Effects Of Different Loads Research Articles

Hydrophobic‐functionalized ZIF‐8 nanoparticles incorporated PDMS membranes for high‐selective separation of propane/nitrogen

AbstractIt is still a great challenge to prepare high performance mixed matrix membranes (MMMs) because of the difficulty in finely tuning the compatibility between filler and organic phases. In this work, ZIF‐8 nanoparticles hydrophobically functionalized by 5, 6‐dimethylbenzimidazole (DMBIM) via shell ligand exchange (SLE) reaction were incorporated into polydimethylsiloxane (PDMS) matrix to fabricate defect‐free MMMs. Organic‐–inorganic interface compatibility was realized because of more abundant organic ligands from DMBIM. The effects of different loadings on membrane microstructure and gas separation performance were investigated systematically. A significantly enhanced C3H8/N2 separation performance with C3H8 permeability over 2.10 × 104 Barrer (91 % higher than that of pure PDMS membrane) and C3H8/N2 selectivity of 99.5 (116 % higher than that of pure PDMS membrane) were achieved. Additionally, the as‐prepared membrane also exhibited excellent stability during long term operation. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Creep response of a LDPE‐based nanocomposite

ABSTRACTPolymer nanocomposites and their behavior have been widely investigated by several paths, including mechanical, rheological, and permeability tests, finding that several parameters (such as the polymer matrix, the nanofiller, their amounts, the presence of compatibilizers, processing parameters, etc.) can influence the main properties. However, less information is available regarding the creep response of polymer nanocomposites; in particular, few or no data are reported about the combined effect of different loads and different temperatures. In this article, the creep behavior of a low density polyethylene/organomodified clay nanocomposite has been investigated. The characterization of viscoelastic response has taken into account both the effects of applied load and temperature, which are often considered separately. Dynamic–mechanical and structural analysis was also performed in order to get a deeper understanding of the involved phenomena. The nanocomposite showed lower creep deformations (up to ∼20%) and the relative differences with the neat polymer matrix were found to be increasing upon increasing the applied load (up to ∼24%) and the temperature (up to ∼38%). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44180.

A new method to quantify breach sizes for the flood risk management of concrete arch dams

When predicting dam‐break floods and the associated risk zones for the flood risk management of dams, the breach size must be determined by considering the complex structure of the dam body under the effects of different loads. To predict the breach size quantitatively, this article proposes the concept of an element group, comprising a group of elements through the dam body. The dam‐body safety status is simulated by using the three‐dimensional (3D) finite element model ANSYS and is quantified by the element reliability index β for various loads such as hydraulic and earthquake loads. A new structural reliability method for calculating the breach size was developed to quantitatively predict the failure likelihood of a dam. This new method is more intuitive and reasonable than the point safety factor k. It allows for a more accurate and quantitative prediction of the breach size of new or existing dams. An existing Roller Compacted Concrete arch dam was taken as an example to demonstrate the applicability of the new method.

Erratum to: Investigating the Effect of Water Uptake on the Tribological Properties of Organoclay Reinforced UHMWPE Nanocomposites

Ultra-high molecular weight polyethylene (UHMWPE) nanocomposites reinforced with different loadings (0.5, 1.5 and 3 wt%) of C15A organoclay are fabricated. Water uptake tests at an elevated temperature of 70 °C are performed to evaluate the effect of different loadings of nanoclay on the water absorption by the nanocomposites. It is observed that the water uptake by the nanocomposites reduced with an increase in the concentration of the nanoclay. A 21 % reduction in the water uptake is observed for the UHMWPE nanocomposites reinforced with 1.5 and 3 wt% of C15A, respectively, as compared to pristine UHMWPE. This reduction is attributed to the improvement in the barrier properties of the nanocomposites with the addition of nanoclays. Wear tests are also conducted before and after water uptake to investigate the effect of water absorption on the tribological properties. Organoclay composites showed enhanced performance as compared to pristine UHMWPE even after water absorption. This improvement is attributed to the reduced water absorption of organoclay composites leading to less softening and plasticization of the polymer, resulting in better wear resistance. However, among the different loadings of nanoclays, it is observed that the 1.5 wt% of C15A reinforcement showed the best tribological performance even after water uptake with 41 % reduction in the wear rate and a 20 % reduction in the coefficient of friction when compared to pristine UHMWPE.

Effects of Different Load with Vary Lubricant on the Friction Coefficient and Wear Rate Using Pin on Disk Tribometer

A study has been created on the wear rate and friction constant for various material under the impact of load and material where the equipment pin on disk has been used to investigate the specification on the wear and constant of friction (COF) theory. The issues occur because of the metal-to-metal contact once interaction between two surfaces creates friction, wear and heat. It’ll cause every element life shortened, economically wasted, surface damage and cracks. This paper evaluates via pin on disc tribometer using SKD II and aluminum alloy, A 5083 as work pieces material. The test was tested using different type of lubricant (palm olein and mineral based oil) with different load. The result shows palm olein is more than mineral-based oil for constant friction as sliding speed increased and wear scar diameter lubricated with palm olein lower at low and high speed compared to the oil. As a conclusion, palm olein has better performance properties in terms of friction reduction (coefficient of friction) and wear resistance (anti-wear properties) at low and high speed. Pin that lubricated with palm olein showed small wear scar diameter compared to the mineral based oil. Therefore, palm olein has risk to use as a lubricant of mating components.

The effect of open kinetic chain knee extensor resistance training at different training loads on anterior knee laxity in the uninjured

BackgroundThe commonly used open kinetic chain knee extensor (OKCKE) exercise loads the sagittal restraints to knee anterior tibial translation. ObjectiveTo investigate the effect of different loads of OKCKE resistance training on anterior knee laxity (AKL) in the uninjured knee. Study designnon-clinical trial. MethodsRandomization into one of three supervised training groups occurred with training 3 times per week for 12 weeks. Subjects in the LOW and HIGH groups performed OKCKE resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Subjects in the isokinetic training group (ISOK) performed isokinetic OKCKE resistance training using 2 sets of 20 maximal efforts. AKL was measured using the KT2000 arthrometer with concurrent measurement of lateral hamstrings muscle activity at baseline, 6 weeks and 12 weeks. ResultsTwenty six subjects participated (LOW n = 9, HIGH n = 10, ISOK n = 7). The main finding from this study is that a 12-week OKCKE resistance training programme at loads of 20 sets of 2RM, leads to an increase in manual maximal AKL. ConclusionsOKCKE resistance training at high loads (20 sets of 2RM) increases AKL while low load OKCKE resistance training (2 sets of 20RM) and isokinetic OKCKE resistance training at 2 sets of 20RM does not.

Investigating the effects of different loadings of a nanostructured hyperbranched polymer on the kinetic parameters of disperse dyeing of modified poly(ethylene terephthalate) sheets

The kinetic parameters of disperse dyeing of polyethylene terephthalate (PET) sheets modified by a nanostructured hyperbranched polymer were investigated in terms of dyeing rate constant, time of half-dyeing, diffusion coefficient, and activation energy of the diffusion. The results were compared with those of pristine PET. The surface morphology, surface structure, and thermal properties of modified PET sheets were also studied by atomic force microscopy (AFM), attenuated total reflectance infrared spectroscopy (ATR-FTIR), and differential scanning calorimetry (DSC). Results indicated that the crystallinity and glass transition temperature of modified samples were decreased compared with that of the pristine PET. The diffusion coefficient of dye molecules increased by increasing temperature of dyeing. The highest diffusion coefficient was obtained for the modified PET sample containing 2 wt% hyperbranched polymer while pristine PET sheet showed the lowest one. The activation energy of diffusion of dye into the modified PET sheets was lower than that of the unmodified PET.

A Survey of BPL Technology and Feasibility of Its Application in Iran (Gilan Province)

Recently Broadband over power lines (BPL) has received much attention in communication technology and this is due to economically of sending high data rate services by re-use of power line cables. As data transfer via power lines to final consumer is one of the growing technologies, this study discusses the modeling and optimization of data transfer via power transfer lines and feasibility and adaptation of using this technology in Gilan are investigated. Finally, a model is evaluated for power lines by selection of a cable in selected area (Gilan province) as high speed transfer media and by investigation of the effect of different loads on channel feature, simulation and transfer function between various areas of network are considered. Simulation is done by ABCD transfer matrix and channel frequency response is achieved. This model is useful in description of frequency response of lines of this network and application in design of data transfer system.

Polymer nanocomposite dielectric based on P(VDF-TrFE)/PMMA/BaTiO3 for TIPs-pentacene OFETs

TIPs-pentacene OFETs were fabricated on a plastic substrate using polymer nanocomposite dielectric. The blend polymer P(VDF-TrFE)/PMMA (30wt%) was used as polymer matrix and BaTiO3 nanoparticles modified by 3-glycidoxypropyltrimethoxysilane (GPTMS) were dispersed as ceramic fillers. The effects of different loadings of BaTiO3 on the surface morphology and electrical properties of dielectric films were investigated. The formulation of screen-printable dielectric ink of P(VDF-TrFE)/PMMA/BaTiO3/Silica (SII) was achieved by adding fumed silica as the viscosity modifier. TIPs-pentacene OFETs using SII as the gate dielectric features a mobility of 0.01cm2/Vs, and having a threshold voltage of −6V. This screen-printable dielectric ink is promising for low operating-voltage fully-printed OFETs.

Effect of Stannum on Properties of Graphite/Stannum Composite for Bipolar Plate

Over the past decade, rapid progress has been made in the understanding and development of Hybrid Conductive Composite (HCC) to be used as bipolar plate, one of the most important components in Polymer Exchange Membrane Fuel Cell (PEMFC). The formation processes of HCC and loading ratios of composite have significant effects on their properties especially electrical and mechanical properties. Thus, the research focuses on Graphite (Gr) as a filler and Stannum (Sn) as a binder in fabrication of HCC as a bipolar plate. The fabrication process began with Gr and Sn needed to dry mixed used ball mill with several ratios of loading, which are 60/40, 70/30 and 80/20 respectively. The shape of this composite was molded with a diameter of 25 mm through hot compression machine to form discs. The effect of different loadings on the properties such as electrical conductivity, bulk density and microstructure were observed and confirmed to be able to meet the DOE target properties as PEMFC bipolar plates. The result showed that Gr/Sn composite with 20 wt% Sn had the highest electrical conductivity which was 720 S/cm. In the other side, the bulk density showed decrement as Sn contents increased from 1.71 to 1.48 g/cm3. The findings promise an enhanced performance of HCC as a bipolar plate to be used in PEMFC which is beneficial for mobile and portable application industry. A further study on agglomeration and the mechanical properties such as the flexure strength and hardness should be pursued.

The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee.

To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee. Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12). The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups. Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles. Randomised controlled trial, Level II.

Design and experiment of a compact quasi-zero-stiffness isolator capable of a wide range of loads

This paper proposes the design and experiment of a vibration isolator capable of isolating a wide range of loads. The isolator consists of two oblique springs and one vertical spring to achieve quasi-zero stiffness at the equilibrium position. The quasi-zero-stiffness characteristic makes the isolator attenuate external disturbance more at low frequencies, when compared with linear isolators. Unlike previous studies, this paper focuses on the analysis of the effect of different loads and the implementation of an adjustment mechanism to handle a wide range of loads. To ensure zero stiffness under imperfect stiffness matching, a lateral adjustment mechanism is also proposed. Instead of using coil springs, special planar springs are designed to realize the isolator in a compact space. Static and dynamic models are developed to evaluate the effect of key design parameters so that the isolator can have a wide isolation range without sacrificing its size. A prototype and its associated experiments are presented to validate the transmissibility curves under three different loads. The results clearly show the advantage of quasi-zero-stiffness isolators against linear isolators.

Eletrocardiografia contínua (Holter) em cães saudáveis submetidos a diferentes exercícios físicos

O presente trabalho teve como objetivo avaliar os efeitos de diferentes cargas de exercícios físicos no comportamento da frequência e do ritmo cardíaco de cães saudáveis, ao longo das 24 horas de gravação Holter. Utilizaram-se 23 cães, sem restrição de sexo, idade ou raça, dos quais 15 foram submetidos a atividades físicas e pertenciam ao grupo controle. Os resultados mostraram alterações na frequência cardíaca durante as atividades propostas, em que se alcançaram 174±27bpm durante a caminhada leve, 148±30 durante a atividade com bola e 165±26 durante o Cooper. Ademais, observaram-se arritmias, incluindo bloqueios atrioventriculares e extrassístoles e maior número e duração de pausas (até 5s) em repouso, além de uma menor variação na frequência cardíaca (FC) durante o período de sono dos animais do grupo experimental. Esses eventos não foram observados no grupo controle, o que sugere que o exercício físico extenuante interfere na modulação autonômica do coração, podendo predispor a arritmias importantes.

Amounts of logging residues affect planting microsites: A manipulative study across northern forest ecosystems

We quantified the effects of different loads of forest logging residues on the microenvironment (soil temperature, soil volumetric water content, competing vegetation cover, and available nutrients) of planted hybrid poplars one year after planting, and assessed the corresponding seedling growth until the third growing season. In four experimental plantations across Quebec (Canada), we used a factorial design of four residue loads that were applied at the tree-level over three planted species: hybrid poplars (Populus spp.), black spruce (Picea mariana (Mill.) BSP), and either jack pine (Pinus banksiana Lamb.) or white spruce (Picea glauca (Moench) Voss), depending upon the site. Logging residues linearly decreased competing vegetation cover on two of four sites and reduced fluctuations in soil temperature on all sites. Logging residues also decreased summer soil temperatures at all sites through a negative quadratic effect. On one site, the frequency of freeze–thaw cycles increased under logging residues, while logging residues increased soil water content on another site, for certain measurement events. Logging residues did not affect available nutrients. Seedlings showed no consistent growth response to logging residues for three years after planting, except for a beneficial effect of logging residues on hybrid poplar growth on one site. Because logging residues affected seedling microclimate and competing vegetation, their maintenance and on-site spatial arrangement on site could be used to manipulate the growing conditions for planted trees.

Study on pine biomass air and oxygen/steam gasification in the fixed bed gasifier

The pine biomass gasification under air and oxygen/steam atmosphere was experimentally studied in a fixed bed reactor. The effects of air flow, gasification temperature, oxygen concentration, steam flow and the catalytic cracking reaction temperature on production distribution were investigated. The results indicate that the H2 content reaches the maximum at the gasification temperature 850 °C for a given air flow. Comparing with air-gasification atmosphere, the lower heating value (LHV) of produced syngas is higher (up to 8.76 MJ/Nm3) under oxygen-enriched gasification atmosphere. And the introduction of steam to the oxygen-enriched gasification leads to a higher H2 content and LHV of produced synthesis gas. Additionally, the syngas content increases significantly with increasing catalytic cracking reaction temperature when Ni–Al2O3 catalyst was employed in catalytic cracking process. The results also reveal that the steam reforming reactions of methane and carbon dioxide are enhanced over Ni–Al2O3 catalyst. The effects of different loading of metal oxide additives to Ni–Al2O3 catalyst on the catalytic activity were discussed, and it is found that the Fe2O3/Ni–Al2O3 catalyst shows the best catalytic activity and the H2 content achieves the maximum value of 39.21 vol.%.

Effect of Nanoindentation Loading Rate on Gold Ball Bond

Nanoindentation tests with loading rates of 0.05 mN/s, 0.1 mN/s, 0.5 mN/s, and 1.0 mN/s were conducted on the Au ball bond. The effect of different loading on the Au ball bond were analysed based on qualitative and quantitative results. The displacement burst was more pronounced with the increment of loading rates. The increase of hardness value and the decrease of the reduced modulus value when the loading rate was increased are due to the effect of creep. It was found that the loading rate of 0.5 mN/s is the appropriate and stable value for the nanoindentation test on the Au ball bond.

Processing, Thermal Behavior and Tensile Properties of PLA/Thermoplastic Starch/Montmorillonite Nanocomposites

Thermoplastic starch, polylactic acid glycerol and maleic anhydride (MA) were compounded with natural montmorillonite (MMT) through a twin screw extruder to investigate the effects of different loading of MMT on tensile properties and thermal behavior of the nanocomposites. Tensile results showed an increased in modulus, tensile strength and elongation at break. However, beyond 3phr of MMT the modulus of samples decreased because the MMT particles agglomerated. The thermal properties were characterized by using differential scanning calorimeter (DSC). The results showed that MMT increased melting temperature and crystallization temperature of matrix but reduction in glass transition temperature was observed.

The effects of operating temperature on current density distribution and impedance spectroscopy by segmented fuel cell

The printed circuit board (PCB) technique is one of the In-situ segmented cell measuring techniques which can provide real-time, accurate current density distributions and reflect the uniformity of the internal electrochemical reaction in the fuel cell. The PCB technique and electrochemical impedance spectroscopy (EIS) were utilized to study the effects of operating temperature on the current density distributions and membrane resistances. The operating temperatures were respectively chosen at 50, 70 and 90 °C, operated at the load of 10 A, to observe the polarization curves, the internal segmented current density distributions and membrane resistances. The polarization curves showed that at 70 °C, the performance of fuel cell was the best and the current density distribution was evenly distributed. The results of EIS also demonstrated that at 70 °C, the resistance of fuel cell was the lowest. The effects of different loads on the current density distribution at 70 °C were also studied. It showed that with increasing loads, the current density distributions became more and more unevenly. This was mainly because the increasing of loads would produce more water at the exit, which led to the hinder of the air circulation, and then it induced to the increase of inhomogeneity of the current density distributions.

Research on Friction and Wear Properties of Ti(C,N)/Fe Composites

The effect of different load, revolving speed ,content of Ti(C,N) and sintering process on the friction coefficient and wear rate of Ti(C,N)/Fe composites was investigated systemically. Besides, the wear morphology of Ti(C,N)/Fe composites were researched with an environment scanning electron microscopy(SEM),and the phase composition were studied by X-ray diffraction(XRD).The research shows that the wear mechanism of Ti(C,N)/Fe composites are abrasive wear and adhesive wear.

Catalytic epoxidation of cyclohexene over mesoporous-silica immobilized Keggin-type tungstophosphoric acid

A series of aminosilylated mesoporous silica (SBA-15) samples with different contents of (3-aminopropyl) triethoxysilane (APTES), synthesized using a simple one-pot method, were used as hosts for immobilization of Keggin-type 12-phosphotungstic acid (H 3 PW 12 O 40 ). The loading of H 3 PW 12 O 40 increased with increasing content of grafted APTES. The obtained materials were calcined at different temperatures, and the tungsten species were highly dispersed inside the SBA-15 channels. The catalytic activities of these samples were tested in heterogeneous oxidation of cyclohexene using H 2 O 2 as the oxidant. The effects of different loadings and treatment temperatures on the activities of the catalysts were also investigated. The catalysts calcined at 400 °C showed high catalytic activities and reusabilities. 采用共合成法制备了一系列不同硅氨基含量的介孔氧化硅 SBA-15, 在其孔道中引入 Keggin 型钨磷酸, 且其含量随硅氨基含量的增加而增加. 考察了不同处理温度下杂多酸的热稳定性, 发现焙烧后钨物种能在 SBA-15 孔道内高度分散. 以 H 2 O 2 为氧化剂, 研究了该催化剂在环己烯环氧化反应中的催化活性, 考察了杂多酸负载量和焙烧温度对催化活性的影响. 结果表明, 400 °C 处理后的钨磷酸催化剂具有高的反应活性和重复使用性能. A simple method was used to prepare mesoporous-silica- immobilized Keggin-type tungstophosphoric acid. The resulting catalysts showed high catalytic activities and reusabilities in heterogeneous oxidation of cyclohexene using H 2 O 2 as the oxidant.