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Properties of Phosphoric Acid Doped Poly(benzimidazole/sulfone/siloxane/amide)/Sulfonated Polystyrene/Silica Nanoparticle-based Proton Exchange Membranes for Fuel Cells

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Chinese Journal of Polymer Science 2014年第10期32卷 1319-1328页

作者： ayesha kausar Muhammad Siddiq Nanosciences and Catalysis Division National Centre For Physics Quaid-i-Azam University CampusIslamabad 44000 Pakistan Department of Chemistry Quaid-i-Azam University Islamabad Pakistan

New siloxane and sulfone containing poly（benzimidazole/sulfone/siloxane/amide）（PBSSA） has been prepared for the formation of hybrid membranes （PBSSA/PS-S/SiNPs） with sulfonated polystyrene （PS-S） and 0.1 wt%-2 wt% silica nanoparticles （SiNPs）. Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSAJPS-S/SiNPs nanocomposites increased from 207℃ to 215 ℃. The membranes also had higher ion exchange capacity （IEC） around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10-2.34 S/cm in a wide range of humidity values at 80 ~C which was higher than that of perfluorinated Nafion 117 membrane （1.1 × 10^-1 S/cm） at 80 ~C （94% RH）. A H2/O2 fuel cell using the PBSSA/PS-S/SiNP 2 （IEC 3.01 retool/g） showed better performance than that of Nation 117 at 40 ℃ and 30% RH.

关键词： Poly(benzimidazole/sulfone/siloxane/amide) Sulfonated polystyrene Silica nanoparticles Ion exchange capacity Proton conductivity.

MECHANICALLY AND THERMALLY STABLE BLENDS OF POLY(STYRENE-BUTADIENE-STYRENE) WITH CONDUCTING POLY(THIOUREA-AZO-NAPHTHYL)

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Chinese Journal of Polymer Science 2013年第12期31卷 1623-1631页

作者： ayesha kausar Syed Tajammul Hussain Nanosciences and Catalysis Division National Centre for PhysicsQuaid-i-Azam University Campus

A new aromatic azo-polymer, poly（thiourea-azo-naphthyl）（PTAN）, has been synthesized using 1-（5- thiocarbamoylaminonaphthyl）thiourea and diazonium salt solution of 2,6-diaminopyridine. PTAN was easily processable using polar solvents and had high molar mass 57 × 10^3 g/mol. Electrically conducting, mechanically and thermally stable rubbery blends of poly（styrene-butadiene-styrene）（SBS） triblock copolymer and PTAN were produced by solution blending technique. FESEM of SBS/PTAN blends revealed nano-scale dispersion of the conducting filler showing good adhesion between the matrix and PTAN. Remarkable effects of azo-content on the conductivity of SBS-based blends have been observed. Accordingly, PTAN loading from 10 to 60 wt% increased the conductivity from 1.24 to 1.66 S/cm. Relationship between PTAN loading and thermal stability of the materials was also investigated. With increasing the PTAN content, 10% gravimetric loss was increased from 484 to 500 ℃, while glass transition was enhanced from 119 to 126 ℃. Thermal and conducting data of the blend showed better results relative to pure elastomer but were lower than those of the conducting filler. Similarly, the tensile strength （57.35-62.33 MPa） of SBS/PTAN was improved relative to there of SBS. Fine balance of properties renders new materials fairly better than the existing elastomeric blends used in a number of applications.

关键词： Poly(thiourea-azo-naphthyl) SBS Electrical conduction Thermal stability Tensile strength.

Thermal, Mechanical and Electrical Studies of Novel Shape Memory Polyurethane/Polyaniline Blends

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Chinese Journal of Polymer Science 2015年第9期33卷 1313-1324页

作者： Rabia Sattar ayesha kausar Muhammad Siddiq Department of Chemistry Quaid-i-Azam University Nanosciences and Catalysis Division National Centre for Physics Quaid-i-Azam University Campus

Shape memory polymer （SMP） blends based on polyurethane （PU） and polyaniline （PANI） were prepared via chemical in situ polymerization process. The thermal, mechanical, electrical and shape memory properties were investigated. The structural characterization and morphology of the polymer blends were inspected by Fourier transform infrared （FTIR） and scanning electron microscopy （SEM）, respectively. The 1 wt% of PANI loading enhanced the thermal stability of the system up to 339 ~C. According to differential scanning calorimetry （DSC）, the glass transition temperature （Tg） and melting temperature （Tm） of PU/PANI blends increased with the polyaniline loading （0.1 wt%-l wt%）. Improved mechanical properties such as tensile strength and Young＇s modulus of PU matrix were also observed with PANI. Moreover, the electrical conductivity of PU/PANI blends was also found to be a function of PANI loading. Remarkable recoverability of thermally triggered shape memory （SM） behavior to the extent of 96% was achieved for 1 wt% PANI blend.

关键词： Shape memory Polyurethane Polyaniline Blends Conductivity.

Mixed Matrix Membranes of Polysulfone/Polyimide Reinforced with Modified Zeolite Based Filler: Preparation, Properties and Application

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Chinese Journal of Polymer Science 2018年第1期36卷 65-77页

作者： Sedra Tul Muntha Muhammad Siddiq ayesha kausar Anum Khan Department of Chemistry Quaid i Azam University Department of Microbiology Quaid i Azam University

In this work, polysulfone/polyimide（PSf/PI） mixed matrix membranes were fabricated by reinforcement of modified zeolite（MZ） particles through solution casting method for investigation of antibacterial activity against two gram negative bacteria（Salmonella typhi, Klebsella pneumonia） and two gram positive bacteria（Staphylococcus aureus, Bacillus subtilis）. The modified zeolite particles were incorporated to PSf and PI matrix and the influence of these particles on thermal, mechanical and structural properties was evaluated. The morphological evolution was investigated through scanning electron microscopy（SEM） and transmission electron microscopy（TEM） analysis, which revealed good compatibility between organic polymer matrix and inorganic filler. Mechanical stability was investigated by tensile testing while thermal analysis was evaluated by thermogravimetric analysis（TGA） and differential scanning calorimetry（DSC）. This revealed improvement in thermal properties with increasing filler concentration from 1 wt% to 10 wt%. Structural analysis was successfully done using X-ray diffraction analysis（XRD） and Fourier transform infrared（FTIR） spectroscopy. Solvent content of fabricated mixed matrix membranes was observed to decrease while moving from more hydrophilic to less hydrophilic solvent. However, addition of filler content enhanced the porosity of fabricated membranes. The synthesized mixed matrix membranes exhibited good antibacterial activity and the highest activity was shown by PSf/PI/MZ mixed matrix membrane. Therefore, the combination effect of PSf, PI and MZ sufficiently enhanced the antibacterial activity of mixed matrix membranes.

关键词： Modified zeolite Polysulfone/polyimide blend membrane Mixed matrix membrane Thermal analysis Antibacterial activity

A Review Featuring Fabrication, Properties and Applications of Carbon Nanotubes(CNTs) Reinforced Polymer and Epoxy Nanocomposites

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Chinese Journal of Polymer Science 2018年第4期36卷 445-461页

作者： Sobia Imtiaz Muhammad Siddiq ayesha kausar Sedra Tul Muntha Jaweria Ambreen Iram Bibi Department of Chemistry Quaid-i-Azam University Department of Physics Comsats Institute of Information Technology Department of Chemistry Hazara University

Carbon nanotubes（CNTs） have long been recognized as the stiffest and strongest man-made material known to date. In addition, their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications. However, due to their miniature size, the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers. In order to enhance their chemical affinity to engineering polymer matrices, chemical modification of the graphitic sidewalls and tips is necessary. The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area. Recently, carbonaceous nano-fillers such as graphene and carbon nanotubes（CNTs） play a promising role due to their better structural and functional properties and broad range of applications in every field. Since CNTs usually form stabilized bundles due to van der Waals interactions, they are extremely difficult to disperse and align in a polymer matrix. The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix, the assessment of the dispersion, and the alignment and control of the CNTs in the matrix. An overview of various CNT functionalization methods is given. In particular, CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion. In addition, discussions on mechanical, thermal, electrical, electrochemical and applications of polymer/CNT composites are also included.

关键词： Polymer nanocomposites CNTs Epoxy Conducting polymers RAMs

Seroprevalence of Toxoplasma gondii infection in domestic animals of Mohmand agency,Pakistan

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Journal of Coastal Life Medicine 2013年第1期 72-75页

作者： Mudassir Shah Muhammad Zahid Aftab Alam Sthanadar Pir Asmat ayesha kausar Abdul Hamid Jan Department of Zoology Islamia College University PeshawarKPPakistan Department of Zoology University of PeshawarKPPakistan

Objective:To determine the prevalence of toxoplasmosis among domestic animals of Mohmand Agency,***:Indirect haemagglutination test was used to detect Toxoplasma gondii(***)antibodies in the ***:Out of 384 domestic animals,124(32.29%)were seropositive for antibodies of *** antibodies were detected in 56 out of 104 examined goats(53.84%).The seropositivity in male and female goats were 20(38.46%)and 36(69.23%)*** seropositivity of *** in sheep was 36%(n=100)while the prevalence in female sheep was higher(41.66%)as compared to male sheep(30.76%).A total of 8 out of 48 male cows were detected seropositive(16.66%)and 8 out of 32 female cows were detected seropositive(25%).Lowest prevalence was detected in buffaloes which was 16%(n=100).Out of 52 male buffaloes 4 were detected seropositive for *** antibodies(7.69%)while in female buffaloes was 25%(n=48).The seroprevalence of *** antibodies was higher in goats and lower in ***:The findings of the present study indicate that *** infection is high in domestic animals in Mohmand agency,Pakistan,which has implications for public health in this *** control strategies and suitable measures should be carried out rationally in this region,in order to lower the risk of exposure to ***.

关键词： Antibodies Domestic animals Seroprevalence Toxoplasma gondii

Level Statistics Crossover of Chiral Surface States in a Three-Dimensional Quantum Hall System

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Chinese Physics Letters 2021年第5期38卷 99-103页

作者： Rubah kausar Chao Zheng Xin Wan Zhejiang Institute of Modern Physics Zhejiang UniversityHangzhou 310027China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.

关键词： Level Statistics Crossover of Chiral Surface States in a Three-Dimensional Quantum Hall System Quantum

Enviro-Friendly Synthesis of Silver Nanoparticles Using Berberis lycium Leaf Extract and Their Antibacterial Efficacy

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 75-80页

作者： Ansar Mehmood Ghulam Murtaza Tariq Mahmood Bhatti Rehana kausar Department of Botany University of Azad Jammu and Kashmir (UAJK)Muzaffarabad-13100Pakistan Department of Chemical and Material Engineering Pakistan Institute of Engineering and Applied Sciences(PIEAS)Islamabad-45650Pakistan

In the present study, an enviro-friendly synthesis of silver nanoparticles from Berberis lycium Royle leaf extract and their antibacterial efficacy against five pathogenic bacteria were investigated. This biosynthesis technique is proved to be advantageous over physical and chemical methods as no toxic chemicals are used. The structural and morphological characterization was made by UV-visible spectroscopy, scanning electron microscopy, and transmission electron microscopy. The synthesized nanoparticles were oval, rectangular, and spherical in shape, size ranges from 8 to 100 nm and exhibited an absorption peak at 458 nm. The biosynthesized silver nanoparticles have shown good antibacterial effect toward tested bacteria. It is believed that these biosynthesized silver nanoparticles can play a vital role in nano-based products in future.

关键词： Antibacterial Berberis lycium Enviro-friendly Silver nanoparticles

A Fast Panoptic Segmentation Network for Self-Driving Scene Understanding

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Computer Systems Science & Engineering 2022年第10期43卷 27-43页

作者： Abdul Majid Sumaira kausar Samabia Tehsin Amina Jameel Department of Computer Science Bahiria UniversityIslamabadPakistan Department of Software Engineering Bahiria UniversityKarachiPakistan

In recent years,a gain in popularity and significance of science understanding has been observed due to the high paced progress in computer vision techniques and *** primary focus of computer vision based scene understanding is to label each and every pixel in an image as the category of the object it belongs *** it is required to combine segmentation and detection in a single *** many successful computer vision methods has been developed to aid scene understanding for a variety of real world *** understanding systems typically involves detection and segmentation of different natural and manmade things.A lot of research has been performed in recent years,mostly with a focus on things(a well-defined objects that has shape,orientations and size)with a less focus on stuff classes(amorphous regions that are unclear and lack a shape,size or other characteristics Stuff region describes many aspects of scene,like type,situation,environment of scene *** hence can be very helpful in scene *** methods for scene understanding still have to cover a challenging path to cope up with the challenges of computational time,accuracy and robustness for varying level of scene complexity.A robust scene understanding method has to effectively deal with imbalanced distribution of classes,overlapping objects,fuzzy object boundaries and poorly localized *** proposed method presents Panoptic Segmentation on Cityscapes ***-V2 is used as a backbone for feature extraction that is pre-trained on ***-V2 with state-of-art encoder-decoder architecture of DeepLabV3+with some customization and optimization is employed Atrous convolution along with Spatial Pyramid Pooling are also utilized in the proposed method to make it more accurate and *** promising and encouraging results have been achieved that indicates the potential of the proposed method for robust scene understanding in a fast and

关键词： Panoptic segmentation instance segmentation semantic segmentation deep learning computer vision scene understanding autonomous applications atrous convolution