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MICELLAR PARAMETERS OF DIBLOCK COPOLYMERS AND THEIR INTERACTIONS WITH IONIC SURFACTANTS

Chinese Journal of Polymer Science 2012年第2期30卷 217-226页

作者： Noor rehman Abbas Khan Iram Bibi Mohammad Siddiq Department of Chemistry Quaid-I-Azam UniversityIslamabad 45320Pakistan Instituto de Quimica Universidade Federal do Rio Grande do SulUFRGS PO Box 15010CEP 91501-930Porto Alegre/RS/Brazil Department of Chemistry Abdul Wali Khan UniversityMardan K-PukhtoonkhwaPakistan

The interactions of non-ionic amphiphilic diblock copolymer poly（oxyethylene/oxybutylene）（E39B18） with anionic surfactant sodium dodecyl sulphate （SDS） and cationic surfactant hexadecyltrimethylammonium bromide （CTAB） were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration （CMC） and thereby the free energy of micellization （AGmic）, free energy of adsorption （AG^ds）, surface excess concentration （F） and minimum area per molecule （A）. Conductivity measurements were used to determine the critical micelle concentration （CMC）, critical aggregation concentration （CAC）, polymer saturation point （PSP）, degree of ionization （tr） and counter ion binding （l]）. Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks （11/Is） indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number （N）, number of binding sites （n） and free energy of binding （AGb） for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.

关键词： Surface tension Conductivity Dynamic light scattering steady-state fluorescence Micellization.

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Comparative study of heat transfer and pressure drop for curved-twisted tubes utilized in chemical engineering

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Chinese Journal of Chemical Engineering 2021年第12期34卷 53-64页

作者： Morteza Khoshvaght-Aliabadi Saber Deldar Shafiqur rehman Ashkan Alimoradi Department of Chemical Engineering Shahrood BranchIslamic Azad UniversityShahroodIran Department of Mechanical Engineering Tarbiat Modares UniversityTehranIran Center for Engineering Research The Research InstituteKing Fahd University of Petroleum and MineralsDhahran 31261Saudi Arabia Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityViet Nam

Increasing importance of heat transfer in chemical engineering science causes that investigation in the field of enhancement techniques is always one of the up-to-date topics for *** the current comparative analysis,the thermal enhancement and friction penalty are explored numerically for curved tubes via twisted *** accomplish this,three common geometries namely helical,serpentine,and Archimedes spiral,are considered at different coil-pitches and twist-pitches as well as five Reynolds numbers in the laminar flow *** results exhibit noticeable enhancements(up to 60%)in the thermal performance of the twisted cases as compared to the smooth *** highest increases are recorded for the serpentine case,followed by the helical and spiral *** is found that these enhancements vary via coil-pitch and *** coil-pitch and twist-pitch augments both heat transfer coefficient and pressure drop in all curved-twisted tubes,however,the effects of twist-pitch are more *** predict Nusselt number and friction factor,new correlations are also *** maximum deviations of the predicted results compared to the simulated data are within±5%.

关键词： Computational fluid dynamics Heat transfer Laminar flow Curved-twisted tubes Comparative study

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Securing Cloud Storage by Remote Data Integrity Check with Secured Key Generation

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Chinese Journal of Electronics 2021年第3期30卷 489-499页

作者： Abdul rehman LIU Jian Muhammad Qasim Yasin LI Keqiu College of Intelligence and Computing Tianjin University Tianjin Key Laboratory of Advance Networking National University of Modern Languages Faisalabad Campus

In recent decades, a number of protocols for Remote data integrity checking(RDIC) have been proposed. Identity(ID) based RDIC protocols are constructed to guarantee cloud data integrity and data privacy. The known protocols for RDIC always assume that the Private key generator(PKG) is a trusted one, but in real-world applications by corrupt PKG, malicious Cloud server(CS) can easily cheat the third party auditor that the data owner’s outsourced data are kept safe through the data has been deleted or altered. In this paper, we explore the novel model of RDIC with untrusted PKG and malicious CS, by employing the partial key method and Authentication, authorization, accounting(AAA) *** construct a new ID-based RDIC, which provides the ID revocation and key updation. The experimental evaluations show that our scheme is more efficient than known ones.

关键词： Cryptography Protocols File organisation Data security Internet software AAA service Cloud storage Data integrity Partial private key Revocation Untrusted PKG

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Fabrication of NiO coated SiO_2 and SiO_2 coated NiO for the removal of Pb^(2+) ions

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Chinese Chemical Letters 2014年第5期25卷 819-822页

作者： Saba Noor Muhammad Waseem Umer Rashid Muhammad Anis-ur-rehman Wajid rehman Khalid Mahmood Department of Chemistry Hazara University Department of Physics COMSATS Institute of Information Technology

We have prepared silica,SiO2coated NiO and NiO coated SiO2by sol-gel *** physicochemical properties of the desired materials were investigated by surface charge properties,scanning electron microscopy（SEM）,energy dispersive X-ray（EDX） spectroscopy,surface area measurements and X-ray diffraction（XRD） *** point of zero charge（PZC） of the solid was determined by the salt addition *** coated materials,two PZC values were noted representing the surface charge of their *** SEM image of SiO2coated NiO displays a uniform coating of silica on the surface of NiO whereas in case of NiO coated SiO2,a honeycomb like appearance was observed with highly porous *** the diffractograms of NiO,the characteristic peaks were suppressed in NiO coated silica however,no diffraction peak could be seen in SiO2coated *** adsorption technique was applied for the removal of Pb2＋ions from aqueous *** sorption trend for Pb2＋ions was observed in the order of NiO coated SiO2〉 SiO2coated NiO 〉 NiO 〉 *** trend confirms that the coated materials have more sorption capacities than their parent counterparts.

关键词： Characterization Coated materials Lead removal Sol–gel

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Parametric Regression Approach for Gompertz Survival Times with Competing Risks

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Communications on Applied Mathematics and Computation 2022年第4期4卷 1175-1190页

作者： H.rehman N.Chandra Department of Statistics Ramanujan School of Mathematical SciencesPondicherry UniversityPuducherry 605014India

Regression models play a vital role in the study of data regarding survival of *** Cox proportional hazards model for regression analysis has been frequently used in sur-vival *** survival studies,it is also possible that survival time may occur with multiple occurrences of event or competing *** situation of competing risks arises when there are more than one mutually exclusive causes of death(or failure)for the person(or subject).In this paper,we developed a parametric regression model using Gompertz distribution via the Cox proportional hazards model with competing *** discussed point and interval estimation of unknown parameters and cumulative cause-specific hazard function with maximum-likelihood method and Bayesian method of *** Bayes estimates are obtained based on non-informative priors and symmetric as well as asym-metric loss *** observe the finite sample behaviour of the proposed model under both estimation procedures,we carried out a Monte Carlo simulation *** demon-strate our methodology,we also included real data analysis.

关键词： Competing risks Regression model Cause-specific hazard Gompertz distribution Parametric model Bayesian estimation MCMC algorithm

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Resource Allocation for Two-Way Amplify and Forward OFDM Relay Networks

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China Communications 2017年第8期14卷 76-82页

作者： Zhijun Liu Xiaofeng Tao Waheed ur rehman Wireless Technology Innovation Institute Key Laboratory of Universal Wireless CommunicationsBeijing University of Posts and TelecommunicationsBeijingChina

Physical-layer network coding(PNC) promises substantial theoretical gain to achieve the maximum system throughput in cooperative relay transmission. However, with the increasing global warming, how to reduce power consumption while satisfy system throughput requirement is becoming a vital issue. In this paper, we investigate energy-efficiency resource allocation(RA) based on PNC with amplify-and-forward(AF) protocol in orthogonal frequency division multiple(OFDM) bidirectional transmission. To minimize the overall transmit power consumption with required system throughput requirement, we consider joint subcarriers and power allocation and formulate the objective task into a constrained optimization problem where the best relay node is selected to minimize total transmit power. The closed form optimization power allocation solutions are acquired by analytical derivation. Based on derivation, we propose a novel optimal energy-efficient power allocation(OE-PA). Numerical results are given to evaluate the performance of the derived scheme as compared to other schemes and show that our scheme has signifi cant improvement to energy saving.

关键词： Energy-effi ciency Resource allocation physical-layer network coding OFDM system

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CXCL12/SDF-1α Activates NF-κB and Promotes Oral Cancer Invasion through the Carma3/Bcl10/Malt1 Complex

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International Journal of Oral Science 2009年第3期1卷 105-118页

作者： Aasia O. rehman Cun-yu Wang Laboratory of Molecular Signaling Division of Oral Biology and Medicine UCLA School of Dentistry Los Angeles USA

Aim To determine how SDF-1α/CXCR4 activates nuclear factor-kappa B （NF-κB） and promotes oral squamous cell carcinoma （OSCC） *** A lentivirus-based knockdown approach was utilized to deplete gene expression. NF-κB activation was evaluated by Western blot analysis and electrophoretic mobility shift （EMSA）. Results We show that the activation of NF-κB by CXCR4 occurs through the Carma3/Bcl10/Maltl （CBM） complex in OSCC. We found that loss of components of the CBM complex in HNSCC can inhibit SDF-1α induced phosphorylation and degradation of IκBα, while TNFα induced IKK activation remains unchanged. Further, we identified a role for novel and atypical, but not classical, PKCs in activating IKK through CXCR4. Importantly, inhibition of the CBM complex leads to a significant decrease in SDF-1α mediated invasion of OSCC. Conclusion The CBM complex plays a critical role in CXCR4-induced NF-κB activation in OSCC. Targeting molecular components of the NF-κB signaling pathway may provide an important therapeutic opportunity in controlling the progression and metastasis of OSCC mediated by SDF-1α.

关键词： CXCR4 NF-κB head and neck cancer invasion signal transduction

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INTERACTION OF POLYVINYLPYRROLIDONE WITH METAL CHLORIDE AQUEOUS SOLUTIONS

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Chinese Journal of Polymer Science 2004年第6期22卷 581-584页

作者： Mohammad Saleem Khan Khaista Gul Najeeb Ur rehman National Center of Excellence in Physical Chemistry University of Peshawar Peshawar 25120 PakistanNational Center of Excellence in Physical Chemistry University of Peshawar Peshawar 25120 PakistanNational Center of Excellence in Physical Chemistry University of Peshawar Peshawar 25120 Pakistan

Interactions of polyvinylpyrrolidone (PVP) with metal chlorides (MgCl 2 , CaCl 2 , KCl and BaCl 2 ) have been investigated by viscometric and spectrophotometric techniques in aqueous solutions. Intrinsic viscosity [η] of (PVP) has shown a discontinuity with varying concentration of metal chlorides. The decreasing order of effectiveness of cation is K 1+ > Ca 2+ > Mg 2+ > Ba 2+ for poly(vinylpyrrolidone) solution. Changes in the absorption spectra of the cosolutes were observed in the presence of PVP in the lower limit of the UV-visible region i.e. 200-210 nm. These changes were attributed to interaction of PVP molecules with the cosolute molecules. As the concentration of the cosolute increased, a red shift in the peaks was observed, indicating an increase in interaction between PVP and cosolutes.

关键词： Polyvinylpyrrolidone PVP Metal chlorides Interaction Intrinsic Viscosity

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Multi-Scale Attention-Based Deep Neural Network for Brain Disease Diagnosis

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Computers, Materials & Continua 2022年第9期72卷 4645-4661页

作者： Yin Liang Gaoxu Xu Sadaqat ur rehman Faculty of Information Technology College of Computer Science and TechnologyBeijing Artificial Intelligence InstituteBeijing University of TechnologyBeijing100124China Department of Natural and Computing Science University of AberdeenAberdeenU.K

Whole brain functional connectivity(FC)patterns obtained from resting-state functional magnetic resonance imaging(rs-fMRI)have been widely used in the diagnosis of brain disorders such as autism spectrum disorder(ASD).Recently,an increasing number of studies have focused on employing deep learning techniques to analyze FC patterns for brain disease ***,the high dimensionality of the FC features and the interpretation of deep learning results are issues that need to be addressed in the FC-based brain disease *** this paper,we proposed a multi-scale attention-based deep neural network(MSA-DNN)model to classify FC patterns for the ASD *** model was implemented by adding a flexible multi-scale attention(MSA)module to the auto-encoder based backbone DNN,which can extract multi-scale features of the FC patterns and change the level of attention for different FCs by continuous *** model will reinforce the weights of important FC features while suppress the unimportant FCs to ensure the sparsity of the model weights and enhance the model *** performed systematic experiments on the large multi-sites ASD dataset with both ten-fold and leaveone-site-out *** showed that our model outperformed classical methods in brain disease classification and revealed robust intersite prediction *** also localized important FC features and brain regions associated with ASD ***,our study further promotes the biomarker detection and computer-aided classification for ASD diagnosis,and the proposed MSA module is flexible and easy to implement in other classification networks.

关键词： Autism spectrum disorder diagnosis resting-state fMRI deep neural network functional connectivity multi-scale attention module

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DFT studies of thermoelectric properties of R-Au intermetallics at 300 K

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Journal of Rare Earths 2018年第2期36卷 197-202页

作者： Sardar Ahmad Rashid Ahmad Muhammad Bilal Najeeb Ur rehman Center for Computational Materials Science University of Malakand Department of Chemistry University of Malakand Department of Physics University of Malakand

Thermoelectric and electronic properties of cubic bi-intermetallics R-Au（R = Tb, Ho. Er. Tm and Yb）compounds were explored. Electronic properties i.e. density of states and band structure were computed using first principles calculations which proved the metallic nature of these compounds. Post-DFT（BoltzTraP） calculations were carried out to explore their thermoelectric properties like electrical conductivities. Seebeck coefficient, electronic thermal conductivities and figure of merit. The highest Seebeck coefficient and figure of merit were found for YbAu among these compounds which are 105 μV/K and 0.285 respectively. All the calculations were carried out at 300 K. Large values of figure of merit obtained for these compounds at room temperature indicate that these materials can be used for thermoelectric devices however need experimental verification.

关键词： DFT Seebeck coefficient Figure of merit Thermal conductivity Electrical conductivity R-Au

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