KINETIKA OTAPANJA UZORKA RUDE BAKRENOG OKSIDA I OPTIMIZACIJA PARAMETARA UTJECAJA POMOĆU METODOLOGIJE ODZIVNE POVRŠINE

In this research work, the leaching behavior of a copper oxide ore sample prepared from the Qaleh-Zari copper mine with a very high grade of 5.4% Cu (malachite and azurite) was investigated to evaluate the effects of significant operating parameters on copper recovery, including sulfuric acid concentration, solid percentage, particle size and agitation speed. Then, response surface methodology (RSM) and central composite design (CCD) were employed to optimize the leaching process and assess interactions between the effective parameters. In order to further analyze the leaching behavior, kinetics of copper dissolution was studied on the basis of the shrinking core models (SCM). The results showed a reduction in the rate of recovery with an increase in the solid percentage and/or particle size. In contrast, any increase in the agitation speed and/or acid concentration was found to improve the recovery. It was remarkable that increasing the sulfuric acid content, beyond a certain level, imposed no significant effect on the recovery. Optimal copper recovery was obtained with a solid percentage, agitation speed, particle size, and sulfuric acid concentration of 25.12%, 586 rpm, 70 μm, and 12.5%, respectively, leading to a recovery of 93.24%. A study on the leaching kinetics indicated that the dissolution rate was controlled by the fluid diffusion from product layer model with 30.71 kJ/mol of activation energy.U radu se istražuje izluživanje uzorka rude bakrenog oksida iz rudnika bakra Qaleh-Zari s vrlo visokim udjelom Cu od 5,4% (malahit i azurit), kako bi se procijenili utjecaji značajnih parametara na stupanj iskorištenja rude, uključujući koncentraciju sumporne kiseline, sadržaj čvrstog, veličinu čestica i brzinu miješanja. Zatim su korišteni metodologija odzivne površine (eng. RSM) i centralno kompozitni plan (eng. CCD) za optimizaciju procesa izluživanja i procjenu međudjelovanja parametara. Kako bi se dodatno analiziralo izluživanje, proučavana je kinetika otapanja bakra na temelju modela jezgre (eng. SCM). Rezultati su pokazali smanjenje iskorištenja rude s povećanjem udjela čvrstih čestica i/ili veličine čestica. Nasuprot tome, utvrđeno je da svako povećanje brzine miješanja i/ili koncentracije kiseline povećava iskorištenje. Zanimljivo je da povećanje sadržaja sumporne kiseline iznad određene razine nije imalo značajan učinak na iskorištenje. Optimalno izluživanje bakra dobiveno je s udjelom čestica 25,12%, brzinom agitacije 586 okretaja u minuti, veličinom čestica 70 μm i koncentracijom sumporne kiseline od 12,5%. Ispitivanje kinetike izluživanja pokazuje da je brzina otapanja kontrolirana difuzijom tekućine prema modelu slojeva uz energiju aktivacije 30,71 kJ/mol

The Impact of Load Altering Attacks on Distribution Systems with ZIP Loads

Load-altering attacks (LAAs) pose a significant threat to power systems with Internet of Things (IoT)-controllable load devices. This research examines the detrimental impact of LAAs on the voltage profile of distribution systems, taking into account the realistic load model with constant impedance Z, constant current I, and constant power P (ZIP). We derive closed-form expressions for computing the voltages of buses following LAA by making approximations to the power flow as well as the load model. We also characterize the minimum number of devices to be manipulated in order to cause voltage safety violations in the system. We conduct extensive simulations using the IEEE-33 bus system to verify the accuracy of the proposed approximations and highlight the difference between the attack impacts while considering constant power and the ZIP load model (which is more representative of real-world loads)

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

Knowledge transfer-oriented deep neural network framework for estimation and forecasting the state of health of the Lithium-ion batteries

This paper proposes an efficient data-driven framework for estimating and forecasting the state of health (SOH) of Lithium-ion (Li-ion) batteries. The proposed framework is established upon a deep neural network (DNN) model, knowledge transfer asset, and autoregressive integrated moving average (ARIMA) forecasting model. The knowledge transfer property reduces the required data for training the model and hence the approach becomes fast and good fit for forecasting the SOH of Li-ion batteries. Among various possibilities, the most efficient training features are picked by Pearson correlation coefficient and least absolute shrinkage and selection operator (LASSO) regression. To suppress existing noises, Savitzky-Golay filter is applied to the signals. The proposed framework allows to use a limited portion of the dataset (about 25 %) for training phase and guarantees high accuracy (almost 96 %) of estimation according to coefficient of determination. Mean squared error (MSE) of the estimations is 0.00075 which is small enough to trust on results. MSE of the model not only during training via 25 % of data is measured, but also after training by 20 % and 30 % of dataset is calculated as well. Training by 20 % of dataset results in a great downfall in the model performance with a 26.6 % rise in the MSE value. Surprisingly, training the model with 30 % portion of the dataset does not add any noticeable accuracy to the model. This study confirms that the transfer learning property and DNN model combination could achieve a dramatic reduction of the dataset portion for training purpose

Study of the cellular senescence process in human umbilical cord Wharton's jelly-derived mesenchymal stem cells

Introduction: Embryonic stem cells are candidates for the treatment of regenerative medicine, but their use is faced with limitations due to ethical issues. The human umbilical cord-derived mesenchymal stem cells (MSCs) are appropriate options because the cells have no ethical difficulties and have self-renewal. Senescence is known as a gradual functional loss that heterogeneously occurs in multiple organ systems. Objective: The objective of this study was to investigate the cellular senescence process in human umbilical cord Wharton's jelly-derived mesenchymal cells. Materials and Methods: Umbilical cord was obtained from healthy newborns at the General Hospital of Tabriz. Under sterile conditions, Wharton's jelly was removed from the blood vessels and minced into small pieces of about 0.5 mm. These were cultured in Dulbecco's Modified Eagle's Medium (MSC medium). Real-time polymerase chain reaction for p16INK4a and senescence-associated β-galactosidase (SA-β-gal) staining was performed to investigate the cellular senescence process. Results: The results showed the different expressions in the different passages, but it was significantly increased from the fifth passage compared to the first passage. SA-β-gal staining also showed increased colour intensity in the fifth passage compared to the first passage. Conclusion: SA-β-gal is not a specific marker for senescence, while p16INK4a is a specific marker. Further studies are required for the investigation of the senescence mechanism, such as the evaluation of genes involved in the senescence

Isolation and Molecular Identification of Streptomyces spp. with Antibacterial Activity from Northwest of Iran

Introduction: Streptomyces are a group of prokaryotes that are usually found in all types of ecosystems including water and soil. This group of bacteria is noteworthy as antibiotic producers; so the isolation and characterization of new species seemed to be crucial in introduction of markedly favorable antibiotics. Therefore, in this study we aim to isolate and characterize novel strains of Streptomyces with high antibiotic production capability. Methods: To achieve this goal, from 140 isolates collected throughout northwest of Iran, 12 selected Streptomyces isolates which exhibited high antibacterial activity against pathogenic bacteria were subjected to PCR reaction for identification via 16S rDNA gene and random amplified polymorphic DNA (RAPD) pattern analysis. Results: Analysis of morphological and biochemical characteristics and the 16S rDNA gene sequence indicated that all 12 selected isolates belonged to the genus Streptomyces. Moreover, screening of the isolates with regard to their antimicrobial activity against indicator bacteria as well as their classification using RAPD analysis revealed that G614C1 and K36C5 isolates have considerable antimicrobial activity and high similarity to Streptomyces coelicolor and Sreptomyces albogriseolus, respectively. Conclusion: Since many isolates in this study showed inhibitory effects against pathogenic bacteria, soil of northwest of Iran could be used as a rich source to be explored for novel Streptomyces strains with high potency of antibiotic production

Optimal placement and power supply of distributed generation to minimize power losses

An increasing number of renewable energy-based distribution generation (DG) units are being deployed in electric distribution systems. Therefore, it is of paramount importance to optimize the installation locations as well as the power supply of these DGs. The placement of DGs in the grid can decrease the total distance that power is transmitted and thus reduce power losses. Additionally, the reactive power supply from the DGs can further reduce power losses in the distribution grid and improve power transmission efficiency. This paper presents a two-stage optimization strategy to minimize power losses. In the first stage, the DG locations and active power supply that minimize the power losses are determined. The second optimization stage identifies the optimal reactive power output of the DGs according to different load demands. The proposed approach is tested on the IEEE 15-bus and the IEEE 33-bus systems using DIgSILENT PowerFactory. The results show that the optimized power losses can be reduced from 58.77 kW to 3.6 kW in the 15 -bus system, and from 179.46 kW to around 5 kW in the 33 -bus system. Moreover, with the proposed optimization strategy, voltage profiles can be maintained at nominal values enabling the distribution grid to support higher load demand

A Game-Theoretic Approach for PMU Deployment Against False Data Injection Attacks

International audiencePhasor Measurement Units (PMUs) are used in the measurement, control and protection of power grids. However, deploying PMUs at every bus in a power system is prohibitively expensive, necessitating their optimal placement to ensure the system observability with minimum cost. This partial PMU placement renders the system vulnerable to False Data Injection Attacks (FDIAs). This paper proposes a zero-sum game-based approach to strategically place an additional PMU (after the initial optimal PMU deployment for full observability) to bolster robustness against FDIAs by introducing redundancy in attack-susceptible areas. To compute the Nash equilibrium (NE) solution, we leverage a reinforcement learning algorithm that mitigates the need for complete knowledge of the opponent's actions. The proposed PMU deployment algorithm increases the detection rate of FDIA by 36% compared to benchmark approaches

OPTIMIZACIJA FLOTACIJE UZORAKA OKSIDIRANE RUDE BAKRA RUDNIKA QALEH ZARI SEKVENCIJALNIM PRISTUPOM SULFIDACIJE KORIŠTENJEM METODOLOGIJE ODZIVNE POVRŠINE

One of the main challenges in the copper oxide processing industry is the application of flotation to reduce operating costs. Sulfidation-flotation is a commonly employed approach for floating oxide minerals using sulfidizers in order to sulfide the mineral’s surface. In this research work, an oxidized sample from the Qaleh Zari copper mine was used which was a high grade with 5.4% of copper (malachite and azurite). The prepared sample was subjected to mineralogical studies, and the obtained results indicated that the sample was oxidized. Malachite and azurite were the predominant minerals of copper oxide, and the predominant waste minerals were quartz and iron oxides (hematite and magnetite). The addition of sodium sulfide and flotation in four consecutive steps was a successful approach to meet the proper recovery and grade. Sodium sulfide, amyl potassium xanthate, sodium sulfide preparation time, and pH were selected as operating parameters using a central composite design (CCD). Also, by measuring the zeta potential, the electric charge of malachite was determined in different conditions after adding chemicals. Finally, under optimal conditions, the consumptions of sodium sulfide and amyl potassium xanthate, sodium sulfide preparation time, and pH value were 6790 g/t, 736 g/t, 10 minutes, and 9, respectively. By applying the mentioned conditions, a concentrate with a grade of 22.13%Cu and 90.51% recovery was achieved.U industriji oplemenjivanja odnosno prerade oksida bakra jedan od najvećih izazova jest smanjivanje operativnih troškova primjenom flotacije. Uobičajeno se u flotaciji oksidnih minerala površina minerala aktivira postupkom sulfidizacije. U ovome radu provedeno je istraživanje flotacije na uzorku oksidirane rude iz rudnika bakra Qalej Zari koja sadržava 5,4 % bakra (malahit i azurit). Pripremljeni uzorak podvrgnut je mineraloškim istraživanjima, a dobiveni rezultati pokazali su da je uzorak oksidiran. Od bakrovih oksida prevladavali su minerali malahit i azurit, a od jalovinskih minerala kvarc i željezni oksidi (hematit i magnetit). Aktivacija dodavanjem natrijeva sulfida te flotacija u četiri uzastopna koraka pokazali su se kao uspješan pristup za postizanje odgovarajućega iskorištenja i kvalitete. Za dizajn eksperimenta odabran je centralni kompozitni dizajn (CCD) s radnim parametrima: potrošnja aktivatora (natrijev sulfid), potrošnja kolektora (amilov kalijev ksantat), vrijeme aktivacije i pH. Također, mjerenjem zeta-potencijala određen je električni naboj malahita u različitim uvjetima nakon dodavanja kemikalija. Zaključno, u optimalnim uvjetima parametri su bili: potrošnja natrijeva sulfida 6790 g/t, amilova kalijeva ksantata 736 g/t, vrijeme aktivacije 10 minuta i pH vrijednost 9. Primjenom navedenih uvjeta dobiven je koncentrat sadržaja 22,13 % Cu i iskorištenja korisne komponente u koncentratu od 90,51 %