Decrease In Decay Rate Research Articles

Second-Order Sidebands and Group Delays in Coupled Optomechanical Cavity System with a Cubic Nonlinear Harmonic Oscillator

The generation of second-order sidebands and its associated group delay is an important subject in optical storage and switch. In this work, the efficiency of second-order sideband generation in a coupled optomechanical cavity system with a cubic nonlinear harmonic oscillator is theoretically investigated. It is found that the efficiency of second-order sideband generation can be effectively enhanced with the decrease in decay rate of optomechanical cavity, the increase in coupling strength between two cavities and the power of probe field. The slow light effect (i.e., positive group delay) is also observed in the proposed optomechanical cavity system, and can be controlled with the power of control field.

A Systematic Study of Two-Neutrino Double Electron Capture

In this paper, we update the phase-space factors for all two-neutrino double electron capture processes. The Dirac–Hartree–Fock–Slater self-consistent method is employed to describe the bound states of captured electrons, enabling a more realistic treatment of atomic screening and more precise binding energies of the captured electrons compared to previous investigations. Additionally, we consider all s-wave electrons available for capture, expanding beyond the K and L1 orbitals considered in prior studies. For light atoms, the increase associated with additional captures compensates for the decrease in decay rate caused by the more precise atomic screening. However, for medium and heavy atoms, an increase in the decay rate, up to 10% for the heaviest atoms, is observed due to the combination of these two effects. In the systematic analysis, we also include capture fractions for the first few dominant partial captures. Our precise model enables a close examination of low Q-value double electron capture in 152Gd, 164Er, and 242Cm, where partial KK captures are energetically forbidden. Finally, with the updated phase-space values, we recalculate the effective nuclear matrix elements and compare their spread with those associated with 2νβ−β− decay.

Efficiency assessment of underground biomethanation with hydrogen and carbon dioxide in depleted gas reservoirs: A biogeochemical simulation

Underground biomethanation, which converts hydrogen and carbon dioxide to methane with the catalysis of methanogens in geological formations, has great potential for carbon dioxide utilization and sequestration, renewable natural gas production, and large-scale energy storage. However, the efficient conversion of hydrogen and carbon dioxide in a complex reservoir environment has not been explored. To address this issue, a novel biogeochemical model is developed for underground biomethanation that considers reservoir environment factors (e.g. pH, temperature, and salinity) and integrated into PHREEQC software. The biogeochemical model is validated with a laboratory experiment and utilized to investigate the effects of reservoir parameters and injection parameters on biomethanation efficiency in depleted gas reservoirs. Results show that the biomethanation efficiency is 94.2% after 360 days in both sandstone and carbonate reservoirs. Underground biomethanation can be completed in 30 days if initial biomass and optimum specific growth rate increase and decay rate decreases. Additionally, the optimal ratio of injected hydrogen and carbon dioxide for biomethanation is greater than 4:1 and increases with total pressure if it is above 70 atm. To improve the biomethanation efficiency, this study suggests utilizing geothermal energy and pre-injecting highly active methanogens cultured on the ground before mixed gas injection.

Influence of Post‐Treatment Temperature on the Stability and Swelling Behavior of Casein Microparticles

AbstractThis study investigates the influence of exposure time and post‐treatment temperature on the stability and swelling of casein microparticles prepared by depletion flocculation and film drying. Stability experiments with sodium dodecyl sulfate at 20 °C show that particles become more stable with higher post‐treatment temperature and longer exposure times. The two‐step decrease in decay rates in each case indicates a stable intermediate state structurally different from untreated and more strongly treated microparticles. The swelling curves of microparticles also show differences in three temperature ranges at 120 min exposure times each, which is analyzed with dynamic swelling models. At temperatures T ≤ 50 °C, the casein microparticles swell and decompose in a typical two‐step process. For post‐treatments in the temperature range between T = 60 and 70 °C, the swelling curves change their shape toward limited swelling to an equilibrium swelling value. The swelling curves of microparticles treated with temperatures at 80 and 90 °C show a typical overshooting, which can be analyzed with an adapted parallel swelling model and attributed to an elastic network of newly formed bonds.

Long-term study on wood degradation in urban soil-water systems - implications for service life of historic foundation piles

Many historic buildings in urban environments are raised on wooden foundations, and due to microbial degradation their service life varies greatly. This is one of the first field experiments in urban environments where wood decay is studied on proxy samples and related to ongoing processes in historic foundation piles. Here 90 proxy samples are exposed at 8 urban sites for 6, 12, and 18 months in the centre of Gothenburg. Development of microbial decay is followed in dipwells adjacent to well-studied historic piles. Analyses by light microscopy show that decay took place at all sites. Erosion bacteria were the sole degrader of wood at ¾ of the sites, both at groundwater level and at pile head level, indicating near anaerobic conditions in the soil pore water. At the two remaining sites, soft rot was also active. Decay increased over time and results demonstrate a significant correlation between depth of exposure below groundwater level and decrease in decay rates. Decay intensity varied between the sites, indicating that other site-specific conditions affect microbial activity. Redox and oxygen measurements did not show any correlation to observed decay intensity in proxy samples. Advise to stakeholders and for future studies are given.

Study on temperature decay characteristics of fire smoke backflow layer in tunnels with wide-shallow cross-section

The temperature distribution characteristics in tunnel fire scenarios are not only crucial for evaluating the hot damage of tunnel structure, but also pivotal fundation to study the smoke kinetic characteristics. In the present work, the scaled-model tests and the CFD simulations were adopted to investigate the effects of aspect ratio, longitudinal ventilation velocity and fire heat release rate on smoke temperature decay characteristics at both transverse and longitudinal directions in tunnel fires. Results indicate that: Tunnel aspect ratio has a significant influence on smoke temperature rate at both transverse and longitudinal directions. The increase of aspect ratio will increase the contact area between the smoke layer and the ceiling, enhancing the heat loss of the smoke backflow layer. As a result, smoke temperature decays faster in a wide-shallow cross-section tunnel. The longitudinal temperature decay rate in the wide-shallow tunnel (AR = 9.3) is almost eight times as large as that in the normal tunnel (AR = 1.1). The increase of fire heat release rate will reduce the smoke temperature decay rate at both transverse and longitudinal direction; As the ventilation velocity increases, the longitudinal temperature decay rate increases while the transverse temperature decay rate decreases. The definition of smoke backflow ratio was proposed to establish the fire smoke temperature decay model of the smoke backflow layer, which considers the effects of aspect ratio, longitudinal ventilation velocity and fire heat release rate. By comparing the test results in previous research work, the new model shows relatively good applicability in the full-scaled tunnel and is valid for a wide range of testing conditions.

Improvement of antifungal activity of a culture filtrate of endophytic Bacillus amyloliquefaciens isolated from kiwifruit and its effect on postharvest quality of kiwifruit.

This study reports the optimization of culture conditions and medium components of M9, an endophytic strain of Bacillus amyloliquefaciens, which we had previously isolated from kiwifruit, and evaluation of its effect on kiwifruit postharvest protection against soft rot. The method of one-factor-at-a-time was used to determine the optimum culture conditions, and response surface methodology was applied to optimize the medium constituents. After optimization, a high rate of antifungal activity (73.12% decrease in decay rate) by M9 culture filtrate against the soft rot fungal pathogen, Botryosphaeria dothidea, was obtained. Compared with the initial culture conditions, the antifungal activity of M9 culture filtrate was increased by 19.5%. Furthermore, a postharvest storage experiment on kiwifruit showed that M9 culture filtrate could maintain the quality of stored kiwifruit, delay fruit senescence, and significantly enhance the storability of kiwifruit. Using liquid chromatography-mass spectrometry, we found that the antifungal activity of M9 was associated with the presence of the C12-surfactin A lipopeptide. PRACTICAL APPLICATIONS: Soft rot caused by Botryosphaeria dothidea is one of the most important diseases of kiwifruit, causing postharvest fruit rot. The disease progresses rapidly and is difficult to control, posing a great threat to the kiwifruit industry. In this study, the culture conditions and medium composition for culture of the strain M9 (kiwifruit endophytic Bacillus amyloliquefaciens) were optimized to maximize the inhibition of B. dothidea. A postharvest storage experiment showed that M9 culture filtrate could improve the disease resistance of kiwifruits, delay the senescence of the fruits, and maintain the quality of kiwifruit during storage. Because M9 is a natural endophyte of kiwifruit, the strategy used in this study was both effective and safe. This work will contribute to the exploitation of B. amyloliquefaciens in controlling the pathogens of kiwifruit and the development of safer and more advanced strategies for the postharvest protection of kiwifruits.

The effect of clothing on decomposition and vertebrate scavengers in cooler months of the temperate southwestern Cape, South Africa

With research providing conflicting results from different habitats across the globe, the effect of clothing on decomposition is unclear; some studies indicate clothing increases decomposition rate by facilitating increased insect activity, and others conclude clothing prolongs the decay process. In South Africa, such research is lacking, with no data for the Western Cape Province, which suffers from a high murder rate with many unclaimed, unidentified bodies. Improving post-mortem interval (PMI) estimates will increase chances of correct forensic identification of decedents by narrowing the search window for police. Since no current PMI estimation method accounts for the possible influence of clothing, this study was designed to examine the effect of seasonally appropriate common clothing on decomposition rate in the thicketed Cape Flats Dune Strandveld, Cape Town, a forensically significant region. Four ∼60 kg domestic pig carcasses (Sus scrofa domesticus) were used as proxies for human decomposition, two were clothed and two unclothed. The clothing, altered by a seamstress to ensure an appropriate fit, caused a notable decrease in decay rate in this initial sample. Daily weight loss was used as a quantitative measure of decomposition progression, as the clothing prevented the use of visual decomposition scoring systems. Weight loss was closely associated with scavenging activity by the Cape grey mongoose (Galerella pulverulenta), with a clear scavenger preference for unclothed carcasses. This suggests that the effect of clothing on decomposition may be better assessed in this environment by examining how scavengers interact with only a single clothed carcass.

Post-peak roughness degradation model based on Barton-Bandis criterion for rock joint

Based on the non-linear shear behaviour obtained by many researchers’ direct shear test, an exponential degradation model about the joint roughness is introduced into Barton-Bandis shear strength criterion to describe the non-linear post-peak shear behaviour. In the degradation model, the joint roughness coefficient (JRC) gradually decreases with the shear displacement to account for asperity degradation during shear process, and the decay rate decreases. Finally the JRC falls to a constant value that corresponds to the residual shear resistance of the joint and the decay rate decreases to zero. At last, the model is used to fit experimental data for different materials of joints, and the high fitting accuracy shows its validity.

Extraction of Model Parameters for Reactive Solute Transport

Rock material is common in the construction of hydraulic structures. In the present study, to the aim is to examine the reactive solute relationships for transport and degradation processes through the rockfill media. By applying the analytical solution of reactive transport, the 1st to 3rd theoretical temporal moments have been extracted, consequently by applying two methods of curve fitting and temporal moment matching, the coefficients of dispersion and degradation have been exploited. Two rock diameter, two operating discharges and five instantly injection mass have been used as the variables of experiments. The EC sensors with operation software were installed inside the rockfill media and then the experimental breakthrough curves with intervals of 4 seconds have been extracted. It is concluded that both methods are suitable for application of transport and degradation processes inside the media. It was found that by increasing inflow discharges, pore velocity, and media diameters the dispersion coefficient decreases and with a decrease in media diameter or with increase in injection mass the decay rate decreases. The sensitivity analysis on the derived moment equation and also skewness coefficient equation indicated that the velocity and degradation are the most and less effective parameters on the moment equations respectively.

Charge coupling behavior of double-layer oil-paper insulation under dc and pulse voltages

An oil-paper insulation system which will withstand DC voltage under normal conditions is a key component of converter transformers as well as high voltage direct current (HVDC) bushings. When the system changes its state, operating overvoltage appears. This kind of overvoltage will consequently affect the application of oilimmersed facilities and the safety of entire grid. Therefore, this paper studies the charge coupling behavior of double-layer oil-paper insulation under DC and pulse voltages. From the research of different pulse voltage amplitudes, pulse numbers and polarity, conclusions can be drawn that, with the increase of the pulse voltage amplitudes, DC and pulse voltages in the same polarity cause the absolute value of the initial surface potential to decrease and then rise; while in different polarities, the charge with the same polarity as the pulse voltage increases. Furthermore, for the same pulse voltage, the absolute initial value of the DC voltage applied in the same polarity is higher than that in different polarities. Considering the pulse number effect, it is obvious that the initial value increases with the increase in the pulse number, and then reaches saturation. Also, with the increase in pulse number, the decay rate decreases and thus the charge is slowly dissipated. From the tdV/dt and the decay time curves, the peak value increases with the increase in the pulse number, while the characteristic time varies by the polarity of the DC and pulse voltages.

Effect of secondary air mass flow rate on the airflow and combustion characteristics and NOx formation of the low‐volatile coal‐fired swirl burner

AbstractLaboratory experiments and industrial‐scale experiments on 300‐MW low‐volatile coal‐fired boiler were performed under deep air staging. Aerodynamic characteristics, gas temperature and concentrations, furnace temperature, and boiler efficiency were measured for various secondary air mass flow rates. Under deep air staging, a steady central recirculation zone forms near the burner nozzle. With a decreasing flow rate, the swirl intensity and maximum axial, radial, and tangential velocities decrease; between X/D = 0–0.8, the velocity decay rate decreases, and the relative reverse flow rate decreases. In the early stage, the maximum axial mixing rate decreases; the primary air concentration increases slightly. A decrease in secondary air‐box damper opening decreases the gas temperature and its increasing rate, generating a farther ignition position. In the initial stage, the O2 consumption rate and CO concentration increase, while the NOx concentration decreases. In the later stage, O2 concentration remains almost constant below 2%, and the CO concentrations exceed 15 000 ppm, which restrain NOx formation notably. Near the water‐cooled wall, flue gas temperature varies slightly, and O2 concentration exceeds 3%. Along radial direction 1.5364 ≤ R0/D0 ≤ 1.8708, the O2 concentrations are below 2%, and CO concentrations exceed 6000 ppm. A decreasing damper opening decreases furnace temperature in the primary combustion zone slightly. NOx emission decreases from 833.4 to 769.9 mg/m3 (6% O2), unburnt carbon increases from 5.18% to 6.84%, and boiler efficiency decreases from 91.53% to 90.99%. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

Luciferin-Regenerating Enzyme Mediates Firefly Luciferase Activation Through Direct Effects of D-Cysteine on Luciferase Structure and Activity.

Luciferin-regenerating enzyme (LRE) contributes to in vitro recycling of D-luciferin. In this study, reinvestigation of the luciferase-based LRE assay is reported. Here, using quick change site-directed mutagenesis seven T-LRE (Lampyris turkestanicusLRE) mutants were constructed and the most functional mutant of T-LRE (T(69)R) was selected for this research and the effects of D- and L-cysteine on T(69)R T-LRE-luciferase-coupled assay are examined. Our results demonstrate that bioluminescent signal of T(69)R T-LRE-luciferase-coupled assay increases and then reach equilibrium state in the presence of 5 mm D-cysteine. In addition, results reveal that 5 mm D- and L-cysteine in the absence of T(69)R T-LRE cause a significant increase in bioluminescence intensity of luciferase over a long time as well as decrease in decay rate. Based on activity measurements, far-UV CD analysis, ANS fluorescence and DLS (Dynamic light scattering) results, D-cysteine increases the activity of luciferase due to weak redox potential, antiaggregatory effects, induction of changes in conformational structure and kinetics properties. In conclusion, in spite of previous reports on the effect of LRE on luciferase bioluminescent intensity, the majority of increase in luciferase light output and time-course originate from the direct effects of D-cysteine on structure and activity of firefly luciferase.

Electron Spin Resonance Spectroscopy Studies on Reduction Process of Nitroxyl Radicals used in Molecular Imaging

Electron spin resonance (ESR) spectroscopy studies on the reduction process of nitroxyl radicals were carried out for 1mM concentration of 14N-labeled nitroxyl radicals in 1 mM concentration of ascorbic acid as a function of time. The half life time and decay rate were estimated for 1mM concentration of 14N labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. From the results, the increase in half life time and decrease in decay rate were calculated for TEMPONE compared with TEMPO and TEMPOL radicals, which indicates the higher stability of TEMPONE radical. The observed radical scavenging activity is also higher for TEMPONE radical. The ESR spectrum was also recorded for 1mM concentration of 14N-labeled nitroxyl radicals in pure water and the ESR parameters, line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were obtained. These results indicate that the TEMPONE radical has narrowest line width and fast tumbling motion compared with TEMPO and TEMPOL. Therefore, this study reveals that the TEMPONE radical can act as a good redox sensitive spin probe for molecular imaging.

Influence of dye-adsorption on charge carrier kinetics in TiO2 colloidal systems

Charge carrier kinetics in TiO2 powders and films was analyzed by contactless transient photoconductance (TPC) measurements in the microwave frequency regime. The difference between the behavior of powders and films was relatively small and in both cases an extended decay behavior was observed. A decrease in decay rate of the TPC signal (due to excess electrons) upon dye-sensitization after band-to-band excitation with laser pulses at 355nm was detected, which was attributed to a reduced recombination rate due to the trapping of excess holes by adsorbed dye molecules. Furthermore, it was found that adsorbed dye molecules are very efficient hole traps.

Conformational Analysis of the Electron-Transfer Kinetics across Oligoproline Peptides Using N,N-Dimethyl-1,4-benzenediamine Donors and Pyrene-1-sulfonyl Acceptors

Photoinduced intramolecular charge separation across proline-bridged donor-acceptor complexes of the type Pyr-(Pro)n-DMPD (where Pyr=pyrene-1-sulfonyl and DMPD=N,N-dimethyl-1,4-phenylenediamine) was studied. The steady-state emission spectrum for n=0, 1, 2, 3 showed an increase in emission intensity with the number of proline residues. Time-dependent emission measured by streak camera showed increasing emission signal amplitude with increasing n, along with a decrease in decay rate. In all these studies, Pyr-Pro was used as a control complex for the decay of the excited pyrene acceptor moiety without the donor DMPD. Detailed photon counting experiments carried out in DMF/water, DMF, and toluene showed single-exponential kinetics for n=0, 1 and multiexponential kinetics for n=2, 3. Rate constants observed in DMF are for n=0, k=approximately 5x10(10) s(-1); n=1, k=9.70x10(8) s(-1); n=2, k=35.9x10(8) s(-1) (70%) and 5.58x10(8) s(-1) (30%); and n=3, k=16.6x10(8) s(-1) (55%) and 3.87x10(8) s(-1) (45%). These results show that a significant percentage of the n=2 and n=3 molecules undergo faster electron transfer than for the n=1 case. Conformational analysis for Pyr-(Pro)n-DMPD molecules in water showed that whereas only one conformation is possible for n=1, eight are possible for n=2, and 32 are possible for n=3. Calculation of the free energy and electronic coupling for these conformers in water showed that only a few of these conformations have the appropriate energy and electronic coupling to be observed in the experimental time window from 20 ps to 20 ns. Assignment of the conformers undergoing electron transfer in Pyr-(Pro)n-DMPD for n=2 and 3 was based on the values for the n=1 case, for which the measured rate constant is approximately 10(9) s(-1) and the calculated electronic coupling matrix element Hda is 297 cm(-1). The similarity in ground state energy between the cis and trans conformers for n=2 and 3, their use in aqueous-organic and organic solvents, and the nature of the Pyr and DMPD acceptor and donor groups could be contributing causes for the multiexponential kinetics, which was not observed for the metal ion derivatives of proline peptides studied earlier in aqueous solution.

End Effects in Prestrained Plates Under Compression

The decay of end perturbations imposed on a rectangular plate subjected to compression is investigated in the context of plane-strain incremental finite elasticity. A separation of variables in the eigenfunction formulation is used for the perturbed field within the plate. Numerical results for the leading decay exponent are given for four rubbers: three compressible and one incompressible. It was found that the lowest decay rate is governed by a symmetric field that exhibits different patterns of dependence on the prestrain for compressible and for nearly incompressible solids. Compressible solids are characterized by low sensitivity of the decay rate to prestrain level up to moderate compression, beyond which an abrupt decrease of decay rate brings it to zero. Nearly incompressible solids, on the other hand, expose a different pattern involving interchange of modes with no decrease of decay rate to zero. Both patterns show that the decay rate obtained from linear elastic analysis can be considered as a good approximation for a prebuckled, slightly compressed plate, which is long enough in comparison to its width. Along with decaying modes, the eigenfunction expansion generates a nondecaying antisymmetric mode corresponding to buckling of the plate. Asymptotic expansion of that nondecaying mode near the stress free state predicts buckling according to the classical Euler formula. A consistent interpretation of end effects in the presence of a nondecaying mode is given.

Decay‐rate dependence of anhysteretic remanence: Fundamental origin and paleomagnetic applications

We have measured the intensity of anhysteretic remanent magnetization (ARM) as a function of alternating field (AF) decay rate. For synthetic and natural single‐domain (SD) and pseudo‐single‐domain (PSD) magnetites, ARM intensity increases as decay rate decreases. Multidomain (MD) magnetites have the opposite response, ARM increasing as the decay rate increases. These are identical to the SD/PSD and MD dependences of thermoremanent magnetization on cooling rate. For all grain sizes and domain structures, ARM intensity increases as the AF decay rate used to achieve an initial demagnetized state decreases. Decay‐rate differences in ARM intensity are a property of low‐ and medium‐coercivity grains, as shown by annealing and by stepwise AF demagnetizing samples. We interpret the SD results to mean that increased AF exposure time permits a closer approach to equilibrium magnetization. An approximate thermal activation theory based on Néel [1949] and an exact theory by Egli and Lowrie [2002] predict 6–11% increases in ARM for an order of magnitude decrease in decay rate, in reasonable accord with the observed 12% increase for 0.065 μm SD grains. For MD grains, we hypothesize that increased exposure time (slower decay) permits more efficient self‐demagnetization, reducing ARM. Low‐coercivity grains experience the largest self‐demagnetizing fields and therefore have the largest decay‐rate response. Initial‐state decay‐rate response is attributed to longer exposure times leaving domain walls more strongly pinned in deeper potential wells (the net self‐demagnetizing field is zero in the demagnetized state). Acquisition decay‐rate, annealing, and initial‐state responses of PSD grains are a blend of SD and MD responses. Because ARM is the most frequently used normalizer in relative paleointensity determination, it is important either to use a standard decay rate or else to remove the decay‐rate dependence by demagnetizing the ARM to ∼30% of its initial value (ARM0.3). A standard demagnetization level for the normalizing ARM is particularly important when comparing paleointensity records from different laboratories.

Time-resolved photoluminescence of the size-controlled ZnO nanorods

Size dependence of the time-resolved photoluminescence (TRPL) has been investigated for the ZnO nanorods fabricated by catalyst-free metalorganic chemical vapor deposition. The nanorods have a diameter of 35 nm and lengths in the range of 150 nm to 1.1 μm. The TRPL decay rate decreases monotonically as the length of the nanorods increases in the range of 150 to 600 nm. Decrease of the radiative decay rate of the exciton-polariton has been invoked to account for the results.

Size-dependent detachment-limited decay kinetics of two-dimensional TiN islands on TiN(111).

In situ high-temperature (T(a)=1050-1250 K) scanning tunneling microscopy was used to determine the coarsening and decay kinetics of two-dimensional TiN adatom and vacancy islands on atomically smooth TiN(111) terraces. We report the first observation of an abrupt decrease in decay rates, irrespective of T(a), of adatom islands with areas less than a critical value of 1600 A(2). However, no decay rate transition was observed for vacancy islands. We attribute the size-dependent island decay behavior, which is consistent with detachment-limited kinetics, to anisotropic attachment and detachment barriers.