid,Faizan Ahmad Khan 경남대학교 수학교육과 2023 Nonlinear Functional Analysis and Applications Vol.28 No.3

In this manuscript, we prove the existence of the coupled coincidence point by using $g$-couplings in multiplicative metric spaces (MMS). Further we show that existence of a fixed point in ordered MMS having $t$-property. Finally, some examples and application are presented for attesting to the credibility of our results.

The moderating role of intrinsic motivation in cloud computing adoption in online education in a developing country: a structural equation model

Fakhar Shahzad,GuoYi Xiu,Imran Khan,Muhammad Shahbaz,Muhammad Usman Riaz,Adnan Abbas 서울대학교 교육연구소 2020 Asia Pacific Education Review Vol.21 No.1

In the provision of massive open online courses (MOOCs), cloud computing services enable students to synchronize their study materials anywhere, anytime, and using any device, which can improve learning performance and strengthen the teacher–student relationship via knowledge sharing. This study builds on the technological–organizational–environmental (TOE) framework and aims to identify the influencing factors of cloud computing adoption in educational settings for the provision of MOOCs. Another aim is to determine how intrinsic motivation moderates individual intention. Therefore, our study conceptualized a model that is supported by an empirical analysis of 232 respondents and takes into account the technological, organizational, and environmental impacts on individual attitudes toward adopting cloud computing in education. We evaluate the study hypotheses using structural equation modeling. The results demonstrate significant relationships between the technological and organizational constructs and attitudes toward the use of cloud computing. Meanwhile, competitive pressure from the environment has not been identified in any relationship with individual attitudes in government universities. The results provide new directions for policymakers to consider in the implementation of CC systems for the provision of MOOCs in developing countries. We also discuss potential implications, contributions, and suggestions for future research.

Analytic functions related with q-conic domain and associated with a convolution operator

Basem Aref Frasin,Ala Amourah,Syed Ghoos Ali Shah,Saqib Hussain,Shahbaz Khan,Fethiye Muge Sakar 한국전산응용수학회 2023 Journal of applied mathematics & informatics Vol.41 No.6

In this paper, we defined some new classes of analytic functions in conic domains. We investigate some important properties such as necessary and sufficient conditions, coefficient estimates, convolution results, linear combination, weighted mean, arithmetic mean, radii of starlikeness and distortion for functions in these classes. It is important to mentioned that our results are generalization of number of existing results in the literature.

Reduced Order Identification and Stability Analysis of DC-DC Converters

Ali, Husan,Zheng, Xiancheng,Wu, Xiaohua,Zaman, Haider,Khan, Shahbaz The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

This paper discusses the measurement of frequency response functions for various dc-dc converters. The frequency domain identification procedure is applied to the measured frequency responses. The identified transfer functions are primarily used in developing behavioral models for dc-dc converters. Distributed power systems are based upon such converters in cascade, parallel and several other configurations. The system level analysis of a complete system becomes complex when the identified transfer functions are of high order. Therefore, a certain technique needs to be applied for order reduction of the identified transfer functions. During the process of order reduction, it has to be ensured that the system retains the dynamics of the full order system. The technique used here is based on the Hankel singular values of a system. A systematic procedure is given to retain the maximum energy states for the reduced order model. A dynamic analysis is performed for behavioral models based on full and reduced order frequency responses. The close agreement of results validates the effectiveness of the model order reduction. Stability is the key design objective for any system designer. Therefore, the measured frequency responses at the interface of the source and load are also used to predict stability of the system.