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1

Lightweight hybrid cryptography algorithm for wireless body area sensor networks using cipher technique

Raziq Aizaz, Qureshi Kashif Naseer, Yar Asfand, Ghafoori Kayhan Zrar, Jeon Gwanggil

Computer Assisted Methods in Engineering and Science

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2024

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Vol. 31, no. 2

213--240

EN

Wireless Body Area Networks (WBANs) are based on connected and dedicated sensor nodes for patient monitoring in the healthcare sector. The sensor nodes are implanted inside or outside the patient’s body for sensing the vital signs and transmitting the sensed data to the end devices for decision-making. These sensor nodes use advanced communication technologies for data communication. However, they have limited capabilities in terms of computation power, battery life, storage, and memory, and these constraints make networks more vulnerable to security breaches and routing challenges. Important and sensitive information is exchanged over an unsecured channel in the network. Several devices are involved in handling the data in WBANs, including sink nodes, coordinator, or gateway nodes. Many cryptographic schemes have been introduced to ensure security in WBANs by using traditional confidentiality and key-sharing strategies. However, these techniques are not suitable for limited resource-based sensor nodes. In this paper, we propose a Lightweight Hybrid Cryptography Algorithm (LWHCA) that uses cryptographicbased techniques for WBAN networks to improve network security, minimize network overhead and delay issues, and improve the healthcare monitoring processes. The proposed solution is evaluated in a simulation scenario and compared with state-of-the-art schemes in terms of energy consumption, and ciphertext size.

2

Separation and purification of light rare earth elements from chloride media using P204 and Cyanex272 in sulfonated kerosene under non-saponification conditions

Fan Peiqiang, Zhang Wenjie, Tong Xiong, Xie Xian, Xie Ruiqi, Song Qiang, Du Yunpeng, Cao Yang

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 172444

EN

The extraction of light rare earths (Pr and Nd) from chloride medium was investigated using a mixture of di(2-ethylhexyl) phosphoric acid (P204) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272) in sulfonated kerosene. The P204+Cyanex272 system exerted a synergistic effect on the separation of light rare earths, and the separation coefficient was higher than when P204 and Cyanex272 were used as extractants alone. The separation coefficient of Pr and Nd in the extraction system reached 1.75 when the pH of the aqueous phase material solution was approximately 2.5, and 1.5 mol/L hydrochloric acid as a stripping agent effectively eluted the rare earth ions in the loaded organic phase. Combining the slope method, infrared spectroscopy, and nuclear magnetic resonance spectroscopy, we explored the mechanism of the extracted Nd and Pr into the organic phase complex, and finally entered the organic phase with Re(HA2)2B. The P-O-H bond and P=O bond in the extractant P204 and Cyanex272 formed a coordination bond with Re3+. Therefore, this extraction method also provides a reference for a more environmentally friendly and efficient procedure for separation and purification of light rare earth elements Pr and Nd.

3

Counterion effects on the alkali dissolution mechanism of quartz

Yao Yu-yun, Tang Yun, Yang Yong, Li Guo-hui, Wu Bo, Dai Wen-zhi

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 160038

EN

In gold ore, quartz plays an important role in mineral formation by acting as the follower. Understanding counterion release, transport, and deposition in alkali solution is a prerequisite for evaluating the potential role of gold separate from quartz deposits in pretreatment. In this work, the aggregation, retention, and release of counterion in alkali solution media were investigated by kinetic research and pure mineral experiments, the correlation and mechanism of these processes were revealed by combining geochemical theory, interaction energy calculation, and quantum chemistry. The results showed that the retention and release of counterion were closely related to the dissolution and corrosion rate of quartz. The NH4+ and Fe2+ with higher mineral affinity reduced the quartz stability, and the dispersion stability and mobility of the quartz were greatly improved by an alkaline substance due to the enhancement of steric hindrance effects. Quantum chemical calculation results show that ammonium ion promotes the dissolution of quartz stronger than ferrous ion, which is mainly reflected in reducing the activation energy required for the formation of transition state (TS1), which can be verified by kinetic calculation. These findings provide essential insight into the extraction of gold coated by quartz as well as a vital reference for the experiment of gold-loaded quartz leaching in mineral processing.

4

A review of the application of nanoparticles as collectors in ion flotation

Sobouti Arash, Rezai Bahram, Hoseinian Fatemeh Sadat

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 176040

EN

Ion flotation is one of the most promising and unique methods for reducing or removing toxic heavy metal ions, organic pollutants, or inorganic anions and cations from mining and metallurgical wastewater. It is a cost-effective and convenient method. In ion flotation, surface-active ions are removed from aqueous solutions by adding surfactants. Therefore, the main purpose of this review article was to summarize the application of various surfactants (nanoparticle surfactants, chemical synthetic surfactants, and biosurfactants) used in ion flotation. Then, the advantages, disadvantages, and prospects of surfactants were comprehensively discussed. Recent progress regarding nanoparticle surfactants in ion flotation and the mechanism of colligends binding with nanoparticles were evaluated.

5

Computer-simulated degradation of CF3Cl, CF2Cl2, and CFCl3 under electron beam irradiation

Kabasa Stephen, Sun Yongxia, Chmielewski Andrzej G., Nichipor Henrietta

Nukleonika

|

2023

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Vol. 68, No. 3

67--76

EN

Electron beam treatment technologies should be versatile in the removal of chlorofl uorocarbons (CFCs) owing to their exceptional cross sections for the thermal electrons generated in the radiolysis of air. Humidity, dose rates, O2 concentration, and CFC concentration infl uence the effi ciency of the destruction process under electron beam treatment. Computer simulations have been used to theoretically demonstrate the destruction of chlorotrifl uoromethane (CF3Cl), dichlorodifl uoromethane (CF2Cl2), and trichlorofl uoromethane (CFCl3) in the air (N2 + O2: 80% + 20%) in room temperature up to a dose of 13 kGy. Under these conditions, it is predicted that the removal effi ciency is in the order CF3Cl (0.1%) < CF2Cl2 (7%) < CFCl3 (34%), which shows the dependence of the process on the number of substituted Cl atoms. Dissociative electron attachment with the release of Cl– is the primary process initiating the destruction of CFCs from the air stream. Reactions with the first excited state of oxygen, namely, O(1 D), and charge-transfer reactions further promote the degradation process. The degradation products can be further degraded to CO2, Cl2, and F2 by prolonged radiation treatment. Other predicted products can also be removed through chemical processes.

6

Developing a work roll model by analyzing the mechanism influence through analytic calculation

Al Mohammed Hussein Mohammed Ali

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 4

1--9

EN

This paper presents a novel approach to developing a work roll prediction model that takes into account both the mechanism and condition influences on work roll wear. This was accomplished by conducting an analytic calculation of work roll mechanism influence, constructing a work roll wear model, and combining the wear mechanism with actual wear data. The resulting model is applicable to both symmetric and asymmetric wear of the work roll, and experimental results showed that the relative error between measured and predicted values was less than 5%, with a maximum error of below 15%. This level of accuracy is sufficient for predicting roll wear and lays the foundation for improved strip shape control and roll design. Furthermore, this approach has the potential to generate significant economic benefits and has wide-ranging applications.

7

Experimental study of lignite structure evolution characteristics and mechanisms under thermal-mechanical co-function

Yu Weidong

Archives of Mining Sciences

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2023

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Vol. 68, no. 4

671--684

EN

In-situ thermal upgrading modification technology is of great significance to lignite utilisation cleanly. It is an extremely complex multi-field coupling process. Therefore, it is necessary to study the physical properties of lignite under the thermo-mechanical coupling function. In this paper, the lignite pore evolution characteristics under thermal-mechanical co-function have been obtained at different scales based on experimental results. The mechanisms also have been deeply studied. The results indicated that lignite total porosity first increased and then decreased as the temperature increased from 23°C to 400°C under the triaxial stress of 7 MPa. The maximum value of 21.64% for the total porosity of lignite was observed at 200°C. Macropores were dominant when the temperature was lower than 100°C, while visible pores were dominant when at temperatures ranging from 100~400°C. The thermal weight loss and deformation characteristics of lignite were further studied using a thermal-mechanical testing platform. The weight loss and deformation process could be divided into three stages, namely the slow, rapid, and relatively slow stages. After being continuously pyrolysed for 5 hours at a temperature of 400°C, the maximum weight loss rate of lignite was 52.38%, the maximum axial linear strain was 11.12%, and the maximum irrecoverable radial strain was 18.79%. The maximum axial thermal deformation coefficient of lignite was −2.63×10 −4℃ −1 at a temperature of 289°C. Macro-deformation and component loss were the main mechanisms of lignite structure evolution.

8

The influence of chlorine substitution on the adsorption of chlorophenols on HDTMA-modified halloysite in aqueous solutions

Szczepanik Beata, Kołbus Anna, Słomkiewicz Piotr, Czaplicka Marianna

Archives of Environmental Protection

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2023

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Vol. 49, no 2

66--75

EN

This article focuses on discussing the adsorption process of phenol and its chloro-derivatives on the HDTMA-modified halloysite. Optimized chemical structures of phenol, 2-, 3-, 4-chlorophenol, 2,4-dichloro-, and 2,4,6-trichlorophenol were obtained with computational calculation (the Scigress program). Charge distributions and the hypothetical structure of the system HDTMA-modified halloysite are among their key features. The above-mentioned calculations are applied in order to explain adsorption mechanism details of chlorophenols on the HDTMA-modified halloysite in aqueous solutions. The results of electron density distribution and solvent accessible surface area calculations for phenol and chlorophenols molecules illustrate the impact of chlorine substitution position in a phenol molecule, both on the mechanism and the kinetics of their adsorption in aqueous solutions. Experimental adsorption data were sufficiently represented using the Langmuir multi-center adsorption model for all adsorbates. In addition, the relations between adsorption isotherm parameters and the adsorbate properties were discussed. This study also targets at explaining the role of meta position as a chlorine substituent for mono-chloro derivatives. Given the above findings, two possible mechanisms were utilized as regards chlorophenol adsorption on the HDTMA-modified halloysite, i.e., electrostatic and partition interactions when the chlorophenols exist in a molecular form.

9

Robot grasping and regrasping kinematics using Lie algebra, the geodesic, and Riemann curvature tensor

Sahin Haydar

Archives of Control Sciences

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2023

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Vol. 33, No. 1

5--23

EN

Differential geometry is a strong and highly effective mathematical subject for robot gripper design when grasping within the predetermined trajectories of path planning. This study in grasping focuses on differential geometry analysis utilizing the Lie algebra, geodesic, and Riemann Curvature Tensors (RCT). The novelty of this article for 2RR robot mechanisms lies in the approach of the body coordinate with the geodesic and RCT. The importance of this research is significant especially in grasping and regrasping objects with varied shapes. In this article, the types of workspaces are clarified and classified for grasping and regrasping kinematics. The regrasp has not been sufficiently investigated of body coordinate systems in Lie algebra. The reason for this is the difficulty in understanding relative coordinates in Lie algebra via the body coordinate system. The complexity of the equations has not allowed many researchers to overcome this challenge. The symbolic mathematics toolbox in the Maxima, on the other hand, aided in the systematic formulation of the workspaces in Lie algebra with geodesic and RCT. The Lie algebra se(3) equations presented here have already been developed for robot kinematics from many references. These equations will be used to derive the following workspace types for grasping and regrasping. Body coordinate workspace, spatial coordinate workspace with constraints, body coordinate workspace with constraints, spatial coordinate workspace with constraints are the workspace types. The RCT and geodesic solutions exploit these four fundamental workspace equations derived using Lie algebra.

10

The removal efficiency and reaction mechanism of the aluminum coagulant on phenolic compounds in the presence of hardness salts

Hecini Lynda, Boukerker Hassen, Kherifi Wahida, Mellah Abdelkarim, Achour Samia

Journal of Water and Land Development

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2022

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no. 54

225--233

EN

This study is the evaluation of the coagulation efficiency of the aluminum sulfate on the removal of catechol and pyrogallol. The study has focused on the impact of inorganic components of hardness Algerian waters. Jar-test trials were conducted on the two phenolic compounds dissolved in distilled water only, which was later enriched with minerals. Several reaction parameters varied, including the effect of pH and the influence of the salt content, and this approach yielded a better understanding of interaction between phenolic compounds and calcium/magnesium salts. The results indicate that the process efficiency depends on the number and position of OH in molecules. The main mechanisms would be either a physical adsorption, an exchange of ligand, or complexation on the floc surface of aluminum hydroxide. Moreover, the addition of inorganic salts appears to improve removal efficiency of tested phenolic compounds and have an effect on the optimal pH range for coagulation.

11

Comparative Adsorption of Methylene Blue Dye on Hexane-Washed and Xanthated Spent Grated Coconut (Cocos nucifera L.): Isotherms, Thermodynamics, and Mechanisms

Khalid Khadijah, Hanafiah Megat Ahmad Kamal Megat, Al-Amrani Waheeba A., Malek Nik Ahmad Nizam Nik, Fatinathan Sharon

Journal of Ecological Engineering

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2022

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Vol. 23, nr 3

1--11

EN

A batch system investigated the application of two types of chemically modified biosorbents derived from spent grated coconut (Cocos nucifera) powder to adsorb methylene blue (MB) from aqueous solutions. The biosorbents were characterised by spectroscopic and quantitative analyses. The assessment of MB adsorption onto the investigated biosorbents was studied at different experimental conditions with different pHs (2–9) and different initial concentrations of MB (10–400 mg/L) at three different temperatures (298, 308, and 318 K). The maximum adsorption capacity (qmax) of xanthated spent grated coconut (XSGC) was higher than that of hexane-washed spent grated coconut (HSGC). The thermodynamic study indicated that the MB adsorption process was spontaneous for both biosorbents. Desorption of MB-loaded biosorbents was carried out using HCl, NaOH, and Na2EDTA solutions. A desorption ratio of more than 90% was obtained over three adsorption/desorption cycles for HSGC. However, XSGC demonstrated poor MB desorption, implying a stronger MB interaction with XSGC, which could be attributed to H-bonding, Yoshida H-bonding, n-π, and π-π bonding. The study showed that HSGC and XSGC could be applied as biosorbents to remove low MB concentrations from aqueous solutions.

12

Lightweight Security Mechanism to Mitigate Active Attacks in a Mobile Ad-hoc Network

Ahamed Uthumansa, Fernando Shantha

International Journal of Electronics and Telecommunications

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2022

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Vol. 68, No. 1

145--152

EN

Mobile Ad hoc Network (MANET) is a type of Ad hoc network. General properties of MANET open the network to various security threats. Network layer-based Active attacks are widespread and destructive. Available security solutions contain complex calculations. Therefore, the objective of this research is to propose a lightweight security mechanism to enhance the security of data communications between source and destination nodes in a MANET from network layer-based active attack. Blackhole is used as a network layer-based Active attack. The network performance is evaluated using Packet Delivery Ratio (PDR), Average End-to-End Delay (AEED), Throughput, and Simulation Processing Time at Intermediate Nodes (SPTIN). The controller network was used to compare the performance of each network. During the experiment due to the impact of the blackhole attack, compared to the controller network, the PDR was found to be 0.28%, AEED was infinity and Throughput was 0.33%. The performance of the proposed security mechanism was compared with that of the controller network, and the values of PDR, AEED, Throughput, and SPTIN were found to be 98.0825%, 100.9346%, 99.9988%, and 96.5660%, respectively. The data packet delivery ratio was 100.00% compared to that of the controller network. The network that was affected by a blackhole attack showed a higher amount of ADDR than the controller network and the lowest amount of PDR. The network that was affected by the blackhole showed underperformance compared to the controller network. The proposed security mechanism performs well in PDR, AEED, and Throughput compared to the controller network. The AEED and SPTIN values prove that the proposed solution is free from complex calculations. The scope of the solution can be expanded into a lightweight Intruder Detection System to handle different types of security attacks in MANETs.

13

Fundamental study of the photocatalytic reduction of CO2: A short review of thermodynamics, kinetics and mechanisms

Gandhi Romil, Moses Aashish, Baral Saroj Sundar

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

223-–228

EN

On the off chance that methods which reduce the global CO2 content are unavailable and inefficient, the increasing CO2 levels will lead to a synchronized rise in temperature across the world. The conversion of this abundant CO2 into hydrocarbons like CH4, CH3OH, CO, HCOOH and hydrogen fuel using different techniques and their use for power could assist with the world’s energy deficiency and solve the CO2 reduction-energy nexus. In this study, photocatalytic CO2 conversion by sunlight will be of primary focus since this bears a resemblance with the regular photosynthesis phenomenon. This work also portrays the writings that have narrated the development of mixtures of two or more carbon ions (C2 ̧) within the photocatalytic reduction of CO2. This paper thus comprises the energy required for CO2 photoreduction, the kinetics mechanisms and thermodynamics requirements. The reaction of CO with water and the hydrogenation of CO2 are covered to understand the gap of Gibb’s free energy between both of the reactions. Likewise, the summary of different metal-based co-catalysts, metal-free co-catalysts and their selectivity towards CO2 reduction by photocatalysis and reduction of CO2 into various hydrocarbons, fuel and materials have also been examined.

14

The durability of concrete subject to mechanical load coupled with freeze–thaw cycles: a review

Xu Yanqun, Ye Hansong, Yuan Qiang, Shi Caijun, Gao Yun, Fu Qiang

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e47, 2022

EN

In cold regions, concrete structures are often subject to the coupled effect of mechanical loading with freeze–thaw (F–T) cycles, which results in a reduced service life. In this paper, the state of the art and challenges regarding the durability of concrete subjected to mechanical loading coupled with F–T cycles are reviewed in depth. The experimental setups used to simulate the coupled effect of mechanical loading with F–T cycles were summarized first, including the shapes of the specimens, operation methods, advantages, and limitations. Subsequently, relevant research methods such as numerical simulation methods and damage characterization methods were presented. Afterward, special attention was dedicated to the mechanism elaboration and performance improvement of the concrete subject to the coupled effect. Finally, some thoughts on potential directions for future work were discussed.

15

Mechanism of the oxidation of nitric oxide with oxygen

Głowiński Józef, Hoffmann Józef, Wilk Marcin

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 1

31--36

EN

Very fast reactions of forming higher nitrogen oxides set out an equilibrium framework for the course of the reaction of nitrogen monoxide oxidation. The slow course of reaction of nitrogen monoxide with oxygen permanently violates the created equilibria. In particular, the equilibrium of the oxidation reaction of nitrogen monoxide with nitrogen dioxide. The contribution of this reaction to the transformation of nitrogen monoxide in the conditions of nitrogen trioxide removal from the gas phase was estimated.

16

New insights into the promotion mechanism of (NH4)2SO4 in sulfidization flotation: a combined experimental and computational study

Chen Daixiong, Liu Mengfei, Hu Bo, Dong Yanhong, Xue Wei, He Peng, Chen Fang, Zhu Jianyu, Zhang Chenyang

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 5

57--70

EN

Ammonium sulfate ((NH4)2SO4) exhibits promoting effects in malachite sulfidization flotation. However, the promotion mechanism remains poorly understood. In this study, micro-flotation tests, zeta-potential measurements, scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and materials studio simulation (DFT) were used to investigated the promotion mechanism of (NH4)2SO4. Micro-flotation test demonstrates that the recovery of malachite from 73% increased to 83%, when the (NH4)2SO4 was added. Contact angle and zeta potential test results indicate that addition of Na2S•9H2O changes the surface properties of malachite and provide the conditions for adsorption of butyl xanthate (BX). After promoting the sulfidization by (NH4)2SO4, BX is more effective in improving the hydrophobicity. SEM-EDS and AFM results show that (NH4)2SO4 can improve performance and stability of sulfidization. X-ray photoelectron spectroscopy indicates that after sulfidization, polysulfides and cuprous were appeared in malachite surface, infers that a redox reaction occurs between sulfur and copper on the surface of malachite. After addition of (NH4)2SO4, the percentage of polysulfides and cuprous were increased, it implies (NH4)2SO4 can accelerate the redox reaction. Computational results show that after adding (NH4)2SO4, the adsorption energy of HS- on the malachite surface is reduced, implies that (NH4)2SO4 can improve the stability of HS-adsorption on the surface of malachite.

17

Experimental Insight into the Catalytic Mechanism of MFe2O4 (M = Ni, Zn and Co) on the Thermal Decomposition of TKX-50

Hou Xiaoting, Zhang Ming, Zhao Fengqi, Yang Yanjing, An Ting, Li Hui, Pan Qing, Wang Xiaohong, Zhang Kun

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 2

223--244

EN

Synthesized dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (TKX-50) owes its outstanding application prospects in the field of insensitive solid propellants not only to its high energetic performance but also to its low mechanical sensitivity. Based on the excellent catalytic activity of bimetallic iron oxides for the thermal decomposition of TKX-50, the catalytic mechanism of bimetallic iron oxides (NiFe2O4, ZnFe2O4 and CoFe2O4) for TKX-50 pyrolysis has been explored. For this study, the decomposition process of TKX-50, before and after mixing with the bimetallic iron oxides NiFe2O4, ZnFe2O4 and CoFe2O4 was monitored by in-situ FTIR and gas-phase MS-FTIR instruments. Of the different catalysts, ZnFe2O4 gave the best result for reducing the initial decomposition temperature of TKX-50. Additionally, the activation energy of functional group cleavage of TKX-50, before and after mixing with ZnFe2O4, was also calculated for mechanism analysis from the results of the in-situ FTIR measurements. The results showed that the condensate and the gas-phase decomposition products of TKX-50 remained unchanged after mixing with different catalysts, while the activation energy of tetrazole ring cleavage was significantly reduced. The results of this study will be helpful for the rational design of insensitive solid propellant formulations containing TKX-50, and for understanding the pyrolysis mechanisms of TKX-50 before and after mixing with the efficient catalyst ZnFe2O4.

18

Wpływ struktury leków sulfonamidowych na mechanizm inicjacji ich fotokatalitycznej degradacji

Baran Wojciech, Adamek Ewa, Cholewiński Mateusz, Krumpholz Laura, Kulej Barbara, Łazarczyk Antoni, Ledwoń Szymon

Proceedings of ECOpole

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2020

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Vol. 14, No. 1

69--87

PL

Sulfonamidy, pochodne sulfanilamidu, stanowią dużą grupę leków o właściwościach bakteriostatycznych. Część z nich jest powszechnie wykorzystywana w hodowli zwierząt w celach profilaktycznych i leczniczych. Następnie ich pozostałości trafiają do środowiska, gdzie stanowią uciążliwe i trwałe zanieczyszczenie. Leki te znacznie różnią się podatnością na fotokatalityczną degradację. Prowadzone badania pozwoliły na wyznaczenie związku pomiędzy strukturą sulfonamidów a drogą inicjacji ich rozkładu podczas naświetlania w obecności TiO2. Pozwoliły również na prognozowanie zastosowania procesu fotokatalitycznego do usuwania farmaceutyków z odpadów pohodowlanych.

EN

Sulfonamides, sulfanilamide derivatives, are a large group of drugs with bacteriostatic properties. Some of them are widely used in breeding for prophylactic and therapeutic purposes. Their residues get into the environment (soil, surface waters, and ground waters) where they are regarded as persistent organic pollutant. These drugs differ significantly in susceptibility to photocatalytic degradation. Sulfonamides differ significantly in susceptibility to the photocatalytic degradation. The study allowed to determine the relationship between the sulfonamides structure and the mechanism of initiation of their degradation during UV-A irradiation in the presence of TiO2 as a photocatalyst. Additionally, the results allowed us to develop a project involving the application of the photocatalytic process to the removal of pharmaceuticals from post-culture waste.

19

Aerobowa degradacja ampicyliny w glebie

Adamek Ewa, Baran Wojciech, Adamczyk Roman

Proceedings of ECOpole

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2020

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Vol. 14, No. 1

59--67

PL

Ampicylina jest antybiotykiem należącym do grupy b-laktamów. Jest ona powszechnie stosowana w weterynarii, a wraz z odchodami zwierząt hodowlanych jest wprowadzana do gleby. Może to mieć negatywne skutki dla bytujących tam mikroorganizmów i sprzyjać rozwojowi lekooporności. Celem pracy było wyznaczenie kinetyki rozkładu ampicyliny inicjowanej przez mikroorganizmy glebowe w warunkach aerobowych. Ponadto dokonano identyfikacji produktów tego procesu za pomocą techniki UPLC-QTOF oraz określono ich wypadkowy wpływ na mikroorganizmy pochodzące ze środowiska wodnego wykorzystywane w teście MARA®. Stwierdzono, że mikroorganizmy pochodzące z gleby powodują rozkład ampicyliny. Proces ten przebiega przede wszystkim poprzez eliminację podstawników, a następnie otwarcie pierścienia laktamowego. Efektem jest obniżenie wypadkowej toksyczności chronicznej roztworów zawierających ampicylinę względem mikroorganizmów testowych.

EN

Ampicillin is an antibiotic belonging to the beta-lactam group. It is widely used in veterinary medicine and therefore the residues are introduced into the soil with the livestock excreta. Such action could have a negative effect on soil microorganisms, including their biodiversity, and promote the development of drug resistance. The aim of our work was to determine the kinetics of ampicillin degradation initiated by soil microorganisms under aerobic conditions. The biodegradation products were identified using UPLC-QTOF. Additionally, the effects of these products on the microorganisms from the aquatic environment and the ones used in the MARA® bioassay were determined. It was found that the soil microorganisms caused the ampicillin degradation. The process proceeded mainly via elimination of one or more moieties from antibiotic molecule and opening of beta-lactam ring. In a result, a decrease in resultant chronic toxicity of ampicillin solutions to the test microorganisms was observed.

20

Acidified water glass in the selective flotation of scheelite from calcite, part II: species in solution and related mechanism of the depressant

Kupka Nathalie, Kaden Peter, Jantschke Anne, Schach Edgar, Rudolph Martin

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 5

797--817

EN

Sodium silicate is one of the main depressants against calcite and fluorite in the scheelite flotation industry. In the first part of this article, the authors acidified sodium silicate (AWG) with three acids (sulfuric, oxalic and hydrochloric) to improve its performance. Results showed that acidified water glass outperforms alkaline water glass in terms of selectivity: it increases mainly the grade by further depressing silicates and calcium-bearing minerals. In most cases, AWG requires lower dosages to do so. The effect of acidified water glass is evaluated through Mineral Liberation Analysis (MLA), froth analysis, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy in order to hypothesize its mechanism. MLA shows that AWG affects silicates and sulfides more intensely than semi-soluble salttype minerals. Froth observations indicate other species in solution associated to the acid having an impact on the flotation results. Raman spectroscopy and NMR measurements indicate that the solution undergoes deep depolymerization when water glass is acidified. Lower molecular weight silica species, specifically Si-O monomers such as SiO(OH)3- will be responsible for the depression of the gangue minerals and are the drivers of the selectivity of AWG, more than orthosilicic acid. Depolymerization is more or less effective depending on the mass ratio of the acid to water glass and depending on the acid.