Search results for: hydrogen peroxide vapor

Authors: Amal M. Nassar, Nehal S. Ahmed, Rasha S. Kamal

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Some lube oil additives improve the base oil performance such as viscosity index improvers and pour point depressants which are the most important type of additives. In the present work, some homopolymeric additives were prepared by esterification of acrylic acid with different alcohols (1-dodecyl, 1-hexadecyl, and 1-octadecyl )and then homopolymerization of the prepared esters with different ratio of benzoyl peroxide catalyst (0.25%& 0.5 % and 1%). Structure of the prepared esters was confirmed by Infra-Red Spectroscopy. The molecular weights of the prepared homopolymers were determined by using Gel Permeation Chromatograph. The efficiency of the prepared homopolymers as viscosity index improvers and pour point depressants for lube oil was the investigation. It was found that all the prepared homopolymers are effective as viscosity index improvers and pour point depressants.

Keywords: lube oil additives, homopolymerization, viscosity index improver, pour point depressant

Procedia PDF Downloads 222

Authors: Natalie Pomerantz, Nicholas Dugan, Molly Richards, Walter Zukas

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The primary research question to be answered for Chemical/Biological (CB) protective clothing, is how to protect wearers from a range of chemical and biological threats in liquid, vapor, and aerosol form, while reducing the thermal burden. Currently, CB protective garments are hot, heavy, and wearers are limited by short work times in order to prevent heat injury. This study demonstrates how to incorporate different levels of protection on a material level and modify fabric composites such that the thermal burden is reduced to such an extent it approaches that of a standard duty uniform with no CB protection. CB protective materials are usually comprised of several fabric layers: a cover fabric with a liquid repellent coating, a protective layer which is comprised of a carbon-based sorptive material or semi-permeable membrane, and a comfort next-to-skin liner. In order to reduce thermal burden, all of these layers were laminated together to form one fabric composite which had no insulative air gap in between layers. However, the elimination of the air gap also reduced the CB protection of the fabric composite. In order to increase protection in the laminated composite, different nonwoven aerosol protective liners were added, and a super repellent coating was applied to the cover fabric, prior to lamination. Different adhesive patterns were investigated to determine the durability of the laminate with the super repellent coating, and the effect on air permeation. After evaluating the thermal properties, textile properties and protective properties of the iterations of these fabric composites, it was found that the thermal burden of these materials was greatly reduced by decreasing the thermal resistance with the elimination of the air gap between layers. While the level of protection was reduced in laminate composites, the addition of a super repellent coating increased protection towards low volatility agents without impacting thermal burden. Similarly, the addition of aerosol protective liner increased protection without reducing water vapor transport, depending on the nonwoven used, however, the air permeability was significantly decreased. The balance of all these properties and exploration of the trade space between thermal burden and protection will be discussed.

Keywords: aerosol protection, CBRNe protection, lamination, nonwovens, repellent coatings, thermal burden

Procedia PDF Downloads 355

Authors: Akan C. Offong, E. J. Anthony, Vasilije Manovic

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A modified steady-state numerical model is developed for the electrochemical reduction of CO₂ to formic acid. The numerical model achieves a CD (current density) (~60 mA/cm²), FE-faradaic efficiency (~98%) and conversion (~80%) for CO₂ electro-reduction to formic acid in a microfluidic cell. The model integrates charge and species transport, mass conservation, and momentum with electrochemistry. Specifically, the influences of Bi-Sn based nanoparticle catalyst (on the cathode surface) at different mole fractions and 1-ethyl-3-methyl imidazolium tetra-fluoroborate ([EMIM][BF₄]) electrolyte, on CD, FE and CO₂ conversion to formic acid is studied. The reaction is carried out at a constant concentration of electrolyte (85% v/v., [EMIM][BF₄]). Based on the mass transfer characteristics analysis (concentration contours), mole ratio 0.5:0.5 Bi-Sn catalyst displays the highest CO₂ mole consumption in the cathode gas channel. After validating with experimental data (polarisation curves) from literature, extensive simulations reveal performance measure: CD, FE and CO₂ conversion. Increasing the negative cathode potential increases the current densities for both formic acid and H₂ formations. However, H₂ formations are minimal as a result of insufficient hydrogen ions in the ionic liquid electrolyte. Moreover, the limited hydrogen ions have a negative effect on formic acid CD. As CO₂ flow rate increases, CD, FE and CO₂ conversion increases.

Keywords: carbon dioxide, electro-chemical reduction, ionic liquids, microfluidics, modelling

Procedia PDF Downloads 139

Authors: Jerzy Ejsmont, Beata Świeczko-Żurek, Grzegorz Ronowski

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Gas cylinders in general and particularly cylinders containing acetylene constitute a great potential danger for fire and rescue services involved in salvage operations. Experiments show that gas cylinders with acetylene, oxygen, hydrogen, CNG, LPG or CO2 may blow after short exposition to heat with very destructive effect as fragments of blown cylinder may fly even several hundred meters. In the case of acetylene, the explosion may occur also several hours after the cylinder is cooled down. One of the possible neutralization procedures that in many cases may be used to prevent explosions is shooting dangerous cylinders by rifle bullets. This technique is used to neutralize acetylene cylinders in a few European countries with great success. In Poland research project 'BLOW' was launched in 2014 with the aim to investigate phenomena related to fire influence on industrial and home used cylinders and to evaluate usefulness of the shooting technique. All together over 100 gas cylinders with different gases were experimentally tested at the military blasting grounds and in shelters. During the experiments cylinder temperature and pressure were recorded. In the case of acetylene that is subjected to thermal decomposition also concentration of hydrogen was monitored. Some of the cylinders were allowed to blow and others were shot by snipers. It was observed that shooting hot cylinders has never created more dangerous situations than letting the cylinders to explode spontaneously. In a great majority of cases cylinders that were punctured by bullets released gas in a more or less violent but relatively safe way. The paper presents detailed information about experiments and presents particularities of behavior of cylinders containing different gases. Extensive research was also done in order to select bullets that may be safely and efficiently used to puncture different cylinders. The paper shows also results of those experiments as well as gives practical information related to techniques that should be used during shooting.

Keywords: fire, gas cylinders, neutralization, shooting

Procedia PDF Downloads 256

Authors: S. Zidani, A. Benakmoum, A. Mansouri, A. Ammouche

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In this research paper, we studied the oxidative stability of table margarine and soya/sunflower oils rich in lycopene with tomato peel powder (TPP). For this 1%, 2%, and 3% (w/w) of TPP was added to oil used in margarine manufacture. Chromatic characteristics of margarine and soya/sunflower oil have been studied using 'Tristimulus Colorimetry' method. The main point of the research was to determine the antioxidant activity and the oxidative resistance of soya/sunflower and margarine with TPP (peroxide index, TBA index, and rancimat test). The sensory and textural properties, overall acceptability of margarine and oil were good, indicating that TPP could be added to oil to produce a margarine enriched in lycopene with excellent stability oxidative.

Keywords: tomato peel powder, lycopene, table margarine, soya/sunflower oils, antioxidant activity, stability oxidative

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Authors: Igor B. Sivaev

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Design of molecular machines is an extraordinary growing and very important area of research that it was recognized by awarding Sauvage, Stoddart and Feringa the Nobel Prize in Chemistry in 2016 'for the design and synthesis of molecular machines'. Based on the type of motion being performed, molecular machines can be divided into two main types: molecular motors and molecular switches. Molecular switches are molecules or supramolecular complexes having bistability, i.e., the ability to exist in two or more stable forms, among which may be reversible transitions under external influence (heating, lighting, changing the medium acidity, the action of chemicals, exposure to magnetic or electric field). Molecular switches are the main structural element of any molecular electronics devices. Therefore, the design and the study of molecules and supramolecular systems capable of performing mechanical movement is an important and urgent problem of modern chemistry. There is growing interest in molecular switches and other devices of molecular electronics based on transition metal complexes; therefore choice of suitable stable organometallic unit is of great importance. An example of such unit is bis(dicarbollide) complexes of transition metals [3,3’-M(1,2-C₂B₉H₁₁)₂]ⁿ⁻. The control on the ligand rotation in such complexes can be reached by introducing substituents which could provide stabilization of certain rotamers due to specific interactions between the ligands, on the one hand, and which can participate as Lewis bases in complex formation with external metals resulting in a change in the rotation angle of the ligands, on the other hand. A series of isomeric methyl sulfide derivatives of cobalt bis(dicarbollide) complexes containing methyl sulfide substituents at boron atoms in different positions of the pentagonal face of the dicarbollide ligands [8,8’-(MeS)₂-3,3’-Co(1,2-C₂B₉H₁₀)₂]⁻, rac-[4,4’-(MeS)₂-3,3’-Co(1,2-C₂B₉H₁₀)₂]⁻ and meso-[4,7’-(MeS)₂-3,3’-Co(1,2-C₂B₉H₁₀)₂]⁻ were synthesized by the reaction of CoCl₂ with the corresponding methyl sulfide carborane derivatives [10-MeS-7,8-C₂B₉H₁₁)₂]⁻ and [10-MeS-7,8-C₂B₉H₁₁)₂]⁻. In the case of asymmetrically substituted cobalt bis(dicarbollide) complexes the corresponding rac- and meso-isomers were successfully separated by column chromatography as the tetrabutylammonium salts. The compounds obtained were studied by the methods of ¹H, ¹³C, and ¹¹B NMR spectroscopy, single crystal X-ray diffraction, cyclic voltammetry, controlled potential coulometry and quantum chemical calculations. It was found that in the solid state, the transoid- and gauche-conformations of the 8,8’- and 4,4’-isomers are stabilized by four intramolecular CH···S(Me)B hydrogen bonds each one (2.683-2.712 Å and 2.709-2.752 Å, respectively), whereas gauche-conformation of the 4,7’-isomer is stabilized by two intramolecular CH···S hydrogen bonds (2.699-2.711 Å). The existence of the intramolecular CH·S(Me)B hydrogen bonding in solutions was supported by the 1H NMR spectroscopy. These data are in a good agreement with results of the quantum chemical calculations. The corresponding iron and nickel complexes were synthesized as well. The reaction of the methyl sulfide derivatives of cobalt bis(dicarbollide) with various labile transition metal complexes results in rupture of intramolecular hydrogen bonds and complexation of the methyl sulfide groups with external metal. This results in stabilization of other rotational conformation of cobalt bis(dicarbollide) and can be used in design of molecular switches. This work was supported by the Russian Science Foundation (16-13-10331).

Keywords: molecular switches, NMR spectroscopy, single crystal X-ray diffraction, transition metal bis(dicarbollide) complexes, quantum chemical calculations

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Authors: Nasim Abuali Galehdari, Venkat Mani, Ajit D. Kelkar

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Space Radiation has become one of the major factors in successful long duration space exploration. Exposure to space radiation not only can affect the health of astronauts but also can disrupt or damage materials and electronics. Hazards to materials include degradation of properties, such as, modulus, strength, or glass transition temperature. Electronics may experience single event effects, gate rupture, burnout of field effect transistors and noise. Presently aluminum is the major component in most of the space structures due to its lightweight and good structural properties. However, aluminum is ineffective at blocking space radiation. Therefore, most of the past research involved studying at polymers which contain large amounts of hydrogen. Again, these materials are not structural materials and would require large amounts of material to achieve the structural properties needed. One of the materials to alleviate this problem is polymeric composite materials, which has good structural properties and use polymers that contained large amounts of hydrogen. This paper presents steps involved in fabrication of multi-functional hybrid sandwich panels that can provide beneficial radiation shielding as well as structural strength. Multifunctional hybrid sandwich panels were manufactured using vacuum assisted resin transfer molding process and were subjected to radiation treatment. Study indicates that various nanoparticles including Boron Nano powder, Boron Carbide and Gadolinium nanoparticles can be successfully used to block the space radiation without sacrificing the structural integrity.

Keywords: multi-functional, polymer composites, radiation shielding, sandwich composites

Procedia PDF Downloads 275

Authors: Tsegay Teklebrhan Gebremariam, Zhiliang, Arjan Jonker

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The study investigated that using corn gluten (CG) instead of cornmeal (CM) increased dietary sulfur shifted H₂ metabolism from methanogenesis to alternative sink and modulated microbiome in the rumen as well as hindgut segments of goats. Ruminal fermentation, CH₄ emissions and microbial abundance in goats (n = 24). The experiment was performed using a randomized block design with two dietary treatments (CM and CG with 400 g/kg DM each). Goats in CG increased sulfur, NDF and CP intake and decreased starch intake as compared with those in CM. Goats that received CG diet had decreased dissolved hydrogen (dH₂) (P = 0.01) and dissolved methane yield and emission (dCH₄) (P = 0.001), while increased dH₂S both in the rumen and hindgut segments than those fed CM. Goats fed CG had higher (p < 0.01) gene copies of microbiota and cellulolytic bacteria, whereas starch utilizing bacterial species were less in the rumen and hindgut than those fed CM. Higher (P < 0.05) methanogenic diversity and abundances of Methanimicrococcus and Methanomicrobium were observed in goats that consumed CG, whilst containing lower Methanobrevibacter populations than those receiving CM. The study suggested that goats fed corn gluten improved the gene copies of microbiota and fibrolytic bacterial species while reducing starch utilizing species in the rumen and hindgut segments as compared with that fed cornmeal. Goats consuming corn gluten had a more enriched methanogenic diversity and reduced Methanobrevibacter, a contributor to CH₄ emissions, as compared with goats fed CM. Corn gluten could be used as an alternative feed to decrease the enteric CH₄ emission in ruminant production.

Keywords: dissolved gasses, methanogenesis, microbial community, metagenomics

Procedia PDF Downloads 151

Authors: Wilman Septina, Rajiv R. Prabhakar, Thomas Moehl, David Tilley

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Cupric oxide (CuO) is a promising absorber material for the fabrication of scalable, low cost solar energy conversion devices, due to the high abundance and low toxicity of copper. It is a p-type semiconductor with a band gap of around 1.5 eV, absorbing a significant portion of the solar spectrum. One of the main challenges in using CuO as solar absorber in an aqueous system is its tendency towards photocorrosion, generating Cu2O and metallic Cu. Although there have been several reports of CuO as a photocathode for hydrogen production, it is unclear how much of the observed current actually corresponds to H2 evolution, as the inevitability of photocorrosion is usually not addressed. In this research, we investigated the effect of the deposition of overlayers onto CuO thin films for the purpose of enhancing its photostability as well as performance for water splitting applications. CuO thin film was fabricated by galvanic electrodeposition of metallic copper onto gold-coated FTO substrates, followed by annealing in air at 600 °C. Photoelectrochemical measurement of the bare CuO film using 1 M phosphate buffer (pH 6.9) under simulated AM 1.5 sunlight showed a current density of ca. 1.5 mA cm-2 (at 0.4 VRHE), which photocorroded to Cu metal upon prolonged illumination. This photocorrosion could be suppressed by deposition of 50 nm-thick TiO2, deposited by atomic layer deposition. In addition, we found that insertion of an n-type CdS layer, deposited by chemical bath deposition, between the CuO and TiO2 layers was able to enhance significantly the photocurrent compared to without the CdS layer. A photocurrent of over 2 mA cm-2 (at 0 VRHE) was observed using the photocathode stack FTO/Au/CuO/CdS/TiO2/Pt. Structural, electrochemical, and photostability characterizations of the photocathode as well as results on various overlayers will be presented.

Keywords: CuO, hydrogen, photoelectrochemical, photostability, water splitting

Procedia PDF Downloads 212

Authors: Dhiflaoui Hafedh, Khlifi Kaouther, Ben Cheikh Larbi Ahmed

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Monolayer and multilayer coatings of CrN and AlCrN deposited on 100Cr6 (AISI 52100) substrate by PVD magnetron sputtering system. The micro structures of the coatings were characterized using atomic force microscopy (AFM). The AFM analysis revealed the presence of domes and craters which are uniformly distributed over all surfaces of the various layers. Nano indentation measurement of CrN coating showed maximum hardness (H) and modulus (E) of 14 GPa and 240 GPa, respectively. The measured H and E values of AlCrN coatings were found to be 30 GPa and 382 GPa, respectively. The improved hardness in both the coatings was attributed mainly to a reduction in crystallite size and decrease in surface roughness. The incorporation of Al into the CrN coatings has improved both hardness and Young’s modulus.

Keywords: CrN, AlCrN coatings, hardness, nanoindentation

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Authors: Ali Kadivar, Kaveh Niayesh

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This work simulates the voltage drop and resistance of the explosion of copper wires of diameters 25, 40, and 100 µm surrounded by 1 bar nitrogen exposed to a 150 A current and before plasma formation. The absorption of electrical energy in an exploding wire is greatly diminished when the plasma is formed. This study shows the importance of considering radiation and heat conductivity in the accuracy of the circuit simulations. The radiation of the dense plasma formed on the wire surface is modeled with the Net Emission Coefficient (NEC) and is mixed with heat conductivity through PLASIMO® software. A time-transient code for analyzing wire explosions driven by a slow current rise rate is developed. It solves a circuit equation coupled with one-dimensional (1D) equations for the copper electrical conductivity as a function of its physical state and Net Emission Coefficient (NEC) radiation. At first, an initial voltage drop over the copper wire, current, and temperature distribution at the time of expansion is derived. The experiments have demonstrated that wires remain rather uniform lengthwise during the explosion and can be simulated utilizing 1D simulations. Data from the first stage are then used as the initial conditions of the second stage, in which a simplified 1D model for high-Mach-number flows is adopted to describe the expansion of the core. The current was carried by the vaporized wire material before it was dispersed in nitrogen by the shock wave. In the third stage, using a three-dimensional model of the test bench, the streamer threshold is estimated. Electrical breakdown voltage is calculated without solving a full-blown plasma model by integrating Townsend growth coefficients (TdGC) along electric field lines. BOLSIG⁺ and LAPLACE databases are used to calculate the TdGC at different mixture ratios of nitrogen/copper vapor. The simulations show both radiation and heat conductivity should be considered for an adequate description of wire resistance, and gaseous discharges start at lower voltages than expected due to ultraviolet radiation and the exploding shocks, which may have ionized the nitrogen.

Keywords: exploding wire, Townsend breakdown mechanism, streamer, metal vapor, shock waves

Procedia PDF Downloads 81

Authors: Yongde Xia, Laicong Deng, Zhuxian Yang

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Developing cost-effective electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital in energy conversion and storage applications. Herein, we report a simple method for the synthesis of graphene-reinforced cobalt sulfide/carbon nanocomposites and the evaluation of their electrocatalytic performance for typical electrocatalytic reactions. Nanocomposites of cobalt sulfide embedded in N, S co-doped porous carbon and graphene (CoS@C/Graphene) were generated via simultaneous sulfurization and carbonization of one-pot synthesized graphite oxide-ZIF-67 precursors. The obtained CoS@C/Graphene nanocomposite was characterized by X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis-Mass spectroscopy, Scanning electronic microscopy, Transmission electronic microscopy, X-ray photoelectron spectroscopy and gas sorption. It was found that cobalt sulfide nanoparticles were homogenously dispersed in the in-situ formed N, S co-doped porous carbon/Graphene matrix. The CoS@C/10Graphene composite not only shows excellent electrocatalytic activity toward ORR with high onset potential of 0.89 V, four-electron pathway and superior durability of maintaining 98% current after continuously running for around 5 hours, but also exhibits good performance for OER and HER, due to the improved electrical conductivity, increased catalytic active sites and connectivity between the electrocatalytic active cobalt sulfide and the carbon matrix. This work offers a new approach for the development of novel multifunctional nanocomposites for the next generation of energy conversion and storage applications.

Keywords: MOF derivative, graphene, electrocatalyst, oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction

Procedia PDF Downloads 45

Authors: Paula Quiterio, Arlete Apolinario, Celia T. Sousa, Joao Azevedo, Paula Dias, Adelio Mendes, Joao P. Araujo

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Nowadays one of the mankind's greatest challenges has been the supply of low-cost and environmentally friendly energy sources as an alternative to non-renewable fossil fuels. Hydrogen has been considered a promising solution, representing a clean and low-cost fuel. It can be produced directly from clean and abundant resources, such as sunlight and water, using photoelectrochemical cells (PECs), in a process that mimics the nature´s photosynthesis. Hematite (alpha-Fe2O3) has attracted considerable attention as a promising photoanode for solar water splitting, due to its high chemical stability, nontoxicity, availability and low band gap (2.2 eV), which allows reaching a high thermodynamic solar-to-hydrogen efficiency of 16.8 %. However, the main drawbacks of hematite such as the short hole diffusion length and the poor conductivity that lead to high electron-hole recombination result in significant PEC efficiency losses. One strategy to overcome these limitations and to increase the PEC efficiency is to use 1D nanostructures, such as nanotubes (NTs) and nanowires (NWs), which present high aspect ratios and large surface areas providing direct pathways for electron transport up to the charge collector and minimizing the recombination losses. In particular, due to the ultrathin walls of the NTs, the holes can reach the surface faster than in other nanostructures, representing a key factor for the NTs photoresponse. In this work, we prepared hematite NWs and NTs, respectively by hydrothermal process and electrochemical anodization. For hematite NWs growing, we studied the effect of variable hydrothermal conditions, different annealing temperatures and time, and the use of Ti and Sn dopants on the morphology and PEC performance. The crystalline phase characterization by X-ray diffraction was crucial to distinguish the formation of hematite and other iron oxide phases, alongside its effect on the photoanodes conductivity and consequent PEC efficiency. The conductivity of the as-prepared NWs is very low, in the order of 10-5 S cm-1, but after doping and annealing optimization it increased by a factor of 105. A high photocurrent density of 1.02 mA cm-2 at 1.45 VRHE was obtained under simulated sunlight, which is a very promising value for this kind of hematite nanostructures. The stability of the photoelectrodes was also tested, presenting good stability after several J-V measurements over time. The NTs, synthesized by fast anodizations with potentials ranging from 20-100 V, presented a linear growth of the NTs pore walls, with very low thicknesses from 10 - 18 nm. These preliminary results are also very promising for the use of hematite photoelectrodes on PEC hydrogen applications.

Keywords: hematite, nanotubes, nanowires, photoelectrochemical cells

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Authors: Abazar Ghorbani, W. M. Wishwajith W. Kandegama, Seyed Mehdi Razavi, Moxian Chen

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The roles of hydrogen sulfide (H₂S) and melatonin (MT) as gasotransmitters in plants are widely recognised. Nevertheless, the precise nature of their involvement in defensive reactions remains uncertain. This study investigates the impact of the ML-H2S interaction on tomato plants exposed to vanadium (V) toxicity, focusing on synthesising secondary metabolites and V metal sequestration. The treatments applied in this study included a control (T1), V stress (T2), MT+V (T3), MT+H2S+V (T4), MT+hypotaurine (HT)+V (T5), and MT+H2S+HT+V (T6). These treatments were administered: MT (150 µM) as a foliar spray pre-treatment (3X), HT treatment (0.1 mM, an H2S scavenger) as root immersion for 12 hours as pre-treatments, and H2S (NaHS, 0.2 mM) and V (40 mg/L) treatments added to the Hoagland solution for 2 weeks. Results demonstrate that ML and H2S+ML treatments alleviate V toxicity by promoting the transcription of key genes (ANS, F3H, CHS, DFR, PAL, and CHI) involved in phenolic and anthocyanin biosynthesis. Moreover, they decreased V uptake and accumulation and enhanced the transcription of genes involved in glutathione and phytochelatin synthesis (GSH1, PCS, and ABC1), leading to V sequestration in roots and protection against V-induced damage. Additionally, ML and H2S+ML treatments optimize chlorophyll metabolism, and increase internal H2S levels, thereby promoting tomato growth under V stress. The combined treatment of ML+H2S shows superior effects compared to ML alone, suggesting synergistic/interactive effects between these two substances. Furthermore, inhibition of the beneficial impact of ML+H2S and ML treatments by HT, an H2S scavenger, underscores the significant involvement of H₂S in the signaling pathway activated by ML during V toxicity. Overall, these findings suggest that ML requires the presence of endogenous H₂S to mitigate V-induced adverse effects on tomato seedlings.

Keywords: vanadium toxicity, secondary metabolites, vanadium sequestration, h2s-melatonin crosstalk

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Authors: Ramasamy Tamizhselvi, Leema George, Madhav Bhatia

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We have earlier shown that mouse pancreatic acinar cells produce hydrogen sulfide (H2S) and play a role in the pathogenesis of acute pancreatitis. This study is to determine the effect of H2S on TLR4 mediated innate immune signaling in acute pancreatitis via substance P (SP). Male Swiss mice were treated with hourly intraperitoneal injection of caerulein (50μg/kg) for 10 hour. DL-propargylglycine (PAG) (100 mg/kg i.p.), an inhibitor of H2S formation was administered 1h after the induction of acute pancreatitis. Pancreatic acinar cells from male Swiss mice were incubated with or without caerulein (10–7 M for 60 min) and CP-96345 (NK1R inhibitor). To better understand the effect of H2S in inflammation, acinar cells were stimulated with caerulein after addition of H2S donor, NaHS. In addition, caerulein treated pancreatic acinar cells were pretreated with PAG (30 µM), for 1h. H2S inhibitor, PAG, eliminated TLR4, IRAK4, TRAF6 and NF-kB levels in an in vitro and in vivo model of caerulein-induced acute pancreatitis. PPTA gene deletion reduced TLR4, MyD88, IRAK4, TRAF6, adhesion molecules and NF-kB in caerulein treated pancreatic acinar cells whereas administration of NaHS resulted in further rise in TLR4 and NF-kB levels in caerulein treated pancreatic acinar cells. In addition, acini isolated from mice and treated with PPTA gene receptor NK1R antagonist CP96345 did not exhibit further increase in TLR4, IRAK4, TRAF6, adhesion molecules and NF-kB levels after NaHS pretreatment. The present findings show for the first time that in acute pancreatitis, H2S up-regulates TLR4 pathway and NF-kB via substance P.

Keywords: preprotachykinin-A gene, H2S, TLR4, acute pancreatitis

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Authors: A. Alharbi, R. Boukhanouf, T. Habeebullah, H. Ibrahim

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This paper presents a detailed description of evaporative cooling systems used for space cooling in Mina Valley, Saudi Arabia. The thermal performance and environmental impact of the evaporative coolers were evaluated. It was found that the evaporative cooling systems used for space cooling in pilgrims’ accommodations and in the train stations could reduce energy consumption by as much as 75% and cut carbon dioxide emission by 78% compared to traditional vapour compression systems.

Keywords: evaporative cooling, vapor compression, electricity consumption, CO2 emission

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Authors: K. Parthiban, P. Pradeep, I. Pon Surya Prakash, S. Vinoth, A. Murugan

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The main aim of this project is to analyze the performance of vapor compression refrigeration system with alternate refrigerants. Currently we are using R134a as refrigerant. It is used in both household and industrial appliances as refrigerant. It has an advantage that the ozone depletion potential is zero i.e. R134a does not affects ozone layer. But its Global warming potential is considerably high. Also the compressor failure occurs frequently. Hence this project deals with how the performance of R134a varies with blended refrigerants such as R416a and R407c. This analysis is based on how much the Co-efficient of Performance (COP) varies with different refrigerants.

Keywords: compressor, condenser, expansion valve, evaporator

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Authors: A. Bouloufa, K. Djessas

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In this paper, we reported the effect of substrate temperature on the structural, electrical and optical properties of In2S3 thin films deposited on soda-lime glass substrates by physical vapor deposition technique at various substrate temperatures. The In2Se3 material used for deposition was synthesized from its constituent elements. It was found that all samples exhibit one phase which corresponds to β-In2S3 phase. Values of band gap energy of the films obtained at different substrate temperatures vary in the range of 2.38-2.80 eV and decrease with increasing substrate temperature.

Keywords: buffer layer, In2S3, optical properties, PVD, structural properties

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Authors: Michella Alnajjar, Frederic Christien, Krzysztof Wolski, Cedric Bosch

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Additive manufacturing (AM) has gained more interest in the past few years because it allows 3D parts often having a complex geometry to be directly fabricated, layer by layer according to a CAD model. One of the AM techniques is the selective laser melting (SLM) which is based on powder bed fusion. In this work, the corrosion resistance of 17-4 PH steel obtained by SLM is investigated. Wrought 17-4 PH steel is a martensitic precipitation hardenable stainless steel. It is widely used in a variety of applications such as aerospace, medical and food industries, due to its high strength and relatively good corrosion resistance. However, the combined findings of X-Ray diffraction and electron backscatter diffraction (EBSD) proved that SLM-ed 17-4 PH steel has a fully ferritic microstructure, more specifically δ ferrite. The microstructure consists of coarse ferritic grains elongated along the build direction, with a pronounced solidification crystallographic texture. These results were associated with the high cooling and heating rates experienced throughout the SLM process (10⁵-10⁶ K/s) that suppressed the austenite formation and produced a 'by-passing' phenomenon of this phase during the numerous thermal cycles. Furthermore, EDS measurements revealed a uniform distribution of elements without any dendritic structure. The extremely high cooling kinetics induced a diffusionless solidification, resulting in a homogeneous elemental composition. Consequently, the corrosion properties of this steel are altered from that of conventional ones. By using electrochemical means, it was found that SLM-ed 17-4 PH is more resistant to general corrosion than the wrought steel. However, the SLM-ed material exhibits metastable pitting due to its high porosity density. In addition, the hydrogen embrittlement of SLM-ed 17-4 PH steel is investigated, and a correlation between its behavior and the observed microstructure is made.

Keywords: corrosion resistance, 17-4 PH stainless steel, selective laser melting, hydrogen embrittlement

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Authors: M. Kowalik, J. Masternak, K. Kazimierczuk, O. V. Khavryuchenko, B. Kupcewicz, B. Barszcz

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Recently, the growing interest of chemists in metal-organic coordination polymers (MOCPs) is primarily derived from their intriguing structures and potential applications in catalysis, gas storage, molecular sensing, ion exchanges, nonlinear optics, luminescence, etc. Currently, we are devoting considerable effort to finding the proper method of synthesizing new coordination polymers containing S- or N-heteroaromatic carboxylates as linkers and characterizing the obtained Pb(II) compounds according to their structural diversity, luminescence, and thermal properties. The choice of Pb(II) as the central ion of MOCPs was motivated by several reasons mentioned in the literature: i) a large ionic radius allowing for a wide range of coordination numbers, ii) the stereoactivity of the 6s2 lone electron pair leading to a hemidirected or holodirected geometry, iii) a flexible coordination environment, and iv) the possibility to form secondary bonds and unusual non-covalent interactions, such as classic hydrogen bonds and π···π stacking interactions, as well as nonconventional hydrogen bonds and rarely reported tetrel bonds, Pb(lone pair)···π interactions, C–H···Pb agostic-type interactions or hydrogen bonds, and chelate ring stacking interactions. Moreover, the construction of coordination polymers requires the selection of proper ligands acting as linkers, because we are looking for materials exhibiting different network topologies and fluorescence properties, which point to potential applications. The reaction of Pb(NO₃)₂ with 1H-pyrrole-2-carboxylic acid (2prCOOH) leads to the formation of a new four-nuclear Pb(II) polymer, [Pb4(2prCOO)₈(H₂O)]ₙ, which has been characterized by CHN, FT-IR, TG, PL and single-crystal X-ray diffraction methods. In view of the primary Pb–O bonds, Pb1 and Pb2 show hemidirected pentagonal pyramidal geometries, while Pb2 and Pb4 display hemidirected octahedral geometries. The topology of the strongest Pb–O bonds was determined as the (4·8²) fes topology. Taking the secondary Pb–O bonds into account, the coordination number of Pb centres increased, Pb1 exhibited a hemidirected monocapped pentagonal pyramidal geometry, Pb2 and Pb4 exhibited a holodirected tricapped trigonal prismatic geometry, and Pb3 exhibited a holodirected bicapped trigonal prismatic geometry. Moreover, the Pb(II) lone pair stereoactivity was confirmed by DFT calculations. The 2D structure was expanded into 3D by the existence of non-covalent O/C–H···π and Pb···π interactions, which was confirmed by the Hirshfeld surface analysis. The above mentioned interactions improve the rigidity of the structure and facilitate the charge and energy transfer between metal centres, making the polymer a promising luminescent compound.

Keywords: coordination polymers, fluorescence properties, lead(II), lone electron pair stereoactivity, non-covalent interactions

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Authors: Ene Rosemary Ndidiamaka, Nwangwu Florence Chinyere

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The physiochemical properties of the melon seed oil was studied to determine its potentials as viable feed stock for biodisel production. The melon seed was extracted by solvent extraction using n-hexane as the extracting solvent. In this research, methanol was the alcohol used in the production of biodiesel, although alcohols like ethanol, propanol may also be used. Sodium hydroxide was employed for the catalysis. The melon seed oil was characterized for specific gravity, pH, ash content, iodine value, acid value, saponification value, peroxide value, free fatty acid value, flash point, viscosity, and refractive index using standard methods. The melon seed oil had very high oil content. Specific gravity and flash point of the oil is satisfactory. However, moisture content of the oil exceeded the stipulated ASRTM standard for biodiesel production. The overall results indicates that the melon seed oil is suitable for single-stage transesterification process to biodiesel production.

Keywords: biodiesel, catalyst, melon seed, transesterification

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Authors: Shengjun Zhang, Xu Cheng, Feng Shen

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The passive containment cooling system (PCCS) is widely used in the advanced nuclear reactor in case of the loss of coolant accident (LOCA) and the main steam line break accident (MSLB). The internal heat exchanger is one of the most important equipment in the PCCS and its heat transfer characteristic determines the performance of the system. In this investigation, a theoretical model is presented for predicting the heat and mass transfer which accompanies condensation. The conduction through the liquid condensate is considered and the interface temperature is defined by iteration. The parameter in the correlation to describe the suction effect should be further determined through experimental data.

Keywords: non-condensable gas, condensation, heat transfer coefficient, heat and mass transfer analogy

Procedia PDF Downloads 344

Authors: Sylwia K. Naliwajko, Justyna Moskwa, Patryk Nowakowski, Renata Markiewicz-Zukowska, Krystyna Gromkowska-Kepka, Anna Puscion-Jakubik, Maria H. Borawska

Abstract:

Amygdalin is found in many fruit seeds, including apricot, peach, quince, apples, and almonds. Amygdalin (also named vitamin B17), as well as its sources, are commonly used as an alternative therapy or prevention of cancer. The potential activity of amygdalin is related to its enzymatic degradation to the hydrogen cyanide. Hydrogen cyanide is a toxic substance that causes liver and nerves damage, fever, coma or even death. Amygdalin is much better tolerated after intravenous than oral administration. The aim of this study was to examine the influence of amygdalin on glioblastoma multiforme cell lines. Three glioblastoma multiforme cell lines – U87MG, T98, LN18 were incubated (48 h) with amygdalin in concentrations 100, 250, 500, 1000 and 2000 µg/mL. The MTT (Thiazolyl Blue Tetrazolium Bromide) test and DNA binding test by [3H]-thymidine incorporation were used to determine the anti-proliferative activity of amygdalin. The secretion of metalloproteinases (MMP2 and MMP-9) from U87MG cells was estimated by gelatin zymography. The statistical analysis was performed using Statistica v. 13.0 software. The data was presented as a % of control. Amygdalin did not show significant inhibition of viability of all the glioblastoma cells in concentrations 100, 250, 500, 1000 µg/mL. In 2000 µg/mL there were significant differences compared to the control, but inhibition of viability was less than 20% (more than 80% of control). The average viability of U87MG cells was 92,0±4%, T98G: 85,8±3% and LN18: 94,7±2% of the control. There was no dose-response viability, and IC50 value was not recognized. DNA binding in U87MG cells was not inhibited (109,0±3 % of control). After treatment with amygdalin, we observed significantly increased secretion of MMP2 and MMP9 in U87MG cells (130,3±14% and 112,0±5% of control, respectively). Our results suggest that amygdalin has no anticancer activity in glioblastoma cell lines.

Keywords: amygdalin, anticancer, cell line, glioblastoma

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Authors: N. I. Kargin, G. K. Safaraliev, A. S. Gusev, A. O. Sultanov, N. V. Siglovaya, S. M. Ryndya, A. A. Timofeev

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In this paper, an experimental and theoretical study of the processes of mesoporous silicon carbonization during the formation of buffer layers for the subsequent epitaxy of 3C-SiC films and related wide-band-gap semiconductors is performed. Experimental samples were obtained by the method of chemical vapor deposition and investigated by scanning electron microscopy. Analytic expressions were obtained for the effective diffusion factor and carbon atoms diffusion length in a porous system. The proposed model takes into account the processes of Knudsen diffusion, coagulation and overgrowing of pores during the formation of a silicon carbide layer.

Keywords: silicon carbide, porous silicon, carbonization, electrochemical etching, diffusion

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Authors: Mehran Nozari-Asbemarz, Italo Pisano, Simin Arshi, Edmond Magner, James J. Leahy

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Integrating electrolytic synthesis with renewable energy makes it feasible to address urgent environmental and energy challenges. Conventional water electrolyzers concurrently produce H₂ and O₂, demanding additional procedures in gas separation to prevent contamination of H₂ with O₂. Moreover, the oxygen evolution reaction (OER), which is sluggish and has a low overall energy conversion efficiency, does not deliver a significant value product on the electrode surface. Compared to conventional water electrolysis, integrating electrolytic hydrogen generation from water with thermodynamically more advantageous aqueous organic oxidation processes can increase energy conversion efficiency and create value-added compounds instead of oxygen at the anode. One strategy is to use renewable and sustainable carbon sources from biomass, which has a large annual production capacity and presents a significant opportunity to supplement carbon sourced from fossil fuels. Numerous catalytic techniques have been researched in order to utilize biomass economically. Because of its safe operating conditions, excellent energy efficiency, and reasonable control over production rate and selectivity using electrochemical parameters, electrocatalytic upgrading stands out as an appealing choice among the numerous biomass refinery technologies. Therefore, we propose a broad framework for coupling H2 generation from water splitting with oxidative biomass upgrading processes. Four representative biomass targets were considered for oxidative upgrading that used a hierarchically porous CoFe-MOF/LDH @ Graphite Paper bifunctional electrocatalyst, including glucose, ethanol, benzyl, furfural, and 5-hydroxymethylfurfural (HMF). The potential required to support 50 mA cm-2 is considerably lower than (~ 380 mV) the potential for OER. All four compounds can be oxidized to yield liquid byproducts with economic benefit. The electrocatalytic oxidation of glucose to the value-added products, gluconic acid, glucuronic acid, and glucaric acid, was examined in detail. The cell potential for combined H₂ production and glucose oxidation was substantially lower than for water splitting (1.44 V(RHE) vs. 1.82 V(RHE) for 50 mA cm-2). In contrast, the oxidation byproduct at the anode was significantly more valuable than O₂, taking advantage of the more favorable glucose oxidation in comparison to the OER. Overall, such a combination of HER and oxidative biomass valorization using electrocatalysts prevents the production of potentially explosive H₂/O₂mixtures and produces high-value products at both electrodes with lower voltage input, thereby increasing the efficiency and activity of electrocatalytic conversion.

Keywords: biomass, electrocatalytic, glucose oxidation, hydrogen evolution

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Authors: Sourav Ray, Christoph Stein, Marcus Weber

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A new class of drug candidates, initially derived from mathematical modeling of ligand-receptor interactions, activate the μ-opioid receptor (MOR) preferentially at acidic extracellular pH-levels, as present in injured tissues. This is of commercial interest because it may preclude the adverse effects of conventional MOR agonists like fentanyl, which include but are not limited to addiction, constipation, sedation, and apnea. Animal studies indicate the importance of taking the pH value of the chemical environment of MOR into account when designing new drugs. Hydrogen bonds (HBs) play a crucial role in stabilizing protein secondary structure and molecular interaction, such as ligand-protein interaction. These bonds may depend on the pH value of the chemical environment. For the MOR, antagonist naloxone and agonist [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAMGO) form HBs with ionizable residue HIS 297 at physiological pH to modulate signaling. However, such interactions were markedly reduced at acidic pH. Although fentanyl-induced signaling is also diminished at acidic pH, HBs with HIS 297 residue are not observed at either acidic or physiological pH for this strong agonist of the MOR. Molecular dynamics (MD) simulations can provide greater insight into the interaction between the ligand of interest and the HIS 297 residue. Amino acid protonation states are adjusted to the model difference in system acidity. Unbiased and unrestrained MD simulations were performed, with the ligand in the proximity of the HIS 297 residue. Ligand-receptor complexes were embedded in 1-palmitoyl-2-oleoyl-sn glycero-3-phosphatidylcholine (POPC) bilayer to mimic the membrane environment. The occurrence of HBs between the different ligands and the HIS 297 residue of MOR at acidic and physiological pH values were tracked across the various simulation trajectories. No HB formation was observed between fentanyl and HIS 297 residue at either acidic or physiological pH. Naloxone formed some HBs with HIS 297 at pH 5, but no such HBs were noted at pH 7. Interestingly, DAMGO displayed an opposite yet more pronounced HB formation trend compared to naloxone. Whereas a marginal number of HBs could be observed at even pH 5, HBs with HIS 297 were more stable and widely present at pH 7. The HB formation plays no and marginal role in the interaction of fentanyl and naloxone, respectively, with the HIS 297 residue of MOR. However, HBs play a significant role in the DAMGO and HIS 297 interaction. Post DAMGO administration, these HBs might be crucial for the remediation of opioid tolerance and restoration of opioid sensitivity. Although experimental studies concur with our observations regarding the influence of HB formation on the fentanyl and DAMGO interaction with HIS 297, the same could not be conclusively stated for naloxone. Therefore, some other supplementary interactions might be responsible for the modulation of the MOR activity by naloxone binding at pH 7 but not at pH 5. Further elucidation of the mechanism of naloxone action on the MOR could assist in the formulation of cost-effective naloxone-based treatment of opioid overdose or opioid-induced side effects.

Keywords: effect of system acidity, hydrogen bond formation, opioid action, receptor activation

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Authors: Abhishek Kumar Gupta

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Atomistic Molecular Dynamics (MD) Simulations have been performed to study the effect of monovalent salt i.e. NaCl concentration (Cs) and chain degree of neutralization (f) on the structure and dynamics of anionic poly(methacrylic acid) (PMA) in dilute aqueous solutions. In the present study, the attention is to unveil the conformational structure, hydrogen-bonding, local polyion-counterion structure, h-bond dynamics, chain dynamics and thermodynamic enthalpy of solvation of a-PMA in dilute aqueous solutions as a function of salt concentration, Cs and f. The results have revealed that at low salt concentration, the conformational radius of gyration (Rg) increases and then decreases reaching a maximum in agreement with the reported light scattering experimental results. The Rg at f = 1 shows a continual decrease and acquire a plateau value at higher salt concentration in agreement with results obtained by light scattering experiments. The radial distribution functions between PMA, salt and water atoms has been computed with respect to atom and centre-of-mass to understand the intermolecular structure in detail. The results pertaining to PMA chain conformations and hydrogen bond autocorrelation function showcasing the h-bond dynamics will be presented. The results pertaining to chain dynamics will be presented. The results pertaining to counterion condensation on the PMA chain shows greater condensation of Na+ ions on to the carboxylate ions with increase in salt concentration. Moreover, the solvation enthalpy of the system as a function of salt concentration will be presented.

Keywords: conformations, molecular dynamics simulations, NaCl concentration, radial distribution functions

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Authors: Nur Suraya Anis Ahmad Bakhtiar, Hazizan Md Akil

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In the present work, the dielectric properties of Epoxy/MWCNTs-muscovite HYBRID and MIXED composites based on ratio 30:70 were studies. The multi-wall carbon nanotubes (MWCNTs) were prepared by two method; (a) muscovite-MWCNTs hybrids were synthesized by chemical vapor deposition (CVD) and (b) physically mixing of muscovite with MWCNTs. The effect of different preparations of the composites and filler loading was evaluated. It is revealed that the dielectric constants of HYBRID epoxy composites are slightly higher compared to MIXED epoxy composites. It is also indicated that the dielectric constant increased by increases the MWCNTs filler loading.

Keywords: muscovite, epoxy, dielectric properties, hybrid composite

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Authors: Omar Omar, Yuan Jun, Hong Jinghua, Jin Chuanhong

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In this work molybdenum dioxide (MoO2) and sulphur powders are used to grow MoS2 mono layers at elevated temperatures T≥800 °C. Centimetre scale continues thin films with grain size up to 410 µm have been grown using chemical vapour deposition. To our best knowledge, these domains are the largest that have been grown so far. Advantage of our approach is not only because of the high quality films with large domain size one can produce, but also the procedure is potentially less hazardous than other methods tried. The thin films have been characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy.

Keywords: molybdenum disulphide (MoS2), monolayers, chemical vapour deposition (CVD), growth and characterization

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Authors: Mahendra Singh, Narasimhareddy Ravuru

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For the past decade, the production of biodiesel has significantly increased along with its by-product, glycerol. Biodiesel-derived glycerol massive entry into the glycerol market has caused its value to plummet. Newer ways to utilize the glycerol by-product must be implemented or the biodiesel industry will face serious economic problems. The biodiesel industry should consider steam reforming glycerol to produce hydrogen gas. Steam reforming is the most efficient way of producing hydrogen and there is a lot of demand for it in the petroleum and chemical industries. This study investigates the feasibility of glycerol steam reforming in an industrial sized fixed bed reactor. In this paper, using computational fluid dynamic (CFD) simulations, the extent of the transport resistances that would occur in an industrial sized reactor can be visualized. An important parameter in reactor design is the size of the catalyst particle. The size of the catalyst cannot be too large where transport resistances are too high, but also not too small where an extraordinary amount of pressure drop occurs. The goal of this paper is to find the best catalyst size under various flow rates that will result in the highest conversion. Computational fluid dynamics simulated the transport resistances and a pseudo-homogenous reactor model was used to evaluate the pressure drop and conversion. CFD simulations showed that glycerol steam reforming has strong internal diffusion resistances resulting in extremely low effectiveness factors. In the pseudo-homogenous reactor model, the highest conversion obtained with a Reynolds number of 100 (29.5 kg/h) was 9.14% using a 1/6 inch catalyst diameter. Due to the low effectiveness factors and high carbon deposition rates, a fluidized bed is recommended as the appropriate reactor to carry out glycerol steam reforming.

Keywords: computational fluid dynamic, fixed bed reactor, glycerol, steam reforming, biodiesel

Procedia PDF Downloads 300