Parameter identification of the fatigue-testing rig

In this paper the dynamic parameter identification of the novel fatigue-testing rig is presented. The applied identification method assumes a priori a simple dynamical model for which parameters are identified through free and forced vibration tests. The rig is comprised of two base excited oscillators providing the dynamic excitation for a fatigue sample and two pneumatic actuators preventing a loss of contact between the oscillators and the sample. The actuators introduce strong nonlinearities. All parameters of the system apart from the pneumatic actuators identified through the free vibration tests using the linear model were in a good agreement with those obtained by the frequency analysis. Two models, a linear and the nonlinear with Coulomb friction, were dynamically interrogated by a random excitation. It was shown that the stiffness coefficient a, increases linearly with the pressure in the pneumatic cylinders, and the viscous damping coefficient b increases quadratically with the air pressure in the pneumatic cylinders. The predicted responses for the linear and nonlinear models correlate well with the experimental data.     

Chimeric protein for selective cell attachment onto cellulosic substrates

We have developed a fusion protein (CBD-LG) incorporating a cellulose-binding domain and an antibody binding domain, protein LG, to provide an adaptor molecule for cell separation with regenerated cellulose hollow fiber arrays. A single hollow fiber cell adhesion assay utilizing a CD34+ cell line, KG1a, was used to investigate whether ligand affinity interactions were strong enough for cell attachment and separation. CBD-LG efficiently captured CD34+ cells labeled with the mouse IgG2a monoclonal antibody MHCD3400. However, it was not possible to bind CD34+ cells labeled with an IgG1 antibody (HPCA-2). The low affinity of HPCA-2 for LG was overcome by secondary antibodies: KG1a cells that were dual labeled with HPCA-2 followed by rat anti-mouse IgG1 adhered inside hollow fibers coated with CBD-LG. Alternatively, immobilized rabbit polyclonal anti-mouse IgG1 captured cells labeled with HPCA-2. The development of an adaptor molecule to display recombinant domains at the surface of hollow fibers will be an effective tool to investigate cellular ligand-receptor interactions, a necessary step in the development of hollow fiber bioreactors for manufacture of human cellular products.     

Dynamic viscosity measurement in non-Newtonian graphite nanofluids

ABSTRACT: : The effective dynamic viscosity was measured in the graphite water-based nanofluids. The shear thinning non-Newtonian behavior is observed in the measurement. On the basis of the best fitting of the experimental data, the viscosity at zero shear rate or at infinite shear rate is determined for each of the fluids. It is found that increases of the particle volume concentration and the holding time period of the nanofluids result in an enhancement of the effective dynamic viscosity. The maximum enhancement of the effective dynamic viscosity at infinite rate of shear is more than 24 times in the nanofluids held for 3 days with the volume concentration of 4% in comparison with the base fluid. A transmission electron microscope is applied to reveal the morphology of aggregated nanoparticles qualitatively. The large and irregular aggregation of the particles is found in the 3-day fluids in the drying samples. The Raman spectra are extended to characterize the D and G peaks of the graphite structure in the nanofluids. The increasing intensity of the D peak indicates the nanoparticle aggregation growing with the higher concentration and the longer holding time of the nanofluids. The experimental results suggest that the increase on effective dynamic viscosity of nanofluids is related to the graphite nanoparticle aggregation in the fluids.     

Yield stress behaviour of metal injection moulding suspensions at elevated temperatures

Yield behaviour of metal injection moulding (MIM) feedstocks was studied using a cone and plate controlled stress rheometer. Four feedstocks consisting of 58 vol % carbonyl iron (with 2 wt % nickel) in different ethylene vinyl acetate (EVA):beeswax ratio binder systems were studied at six temperatures ranging from 130 to 180C. The yield stress was found by extrapolating to zero shear rate of the measured data obtained using a controlled stress rheometer over low shear rate regime. The yield stress, _y, was found to increase with decreasing temperature. An Arrhenius equation was used to relate the dependence of yield stress on temperature and the corresponding activation energy for yield, E _y, can be determined. For a given temperature, feedstocks with higher EVA content exhibited higher _y and E _y. Moreover, the effect of temperature on yield stress was found to be greater for feedstocks with higher EVA content.     

Accelerated start-up and enhanced granulation in upflow anaerobic sludge blanket reactors

In the present study, the effects of a cationic polymer on reactor start-up and granule development were evaluated. A control reactor R1 was operated without adding polymer, while the other five reactors designated R2, R3, R4, R5 and R6 were operated with different polymer concentrations of 20, 40, 80, 160 and 320 mg/L, respectively. Experimental results demonstrated that adding the polymer at a concentration of 80 mg/L markedly accelerated the start-up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4 g COD/L.d was reduced by approximately 50% in R4 as compared with the control reactor. The same reactor with 80 mg/L polymer was able to achieve an OLR of 12 g COD/L.d after 59 days of operation, while R1, R2, R3, R5 and R6 achieved the same loading rate at much longer period of 104, 80, 69, 63 and 69 days, respectively. Comparing with the control reactor, the start-up time of R4 was shortened markedly by about 43% at this OLR, while other reactors also recorded varying degree of shortening. Monitoring on granule development showed that the granule formation was accelerated by 30% from the use of the appropriate dosage of polymer. Subsequent granules characterization indicated that the granules developed in R4 with 80 mg/L polymer exhibited the best settleability, strength and methanogenic activity at all OLRs. The organic loading capacities of reactors were also increased by the polymer addition. The maximum organic loading of the control reactor was 24 g COD/L.d, while the polymer-assisted reactor added with 80 mg/L polymer attained a markedly increased organic loading of 40 g COD/L.d. The laboratory results obtained demonstrated that adding the cationic polymer could result in shortening of start-up time and enhancement of granulation, which in turn lead to improvement in organics removal efficiency and loading capacity of the UASB system.     

Enhancing the mechanical and barrier properties of chitosan/graphene oxide composite films using trisodium citrate and sodium tripolyphosphate crosslinkers

This study investigated the effect of ionic crosslinking on the mechanical, barrier, and optical properties of chitosan (CS) and CS/graphene oxide (CSGO) composite films using trisodium citrate (CIT) and sodium tripolyphosphate (TPP) solutions of different concentrations (0.5, 1.0. 2.0, and 3.0% w/v). Successful crosslinking was confirmed by Fourier-transform infrared spectroscopy. The hydrophilicity and light transmittance decreased significantly (p < 0.05) with the increase in concentration of both crosslinking agents. The CS films crosslinked with 3.0% w/v TPP exhibited significant (p < 0.05) improvements in barrier properties, achieving a 51% decrease of water vapor permeability and 59% decrease in oxygen permeability, in comparison to neat CS film. In addition, TPP-crosslinked CSGO films experienced an 82% and 42% improvement in tensile strength and elongation at break, respectively. Overall, crosslinked CS and CSGO films possess significantly improved properties and have great potential to be further studied as food packaging materials.     

Porous Quaternary Al0.1In0.1Ga0.8N Film Formation via Photoelectrochemical Etching in HF:C2H5OH Electrolyte

Pore formation in AlInGaN films using photoelectrochemical etching in different volume ratios of hydrofluoric acid:ethanol solution (1:1, 1:2, 1:3, and 1:4) has been investigated structurally, morphologically, and optically. A significant increase in root mean square roughness and photoluminescence intensity in AlInGaN film etched in 1:1 solution has yielded the highest pore density and the largest average pore size in the film. Moreover, the acquisition of the lowest total dislocation density as well as the largest in‐plane biaxial stress relaxation in the film suggested potential use of the porous film as a template to grow subsequent layers for development of light‐emitting diodes.     

Age, time of testing, and proactive interference.

A four-list version of a release from proactive interference paradigm was used to assess the degree to which older (aged 58-78 yrs) and younger adults (aged 18-32 yrs) tested at optimal and nonoptimal times of day are vulnerable to interference effects in memory, effects that may increase at nonoptimal times. Morning type older adults and Evening type younger adults were tested either early in the morning or late in the afternoon. Standard buildup and release effects were shown for all age groups except for older adults tested in the afternoon; they failed to show release. Recall and intrusion data suggested that older adults are more vulnerable to proactive interference than younger adults and that for older adults at least, interference effects are heightened at nonoptimal times of day. The data are discussed in terms of an inhibitory model of control over the contents of working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)