ڈاکٹر تارا چند
گذشتہ اکتوبر میں ڈاکٹر تاراچند کے انتقال پر ملال سے بھی ہندوستان میں ایک بڑا علمی خلاء پیدا ہوگیا، وہ الہ آباد کے کایستھ پاٹ شالہ کی مدرسی اور پرنسپلی کے بعد الہ آباد یونیورسٹی کے وائس چانسلر بھی ہوئے، پھر حکومت ہند کے تعلیمی مشیر بنے، ایران میں ہندوستان کی طرف سے سفیر بناکر بھیجے گئے، وہاں سے واپسی پر پارلیمنٹ کے رکن نامزد کئے گئے لیکن ان کی اصلی شہرت اور مقبولیت ایک بلند پایہ مورخ کی حیثیت سے ہوئی، انھوں نے ’’انفلوانس آف اسلام ان انڈین کلچر‘‘ پر ایک مقالہ لکھ کر آکسفورڈ سے ڈاکٹریٹ کی ڈگری حاصل کی، یہ ان کی ابتدائی تحقیقی کوشش تھی، لیکن اس سے بہتر کتاب اس موضوع پر اب تک نہیں نکلی، آخر میں وہ ہسٹری آف دی فریڈم موومنٹ کے بورڈ کے اڈیٹر تھے، ان کی ادارت میں یہ کام بڑی خوش اسلوبی سے انجام پاتا رہا، ان کی تحقیقی تحریروں میں دیدہ دری کے ساتھ بڑی فراخدلی بھی ہوتی، وہ ہندی اردو کی حسین آمیزش یعنی ہندوستانی زبان کے بھی بڑے موئد تھے، اس کے کچھ اچھے نمونے بھی لکھ کر پیش کرتے رہے، ان کی نیک نامی اور مورخانہ بصیرت کی وجہ سے ان کی خوشگوار یادوں کا چراغ علمی حلقہ میں برابر روشن رہے گا۔ (’’ص ، ع‘‘، نومبر ۱۹۷۳ء)
The acceptance of new students (PPDB) using the zoning system was first implemented in Yogyakarta in 2018/2019. This zoning system aims to equalize education and improve the quality of education. This research was conducted to find out how the zoning system policy in Yogyakarta city under the auspices of the Yogyakarta City Education Office. This research uses qualitative approach with case study method. The results of the study showed that the zoning system in Yogyakarta has changed from the previous year. In 2019/2020 the zoning system provides a 10% chance of superior seeds, 30% of school zones, 10% of poor learners, 40% of quality pathways, 5% of out-of-school zoning pathways, and 5% of special pathways such as prospective learners whose parents moved from other regions to Yogyakarta. With this zoning system, the whole community has the opportunity to get a good quality education.
The aim of the present research work is to synthesize flexible polymer based nanocomposites with excellent dielectric properties. Compounds and composites with high dielectric constant are in demand in electronic industry due to their ability to store more charge, while energy dissipation is low there. So it is needed to synthesize materials with ability to store more and more charge. In presented research work, flexible three phase nanocomposite films of graphene/metal/polymer were synthesized with reasonably high dielectric constant or real part of permittivity and very low dielectric loss or imaginary part of permittivity. Ternary nanocomposite films were synthesized by using three different polymers i.e., poly(vinyl alcohol), polyvinylidene fluoride and polydimethysiloxane as matrix. Graphene and two ceramic metals oxides i.e., titania and barium titanate were reinforced in the polymers as conducting and metal additives, respectively. In this way six different types of ternary nanocomposite films with different combinations of fillers and polymers were synthesized. Each ternary nanocomposite series was synthesized by varying w/w of graphene while keeping concentrations of ceramic and polymer constant. After setting optimized conditions for concentrations of graphene, w/w of ceramic filler was varied and concentrations of ceramic and polymer were kept fixed. Each ternary graphene/metal/polymer nanocomposite film was characterized by scanning electron microscopy, X-ray diffraction analysis, raman spectroscopy, fourier transform infrared spectroscopy and thermal gravimetrical analysis to study their morphology, structures, presence of functional groups and thermal stability respectively. Dielectric characterization of each ternary graphene/metal/polymer nanocomposite film was carried out at room temperature. Ternary nanocomposite with highest dielectric constant and lowest dielectric loss were explored for each ternary nanocomposites series. Dielectric constant of poly(vinyl alcohol), Polyvinylidene fluoride and polydimethysiloxane was increased from 13.3, 20.5 and 6.5 to 330, 159.8 and 108.3, respectively, with addition of graphene and titania. While dielectric constant of poly(vinyl alcohol), Polyvinylidene fluoride and polydimethysiloxane was increased from 13.3, 20.5 and 6.5 to 66, 199.9 and 116.9, respectively, with addition of graphene and barium titanate. Even with such high dielectric constant, dielectric loss of all ternary nanocomposites was still very low i.e., less than 5 which is required for energy storage devices. AC conductivity and complex electric modulus of all neat polymers and ternary graphene/metal/polymer nanocomposite films were also calculated and compared. The superiority of this method is that synthesized three phase graphene/ceramic/polymer nanocomposite films have hybrid properties like high dielectric permittivity and low dielectric loss of fillers and flexibility and mechanical strength of polymers. All analyses of graphene/metal/polymer nanocomposite films confirm their excellent capacitive performance. On the basis of results it is concluded that synthesized ternary graphene/metal/polymer nanocomposite films are fairly good candidate to be used as dielectric medium in energy storage devices like capacitors.