Open Atmospheric Conditions Research Articles

Carbon and oxygen isotopic composition of coal and carbon dioxide derived from laboratory coal combustion: A preliminary study

The concentration of carbon dioxide (CO2) in the atmosphere has dramatically increased from the start of the industrial revolution in the mid-1700s to present levels exceeding 400ppm. Carbon dioxide derived from fossil fuel combustion is a greenhouse gas and a major contributor to on-going climate change. Carbon and oxygen stable isotope geochemistry is a useful tool to help model and predict the contributions of anthropogenic sources of CO2 in the global carbon cycle. Surprisingly few studies have addressed the carbon and oxygen isotopic composition of CO2 derived from coal combustion. The goal of this study is to document the relationships between the carbon and oxygen isotope signatures of coal and signatures of the CO2 produced from laboratory coal combustion in atmospheric conditions.Six coal samples were selected that represent various geologic ages (Carboniferous to Tertiary) and coal ranks (lignite to bituminous). Duplicate splits of the six coal samples were ignited and partially combusted in the laboratory at atmospheric conditions. The resulting coal-combustion gases were collected and the molecular composition of the collected gases and isotopic analyses of δ13C of CO2, δ13C of CH4, and δ18O of CO2 were analysed by a commercial laboratory. Splits (~1g) of the un-combusted dried ground coal samples were analyzed for δ13C and δ18O by the U.S. Geological Survey Reston Stable Isotope Laboratory.The major findings of this preliminary work indicate that the isotopic signatures of δ13C (relative to the Vienna Pee Dee Belemnite scale, VPDB) of CO2 resulting from coal combustion are similar to the δ13CVPDB signature of the bulk coal (−28.46 to −23.86‰) and are not similar to atmospheric δ13CVPDB of CO2 (~−8‰, see http://www.esrl.noaa.gov/gmd/outreach/isotopes/c13tellsus.html). The δ18O values of bulk coal are strongly correlated to the coal dry ash yields and appear to have little or no influence on the δ18O values of CO2 resulting from coal combustion in open atmospheric conditions. There is a wide range of δ13C values of coal reported in the literature and the δ13C values from this study generally follow reported ranges for higher plants over geologic time. The values of δ18O (relative to Vienna Standard Mean Ocean Water) of CO2 derived from atmospheric combustion of coal and other high-carbon fuels (peat and coal) range from +19.03 to +27.03‰ and are similar to atmospheric oxygen δ18OVSMOW values which average +23.8‰. Further work is needed on a broader set of samples to better define the relationships between coal composition and combustion-derived gases.

A newly composed paraffin encapsulated prototype roof structure for efficient thermal management in hot climate

For efficient thermal management in the building under hot weather condition a new paraffin composition as suitable PCM is needed. Several notable attributes of paraffin wax including thermo-physical properties, open air atmospheric condition, economy, and environmental amiability make them suitable PCM for incorporation in the building. Thus, new PCM with massive storage of heat or cold in a specific volume is demanded. Iraqi local paraffin waxes as PCM are proven to be highly prospective due to their high-vitality thickness and isothermal conduct. However, thermal performance optimization of new PCM is pre-requisite to determine its effectiveness in hot climate location. We prepare three new PCM compositions with different oil to wax ratios from the crude petrochemical feed stock waste using fractionation followed by de-waxing and crystallization. The melting temperatures and flash points of these paraffin waxes are ranged between 19 and 44 °C and 177–256 °C, respectively, which upon encapsulation in the prototype roof construction are demonstrated to produce thermal comfort in rooms under hot climate (Iraq). Furthermore, these indigenous PCMs (local paraffin) are abundant, environmental friendly, economic and save electricity cost and HVAC (heating-ventilating air conditioning) systems. Experimental results displayed much reduced temperature fluctuation and internal heat flux of the prototype room than the commercial PCMs. Temperature profiles and solar irradiances inside the room on hot summer days in Bagdad showed remarkable electricity saving. This newly extracted PCM being non-flammable and thermally comfortable are truly secure for buildings construction worldwide.

Phase Change Materials-Assisted Heat Flux Reduction: Experiment and Numerical Analysis

Phase change materials (PCM) in the construction industry became attractive because of several interesting attributes, such as thermo-physical parameters, open air atmospheric condition usage, cost and the duty structure requirement. Thermal performance optimization of PCMs in terms of proficient storage of a large amount of heat or cold in a finite volume remains a challenging task. Implementation of PCMs in buildings to achieve thermal comfort for a specific climatic condition in Iraq is our main focus. From this standpoint, the present paper reports the experimental and numerical results on the lowering of heat flux inside a residential building using PCM, which is composed of oil (40%) and wax (60%). This PCM (paraffin), being plentiful and cost-effective, is extracted locally from waste petroleum products in Iraq. Experiments are performed with two rooms of identical internal dimensions in the presence and absence of PCM. A two-dimensional numerical transient heat transfer model is developed and solved using the finite difference method. A relatively simple geometry is chosen to initially verify the numerical solution procedure by incorporating in the computer program two-dimensional elliptic flows. It is demonstrated that the heat flux inside the room containing PCM is remarkably lower than the one devoid of PCM.

Superior texture-controlled ZnO thin film using electrochemical deposition

Superior texture-controlled ZnO thin film is prepared using a low cost electrochemical deposition process at open atmospheric condition. FE-SEM shows that the surface morphology can be altered from nanorods to microplates by adding a chemical additive. XRD analysis confirms that the crystalline growth direction and texture can be controlled by changing the additive concentration during the deposition. Using the optimized ZnO based back reflector (BR) in single junction a-SiGe:H solar cell device, we have achieved external quantum efficiency (EQE) as high as 87% at ∼550nm; the EQE corrected short circuit current density (JSC) was 20.63mAcm−2 and solar cell efficiency was 7.73% for the single junction a-SiGe:H solar cell. It proves to us that the high quality ZnO thin films can be produced at much reduced cost using electrochemical deposition for solar cell and other optoelectronic applications.

Influence of self-protective atmosphere in fiber laser welding of austenitic stainless steel

The thermo-chemical reactions between working atmosphere and molten weld pool in fusion welding process severely affect the weld joint quality and weld metal properties. Hence, the welding atmosphere plays a significant role to decide the weld joint quality. Fiber laser source is popularly being used in recent past over Nd:YAG, CO2, and diode lasers due to characteristic advantages of compact size, high stability and reliability, and deeper penetration. In present work, the characteristic difference between a self-protective atmosphere of argon and open atmosphere have been investigated during fiber laser welding of austenitic stainless steel. A mixed mode beam power of a 2-kW ytterbium fiber laser has been used to conduct the experiments. The characteristic variation in terms of weld pool size and shape, weld bead quality, and top surface profile at various process parameters are analyzed. The experiments are conducted at 800 and 1000-W laser power and 13.33 to 18.33-mm/s laser scanning speed. The study indicates that aspect ratio as well as weld depth of penetration in a self-protective atmosphere of argon is more as compared to open atmospheric condition. The appearance of top surface profile in case of self-protective atmosphere is far better than open atmospheric conditions. Furthermore, a three-dimensional non-linear transient heat transfer model is developed to compute the weld pool dimensions using a Gaussian-distributed volumetric heat source. The result demonstrates that the numerically computed weld pool shape and size are in a fair agreement with experimentally measured macrographs.

Synthesis, crystal structure, bioactivities of Ni(II), Cu(II), Co(II) and Pd(II) complexes with unsymmetrical thioether donor Schiff base: Phosphine free Pd(II) complex catalyzed Suzuki reaction

A series of new Ni(II), Cu(II), Co(II) and Pd(II) complexes were synthesized from the reaction of thioether containing Schiff base ligand with corresponding metal salts by a simple environmentally benign procedure. The molecular formulae of ligand and their complexes are (C21H19NO2S)2,1, [Ni(C21H18NO2S)2]·CH3OH·H2O,2, [M(C21H18NO2S)2] (3 and 4), where (M=Cu(II) and Co(II)) and [Pd(C21H18NO2SCl)](5). All complexes were characterized by elemental analysis, FT-IR, UV–Vis spectroscopy and single crystal X-ray diffraction analysis. The ligand was characterized by same techniques and with 1H NMR spectroscopy. X-ray diffraction study reveals that copper complex adopts square planar geometry by coordinating via deprotonated hydroxyl oxygen, azomethine nitrogen of ligand to the copper centre and sulfur atoms remain unligated. As expected, nickel complex acquired a distorted octahedral geometry coordinating via deprotonated hydroxyl oxygen, azomethine nitrogen and thioether sulfur atoms of ligands. Interestingly, one water and one methanol molecule are attached at the out sphere of the nickel complex. Suzuki reaction was carried out in open atmospheric conditions using palladium complex as catalyst. The significant features of the palladium complex catalyzed reaction are good yield, simple workup procedure, easy purification and easy recovery technique of the catalyst. The reported palladium complex is phosphine free, air stable, moisture insensitive. The ligand and complexes show very good biological activities against Mycobacterium abscessus, Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris, Mycobacterium smegmatis and Escherichia coli.

A highly thermally stable Mn–Cu–Fe composite oxide based solar selective absorber layer with low thermal loss at high temperature

A highly thermally stable Mn–Cu–Fe composite oxide based solar selective absorber layer for high temperature applications has been developed on a special variety of alloy substrate (SS-J4) using an economical process of controlled thermal oxidation. This novel type of composite oxide layer exhibits a high thermal stability and low emissive property even in an open air atmospheric condition. It is very contrary from previously known selective solar absorber coatings exhibited strong thermal stability along with low emissive property only in the vacuum environment. A solar absorptance of 91.5% (αAM1.5; 300–2400nm) and a spectral emittance of 0.14 (3–25μm) have been achieved for an absorber layer developed by the best optimised conditions. An open air high temperature cyclic test of the optimised composite layer was also investigated at 500°C and the stability of the coatings with respect to optical properties was established. Moreover, a constant value of thermal emissivity, 0.19 at 500°C, was measured repeatedly by the thermal emittance measurement as well as a low value of performance criterion (PC), <0.01, was calculated after thermal cycle test, indicating a high thermal stability and long durability of the absorber layer.

Synthesis, characterization and time dependent phase transformation of Li0.4WO3 bronze

Abstract Lithium tungsten bronzes with a nominal composition of Li0.4WO3 were synthesized by solid state reactions in silica tubes at 973 K and various low pressures. Samples were characterized using X-ray single crystal and powder diffraction, and neutron powder diffraction. The air pressure inside the sealed quartz tubes played roles for the formation of Li0.4WO3 phases with different symmetries. Whereas using a pressure of 10–7 MPa a pure body centered cubic (Im 3 ¯ $\bar 3$ ) tungsten bronze was formed, at higher pressures (&gt;10–7 MPa) a mixture of Im 3 ¯ $\bar 3$ and primitive cubic (Pm 3 ¯ $\bar 3$ m) perovskite tungsten bronzes were observed with pressure dependent phase fractions. While keeping the synthesized samples under open atmospheric conditions the Im 3 ¯ $\bar 3$ phase gradually transformed into a tetragonal perovskite (P4/nmm) tungsten bronze. The slow cubic into tetragonal phase transformation has been explained in terms of the mobility of lithium within two different crystallographic sites.

Optimisation of Experimental Techniques to Enhance the Efficiency of Polymer Photovoltaic Cell

The idea of generating electricity from plastics itself sounds enthralling, but it is equally challenging to achieve in the lab and then take it to the production level. Polymer Solar Cells (PSCs) have the advantage of lower cost and flexibility but they do suffer from problems like low efficiency and smaller service life which is mainly due to limited absorption spectra, poor charge mobility and the degradation of the polymers. A combination of narrow band donor and fullerene derivative is one of the possible approaches to fabricate a working device. In this work, various experimental techniques have been optimised in order to achieve better efficiency of the PSCs in atmospheric condition. Optimized parameters from polymer mixing ratio, spin coating, annealing and others were used to enhance efficiency of device. Parameters were optimized with the help various techniques viz. Viscometer, Thermo Gravity Analysis, UV-vis spectroscopy, Scanning Electron Microscopy and I-V measurement system. We report 0.76% efficiency in these solar cells, which were fabricated in open atmospheric condition. The as-prepared device showed a good performance with an open-circuit voltage (Voc) 0.74 V, short circuit current (Isc) 0.6 mA, a fill factor (FF) of 35%.

Characterization of Ni–YSZ anodes for solid oxide fuel cells fabricated by suspension plasma spraying with axial feedstock injection

Composite Ni–Y0.15Zr0.85O1.925 anodes were fabricated by axial-injection suspension plasma spraying in open atmosphere conditions. The composition of the anode is controllable by adjustment of the plasma gas composition, stand-off distance, and suspension feed rate. The total porosity is controllable through the addition of carbon black to the suspension as a sacrificial pore-forming material as well as by adjustment of the suspension feed rate. The size of the NiO particles in suspension affects both the composition and total porosity, with larger NiO particles leading to increased Ni content and porosity in the deposited coatings. The surface roughness increases with a decrease of the in-flight droplet momentum, which results from both smaller NiO particles in suspension and the addition of low density pore-forming materials. A solid oxide fuel cell was fabricated with both electrodes and electrolyte fabricated by axial-injection plasma spraying. Peak power densities of 0.718 W cm−2 and 1.13 W cm−2 at 750 °C and 850 °C, respectively, were achieved.

Surface Modification of Steels Using Friction Stir Surfacing

Friction stir surfacing is done to deposit commercial pure Al on medium carbon steel under open atmosphere conditions. Roughness of the substrate, normal load and tool rotation are the variables. Deposition is analysed with respect to continuity, width, composition and phase parameters. Good deposition is observed under a limited set of load and rotation speed. The deposit contains a mixture of steel and aluminium particles.

Template-Free Synthesis of Self-Assembled Co&lt;SUB&gt;3&lt;/SUB&gt;O&lt;SUB&gt;4&lt;/SUB&gt; Micro/Nanocrystals

In this article, we have reported the fabrication of various morphological porous Co3O4 by thermal decomposition of cobalt oxalate at open atmospheric conditions. Uniform cobalt oxalate microrods and microneedles were synthesized without using any surfactants or templates in large scale. The cobalt oxalate preparation method was played a crucial role on the crystal structure and its morphology. The as prepared cobalt oxalates and its corresponding cobalt oxides were characterized by using the thermogravimetric analysis, X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM) and nitrogen adsorption analysis. The XRD results indicated that the orthorhombic and monoclinic cobalt oxalates were formed in different experimental conditions. The influence of preparation method of cobalt oxalates and cobalt precursors on the final morphology has been investigated. The M-H loop of the Co3O4 porous microrods and microneedles showed the presence of paramagnetic properties at room temperatures. A plausible mechanism of both cobalt oxalates and Co3O4 formation was proposed based on the experimental results.

Synthesis of visible light responsive ZnO–ZnS/C photocatalyst by simple carbothermal reduction

A new visible light responsive ZnO–ZnS/C photocatalysts have been successfully synthesized by a simple heat-treating procedure using ZnSO4 as single precursor for the first time. The resultant samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and BET surface area measurement. The results showed that the ZnO–ZnS/C catalysts were directly formed by thermal decomposition of ZnSO4 impregnated on the activated carbon at high temperature under open atmospheric conditions. Here, a possible growth mechanism of the coupled ZnO–ZnS/C photocatalysts was proposed. Activated carbon played both reducing agent and support role in formation of ZnO–ZnS/C catalysts. The photocatalytic activities of catalysts were investigated by degrading reactive brilliant blue K-3R under visible light irradiation. The synthesized catalysts showed excellent photocatalytic activity compared with ZnO/C and pure ZnO, which is ascribed to the formation of ZnO–ZnS heterojunctions in catalysts. Furthermore, influences of preparation conditions on photocatalytic activity of the catalysts have been investigated.

Self-Assembled Fabrication of Superparamagnetic Highly Stable Mesoporous Amorphous Iron Oxides

In this article, we report the fabrication of highly stable amorphous mesoporous iron oxides (AMIOs) with surface tunable properties by a template-free method. AMIOs with surface areas from 264 to 43 m2/g and mesopore sizes from 5 to 11 nm were synthesized. The synthesized AMIOs were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectra, and nitrogen adsorption analysis. The XRD patterns indicated that the thermal decomposition of the ferric oxalate complex under open atmospheric conditions at low temperature (200−275 °C) and in inert atmospheric conditions at high temperature (400 °C) facilitates formation of crystallographically amorphous iron oxides. ζ-potential analyses of AMIOs indicated that they have almost similar points of zero charge. Magnetic measurements revealed superparamagnetic behavior, with magnetization values around 20 emu/g. The capacities of various amorphous iron oxides to remove As(V)...

Mechanistic Studies of CC Bond Cleavage of Nitriles by Dinuclear Metal Cryptates

We previously reported that dinuclear copper(II) cryptate [Cu(2)L](4+) cleaves the C-C bond of acetonitrile at room temperature to produce a cyano-bridged dinuclear cryptate and methanol, whereby the reaction mechanism has not yet become clear. We have now systemically investigated this reaction, and four cryptates, [Cu(2)L](ClO(4))(4) (1), [Zn(2)L](ClO(4))(4) (2), [Cu(2)L(H(2)O)(2)](CF(3)SO(3))(4) (5), and [Cu(2)L(OH)(OH(2))](ClO(4))(3) (6) are reported here. Cryptates 1 and 2 can cleave the C--C bonds of acetonitrile, propionitrile, and benzonitrile at room temperature under open atmospheric conditions to give cyano-bridged cryptates [Cu(2)L(CN)](ClO(4))(3) (3) and [Zn(2)L(CN)](ClO(4))(3) (4), respectively, and the corresponding alcohol. In contrast, 5 and 6 do not show any C-C bond activation of nitriles, as the interior axial positions of Cu(II) in 5 and 6 are occupied by water/OH(-). The C-C bond cleavage of (S)-(+)-2-methylbutyronitrile by 2 produced (R)-(-)-2-butanol only; that is, the cleavage reaction proceeds through an S(N)2 pathway (Walden inversion).

Mineralizer-Assisted Shape-Controlled Synthesis, Characterization, and Photocatalytic Evaluation of CdS Microcrystals

High-quality, well-crystallized, single-crystal, wurtzite CdS hexagonal microtowers (with and without tubular structure) and CdS with octahedral geometry were successfully synthesized by tuning the solvent ratio of water and ethanol for the first time on a large scale without using any catalysts or templates. The products were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry, transmission electron microscopy, and field emission scanning electron microscopy. CdS with microtowers, octahedral geometry, and hexagonal plates was formed by thermal decomposition of cadmium thiocyanate at 400 °C under open atmospheric conditions. The influence of solvent, initial precursor concentration, decomposition temperature, and time on the morphology of CdS was investigated, and the results were discussed. The XRD results showed that the cadmium thiocyanate complex is completely decomposed into CdS at 300 °C for 2 h and the wurtzite phase was formed under all experimental conditions, which opens a door for well-crystallized, single-phase CdS synthesis on a large scale. The diffuse reflectance spectra showed that CdS microtowers have strong visible light absorption compared with the octahedral geometry, revealing the existence of a profound shape−property relationship of CdS. The CdS microtowers with a Pt cocatalyst showed a high rate of photocatalytic hydrogen production from water containing 0.1 M Na2S and 0.1 M Na2SO3 as sacrificial reagents under visible light irradiation (λ ≥400 nm). The possible growing mechanism of various types of the CdS morphology was also discussed.

Synthesis of N, C Codoped Hierarchical Porous Microsphere ZnS As a Visible Light-Responsive Photocatalyst

A new N, C codoped visible light responsive hierarchical porous ZnS photocatalysts have been successfully synthesized by using a simple procedure in large scale without using catalyst or template. This is a first example of a nonmetal doped sulfide semiconductor photocatalyst working under visible light irradiation. N, C codoped ZnS catalysts were formed by thermal decomposition of zinc isothiocyanate at 300, 400, and 500 °C under open atmospheric conditions. The influences of various experimental conditions on the morphology of the catalysts have been investigated. The synthesized catalysts were characterized by the required analytical techniques. The N, C codoped catalysts possess well-crystallized wurtzite structure and have excellent visible light absorption when compared to undoped ZnS. Elemental and XPS analyses confirmed the presence of both nitrogen and carbon elements in ZnS. The chemical natures of nitrogen and carbon have been discussed on the basis of FTIR and XPS results. The visible light induced photocatalytic activity of these catalysts were investigated by using AO7 as a model pollutant and results showed that the synthesized catalysts have excellent photocatalytic activity. A possible growth mechanism of the hierarchical porous photocatalysts was proposed.

A Novel Micro Cooling System for Electronic Devices Using a Micro Capillary Groove Evaporator

In the presented study, a novel micro cooling system for electronic devices using a micro capillary groove evaporator was proposed. Based on experimental data in open (atmospheric) condition, we found that liquid level has an obvious influence on evaporating heat flux. For a given liquid level, there exists an optimum groove size, which maximizes evaporation heat transfer capacity. By using the optimum groove sizes in the open condition, two types of closed cooling systems for CPU chips for personal computers were designed: one was for desktop models and the other for notebook models. Their cooling performance to keep CPU chip temperature below 90degreesC reached 3.35 x 10(5)W/m(2) and 2.51 x 10(5)W/m(2), respectively, for the desktop model by using ethanol and the notebook model by using methanol. Experimental results show that the maximum cooling capacities strongly depend on the condensation capacities of condensers in the closed cooling systems and volume fractions of working liquid in the evaporators.

The influence of atmosphere on the formation behaviour of YBa2Cu3O7-x

The influence of reduced local partial pressure of CO2 due to virtually open atmosphere conditions on the sequence of reactions during the synthesis of YBa2Cu3O7-x from Y2O3, BaCO3 and CuO in air has been studied. Under these conditions, formation of (123) is observed to be complete within the first 30 min of calcination, through a reaction between intermediate phases Y2Cu2O5 and BaCuO2. Y2Cu2O5 also reacts with BaCO3, BaCuO2, and probably YBa2Cu3O7-x, individually to form Y2BaCuO5. The rapidly formed superconducting phase (123) is, however, unstable and decomposes into (211), BaO and CuO. BaO, thus released reacts with CO2 to form BaCO3. (211) reacts with other raw materials forming a stable (123) with (211) as the major impurity phase.