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Influence of accelerated curing on the compressive strength of polymer-modified concrete

Frontiers of Structural and Civil Engineering 2022年第5期16卷 589-599页

作者： Izhar AHMAD Kashif Ali KHAN tahir AHMAD Muhammad ALAM Muhammad Tariq BASHIR College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Department of Civil Engineering Muslim Youth UniversityIslamabad 44000Pakistan Department of Civil Engineering CECOS University of IT&Emerging SciencesPeshawar 25000Pakistan Department of Civil Engineering University of Engineering&TechnologyMardan 23200Pakistan

In recent building practice,rapid construction is one of the principal ***,in designing concrete structures,compressive strength is the most significant of all *** 3-d and 7-d compressive strength reflects the strengths at early phases,the ultimate strength is *** effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate(EVA)at the later ***-Smirnov(KS)goodness-of-fit test was used to examine distribution of the *** compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28,56,90,120,210,and 365 *** accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression *** on the results of KS goodness-of-fit test,it was concluded that KS test statistics value(D)in each case was lower than the critical value 0.521 for a significance level of 0.05,which demonstrated that the data was normally *** on the results of compressive strength test,it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16%***,it was concluded that predicted compressive strength values lies within a 6%difference from the actual strength values for all the mixes,which indicates the practicability of the regression *** research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction polymer-modified concrete linear regression fit early age strength ethylene vinyl acetate

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Catalytic fast pyrolysis of walnut shell for alkylphenols production with nitrogen-doped activated carbon catalyst

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Frontiers of Environmental Science & Engineering 2021年第2期15卷 95-105页

作者： Shanwei Ma Hang Li Guan Zhang tahir Iqbal Kai Li Qiang Lu State Key Laboratory of Alternate Electric Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China Faculty of Agricultural Engineering&Technology PMAS-Arid Agriculture UniversityRawalpindi 46000Pakistan

Alkylphenols are a group of valuable phenolic compounds that can be derived from lignocellulosic *** this study,three activated carbons(ACs)were prepared for catalytic fast pyrolysis(CFP)of walnut shell to produce alkylphenols,including nitrogen-doped walnut shell-derived activated carbon(N/WSAC),nitrogen-doped rice husk-derived activated carbon(N/RHAC)and walnut shell-derived activated carbon(WSAC).Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)experiments were carried out to reveal the influences of AC type,pyrolytic temperature,and AC-to-walnut shell(AC-to-WS)ratio on the product *** showed that with nitrogen doping,the N/WSAC possessed stronger capability than WSAC toward the alkylphenols production,and moreover,the N/WSAC also exhibited better effects than N/RHAC to prepare *** the catalysis of N/WSAC,yields of alkylphenols were significantly increased,especially phenol,cresol and *** the increase of pyrolytic temperature,the alkylphenols yield first increased and then decreased,while high selectivity could be obtained at low pyrolytic *** a trend was also observed as the AC-to-WS ratio continuously *** alkylphenols production achieved a maximal yield of 44.19 mg/g with the corresponding selectivity of 34.7%at the pyrolytic temperature of 400℃and AC-to-WS ratio of 3,compared with those of only 4.67 mg/g and 6.1%without *** addition,the possible formation mechanism of alkylphenols was also proposed with the catalysis of N/WSAC.

关键词： Pyrolysis Walnut shell Alkylphenols Nitrogen-doped activated carbon

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A review of earthquake occurrences and observations in Nigeria

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Earthquake Science 2010年第3期23卷 289-294页

作者： Ofonime Umo Akpan tahir Abubakar Yakubu Centre for Geodesy and Geodynamics

Although Nigeria is not located within the major seismic zones of the world; over the years,several minor earthquakes have been experienced in some parts of the *** first widely reported occurrence of an Earth tremor in Nigeria was in *** events were reported in 1939,1964,1984,1990,1994,1997,2000 and *** intensities of these events ranged from III to VI based on the Modified Mercalli Intensity *** these events,only the 1984,1990,1994 and 2000 events were instrumentally *** had body wave magnitudes ranging from 4.3 to 4.5,local magnitudes between 3.7 and 4.2,and surface wave magnitudes of 3.7 to *** these events occurred,there were no functional seismological observatories in ***,that has now changed with the establishment of a seismographic network managed by the Centre for Geodesy and Geodynamics（CGG）,Toro,***,the network has four operational stations equipped with 24-bit 4-channel recorders and broadband 30-second *** are being made to establish more stations and migrate to real-time collection of seismic data using the general packet radio service（GPRS） technology as well as automatic location of *** sensing,geological and geophysical studies have revealed the presence of a NNE-SSW trending Ifewara-Zungeru fault zone which has been shown to be linked with the Atlantic fracture *** dynamics of the Atlantic fracture zones have been suggested to be responsible for the seismic activities experienced in the areas.

关键词： Nigeria seismic activity seismological observatories Ifewara-Zungeru fault zone

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A broadband cross-polarization conversion anisotropic metasurface based on multiple plasmon resonances

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Chinese Physics B 2018年第1期27卷 357-364页

作者： M Ismail Khan Farooq A tahir Research Institute for Microwave and Millimeter-wave Studies (RIMMS) National University of Sciences and Technology (NUST) Department of Electrical Engineering COMSATS Institute of Information Technology Attock Campus

A compact broadband cross-polarization conversion metasurface functioning in the microwave regime is realized and experimentally demonstrated. The metasurface consists of a two-dimensional periodic arrangement of anisotropic double- slit split-ring-resonator-based unit cells printed on top of a dielectric substrate, backed by metallic cladding. The proposed metasurface converts an x- or y-polarized wave into its orthogonal polarization over a fractional bandwidth of 100% from 5- 15 GHz, both for normal as well as oblique incidence. Moreover, the sub-wavelength unit-cell size, thin dielectric substrate, and unique unit-cell design collectively make the response of the metasurface same for both polarizations and insensitive to the incidence angle. The designed structure is fabricated and tested. The measurement and simulation results are found to be consistent with each other.

关键词： cross-polarization conversion anisotropy metasurface plasmon resonances

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Raw mix designing,clinkerization and manufacturing of high-strength Portland cement from the limestone and clay of Darukhula Nizampur,Nowshera District,North-West Frontier Province (N.W.F.P.),Pakistan

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Chinese Journal Of Geochemistry 2009年第3期28卷 279-283页

作者： Noor-ul-Amin tahir Shah Khurshid Ali Institute of Chemical Science University of PeshawarPakistan National Center of Excellence in Geology University of PeshawarPakistan

This paper covers the detailed version of the potential raw material deposits at Darukhula and the adjacent areas of Nizampur, the manufacturing of high-strength Portland cement samples from the same material and comparison of the physical and chemical parameters for resulting cement with British and Pakistan standard specifications, which include compressive strength, setting time, consistency, lechatelier expansion, Blaine and insoluble residue. It was found that the raw material available in the study area meets the standard specifications and the area is feasible for the cement plant installation. The area can provide raw material which is quite sufficient for the running of a cement plant.

关键词：水泥制造业巴基斯坦硅酸盐高强度石灰石设计生料边境

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Effects of fasting and preoperative feeding in children

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World Journal of Gastroenterology 2009年第39期15卷 4919-4922页

作者： Muslim Yurtcu Engin Gunel tahir Kemal Sahin Abdullah Sivrikaya Department of Pediatric Surgery Meram Medical School of Selcuk University Department of Public Health Meram Medical School of Selcuk University Department of Biochemistry Meram Medical School of Selcuk University

AIM： To investigate whether children should undergo surgery without a long period of fasting after feeding. METHODS： Eighty children with inguinoscrotal disorders （aged 1-10 years） were studied prospectively. They were divided into eight groups that each contained 10 children who were fed normal liquid food （NLF） and a high-calorie diet （HCD） 2, 3, 4 and 5 h before surgery, in two doses at 6-h intervals. NLF was given to four groups and HCD to the other four. In all groups, glucose, prealbumin and cortisol levels in the blood were measured twice： just after oral feeding and just before the operation. After the establishment of adequate anesthesia, gastric residue liquid was measured with a syringe. RESULTS： Blood glucose levels in all patients fed NLF and HCD were high, except in patients inthe HCD-4 group. There was no significant difference in the blood prealbumin levels. There was a significant increase in the blood cortisol levels in the NLF-2 （14.4± 5.7）, HCD-2 （13.2 ± 6.0）, NLF-3 （10.9± 6.4）, and HCD-5 （6.8 ± 5.7） groups （P 〈 0.05）. CONCLUSION： The stress of surgery may be tolerated by children when they are fed up to 2 h before elective *** words： Cortisol; Diet; Fasting; Food; Glucose; Liquids; Prealbumin

关键词： Cortisol Diet Fasting Food Glucose Liquids Prealbumin

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Analysis of Heat Transport in a Powell-Eyring Fluid with Radiation and Joule Heating Effects via a Similarity Transformation

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Fluid Dynamics & Materials Processing 2023年第3期19卷 663-677页

作者： tahir Naseem Iqra Bibi Azeem Shahzad Mohammad Munir Department of Mathematics Government Postgraduate College Haripur22620Pakistan Basic Sciences Department University of Engineering and TechnologyTaxila47050Pakistan Department of Mathematics Government Postgraduate CollegeAbbottabad22010Pakistan

Heat transfer in an Eyring-Powell fluid that conducts electricity and flows past an exponentially growing sheet is *** the sheet is stretched in the x direction,the flow develops in the region with y>*** problem is tackled through a set of partial differential equations accounting for Magnetohydrodynamics(MHD),radiation and Joule heating effects,which are converted into a set of equivalent ordinary differential equations through a similarity *** converted problem is solved in MATLAB in the framework a fourth order accurate integration *** is found that the thermal relaxation period is inversely proportional to the thickness of the thermal boundary layer,whereas the Eckert-number displays the opposite *** this characteristic number grows,the temperature within the channel increases.

关键词： Stretched flow powell-eyring model heat flux model radiated effect relaxation phenomenon numerical study

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Bioconvection Cross Diffusion Effects on MHD Flow of Nanofluids over Three Different Geometries with Melting

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Computer Modeling in Engineering & Sciences 2022年第5期131卷 1023-1039页

作者： tahir Kamran Muhammad Imran Muhammad N.Naeem Mohsan Raza Department of Mathematics Government College University FaisalabadFaisalabad38000Pakistan

Currently,nanofluid is a hot area of interest for *** nanofluid with bioconvection phenomenon attracted the researchers owing to its numerous applications in the field of nanotechnology,microbiology,nuclear science,heat storage devices,biosensors,biotechnology,hydrogen bomb,engine of motors,cancer treatment,the atomic reactor,cooling of devices,and in many *** article presents the bioconvection cross-diffusion effects on the magnetohydrodynamic flow of nanofluids on three different geometries(cone,wedge,and plate)with mixed *** temperature-dependent thermal conductivity,thermal diffusivity,and Arrhenius activation energy applications are considered on the fluid flow with melting *** flow is analyzed under thermal and solutal Robin’s *** problem is formulated in the mathematical formulation of partial differential equations(PDEs).The similarity transformations are applied to diminish the governing nonlinear coupled boundary value problems into higher-order non-linear ordinary differential equations(ODEs).The resulting expressions/equation numerically tackled utilizing the famous bvp4c package by MATLAB for various interesting *** results were physically and numerically calculated through graphics and tables for the velocity field,energy distribution,nanoparticles concentration,and microorganisms profile for numerous *** the obtained results,we discern that the transfer of heat and mass coefficient is high over a plate and cone in the flow,*** velocity profile is reduced via a larger magnetic *** thermal conductivity enhances the thermal *** thermophoresis enhanced the concentration of *** microorganisms’Biot number boosts the microorganism’s profile.

关键词： MHD nano-fluids bioconvection heat flux MATLAB

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Characterization and anticancer potential of Withania somnifera fruit bioactives(a native species to Pakistan)using gas chromatography-mass spectrometer,nuclear magnetic resonance and liquid chromatography-mass spectrometry-electrospray ionization

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Journal of Traditional Chinese Medicine 2022年第6期42卷 908-914页

作者： Qudsia Tabassam tahir Mehmood Sibtain Ahmed Farooq Anwar Abdul Rauf Raza Institute of Chemistry University of SargodhaSargodha-40100Pakistan Institute of Biochemistry and Biotechnology University of Veterinary and Animal Sciences-UVAS54000-Lahore.Pakistan University of California San Diego 9500 Gilman Drive La JollaCA 92093USA

INTRODUCTION:Withania somnifera(***)is a plant with remarkable pharmacological *** plant has an impressive profile of medicinal uses in the folk medicine system of several ***:This comprehensive study is aimed to characterize phytochemicals in fruit of *** and tested for in vitro anticancer potential to find out active candidate in disease prevention and ***:The bioactive components from *** fruit were extracted with polar and non-polar *** potential of the isolated bioactive was assessed against different cancer cell lines through MTT assay and Incucytes imaging *** extracts were characterized for secondary metabolites using GCMS(gas chromatography-mass spectrometer),LCMS(liquid(electrospray Ionization)and 1H-NMR(electrospray Ionization)***:Both freeze-dried and rotary evaporator condensed extracts exhibited anticancer potential against MDA-MB-231,MCF7-SKOV3 and SKBR3 cell *** tested extracts have cell growth inhibition potential against mammalian cancer cell *** acid purified from n-hexane extract through HPLC was investigated for its cytotoxicity against breast cancer cell line SKBR3 by using Incucytes imaging ***:We found that a variety of bioactive compounds existed in this *** identified compound that was not investigated for cytotoxicity in previous studies was purified and its application showed cytotoxicity on breast cancer cell lines.A number of bioactive identified from *** fruit may have an effective potential for development into chemotherapy drugs.

关键词： phytochemicals plants medicinal anti-cancer activities purification state-of-the-art techniques

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Characterization of ion irradiated silicon surfaces ablated by laser-induced breakdown spectroscopy

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Chinese Physics B 2018年第8期27卷 505-510页

作者： T Iqbal M Abrar M B tahir M Seemab A Majid S Rafique Department of Physics Faculty of Sciences University of Gujrat Hafiz Hayat Campus Department of Physics Hazara University Mansehra Department of Physics University of Engineering and Technology (UET)Lahore Pakistan

Low energy metallic ions, generated by a Q-switched Nd：YAG laser （1064-nm wavelength, 10-mJ energy, 9-nm 12-ns-pulse width, 1011 W/cm2 intensity） irradiated on a silicon substrate to modify various properties, such as electrical, morphological, and structural modifications. Thomson parabola technique is used to calculate the energy of these metallic ions whereas the electrical conductivity is calculated with the help of Four-point probe. Interestingly circular tracks forming chain like damage trails are produced via these energetic ions which are carefully examined by optical microscopy. It is observed that excitation, ionization, and cascade collisions are responsible for surface modifications of irradiated samples. Four-point probe analysis revealed that the electrical conductivity of substrate has reduced with increasing trend of atomic number of irradiated metallic ions （A1, Ti, Cu, and Au）. The x-ray diffraction analysis elucidated the crystallographic changes leading to reduction of grain size of N-type silicon substrate, which is also associated with the metallic ions used. The decreasing trend of conductivity and grain size is due to thermal stresses, scattering effect, structural imperfections, and non-uniform conduction of energy absorbed by substrate atoms after the ion irradiation.

关键词： ablation Thomson parabola technique four-point probe

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