Optimization Study of Preparation Eucalyptus Trees Activated Carbon for Removal of Methylene Blue Dye from Aqueous Solution

Mesoporous activated carbon were  prepared from eucalyptus trees stalks (ES) using physiochemical activation method, which  consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO2) gasification. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate preparation of the activated carbon with these variables. The effects of the activation temperature, activation time and chemical impregnation ratios on the carbon yield and methylene blue removal were investigated. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing activated carbon from eucalyptus stalks were found to be activation temperature of 650 oC, activation time of 0.5 h and chemical impregnation ratio of 2.5. The carbon yield was found to be 22.3% while the removal of methylene blue was found to be 89%. Keywords: Eucalyptus stalks; Optimization; Activated carbon; Adsorption; Methylene blue.

Multi-directional gated recurrent unit and convolutional neural network for load and energy forecasting: A novel hybridization

Energy operations and schedules are significantly impacted by load and energy forecasting systems. An effective system is a requirement for a sustainable and equitable environment. Additionally, a trustworthy forecasting management system enhances the resilience of power systems by cutting power and load-forecast flaws. However, due to the numerous inherent nonlinear properties of huge and diverse data, the classical statistical methodology cannot appropriately learn this non-linearity in data. Energy systems can appropriately evaluate data and regulate energy consumption because of advanced techniques. In comparison to machine learning, deep learning techniques have lately been used to predict energy consumption as well as to learn long-term dependencies. In this work, a fusion of novel multi-directional gated recurrent unit (MD-GRU) with convolutional neural network (CNN) using global average pooling (GAP) as hybridization is being proposed for load and energy forecasting. The spatial and temporal aspects, along with the high dimensionality of the data, are addressed by employing the capabilities of MD-GRU and CNN integration. The obtained results are compared to baseline algorithms including CNN, Long Short-Term Memory (LSTM), Bidirectional Long Short-Term Memory (Bi-LSTM), Gated Recurrent Unit (GRU), and Bidirectional Gated Recurrent Unit (Bi-GRU). The experimental findings indicate that the proposed approach surpasses conventional approaches in terms of accuracy, Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RSME).</p> </abstract&gt

Hydrodynamics and Kinetics of Phenols Removal from Industrial Wastewater in a Trickle Bed Reactor (Part I: Hydrodynamic Study)

An experimental investigation of the hydrodynamic parameters in a trickle bed reactor is presented. The operating conditions are selected for the operating system to be at trickle flow regime. The effects of the two-phase flow rates, reactor pressure and temperature on the pressure drop, external liquid holdup and liquid axial dispersion are discussed. Pressure drop was measured using differential pressure transducer, while liquid holdup and axial dispersion were estimated using RTD technique with a reactive dye as a tracer. The results confirmed that pressure drop is proportional to flow rate of fluids and operating pressure while it is inversely proportional to temperature. Liquid flow rate has a proportional effect on liquid holdup and axial dispersion while gas flow rate and temperature presented a different image. A comparison between the results of present work and that of literature is presented and discussed. Empirical correlations for pressure drop, liquid holdup and axial dispersion with operating conditions are developed with correlation coefficient of 98.4 to 99.7 %

Demonstration of GaN-on-silicon material system operating up to 3 kilovolts with reduced trapping effects

International audienceWe report on the first demonstration of low trapping effects up to 3000 V within GaN-on-silicon epitaxial layers using a local substrate removal (LSR) followed by a thick backside ultra-wide-bandgap AlN deposition. The fabricated AlGaN/GaN devices deliver low specific on-resistance below 10 mΩcm 2 together with unprecedented 3-terminal blocking voltage while substrate ramp measurements show reduced hysteresis up to 3000 V. These results pave the way for beyond 1200 V applications using large wafer diameter GaN-on-Si high electron mobility transistors

Magnetic studies of amorphous Fe-Dy-B ribbons

We have studied the magnetization of melt spun amorphous Fe80−xDyxB20 alloys with 0 ≤ x ≤ 7.5 under magnetic fields up to 6T, and have analyzed the results at 4.2 K on the basis of the random magnetic anisotropy model. Exchange constant and local random anisotropy KL were evaluated. Using the Sarkis´s model, the local anisotropies per atom are found to be 1.75 107 and 4 107 erg/cm3 for Fe and Dy, respectively.We have studied the magnetization of melt spun amorphous Fe80−xDyxB20 alloys with 0 ≤ x ≤ 7.5 under magnetic fields up to 6T, and have analyzed the results at 4.2 K on the basis of the random magnetic anisotropy model. Exchange constant and local random anisotropy KL were evaluated. Using the Sarkis´s model, the local anisotropies per atom are found to be 1.75 107 and 4 107 erg/cm3 for Fe and Dy, respectively

AlGaN/GaN High Electron Mobility Transistors with Ultra -Wide Bandgap AlN buffer

International audienc

Variación en parámetros bioquímicos en un grupo de pacientes con tumor cerebral primario: revisión de cuatro estudios

Introduction: It has been well established and evidence-based fact that serum levels of proteins, cholesterol, trace elements, andpseudouridines may suffer changes during a neoplastic disease process. This report encompassed four prospective studies, original in Iraq to our knowledge, had explored the serum total proteins (TP), pseudouridines levels, total serum cholesterol (TSC), and serum trace elements (TE), in groups of patients harboring primary brain tumours (PBT) compared to healthy persons. Patients and Methods:Study number 1: A group of 107 patients, from both sexes, aged 2-75 years, harboring PBT were admitted to and operated upon via formal craniotomy by staff neurosurgeons at The Teaching Hospital at Kadhimiyah (TTHK) and Neurosurgical Hospital (NH); their sera were tested for serum total proteins (TP); the latter biochemical parameters were compared with those of 40 healthy persons. Study number II: the same patients and healthy controls were tested for pseudouridine measurement. Study number III: Another group of 30 patients with PBT were studied for TSC levels and were compared with 30 healthy volunteers. Study number IV: A third group of 26 patients with PBT, from both sexes, their sera were tested and measured for TE; the measurements were compared to 1630 volunteers from both sexes and of different age groups. The sera and brain tumor tissue samples were analysed and examined by appropriate methods at relevant laboratories of the TTHK, NH, The Medical Research Centre (MRC) of The College of Medicine, Al-Nahrain University and the Iraqi Atomic Energy Committee (IAEC). Results and Discussion: The serum TP and PBT study: Results are shown in table 1. The serum pseudouridines and PBT study: Mean levels of pseudouridine in serum of PBT patients, were significantly higher (p < 0.01) than its levels in the (normal) controls, table 2. The TSC and PBT study: 1. Hesalthy persons from both sexes: age range, in years, 15 – 75, mean 40.5, SD ± 19.8; TSC range 142 – 230 mg / dl, mean 185.6 mg / dl, SD ± 24.9, (3.7 – 5.9 mmol / l, mean 4.8 mmol / l, SD± 0.6), table 3. 2. Thirty persons from both sexes having peripheral tumors, with no clinical evidence of brain tumors: age range, in years, 15 – 75, mean 54.3 ± 12.8; TSC range 90 – 220 mg / dl, 143 ± 36.3 (2.3 – 5.7 mmol / l, mean 3.7 ± 0.9), table 4. 3. Thirty patients from both sexes with primary and secondary brain tumors, age range, in years, 15 - 75, mean 41.3 ± 20.9; TSC range 140 – 284 mg / dl, 217.6 ± 41.2 (3.6 – 7.3 mmol / l, 5.6 ±1.1), table 4. Study number IV: Serum mean values (and S.D.) of all measured TEs were as follow: Se 0.045 +/- 0.011, Zn 0.320 +/- 0.095, Cu 0.607 +/- 0.154, Fe 0.880 +/- 0.456, Mg 13.625 +/- 3.994, Co 0.020 +/- 0.036, Ni 0.016 +/- 0.030, Mn 0.016 +/- 0.009, Cd 0.050 (one sample), and Cr 0.015 +/- 0.005 micrograms per milliliter (mcg / ml). All mean concentrations were consistently lower in the patients than healthy volunteers; both the Student’s (t) and probability (p value) tests were performed; for Se, Zn, Cu, Mg, Co, Ni, Mn, and Cr the p value was <0.01 showing statistically significant results; however, for Fe, though the mean concentration was also lower in the brain tumor group, there was no statistical significance, p > 0.05. Due to technical difficulties and very low concentration of Cd, it was not measured in healthy volunteers; however, it was measured in only one patient’s serum sample; this has been discarded from the study, table 5. Conclusions: Levels of serum TP, TC, and pseudouridine are higher in patients with PBT than in healthy people; however, those of serum TE are lower in the PBT group than healthy persons; the results of this report are in keeping with those of other researchers. The biochemical parameters can be an additional laboratory monitor in the investigation of PBT patients; however, both the specificity and sensitivity need to be ascertained. To our knowledge, this was the first study to be performed in Iraq in the setting of PB

Buffer breakdown in GaN-on-Si HEMTs: A comprehensive study based on a sequential growth experiment

Abstract The aim of this work is to investigate the breakdown mechanisms of the layers constituting the vertical buffer of GaN-on-Si HEMTs; in addition, for the first time we demonstrate that the breakdown field of the AlN nucleation layer grown on a silicon substrate is equal to 3.2 MV/cm and evaluate its temperature dependence. To this aim, three samples, obtained by stopping the epitaxial growth of a GaN on Silicon stack at different steps, are studied and compared: Si/AlN, Si/AlN/AlGaN, full vertical stack up to the Carbon doped buffer layer. The current-voltage (IV) characterizations performed at both room temperature and high temperature show that: (i) the defectiveness of the AlN nucleation layer is the root cause of the leakage through an AlN/Silicon junction, and causes the vertical I-V characteristics to have a high device-to-device variability; (ii) the first AlGaN layer grown over the AlN, beside improving the breakdown voltage of the whole structure, causes the leakage current to be more stable and uniform across the sample area; (iii) a thick strain-relief stack and a carbon-doped GaN buffer enhance the breakdown voltage up to more than 750 V at 170 °C, and guarantee a remarkably low device-to-device variability. Furthermore, a set of constant voltage stress on the Si/AlN sample demonstrate that the aluminum nitride layer shows a time dependent breakdown, with Weibull-distributed failures and a shape factor greater than 1, in line with the percolation model