Up-Conversion Luminescence Processes in NaLaF4 Doped with Tm3+ and Yb3+ and Dependence on Tm3+ Concentration and Temperature

In this work, luminescence processes in polycrystalline NaLaF4:Tm3+ and NaLaF4:Tm3+,Yb3+ materials were studied. Luminescence spectra and decay kinetics measurements were performed for NaLaF4 doped with various Tm3+ concentrations (0.01, 0.1, 0.5, 1, and 2 mol%) under direct excitation to 3P0, 1D2, 1G4, and 3H4 states. It was found that some of the Tm3+ excited states are more affected by Tm3+ concentration than other states. Under infrared excitation of Yb3+, energy transfer to Tm3+ occurred and intensive ultraviolet and blue up-conversion luminescence was observed. Possible up-conversion mechanisms are discussed. Spectroscopic measurements show that long-duration excitation radiation reduces ultraviolet up-conversion luminescence intensity, and this intensity reduction is related to sample heating due to high excitation radiation density and a poor heat sink from samples. It was found that sample configuration for spectroscopic measurements is crucial to correctly describe measured up-conversion luminescence spectra.

Method for determining the degree of influence of the heating temperature on the strength set of concrete based on isotherms

The article presents the development of an alternative approach to determining the degree of influence of the curing temperature on the concrete strength gain, based on the construction of isotherms. Based on the test results, isotherms were plotted, representing the graphs of strength gain for each of the temperature regimes. Visual and numerical comparison of the concrete strength values obtained from isotherms gave an understanding of the degree of influence of sample heating on strength development.

Thermal Analysis of Paraffin-Embedded Tissue Blocks for Anatomic Pathology Processes

Goal: We analyze temperature dynamics in anatomic pathology samples to identify the most efficient refrigeration method and to predict the time available for an optimal sectioning before sample heating, thus to get appropriate information for a correct diagnosis by anatomopathologists. Methods: A thermal Finite Element (FE) analysis was carried out with COMSOL Multiphysics to evaluate temperature variations in paraffin-embedded tissues, i.e., muscle, bone and fat. Experiments with different tissues and thermocouple-based measurements allowed to validate the FE simulations. Results: Simulations allowed to estimate the time needed to bring the sample at the optimal temperature for sectioning (-8 - -4 °C) in different conditions: refrigeration on a cold plate, refrigeration in a cooled environment and refrigeration in an environment with a forced convection. Among the three cooling methods tested the last one resulted the most efficient. A cooling temperature of -20 °C was the most effective, among the ones tested. For the different conditions, the time needed for the surface of the tissue block to exit from a temperature corresponding to an optimal cutting, when leaving the sample expose to room temperature after refrigeration, ranged from 12s to 310 s. Conclusions: We quantify the time needed to adequately refrigerate paraffin-embedded tissue samples and the time available before they leave the optimal temperature window for sectioning. This information will be helpful in optimizing anatomic pathology processes.

MODELING OF PYROLYSIS OF OIL RESIDUES IN THE PRESENCE OF ALUMINOSILICATES

Данная работа посвящена изучению кинетики процесса каталитического пиролиза кубовых остатков нефти. Исследование проводилось методом термогравиметрии с различной скоростью нагрева образца (2,5; 5 и 10 К/мин). В качестве катализаторы была использована синтезированная каталитическая система: ZSM-5/бентонитовая глина с импрегнированным металлом (Со - 2 % масс.). При моделировании были определены формальные кинетические параметры Аррениуса процесса деструкции. Рассчитанная модель представляет собой двухстадийный параллельный процесс. Значения энергий активации деструкции для первой стадии составило 58 кДж/моль и 188 кДж/моль для второй. This work is devoted to the study of the kinetics of the process of catalytic pyrolysis of oil residues. The study was performed by thermogravimetry with different sample heating rates (2.5, 5, and 10 K / min). A synthesized catalytic system was used as a catalyst: ZSM-5 / bentonite clay with impregnated metal (Co-2% wt.). Formal kinetic parameters of the Arrhenius of the destruction process were determined During modeling. The calculated model is a two-stage parallel process. The destruction activation energies for the first stage were 58 kJ/mol and 188 kJ/mol for the second stage.

ANALISIS KARAKTERISASI XRD SINTESIS GADOLINIUM KARBONAT (Gd2(CO3)3@PEG DENGAN METODE SOLVOTERMAL

Abstrak Telah dilakukan sintesis partikel pegilasi gadolinium karbonat dengan metode solvotermal menggunakan prekursor polietilen glikol (PEG-1000) dan gadolinium asetat hidrat (Gd(CH3CO3)3) pada suhu 180oC dengan waktu pemanasan selama 3 jam, 5 jam, dan 7 Jam. Partikel pegilasi gadolinium karbonat (Gd2(CO3)3@PEG tersebut selanjutnya dianalisis pola difraksi dan bentuk struktur dengan menggunakan X-Ray Diffraction (XRD). Hasil karakterisasi spektrum XRD terhadap partikel Gd2(CO3)3 menunjukkan pila difraksi dengan posisi puncak-puncak difraksi bersesuaian dengan JCPDS No. 37-0559 dengan puncak utama pada 2θ = 11.75o. Pada waktu pemanasan 3 jam , sampel memiliki sifat amorf, sedangkan pada sampel waktu pemanasan 5 jam dan 7 jam sampel-sampel memiliki derajat kekristalan yang baik. Pada waktu pemanasan 5 jam lebih tinggi kristalisasinya daripada 7 jam yang mengindikasikan kualitas kristal lebih baik pada lama pemanasan 5 jam. Kata kunci : Gadolinium karbonat, metode solvotermal, PEG, XRD Abstract [Title: Analysis of XRD Characterization of Gadolinium Carbonate (Gd2 (CO3) 3 @ PEG Synthesis by Solvothermal Method] Synthesis of pegylated gadolinium carbonate particles by solvothermal method using polyethylene glycol (PEG-1000) and gadolinium acetate hydrate (Gd (CH3CO3) 3) precursors at 180oC with heating time for 3 hours, 5 hours and 7 hours. The gadolinium carbonate (Gd2 (CO3) 3 @ PEG particle pegylation was further analyzed by diffraction patterns and structural shapes using X-Ray Diffraction (XRD). The results of XRD spectrum characterization of Gd2 (CO3) 3 particles showed diffraction pila with diffraction peaks position. corresponds to JCPDS No. 37-0559 with the main peak at 2θ = 11.75 o At 3 hours of heating, the sample has amorphous properties, while the sample heating time is 5 hours and 7 hours the samples have a good degree of crystallization. 5 hours higher crystallization than 7 hours which indicates better crystal quality at 5 hours heating time. Keywords: Gadolinium carbonate, solvothermal method, PEG, XRD

Pembuatan Plastik Biodegradable Dari Pati Biji Nangka

Jackfruit seeds have not been widely used or thrown away as a waste. The content of jackfruit seeds in 100 gr contains 36,7 gr of carbohydrates, 4,2 gr of protein, 165 kcal of energy, so that it is used as food. Jackfruit seed starch isvery cheap even can bemade by itself simple. Relatively high starch contant of about 40-50%. The purpose of this research is to make biodegradable plastic from jackfruit seed starch with variation of glycerol addition, to know the result of biodegradable plastic from jackfruit seed starch. Method used in the study : making biodegradable plastic from jackfruit seed starch with variation of glycerol 2 ml, 3 ml dan 4ml. research was conducted by conducting water resistance test , melting poin test and biodegradable test. Results obtained from the research of making a better biodegradable plastic glycerol 2 ml because it can be seen plastik sheets of all smooth, thinner, clearer and transparent surfaces, no bubbles compared to other glycerol variations seen brownish. Water resistance test with the addition of 2 ml glycerol with the highest water endurance 91,67% with water absorption test using hot plate because the sample heating cannot melt perfectly and that can be observed only shrinkage. A biodegradable test 4 ml glycerol addition resulted a reduced percentage of residual weight of plastic increased by 78,57%.

Suhu Pemanas Sampel Optimal Untuk Klasifikasi Teh Hitam Menggunakan Electronic Nose

The optimization of heating temperature of black tea samples for the measurement of aroma with electronic nose (e-nose) has been successfully performed. Sample heating is done because black tea has a low aroma intensity and easily lost. However, the selection of such temperature should be selective because it can result in damage to the aroma of the sample. Therefore, temperature optimization needs to be done so that the resulting sensor response comes from the transformation of the undamaged aroma.The method used to obtain the optimum heating temperature by analyzing the sensor response of the aroma transformation that is captured by e-nose. Consistency and pattern changes formed from the sensor response are used as a comparison of optimal heating temperature selection. The measured sample varied in temperature (30 - 60 °C) so that the resulting sensor response was observed. Change in patterns indicate the aroma has been burning. After optimal temperature is obtained then black tea (50 gr) Broken Orange Pokoe, Broken Pokoe II and Bohea with a total sample of 300 bags were measured with e-nose. For further analysis, the result of classification by method of Principal Component Analysis (PCA) as proof of sample heating temperature optimization successfully done.The experimental results show optimal sample heating for black tea 3 quality 40 - 45 °C. After then with the third PCA the sample can be classified up to 92.5% of the total data variant. This indicates the aroma of tea is relatively constant and there is no pattern change.