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Stablization of Zirconia Using Different Experimental Methods and Their Applications

Thesis Info

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Author

Bashir, Mahwish

Program

PhD

Institute

University of the Punjab

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Microelectronics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9555/1/Mahwish_Bashir_Microelectronics_Nanotechnology_2017_UoP_Punjab_11.09.2018.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727231980

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Zirconia ceramics have received much attention due to its good mechanical strength, good thermal properties, biocompatibility and white color. These properties make zirconia more suitable for orthopedic and maxillofacial implants. Among three phases of zirconia (monoclinic, tetragonal and cubic), tetragonal zirconia is more suitable for implants and coatings, but tetragonal zirconia is stable at higher temperatures and transforms to monoclinic phase upon cooling. This research includes preparation and characterizations of zirconia coatings and nanostructures. Different routes of sol-gel preparation were used. Detailed study was carried out to optimize gelation agent, pH and molarity of the sol. Samples were prepared at different molarities (0.025, 0.050, 0.075, 0.10 and 0.125M) in acidic (pH 2) and basic mediums (pH 9) using three different gelation agents (NaOH, NH3 and NH4OH). Un-doped and doped zirconia nanostructures and coatings were studied in this research work with water as solvent. Molarity of the sol had a significant effect on the volume fraction of tetragonal zirconia content with a relatively small crystallite size <30nm. pH of the sol also played an important role for tetragonal zirconia formation; pH of zirconia sol was varied from 1 to 11. Optimization of stabilized tetragonal zirconia under as-synthesized conditions was obtained for samples prepared at molarity 0.1M in basic medium (pH 9) using NH3 as gelation agent. Fourier transform infrared spectroscopy (FTIR) results were consistent with XRD data that confirmed the formation of phase pure tetragonal zirconia under as-synthesized conditions. SEM micrographs revealed the formation of well-separated and well-defined nanoparticles of size range 30-50 nm that is compatible for implants. Along with thermal stability problem another drawback of zirconia is lack of bonding with body fluid. In order to increase its bonding strength some organic additives (Glucose and Fructose) have been added in zirconia. Nanowires of zirconia with diameter of 8nm were observed in case of organic additive zirconia with hardness ~1500HV. Effect of biocompatible dopant Fe3O4 in zirconia sol for stabilization of tetragonal content has also been studied to increase its application area. Fe3O4 was used as a dopant with acidic (pH 4) and basic (pH 10) nature with 2-10wt%. Pure tetragonal zirconia content has been observed under XRD study at 8-10wt% of basic (pH 10) nature. It is worth mentioning that biocompatible Fe3O4 has been used for the first time for stabilization of tetragonal zirconia. This optimized zirconia was coated on teeth that were soaked in several foods and beverages. Results reveal that after coatings teeth show no loss to enamel and weight even in strong acidic and basic mediums.
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مولانا فضل الحسن حسرتؔ موہانی

مولانا فضل الحسن حسرتؔ موہانی
شاید جہاں سے حسرتِ دیوانہ چل بسا
ہاں ہاں جب بھی تو چشمِ جنون اشکبار ہے
بالآخر کئی مہینہ کی موت و حیات کی کشمکش کے بعد ہمارے قافلہ آزادی کا پہلا حدی خوان اور میرکاروان بھی کوچ کرگیا اور گلستانِ تغزل کا بلبلِ نغمہ سنج ہمیشہ کے لیے خاموش ہوگیا، یعنی گذشتہ ۱۳؍ مئی کو سیدالاحرار مولانا فضل الحسن حسرت موہانی نے اس دارِ فانی کو الوداع کہا کلُّ مَنْ عَلَیھْاَ فَانٍ ویبقی وجہ رَبِّکَ ذوالجلال وَالاکرام۔[الرحمن:۲۶۔۲۷]
مولانا حسرت کی ذات ستودہ صفات مجموعہ اضداد و کمالات تھی، وہ ملک و وطن کے جانباز مجاہد اور شاعرِ رنگین نوا بھی، انقلابی سوشلسٹ بھی تھے اور صاحبِ و جدوحال صوفی بھی، بوریہ نشینِ فقرومسکنت بھی اور مسندنشینِ غروتمکنت بھی انہوں نے اس زمانہ میں انگریزوں کی مخالفت کی صدا بلند کی ، جب اسکی پاداش دارورسن تھی، اس زمانہ میں آزادی کا صور پھونکا جب کانگریس بھی اس نام سے گھبراتی تھی اور بڑے بڑے محبِ وطن آزادی کے کھلونوں میں الجھے ہوئے تھے، اور اس زمانہ میں قوم و ملک کے لیے قید و بند کی مصیبتیں جھیلیں جب جیل سیاسی تفریح گاہ نہیں بلکہ حقیقۃً قید محن تھے، انہوں نے اس راہ میں جو قربانیاں کیں اور جتنے مصائب اٹھائے اسکی مثال اس زمانہ کے کسی لیڈر کی زندگی میں مشکل ہی سے مل سکتی ہے اور موجودہ مدعیانِ آزادی کو توآزادی کا شعور و احساس بھی نہیں تھا، بلکہ حق یہ ہے کہ گاندھی جی بھی ایک عرصے تک اس راہ میں ان سے بہت پیچھے رہے، حسرت کایہ دعوی اولیت بالکل صحیح ہے۔
تو نے کی حسرت عیاں تہذیبِ رسمِ عاشقی
اس سے پہلے اعتبارِ شانِ رسوائی نہ تھا
وہ اخلاص و صداقت حق گوئی و حق پرستی اور جرات و بے باکی کے جس درجہ پر تھے،...

ASSESSMENT PRACTICES OF SPEECH AND LANGUAGE PATHOLOGISTS FOR COGNITIVE COMMUNICATION IMPAIRMENT AFTER TRAUMATIC BRAIN INJURY

Background of the Study: The aim of the present research was to examine the assessment practices of Speech-Language Pathologists for Cognitive Communication Disorders after Traumatic Brain Injury. Methodology: It was a cross-sectional survey method, a convenient sampling technique. Research was carried out from January 2021 to June 2021. The sample size was n=21, out of which n= 9 (42.8%) participants, each from Rawalpindi and Islamabad n= 3 (14.4%) participants from Lahore filled in their responses. Medium; being Online, the questionnaire was distributed either through email, WhatsApp or Facebook MessengerApp. SLPs who were undergraduates or who had no experience working with TBI clients were excluded. Questionnaire included 12 items. Responses of research participants were recorded using Google Forms and presented in the form of n (%). The data were analyzed using descriptive analysis, and chi-square analysis was performed to confirm the association between settings, city of practice and years of experience through Statistical Package of Social Sciences (SPSS) Version 22.0. Results: Speech-Language Pathologists reported that they routinely assessed (62% each) Receptive and Expressive communication. However; less than half of the participants routinely evaluated domains like verbal pragmatic skills (43.3%), functional communication (33.3%) and phonemic awareness (33.3%). SLPs assessed their clients by employing tests like MoCA (55.62%), Quick Aphasia Battery (18.75%), Cognitive Assessment (LOTCA Protocol) (14.35%) and a combination of Formal (48%) and Informal (52%) clinical interviews. Conclusion: Informal discourse assessment is incorporated more frequently as compared to informal discourse evaluation in assessment practices of Speech-Language pathologists of Pakistan for cognitive communication impairment followed by traumatic brain injury.

Eff Ect of Compa Atibilit Enha Ty Anceme Ent on Structu S Ure, Mo Orphol Logy an the Rmo-M Echani Nd Ical Proper P Rties of Polyi F Imide/S Silica N Nanoco Omposi Tes

Polyimide/silica (PI/silica) and poly(hydroxyl imide)/silica (PHI/silica) nanocomposites containing pure as well as organically modified silica network structures have been prepared through the sol-gel process from solution mixtures of poly(amic acid) (PAA) and alkoxysilanes. Two types of PAAs were employed. The first was obtained from the reaction of pyromellitic dianhydride (PMDA) with oxydianiline (ODA) in dimethylacetamide as a solvent. The second was prepared from the reaction of PMDA with a mixture of 3,3′- diamino-4,4′-dihydroxybiphenyl and ODA. The hybrid films obtained by solvent elution technique were thermally cured to carry out the imidization process and the silica network formation. The effect of compatibility enhancement achieved through the modification of polymer backbone as well as through the use of non-silane and silane-terminated imide coupling oligomers on structure and properties of hybrids was studied and compared with the systems where reinforcement of the matrix was achieved using pure silica. The presence of pendant hydroxyl groups on polymer backbone played an important role in dictating the morphology of the PHI/silica hybrids. A model namely “Retain and React” based on two-step process has been proposed to explain the formation of polymer- modified silica clusters composed of co-continuous nano-domains with diffused boundaries as the previously proposed models failed to explain the observed morphology. The introduction of coupling oligomers in hybrid systems impeded the agglomeration of nano- sized silica domains and promoted the formation of novel fibril structures connecting the organic and inorganic phases together. Significant reduction in the roughness of the surfaces in the hybrid materials having modified matrix and silica networks has also been attributed to effect of enhanced coupling. A large shift in the glass transition temperature (Tg) of the hybrid material to higher temperatures confirmed the restricted segmental motion of polymer backbone due to increased interfacial interaction. The high surface-area of the interconnected silica domains stabilized the materials and shifted the decomposition profiles to higher temperatures by providing barriers to heat and mass transport in the hybrid material and thus slowing down the diffusion of oxygen in the matrix. The enhanced polarity coupled with organically modified silica offer an opportunity for improving Tg, reducing the coefficient of thermal expansion and increasing thermal-oxidative stability of polyimide/silica hybrids. The co-continuous and interpenetrating network structure thus produced also improves mechanical properties. Key words: Organic/inorganic hybrids; nanocomposites; polyimide; silica; sol-gel process; compatibilization; morphology; visco-elastic and thermal properties