Piezoceramic/polymer composites with 1-3 connectivity are the most extensively studied and utilized for different applications among existing 10 types of diphasic composites. This type of composite consists of individual piezoceramic rods or fibers aligned in the direction parallel to poling and embedded in a polymer matrix. The piezoceramic fiber or rods play an active role for energy conversion between the mechanical and electrical energy, while the polymer phase acts as a passive medium and transfers the mechanical energy between the piezoelectric ceramic and surrounding with which the composite interacts. These composites are widely used in underwater hydrophone applications, ultrasound actuators and sensors in medical diagnostic devices. In this study, piezoceramics modified compositions; Pb/Co doped barium titanate (Ba0.95Pb0.05)(Ti0.99Co0.01)O3 (BT-PC) and Sr doped lead zirconate titanate (Pb0.94Sr0.04)(Zr0.52Ti0.48)O3 (PZT-S) were synthesized through solid state reaction method. Self-synthesized BT-PC powder has particle size ~0.4μm and after sintering and poling its key properties were; εr= 1100, d33= 136pC/N, g33= 14×10-3 Vm/N, kt=31%, and tanδ= 0.005. Likewise, the basic properties of the PZT-S were; εr= 1327, d33= 335pC/N, g33= 29×10-3 Vm/N, kt=45%, and tanδ= 0.030. Beside these, a novel Pbfree potassium sodium niobate (KNN) based optimized composition 0.9475(Li0.02(Na0.53K0.48)0.98)(Nb0.80Ta0.20)O5-0.0525AgSbO3-0.5wt.%MnO2, (LKNNT -AS-M) with electrical properties; εr= 1927, d33= 287pC/N, g33= 17×10-3 Vm/N, kt=38%, and tanδ= 0.038 was also used as an active phase. Monothane-A70, araldite- F, and Epo-Tek 301 were used as a passive polymer matrix in this work. Three different techniques named as; a novel die-pressing technique, modified align-and-fill, and improved dice-and-fill technique were used for the fabrication of 1-3 composites. Several series of the composites including; BT-PC/monothane-A70, PZT-S/monothane-A70, PZT-S/araldite-F, and LKNNT-AS-M/Epo-Tek 301 with varying piezoceramics rods diameter, spacing between the rods and aspect ratio were developed. The composites developed through die-pressing and align-and-fill techniques possess piezoceramics rods diameter ~1.20mm and ~0.78mm respectively with ceramics contents 11-35 vol. %. However, with dice-and-fill process the LKNNTxiv AS-M ceramic pillars cross-sectional dimensions were 50´50μm with relatively high aspect ratio up to 11. In addition, an underwater transducer with sample changing options was developed indigenously. Disc shape samples of monolithic piezoceramic and 1-3 composite were assembled in the self-designed transducer individually. Transducer’s underwater voltage receiving sensitivity (Sh) and transmitting voltage response (Sv) were investigated in the frequency range 10-200 kHz using a calibrated projector method with pulse technique Developed 1-3 composites were passed through comprehensive microstructural, dielectric, elastic and resonance investigations. Results revealed that all the fabricated 1-3 composites possess clear thickness resonance modes without any mode coupling. The BT-PC/monothane-A70 composites exhibited thickness coupling factor kt (~44%), figure of merit FOM (up to 7169fm2/N), acoustic impedance Z (8-13Mrayl) and elastic stiffness C33 D (36-65GPa). The PZT-S based composites exhibited superior properties due to high piezoelectric charge coefficient (d33~335 pC/N) and high electromechanical coupling coefficient (k33~67%) of PZT-S compared to BT-PC piezoceramic. In addition, low stiffness (C33 D ~ 21-55 GPa) PZT-S/monothane-A70 composites have better acoustic impedance (Z ~ 6-14 Mrayl), high charge coefficient (d33~202-271 pC/N), high hydrostatic charge and voltage coefficients (dh ~ 136-171 pC/N, gh ~ 33- 114×10-3 Vm/N) and high figure of merit (FOM ~ 4488-19364 fm2/N) compared to the PZT-S/araldite-F composites encompassing high stiffness (C33 D ~ 23-60 GPa). The Pb-free LKNNT-AS-M/Epo-Tek 301 composites also exhibited the enhanced properties such as higher thickness factor kt ~63-67%, lower planar factor kp ~27-34%, higher kt/kp ratio ~2.3, low electrical (tanδ ~0.027) and mechanical (Qm ~9) losses, encouraging acoustic impedance Z ~4.2-7.8Mrayl and ~5 times higher voltage coefficient g33 compared to LKNNT-AS-M piezoceramic. Likewise, the underwater results revealed that the transducer with 1-3 PZT-S/araldite-F sample exhibited better voltage receiving sensitivity Sh (-214dB ref 1V/μPa) due to its ~295% higher piezoelectric voltage coefficient gh (30´10-3Vm/N) compared to PZT-S. The above mentioned promising results of the developed composites indicate that they have the potential to be used as active elements in high performance ultrasonic transducers.
درخت کم تھے، آبادی زیادہ اور ہوا اِس قدر آلودہ تھی کہ لوگ سانس لینے کی خاطر آکسیجن سلینڈر اپنے ساتھ رکھتے۔۔۔جگہ جگہ آکسیجن اسٹیشن بن گئے تھے جہاں لوگ لمبی قطاروں میں اپنی اپنی باری کا انتظار کرتے رہتے۔۔۔بڑی بڑی کمپنیاں دن رات اپنے اشتہارات تقسیم کرتی رہتیں کہ اگر اپنے پھیپھڑوں کو تندرست وتوانا رکھنا چاہتے ہیں تو اُن کی کمپنی کا آکسیجن سلینڈرحاصل کریں،اگرچہ فضا میں آکسیجن اب بھی موجود تھی لیکن اِن کمپنیوں نے جدید تحقیق سے یہ ثابت کر دیا تھا کہ اب بغیر آکسیجن ماسک کے سانس لینا زندگی کے لیے خطرہ ہے سو لوگ سانس لیتے ہوئے گھبرانے لگے۔
آکسیجن کی تقسیم میں بھی طبقاتی نظام رائج تھا، طاقتور کو زیادہ اور آسانی سے آکسیجن دستیاب تھی بلکہ اُنہیں کبھی بھی آکسیجن حاصل کرنے کی خاطر قطار میں نہ کھڑا ہونا پڑتا اور ابھی اُن کے گھروں کے سٹور روم میں کئی سلینڈر پڑے ہوتے کہ نئی کھیپ اُن کے دروازے پر پہنچ جاتی یہی وجہ تھی کہ اُن لوگوں نے کئی کئی سالوں کی ایڈوانس آکسیجن جمع کر رکھی تھی۔۔۔غریب لوگ اپنے پرانے سلینڈر ہاتھوں میں لیے قطار میں کھڑے رہتے، بہت سے لوگ دم گھٹنے کی وجہ جان کی بازی ہار جاتے۔۔اُن کے عزیز رشتہ دار سڑک بند کرکے احتجاج کرتے لیکن طاقتور طبقہ ہمیشہ یہی کہتا کہ ہمیں تمہارے دکھوں کا پوری طرح احساس ہے، جلد کوئی حل نکالتے ہیں، سڑک کھول دو۔۔۔سڑک کھل جاتی لیکن حل نہ نکلتا حتٰی کہ کوئی اور آدمی دم گھٹنے سے ہلاک ہو جاتا۔۔۔۔۔
This is a familiar fact that accountability has a primary, important and key role to reform and develop an individual as well as a society. Quran (The Holy Book) and Sunnah (The Sayings the Prophet Muhammad (PBUH) emphasize the acco-untability and the Seerah (Prophet’s life) is its practical example. The Prophet (PBUH) mentioned the importance of individual accountability, told the people to follow the principle of accountability and also set up a collective account-ability system. On various occasions, He inquired the governors and investigated their financial matters. He also strongly condemned crimes such as exploitation, corruption, deception and cheating; those are the result of lack of accountability and He communicated the Ummah to stay away from the devastating crimes like these. The study of Seerah (the Prophet’s life) shows that He strongly empha-sized the accountability among all other matters. The Prophet (PBUH) used practical measures for justice and equality, giving people their rights and elimin-ating all kinds of oppression, abuse, injustice, exploitation and corruption. It was the effect of the teaching and training of the Prophet (PBUH) that the lives of companion’s رضی اللہ عنہم اجمعین of Prophet Muhammad (PPBUH) are the basic source of guidance for mankind till the world due to accountability. The compa-nions of the Prophet (PBUH) used to arrange the accountability and also self-accountability, as a result, the society was a manifestation of transparency, peace fulness, ideal, and brotherhood. Translation errorThis article explains the need and importance of accountability, role of accountability in the country's development, different types of accountability in the light of Seerah. As a result, firstly, we may be able to step up towards the formation of a righteous society. Secondly the rules and regulations for the establishment of an ideal welfare state in the light of Seerah may come into existence.
Chlorpyrifos (CFS) is one of the most common insecticides found in freshwater ecosystems and
has been detected in agricultural and fishery products worldwide. Acute toxicity assessment was
carried out by24hour LC50 of chlorpyrifos to freshwater fish Oreochromis niloticus. The value
for 24hour LC50 was determined as 37.93 ? 20.02?g/L. The experiment was carried to measure
the effects of different concentrations of chlorpyrifos (CFS) on O. niloticus through the
evaluation of biochemical and hematological parameters in addition to histological examination.
One hundred and twenty O. niloticus were randomly distributed into four groups in triplicates
containing ten fish per aquarium. The first group served as a GC (control group), which is the
non-treated group. The second group G1 was exposed to 1/11
of 24hour LC50. The third groupG2 was exposed to 1/7th
of 24hour LC50. While the fourth group G3 was exposed to1/3
rd of
24hour LC50.The exposure was for 14 days in all treated groups. Fish exposed to CFS showed
histological alterations as compared to control groups. Alterations were more prominent in high
dose group G3. Congestion, necrosis and hemorrhage in gills, degeneration in muscles and
intestine were noticed. In hematological assessment, significant increase in WBCs, LYMP,MCH
and MCV with the increase in dose was noticed while decrease in RBCs, HGB, HCT and MCHC
was observed with increase in dose as compared to control. Significant increase in AST and ALT
was observed.This study provides significant perceptions about the acute toxic effects of CFS on
fish and show potential to be used as biomarkers in further toxicological evaluation studies