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First Principles Calculations for Corrosion in Mg-Li-Al Alloys with Focus on Corrosion Resistance: A Comprehensive Review
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作者 muhammad Abdullah Khan muhammad usman Yuhong Zhao 《Computers, Materials & Continua》 SCIE EI 2024年第11期1905-1952,共48页
This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-pri... This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-principles calculations based on Density Functional Theory(DFT)and the quasi-harmonic approximation(QHA),the combined properties of the Mg-Li-Al phase are explored,revealing superior incompressibility,shear resistance,and stiffness compared to individual elements.The review highlights the brittleness of the alloy,supported by B/G ratios,Cauchy pressures,and Poisson’s ratios.Electronic structure analysis shows metallic behavior with varied covalent bonding characteristics,while Mulliken population analysis emphasizes significant electron transfer within the alloy.This paper also studied thermodynamic properties,including Debye temperature,heat capacity,enthalpy,free energy,and entropy,which are precisely examined,highlighting the Mg-Li-Al phase sensitive to thermal conductivity and thermal performance potential.Phonon density of states(PHDOS)confirms dynamic stability,while anisotropic sound velocities reveal elastic anisotropies.This comprehensive review not only consolidates the current understanding of the Mg-Li-Al alloy’s properties but also proposes innovative strategies for enhancing corrosion resistance.Among these strategies is the introduction of a corrosion barrier akin to the Mg-Li-Al network,which holds promise for advancing both the applications and performance of these alloys.This review serves as a crucial foundation for future research aimed at optimizing alloy design and processing methods. 展开更多
关键词 First-principles calculations Mg-Li-Al alloys corrosion resistance thermodynamic properties mechanical properties
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耳后皮肤扩张行小耳畸形耳再造(英文) 被引量:3
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作者 muhammad usman 王继华 +3 位作者 YADAV SVKENDRA PARSAD 汤婷 张颖佳 杨蔚琪 《昆明医科大学学报》 CAS 2017年第4期88-92,共5页
目的探讨耳后皮肤扩张法施行耳再造的效果.方法通过耳后皮肤埋置扩张器,注水扩张,第二期切取肋软骨制作耳支架,用扩张的皮瓣包裹,持续负压吸引耳廓成型,三期手术时进行耳垂转位,加深外耳道,完成耳廓再造.结果用该方法完成小耳畸形耳廓... 目的探讨耳后皮肤扩张法施行耳再造的效果.方法通过耳后皮肤埋置扩张器,注水扩张,第二期切取肋软骨制作耳支架,用扩张的皮瓣包裹,持续负压吸引耳廓成型,三期手术时进行耳垂转位,加深外耳道,完成耳廓再造.结果用该方法完成小耳畸形耳廓再55例,随访6个月至2 a,除有5例出现扩张器外露、感染及耳软骨外露效果不佳外,除50例效果满意,再造的耳廓位置、大小、角度、外形与对侧耳廓基本对称.结论耳后皮肤扩张的方法可有效解决耳造皮肤不足的问题. 展开更多
关键词 小耳畸形 扩张术 自体肋软骨 耳再造
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Automatic Detection of Outliers in Multi-Channel EMG Signals Using MFCC and SVM
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作者 muhammad Irfan Khalil Ullah +6 位作者 Fazal muhammad Salman Khan Faisal Althobiani muhammad usman Mohammed Alshareef Shadi Alghaffari Saifur Rahman 《Intelligent Automation & Soft Computing》 SCIE 2023年第4期169-181,共13页
The automatic detection of noisy channels in surface Electromyogram(sEMG)signals,at the time of recording,is very critical in making a noise-free EMG dataset.If an EMG signal contaminated by high-level noise is record... The automatic detection of noisy channels in surface Electromyogram(sEMG)signals,at the time of recording,is very critical in making a noise-free EMG dataset.If an EMG signal contaminated by high-level noise is recorded,then it will be useless and can’t be used for any healthcare application.In this research work,a new machine learning-based paradigm is proposed to automate the detection of low-level and high-level noises occurring in different channels of high density and multi-channel sEMG signals.A modified version of mel fre-quency cepstral coefficients(mMFCC)is proposed for the extraction of features from sEMG channels along with other statistical parameters i-e complexity coef-ficient,hurst exponent,and root mean square.Several state-of-the-art classifiers such as Support Vector Machine(SVM),Ensemble Bagged Trees,Ensemble Sub-space Discriminant,and Logistic Regression are used to automatically identify an EMG channel either bad or good based on these extracted features.Comparison-based analyses of these classifiers have also been considered based on total classi-fication accuracy,prediction speed(observations/sec),and processing time.The proposed method is tested on 320 simulated EMG channels as well as 640 experi-mental EMG channels.SVM is used as our main classifier for the detection of noisy channels which gives a total classification accuracy of 99.4%for simulated EMG channels whereas accuracy of 98.9%is achieved for experimental EMG channels. 展开更多
关键词 Machine learning surface electromyography support vector machine classification features
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第七肋软骨移植矫治鞍鼻畸形(英文)
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作者 YADAV Surendra Parsad 王继华 +3 位作者 汪虹 muhammad usman 张景波 张伯俊 《昆明医科大学学报》 CAS 2017年第5期109-115,共7页
目的评估肋软骨移植矫正鞍鼻畸形的效果和安全性.方法 2013年1月至2016年12月间32例鞍鼻畸形(10例男性,22例女性)平均年龄在25岁(12~30岁)进行了7肋软骨移植矫正鞍鼻畸形;14例为创伤后鼻畸形,10例为鼻畸形,8例为唇裂继鞍鼻畸形.通过肋... 目的评估肋软骨移植矫正鞍鼻畸形的效果和安全性.方法 2013年1月至2016年12月间32例鞍鼻畸形(10例男性,22例女性)平均年龄在25岁(12~30岁)进行了7肋软骨移植矫正鞍鼻畸形;14例为创伤后鼻畸形,10例为鼻畸形,8例为唇裂继鞍鼻畸形.通过肋软骨移植后效果,供区瘢痕等并发症观察,对肋软骨移植隆鼻可行性进行评估.结果平均切取肋软骨时间为30 min,肋软骨长度为4 cm术后3例出现偏斜,1例感染,1例出现固定钢针外露,2例出现胸部瘢痕增生;其余病例对手术效果满意.结论第7肋软骨容易切取,操作简单,是矫治重度鞍鼻畸形的理想移植物. 展开更多
关键词 自体肋软骨 鼻整形 鞍鼻 移植
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Spatiotemporal Monitoring for Deforestation and Forest Degradation Activities in Selected Areas of Khyber Pakhtunkhwa (KPK)
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作者 Saif ur Rehman Khalid Mobushir Riaz Khan +2 位作者 muhammad usman muhammad Waqar Yasin muhammad Shahid Iqbal 《International Journal of Geosciences》 2016年第10期1191-1207,共17页
The global significance of forest ecosystems requires precise determination of the amount of carbon stored in different forest ecosystems. Regular monitoring of forests can aid in designing efficient climate change co... The global significance of forest ecosystems requires precise determination of the amount of carbon stored in different forest ecosystems. Regular monitoring of forests can aid in designing efficient climate change control strategies at national and global scale specially in reducing emissions from deforestation and degradation strategies. This research is designed to focus on determining deforestation of study area from 2001 to 2011 using Remote Sensing (RS) and Geographic Information System (GIS) techniques. This research provided rate and amount of degradation of forests in the study area and was quite helpful in formulating a strategy to earn carbon credits consistently and, therefore, will help in the uplifting of the standards of local population. 展开更多
关键词 DEFORESTATION DEGRADATION Carbon Credits Climate Change
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Effect of Nitrogen on Yield and Oil Quality of Sunflower (<i>Helianthus Annuus</i>L.) Hybrids under Sub Humid Conditions of Pakistan 被引量:9
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作者 Wajid Nasim Ashfaq Ahmad +7 位作者 Asghari Bano Rabiu Olatinwo muhammad usman Tasneem Khaliq Aftab Wajid Hafiz Mohkum Hammad muhammad Mubeen Muzzammil Hussain 《American Journal of Plant Sciences》 2012年第2期243-251,共9页
Sunflower (Helianthus annuus L.) has emerged as an economically important crop in Pakistan due to its significant share in vegetable oil production. The plant metabolic processes require protein to increase the vegeta... Sunflower (Helianthus annuus L.) has emerged as an economically important crop in Pakistan due to its significant share in vegetable oil production. The plant metabolic processes require protein to increase the vegetative, reproductive growth and yield of the crop. The protein is wholly dependent upon the amount of nitrogen fertilization available for plant use. A two-year field study was conducted in 2008 and 2009. The objective was to determine the effect of different nitrogen (N) levels (N1 = 0 kg·ha–1, N2 = 60 kg·ha–1, N3 = 120 kg·ha–1, N4 = 180 kg·ha–1 and N5 = 240 kg·ha–1) on three sunflower hybrids (Hysun-33, Hysun-38 and Poineer-64A93) in agro-climatic conditions of Gujranwala, a sub-humid region in the centre of the Punjab province of Pakistan. A randomized complete block design split plot experiment was set-up with cultivars in the main plots and N levels in the subplots. Results showed that Hysun-38 gave maximum TDM (15815 kg·ha–1) and maximum grain yield (3389 kg·ha–1), while minimum TDM (14640 kg·ha–1) and grain yield (3125 kg·ha–1) was observed in Hysun-33. Among different N rates evaluated, N4 gave maximum TDM (17890 kg·ha–1) and grain yield (3809 kg·ha–1) compared to the other N rates. The maximum oil content (46.2%) was observed in Hysun-38 without application of N fertilizer (N1), while the minimum oil content (40.6%) was observed from N5 treatment. In conclusion, the application of 180 kg·ha–1 N to Hysun-38 provided the best combination for good yield in sunflower crop under the prevailing sub-humid conditions of Pakistan. 展开更多
关键词 HELIANTHUS annuus L. NITROGEN Rates YIELD Subhumid Conditions Pakistan
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Perovskite-type lanthanum ferrite based photocatalysts:Preparation,properties,and applications 被引量:4
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作者 muhammad Humayun Habib Ullah +4 位作者 muhammad usman Aziz Habibi-Yangjeh Asif Ali Tahir Chundong Wang Wei Luo 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第3期314-338,I0009,共26页
Clean energy and a sustainable environment are grand challenges that the world is facing which can be addressed by converting solar energy into transportable and storable fuels(chemical fuel).The main scientific and t... Clean energy and a sustainable environment are grand challenges that the world is facing which can be addressed by converting solar energy into transportable and storable fuels(chemical fuel).The main scientific and technological challenges for efficient solar energy conversion,energy storage,and environmental applications are the stability,durability,and performance of low-cost functional materials.Among different nanomaterials,perovskite type LaFeO_(3)has been extensively investigated as a photocatalyst due to its abundance,high stability,compositional and structural fexibility,high electrocatalytic activity,efficient sunlight absorption,and tunable band gap and band edges.Hence,it is urgent to write a comprehensive review to highlight the trend,challenges,and prospects of LaFeO_(3)in the field of photocatalytic solar energy conversion and environment purification.This critical review summarizes the history and basic principles of photocatalysis.Further,it reviews in detail the LaFeO_(3),applications,shortcomings,and activity enhancement strategies including the design of nanostructures,elemental doping,and heterojunctions construction such as Type-I,Type-II,Z-Type,and uncommon heterojunctions.Besides,the optical and electronic properties,charge carriers separation,electron transport phenomenon and alignment of the band gaps in LaFeO_(3)-based heterostructures are comprehensively discussed. 展开更多
关键词 Perovskite-type LaFeO_(3) Solar fuel PHOTOCATALYSIS Doping HETEROSTRUCTURES
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Unfolding the structural features of NASICON materials for sodium-ion full cells 被引量:4
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作者 muhammad Tayyab Ahsan Zeeshan Ali +1 位作者 muhammad usman Yanglong Hou 《Carbon Energy》 SCIE CAS 2022年第5期776-819,共44页
Sodium-ion batteries(SIBs)are potential candidates for the replacement of lithium-ion batteries to meet the increasing demands of electrical storage systems due to the low cost and high abundance of sodium.Sodium supe... Sodium-ion batteries(SIBs)are potential candidates for the replacement of lithium-ion batteries to meet the increasing demands of electrical storage systems due to the low cost and high abundance of sodium.Sodium superionic conductor(NASICON)structured materials have attracted enormous interest in recent years as electrode materials for safer and long-term performance of SIBs for electric energy storage smart grids.These materials have a threedimensional robust framework,high redox potential,thermal stability,and a fast Na^(+)-ion diffusion mechanism.However,NASICON has low intrinsic electronic conductivity,which limits the electrochemical performance.This review describes the structural features of NASICONs to illustrate the ion storage mechanism and electrochemical performance of SIBs.Details of the NASICON crystal structure,the affiliated Na^(+)-ion diffusion mechanism,morphology,and electrochemical performance of these materials in sodiumion half-cells as well as full cells are described.In addition to the application as electrode materials,the use of NASICONs as solid electrolytes is also elaborated in solid-state SIBs.Based on these aspects,we have provided more perspectives in terms of the commercialization of SIBs and strategies to overcome the limitations of NASICONs.Hence,this review is expected to provide the researchers of energy storage with an in-depth understanding of NASICON materials with the knowledge of structural features,which will provide a new avenue on the practicality of SIBs. 展开更多
关键词 cathode materials electrical storage systems full cells NASICON materials sodium-ion batteries
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Simultaneous operation of dibenzothiophene hydrodesulfurization and methanol reforming reactions over Pd promoted alumina based catalysts 被引量:3
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作者 muhammad Yaseen muhammad Shakimllah +4 位作者 Imtiaz Ahmad Ata Ur Rahman Faiz Ur Rahman muhammad usman Rauf Razzaq 《燃料化学学报》 EI CAS CSCD 北大核心 2012年第6期714-720,共7页
In the current study simultaneous reactions of hydrodesulfurization(HDS) of dibenzothiophene(DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic(Co-Mo/Al2O3 and Ni-Mo/Al2O3) and t... In the current study simultaneous reactions of hydrodesulfurization(HDS) of dibenzothiophene(DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic(Co-Mo/Al2O3 and Ni-Mo/Al2O3) and tri-metallic(Pd-Co-Mo/Al2O3 and Pd-Ni-Mo/Al2O3) catalyst systems which were prepared by incipient impregnation method.In situ hydrogen utilization and low Pd loadings were the major targets of this study.For comparison purpose,catalytic activity was separately determined for both the methanol reforming and HDS of DBT reactions as well.Ni based catalysts were confirmed with better activity than Co ones for both the reactions with Pd promoted ones ranking at the top i.e.Pd-Ni-Mo/Al2O3 > Ni-Mo/Al2O3 > Pd-Co-Mo/Al2O3 > Co-Mo/Al2O3 where Pd-Ni-Mo/Al2O3 showed 91% DBT conversion at 380 ℃ and 12 h reaction time.Some of the selected organic additives on catalytic activity were tested for their effect toward HDS reaction which was unique with close relation to their chemical nature.Reaction products were quantitatively and qualitatively analyzed via HPLC and GC-MS techniques respectively which helped in elucidating reaction mechanism. 展开更多
关键词 加氢脱硫 二苯并噻吩 催化剂 高效液相色谱法
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Growth of Carbon Nanocoils by Porous α-Fe2O3/SnO2 Catalyst and Its Buckypaper for High Efficient Adsorption 被引量:3
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作者 Yongpeng Zhao Jianzhen Wang +7 位作者 Hui Huang Tianze Cong Shuaitao Yang Huan Chen Jiaqi Qin muhammad usman Zeng Fan Lujun Pan 《Nano-Micro Letters》 SCIE EI CAS CSCD 2020年第2期137-153,共17页
High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicati... High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications. 展开更多
关键词 Carbon nanocoils Porousα-Fe2O3/SnO2 CATALYST BUCKYPAPER Methylene blue adsorption
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Modelling of a tubular membrane contactor for pre-combustion CO_2 capture using ionic liquids:Influence of the membrane configuration, absorbent properties and operation parameters 被引量:3
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作者 Zhongde Dai muhammad usman +1 位作者 Magne Hillestad Liyuan Deng 《Green Energy & Environment》 SCIE 2016年第3期266-275,共10页
A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehen... A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehensive two-dimensional(2 D) mass-transfer model was developed based on finite element method. The effects of liquid properties, membrane configurations, as well as operation parameters on the CO_2 removal efficiency were systematically studied. The simulation results show that CO_2 can be effectively removed in this process. In addition, it is found that the liquid phase mass transfer dominated the overall mass transfer. Membranes with high porosity and small thickness could apparently reduce the membrane resistance and thus increase the separation efficiency. On the other hand, the membrane diameter and membrane length have a relatively small influence on separation performance within the operation range. 展开更多
关键词 CO2 capture Pre-combustion Membrane contactor Ionic liquids MODELLING
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Foliar Application of Phosphorus Enhances Photosynthesis and Biochemical Characteristics of Maize under Drought Stress 被引量:2
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作者 Zahoor Ahmad Ejaz Ahmad Waraich +8 位作者 muhammad Zia ur Rehman muhammad Ashar Ayub muhammad usman Hesham Alharby Atif Bamagoos Celaleddin Barutçular muhammad Ali Raza FatihÇiğ Ayman El Sabagh 《Phyton-International Journal of Experimental Botany》 SCIE 2021年第2期503-514,共12页
Water is essential for the growth period of crops;however,water unavailability badly affects the growth and physiological attributes of crops,which considerably reduced the yield and yield components in crops.Therefor... Water is essential for the growth period of crops;however,water unavailability badly affects the growth and physiological attributes of crops,which considerably reduced the yield and yield components in crops.Therefore,a pot experiment was conducted to investigate the effect of foliar phosphorus(P)on morphological,gas exchange,biochemical traits,and phosphorus use efficiency(PUE)of maize(Zea mays L.)hybrids grown under normal as well as water deficit situations at the Department of Agronomy,University of Agriculture Faisalabad,Pakistan in 2014.Two different treatments(control and P@8 kg ha^(−1))and four hybrids(Hycorn,31P41,65625,and 32B33)of maize were tested by using a randomized complete block design(RCBD)with three replications.Results showed that the water stress caused a remarkable decline in total soluble protein(9.7%),photosynthetic rate(9.4%)and transpiration rate(13.4%),stomatal conductance(10.2%),and internal CO_(2)rate(20.4%)comparative to well-watered control.An increase of 37.1%,36.8%,and 24.5%were recorded for proline,total soluble sugar,and total free amino acid,respectively.However,foliar P application minimized the negative impact of drought by improving plant growth,physio-biochemical attributes,and PUE in maize plants under water stress conditions.Among the hybrids tested,the hybrid 6525 performed better both under stress and non-stress conditions.These outcomes confirmed that the exogenous application of P improved drought stress tolerance by modulating growth,physio-biochemical attributes,and PUE of maize hybrids. 展开更多
关键词 Photosynthetic attributes biochemical characters water stress foliar P MAIZE
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Qualitative and semi-quantitative analysis of health-care pharmaceutical products using laser-induced breakdown spectroscopy 被引量:1
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作者 Sobia Nisar Ghulam Dastgeer +1 位作者 muhammad Shafiq muhammad usman 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2019年第1期20-24,共5页
Laser-induced breakdown spectroscopy(LIBS) is a sensitive optical technique that is capable of rapid multi-elemental analysis. The development of this technique for elemental analysis of pharmaceutical products may ev... Laser-induced breakdown spectroscopy(LIBS) is a sensitive optical technique that is capable of rapid multi-elemental analysis. The development of this technique for elemental analysis of pharmaceutical products may eventually revolutionize the field of human health. Under normal circumstances, the elemental analysis of pharmaceutical products based on chemical methods is time-consuming and complicated. In this investigation, the principal aim is to develop an LIBS-based methodology for elemental analysis of pharmaceutical products. This LIBS technique was utilized for qualitative as well as quantitative analysis of the elements present in Ca-based tablets. All the elements present in the tablets were detected and their percentage compositions were verified in a single shot, using the proposed instrument. These elements(e.g., Ca, Mg, Fe, Zn, and others) were identified by the wavelengths of their spectral lines, which were verified using the NIST database. The approximate amount of each element was determined based on their observed peaks and the result was in exact agreement with the content specification. The determination of the composition of prescription drug for patients is highly important in numerous circumstances. For example, the exploitation of LIBS may facilitate elemental decomposition of medicines to determine the accuracy of the stated composition information. Moreover, the approach can provide element-specific, meaningful, and accurate information related to pharmaceutical products. 展开更多
关键词 LASER-INDUCED BREAKDOWN spectroscopy Elements identification HEALTH-CARE PHARMACEUTICS Qualitative ANALYSIS QUANTITATIVE ANALYSIS
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3-D seismic interpretation of stratigraphic and structural features in the Upper Jurassic to Lower Cretaceous sequence of the Gullfaks Field,Norwegian North Sea:A case study of reservoir development 被引量:3
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作者 muhammad usman Numair Ahmed Siddiqui +3 位作者 Eduardo Garzanti muhammad Jamil Qazi Sohail Imran Luqman Ahmed 《Energy Geoscience》 2021年第4期287-297,共11页
The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods f... The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods for fractures are based on the theory of effective anisotropy medium.The aim of this work is to improve the structural images with dense sampling of 3-D survey to evaluate structural and stratigraphic models for reservoir development to predict reservoir quality.The present study of the Gullfaks Field,located in the Norwegian North Sea Gullfaks sector,identifies the shallowest structural elements.The steepness of westward structural dip decreases eastward during the Upper Jurassic to Lower Cretaceous deposition.Reservoir sands consist of the Middle Jurassic deltaic deposits and Lower Jurassic fluvial channel and delta plain deposits.Sediment supply steadily prevails on sea-level rise and the succession displays a regressive trend indicated by a good continuous stacking pattern.The key factor for the development of reservoirs in the Gullfaks Field is fault transmissibility with spatially distributed pressure.The majority of mapped faults with sand-to-sand contacts are non-sealing,which provide restriction for the HC flow between the fault blocks.The traps for HC accumulation occur between the post-rift and syn-rift strata,i.e.antiform set by extensional system,unconformity trap at the top of syndeposition,and structural trap due to normal faults.Overall reservoir quality in the studied area is generally excellent with average 35%porosity and permeability in the Darcy range.Our findings are useful to better understand the development of siliciclastic reservoirs in similar geological settings worldwide. 展开更多
关键词 3-D seismic model Mesozoic stratigraphic boundary Structural trap Reservoir quality Gullfaks Field
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Study on the synthesis of spin labeled poly(styrene-co-maleic acid)s and their segmental motion 被引量:1
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作者 Kaleem-Ur-Rahman Naveed Li Wang +9 位作者 Haojie Yu Qian Zhang Wei Xiong Raja Summe Ullah Ahsan Nazir muhammad usman Shah Fahad Amin Khan Md Alim Uddin Di Shen 《Magnetic Resonance Letters》 2022年第2期80-90,I0002,共12页
Study of the segmental mobility of polymer chains is important when the polymer is used as drag reduction agents of crude oil.Electron spin resonance(ESR)spectroscopy can provide important information about segmental ... Study of the segmental mobility of polymer chains is important when the polymer is used as drag reduction agents of crude oil.Electron spin resonance(ESR)spectroscopy can provide important information about segmental dynamics of polymer chains,which is related to their microenvironment.In this article,we employed an amphiphilic polymer to study the effect of hydrophilic/hydrophobic balance of the polymers on the segmental motion of polymer chains.Poly(styrene-co-maleic acid)(PSMA)was spin labeled with 4-amino TEMPO radicals by increasing the concentration of radical moiety on the polymer chains.The PSMA and spin labeled-PSMAs(SL-PSMAs)were characterized by nuclear magnetic resonance(NMR),Fourier transform infrared(FT-IR)spectroscopy,Cyclic voltammetry(CV)and ESR techniques.Inter-polymer complexes(IPCs)of SL-PSMA-2 were prepared by employing polyethylene glycols(PEGs)of varying molecular weights.The results showed that the increased hydrophobic interactions of nitroxide radicals on the SLPSMAs’chains reduced the rotational mobility of spin labels and the random coil-toglobular transition of polymer chains occurred at higher pH value for SL-PSMAs,which showed a slow motion component in the ESR spectra of SL-PSMAs.Further,by increasing the molecular weight of PEGs in IPCs the complexation was increased,which also reduced the rotational motion of spin labels due to interpolymer hydrogen bonding causing a slow motion component in the ESR spectra.©2021 The Authors. 展开更多
关键词 Electron spin resonance(ESR) Spin labeling Nitroxide radicals poly(styrene-co-maleic acid)s Segmental motion
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The charge state distribution of B, C, Si, Ni, Cu and Au ions on 5 MV pelletron accelerator
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作者 Ali Awais Javaid Hussain +5 位作者 muhammad usman Waheed Akram Kashif Shahzad Turab Ali Ishaq Ahmad Malik Maaza 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第5期43-47,共5页
Stripper gas and terminal potential play a key role for the charge state distribution in a tandem pelletron accelerator. The knowledge of this distribution is important for experiments performed on tandem accelerators... Stripper gas and terminal potential play a key role for the charge state distribution in a tandem pelletron accelerator. The knowledge of this distribution is important for experiments performed on tandem accelerators. The charge state distribution of B, C, Si, Ni, Cu and Au beams is measured by using Ar as stripper gas, and terminal potential is varied from 0.3 to 3.0 MV on 5UDH-2 tandem pelletron accelerator installed at the National Centre for Physics, Islamabad. The individual charge state is measured after the switching magnet at 15° in high-energy portion. It is observed that the higher charge states are stable in the range of lower and middle atomic masses of periodic table, whereas higher atomic mass(Au) shows beam current instability in higher charge states. For carbon,the charge distribution at 1.7 MV terminal potential by varying stripper gas pressure is also studied, which resulted in decreased overall transmission with good current value for higher charge states. 展开更多
关键词 Pelletron ACCELERATOR Charge state DISTRIBUTION STRIPPER gas TERMINAL potential
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Performance Evaluation of MWCNTs Reinforced Cement Mortar Composites using Natural and Commercial Surfactants
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作者 Qareeb Ullah Rao Arsalan Khushnood +3 位作者 Sajjad Ahmad muhammad usman Shad muhammad Jean-Marc Tulliani 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2022年第1期47-57,共11页
An efficient and promising approach for effectively dispersing multi-walled carbon nanotubes(MWCNTs)in cementitious composites has been investigated.The naturally occurring organic extracts from species of indigenousl... An efficient and promising approach for effectively dispersing multi-walled carbon nanotubes(MWCNTs)in cementitious composites has been investigated.The naturally occurring organic extracts from species of indigenously known‘Keekar’trees scattered along tropical and sub-tropical regions;is found as an exceptional replacement to the non-natural commercial surfactants.In the initial phase of investigation,ideal surfactant’s content required for efficient dispersion of MWCNTs in solution was determined using ultra-violet spectroscopy.The experimental investigations were then extended to five different cement composite formulations containing 0.0,0.025,0.05,0.08 and 0.10%MWCNTs by weight of cement.It was observed that the natural surfactant produced efficient dispersion at much reduced cost(approx.14%)compared with the commercial alternate.The estimated weight efficiency factor f was found 6.5 times higher for the proposed sustainable replacement to the conventional along with remarkable increase of 23%in modulus of rupture on 0.08 wt%addition of MWCNTs.Besides strength enhancement,the dispersed MWCNTs also improved the first crack and ultimate fracture toughness by 51.5%and 35.9%,respectively.The field emission scanning electron microscopy of the cryofractured samples revealed efficient dispersion of MWCNTs in the matrix leading to the phenomenon of effective crack bridging and crack branching in the composite matrix.Furthermore,the proposed scheme significantly reduced the early age volumetric shrinkage by 39%. 展开更多
关键词 MWCNTS acacia nilotica gum keekar triton X-100 FRACTURE crack bridging cement mortar early age micro-cracking SUSTAINABILITY
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3D geo-cellular static virtual outcrop model and its implications for reservoir petro-physical characteristics and heterogeneities
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作者 muhammad usman Numair A.Siddiqui +5 位作者 Shi-Qi Zhang Manoj J.Mathew Ya-Xuan Zhang muhammad Jamil Xue-Liang Liu Nisar Ahmed 《Petroleum Science》 SCIE CAS CSCD 2021年第5期1357-1369,共13页
Geostatistical data plays a vibrant role for surface-based reservoir modeling through outcrop analogues,which is used to understand three-dimensional(3D)variability of petrophysical properties.The main purpose of this... Geostatistical data plays a vibrant role for surface-based reservoir modeling through outcrop analogues,which is used to understand three-dimensional(3D)variability of petrophysical properties.The main purpose of this study is to improvise the surface-based 3D geo-modeling to demonstrate petrophysical characteristics and heterogeneities of Sandakan reservoirs,NW Borneo.We used point cloud data from Light Detection and Ranging(Li DAR)to build high-resolution virtual outcrop modeling(VOM)onto which we mapped 6 different lithofacies.Porosity and permeability of core plugs were measured to determine the average variance of petrophysical properties for each lithofacies.By utilizing the integration of VOMs analogues and petrophysical properties in Petrel^(TM),we demonstrated the distribution and associations of all lithofacies in pseudo wells that have inherent thin beds heterogeneities in 3D geocellular model.The results concluded that the heterogeneity of thin beds in lithofacies is dependent on porosity and permeability with input dataset.According to the final model,cross-bedding sandstone(CBS),hummocky cross-stratified sandstone(HCSS)and trough cross-bedding sandstone(TCBS)show good reservoir quality due to high porosity ranging from:25.6%to 20.4%and,19.3%-14.5%,and permeability ranging from:74.03 mD to 66.84 mD and,64.86 mD to 21.01 mD.In contrast,massive to weak laminae sandstone(MWLS)and bioturbated sandstone(BS)show fair to poor reservoir quality,caused baffling of surrounding mud sediments in the reservoir lithofacies.Results also revealed that Li DAR based VOM with petrophysical properties can significantly reduce the risk and minimize the cost of reservoir modeling in petroleum industry. 展开更多
关键词 Virtual outcrop modeling Lithofacies 3D geo-cellular model Petrophysical properties Reservoir heterogeneities
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Influences of Marangoni convection and variable magnetic field on hybrid nanofluid thin-film flow past a stretching surface
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作者 Noor Wali Khan Arshad Khan +3 位作者 muhammad usman Taza Gul Abir Mouldi Ameni Brahmia 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第6期494-501,共8页
Investigations on thin-film flow play a vital role in the field of optoelectronics and magnetic devices.Thin films are reasonably hard and thermally stable but quite fragile.The thermal stability of a thin film can be... Investigations on thin-film flow play a vital role in the field of optoelectronics and magnetic devices.Thin films are reasonably hard and thermally stable but quite fragile.The thermal stability of a thin film can be further improved by incorporating the effects of nanoparticles.In the current work,a stretchable surface is considered upon which hybrid nanofluid thin-film flow is taken into account.The idea of augmenting heat transmission by making use of a hybrid nanofluid is a focus of the current work.The flow is affected by variations in the viscous forces,along with viscous dissipation effects and Marangoni convection.A time-constrained magnetic field is applied in the normal direction to the flow system.The equations governing the flow system are shifted to a non-dimensional form by applying similarity variables.The homotopy analysis method is employed to find the solution to the resultant equations.It is noticed in this study that the flow characteristics decline with augmentation of magnetic,viscosity and unsteadiness parameters while they increase with enhanced values of thin-film parameters.Thermal characteristics are supported by increasing values of the Eckert number and the unsteadiness parameter and opposed by the viscosity parameter and Prandtl number.The numerical impact of different emerging parameters upon skin friction and the Nusselt number is calculated in tabular form.A comparison of current work with established results is carried out,with good agreement. 展开更多
关键词 thin-film flow hybrid nanofluid viscous dissipation stretching surface homotopy analysis method
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Smart Healthcare Using Data-Driven Prediction of Immunization Defaulters in Expanded Program on Immunization (EPI)
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作者 Sadaf Qazi muhammad usman +3 位作者 Azhar Mahmood Aaqif Afzaal Abbasi muhammad Attique Yunyoung Nam 《Computers, Materials & Continua》 SCIE EI 2021年第1期589-602,共14页
Immunization is a noteworthy and proven tool for eliminating lifethreating infectious diseases,child mortality and morbidity.Expanded Program on Immunization(EPI)is a nation-wide program in Pakistan to implement immun... Immunization is a noteworthy and proven tool for eliminating lifethreating infectious diseases,child mortality and morbidity.Expanded Program on Immunization(EPI)is a nation-wide program in Pakistan to implement immunization activities,however the coverage is quite low despite the accessibility of free vaccination.This study proposes a defaulter prediction model for accurate identification of defaulters.Our proposed framework classifies defaulters at five different stages:defaulter,partially high,partially medium,partially low,and unvaccinated to reinforce targeted interventions by accurately predicting children at high risk of defaulting from the immunization schedule.Different machine learning algorithms are applied on Pakistan Demographic and Health Survey(2017–18)dataset.Multilayer Perceptron yielded 98.5%accuracy for correctly identifying children who are likely to default from immunization series at different risk stages of being defaulter.In this paper,the proposed defaulters’prediction framework is a step forward towards a data-driven approach and provides a set of machine learning techniques to take advantage of predictive analytics.Hence,predictive analytics can reinforce immunization programs by expediting targeted action to reduce dropouts.Specially,the accurate predictions support targeted messages sent to at-risk parents’and caretakers’consumer devices(e.g.,smartphones)to maximize healthcare outcomes. 展开更多
关键词 Smart healthcare routine immunization predictive analytics defaulters VACCINATION machine learning targeted messaging
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