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Copper oxide (CuO) nanoparticles synthesized by green Synthesis method using Curcuma plant extract and Cu nitrate. This gives a large-scale production of CuO nanoparticles simply. X-ray diffraction pattern (XRD) reveals single-phase monoclinic structure. The transmission electron microscopy (TEM) showed 12–110 nm size of as prepared CuO nanoparticles. The optical properties the energy gap was 4.5 eV. The current voltage (I-V) test results showed that the solar cell's maximum power conversion efficiency (PCE) was 0.067%and the filling factor was 35%.

In this work, vanadium pentoxide (V2O5) thin films were prepared using rf magnetron sputtering on silicon wafer and glass substrates from V2O5 target at 200 °C substrate temperature, followed by annealing at 400 and 500 °C in air for 2 h. The prepared thin films were examined by X-ray diffraction (XRD), forier transform infra-red spectroscopy (FTIR), UV-visible absorbance, and direct current coductivity to study the effects of annealing temperature on their structural and optical properties. The XRD analysis exhibited that the annealing promoted the highly crystallized V2O5 phase that is highly orientated along the c direction. The crystalline size increased from 22.5 nm to 35.4 nm with increasing the annealing temperature to 500 °C. The FTIR spectroscopy showed the enhancement of the characteristics band for the V2O5 with increasing annealing temperature to 500 °C. The optical study showed that the energy gap for the sample deposited on glass slides decreased from 2.85 eV, for as deposited sample, to 2.6 eV upon annealing the sample to 500 °C. There was a linear dependence between sensitivity and relative humidity (RH) at the range from 25% to 70%, while the behavior was exponential at high RH range.

This study included a different weight ratio of copper (2, 4, 6, 8) wt% as a dopant, with tin oxide SnO 2 deposits on glass substrate by RF reactive magnetron sputter. The structural properties show polycrystalline pattern nature for all deposit samples with dominated reflection (110). The electrical conductivity increased to 1×130 10 S -1 and the optical conductivity to 35×10 16 S -1 . The energy gap decreased to 3.60 eV when the rate of deformation was 8wt%, due to the increase in the crystallite size to 24.5 nm with the improvement of crystallization. While the surface measurements showed an increase in the surface roughness to 50 nm when the rate of deformation at 8wt%.

This paper presents an experimental investigation of a new method of phase change materials (PCMs) integration in one or both the evacuated tube (ET) and two separated tanks adjacent to the water tank of heat pipe evacuated tube solar water heater collector (HP/ETC). In this method, the evacuated tube was filled with medical paraffin wax as thermal heat storage, while the two separated tanks were filled with paraffin wax (grade-A). Therefore, owing to the thermal isolation of the evacuated tube and PCM storage tanks, heat is efficiently accumulated and stored for a longer time. The advantage of this new method is that improved overall solar water heater performance by delayed heat release, thereby supplying hot water for a long time at high demand or when low solar intensity. Four HP/ETSCs with gravity assist heat pipe (GAHP) rigs were used for a comparative study. The first HP/ETC was equipped with PCM in its ET and two PCM storage tanks. The second and third HP/ETCs were integrated with PCM in an ET and two PCM storage tanks, respectively. While the fourth HP/ETC was considered a reference as it was left without PCM. Each heat pipe was filled with a 0.7 filling ratio of pure acetone. The tests are carried out with two different rates of water flow (i.e. 1 and 2L/h). The results demonstrate that the integration of PCM in both the ET and the separated tanks gives an efficiency improvement of 55.7%, While the integration of PCM in the ET led to an increase in the efficiency of 49.9%. Whereas the efficiency has been improved with the integration of PCM in the separated tanks by about 36.5%, compared with PCM-free reference collector.

The conventional solid-state reaction method was utilized to prepare a series of superconducting samples of the nominal composition Bi2-xPb0.3WxSr2Ca2Cu3O10+d with 0≤x≤0.5 of 50 nm particle size of tungsten sintered at 8500C for 140h in air . The influence of substitution with W NPs at bismuth (Bi) sites was characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and dc electrical resistivity. Room temperature X-ray diffraction analysis revealed that there exists two phases, i.e. Bi-(2223) and Bi-(2212), in addition to the impurity phases of (SrCa) 2Cu2O3, Sr2Ca2Cu7Oδ, Ca2PbO4, CaO, and WO. It was found that the crystallographic structure of all samples was orthorhombic. Lattice parameter values and the volume fraction of the (2223)-phase of the prepared samples were also calculated. The superconductivity transition temperature (Tc) for samples subjected to substitution with W NPs was found to be higher than that for the pure sample. The optimal value of W NPs content in (Bi, Pb)-2223 system was found to be at x=0.3.

Material selection is one of the vital and critical steps in the mechanical design process. In recent times, various tools based on the multi-criteria decision-making process are used successfully to cope with such complexity in material selection. .This work provides appropriate methods and tools to find the optimum thermoplastic polymer reinforced natural fiber composites. The material selection applied using a decision-making model that consists of the „Technique for Order of Preference by Similarity to Ideal Solution“ (TOPSIS) and „Vlsekriterijumska Optimizacija I Kompromisno Resenje“ (VIKOR) methods in order to rank of the materials according to applied criteria. Analytical Hierarchy Process (AHP) method was performed in order to determine the weighting of the material properties or criteria. Rank the materials were gained by using ranking scores as results of the methods use. The results offer that the best polymers were found to be the LDPE and Nylon 6,6. It was proved that the multi-criteria decision-making model is an application for solving complex material choice decision problems. This model can be applied to other engineering applications with any number of alternatives and criteria for material selection.

There are many reasons neededfor continuous evolution in concrete technology; one of them concern on the greenhouse gas emission and depletion of natural resource as a results of high production of Portland cement. Many solutions are used to solve these problems; one of them is using cement replacement materials in concrete like metakaolin (in micro or Nano scale) which offered positive effect on the properties of cement concrete. Therefore, the main aim of this study is to evaluate and compare the effects of metakaolin (MK) and Nano-metakaolin (NMK) on some physical and mechanical properties of cement mortar. For this purpose, mortar mixes are prepared by substituting cement (by weight) with (10%) metakaolin or (1, 3, 5, and 7%) Nano - metakaolin. The amount of binder for mortar mixtures is 700 kg/m with a constant water / binder ratio of 0.33. Workability, apparent density, water absorption, compressive strength, and flexural strength of all mortar mixes are determined and compared with reference mix without any mineral admixture (0% MK or NMK). The results indicated that the performance of mortar mixes can be enhanced by metakaoline replacement. Furthermore, Nano-metakaolin has significantly positive impacts on the properties of mortar mixes which have found to be improved with increasing the Nano-metakaolin replacement, due to better pore refinement, micro filling action, and higher pozzolanic reaction. The optimum Nano-metakaolin substitution ratio (7%) causes increase in compressive and flexural strength reach to (82.6% and 59.5%), respectively compared with the reference mix, at age of 28 days.

This work is related to the investigation of the effects of porous silicon (PSi) morphologies on the performance of plasmonic gold nanoparticles (Au-NPs) hot spot SERS sensors for the detection of amoxicillin molecules. Two Si wafers with different resistivity values of 10 and 100 Ω.cm were used to synthesize a PSi layer of pores- and mud-like structures, respectively, by pulsed photo chemical etching process. The hot spot SERS sensors were synthesized by incorporating the Au-NPs within the PSi morphologies of pores- and mud- like structures which are characterized by high density of nucleation sites. Plasmonic Au- NPs with different sizes and hot spot regions were incorporated into the porous structures by the ion reduction process. It was recognized that the PSi morphologies have a considerable influence on the fabrication process of the detection sensors and, consequently, on the detection process. The plasmonic Au-NPs hot spot SERS sensor based on the PSi morphology of the mud-like structures shows higher sensitivity than that of pores-like structures, even at very low concentrations of amoxicillin solutions.

Recent studies have indicated that that the application of nickel oxide (NiO) regulator nano-films is growing. The sol-gel method has become the primary method for preparing NiO thin films. This paper describes a method to achieve optimum NiO thin films through this method. Nanostructured NiO nanoparticle (NP) films were successfully fabricated using the sol-gel method at different annealing temperatures as a photosensor device. This was carried out using a systematic change of parameters, such as the thermal annealing, to study the effect on the size of the metal oxide nanoparticles. The optical, structural and electrical properties of NiO nanoparticle films were characterised by ultraviolet-visible (UV-visible) and X-ray diffraction analyses. The results show that the films exhibit an average grain size depending on the annealing temperature. The optical properties revealed that the deposited films were p-type, and increasing the annealing temperatures leads to a shift in the maximum value of the absorption peak towards long wavelengths (red). This results in a drop in the energy gap as the annealing temperature increases. The voltage-current characteristics for both types of NiO/p-Si heterojunction (dark and illuminated) were investigated as a function of the annealing temperature. This study demonstrated that the best-estimated structural, optical, and electrical characterisations were achieved with NiO films at 650 °C.

This paper presents an experimental assessment of the repair effectiveness of Carbon Fibre Reinforced Polymer (CFRP) laminate for damaged Reinforced Concrete (RC) beams with a circular web opening at the shear zones. The study highlights the effect of the opening diameter on CFRP repair effectiveness by examining the effect on the ultimate load capacity, deflection, steel strain, CFRP laminate strain and failure modes. In the experimental programme, a total of four beams were used inclusive of one solid beam used as a control beam. The other three beams were designed with different opening diameters and were exposed to damage at the pre-repair stage, up to their ultimate capacity. Damaged beams were repaired using externally bonded CFRP laminate around the openings. The results concluded that the CFRP laminate repair system was effective regardless of the web opening diameter. It was found that the increase in the opening diameter resulted in a higher deflection as well as higher strain values for the mid-span reinforcement and shear stirrups. The CFRP repaired beams behaviour transformed from brittle at the pre-repair stage to ductile at the post-repair stage. The failure mode of the CFRP repaired beams with a smaller opening diameter changed from shear failure to flexural failure, while the larger opening diameter beams failure mode was governed by CFRP deboning at the shear zone.

Polyacrylonitrile carbon fibre is one of the fibres that can be used in civil engineering applications. It is also called carbon graphite and graphite fibre. These types of fibre contain a large number of carbon filament sets. The objective of this study is to investigate the effect of carbon fibre on the resistance of concrete to fires that could occur in concrete structural elements. This study used two percentages of carbon fibre that were added to concrete mixes using 1% and 2% of cement. Three mixes were made: normal concrete (NC), 1% carbon fibre concrete (1% CFC) and 2% carbon fibre concrete (2% CFC). Six tests were conducted to evaluate the performance of the concrete mixes: the slump test, the compressive strength test (before and after exposure to fire), the flexural strength test, the thermal conductivity test and the rebound hammer test. The test results showed that 1% CFC exhibited higher compressive strength when subjected to fire and high temperatures compared to the other mixes. Moreover, the addition of 2% of carbon fibre reduced the compressive strength to an even lower level than that of the normal concrete mix.

Carbon dots (CDots) are defined as surface-passivated small carbon nanoparticles, with the effective passivation generally achieved by organic functionalization. Photoexcited CDots are both potent electron donors and acceptors, and their characteristic bright and colorful fluorescence emissions make them excellent fluorescence sensors for organic analytes and metal ions. For the latter extraordinarily low detection limits based on extremely efficient quenching of fluorescence intensities by the targeted metal cations have been observed and reported in the literature. However, all of the dot samples in those reported studies were made from “one-pot” carbonization of organic precursors mostly under rather mild processing conditions, unlikely to be sufficient for the required level of carbonization. Those dot samples should therefore be more appropriately considered as “nano-carbon/organic hybrids”, characterized structurally as being highly porous and spongy, which must be playing a dominating role in the reported sensing results. In this study, we compared the dot samples from carbonization syntheses under similarly mild and also more aggressive processing conditions with the classically defined and structured CDots for the fluorescence sensing of copper(II) cations in aqueous solutions. The observed dramatic decoupling between quenching results for fluorescence intensities and lifetimes of the carbonization samples, with the former being extraordinary and the latter within the diffusion controlled limit, suggested that the quenching of fluorescence intensities was greatly affected by the higher local quencher concentrations than the bulk associated with the porous and spongy sample structures, especially for the sample from carbonization under too mild processing conditions. The major differences between the classical CDots and the nano-carbon/organic hybrids are highlighted, and the tradeoffs between sensitivity and accuracy or reproducibility in the use of the latter for fluorescence sensing are discussed.

This study investigates how microstructure and chemistry effects by Nano-Metal-Phosphate and the kinetics of growth passive layer and passivity breakdown. Additionally, the passive layer germination behavior on aluminum alloy 1050 with anticorrosive properties. The passive layer is an alloying method which allows an aluminum oxide to germinate. Morphologically and structurally, the aluminum oxide films were characterized using microscopy analyzes and XRD analysis. Results indicated that the reinforcements are well distributed and the grin size is downy. Corrosion behavior tested by Cyclic polarization exam and done at room temperature in (3.5 per cent NaCl) solution. The reinforcement increased the hardness for processed aluminum from Hv81.1 to HV=120.492 as castings. The parameter Nano-Metal-Phosphate has attenuated the current density of corrosion (7.15μA / cm2) compared to the as-cast sample results.

Li-rich layer-structured cathode thin films have been successfully synthesized by combustion technique and deposited by Pulsed Laser Deposition (PLD) technique to produce LCNAO Ferrimagnetism. Pulsed Nd-YAG laser with wavelength ( λ = 532 nm ) was used and for (10 ns) and energy influence (1.4 J/cm2) at different substrate temperatures (100, 200, 300) °C and O2 pressure at 10 mbar. The structure, morphology, and magnetic properties of the films were determined by XRD, FESEM, SEM, and VSM. The results, Li rich layered structure at peak (003), very smooth surface without any pinholes or cracks. The film’s cross-section view on the Si substrate was used to estimate the film thickness, which was about 63.83 nm. Better crystalline features and spherical shape, average particle size of (1-12) nm could be obtained at substrate temperature of 200 °C. The result obtained at Ms (0.695) emug-1 of powder larger than LCNAO thin film (0.147) emug-1 about 5 times with natural soft loop has emerged with a very small coercive field. The equivalent circuits of the thin film was determined by EIS at substrate temperature (100) °C,with double layer capacitance, high surface area and indicated configuration of equivalent circuits and their symbols (CR(CR)(CR)(CR)) with no defects. Finally, a LiCo0.5Ni0.45Ag0.05O2 promising cathode material for LIBs because of the high theoretical capacity of 1068.5 mAhg-1. This encourages use as a small, easy-to-carry, high storage capacity in lithium batteries - Ion battery charger used in microelectronics, magnetic resonance devices, or future Electric Vehicles (EVs).

Water-resistant surfaces are very important to many modern technology applications. So the progresses of hydrophobic & hydrophilic surfaces for self-cleaning applications has received widespread attention over the past years. In this paper, investigating in self-cleaning surfaces technique are presented. Nickel oxide Nanoparticles (NiONPs) were manufactured at different concentrations on the porous silicon (PSi) surface by immersion plating process, which filled with square-pores like structure which affected in classification of hydrophilic and hydrophobic surfaces. This green method to prepare Nickel oxide Nanoparticles/porous silicon (NiONPs/PSi) structures was interesting because it is effective for self-cleaning applications and is low cost and environmentally friendly. NiONPs/PSi structures characterized by the use of X-Ray Diffraction, electron microscopy scanning, Fourier-transform infrared (FTIR) analysis, Ultraviolet–visible (UV) spectroscopy, and contact angle analysis. The results show that hydrophilicity & hydrophobicity of these structures strongly depend on the surface morphology of porous silicon and the resulting the shape and distribution of NiO nanoparticles. From all results, it was found that the optimum contact angle is 118° at a NiO concentration of 10-2 M for the NiONPs/PSi structure which has hydrophobic properties as it can be used as a self-cleaning surface.

The present work is an experimental investigation of heat and mass transfer with frost growth over flat plate surface. This study focuses on the most important factors affecting the frost formation process, i.e. the surrounding air temperature, air humidity and air velocity, and the plate surface temperature. Experiments were carried out using a purpose-built apparatus to acquire data to measure the thickness of frost layer, and surface temperature of frost layer. Results showed that the plate surface temperature and air velocity have the greatest effect on frost layer thickness and heat and mass transfer coefficients, relative to the air humidity and air temperature. Comparisons between present exponential results and previous work relevant to this study show a fairly good agreement.

Drawing blood and injecting drugs are common medical procedures, for which accurate identification of veins is needed to avoid causing unnecessary pain. In this paper, we propose a low-cost system for the detection of veins. The system emits near-infrared radiation from four light-emitting diodes (LEDs), with a charge-coupled device (CCD) camera located in the middle of the LEDs. The camera captures an image of the palm of the hand. A series of digital image-processing techniques, ranging from image enhancement and increased contrast to isolation using a threshold limit based on statistical properties, are applied to effectively isolate the veins from the rest of the image.

In the current study, the Si nano column layer via pulsed photo chemical etching with different laser pulse duty cycle 30 and 60% using short laser wavelength (405 nm) and laser intensity (100 mW/cm2) was formed and studied. Two types of Si nano column-based plasmonic Au-NP hot spot layers were synthesized and examined successfully as an efficient SERS layer for the detection of the ultra-low concentration of amoxicillin. Si nano columns exposed a great effect on the performance of the Au-NP hot spot SERS sensor showing a strong dependence on the density of the hot spot gaps within the sensitive layer. Enhancement factor (EF) of the Raman signal improved considerably with increasing the density of the hot spot gaps due to the coupling efficiency among the plasmonic Au-NPs and the molecules of amoxicillin within the hot spot regions. EF increased by about four orders of magnitude with decreasing the laser duty cycles due to the increase of the integrated plasmonic Au-NPs into the Si nano column layer.

In this effort, the tribological behavior of epoxy resin filled with treated ceramic carbides fillers has been investigated. The epoxy matrix composite was prepared with different weight fraction (0, 5, 10 and 15%) separately for both silicon and boron carbides ceramic particles using hand-lay methodology. The wear characteristics represented by weight loss and coefficient of friction at different average load (30, 40, 50 N) with two sliding velocity (2.5, 5 m/s) and constant sliding distance. It was noticed from the acquired results, there is obvious improved in the wear behavior of epoxy resin when filled with treated ceramic carbide particles (especially boron carbides) related to unfilled epoxy resin and theses enhancement increased with increasing the weight fraction of fillers.

In this study, we report the synthesis of a fumed silica supported Ni-based catalyst for carbon dioxide conversion to methane. Ni/fumed-SiO2 was prepared by loading the active agent precursor solution on the high surface area fumed SiO2 through the wet impregnation technique. Thereafter, the resulting powder was dried and reduced under hydrogen flow at 750°C for 3 h to get the desired active agent. The CO2 catalytic hydrogenation was performed using a flow reactor between 50 and 650°C temperature, where it showed good catalytic activity and selectivity for methane. In addition, it is found to be highly stable under reaction conditions for 16 h time on stream. Fresh and used (after the stability test) catalyst samples were characterized using different techniques, such as XRD, TEM, SEM/EDX, to investigate the structural and morphological properties, and effect of exposure to reaction conditions on the catalysts. Furthermore, the reaction mechanism was investigated using in-situ DRIFT in the temperature range 50–450°C. The results revealed the formation of formate species at early reaction stages, followed by CO that was detected as linearly adsorbed on Ni surface, and lastly methane formation. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd. This publication was made possible by NPRP grant (NPRP8-509-2-209) from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors also gratefully acknowledge the Center for Advanced Materials (CAM) at Qatar University for services related to XRD analysis. The SEM and TEM analysis were accomplished in the Central Laboratory Unit, Qatar University and the authors greatly appreciate their assistance in the characterization of the samples. Scopus

Development of a highly efficient and coke-resistant, nickel based nano-catalyst in the carbon dioxide reformation of methane is reported. The alumina supported Ni-based catalyst with a metal loading of 5wt% was prepared via the solution combustion synthesis (SCS) method as well as the conventional wetness impregnation method. The synthesized catalysts were thoroughly characterized by a combination of analytical techniques including high-resolution electron microscopy (HRTEM-SAED), X-ray diffraction (XRD), nitrogen physisorption (BET surface area), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (H 2 -TPR) and temperature programmed oxidation (TPO). Compared to the conventional nickel-impregnated (Ni-I) catalyst, the Ni-SCS nano-catalyst was superior in activity and stability during dry reformation of methane. Ni-SCS catalyst exhibited higher percentage conversions of methane and carbon dioxide. The percentage yields of hydrogen and carbon monoxide over Ni-SCS catalyst were also significantly higher. During the investigated period on stream for 50 h, the Ni-I catalyst deactivated severely, by contrast the Ni-SCS stayed active. It was clear from the results of elemental carbon analysis and TPO that deactivation of the Ni-I catalyst was due to severe carbon deposition, whereas the Ni-SCS catalyst exhibited minor carbon deposition. These differences in the catalytic activities and stabilities between the Ni-I and Ni-SCS catalysts were attributed to the difference in their physicochemical properties and chemical structure, as obvious from the results of the above mentioned analysis techniques. The XRD and XPS analysis revealed that the Ni-SCS nanocatalyst resulted in the formation of uniformly distributed nickel aluminates (NiAl 2 O 4 ) nano-crystallite spinels together with nickel oxide. The results of H 2 - TPR analysis clearly distinguished between NiO and NiAl 2 O 4 . H 2 -TPR affirmed the formation of NiAl 2 O 4 and NiO species on the SCS nanocatalyst but only NiO within the impregnation catalyst. In this regards the exceptionally high catalytic activity and stability of Ni-SCS nanocatalyst during dry reformation was attributed to the presence of NiAl 2 O 4 nano-crystallites structures. On the other hand, the presence of weakly associated NiO species on the Ni-I catalyst was responsible for decaying its activity due to carbon formation during the dry reformation of methane. This research work was made possible by the Qatar Shell Research and Technology Center (QSRTC) funded project QUEX-CENG-QSRTC-18/19 . Scopus

The effect of using basalt fibers in the matrix of ultra-high performance concrete (UHPC) T-beam on the diagonal crack-load and ultimate shear capacity was investigated experimentally. The results compared to similar T-beam containing steel fibers in equal percent. The beam was reinforced with longitudinal bars but did not have transverse shear reinforcements. Two parameters were adopted in this study. These were the volume fraction of fibers and the shear span to effective depth ratio. The results showed that using steel fibers in the matrix led to a ductile behavior upon failure more than adding basalt fibers. Adding basalt fibers to UHPC enhances compressive strength more than the addition of steel fibers at equal percent. The enhancement was reflected in the shear capacity of the compression zone of the T-beam. Also, the compression zone in the T-beam was enlarged due to the presence of the flange. Therefore, the flange contributed to raising the compression shear capacity. Incorporating basalt fibers in the matrix of UHPC delayed the initiation of diagonal cracking more than steel fibers did. Adding basalt fibers at 0.5%, 1.0%, and 1.5% raised the cracking shear load by 160% over the non-fibrous one. However, the 0.5% and 1.0% basalt fibers upheaved the ultimate shear capacity more than the 1.5% content. The 1.5% steel fiber content promoted the shear capacity by 133% over the non-fibrous one. Also, the shear span to effective depth (a/d) ratio had a significant effect on the shear capacity of the beam. Increasing the a/d ratio led to decreasing the shear capacity and raising the mid-span deflection of the T-beam. However, the recorded deflection of the UHPC T-beam was low compared to the conventional concrete one.

Hexagonal boron nitride (h-BN) and exfoliated nanosheets (BNNs) not only resemble their carbon counterparts graphite and graphene nanosheets in structural configurations and many excellent materials characteristics, especially the ultra-high thermal conductivity, but also offer other unique properties such as being electrically insulating and extreme chemical stability and oxidation resistance even at elevated temperatures. In fact, BNNs as a special class of 2-D nanomaterials have been widely pursued for technological applications that are beyond the reach of their carbon counterparts. Highlighted in this article are significant recent advances in the development of more effective and efficient exfoliation techniques for high-quality BNNs, the understanding of their characteristic properties, and the use of BNNs in polymeric nanocomposites for thermally conductive yet electrically insulating materials and systems. Major challenges and opportunities for further advances in the relevant research field are also discussed.

This paper presents an experimental investigation to verify the thermal performance of a window-type air-conditioning system equipped with an innovative type of heat-pipe heat exchanger (HPHE). As the use of this type of heat exchanger leads to a reduction in the power consumed by the compressor. So, there is an increase in the coefficient of performance (COP) of the system which is the main measure for the efficiency of the air conditioning system. In this study, distilled water, acetone, and R-134a were selected as working fluids to fill the proposed HPHE with two various filling ratios (FR = 50% and 100%) to do the experimental investigation. The results indicated that equipping the system with the proposed type of heat exchanger gives a saving in the consumed power with (2.01, 2.195, and 1.33%) for 100% filling ratio of water, acetone, and R-134a as working fluids, respectively, compared to the regular system not equipped with the heat exchanger. Also, the results show that using innovative HPHE in the AC system led to an enhancement of refrigeration effect by about (3.5, 6.03, and 3.97%) at R134a, acetone, and water working fluids, respectively with (F.R = 100%)

The microstructure, physical, dielectric and the piezoelectric characteristics of the (K0.5Na0.5) (Nb0.9Ta0.1) O3 (KNNT) ceramics as a function of the sintering temperature and Nd2O3 dopant were inspected in this work. It was found that the sintering temperature has a significant impact on the above-mentioned properties. In the same context, the addition of HYPERLINK "https://pubchem.ncbi.nlm.nih.gov/compound/Neodymium_oxide" neodymium oxide led to remarkable improvement in the microstructure, density, dielectric and piezoelectric properties of KNNT ceramics when compared to undoped ceramics.

The absorption spectra of five Fe(II) homoleptic and heteroleptic complexes containing strong sigma-donating N-heterocyclic carbene (NHC) and polypyridyl ligands have been theoretically characterized using a tuned range-separation functional.From a benchmark comparison of the obtained results against other functionals and a multiconfigurational reference, it is concluded that none of the methods is completely satisfactory to describe the absorption spectra.Using a compromised choice of 20\% exact exchange, the electronic excited states underlying the absorption spectra are analyzed.The low-lying energy band of all the compounds shows predominant metal-to-ligand charge transfer (MLCT) character while the triplet excited states have metal-centered (MC) nature, which becomes more pronounced with increasing the number of NHC-donor groups. Excited MC states with partial charge transfer to the NHC-donor groups are higher in energy than comparable states without these contributions. The presence of the low-lying MC states prevents the formation of long-lived MLCT states.

This study was involving the dispersion method of nano-materials replacement and the interaction with cement mortar behavior for many mortar samples under variable curing time ,with constant water to cement ratio (W/C=0.45) .Some mechanical properties such as (compressive, flexural strength and hardness tests) was studied. The main parameters are depending on the small amount replacement ratio of nano-particle (ZrO2) with respect to the mass of the cement (OPC) type (I). The addition of nano-material by replacement on the mixture of mortar includes (1, 2, 3,4and 5%) with constant W/C ratio and also the amount of the fine aggregate use is 2.75 from the amount of cement. The results show that, the strength of the mortar that consist from colloidal nano materials give better properties than from both mortar with dry nano-materials replacement and without nano-materials in all test, But the nano-Zirconia materials give good properties up to 2% in all tests compared with control cement mortar.

Boron nitride nanosheets (BNNs) are pursued for their high thermal conductivity yet electrical insulation and their extreme thermal and chemical stabilities for a variety of applications. For high-quality BNNs, a number of exfoliation approaches under different processing conditions were evaluated. Three more effective methods were identified, including method-A based on refluxing and vigorous sonication in isopropyl alcohol, method-B involving ball-milling in urea, and method-C with the aid of ammonia in hydrothermal processing. These methods produced BNNs of apparently different structural and morphological characteristics, with those from the first two being smaller pieces, more defective, and their polymeric nanocomposites exhibiting relatively lower thermal conductive performance. The method-C yielded BNNs of obviously better quality, as also made evident by the observed high thermal diffusivities of their corresponding polymeric nanocomposites. Correlations of exfoliation approaches and conditions w...

In this work, synthesis of nickel oxide (NiO) using nickel acetate as a starting material by sol–gel method and then deposited as collide on glass slides to form thin layers of NiO by spin-coating technique with high photo-catalytic activity using as self cleaning coating. These films of NiO were annealed at different temperature 450 °C, 550 °C. The structural, morphological, spectral and optical properties of prepared NiO thin films were measured by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Ultraviolet spectroscopy (UV-visible) respectively. These results; it was shown that the crystallinity of NiO films evolves gradually as the temperature of the annealing films increases. Depended on the (SEM) and (AFM) result in the average grain size is a range of (15–30) nm. The films achieved a higher optical transparency of thin films synthesis it was annealing at 550 °C temperature. Finally, photo-catalytic test were studies by using potassium permanganate (KMnO4) as a model of pollutant with two methods for achieved the effect of annealing temperature of NiO thin films on the photo-catalytic test and effect the grain size and weight of NiO nanopowder for photo-degradation percentage under exposure to UV-Visible source irradiation. Keywords: Nickel oxide (NiO), Sol gel processing, Contact angle, SEM, XRD, AFM

Proton exchange membrane fuel cell (PEM-FC) aggregation pressure causes extensive strains in cell segments. The compression of each segment takes place through the cell modeling method. In addition, a very heterogeneous compressive load is produced because of the recurrent channel rib design of the dipole plates, so that while high strains are provided below the rib, the domain continues in its initial uncompressed case under the ducts approximate to it. This leads to significant spatial variations in thermal and electrical connections and contact resistances (both in rib–GDL and membrane–GDL interfaces). Variations in heat, charge, and mass transfer rates within the GDL can affect the performance of the fuel cell (FC) and its lifetime. In this paper, two scenarios are considered to verify the performance and lifetime of the PEM-FC using different innovative channel geometries. The first scenario is conducted by adopting a constant channel height (H = 1 mm) for all the differently shaped channels studied. In contrast, the second scenario is conducted by taking a constant channel cross-sectional area (A = 1 mm2) for all the studied channels. Therefore, a computational fluid dynamics model (CFD) for a PEM fuel cell is formed through the assembly of FC to simulate the pressure variations inside it. The simulation results showed that a triangular cross-section channel provided the uniformity of the pressure distribution, with lower deformations and lower mechanical stresses. The analysis helped gain insights into the physical mechanisms that lead to the FC’s durability and identify important parameters under different conditions. The model shows that it can assume the intracellular pressure configuration toward durability and appearance containing limited experimental data. The results also proved that the better cell voltage occurs in the case of the rectangular channel cross-section, and therefore, higher power from the FC, although its durability is much lower compared to the durability of the triangular channel. The results also showed that the rectangular channel cross-section gave higher cell voltages, and therefore, higher power (0.63 W) from the fuel cell, although its durability is much lower compared to the durability of the triangular channel. Therefore, the triangular channel gives better performance compared to other innovative channels.

A range of Pt:Cu bimetallic nanoparticles were investigated for the liquid-phase selective hydrogenation of furfural, an important platform biomass feedstock. Alloying of the two metals had a profound effect on the overall catalytic activity, providing superior rates of reaction and achieving the needed high selectivity towards furfuryl alcohol. Furthermore, we investigated the catalytic activity of an Ultra Dilute Alloy (UDA) formed via the galvanic replacement of Cu atoms by Pt atoms on dispersed host Cu nanoparticles (atomic ratio Pt:Cu 1:20). This UDA, after overcoming an induction period, exhibits exceptionally high initial rates of hydrogenation under modest hydrogen pressures of 10 and 20 bar, rivalling the catalytic turnover for the monometallic Pt (containing 12 times more Pt), and outdoing the pure Cu or other compositions of bimetallic nanoparticle alloy catalysts. These atom efficient catalysts are ideal candidates for the valorization of furfural due to their activity and vastly greater economic viability.

Carbon dots were originally found and reported as surface-passivated small carbon nanoparticles, where the effective surface passivation was the chemical functionalization of the carbon nanoparticles with organic molecules. Understandably, the very broad optical absorptions of carbon dots are largely the same as those intrinsic to the carbon nanoparticles, characterized by progressively decreasing absorptivities from shorter to longer wavelengths. Thus, carbon dots are generally weak absorbers in the red/near-IR and correspondingly weak emitters with low quantum yields. Much effort has been made on enhancing the optical performance of carbon dots in the red/near-IR, but without meaningful success due to the fact that optical absorptivities defined by Mother Nature are in general rather inert to any induced alterations. Nevertheless, there were shockingly casual claims in the literature on the major success in dramatically altering the optical absorption profiles of “carbon dots” by simply manipulating the dot synthesis to produce samples of some prominent optical absorption bands in the red/near-IR. Such claims have found warm receptions in the research field with a desperate need for carbon dots of the same optical performance in the red/near-IR as that in the green and blue. However, by looking closely at the initially reported synthesis and all its copies in subsequent investigations on the “red/near-IR carbon dots”, one would find that the “success” of the synthesis by thermal or hydrothermal carbonization processing requires specific precursor mixtures of citric acid with formamide or urea. In the study reported here, the systematic investigation included precursor mixtures of citric acid with not only formamide or urea but also their partially methylated or permethylated derivatives for the carbonization processing under conditions similar to and beyond those commonly used and reported in the literature. Collectively all of the results are consistent only with the conclusion that the origins of the observed red/near-IR optical absorptions in samples from some of the precursor mixtures must be molecular chromophores from thermally induced chemical reactions, nothing to do with any nanoscale carbon entities produced by carbonization.

In this work, the interaction of methane and carbon dioxide on α-quartz with surface 001, with a siloxane termination (dense) surface was investigated by means of Ab-Initio Molecular Dynamics. Different temperatures were addressed, ranging from 298 to 423 K. For completeness, pure and mixed compositions were considered, to replicate the conditions present during Enhanced Gas Recovery processes by CO2 injection. When considering pure compositions, both gases stick to the surface, except for the highest temperature (423 K), where most of CH4 tend to desorb. When mixed compositions are addressed, carbon dioxide generally hinders the interaction of methane, except for high temperature, where both gases are equally distributed both close and far from the surface. To the goal of improving EGR processes on sandstone reservoirs, this work shows that a temperature of 323 K offers the best efficiency by increasing the interaction of carbon dioxide and pushing methane out of the surface. At the same time, this study would not recommend the use of very high temperatures (T > 373 K) and excessive concentration of CO2, as the majority of this gas would desorb, without improving methane extraction in a meaningful way. The authors would like to acknowledge the support of Qatar National Research Fund (a member of Qatar Foundation) through Grant # NPRP10-0125-170235 . The findings achieved herein are solely the responsibility of the authors. The authors would like to thank Texas A&M University in Qatar for the use of their computational resources. Scopus

The increasing demand for pure tungsten and its compounds due to their high tensile strength makes them a versatile material in catalyst, heavy alloy, cemented carbide, among others. This exceptional property makes it to be of high interest by industrialists for use in the engineering and manufacturing industries. Thus, preparation of ammonium metatungstate (AMT) from a Nigerian wolframite ore by hydrometallurgical technique was examined in sulphuric and phosphoric acid. During leaching, parameters such as leachant concentration, reaction temperature, and particle size on ore dissolution were examined. At optimal conditions (2.0M H2SO4 + 0.15M H3PO4, 75 °C, −63 µm), 93.7% of the ore dissolved within 120 min. The calculated activation energy of 6.93 kJ/mol supported the proposed diffusion mechanism. The leachate at optimal conditions was treated to obtain a pure tungstate solution. The purified solution was beneficiated to prepare a high grade AMT ((NH4)6[H2W12O40]·4H2O: 96-901-3322, m.p.: 98.7 °C, density: 2.16 g/cm3), which serves as an intermediate for some defined industries.

In the present work, Li MO2 (Li CoO2, Li NiO2, LiMnO2, or LiFeO2) metal oxides of the transition lithium layers were modified to serve as cathode materials for lithium-ion batteries, usually prepared by combustion reaction for better electrochemical efficiency. Li: Co: Ni: Fe: O2 (LCNFO) powder was first prepared in a weight percentages mixture of 1:0.5:0.45:0.5:1 with citric acid as fuel, and de-ionized water DIW as a binding material, and then mixed with nitrate of lithium ion (Li+) and a Fe+3 to obtain a regular blend. With some addition of citric acid and de-ionized water, a powder was obtained, which then heated up to 900 °C for 8 h. Several investigations were carried out to examine the powder properties in order to adopt it for thermal and thermo-gravimetric analysis applications. The microstructure of the powder was investigated using X-ray diffraction (XRD) analysis. A well-selected annealing temperature can produce a pure single-phase LCNFO material with good electrochemical behavior. The particle size of the LCNFO material had been approximately measured from the XRD outcome, utilizing Scherer formula. The electrochemical properties of the LCNFO layers were studied, and surface topography of LCNFO powder was examined utilizing Atomic force microscopy AFM. The results show an enhancement in the properties of the LCNFO cathode material prepared by a combustion reaction in the air, which has a larger storage capacity, and thus, it considers a promising alternative to other LiCoO2, LiNiO2, and LiMnO2 cathode materials. This preparation method is simple and effective to produce such nanostructures layers with high quality and cost-effectiveness for portable batteries application.

In this work, manufacture of Nickel Oxide nano-particles (NiONP’s) using sol-gel spin-coating method and deposited onto glass substrates as thin films. Nickel acetate was used as a starting material and annealed at different temperature (450°C, 550°C and 650°C).The structural, morphological, spectral and optical properties of synthesized NiONP’s were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Ultraviolet spectroscopy (UV-visible) respectively. Of the results, it was found that the crystallization of films develops strongly as the temperature of the annealing increases. Average particles size are range (15-30) nm. The thin films showed a higher optical transparency of thin films prepared at the beast annealing temperature 650C. Finally, Self-cleaning test were studies with and without UV lamp through important test hydrophicilty by measuring the Water Contact Angle results showed super-hydrophobicity properties

High-quality boron nitride nanosheets (BNNs) characterized by large aspect ratios and less defective surfaces and structures are in demand for thermal management and other uses that exploit the uniquely advantageous properties of boron nitride, such as being highly thermally conductive yet electrically insulating and extreme chemical and thermal stabilities. In this study, an ammonia-assisted exfoliation processing method was developed and applied to the preparation of high-quality BNNs. As a demonstration of the excellent potential of these nanomaterials, the BNNs were dispersed in polyethylene polymers for nanocomposite films of superior thermal transport performance at levels significantly beyond the state of the art in the literature. Effects of crosslinking in the nanocomposite film structure on thermal transport were also explored and favorable outcomes were achieved.

This paper evaluates the γ-radiation shielding traits of some new types of borate glasses of composition (70–x)B2O3–10Bi2O3–10BaO–10CdO–xPbO (where 0 ≤ x ≤ 20 mol%) prepared using melt quenching method. As-quenched samples were characterized to determine the effects of various PbO contents on their γ-radiation shielding properties. XRD patterns of the samples verified their amorphous nature. The Phy-X and XCOM was used to compute the mass attenuation coefficients of the glasses and then compared with the experimental data. The γ-radiation shielding performance of the proposed glasses were evaluated in terms of diverse attenuation parameters like mean free path, half and tenth value layer, atomic cross-section, electronic cross-section, effective atomic number and effective electron density. The γ-radiation shielding performance of the glasses were significantly improved with the increase of PbO contents. This new borate glass system is established to be advantageous for the radiation shielding applications.

This study involves natural--materials replacement and its reaction with cement mortar behavior for many mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5).In this researchsomeproperties such as (compressive strength the surface hardness and water absorption test), were affected by adding small ratios ofpowder (from (RHA) and (BRP) particles)as replacements to the Ordinary Portland Cement (OPC) / type (I). The percentages of natural materials additives replacement on the mixture of mortar include (0, 5, 10, 15 and 20%) with constant (W/C) ratio. Also the amount of the fine aggregate used was three times the amount of cement. The results showed that, the compressive strength and splitting tensile strength and water absorption of the mortars for (replacement) gives better properties than mortar without replacement in all tests. Best enhancements in properties for mortars with pozzalanic replacements were achieved at (15%) for (RHA) and 10% for (RBP) replacement from weight of cement.

This study involves adding nano materials and interaction with cement mortar behavior for several mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5). The effects of adding nano materials on the microstructure of cement mortar were studied by (Scanning Electronic Microscopy (SEM) and X-Ray (for samples at different curing time 28 and 91 days. Small ratio replacements of nano particles (SiO2 or Al2O3) were added to Ordinary Portland Cement (OPC) type (I). The percentage of nano materials additives replacement by weight of ordinary Portland cement includes (1, 2, 3, 4 and 5%) for both types of nano materials with constant (W/C) ratio, also the amount of the fine aggregate used was three times the amount of cement. The results showed that, the mortar consist of both nano materials had better microstructure than mortar without nano materials in all test. Best enhancements in properties and microstructure for mortars with nano silica were achieved with (3%) additives while were achieved with nano alumina at (2%) additives.

Natural fibers and particles reinforced composites are being broadly used due to their bio and specific properties such as low density and easy to machine and production with low cost. In this work, water absorption and mechanical properties such as tensile strength, flexural strength and impact strength of recycled jute fibers reinforced epoxy resin were enhanced by treating these fibers with alkaline solution. The recycled jute fibers were treated with different concentration of (NaOH) solution at (25 0C) for a period of (24) hours. From the obtained results, it was found that all these properties are improved when fibers treated with (7.5wt% NaOH) related to untreated fibers. Conversely, the mentioned properties of composites decreased after fibers treated with (10wt% NaOH). In addition, the hybrid composite with recycled jute fibers and recycled walnut shell powder showed obvious enhancement in the above-mentioned properties.

Polymer nanocomposites (PNC) structures are promising materials due to their novel properties. However, many of their characteristic physical, mechanical, and chemical behavior have not been quantified. Depending on the interface interactions between polymeric chains and clay sheets, various classes of polymer/clay nanocomposite exist: Intercalated, flocculated and exfoliated nanocomposites. In this work, we present an experimental study of poly(vinyl alcohol) (PVA)-cloisite 93A followed by a classical molecular dynamic (MD) simulations. The structural properties of the system were studied using X-ray diffraction (XRD), nanoscanning electron microscopy (NSEM). Both revealed intercalation between PVA chains and cloisite 93A nanoclay. Another evidence of the intercalation between PVA and cloisite 93A nanoclay was realized from the differential scanning calorimetry (DSC) which confirmed as surge in crystallinity upon intercalation. A main focus for the intercalated structure was to investigate the impact of nanofillers content on the mechanical performance. Intercalation significantly influenced both Young's modulus and the % of elongation of PVA/cloisite 93A blends. Young's modulus and tensile stress were raised with the content of the filler content up to 3 wt%. For higher content, opposite observations are addressed owing to the formation of aggregates of nanofillers and as consequence construction of microvoids. From the MD simulations, the intercalation has been shown by the increase of the d-spacing with the clay loading. By calculating the density profile, it has been demonstrated that in case of low clay loading, the cloisite 93A has its nitrogen groups on the clay surface and the long tails form layers. For the high loading of clay, nitrogen and carbon groups are together on the surface. Young modulus calculated theoretically follows the same experimental trend where an increase of the values has been observed with a clay loading up to 3 wt%, followed by a decrease of the values for higher clay loading. J. VINYL ADDIT. TECHNOL., 25:172181, 2019. This paper was made possible by an NPRP 09-260-1-048 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. We are also grateful to University College London for using their high performance computing facilities. Scopus

Recently, works have been focusing on suppression of the segmented cylindrical marine riser vibration caused by vortex-induced vibration experimentally as an open loop active vibration control (OLAVC) model. The main objective of this research is employing the OLAVC theory using double control rods driven by double motors as an electromechanical actuator at two locations which are: control rods located beside (CRBR) and in front–back (CRFBR) to the riser. Passive control technique has been verified before employing the power to the motor for both locations. The electromechanical actuators consisted of double control rods driven by double motors (12 V DC) and connected by couplings. The results revealed that the passive control technique was inadequate to suppress the cylinder vibration in both locations. Therefore, OLAVC techniques were developed with four voltages: 6, 8, 10, and 12 V which are, respectively, equivalent to 50, 75, 83, and 100% of the motor power to rotate the control rods. Eventually, a motor counter-clockwise (CCW) direction of rotation provided a better suppression compared with the clockwise direction. Moreover, an OLAVC system seemed to be adequate to reduce the vibration at all the supplied voltages at CCW direction and the maximum suppression has been obtained at 12 V for all actuator positions and water flow speeds where the maximum vibration suppressed up to 65.13 and 69.81% at the CRFBRP and CRBRP positions, respectively, with superior performance of CRBR position.

This paper presents an experimental investigation on the behavior of bubbled wide reinforced concrete beams with different shear steel plate spacing. Four specimens with the dimensions of 215x560x1800mm are investigated. The variables studied in this work is using the 10mm stirrups with 125mm spacing and 3mm thickness steel plate with spacing 125, 166 and 250mm instead of reinforcing stirrups. Shear steel plates is good alternative for replacing the stirrups and gives increasing in yield and ultimate loads with 17% and 18% respectively and decreasing the deflection by 8% at yield and 12% at ultimate. Moreover decrease the strain in longitudinal reinforcement by 8% at yield and 24% at ultimate, and reduced the total weight by 2.7%. By increasing the spacing of shear steel plate by 33% and 100%, the results showed that the yield load reduced to 3% and 4% respectively, but the deflection was increased with 37% and 20% (at yield). The strain in interior legs is more than the strain in exterior legs by 189%, 142% and 52% at yield for spacing 125, 166 and 250mm respectively. ACI 318-14 [1] and EC 2 [2] codes give a predicted deflection more than the experimental deflection by 26% and 30% on average respectively

Enhanced gas recovery methods such as foamed CO2 are recommended for depleted gas reservoirs. Viscoelastic surfactant (VES) is a form of a surfactant used for forming CO2 foam. In this study, the impact of VES on CH4 and CO2 retention and adsorption in calcite rock samples was studied. Crushed samples of Indiana limestone rocks of average particle size (125-250 ?m) were used in the static adsorption experiments. To study the effect of VES on CH4 and CO2 adsorption, 50% of the crushed samples were conditioned in a solution of NaCl of 0.1 vol % surfactant. X-ray diffraction shows that the rock samples are 99.99% calcite and traces of quartz. The gas adsorption experiments were performed at different temperatures; namely; 50, 100, and 150 �C and at a pressure of 45 bar. At 50 �C, the plain calcite samples adsorbed more CH4 and CO2 compared to that treated with VES. However, at 100 and 150 �C, the plain sample adsorbed much less CH4 and CO2 than the treated sample. This means that at higher temperatures (100 and 150 �C) VES enhanced the adsorption of both CO2 and CH4 on the rock surface. Thermodynamic investigations showed that the process of gas adsorption in the plain samples was exothermic with ?Hads of -13.5 and -16.7 kJ/mol for CO2 and CH4, respectively, and at 50 �C the adsorption was spontaneous with ?Gads of -0.425 for CH4 and -2.599 for CO2. In contrast, at higher temperatures (100 and 150 �C), the adsorption of CO2 and CH4 on surfactant treated sample was spontaneous and endothermic with corresponding ?Hads of 36.2 and 60.1 kJ/mol and ?Gads of -4.701 and -0.581 for CO2 and CH4, respectively. The adsorption of CO2 was three times that of CH4 because of the high affinity of calcite to CO2. Because of the multilayer adsorption on both samples, Freundlich isotherm was found to be the best model that fits the experimental data of calcite with both CO2 and CH4 at different temperatures. Dynamic adsorption experiments were carried out using gas coreflooding system with the same calcite cores used in the static adsorption experiments. The results of this study showed that carbonate rock samples conditioned in the surfactant solution have great adsorption potential for CO2 and are excellent candidates for CO2 sequestration. However, surfactant promoted high CH4 adsorption at 100 and 150 �C, and this will reduce the natural gas recovery. In contrast, using viscoelastic surfactant at low-temperature reservoirs (50 �C) reduced CH4 adsorption by blocking the active adsorption sites in the carbonate rock samples, and this will increase the gas recovery. - 2018 American Chemical Society. Support from the College of Petroleum Engineering and Geosciences at KFUPM is acknowledged. The authors also acknowledge the support of Qatar National Research Fund (a member of Qatar Foundation) through Grant No. NPRP10-0125-170235. The findings achieved herein are solely the responsibility of the authors. Scopus