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A high-strength binary Mg–15Gd alloy plate, prepared by the conventional extrusion, warm-rolling and aging, exhibits an excellent mechanical property with 504, 518 MPa and 4.5% for yield strength, ultimate tensile strength and elongation, which is mainly attributed to the nano substructure with boundary segregation of Gd atoms, the high-density nano clusters induced by dislocations in the interior of grains, the high-density dynamical precipitates with submicron size, and the strong basal texture. A new strengthening mechanism involving the nano substructure with Gd segregation, high-density nano Gd clusters induced by dislocations, and high-density dynamical precipitates has been found in Mg–Gd binary alloys. [ABSTRACT FROM AUTHOR]

Isoalantolactone is one of the major active ingredients from Inula helenium L. However, it is low cost-effective to isolate isoalantolactone from Inula helenium L. In this study, we optimized the extraction strategy and obtained a mixture of active ingredients with exact proportion (termed as F35), which were alloalantolactone, alantolactone and isoalantolactone at the ratio of 1/5/4 respectively. The anti-tumor activity of F35 was compared with isoalantolactone on pancreatic cancer cells. As a result, F35 showed nearly the same anti-proliferation activity as isoalantolactone in two cell lines. Both F35 and isoalantolactone could induce mitochondrion-related apoptosis at the concentration of 6 μg/ml. In addition, F35 inhibited colony-formation and migration of PANC-1 and SW1990 cells. To conclude, F35 exhibited similar anti-proliferation and anti-migration effect as isoalantolactone on two pancreatic cancer cell lines, suggesting that alantolactone or alloalantolactone might have comparable anti-tumor effect as isoalantolactone. [ABSTRACT FROM AUTHOR]

Urban parks not only improve the urban ecology but also provide cultural ecosystem services to city dwellers. This study investigated the relationship between cultural ecosystem services provided by urban parks and visitors' perception of urban park from the perspective of landsenses ecology. A perceptual indicator system was developed following the analysis of landsense elements among the park elements, for four sensory dimensions. A perceptual assessment model was established using the Importance-Performance Analysis (IPA) method, which could be used to divide the perceptual indicators into five grades. We found that the importance level of perceptual indicators was influenced by the type of park elements and the functional area of the visitors' sensory apparatus. On the one hand, park elements that are common or can be perceived easily receive more attention. On the other hand, among the distance receptors, wider functional area might be related to the higher importance level of the perceptual indicators; the immediate receptors also have considerable influence on perception since visitors contact with the environment directly through these. The most important indicators were related to vision and touch, including 'vision of plants', 'vision of water', 'feel of sunlight', 'touch of roads', and 'sound of animals'. Furthermore, we conducted an assessment on landsense satisfaction of a typical urban park in Beijing, suggesting ways to improve visitors' perception of urban parks from the perspective of landsenses ecology. The assessment showed that the urban park design and management practices could be improved to increase visitors' satisfaction. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses (BMGs), like other glasses, soften in the super-cooled liquid region (SCLR). Here in this work, surprisingly, a large expansion is reported occurring in the deep SCLR of a Zr47Cu37Al8Ag8BMG. Nano-crystals (NCs) are found precipitated during the anomalous expansion of Zr47Cu37Al8Ag8, but also in the SCLR of Zr43Cu41Al8Ag8that exhibits a conventional softening. It is found that there is a steep composition and density change at the NCs/amorphous matrix transition region in the former alloy, and this transition region exerts a thermal stress of about 0.15 MPa to the surrounding super-cooled liquid (SCL) and drives the soft SCL to expand severely. [ABSTRACT FROM PUBLISHER]

Previous experiments recognize that substantial heat transfer augmentation is achieved by adding ribbed turbulators after jet impingement with cross flow present. To address fundamental working mechanisms, conjugate CFD simulations are employed for ribs, jet impingement, and their combinations. Flow characteristics and drawbacks for the individual and combined enhancement techniques are highlighted. New analysis on the coupled design arrangement reveals that the counter-rotating vortices generated by the jet flow can energize inter-rib recirculating vortices and promote span-wise convection. With an optimal design combination arrangement, extra heat transfer benefit is achieved beyond that associated with simple superposition of rib and jet impingement techniques. [ABSTRACT FROM AUTHOR]

Na2Ti2Sb2O is a parent compound of the titanium-based oxypnictide superconductors. It possesses a phase transition atTs = 115 K whose nature is still unclear. Here we report a scanning tunnelling microscopy/spectroscopy (STM/STS) study on a Na2Ti2Sb2O single crystal. We observe a lattice distortion on the Na-terminated surface belowTs, which displays a 2 × 2 modulation (superstructure). The modulation vectorsq= (±0.5, 0)and (0, ±0.5)match well with the Fermi surface nesting vectors observed by angle resolved photoemission spectroscopy (ARPES), and also agree with recent X-ray diffraction. A partially opened gap-like feature is present in STS nearEF. This evidences that the lattice distortion is driven by commensurate charge density wave order. Our results suggest the electron–phonon interaction is strong in Na2Ti2Sb2O and could be responsible for the superconductivity in titanium-based oxypnictides. [ABSTRACT FROM PUBLISHER]

BackgroundThe climacteric phase of menopausal transition (perimenopause) is marked by reproductive hormone fluctuations and reduced cognitive capacity. Exercise enhances neurocognitive performance. However, auditory perceptual sensitivity has not been examined. PurposeThis study aimed to determine the effect of aerobic exercise on the response speed (reaction time) and error rate during auditory processing among perimenopausal women. MethodsThree pitches (500, 1000, and 2000 Hz) were used during a simple auditory discrimination task, which was performed before and after exercise. We included 14 perimenopausal women and 17 right-handed young women (aged 46–54 years and 18–22 years, respectively). To achieve similar exercise intensity in both groups, we proposed two types of physical activities for each group. Mixed models statistics were used to analyze the reaction time and error rate before and after training in the two groups. ResultsPerimenopausal women exhibited a significantly longer reaction time than young women during the baseline auditory discrimination task (p < 0.05) but not during the second test. The error rate decreased significantly after exercise among perimenopausal women (p < 0.05) but not among young women. Thus, exercise had a stronger beneficial influence on auditory plasticity or sensitivity for perimenopausal women than for young women. ConclusionThe ability of aerobic exercise to modulate auditory neurocognitive performance differs between the two groups. Aerobic exercise improves auditory discrimination performance specifically for perimenopausal women. These results provide preliminary evidence concerning the acoustic features of middle-aged women, underscoring the importance of exercise for preventing decline in auditory cognitive function in perimenopausal women. [ABSTRACT FROM PUBLISHER]

In the present work, hydrolysis of sweet sorghum bagasse residue using dilute acid was investigated. The sweet sorghum bagasse residue was from pretreatment. Process parameters investigated include reactor temperature, reaction time, and acid concentration in order to find suitable conditions for hydrolysis of the cellulose fraction. The effects of dilute acid hydrolysis were assessed by glucose yield and decomposition products concentration. The highest yield of glucose, 70.10%, was found at the temperature of 170°C, acid concentration of 1.0% (w/w), and a reaction time of 10 min. Meanwhile, 0.99 g/L of acetic acid, 0.22 g/L of furfural, 0.73 g/L of hydro-xymethyl furfural, and 1.60 g/L of levulinic acid were obtained under these conditions, which concluded that the decomposition of glucose was slight and confirmed the selectivity of this dilute acid hydrolysis of the sweet sorghum bagasse residue. The present work aims to take full advantage of the sweet sorghum bagasse residue and obtain glucose solutions with a low concentration of growth inhibitors. [ABSTRACT FROM PUBLISHER]

In this study, the effects of a magnetic field on natural convection heat transfer in an enclosure filled with nanofluid are numerically investigated by using lattice Boltzmann method. The calculations were performed for a wide range of governing parameters. The results show that increase of Rayleigh number and nanoparticle volume fraction improves heat transfer in the enclosure, but an opposite trend is found when Hartmann number increases. The results also indicate that there are critical values for Raleigh number and the magnetic field orientation at which the impacts on flow and heat transfer are the most pronounced. [ABSTRACT FROM AUTHOR]

In this paper, the microstructures of solder alloys were improved by adding trace elements of Ni to BiSbSn solder to enhance Bi-based solder alloys mechanical properties. The spreading areas, tensile strengths and shear strengths of the Bi-5Sb-8Sn-xNi solders with various Ni contents were characterised. The results revealed that after Ni was added to the BiSbSn solder, two new phases occurred: Ni3Sn4 and NiSb2. When the Ni content was 1%, the solder tensile strength was at the highest. When the Ni content was less than 3%, the shear strength increased as the Ni content increased. When the Ni content was more than 3%, the shear strength decreased gradually, primarily owing to the large amounts of impurities and pores introduced by the internal aggregation effect. In summary, when the Ni content was between 1 and 3%, the solders had the most-usable overall properties. [ABSTRACT FROM AUTHOR]

The temperature dependent poling behaviour of MnO2 doped Pb[(Mn1/3,Sb2/3)0·03(Zn1/3,Nb2/3)0·15(Zr1/2,Ti1/2)0·82]O3 lead contain ceramics is investigated in this research. The piezoelectric constant d33 value of the samples poled under 200°C can get to 358 pC N−1. While the d33 value of the samples poled under room temperature is only 102 pC N−1. The piezoelectric constant d33 value and strain level increase more than two times when samples are poled under 200°C. The internal bias field appears quite modest relative to the strain improvement. The origin of the internal bias field is discussed and a mathematical model is proposed to interpret the mechanism. [ABSTRACT FROM AUTHOR]

The phase constitutions of Ti-35·4Nb and Ti-35·4Nb-0·05C (wt-%) alloys with different heat treatments were detected using X-ray diffraction experiments. Compressive properties were tested using a 100 kN MTS testing machine for the two alloys. It was shown that the phases of the as sintered alloys consist of α and β phases. As sintered Ti-35·4Nb-0·05C alloy contains less β phase and more α phase compared with as sintered Ti-35·4Nb alloy. The phases of as quenched alloys are composed of α″ and βM phases. As quenched Ti-35·4Nb-0·05C alloy has more α″ phase and less βM phase compared with as quenched Ti-35·4Nb alloy. As quenched Ti-35·4Nb-0·05C alloy has a lower elastic modulus and yield stress than as quenched Ti-35·4Nb alloy, which is resulted of more α″ phase in as quenched Ti-35·4Nb-0·05C alloy. The elastic modulus and yield stress of as quenched Ti-Nb alloys are less than those of the as sintered Ti-Nb alloys with identical compositions since both α″ and βM phases in as quenched Ti-Nb alloys have lower modulus and yield stress compared to α and β phases. [ABSTRACT FROM AUTHOR]

The increased research and development of thermoelectric materials for energy conversion applications is driven primarily by the need for improved efficiency in the global utilization of energy resources. To facilitate the search for higher efficiency thermoelectric materials, we have developed a suite of complimentary high-throughput screening systems for performing thermoelectric metrology on combinatorial thin films. These custom capabilities include a facility for combinatorial thin film synthesis and suite of tools for screening the Seebeck coefficient, electrical resistance, and thermal conductivity of combinatorial films. The room temperature Seebeck coefficient and resistance are measured via an automated multiprobe apparatus, thus obtaining the power factor,S2σ(whereS= Seebeck coefficient,σ= electrical conductivity). In addition, we are developing a high temperature (>300 K) power factor screening tool. Thermal effusivity (to calculate the thermal conductivity) is measured using a frequency domain thermo-reflectance technique. Using these tools, we are capable of performing power factor and thermal conductivity measurements on 1000 distinct sample-points within 6 hours for each instrument. This paper will detail several application examples using these tools on thermoelectric materials, including composition-spread films, conventional thin films, bulk ceramics, ribbons/tapes, and on single crystals. [ABSTRACT FROM AUTHOR]

A mixture of several typical model compounds was chosen as the bio-oil model. Hydrogen production via catalytic steam reforming of model bio-oil in a two-stage reaction system was studied in this article. Quartz sand was used in the first-stage fluidized bed reactor for primary steam reforming, and Ni/modified dolomite was chosen as the catalyst in the second-stage fixed bed reactor for deep steam reforming. The main influential parameters, such as temperature, steam to carbon ratio, and weight hourly space velocity, were tested in this work. The optimum conditions on hydrogen production were obtained at 800°C; steam and carbon mole ratio, 12; and weight hourly space velocity, 1 h−1. In addition, there was a comparison between a two-stage reaction system and one-stage fixed bed reactor on the optimum condition. It was concluded that H2yield decreased 5.6% in the two-stage reaction system and 9.9% in the one-stage fixed bed reactor after 3 h reaction time; the maximum carbon deposition ratio was 1 and 0.44%, gaseous carbon selectivity dropped from 93.6 and 90.1% to 83.4 and 78.4%. The fresh catalyst as well as used catalyst were analyzed by scanning electron microscopy, which showed that the carbon deposition in the two-stage reaction system is less than that of the one-stage fixed bed reactor. [ABSTRACT FROM PUBLISHER]

In the present work, pretreatment of sweet sorghum stalk using dilute acid was investigated under mild conditions. Process parameters investigated include reactor temperature, reaction time, and acid concentration. Xylose concentration, xylose yield, and decomposition product concentrations are measured. The highest yield of xylose (77.5%) is achieved under optimum conditions. The optimal conditions selected are 0.75% (w/w) acid concentration, 140°C, and 10 min. Using theses conditions, 23.9 g/L of xylose concentration, 0.98 g/L of furfural, and 2.52 g/L of acetic acid are obtained. The decomposition product concentrations are low. [ABSTRACT FROM AUTHOR]

The control of secondary cooling is extremely important for the quality of billet in the continuous casting. In order to minimise the variation in surface temperature and excessive reheating of billet, which have a considerable influence on the formation of cracks and other defects, a real time heat transfer model that can be used for simulation of varying casting operations was developed. In order to verify the dynamic performance of this model, a charge coupled device temperature measurement system that can eliminate the impact of the scales was presented. The actual shell thickness profile and billet temperature were calculated in real time by this model online and were taken into account to feedback control the casting process based on the desired target cooling pattern to improve the existing cooling system. The dynamic control system based on this model was developed and implemented on some caster, and the billet quality was obviously improved. [ABSTRACT FROM AUTHOR]

Glasses in SiO2-Al2O3-B2O3-RO system doped with different Re2O3 (Re = La, Ce, Nd and Sm) at 4·5 mol.-% were prepared by conventional melt quenching technique. Structural, thermal durability and dielectric properties were investigated by using differential thermal analysis, Fourier transform infrared spectroscopy and precision impedance analyser respectively. Chemical durability was evaluated by weight losses of samples after immersion in HCl solution for varying times. The results showed that with increasing ionic radius of Re3+ ions (La3+Ce2O3>Nd2O3>Sm2O3. [ABSTRACT FROM AUTHOR]

The effects of curing temperature on alkali activated slag cement (AAS) were investigated. The results indicate that the impact of the curing temperature is much more significant on the setting time of AAS than that of ordinary Portland cement. Curing at below normal temperature (∼7°C) greatly prolongs both the initial and final setting times, and also remarkably reduces the early age strength of AAS, whereas it will not lead to significant reduction in late age strengths. Scanning electron microscopy revealed significant difference in microstructures of AAS pastes cured for 28 days, and the compactness of the paste structure increases greatly with the increasing of the curing temperature. [ABSTRACT FROM AUTHOR]

The effect of cement/sand ratio of the original mortar, type of the activators and addition of slag powder on alkali activated recycled cement mortar powder (AARCMP) pastes were studied. The results show that the cement hydrates in recycled cement mortar can be activated by alkali to reconstruct new cementitious substances. Water glass is more effective as an activator than NaOH. Recycled cement mortar with higher original cement/sand ratio yields higher strengths, and addition of slag powder can remarkably increase the strengths of the materials. AARCMP paste with the 28 day flexural and compressive strengths of 7·5 and 45·4 MPa respectively was prepared by replacing 30% slag powder for the recycled mortar powder. Scanning electron microscopy revealed that there is a great difference between the microstructures of the hardened paste of AARCMP and that of ordinary Portland cement. [ABSTRACT FROM AUTHOR]

A combined experimental and numerical study has been conducted to compare the characteristics of free jet flames and confined jet flames from a small ceramic tube burner using liquid ethanol as fuel. The visualization results show that the flame shapes between the free jet flame and the confined jet flame have some differences. An obvious liquid–vapor interface has been found for the confined jet. Numerical results of flame lengths and flame temperature show reasonable agreement with the experimental data within the present parameter ranges. At the same liquid ethanol flow rate, the flame length of confine jet is smaller than that of free jet. For the confined jet, the heat loss is smaller; the flame temperature is higher, so the enhanced diffusion results in a shorter length. [ABSTRACT FROM AUTHOR]

H2production by steam reforming of fast pyrolyzed bio-oil over Ni/MgO-La2O3-Al2O3catalyst was carried out in a fixed-bed reactor by using model compounds (acetic acid, furfural, cyclopentanone, and m-cresol) and real bio-oil as the starting materials. The carbon deposition mechanism was discussed and a model of carbon deposition was built based on the amount of coke formed under different reaction temperatures, reaction times, steam to carbon molar ratios (S/C), and liquid hourly space velocities. The activation energies in the carbon deposition reaction and in the carbon elimination reaction were calculated as 28 and 71 kJ/mol, respectively, in terms of the carbon deposition model employed. [ABSTRACT FROM PUBLISHER]

Ni-Co/Ce-Zr-O catalyst was prepared by incorporating sol-gel and wet impregnation methods. Meanwhile, mechanism of methanol and acetone (model compound derived from bio-oil) catalytic steam reforming over Ni-Co/Ce-Zr-O catalyst were studied. The results indicated that methanol was first absorbed by Ce at the catalyst Ni-Co/Ce-Zr-O and transformed into methoxyl species. Methoxyl group further dehydrogenation produced formate. Part of the formate separating from the Ce atom was combined with the absorbed H atoms to form formic acid. The others were transformed into absorbed CO2after further liberating hydrogen. Finally, absorbed CO2separated from the catalyst. The mechanism of acetone catalytic steam reforming is as follows: first of all, the water molecule is broken up into OH and H under the synergic effect of the carrier and the metal. The OH species is then absorbed by Ce3+, and the H species is absorbed by active metal. Next, the carbonyl group of acetone is absorbed by OH, which is linked to Ce atom, while the methyl of acetone is absorbed by Ni atom; meanwhile hydrogen is released. After that, CO2releases by breaking of the Ce–O bond, then part of the methyls absorbed from the neighboring Ni atoms polymerize to produce C2H4; the others, after water assisted decomposition, produce CO2and H2. [ABSTRACT FROM PUBLISHER]

Ni-Co/γ-Al2O3, Ni/γ-Al2O3, Co/γ-Al2O3, mechanical mixed Ni/γ-Al2O3, and Co/γ-Al2O3catalyst (another name is Ni/γ-Al2O3|Co/γ-Al2O3) were prepared by the wet impregnation method, and the catalytic performance for hydrogen production by catalytic reforming of volatile from biomass pyrolysis over the four catalysts was compared under the condition of different temperatures and weight hourly space velocity. The experimental results show that the catalytic performance of the four catalysts from high to low is Ni-Co/γ-Al2O3> Co/γ-Al2O3> Ni/γ-Al2O3|Co/γ-Al2O3> Ni/γ-Al2O3within the studied temperature and weight hourly space velocity scope. Hydrogen selectivity of 94.83% and hydrogen yield of 120.81 g/kg biomass (dry basis) were obtained over Ni-Co/γ-Al2O3under the condition of catalytic reforming temperature of 825°C and weight hourly space velocity of 0.71 h−1. [ABSTRACT FROM PUBLISHER]

In this article, the integrated process technology is introduced for production of hydrogen, which incorporates pyrolysis of biomass and catalytic steam reforming. The process adopts a fluidized bed reactor for pyrolysis and a fixed bed reactor for steam reforming, in which technological parameters, such as pyrolysis temperature, ratio of steam over biomass, reforming temperature, gas hourly space velocity, catalyst size, and the life of the catalyst, were investigated in order to conclude their effects on the hydrogen production. Results from experiments indicate the concentration of hydrogen in the gaseous product and thus the hydrogen yield increases as both operation temperatures of pyrolysis and reforming increase while catalyst size reduces. The increase in steam over biomass, however, results in hydrogen yield varying from increase to decrease. [ABSTRACT FROM PUBLISHER]

Many oxygen compounds were contained in bio-oil, such as acids, alcohols, ketones, aldehydes, phenols, and sugar. Acetic acid, ethylene glycol, butanone, furfural, and m-cresol were selected as bio-oil model compounds in this article. Hydrogen production was carried out via catalytic steam reforming under the conditions of the mole ratio of steam and carbon = 6, liquid hourly space velocity = 5 h−1, and 600°C with catalyst Ni/MgO. Infrared gas analyzer was used to analyze gas concentration via catalytic steam reforming of model compounds on line, while the liquid products from a collection device were analyzed by gas chromatography/mass spectrum. Intermediates were formed under catalytic steam reforming through elimination and recombination reaction, etc. The intermediates reacted with steam to produce H2and CO2, and then the reactions reached equilibrium in the end. The hydrogen yield of acetic acid, ethylene glycol, and butanone as materials were higher than that of furfural and m-cresol as materials at the same conditions. The lowest hydrogen yield is only 34.0% (m-cresol as feedstock) and the highest hydrogen yield is up to 78.6% (butanone as feedstock). [ABSTRACT FROM PUBLISHER]

Pyrolysis kinetic characteristics of sawdust samples were studied at heating rates of 30, 40, and 50°C·min−1by thermogravimetric analysis. The pyrolysis of sawdust could be divided into five stages, and Sestak's complex mechanism was used to study the mechanism of each stage. The thermal degradation mechanism, activation energy, and frequency factor of each stage were obtained by multi-linear regression using Microsoft Excel. The results showed that the Sestak-Berggren function is very suitable for the mechanism analysis of complex systems. [ABSTRACT FROM AUTHOR]

Biomass fast pyrolysis oil (bio-oil) is considered a promising renewable liquid energy. A feasible upgrading method is co-processing HHDO-oil, which is the heavy fraction of hydrodeoxygenated pyrolysis oil (HDO-oil), with paraffin oil. In this article, kinetic modeling for catalyst deactivation by coke was researched. The results show that the coke is lower by co-processing of HHDO with paraffin oil than other upgrading. Catalyst deactivation is a cascade reaction, the effect of HHDO concentration from 3.18 to 5.08 mol/m3and the effect of temperature from 753 to 793 K were studied. The kinetic model equation of catalyst deactivation is −da/dt= 1.188 × 10−5e18914.85/RT·c0.88·a. [ABSTRACT FROM PUBLISHER]

Biomass gasification to produce syngas was carried out in a fluidized bed reactor and a catalytic fixed bed reactor. The feedstock was sawdust and the cracking catalyst included the calcined dolomite, Ni/dolomite, Ni/modified dolomite, and reforming catalyst. The Ni/modified dolomite catalyst showed better performance and low cost. The optimum technological conditions were as follows: fluidized bed temperature, 1,073 K; catalytic fixed bed temperature, 1,073 K; the mass ratio of steam to biomass, 2.0. [ABSTRACT FROM PUBLISHER]

Biomass fast pyrolysis oil (bio-oil) is considered to be a promising renewable liquid energy carrier. But it cannot be applied in stationary combustion engines, so upgrading is required. A considerable alternative upgrading method is hydrodeoxygenation; the heavy fraction of hydrodeoxygenated pyrolysis oil (HDO-oil) is called HHDO-oil. In this article, HHDO-oil co-processed with paraffin oil in a fixed-bed was studied under the conditions of different temperatures, different weight hourly space velocity, and also different co-processed ratio. It was found that co-processing of 20 wt% HHDO-oil with paraffin oil gave higher yields of liquid and better oil quality than that of the pure paraffin oil cracking. The optimum operating condition was at 520°C, the weight hourly space velocity was 4.0 h−1, and the co-processed ratio was 20%. In this operating condition, it produced the highest yield of liquid, which was 78.65 wt%, including gasoline fraction that was 8.48 wt%, diesel fraction was 37.37 wt%, lubricant fraction was 19.03 wt%, and residue fraction was 13.78 wt%. [ABSTRACT FROM PUBLISHER]

An analytical model is developed in this article for pivoted, oil-lubricated rectangular plane-pad thrust bearings considering the thermal effects of oil viscosity. The model is governed by three dimensionless parameters: the pad length-to-width ratio, the location of the pad pivot, and the bearing load parameter that prescribes lubricant thermal properties and applied load. Analyses were carried out for centrally pivoted bearings of a number of pad length-to-width ratios and a number of bearing load parameters. The results suggest a theory that, for bearings with a square pad or wider, the oil viscosity thermal effect enables a centrally pivoted bearing to develop a hydrodynamic film thickness of about one half of the film thickness that would be developed under isothermal conditions with the pad pivoted at its maximum-load-capacity optimal position. This level of relative film thickness could be developed under all design conditions of practical interest. The theory is fairly general and may be applicable to fan-shaped thrust bearing assemblies with the concept of equivalent length-to-width ratio of the bearing pad. The validity of the theory is modestly evaluated and should be further validated in time through various means and in various settings. [ABSTRACT FROM AUTHOR]

Steam reforming of biomass derived bio-oil liquid products was an available low carbon technology to produce sustainable hydrogen fuel. In this article, a series of nickel-based catalysts have been prepared. To examine the catalytic steam reforming behaviors over these catalysts in a fixed bed reactor system, several typical oxygen-containing chemicals, including acetic acids, furfural, cyclopentanone, and meta-cresol, that were proved to be contained in the bio-oil feedstock, were first selected as model starting materials. In these tests, yields for hydrogen were taken as an index of the catalyst activity and the catalyst that exhibited the maximum activity by hydrogen yields was then used for the bio-oil steam reforming studies. In this work, it was concluded that the catalyst activity reached a maximum hydrogen yield of 90.56% and decreased in an order of Ni/MgO-La2O3-Al2O3 > Ni/MgO-Al2O3 ≈ Ni/La2O3-Al2O3 > Ni/Al2O3. The yield of hydrogen for steam reforming of the whole fraction of the bio-oil reached 70% under 800°C and it only lowered 10%, after 10 hours on stream in a stability test. [ABSTRACT FROM PUBLISHER]

This paper presents a dual-band rat-race coupler with arbitrary power dividing ratio. The dual-band and unequal power dividing characteristics are obtained by using a dual-frequency 180 degree phase shifter with the conventional coupler. Closed-form design equations are derived. The proposed structure can support large power dividing ratio with a wide frequency ratio range. The measured results show that good matching, isolation, power transmission and phase balance can be achieved at two operating frequency bands. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel compact 3-dB quadrature directional coupler by introducing Hilbert curve to the conventional meander line structure. The proposed coupler uses a modified broadside coupled meander lines featuring Hilbert curves to achieve a smaller size. The structure of the coupler is suitable for multilayer printed circuit board (PCB) implementation. The proposed coupler with an operation range of 470 MHz-860 MHz is verified by the accordance of simulation and measurement with a measured return loss and isolation better than 19 dB and exhibiting a coupling of 3.4±0.5 dB in the working frequency range. The dimension of the manufactured coupler is 11.50 mm × 8.90 mm × 1.70 mm. It is the smallest coupler to the authors' knowledge in the frequency range of 470-860 MHz. [ABSTRACT FROM AUTHOR]

Four bifunctional catalysts were prepared by physical mixing of a commercial methanol synthesis catalyst (JC207 catalyst, a catalyst for methanol synthesis, which has been industrialized in China) with zeolite HZSM-5 (Si-Al ratios of 25, 38, 50, 150) as a methanol dehydration catalyst. The bifunctional catalyst (JC207/HZSM-5 [Si/Al = 38]) showed better performance, which can be attributed to more acidic sites with moderate strength of zeolite, and which can control methanol dehydration rate, which is a rate determining step. [ABSTRACT FROM AUTHOR]

HZSM-5 zeolites modified by MgO, CaO, and ZnO were prepared by impregnation and bifunctional catalysts were prepared by modified HZSM-5 zeolites and JC207 catalyst (a catalyst for methanol synthesis, which has been industrialized in China). Evaluation of catalytic activity was conducted in a fixed-bed reactor. Results show, with proper basic oxide-modified zeolite, a Br⊘nsted acid site (strong acid sites) shift to Lewis acid site (weak acid sites). Weak and less strong acid sites on HZSM-5 zeolite are activity centers for the formation of dimethyl ether (DME), whereas strong acid sites for by products such as hydrocarbons. Consequently, the selectivity of CO2 and hydrocarbons decrease, especially with zeolite modified by CaO. [ABSTRACT FROM AUTHOR]

Numerical simulation is carried out on pressure loss of an inner-cone flowmeter by fluid software. The experimental medium of numerical simulation is gasoline. An inner-cone flowmeter and orifice plate flowmeter are frequently used in product pipeline. In the condition of the same flow area, the two experimental results of pressure loss are compared. As a result, the pressure loss of the inner-cone flowmeter is only 22% of the orifice plate flowmeter. The application of inner-cone flowmeter, in measuring mixing flowrate in the product pipeline, can reduce energy consumption. [ABSTRACT FROM AUTHOR]

A series of control parameter researches of differential evolution algorithm (DE) and adaptive DE (ADE) for a wideband six-element Yagi-Uda antenna optimization is presented. A method of moments code (NEC) was used to evaluate each of the antenna designs generated by ADE and DE. The optimized Yagi-Uda antenna is fabricated and measured to validate the efficiency and the flexibility of the parameter analysis. The simulated and measured impedance bandwidth of VSWR < 1.5 achieves 14.0%, which trebles the bandwidth of the Yagi-Uda antenna with a driven dipole element. The measured maximum antenna gain across the operating frequency band reaches 12.75 dB. Measured results of the fabricated antenna prototype is in good agreement with simulated results. Numerical and measured results confirm that the proposed ADE method is superior to or at least competitive with the conventional DE in terms of convergence speed and solution quality. [ABSTRACT FROM AUTHOR]

Theory suggests that in the long term, gentrification-which I define as the phenomenon where wealthier individuals move into lower-income areas-should decrease neighborhood crime. In the short term, however, anecdotal evidence indicates that gentrification actually increases crime, perhaps due to the relative difference in status between newcomers and existing residents, and to increased opportunities for criminal behavior. Further, consumers' choice of residential location depends on crime rates, creating simultaneity that likely biases estimates that overlook this concern. I exploit the 1994 Northridge earthquake in Los Angeles and subsequent short-term government-sponsored home financing incentives as an instrument to control for this endogeneity. The exogenous event induced middle- and upper-income individuals to purchase homes in earthquake-affected low and moderate-income neighborhoods, which I argue is independent of the influence of crime. The results show that in the short term, gentrification increases assaults, robberies, automobile thefts, and thefts from automobiles. [ABSTRACT FROM AUTHOR]

Six Lewis acid ionic liquids were synthesized and employed as extractants for desulfurization of the model oil containing dibenzothiophene (DBT). Very promising ionic liquid was 1-butyl-3-methylimidazolium chloride-FeCl3 ([bmim]Cl/FeCl3), which performed best in the studied ionic liquids under the same operating conditions. It can remove DBT from model oil after continuous extraction for four steps, and the desulfurization efficiency can reach 97.9% under mild reaction conditions. Other sulfur-containing compounds were also investigated. The used ionic liquid could be regenerated six times without a significant decrease in activity. [ABSTRACT FROM AUTHOR]

A green extraction and catalytic oxidative desulfurization (ECODS) system composed of simple tungsten-containing catalyst, 30 wt% H2O2, and ionic liquids was discovered suitable for the deep removal of dibenzothiophene (DBT) in simulated diesel. In the case of the system comprising Na2WO4 · 2H2O, 30 wt% H2O2 and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), the removal of DBT could reach 99.7% at 60°C for 3 hr, which was superior to mere solvent extraction with ionic liquid or catalytic oxidation without ionic liquid. This desulfurization system could be recycled five times with a small decrease in activity. [ABSTRACT FROM AUTHOR]

Small organic dyes have been applied widely in fluorescence imaging techniques for biomedical research. We investigated the cytotoxicity of a novel fluorescent dye, trans-4-( N-2-hydroxyethyl- N-ethyl amino)-4′-(dimethyl amino) stilbene (DMAHAS), on human hepatocellular carcinoma (HepG2) cells using methyl thiazolyl tetrazolium(MTT), a neutral red assay, a Coomassie brilliant blue assay, and flow cytometric analysis. Our results showed that DMAHAS had live cell permeability, stable cytosolic localization and no significant cytotoxicity to HepG2 cells. We explored its application further for tumor cell tracking in a human liver tumor xenograft mouse model. Tumor xenografts were examined by fluorescence imaging and conventional histological methods. In addition, a method based on DMAHAS release was developed for tumor-specific cytotoxicity analysis. Our study indicated that DMAHAS is a reliable probe for tumor tracking and fluorescence imaging. [ABSTRACT FROM AUTHOR]

Background: Formaldehyde (FA) is a common indoor air pollutant that can cause asthma in people experiencing long-term exposure. While FA and other man-made chemicals contribute to the stimulation of asthma in the general population, the underlying molecular pathogenesis of this relationship is not yet well understood. Objective: To explore FA as an irritant for the onset of asthma and as an adjuvant for the induction of allergy. Methods: In the present study, 40 Wistar rats in five experimental groups were exposed to: (i) saline; (ii) ovalbumin (OVA); (iii) OVA + FA at 417 ppb; (iv) OVA + FA at 2500 ppb; and (v) FA at 2500 ppb. Current and prior occupational exposure limits in China were established at 417 ppb and 2500 ppb, respectively. Gaseous FA was administrated to the animals for 6 h/day before and during OVA immunization or saline treatment. Measured outcomes included in situ lung function analysis, cytokine measurement, and histological changes in the rat lungs. Results: The airway reactivity, lung histological changes, pulmonary interleukin-4 secretion, and eosinophil infiltration in the OVA and FA exposed rats were significantly higher after gaseous FA exposures of 417 and 2500 ppb. While FA exposure alone did not induce significant structural changes to the airway, and the rate of inflammatory cell infiltration was the same as for the control group, pulmonary levels of interferon-γ were significantly elevated in the exposed rats. Conclusions: FA may be an irritant as well as serve as an adjuvant for the onset of asthma or asthma-like symptoms. [ABSTRACT FROM AUTHOR]

In the process of upgrading of bio-oil from the fast pyrolysis of biomass, there occur competitive reactions leading to the formation of heavy fraction, light fraction, and undesired fraction (water, gas, and coke) and simultaneously, the heavy fraction as intermediate product which further react to formation of the latter two fractions. Therefore, a lumping kinetic model, which contains four lumping species and five constants, was proposed to describe the process behavior of bio-oil hydrotreating. By the Simplex in non-linear multi-variable optimization, rate constants at different temperatures are obtained and the frequency factors and activation energies are calculated by using least square method. By using the assumed kinetic model, conversion and yields were calculated, which agree quite well with the experiment values. [ABSTRACT FROM AUTHOR]

The structure of coke from five spent residue hydrotreating catalysts was investigated based on ruthenium ion catalyzed oxidation reaction. The distribution of n-alkyl chains and bridges attached to aromatic carbon of coke on catalysts was quantified. Results showed the concentrations of n-alkyl chains and bridges in coke were declined with the increase of carbon number. The substituential group is methyl mainly, and it had no >C5 alkyl chains in coke. Various isomeric benzenepolycarboxylic acids from oxidated products were identified. Then the condensation mode of some aromatic structure was discussed. The precursor of coke affected the coke structure. Catalysts made coke dehydrogenate to form graphite type aromatic condensate. About 60% of coke was graphite type. [ABSTRACT FROM AUTHOR]

Structure of aromatics, resins, and asphaltenes in petroleum residue was undertaken by using ruthenium ion catalyzed oxidation. The distribution of alkyl side chains and bridges connected to aromatic rings was quantified, and the condensed type of aromatic rings was deduced. The structural changes of fractions in residue during hydrotreating were discussed. The results showed that fractions have abundant alkyl side chains (C1-C27), mainly n-alkyl side chains, attached to aromatic carbons, and polymethylene bridges connected to at least two aromatic ring systems are also present. The molar concentrations of these alkyl groups are declined as the increase of chain length. Cata-condensed, peri-condensed, and biphenyl-type aromatic unit structures coexist in fractions, while the proportion of biphenyl type structure is relatively small. The aromatic structure of aromatics is mostly cata-condensed, while for resins the proportion of cata-condensed and peri-condensed type aromatic structures is comparable, and structure of asphaltene is mostly peri-condensed. The chemical structure of fractions in residue changed due to the increase of hydrotreating degree. The enrichment of large aromatic units made asphaltene have more aromatic structures and higher condensed degree. [ABSTRACT FROM AUTHOR]

One atmosphere residue was hydrotreated (HDT) in a pilot plant at constant conditions. The properties of the HDT products from a series of reactors and their sub-fractions were characterized by H/C, sulfur, nitrogen, carbon residue, nickel, vanadium, and VPO apparent molecular weight. The removal levels of sulfur, nitrogen, carbon residue, nickel, and vanadium were 84.9 m%, 51.4 m%, 62.8 m%, 84.8 m%, and 94.0 m%, respectively. The removal increment of contaminants in reactors was very different during HDT. The ranking of sulfur and nitrogen contents in sub-fractions was asphaltene > resin > aromatic > > saturate; however, the distribution of sulfur in sub-fractions was aromatic > resin > > asphaltene > saturate, while that of nitrogen was resin > > aromatic > asphaltene. Average carbon residue was removed in reactors. Nickel and vanadium were removed mainly in hydrodemetalization reactors. [ABSTRACT FROM AUTHOR]

Using a combination of atomic-resolution high-angle annular dark-field (HAADF) Z-contrast imaging and ab initio calculations, atomic models of clusters 2 nm in diameter and 0.8 nm in height are proposed for the Al-Co-Ni pentagonal quasicrystal. This quasicrystal has 5-fold symmetry (the so-called 5f state) without superstructures, and is one of numerous modifications of the Al-Co-Ni decagonal quasicrystal. HAADF results reveal that the two-dimensional quasi-periodic lattice contains mainly Penrose pentagonal tiling. The centres within the decorated pentagonal tiles, i.e. the so-called pentagonal super-clusters, show structural characteristics having both a satellite-orbit shape and a pentagon-symmetry shape. The proposed atomic models, based directly on the HAADF images, are subjected to ab initio total energy calculations. After relaxation, the calculations demonstrate that the models with 5-fold symmetry are energetically more favourable than those with 10-fold symmetry. [ABSTRACT FROM AUTHOR]

Barbu and Triggiani (Indiana Univ. Math. J. 2004; 53:1443-1494) have proposed a solution of the internal feedback stabilization problem of Navier-Stokes equations with no-slip boundary conditions. They have shown that any unstable steady-state solution can be exponentially stabilized by a finite-dimensional feedback controller with support in an arbitrary open subset of positive measure. The finite dimension of the feedback controller is minimal and is related to the largest algebraic multiplicity of the unstable eigenvalues of the linearized equation. The feedback law is obtained as a solution of a linear-quadratic control problem. In this paper, we formulate a practical algorithm implementation of the proposed stabilization approach, based on the finite element method, and demonstrate its applicability and effectiveness using an example involving the stabilization of two-dimensional Navier-Stokes equations. [ABSTRACT FROM AUTHOR]

Electromagnetic scattering of metallic column covered by double-negative (DNG) metamaterials is simulated with auxiliary differential equation method in Finite-Difference Time-Domain method. Lossy Drude polarization and magnetization models are used to simulate DNG media. Numerical result shows that though the backward scattering of metallic column covered by DNG media decrease, the forward scattering increase. The effects to the backward scattering caused by the variation of DNG media's depth, plasma frequency, damping frequency and incident wave frequency are discussed. [ABSTRACT FROM AUTHOR]