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Propagation of a H2-added strained laminar CH4/air flame in a rich-to-lean stratified mixture is numerically studied. The back-support effect, which is known to enhance the consumption speed of a flame propagating into a leaner mixture compared to that into a homogeneous mixture, is evaluated. A new method is devised to characterize unsteady reactant-to-reactant counterflow flames under transiently decreasing equivalence ratio, in order to elucidate the influence of flow strain on the back-support effect. In contrast to the conventional reactant-to-product configurations, the current configuration is more relevant to unsteady stratified flames back-supported by their own combustion products. Moreover, since H2 distribution downstream of the flame is known to play a crucial role in back-supported CH4/air flames, the influence of H2 addition in the upstream mixture is examined. The results suggest that a larger strain rate leads to a larger equivalence ratio gradient at the reaction zone through increased flow divergence, which amplifies the back-support. Meanwhile, since H2 addition in the upstream mixture does not affect the downstream H2 content, the relative increase in the consumption speed, i.e. the back-support, is suppressed with larger H2 addition. Especially, when the upstream H2 content decreases with the equivalence ratio, the H2 preferentially diffuses toward the unburned gas, which mitigates H2 accumulation in the preheat zone and further weakens the back-support.

This research observes hydrogen production from water using biophotocatalyst from activated carbon (AC) and Clitoria ternatea powder (CTP). AC is assembled by defective graphene layers and CTP by aromatic ring with hydroxyl groups. AC and CTP have been tested individually and in combination at irradiation light wave length from 600 to 400 nm. The results show that the same wave length of the absorbance peak of AC and CTP is due to their aromatic ring. The very low absorbance intensity in AC is due to its very low effective surface contact and the negative charges around the pores of AC attract hydrogen proton that hinders hydrogen production. The hydroxyl groups in CTP energize delocalized electron in aromatic ring by attracting the electron to transit them, therefore, absorb high light intensity. When they are combined, the photo catalyst performance in hydrogen production increase almost four fold. This is due to attracted force from the charge in the pores of AC to hydroxyl groups in CTP that further energizes delocalized electron in aromatic ring of CTP, thereby boosts the photocatalyst activity. When the wave length of irradiation light is the same as the catalyst light absorbance wave length, the hydrogen production is the highest.

Background:Intermediate Filaments (IFs) are major constituents of the cytoskeletal systems in animal cells.Objective:To gain insights into the structure-function relationship of invertebrate cytoplasmic IF proteins, we characterized an IF protein from the platyhelminth, Dugesia japonica, termed Dif-1.Method:cDNA cloning, in situ hybridization, immunohistochemical analysis, and IF assembly experiments in vitro using recombinant Dif-1, were performed for protein characterization.Results:The structure deduced from the cDNA sequence showed that Djf-1 comprises 568 amino acids and has a tripartite domain structure (N-terminal head, central rod, and C-terminal tail) that is characteristic of IF proteins. Similar to nuclear IF lamins, Djf-1 contains an extra 42 residues in the coil 1b subdomain of the rod domain that is absent from vertebrate cytoplasmic IF proteins and a nuclear lamin-homology segment of approximately 105 residues in the tail domain; however, it contains no nuclear localization signal. In situ hybridization analysis showed that Djf-1 mRNA is specifically expressed in cells located within the marginal region encircling the worm body. Immunohistochemical analysis showed that Djf-1 protein forms cytoplasmic IFs located close to the microvilli of the cells. In vitro IF assembly experiments using recombinant proteins showed that Djf-1 alone polymerizes into IFs. Deletion of the extra 42 residues in the coil 1b subdomain resulted in the failure of IF formation.Conclusions:Together with data from other histological studies, our results suggest that Djf- 1 is expressed specifically in anchor cells within the glandular adhesive organs of the worm and that Djf-1 IFs may play a role in protecting the cells from mechanical stress.

A novel hybrid material, which is an enzyme/inorganic nanosheet complex coated by molecularly imprinted polymer (MIP), was developed, and applied to colorimetric quercetin assay. First, an enzyme/inorganic nanosheet complex was prepared from horseradish peroxidase (HRP) enzyme and titanate nanosheet (TiOx), using electrostatic interactions between them in acetate buffer. In the next place, dopamine self-polymerization was performed in the presence of HRP/TiOx complex with quercetin as a template, to prepare MIP membrane onto the HRP/TiOx complex. After washing process, a new hybrid material, MIP-coated HRP/TiOx complex (MIP-HT) was obtained. MIP-HT adsorbed quercetin efficiently, compared with NIP-HT that is an HRP/TiOx complex coated with non-imprinted polydopamine. MIP-HT showed enzymatic activity for an oxidation reaction of guaiacol, which is a chromogenic substrate of HRP, whereas the enzymatic activity of NIP-HT was significantly suppressed. The amount of brown product, formed by the color reaction, reduced owing to the presence of quercetin in sample solution, and a good liner relationship was observed between the concentration of quercetin and the increment of absorbance at 470 nm. The investigation using several biomolecules indicates that MIP-HT has the ability to detect quercetin and its analogues with selectivity. Therefore, MIP-HT shows great promise as a new and attractive material for use in colorimetric assay of quercetin or quercetin analogues.

The response of laminar methane/air counterflow premixed flames under sinusoidal equivalence ratio oscillation was investigated numerically. The timescales of the oscillation were chosen to be sufficiently longer than the flame timescale so that the flame responds quasi-steadily. The response of periodically stratified flame (SF) with a detailed reaction mechanism exhibited the “back-support” effect, in that the consumption speed Sc response deviated increasingly from Sc of steady homogeneous flames (HFs) at higher oscillation frequencies. It was shown that even when the imposed oscillation timescale is much longer than the flame timescale, the flame response can still be delayed under a sufficiently large equivalence ratio gradient. Subsequently, the above results were compared with those obtained with a global four-step mechanism that omits back-diffusion radicals into the reaction zone. As a result, SFs with the global mechanism displayed a much smaller back-support effect in both lean and rich mixtures. Further analysis with modified diffusion coefficients revealed the dominant roles of H2 and radical species diffusion in inducing the back-support effect. Contrary to the previous findings, variations in burned gas temperature were found to play a negligible role in modifying Sc. Additionally, the hysteresis of the back-support effect under periodical stratification was found to be more prominent on the richer side because of the presence of a larger H2 pool.

Chlorophyll-a (Chl-a) discolors when it is exposed to light, and such discoloration decreases food quality. To elucidate the discoloration mechanism of Chl-a, we determined discoloration rate in different Chl-a chemical species and assessed the size of Chl-a aggregates in mixed aqueous solutions of methanol and ethanol. Chl-a existed as monomer, J-aggregate, and random aggregate in solutions with different alcohol concentrations. The predominant species depended on the alcohol concentration. Monomeric Chl-a and J-aggregates discolored quickly, whereas random aggregates discolored slowly. Particle sizes of J-aggregates were 319 and 2305 nm in diameter in aqueous solutions of methanol and ethanol, respectively. The sizes of random aggregates were 51 and 79 nm in 10% (v/v) aqueous solutions of methanol and ethanol, respectively. The size of Chl-a aggregates positively correlated with the rate of Chl-a discoloration under UV light. Based on the results obtained, we propose a mechanism of Chl-a discoloration.

The effect of Rh3+ catalyst on the combustion of the Crude Vegetable Oil droplet, namely coconut, jatropha, and sunflower oil has been studied experimentally at atmospheric pressure and room temperature. The oil droplets contain multi-component elements that are saturated fatty acid, monounsaturated fatty acid, polyunsaturated fatty acid, and glycerol. Results demonstrated that the catalyst has a stronger influence on crude coconut oil (CCO) and crude sunflower seed oil (CSFO) polar compounds during combustion, indicated by a greater enlargement of their triglyceride chains relative to those in crude jatropha oil (CJO). The changes in triglyceride geometry were identified as the cause of the distinguishing CVO droplet combustion characteristics. During the heating process preceding ignition, internal evaporation occurs with the appearance of bubbles trapped in oil droplets, and it appears that the diameter of the CJO droplet is greater than that of CCO and CSFO. This result suggests that the non-polar CJO compounds are more saturated, requiring additional heat for evaporation and ignition. The results also show that the catalyst makes multi-step burning droplets becomes shorter in one stage with the highest burning temperature. This proves that the catalyst does not only enlarge the triglyceride geometry but also excites the electrons due to hydrogen atom attraction as well.

Intermediate Filaments (IFs) are major constituents of the cytoskeletal systems in animal cells.To gain insights into the structure-function relationship of invertebrate cytoplasmic IF proteins, we characterized an IF protein from the platyhelminth, Dugesia japonica, termed Dif-1.cDNA cloning, in situ hybridization, immunohistochemical analysis, and IF assembly experiments in vitro using recombinant Dif-1, were performed for protein characterization.The structure deduced from the cDNA sequence showed that Djf-1 comprises 568 amino acids and has a tripartite domain structure (N-terminal head, central rod, and C-terminal tail) that is characteristic of IF proteins. Similar to nuclear IF lamins, Djf-1 contains an extra 42 residues in the coil 1b subdomain of the rod domain that is absent from vertebrate cytoplasmic IF proteins and a nuclear lamin-homology segment of approximately 105 residues in the tail domain; however, it contains no nuclear localization signal. In situ hybridization analysis showed that Djf-1 mRNA is specifically expressed in cells located within the marginal region encircling the worm body. Immunohistochemical analysis showed that Djf-1 protein forms cytoplasmic IFs located close to the microvilli of the cells. In vitro IF assembly experiments using recombinant proteins showed that Djf-1 alone polymerizes into IFs. Deletion of the extra 42 residues in the coil 1b subdomain resulted in the failure of IF formation.Together with data from other histological studies, our results suggest that Djf- 1 is expressed specifically in anchor cells within the glandular adhesive organs of the worm and that Djf-1 IFs may play a role in protecting the cells from mechanical stress.

The dynamics of a laminar premixed stagnating flame subjected to simultaneous velocity and equivalence ratio oscillations are investigated experimentally. A flame of premixed methane and air is formed in a wall-stagnating flow. The oscillations of velocity and equivalence ratio are imposed independently by two sets of dual cylinder–piston oscillators. To impose the equivalence ratio oscillation, methane/air mixtures with equivalence ratios of $$\phi =1.0$$ and $$0.4$$ are supplied to different cylinder–piston units. The pistons move in anti-phase and create a sinusoidal equivalence ratio oscillation while keeping the volume flow rate constant. To impose the velocity oscillation, a mixture with $$\phi =0.7$$ is supplied to the single unit of another oscillator. The phase difference between the two oscillations is set by changing the relative position of the pulley teeth of the two oscillators. The oscillator frequency is varied between 2 and 20 Hz, meaning that the oscillation wavelengths are much longer than the flame thickness. When frequencies of the velocity and equivalence ratio fluctuations are in a quasi-steady state condition, the flame motion is affected independently by velocity oscillation and equivalence ratio oscillation and the linear-superposition assumption can be applied. When the velocity and equivalence ratio oscillation frequencies are increased and exceed the transition frequency from the quasi-steady state to unsteady state, the flame motion gradually deviates from linear-superposition assumption. This is due to the variations in the unsteady molecular diffusion and the back-support effect.

The alternative fuels were developed from a blended fuel with crude jatropha oil (CJO) and rhodium sulfate as a homogeneous combustion catalyst. In this study, the performances of blended fuel droplets were investigated experimentally under normal gravity conditions. Combustion characteristics were observed by igniting droplets at the thermocouple junction, and the droplet combustion was observed using a high-speed camera. To this end, understanding how the molecular structure (bonding and angular properties of triglyceride carbon chains) of the fuel affects the combustion characteristics is crucial. The results showed that CJO had 53 rotatable and 111 nonrotatable bonds. This makes CJO more rigid and nonpolar. The interaction of the catalyst with triglycerides changes the molecular chain bond angle so that the atoms get extra space to move, thereby increasing the electron mobility. This makes the fuel molecule more reactive so that the viscosity and flash point are reduced and the fuel is easily ignited. Moreover, the results also showed that the catalyst improved combustion performance, where droplet ignition times were shorter at higher temperatures, and fuel droplets had higher burning rates and combustion temperatures.

Effects of velocity and fuel concentration oscillations on premixed flames are discussed. Methane/air premixed flame is formed in a wall stagnating flow. The velocity oscillation is imposed to the flow with 𝛷=0.7 by an oscillator with single cylinder-piston unit. The equivalence ratio oscillation is imposed by an oscillator with two cylinder-piston units. The methane/air mixture with the equivalence ratio 𝛷=1.0 is supplied to one unit and that 𝛷=0.4 is supplied to the other unit. Pistons move with 180 degree phase difference which creates a sinusoidal equivalence ratio oscillation keeping the volume flow rate constant. Two oscillators are driven by a single DC motor to ensure complete synchronization. Phase difference between velocity oscillation and equivalence ratio oscillation is set by changing the relative position of pulley teeth of two oscillators. The oscillator frequency varies between 2 Hz and 20 Hz, which means that the oscillation wavelengths are much longer than the flame thickness. The flame motion was recorded by a high-speed video camera. Results showed that the amplitude of the flame motion was a linear superposition of the flame motion by the velocity oscillation and the equivalence ratio oscillation, indicating that each oscillation affects the flame motion independently.Effects of velocity and fuel concentration oscillations on premixed flames are discussed. Methane/air premixed flame is formed in a wall stagnating flow. The velocity oscillation is imposed to the flow with 𝛷=0.7 by an oscillator with single cylinder-piston unit. The equivalence ratio oscillation is imposed by an oscillator with two cylinder-piston units. The methane/air mixture with the equivalence ratio 𝛷=1.0 is supplied to one unit and that 𝛷=0.4 is supplied to the other unit. Pistons move with 180 degree phase difference which creates a sinusoidal equivalence ratio oscillation keeping the volume flow rate constant. Two oscillators are driven by a single DC motor to ensure complete synchronization. Phase difference between velocity oscillation and equivalence ratio oscillation is set by changing the relative position of pulley teeth of two oscillators. The oscillator frequency varies between 2 Hz and 20 Hz, which means that the oscillation wavelengths are much longer than the flame thickness. The flame...

The hydrogen permeation with a flat sheet Pd/Ag membrane for mixture of hydrogen and carbon dioxide was investigated experimentally. A flat sheet, dense 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and diameter of 0.02m was used. The membrane temperature, total upstream pressure and inlet H2 mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.089-0.62mol.s-1.m-2. When the mean mole flux is increased, hydrogen permeation flux increases, which is supposed due to the effect of flow velocity. In addition, the analytical result based on Sieverts’ equation with the effect of permeation is found to be very close with the experimentally obtained hydrogen permeation flux. For permeation with H2:CO2 mixture, future work is necessary to investigate the variation in permeation flux with time.

The variation in hydrogen concentration distribution on Pd/Ag membrane surface for permeation with H2/N2 mixture was investigated numerically, by varying the diameter of the mixture inlet. A 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and effective surface area of 3.14x10-4m2 was considered. The membrane temperature, total upstream pressure, and inlet H2 mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.19-0.95 mol.s-1.m-2. The hydrogen concentration distribution was investigated for various ratios of inlet radius to membrane radius (0.22:1, 0.50:1 and 0.75:1). It is found that hydrogen permeation flux obtained from various hydrogen concentration distributions are almost same, and quantitatively fit with analytical result based on the Sieverts’ equation with the effect of H2 permeation.

The permeation characteristic of a flat sheet Pd/Ag membrane was investigated experimentally by using pure hydrogen. A 77wt.%Pd/23wt.%Ag membrane with 25μm thickness and 0.02m diameter was used. The hydrogen permeation mole flux was investigated under various reference membrane temperatures (423-723K), for upstream pressures of 0.21-0.29MPa, and feed flow rate of 1.39x10-4mol/s. In all cases, the downstream pressure was set at atmospheric. Experimental results demonstrate the linear relationship between the hydrogen permeation flux and difference in square root of hydrogen partial pressure between the upstream side and downstream side, regardless of reference temperatures. This indicates the compatibility of the Pd/Ag membrane used in the present study with Sieverts’ Law. At sufficiently low temperature level, the hydrogen permeation flux is found to be very sensitive with the changes in the temperature.

The estimation of hydrogen permeation mole flux was performed by previously introduced theoretical equation which considers the decrease in H2 concentration at the membrane surface, and was compared with experimental result, for various hydrogen mixtures with different inlet H2 mole fractions and species. A flat sheet 77 wt.% Pd/23 wt.% Ag purification membrane with effective surface area of 3.14 × 10−4 m2 was used. For H2:N2 mixture, the comparison was performed under various feed flow rates (2.78 × 10−5–2.50 × 10−4 mol/s), for inlet H2 mole fraction of 0.70–0.80, at reference membrane temperature of 623 K and total upstream pressure of 0.25 MPa. Then, nitrogen was subsequently replaced with argon (Ar), helium (He) and carbon dioxide (CO2) to investigate the applicability of the estimation method for various H2 mixtures with different species. The results demonstrate that the effect of H2 permeation itself plays a significant role for permeation with H2 mixture, which induces the phenomenon of concentration polarization. Overall, the introduced method is able to estimate H2 permeation mole flux for H2 mixture, both qualitatively and quantitatively, regardless of inlet H2 mole fraction and species.

Luminescent europium-doped layered titanates (Eu-TiOx) were synthesized and complexed with horseradish peroxidase (HRP) and glucose oxidase (GOx). The emission of a resultant Eu-TiOx/HRP/GOx complex decreased upon the addition of glucose in the presence of guaiacol. The emission decrease was dependent on the concentrations of glucose, and the detection limit for glucose was 3.1 μM. The proposed system would be promising as a new detection method for glucose.

Effect of transient variation in the fraction of components in the multi-component fuels on the characteristics of a Bunsen-type burner has been investigated experimentally. Methane/ethane/propane three-component fuel, methane/ethane two-component fuel and methane/propane two-component fuel were used. The flame motion under the linear transition from one fuel mixture to another was examined. The transition time was varied from 1 s to 10 s, keeping the flow velocity and the equivalence ratio constant at 0.8 m/s and 0.85 respectively. The variation in the flame height was measured, using high speed video camera at 125 fps. Experimental results showed the overshoot of the flame height in an upward or downward direction during the transition. The magnitude of the overshoot was larger for shorter transition time and for larger difference of volume fraction of fuel components. The difference in diffusion coefficient of each fuel is supposed to play an important role for the overshoot.

The combustion behavior of a methane hydrate sphere under normal gravity is experimentally investigated. The initial diameter of the sphere is 20 mm. Variation in temperature at the center of the sphere (T c) is measured with a K-type thermocouple at ignition temperatures (T c,i) from 193 to 253 K at 20 K intervals. Variation in the near-surface temperature of the sphere (T s) is measured at ignition temperatures (T s,i) from 233 to 263 K at 10 K intervals. Two combustion phases are observed. When the hydrate is ignited, a stable flame envelope is formed around the sphere (phase 1). In phase 1, the surface of the sphere is dry. After a few seconds, water formed by dissociation of the methane hydrate appears on the surface and methane bubbles are formed by methane ejected from inside the sphere (phase 2), thus destabilizing the flame and causing local extinction. Methane bubbles move down along the surface and merge into a large methane bubble at the bottom of the sphere. This bubble bursts, releasing methane to form a temporary flame, and the water drops from the hydrate sphere. Water on the surface is cooled by the hydrate inside, and an ice shell confines the methane gas that dissociated inside the sphere. Because the dissociation occurs continuously inside the hydrate, the inner pressure gradually increases and at some instant, the ice cracks and methane gas is ejected from the cracks, which results in a micro-explosion with a flame. In phase 1, the surface temperature is below the freezing point of water, and so the surface remains dry and a stable flame envelope is formed; in phase 2, the surface temperature is above the freezing point, and so water appears on the surface. When the temperature at the center of the sphere is lower (193, 213, or 233 K), some methane hydrate remains even after flame extinction because heat transfer from the flame decreases in phase 2 as a result of local extinction. The diameter of the sphere decreases during combustion in accordance with the d-square law, which indicates that the heat of dissociation is supplied by the flame and methane is supplied by the dissociation of methane hydrate in the sphere, as in single-droplet combustion.

The effect of the equivalence ratio oscillation on a premixed laminar CH4/air flame motion was studied experimentally with equivalence ratio oscillation frequencies of 2 to 15 Hz at lean equivalence ratio using stagnation flow field burner. Novel oscillator does the oscillation conditions and turbulence reduction method is used to suppress the velocity perturbation. The flame position variations at 2, 5, 10 and 15 Hz oscillation frequencies were significantly small when the amplitude of the equivalence ratio oscillation was zero. On the other hand, increase in amplitudes of the equivalence ratio oscillation increased the flame position variation significantly. The flame moved in sinusoidal shape and it can be clearly seen that the flame movement’s amplitude was proportional to the amplitudes of the equivalence ratio variations. This result showed that the velocity perturbation is significantly suppressed by turbulence reduction method in the examination range.

The angiotensin-I converting enzyme (ACE) inhibitory activity of the milk fermented with Lactococcus lactis subsp. lactis NBRC 12007 and Saccharomyces cerevisiae K7 in monoculture and co-culture was evaluated. Bovine full-fat milk was fermented with each strain in monoculture and co-culture at 30 oC for 72 h, and the in vitro ACE inhibitory activity (%) of each milk sample was determined by a fluorogenic assay using H-(2)Abz-Acp(6)-Ala-Phe(4-NO2)-Leu-OH as the substrate. The ACE inhibitory percentages of the milk samples fermented with L. lactis subsp. lactis NBRC 12007 and S. cerevisiae K7 monocultures and the co-culture was 33, 27 and 25 %, respectively, which varied significantly (p L. lactis subsp. lactis NBRC 12007, S. cerevisiae K7 and the co-culture, respectively. The highest ACE-inhibitory activity (47 %) was observed in fraction-2 of the milk fermented with L. lactis subsp. lactis NBRC 12007. The results concluded that the two strains tested were able to hydrolyze milk proteins into ACE-inhibitory peptides in order to produce fermented milk products with ACE-inhibitory activity, both in monoculture and co-culture. Therefore, it can be suggested that these strains can be successfully utilized in the dairy industry in manufacturing fermented milk products with ACE-inhibitory activity as a dietary supplement and/or as an alternative approach for antihypertensive medication. J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 141-151