Judul: Sintesis Dan Karakterisasi Klaster Tetrainti Tembaga(I) Iodida
Abstrak: Unsur-unsur logam pada blok d sering dimanfaatkan dalam dunia penelitian, khususnya di bidang material dan aplikasinya. Salah satu sifat fotofisik yang menarik dari unsur blok d ialah sifat luminesens. Beberapa tahun terakhir mulai dikembangkan kompleks berluminesens dengan atom pusat dari unsur logam d10, seperti Cu(I), yang melimpah keberadaannya di alam. Pada penelitian ini dilakukan sintesis senyawa klaster yang berbasiskan Cu(I), yakni klaster tetrainti tembaga(I) iodida atau [Cu4I4py4]. Klaster ini tidak berwarna pada cahaya tampak dan berwarna kuning ketika dipaparkan lampu ultraviolet (UV). Keberhasilan sintesis ditunjukkan dengan hasil spektrum UV-vis, spektrum fluoresens, mikroskop stereo, dan spektrum inframerah transformasi Fourier (FTIR). Spektrum FTIR dari klaster ini didominasi oleh vibrasi dari gugus piridina. Hasil analisis dengan mikroskop stereo menunjukkan klaster [Cu4I4py4] berbentuk kubus yang terdistorsi. Spektrum emisi senyawa ini maksimum pada panjang gelombang 586.18 nm.
Keyword: Cu(I), fluoresens, sifat fotofisik, senyawa kompleks, tetrainti tembaga(I) iodida

Judul: Sintesis dan Karakterisasi Film Tipis Barium Stronsium Titanat (Ba0,5Sr0,5TiO3) didadah Tembaga (II) Asetat (Cu(CH3COO)2)
Abstrak: Film Barium Stronsium Titanat (Ba0,5Sr0,5TiO3) didadah dengan variasi konsentrasi tembaga (II) asetat (0%, 2%, 4%, 6%) telah berhasil disintesis di atas substrat Si (100) tipe-p menggunakan metode CSD melalui spin coating dengan kecepatan putar 8000 rpm. Proses annealing dilakukan pada suhu 8500C dan ditahan selama 8 jam dengan kelajuan suhu sebesar 1,670C/menit, lalu mengikuti proses pendinginan hingga suhu kamar selama 13 jam. Karakterisasi sifat optik film Ba0,5Sr0,5TiO3 dengan konsentrasi pendadah tembaga asetat (0%, 2%, 4%, 6%) memiliki nilai energi bandgap berturut-turut sebesar 3,0862 eV; 2,9690 eV; 2,8080 eV; dan 2,7475 eV. Hasil parameter kisi yang diperoleh pada karakterisasi sifat kristal menggunakan XRD adalah berturut-turut 4,037 Å; 4,021 Å; 4,003 Å; dan 3,980 Å. Berdasarkan analisis Rietveld dengan menggunakan perangkat lunak MAUD sebagai data pembanding menggunakan literatur didapatkan bahwa Ba0,5Sr0,5TiO3 memiliki struktur kristal berbentuk kubus dengan parameter kisi berturut-turut sebesar 3,918 Å; 3,984 Å; 3,983 Å; dan 3,900 Å. Kata kunci: Ba0,5Sr0,5TiO3, Cramer-Cohen, Kubelka-Munk, MAUD, Tembaga (II) Asetat., Barium Stronsium Titanate (Ba0.5Sr0.5TiO3) film doped with variations in copper (II) acetate concentration (0%, 2%, 4%, 6%) has been successfully synthesized on p-type Si (100) substrate using the CSD method through spin coating with rotation speed of 8000 rpm. The annealing process was carried out at 8500C and held for 8 hours at a speed of 1.670C/min, then followed the cooling process to room temperature for 13 hours. Characterization of optical properties of the Ba0.5Sr0.5TiO3 film with the concentration of copper acetate-dopped (0%, 2%, 4%, 6%) had a bandgap energy value repectively 3.0862 eV, 2.9690 eV, 2.8080 eV, and 2.7475 eV. The result of the lattice parameters obtained on the characterization of crystal properties using XRD are 4.037 Å, 4.021 Å, 4.003 Å, and 3.980 Å respectively. Based on Rietveld analysis using MAUD software as comparison data using literature, it was obtained that Ba0.5Sr0.5TiO3 had a cube-shaped crystal structure with lattice parameters value repectively 3.918 Å, 3.984 Å, 3.983 Å, dan 3.900 Å. Keywords: Ba0.5Sr0.5TiO3, Copper (II) Acetate, Cramer-Cohen, Kubelka-Munk, MAUD
Keyword: Ba0.5Sr0, 5TiO3, Copper (II) Acetate, Cramer-Cohen, Kubelka-Munk, MAUD

Judul: Statistics concept as neural network training stopping criteria to overcome limited data (study case in prediction of palm oil based- Surfactant-MESA surface tension)
Abstrak: There exist situations such as marine ecology where artificial neural network (ANN) implementation must cope with scarce data. Efforts to add more data in this sort of field will most likely be overlooked for being expensive and time consuming. Cross-validation comes across the opportunity of still using ANN to survive this poor data condition while not compromising its generalization. This paper proposed prediction output interval as stopping-criteria employed in 5-fold validation and demonstrated its performance when selecting best hidden layer number of neurons to be used for surfactant-MESA surface tension prediction based on only ten data pairs. Output interval building, derived from statistics concept, was gaining from the fact that there were two experiment repetitions from the case which could be generalized to cases with two measurement repetitions. Repetitions are expected to produce difference. A 95% confidence interval to estimate mean from these difference samples was then used to create output interval for ANN training. Backpropagation ANN with this added stopping criterion successfully gave 1.83 x 10-3 cross-validation MSE comparable to 2.72 x 10-3 of overfitted result, using only epoch and gradient of training MSE as stopping criteria. A slight variation on the width of the output interval, using sum of sample mean and standard deviation, also gave 3.04 x 10-4 MSE as best results. These intervals were found to perform well when set as constants, drawn from parametric statistical figures, around two times standard deviation of surface tension measurement differences from the experiment repetitions.
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