Search results for: single metal atom catalysts

Authors: G. G. Kagramanov, E. N. Farnosova, Linn Maung Maung

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The technologies of ion exchange and nanofiltration can be used for treatment of wastewater containing copper and other heavy metal ions to decrease the environmental risks. Nanofiltration characteristics under water treatment of heavy metals have been studied. The influence of main technical process parameters - pressure, temperature, concentration and pH value of the initial solution on flux and rejection of nanofiltration membranes has been considered. And ion exchange capacities of resins in removal of heavy metal ions from wastewater have been determined.

Keywords: exchange capacity, heavy metals, ion exchange, membrane separation, nanofiltration

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Authors: R. Schurig, T. Désesquelles, A. Dumont, E. Lefranc, A. Lux

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A cost-efficient alternative is proposed to the use of a single drone carrying multiple cameras in order to take stereoscopic images and videos during its flight. Such drone has to be particularly large enough to take off with its equipment, and stable enough in order to make valid measurements. Corresponding performance for a single aircraft usually comes with a large cost. Proposed solution consists in using multiple smaller and cheaper aircrafts carrying one camera each instead of a single expensive one. To give a proof of concept, AR drones, quad-rotor UAVs from Parrot Inc., are experimentally used.

Keywords: drone squadron, flight control, rotorcraft, Unmanned Aerial Vehicle (UAV), AR drone, stereoscopic vision

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Authors: Hristina Šalipur, Jasmina Dostanić, Davor Lončarević, Matej Huš

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Photocatalytic water splitting/alcohol photoreforming has been used for the conversion of sunlight energy in the process of hydrogen production due to its sustainability, environmental safety, effectiveness and simplicity. Titanate nanotubes are frequently studied materials since they combine the properties of photo-active semiconductors with the properties of layered titanates, such as the ion-exchange ability. Platinum (Pt) doping into titanate structure has been considered an effective strategy in better separation efficiency of electron-hole pairs and lowering the overpotential for hydrogen production, which results in higher photocatalytic activity. In our work, Pt doped titanate catalysts were synthesized via simple alkaline hydrothermal treatment, incipient wetness impregnation method and temperature-programmed reduction. The structural, morphological and optical properties of the prepared catalysts were investigated using various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, and diffuse reflectance spectroscopy (DRS). The activities of the prepared Pt-doped titanate photocatalysts were tested for hydrogen production via photocatalytic water splitting/alcohol photoreforming process under simulated solar light irradiation. Characterization of synthesized Pt doped titanate catalysts showed crystalline anatase phase, preserved nanotubular structure and high specific surface area. The result showed enhancement of activity in photocatalytic water splitting/alcohol photoreforming in the following order 2-butanol>1-butanol>tert-butanol, with obtained maximal hydrogen production rate of 7.5, 5.3 and 2 mmol g-1 h-1, respectively. Different possible factors influencing the hole scavenging ability, such as hole scavenger redox potential and diffusivity, adsorption and desorption rate of the hole scavenger on the surface and stability of the alcohol radical species generated via hole scavenging, were investigated. The theoretical evaluation using density functional theory (DFT) further elucidated the reaction kinetics and detailed mechanism of photocatalytic water splitting/alcohol photoreforming.

Keywords: hydrogen production, platinum, semiconductor, water splitting, density functional theory

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Authors: Nagwa Mourad Abdelazeem, Marwa El-hussieny

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Multicomponent reactions (MCRs), one-pot reactions form products from more than two different starting compounds. (MCRs) are ideal reaction systems leading to high structural diversity and molecular complexity through a single transformation. (MCRs) have a lot of advantage such as higher yield, less waste generation, use of readily available starting materials and high atom. (MCRs) provide a rapid process for efficient synthesis of key structures in discovery of drug on the other hand silica sulfuric acid (SSA) has been used as an efficient heterogeneous catalyst for many organic transformations. (SSA) is low cost, ease of preparation, catalyst recycling, and ease of handling, so in this article we used 2-(thiophen-2-yl)-1H-indole, N-substituted anilines and aldehyde in the presence of silica sulfuric acid (SSA) as a catalyst in water as solvent at room temperature to prepare 3,3'-(phenylmethylene)bis(2-(thiophen-2-yl)-1H-indole) and N-methyl-4-(phenyl(2-(thiophen-2-yl)-1H-indol-3-yl)methyl)aniline derivatives Via one-pot reaction. Compound 2-(thiophen-2-yl)-1H-indole belongs to the ubiquitous class of indoles which enjoy broad synthetic, biological and industrial applications ]. Cancer is considered the first or second most common reason of death all through the world. So the synthesized compounds will be tested as anticancer. We expected the synthesized compounds will give good results comparison to the reference drug.

Keywords: aldehydes, aza-friedel-crafts reaction, indole, multicomponent reaction

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Authors: Mohamed Seghouani, Ahmed Tafraoui, Soltane Lebaili

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The purpose of this study widened knowledge on the use of the cutting tools out of metal carbide and to define it the influence of the elements of the mode of cut on the behavior of these tools during the machining of treated steel XC38 and untreated. This work aims at evolution determined in experiments of the wear of a cutting tool out of metal carbide with plate reported of P30 nuance for an operation of slide-lathing in turning on soaked and not hardened steel XC38 test-tubes. This research is based on the model of Taylor to determine the life span of the cutting tool according to the various parameters of cut, like the cutting speed Vc, the advance of cut a, the depth of cutting P. In order to express the operational limits of the tool for slide-lathing in a preventive way. The model makes it possible to determine the time of change of the tool and to regard it as a constraint for the respect of the roughness of the workpiece during a work of series in conventional machining.

Keywords: machining, wear, lifespan, model of Taylor, cutting tool, carburize metal

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Authors: Peikun Zhang, Chunhua Cui

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Photoelectrochemical (PEC) water splitting provides a promising pathway to convert solar energy into renewable fuels. However, the main and seemingly insurmountable obstacle is that the sluggish kinetics of oxygen evolution reaction (OER) severely jeopardizes the overall efficiency, thus exploring highly active, stable, and appreciable catalysts is urgently requested. Herein a competitive coordination strategy was demonstrated to form a reversible hybrid homo-heterogeneous catalyst for efficient OER in alkaline media. The dynamic process involves an in-situ anchoring of soluble nickel–bipyridine pre-catalyst to a conductive substrate under OER and a re-dissolution course under open circuit potential, induced by the competitive coordination between nickel–bipyridine and nickel-hydroxyls. This catalyst allows to elaborately self-modulate a charge-transfer layer thickness upon the catalytic on-off operation, which affords substantially increased active sites, yet remains light transparency, and sustains the stability of over 200 hours of continuous operation. The integration of this catalyst with exemplified state-of-the-art Ni-sputtered Si photoanode can facilitate a ~250 mV cathodic shift at a current density of 20 mA cm-2. This finding helps the understanding of catalyst from a “dynamic” perspective, which represents a viable alternative to address remaining hurdles toward solar-driven water oxidation.

Keywords: molecular catalyst, oxygen evolution reaction, solar energy, transition metal complex, water splitting

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Authors: Si-Geun Choi, Hoon-Jae Park, Jung-Woo Cho, Jin-Ho Lim, Jin-Young Park, Joo-Young Oh, Jae-Il Jeong Seock-Sam Kim, Young Tae Cho, Chan Gyu Kim, Jong-Hyoung Kim

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The tilting pad bearing is a kind of the fluid film bearing and it can contribute to the high speed and the high load performance compared to other bearings including the rolling element bearing. Furthermore, the tilting bearing has many advantages such as high stability at high-speed performance, long life, high damping, high impact resistance and low noise. Therefore, it mostly used in mid to large size turbomachines, despite the high price disadvantage. Recently, manufacture and process employing laser techniques advancing at a fast-growing rate in mechanical industry, the dissimilar metal weld process employing laser techniques is actively studied. Moreover, also, Industry fields try to apply for welding the white metal and the back metal using laser cladding method for high durability. Furthermore, it has followed that laser cladding method has a lot better bond strength, toughness, anti-abrasion and environment-friendly than centrifugal casting method through preceding research. Therefore, the laser cladding method has a lot better quality, cost reduction, eco-friendliness and permanence of technology than the centrifugal casting method or the gravity casting method. In this study, we compare the mechanical properties of different bearing materials by evaluating the behavior of laser cladding layer with various materials (i.e. SS400, SCM440, S20C) under the same parameters. Furthermore, we analyze the porosity of various tilting pad bearing materials which white metal treated on samples. SEM, EDS analysis and hardness tests of three materials are shown to understand the mechanical properties and tribological behavior. W/D ratio, surface roughness results with various materials are performed in this study.

Keywords: laser cladding, tilting pad bearing, white metal, mechanical properties

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Authors: Victor R. Thulari, John Akach, Haleden Chiririwa, Aoyi Ochieng

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Solar-light activated titanium dioxide photocatalysts were prepared by hydrolysis of titanium (IV) isopropoxide with thiourea, followed by calcinations at 450 °C. The experiments demonstrated that methyl orange in aqueous solutions were successfully degraded under solar light using doped TiO₂. The photocatalytic oxidation of a mono azo methyl-orange dye has been investigated in multi ion doped TiO₂ and solar light. Solutions were irradiated by solar-light until high removal was achieved. It was found that there was no degradation of methyl orange in the dark and in the absence of TiO₂. Varieties of laboratory prepared TiO₂ catalysts both un-doped and doped using titanium (IV) isopropoxide and thiourea as a dopant were tested in order to compare their photoreactivity. As a result, it was found that the efficiency of the process strongly depends on the working conditions. The highest degradation rate of methyl orange was obtained at optimum dosage using commercially produced TiO₂. Our work focused on laboratory synthesized catalyst and the maximum methyl orange removal was achieved at 81% with catalyst loading of 0.04 g/L, initial pH of 3 and methyl orange concentration of 0.005 g/L using multi-ion doped catalyst. The kinetics of photocatalytic methyl orange dye stuff degradation was found to follow a pseudo-first-order rate law. The presence of the multi-ion dopant (thiourea) enhanced the photoefficiency of the titanium dioxide catalyst.

Keywords: degradation, kinetics, methyl orange, photocatalysis

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Authors: Tia Kristian Tajnšek, Matjaž Mazaj, Nataša Zabukovec Logar

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Metal-organic frameworks (MOFs) with their specific properties and the possibility of tuning the structure represent excellent candidates for use in the biomedical field. Their advantage lies in large pore surfaces and volumes, as well as the possibility of using bio-friendly or bioactive constituents. So-called bioMOFs are representatives of MOFs, which are constructed from at least one biomolecule (metal, a small bioactive molecule in metal clusters and/or linker) and are intended for bio-application (usually in the field of medicine; most commonly drug delivery). When designing a bioMOF for biomedical applications, we should adhere to some guidelines for an improved toxicological profile of the material. Such as (i) choosing an endogenous/nontoxic metal, (ii) GRAS (generally recognized as safe) linker, and (iii) nontoxic solvents. Design and synthesis of bioNICS-1 (bioMOF of National Institute of Chemistry Slovenia – 1) consider all these guidelines. Zinc (Zn) was chosen as an endogenous metal with an agreeable recommended daily intake (RDI) and LD50 value, and ascorbic acid (Vitamin C) was chosen as a GRAS and active linker. With these building blocks, we have synthesized a bioNICS-1 material. The synthesis was done in ethanol using a solvothermal method. The synthesis protocol was further optimized in three separate ways. Optimization of (i) synthesis parameters to improve the yield of the synthesis, (ii) input reactant ratio and addition of specific modulators for production of larger crystals, and (iii) differing of the heating source (conventional, microwave and ultrasound) to produce nano-crystals. With optimization strategies, the synthesis yield was increased. Larger crystals were prepared for structural analysis with the use of a proper species and amount of modulator. Synthesis protocol was adjusted to different heating sources, resulting in the production of nano-crystals of bioNICS-1 material. BioNICS-1 was further activated in ethanol and structurally characterized, resolving the crystal structure of new material.

Keywords: ascorbic acid, bioMOF, MOF, optimization, synthesis, zinc ascorbate

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Authors: Cahit Demetgul, Sahin Bayraktar, Neslihan Beyazit

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Metalloenzymes are enzyme proteins containing metal ions, which are directly bound to the protein or to enzyme-bound nonprotein components. One of the major metalloenzymes that play a key role in oxidation reactions is catechol oxidase, which shows catecholase activity i.e. oxidation of a broad range of catechols to quinones through the four-electron reduction of molecular oxygen to water. Studies on the model compounds mimicking the catecholase activity are very useful and promising for the development of new, more efficient bioinspired catalysts, for in vitro oxidation reactions. In this study, a new tetradentate asymmetrical Schiff-base and its Cu(II) complex were synthesized by condensation of 4-nitro-1,2-phenylenediamine with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one and by using an appropriate Cu(II) salt, respectively. The prepared compounds were characterized by elemental analysis, FT-IR, NMR, UV-Vis and magnetic susceptibility. The catecholase-mimicking activity of the new Schiff Base Cu(II) complex was performed for the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in methanol at 25 °C, where the electronic spectra were recorded at different time intervals. The yield of the quinone (3,5-DTBQ) was determined from the measured absorbance at 400 nm of the resulting solution. The compatibility of catalytic reaction with Michaelis-Menten kinetics was also investigated. In conclusion, we have found that our new Schiff Base Cu(II) complex presents a significant capacity to catalyze the oxidation reaction of the catechol to o-quinone.

Keywords: catecholase activity, Michaelis-Menten kinetics, Schiff base, transition metals

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Authors: Merouani Djilali Redha, F. Abdelmalek, A. A. Addou

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Advanced oxidation processes (AOPs) utilizing Homogenous photocatalysis (Fenton and photo-Fenton reactions), and Heterogeneous photocatalyse (TiO2 and ZnO) were investigated for the degradation of commercial azo dye ‘Orange G’ wastewater. Fenton and photo-Fenton experimental conditions were: Hydrogen peroxide concentration (10-2 M), Ferrous ions concentration (5.10-4 M), pH (2.8 – 3), UV lamp power (6 watt). Adding more ferrous ions enhanced the oxidation rate for the H2O2/Fe2+ and UV/H2O2/Fe2+ processes. The optimum catalyst loading was found 2.0 g.L-1 in our case for both catalysts TiO2 and ZnO. A comparative study of the photocatalytic degradation showed that these two catalysts have a comparable reactivity; it follows a pseudo-first-order kinetics. The degradation trends followed the order: UV365/Fenton > UV365/TiO2 > Solar Fenton > Solar TiO2 > Fenton ~UV365/ZnO. Among AOPs, processes using Fenton type reagent are relatively cheap and easy to operate and maintain. Moreover, UV365/Fenton process has been shown as effective in the treatment of OG dye. Dye was degraded following second-order kinetics. The rate constants was 0,041 .10+6 L.M-1.min-1. The degradation was followed by spectrophotometric method, chemical oxygen demand (COD) measures and high performance liquid chromatography analyses (HPLC). Some aromatic and aliphatic degradation compounds were identified. Degradation of Orange G by UV Fenton mechanism was also proposed.

Keywords: AOPs, homogeneous catalysis, heterogeneous catalysis, acid orange 10, hydroxyl radical

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Authors: Mihir Kothari, Heena Khan, Vivek Rathod

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Assessment of binocular single vision field (BSVF) is traditionally done using a Goldmann perimeter. The measurement of BSVF is important for the management of incomitant strabismus, viz. orbital fractures, thyroid orbitopathy, oculomotor cranial nerve palsies, Duane syndrome etc. In this paper, we describe a new technique for measuring BSVF using a CROM device. Goldmann perimeter is very bulky and expensive (Euro 5000.00 or more) instrument which is 'almost' obsolete from the contemporary ophthalmology practice. Whereas, CROM can be easily made in the DIY (do it yourself) manner for the fraction of the price of the perimeter (only Euro 15.00). Moreover, CROM is useful for the accurate measurement of ocular torticollis vis. nystagmus, paralytic or incomitant squint etc, and it is highly portable.

Keywords: binocular single vision, perimetry, cervical rgen of motion, visual field, binocular single vision field

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Authors: Nirupama Dixit, Anyaa Mittal, Neeru Sood

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Alzheimer’s disease (AD) is a progressive form of dementia, contributing to up to 70% of cases, mostly observed in elderly but is not restricted to old age. The pathophysiology of the disease is characterized by specific pathological changes in brain. The changes (i.e. accumulation of metal ions in brain, formation of extracellular β-amyloid (Aβ) peptide aggregates and tangle of hyper phosphorylated Tau protein inside neurons) damage the neuronal connections irreversibly. The current issues in improvement of life quality of Alzheimer's patient lies in the fact that the diagnosis is made at a late stage of the disease and the medications do not treat the basic causes of Alzheimer's. The targeted delivery of drug through the blood brain barrier (BBB) poses several limitations via traditional approaches for treatment. To overcome these drug delivery limitation, nanoparticles provide a promising solution. This review focuses on current strategies for efficient targeted drug delivery using nanoparticles and improving the quality of therapy provided to the patient. Nanoparticles can be used to encapsulate drug (which is generally hydrophobic) to ensure its passage to brain; they can be conjugated to metal ion chelators to reduce the metal load in neural tissue thus lowering the harmful effects of oxidative damage; can be conjugated with drug and monoclonal antibodies against BBB endogenous receptors. Finally this review covers how the nanoparticles can play a role in diagnosing the disease.

Keywords: Alzheimer's disease, β-amyloid plaques, blood brain barrier, metal chelators, nanoparticles

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Authors: Quan Gu, Daniel Dimitrov

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BingleSeq was developed as a shiny-based, intuitive, and comprehensive application that enables the analysis of single-Cell RNA-Sequencing count data. This was achieved via incorporating three state-of-the-art software packages for each type of RNA sequencing analysis, alongside functional annotation analysis and a way to assess the overlap of differential expression method results. At its current state, the functionality implemented within BingleSeq is comparable to that of other applications, also developed with the purpose of lowering the entry requirements to RNA Sequencing analyses. BingleSeq is available on GitHub and will be submitted to R/Bioconductor.

Keywords: bioinformatics, functional annotation analysis, single-cell RNA-sequencing, transcriptomics

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Authors: Lana Whiskeyjack, Kyle Napier

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The Spirit of the language embodies the motivation for indigenous people to connect with the indigenous language of their lineage. While the concept of the spirit of the language is often woven into the discussion by indigenous language revitalizationists, particularly those who are indigenous, there are few tangible terms in academic research conceptually actualizing the term. Through collaborative work with indigenous language speakers, elders, and learners, this research sets out to identify the spirit of the language, the catalysts of disconnection from the spirit of the language, and the sources of reconnection to the spirit of the language. This work fundamentally addresses the terms of engagement around collaboration with indigenous communities, itself inviting a decolonial approach to community outreach and individual relationships. As indigenous researchers, this means beginning, maintain, and closing this work in the ceremony while being transparent with community members in this work and related publishing throughout the project’s duration. Decolonizing this approach also requires maintaining explicit ongoing consent by the elders, knowledge keepers, and community members when handling their ancestral and indigenous knowledge. The handling of this knowledge is regarded in this work as stewardship, both in the handling of digital materials and the handling of ancestral Indigenous knowledge. This work observes recorded conversations in both nêhiyawêwin and English, resulting from 10 semi-structured interviews with fluent nêhiyawêwin speakers as well as three structured dialogue circles with fluent and emerging speakers. The words were transcribed by a speaker fluent in both nêhiyawêwin and English. The results of those interviews were categorized thematically to conceptually actualize the spirit of the language, catalysts of disconnection to thespirit of the language, and community voices methods of reconnection to the spirit of the language. Results of these interviews vastly determine that the spirit of the language is drawn from the land. Although nêhiyawêwin is the focus of this work, Indigenous languages are by nature inherently related to the land. This is further reaffirmed by the Indigenous language learners and speakers who expressed having ancestries and lineages from multiple Indigenous communities. Several other key differences embody this spirit of the language, which include ceremony and spirituality, as well as the semantic worldviews tied to polysynthetic verb-oriented morphophonemics most often found in indigenous languages — and of focus, nêhiyawêwin. The catalysts of disconnection to the spirit of the language are those whose histories have severed connections between Indigenous Peoples and the spirit of their languages or those that have affected relationships with the land, ceremony, and ways of thinking. Results of this research and its literature review have determined the three most ubiquitously damaging interdependent factors, which are catalysts of disconnection from the spirit of the language as colonization, capitalism, and Christianity. As voiced by the Indigenous language learners, this work necessitates addressing means to reconnect to the spirit of the language. Interviewees mentioned that the process of reconnection involves a whole relationship with the land, the practice of reciprocal-relational methodologies for language learning, and indigenous-protected and -governed learning. This work concludes in support of those reconnection methodologies.

Keywords: indigenous language acquisition, indigenous language reclamation, indigenous language revitalization, nêhiyawêwin, spirit of the language

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Authors: Aresh Vikram Singh, Sarika Nagar

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The tamarind based resin containing hydroxypropane sulphonic acid groups has been synthesized and their adsorption behavior for heavy metal ions has been investigated using batch and column experiments. The hydroxypropane sulphonic acid group has been incorporated onto tamarind by a modified Porath's method of functionalisation of polysaccharides. The tamarind hydroxypropane sulphonic acid (THPSA) resin can selectively remove of heavy metal ions, which are contained in industrial wastewater. The THPSA resin was characterized by FTIR and thermogravimetric analysis. The effects of various adsorption conditions, such as pH, treatment time and adsorbent dose were also investigated. The optimum adsorption condition was found at pH 6, 120 minutes of equilibrium time and 0.1 gram of resin dose. The orders of distribution coefficient values were determined.

Keywords: distribution coefficient, industrial wastewater, polysaccharides, tamarind hydroxypropane sulphonic acid resin, thermogravimetric analysis, THPSA

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Authors: Daniel R. McDougall, Martin D. de Jonge, Gordon M. Miskelly, Duncan J. McGillivray, Andrew G. Jeffs

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The chelating agent ethylenediaminetetraacetic acid (EDTA) is commonly added as a cure-all to seawater in aquaculture hatcheries around the world to reduce heavy metal toxicity, significantly improve the survival of larval shellfish, and to therefore improve the overall production efficiency of the aquaculture industry. However, EDTA is not a biodegradable chemical and is considered to be a persistent organic pollutant, which will accumulate in the environment over time. This makes the use of EDTA unsustainable environmentally, and therefore alternatives should be considered. Ethylenediaminedisuccinic acid (EDDS) is a biodegradable alternative to EDTA with very similar metal chelation properties. This study investigates the effect of EDTA and EDDS at two different concentrations, on metal concentrations found within developing New Zealand green-lipped mussel (Perna canaliculus) larvae. P. canaliculus is New Zealand’s main shellfish aquaculture species, providing a major export for New Zealand’s economy, with excellent potential for increased production in the near future. It is well known that the early stages of bivalve development are the most vulnerable to metal toxicity and P. canaliculus is no exception. The commercially used concentration (12 µmol L⁻¹) of EDTA added to P. canaliculus larval rearing tanks often increases the yield of D-larvae by over 80%. This concentration of EDTA and EDDS will be tested in this study, along with a lower concentration (3 µmol L⁻¹). After 48 hours of larval development, the D-larvae will be analyzed for heavy metal content with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and heavy metal distribution with synchrotron X-ray Fluorescence Microscopy (XFM). In this study, we found that EDDS also improves the yield of P. canaliculus larvae and could be a viable alternative to EDTA in aquaculture. Furthermore, results suggest a higher concentration of chelating agent is more effective for improving the yield of developing P. canaliculus larvae. Metals with significant differences in concentration with the addition of EDTA were Cr, Cu, Zn, Cd and Pb (P < 0.05). We observed for the first time to the author’s best knowledge, metal distribution within 100 µm P. canaliculus D-larvae using synchrotron XFM and found changes in the distribution of metals with the addition of EDTA. XFM also has the potential to provide information about the chemical state of the metals within mussel larvae. This research provides greater insight into the reasons for the effectiveness of adding the chelating agent to aquaculture culture water, and a more environmentally conscious alternative to the currently used EDTA, which could be extremely valuable for the aquaculture industry.

Keywords: EDDS, EDTA, heavy metals, P. canaliculus, toxicity, water treatment

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Authors: Amar Al-Obaidi, Verena Kräusel, Dirk Landgrebe

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Induction assisted single point incremental forming (IASPIF) is a flexible method and can be simply utilized to form a high strength alloys. Due to the interaction between the mechanical and thermal properties during IASPIF an evaluation for the process is necessary to be performed analytically. Therefore, a numerical simulation was carried out in this paper. The numerical analysis was operated at both room and elevated temperatures then compared with experimental results. Fully coupled dynamic temperature displacement explicit analysis was used to simulated the hot single point incremental forming. The numerical analysis was indicating that during hot single point incremental forming were a combination between complicated compression, tension and shear stresses. As a result, the equivalent plastic strain was increased excessively by rising both the formed part depth and the heating temperature during forming. Whereas, the forming forces were decreased from 5 kN at room temperature to 0.95 kN at elevated temperature. The simulation shows that the maximum true strain was occurred in the stretching zone which was the same as in experiment.

Keywords: induction heating, single point incremental forming, FE modeling, advanced high strength steel

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Authors: Ahmet Yönetken

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Al metal matrix composites reinforced with AlN have been fabricated by Tube furnace sintering at various temperatures. A uniform nickel layer on Al(%1AlN)%19Ni, Al(%2AlN)%18Ni, Al(%3AlN)%17Ni, Al(%4AlN)%16Ni, Al(%5AlN)%15Ni powders were deposited prior to sintering using electroless plating technique, allowing closer surface contact than can be achieved using conventional methods such as mechanical alloying. A composite consisting of quaternary additions, a ceramic phase, AlN, within a matrix of Al, AlN, Ni has been prepared at the temperature range between 550°C and 650°C under Ar shroud. X-Ray diffraction, SEM (Scanning Electron Microscope) density, and hardness measurements were employed to characterize the properties of the specimens. Experimental results carried out for 650°C suggest that the best properties as comprehension strength σmax and hardness 681.51(HV) were obtained at 650°C, and the tube furnace sintering of electroless Al plated (%5AlN)%15Ni powders is a promising technique to produce ceramic reinforced Al (%5AlN)%15Ni composites.

Keywords: electroless nickel plating, ceramic-metal composites, powder metallurgy, sintering

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Authors: Qaiser Akram, Ahsan Naeem, Hafiz Muhammad Rizwan, Waqas Ahmad, Rubeena Yasmeen

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Aspergillus has good secretory potential for phytases. Morphologically and microscopically identified Aspergillus terreus (A. terreus) (n=20) were screened for phytase production and non-toxicity. Phytases produced by non-toxigenic A. terreus under optimum conditions were quantified. Phytases of highest producer A. terreus were evaluated for stability after exposure to temperature (35, 55, 75 and 95ºC) and pH (2, 4, 6 and 8). Effect of metal ions (Fe⁺³, Ba⁺², Ca⁺², Cu⁺², Mg⁺², Mn⁺², K⁺¹ and Na⁺¹) was assessed on phytase activity. Log reduction in phytase activity was calculated. The highest activity units of phytase produced by A. terreus were 271.49 ± 8.14 phytase unit / mL (FTU/ mL). The lowest reduction in phytase activity was 50.20 ± 7.36 (18.5%) and 68.22 ± 10.3 FTU/mL (25.13%) at 35ºC and pH 6, respectively for 15 minutes. The highest reduction 259 ± 0.84 (95.5%) and 211.99 ± 4.39 FTU/mL (78.1%) was recorded at 95ºC for 60 minutes and pH 2.0 for 45 minutes exposure, respectively. All metal ions negatively affected phytase activity. Phytase activity was inhibited minimum (45.32 ± 28.54 FTU/mL, 16.69%) by K⁺¹(1 mM) and maximum (231.48 ± 3.68 FTU/mL, 80.8%) by Cu⁺² (10 mM). It was concluded that A. terreus phytase stability and activity was dependent on physio-chemical factors.

Keywords: stability, phytase, aspergillus terreus, physio-chemical factors and metal ions

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Authors: Glynn K. Pindihama, Rabelani Mudzielwana, Ndamulelo Lilimu

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Wastewater treatment effluents, particularly sludges, are known to be potential sources of heavy metal contamination in the environment, depending on how the sludge is managed. Maintenance of wastewater treatment infrastructure in developing countries such as South Africa has become an issue of grave concern, with many wastewater treatment facilities in dilapidating states. Among the problems is the vandalism of the periphery fence to many wastewater treatment facilities, resulting in livestock, such as cows from neighboring villages, grazing within the facilities. This raises human health risks since dried sludge from the treatment plants is usually spread on the grass around the plant, resulting in heavy metal contamination. Animal products such as meat and milk from these cows thus become an indirect route to heavy metals to humans. This study assessed heavy metals in sludges from 3 wastewater treatment plants in Limpopo Province of South Africa. In addition, cow dung and sludge liquors were collected from these plants and evaluated for their heavy metal content. The sludge and cow dung were microwave-digested using the aqua-regia method, and all samples were analyzed for heavy metals using ICP-OES. The loadings of heavy metals in the sludge were in the order Cu>Zn>Ni>Cr>Cd>As>Hg. In cow dung, the heavy metals were in the order Fe>Cu>Mn>Zn>Cr>Pb>Co>Cd. The levels of Zn and Cu in the sludge liquors where the animals were observed drinking were, in some cases, above the permissible limit for livestock consumption. Principal component and correlation analysis are yet to be done to determine if there is a correlation between the heavy metals in the cow dung and sludge and sludge liquors.

Keywords: cow dung, heavy metals, sludge, wastewater treatment plants, sludge.

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Authors: K. Subbaiah, C. V. Jeyakumar, S. R. Koteswara Rao

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Cast Aluminum-Magnesium-Scandium alloy was Gas Tungsten Arc (GTA) welded, and the microstructure and mechanical properties of the joint and its component parts were examined and analyzed. The global joint fractured in the base metal, and thus possessed slightly greater tensile strength than the base metal. These results clearly show that Gas Tungsten Arc welding is an optimum / suitable welding process for cast Aluminum-Magnesium-Scandium alloys.

Keywords: cast Al-Mg-Sc alloy, GTAW, microstructure, mechanical properties

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Authors: Przewodowski Włodzimierz, Przewodowska Agnieszka, Sekrecka Danuta, Michałowska Dorota

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Colloidal metal nanoparticles are widely applied in various areas and have great potential in different biotechnological applications. Their particular properties associated with both the antiseptic, antioxidant and anti aging properties as well as ability to penetrate most of the biological barriers, synergy in the absorption of nutrients and nontoxic to plants. The properties make them potentially useful in the fast and safe production of healthy, certified starting material in the production of plants exposed to many pathogenic microorganisms causing serious diseases, significantly affecting yield and causing the economic losses. In this case it is crucial to provide appropriate conditions for the production, storage and distribution of the plant material. Therefore, the aim of the proposed research was to develop and identify the influence of four colloidal metal nanoparticles on growth and proliferation of in vitro cultures of potato (Solanum tuberosum) - one of the most economically important strategic crops in the world. The research on different varieties of potato was performed by placing the explants of the in vitro cultures on sterile Murashige and Skoog (MS) type medium. The influence of the nanocolloids was evaluated using the MS medium impregnated with the examinated nanoparticles. The vigour of growth and the rate of proliferation was examinated for 6-8 weeks with both night/day-length and temperature over the ranges 8/16 h and 20–22 °C respectively. The results of our preliminary work confirmed high usefulness of the nanocolloids in the safe production of the examinated in vitro cultures.

Keywords: colloidal metal nanoparticles, in vitro cultures, potato, propagation

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Authors: Chandrasekaran, Ravisankar N. Harikrishnan, Rajalakshmi, K. K. Satapathy M. V. R. Prasad, K. V. Kanagasabapathy

Abstract:

Heavy metals were considered as highly toxic environmental pollutants to soil ecosystem and human health. In present study the 12 heavy metals (Mg, Al, K, Ca, Ti, Fe, V, Cr, Mn, Co,Ni and Zn.) are determined in soils of Yelagiri hills, Tamilnadu by energy dispersive X-ray fluorescence technique. Metal concentrations were used to quantify pollution contamination factors such as enrichment factor (EF), geo-accumulation index (Igeo) and contamination factor (CF) are calculated and reported.

Keywords: soil, heavy metals, EDXRF, pollution contamination factors

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Authors: Farida Kaouah, Wassila Hachi, Lamia Brahmi, Chahida Ousselah, Salim Boumaza, Mohamed Trari

Abstract:

The feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water treatment. In this study, photocatalytic degradation of a widely used textile dye, Acid Blue 25 (AB25), with noble metal loaded ZnO photocatalyst (Ag/ZnO), was investigated in aqueous suspension under solar light. The results showed that the deposition of Ag as a noble metal onto the ZnO surface, improved the photodegradation of AB25. . The effect of different parameters such as catalyst dose, initial dye concentration, and contact time was optimized and the optimal degradation of AB25 (97%) was achieved for initial AB25 concentration of 24 mg L−1 an catalyst dose of 1 g L−1 at natural pH (5.42) after 180 min. The kinetic studies were achieved and revealed that the photocatalytic degradation process obeyed to Langmuir–Hinshelwood model and followed a pseudo-first order rate expression. This work envisages the great potential that sunlight photocatalysis has in the degradation of dyes from wastewater

Keywords: acid dye, photocatalytic degradation, sunlight, zinc oxide, noble metal, Langmuir–Hinshelwood model

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Authors: Tsung-Lin Hsieh, Jiun-Jen Chen, Yuhao Kang

Abstract:

Metal-organic frameworks (MOFs) have drawn scientists’ attention for decades due to its high specific surface area, tunable pore size, and relatively low temperature for regeneration. Bearing with those mentioned properties, MOFs has been widely used in various applications, such as adsorption/separation and catalysis. However, the current challenge for practical use of MOFs is to effectively shape these crystalline powder material into controllable forms such as pellets, granules, and monoliths with sufficient mechanical and chemical stability, while maintaining the excellent properties of MOFs powders. Herein, we have successfully synthesized an Al-based MOF powder which exhibits a high water capacity at relatively low humidity conditions and relatively low temperature for regeneration. Then the synthesized Al-MOF was shaped into granules with particle size of 2-4 mm by (1) tumbling granulation, (2) High shear mixing granulation, and (3) Extrusion techniques. Finally, the water vapor adsorption rate and crush strength of Al-MOF granules by different shaping techniques were measured and compared.

Keywords: granulation, granules, metal-organic frameworks, water vapor adsorption

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Authors: Ruqia Nazir, Robin Perutz

Abstract:

Collision-induced dissociation (CID) can be used to study the intrinsic properties of ions in the gas phase.1 Decay pathways of transition metal difluoride complexes of titanium, zirconium, hafnium, and ruthenium were studied by CID in an ESI-Ion trap mass spectrometer. Furthermore, the decay pathways of multiply charged anions (MCAs) of titanium and zirconium were also studied. The CID results are illustrated by the behaviour of (Cp*)₂TiF₂, which initially forms the ions [M-F-]⁺, [M+Na]⁺, and [M+K]⁺. The [(Cp*₂)TiF⁺ ion decays on resonant excitation to lose HF forming [Cp*(C₅Me₄CH₂)Ti]⁺ (Figure). The other major ion, [(Cp*)₂TiF₂+Na]⁺, decays on resonant excitation with production of [(Cp*)₂TiF₂]⁺ and [C₅Me₄CH₂]⁺. We also report the behaviour of Cp₂MF₂ (M = Zr, Hf) and Ru(PMe₃)₄F₂. The decay pathway of the multiply charged anions (MCAs), notably TiF₆²⁻ and ZrF₆²⁻ was concluded to be ionic fragmentation with loss of F⁻ rather than electron detachment.

Keywords: collision induced dissociation, transition metal difluoride comolexes, multiply charged anions, mass spectrometry

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Authors: S. Zhuiykov, Zh. Hai, H. Xu, C. Xue

Abstract:

Unique and distinctive properties could be obtained on such two-dimensional (2D) semiconductor as tungsten trioxide (WO₃) when the reduction from multi-layer to one fundamental layer thickness takes place. This transition without damaging single-layer on a large spatial resolution remained elusive until the atomic layer deposition (ALD) technique was utilized. Here we report the ALD-enabled atomic-layer-precision development of a single layer WO₃ with thickness of 0.77±0.07 nm on a large spatial resolution by using (^tBuN)₂W(NMe₂)₂ as tungsten precursor and H₂O as oxygen precursor, without affecting the underlying SiO₂/Si substrate. Versatility of ALD is in tuning recipe in order to achieve the complete WO₃ with desired number of WO₃ layers including monolayer. Governed by self-limiting surface reactions, the ALD-enabled approach is versatile, scalable and applicable for a broader range of 2D semiconductors and various device applications.

Keywords: Atomic Layer Deposition (ALD), tungsten oxide, WO₃, two-dimensional semiconductors, single fundamental layer

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Authors: Karim Hrratha, Khaled Essalahb, Christophe Morellc, Henry Chermettec, Salima Boughdiria

Abstract:

Among the carbon-carbon bond formation types, allylation of active methylene compounds with cyclic Baylis-Hillman (BH) alcohols is a reliable and widely used method. This reaction is a very attractive tool in organic synthesis of biological and biodiesel compounds. Thus, in view of an insistent and peremptory request for an efficient and straightly method for synthesizing the desired product, a thorough analysis of various aspects of the reaction processes is an important task. The product afforded by the reaction of active methylene with BH alcohols depends largely on the experimental conditions, notably on the catalyst properties. All experiments reported that catalysis is needed for this reaction type because of the poor ability of alcohol hydroxyl group to be as a suitable leaving group. Within the catalysts, several transition- metal based have been used such as palladium in the presence of acid or base and have been considered as reliable methods. Furthemore, acid catalysts such as BF3.OEt2, BiX3 (X= Cl, Br, I, (OTf)3), InCl3, Yb(OTf)3, FeCl3, p-TsOH and H-montmorillonite have been employed to activate the C-C bond formation through the alkylation of active methylene compounds. Interestingly a report of a smoothly process for the ability of 4-imethyaminopyridine(DMAP) to catalyze the allylation reaction of active methylene compounds with cyclic Baylis-Hillman (BH) alcohol appeared recently. However, the reaction mechanism remains ambiguous, since the C- allylation process leads to an unexpected product (noted P1), corresponding to a direct allylation instead of conjugate allylation, which involves the most electrophilic center according to the electron withdrawing group CO effect. The main objective of the present theoretical study is to better understand the role of the DMAP catalytic activity as well as the process leading to the end- product (P1) for the catalytic reaction of a cyclic BH alcohol with active methylene compounds. For that purpose, we have carried out computations of a set of active methylene compounds varying by R1 and R2 toward the same alcohol, and we have attempted to rationalize the mechanisms thanks to the acid–base approach, and conceptual DFT tools such as chemical potential, hardness, Fukui functions, electrophilicity index and dual descriptor, as these approaches have shown a good prediction of reactions products.The present work is then organized as follows: In a first part some computational details will be given, introducing the reactivity indexes used in the present work, then Section 3 is dedicated to the discussion of the prediction of the selectivity and regioselectivity. The paper ends with some concluding remarks. In this work, we have shown, through DFT method at the B3LYP/6-311++G(d,p) level of theory that: The allylation of active methylene compounds with cyclic BH alcohol is governed by orbital control character. Hence the end- product denoted P1 is generated by direct allylation.

Keywords: DFT calculation, gas phase pKa, theoretical mechanism, orbital control, charge control, Fukui function, transition state

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Authors: German Osma, Gabriel Ordonez

Abstract:

The production of metal-rubber spares for vehicles is a sequential process that consists in the transformation of raw material through cutting activities and chemical and thermal treatments, which demand electricity and fossil fuels. The energy efficiency analysis for these cases is mostly focused on studying of each machine or production step, but is not common to study of the quality of the production process achieves from aggregated value viewpoint, which can be used as a quality measurement for determining of impact on the environment. In this paper, the theory of exergetic cost is used for determining of aggregated exergy to three metal-rubber spares, from an exergy analysis and thermoeconomic analysis. The manufacturing processing of these spares is based into batch production technique, and therefore is proposed the use of this theory for discontinuous flows from of single models of workstations; subsequently, the complete exergy model of each product is built using flowcharts. These models are a representation of exergy flows between components into the machines according to electrical, mechanical and/or thermal expressions; they determine the demanded exergy to produce the effective transformation in raw materials (aggregated exergy value), the exergy losses caused by equipment and irreversibilities. The energy resources of manufacturing process are electricity and natural gas. The workstations considered are lathes, punching presses, cutters, zinc machine, chemical treatment tanks, hydraulic vulcanizing presses and rubber mixer. The thermoeconomic analysis was done by workstation and by spare; first of them describes the operation of the components of each machine and where the exergy losses are; while the second of them estimates the exergy-aggregated value for finished product and wasted feedstock. Results indicate that exergy efficiency of a mechanical workstation is between 10% and 60% while this value in the thermal workstations is less than 5%; also that each effective exergy-aggregated value is one-thirtieth of total exergy required for operation of manufacturing process, which amounts approximately to 2 MJ. These troubles are caused mainly by technical limitations of machines, oversizing of metal feedstock that demands more mechanical transformation work, and low thermal insulation of chemical treatment tanks and hydraulic vulcanizing presses. From established information, in this case, it is possible to appreciate the usefulness of theory of exergetic cost for analyzing of aggregated value in manufacturing processes.

Keywords: exergy-aggregated value, exergy efficiency, thermoeconomics, exergy modeling

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