Inspection of Radiation Shielding Proficiency and Effect of Gamma-Ray on ESR and Thermal Characteristics of Copper Oxide Modified Borate Bioglasses

Samples of copper-modified bioactive borate glasses were synthesized and their radiation shielding properties including gamma-ray and neutron radiation shielding were investigated. Further, the glasses’ mass attenuation coefficients were measured with a NaI(Tl) detector while their gamma-ray shielding parameters were estimated using Phy-X/PSD program. Free-radical densities were measured via electron spin resonance to estimate the absorbed doses during accidental irradiation. The extensive reduction of the dose detection threshold (2 Gy) required the estimation of the signal of the non-irradiated sample. In addition, the effects of applied microwave power and absorbed dose on synthesized samples were studied. Finally, the thermal annealing of the emerging peaks, which were due to the irradiation signal-to-noise ratio and energy dependence, was studied to estimate the stabilities of such peaks. This modified material is recommended to detect and monitor the gamma-radiation dose because of its good dosimetric properties. Finally, regarding the presence of the two borate groups, triangular and the tetrahedrally coordinated, in their definite and typical wavenumbers, the FTIR spectra displayed simplified vibrations that were close to those of many bioglasses. This paper provides complementary results for the author's previous research examining this glass for low photon dose measurements using luminescence characteristics.

     

More electromagnetic energy converged by the assembly of magnetic resonator and antennas

The interaction of magnetic resonators connected by nano-antennas is studied for the first time. Compared to a simple magnetic resonator, the absorptance can be obviously much enhanced and more electromagnetic energy can be converged by the assembled magnetic resonator and nano-antennas (nano-strip). The nano-strip plays the role of both nano-antenna and phase tuner for propagating surface plasmon polaritons (SPPs). The interaction of localized surface plasmon resonance and propagating SPPs can remarkably be tuned by simply changing the width of nano-strips. When lattice coherence happens at the magnetic resonance, maximum enhancements of local field are achieved. This approach paves a new way for the design of a metamaterial based on magnetic resonators.     

Cavitation Clusters in Lipid Systems: The Generation of a Bifurcated Streamer and the Dual Collapse of a Bubble Cluster

Several studies have reported the use of high-intensity ultrasound (HIU) to induce the crystallization of lipids. The effect that HIU has on lipid crystallization is usually attributed to the generation of cavities but acoustic cavitation has never been fully explored in lipids. The dynamics of a particular cavitation cluster next to a piston like emitter (PLE) in an oil was investigated in this study. The lipid systems, which are important in food processing, are studied with high-speed camera imaging, laser scattering, and acoustic pressure measurements. A sequence of stable clusters was noted. In addition, a bifurcated streamer was detected, which exists within a sequence of clusters. This is shown to originate from two clusters on the PLE tip oscillating with a 180° phase shift in time with respect to one another. Finally, the collapse phase of the cluster is shown to involve a rapid (~10 μs) two-stage process. These results show that the dynamics of cluster formation and collapse is driven by HIU power levels and might have implications in lipid sonocrystallization.     

Second-order statistical regression and conditioning of replicate transient kinetic data

A new method has been developed to estimate physico-chemical parameters from transient kinetic data: second-order statistical regression (SOSR). It allows to account for heteroskedasticity and nonwhiteness of the noise in the time series measured. SOSR makes use of replicates to estimate the second-order statistics, i.e. the autocovariance pattern of the noise. A sample principal noise component analysis of the experimental time series allows nonlinear least-squares (NLSQ) regression of the latter. The method has been validated by regression of artificially generated experimental data and the results have been compared with those obtained with direct NLSQ regression. The SOSR has also been applied to the irreversible adsorption of oxygen on a reduced vanadia/silica catalyst and the interaction of propane with a copper/ceria catalyst, as studied with a temporal analysis of products (TAP) setup. In general, compared with those obtained with direct NLSQ regression, the parameter estimates and their confidence intervals are more accurate.     

Study of diamond films grown at low temperatures and pressures by ECR-assisted CVD

We have studied a set of diamond films grown at low temperatures and pressures by electron cyclotron resonance (ECR)-assisted chemical vapor deposition (CVD). These films were grown on Si (100) substrates at temperatures ranging between 550 and 710 °C and pressures ranging between 1 and 2 Torr. Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were employed to investigate the crystalline quality, diamond yield, and stresses developed in these films. Our Raman lineshape analysis indicates that most of the diamond films exhibit a net compressive stress. An estimate of the net stresses developed in these films was made by adding the thermal interfacial stress component to the calculated stress developed at the grain boundaries from the X-ray analysis. It was found that the residual stress is compressive in nature, but less compressive than that calculated from the Raman shift. The net stress exhibits a strong correlation with the relative amount of non-sp³ phase, thus implying that the non-sp³ phase is causing the measured excess compressive stress. However, the crystalline quality of the diamond phase improves as the overall non-sp³ component increases, thus indicating a process analogous to phase segregation within the films. These results indicate that the source of the excess compressive stress is non-sp³-bonded carbon accumulated at the grain boundaries.     

Application of the bio-inspired Krill Herd optimization technique to phase equilibrium calculations

The Krill Herd optimization technique, which is based on the simulated herding behaviour of the krill crustacean, is applied to calculations involving phase equilibrium and phase stability, as the application of this emerging technique is extremely limited in the literature. In this work, the Krill Herd algorithm (KH)¹ and the modified Lévy-flight Krill Herd algorithm (LKH)² has been applied to phase stability (PS)³ and phase equilibrium calculations in non-reactive (PE)⁴ and reactive (rPE)⁵ systems, where global minimization of the total Gibbs energy is necessary. Several phase stability and phase equilibrium systems were considered for the analysis of the performance of the technique that includes both vapour and liquid phase conditions.The Krill Herd algorithm was found to reliably determine the desired global optima in PS, PE and rPE problems with generally higher success rates and lower computing time requirements than previously applied metaheuristic techniques such as those involving swarm intelligence and genetic and evolutionary algorithms.     

Analysis of a high power ferrite differential phase shift circulator operating above ferrimagnetic resonance

Magnetic losses limit the power handling/frequency performance of all ferrite phase shift and control components. At high power levels nonlinear loss is prevalent but this can be avoided using a technique called ‘mode segregation’. It is noted that this is achieved by biasing the ferrite above ferrimagnetic resonance. A combined magnetostatic/microwave finite element scheme is used to model this mode of operation in a differential phase shift structure used in air traffic control surveillance radars. Starting from the nonlinear material magnetisation curve, the magnetic state of the ferrite is evaluated as a prerequisite to calculating the full microwave solution. Above resonance operation avoids nonlinear loss but this study indicates that the differential phase shift is reduced and larger magnetic bias fields are required. Calculations agree well with the experimental data.     

Multi step energy transfer between three Si_LTL and SiGe_LTL zeolite-loaded dyes

We report a novel potential light-harvesting antenna material constructed with three dyes loaded on two types of zeolite LTL (SiGe_LTL and Si_LTL). Fluorescence resonance energy transfer (FRET) occurs from acridine hydrochloride (Ac) to Thionine acetate (Th) via Acriflavine hydrochloride (AF), which acts as an antenna to receive and transfer energy from Ac to Th. We compared multistep FRET systems based on dye-loaded SiGe_LTL paired with an Si_LTL-based system. Our results show that in both cases, FRET efficiency increases with Th loading and decreases with increasing AF loading. Moreover, the zeolite LTL microenvironment causes a red shift in the fluorescence spectra of the three SiGe_LTL-loaded-dyes compared to those of the Si_LTL-based dyes.     

A Genetic Algorithm Based Approach to Coalescence Parameters: Estimation in Liquid‐Liquid Extraction Columns

The population balance model is a useful tool for the design and prediction of a range of processes that involve dispersed phases and particulates. The inverse problem method for the droplet population balance model is applied to estimate coalescences parameters for two‐phase liquid‐liquid systems. This is undertaken for two systems, namely toluene/water and n‐butyl acetate/water in a rotating disc contactor (RDC), using a droplet population balance model. In the literature, the estimation procedure applied to this problem is often based on the deterministic optimization approach. These methods generate instabilities near a local minimum, inevitably requiring information about the derivatives at each iteration. To overcome these limitations, a method providing an estimate for the coalescences parameters is proposed. It is based on a simple and adapted structure of the genetic algorithm, for this particular problem. The agreement between the experimental observations and the simulations is encouraging and, in particular, the models used have proven to be suitable for the prediction of hold‐up and Sauter diameter profiles for these systems. Finally, these results demonstrate that the optimization procedure proposed is very convenient for estimating the coalescences parameters for extraction column systems.     

Image-Based Method to Quantify Decellularization of Tissue Sections

Tissue decellularization is typically assessed through absorbance-based DNA quantification after tissue digestion. This method has several disadvantages, namely its destructive nature and inadequacy in experimental situations where tissue is scarce. Here, we present an image processing algorithm for quantitative analysis of DNA content in (de)cellularized tissues as a faster, simpler and more comprehensive alternative. Our method uses local entropy measurements of a phase contrast image to create a mask, which is then applied to corresponding nuclei labelled (UV) images to extract average fluorescence intensities as an estimate of DNA content. The method can be used on native or decellularized tissue to quantify DNA content, thus allowing quantitative assessment of decellularization procedures. We confirm that our new method yields results in line with those obtained using the standard DNA quantification method and that it is successful for both lung and heart tissues. We are also able to accurately obtain a timeline of decreasing DNA content with increased incubation time with a decellularizing agent. Finally, the identified masks can also be applied to additional fluorescence images of immunostained proteins such as collagen or elastin, thus allowing further image-based tissue characterization.     

Phase transition of LCP fluids confined in nanochannels through MD simulation

Manipulation of molecular orientation alignment in MCTLCPs (main-chain thermotropic liquid crystalline polymers) by pure shear at nano scale has been investigated for the first time using molecular dynamics (MD) simulation. Results indicate that high planar shear induces long-range uniform orientation ordering (liquid crystalline phase) of initially randomly orientated molecules of MCTLCP fluid confined in a nanochannel, which is confirmed by analyzing the orientation order parameter and the snapshots of MCTLCP liquid in a nanochannel under different shear rates. Insights into the origin of the phase transition phenomena are given at molecular level through investigating the thermodynamic density distribution of MCTLCP molecules in the nanochannel, suggesting that the energy shift due to a radical jump of system density affects both the magnitude and the orientation of the molecular ordering. Simulation results also show that there is a critical shear rate for transforming isotropic phase into liquid crystalline phase. The critical shear rate is dependent on the temperature of the MCTLCP system. Findings in this paper may present useful information for processing TLCP molecules at nano scale and the understanding of nanoflow.     

The direct influence of the support on the electronic structure of the active sites in supported metal catalysts: evidence from Pt–H anti-bonding shape resonance and Pt–CO FTIR data

The catalytic activity and spectroscopic properties of supported noble metal catalysts are strongly influenced by support properties such as the presence of protons, type of charge compensating cations, Si/Al ratio and/or presence of extra-framework Al. The metal–support interaction is relatively independent of the metal (Pd or Pt) or the type of support (microporous zeolites such as LTL and Y or macroporous supports such as SiO₂). As the alkalinity of the support increases (i.e., with increasing electronic charge on the support oxygen ions), the TOF of the metal particles for neopentane hydrogenolysis decreases. At the same time, there is a systematic shift from linear to bridge bonded CO as indicated by the IR spectra. This is a strong indication of a change in the electronic structure of the catalytically active Pt surface atoms. Analysis of the Pt–H anti-bonding shape resonance present in the Pt X-ray absorption spectra of the L₃ edge indicates that the difference in energy between the Pt–H anti-bonding orbital and the Fermi level decreases as the alkalinity of the support increases. The results from the IR and Pt–H shape resonance data directly show that the support influences the position in energy of the metal valence orbitals. The ionisation potential of the catalytically active Pt surface atoms decreases with increasing support alkalinity, i.e., with increasing electron charge on the support oxygen ions. This shift leads to a weakening of the Pt–H bond.     

Estimation of nonlinear oscillations by an energy method

The mean output and amplitude of the limit cycle in an oscillating nonlinear system with a small parameter can be estimated in a simple manner through an integral energy method. The results agree with the tedious Poincaré-Lindstedt and Krylov-Bogoliubov methods and can be applied easily to high order systems for which the latter techniques are not practical. Conditions under which process oscillations lead to a favorable shift in the mean output are obtained early in the analysis and independently of the estimate of the limit cycle amplitude.     

AC Electrokinetic Fast Mixing in Non-Parallel Microchannels

A novel ultra-fast micromixer of a quasi T-channel with electrically conductive sidewalls is presented here and some new phenomena in its mixing process are observed and reported. The mixing is about 10²–10³ times faster than that by purely molecular diffusion, and about 10² times faster than that in existing micromixers, which are based on the electrokinetic instability (EKI). Both parallel and non-parallel channel are investigated and compared by evaluating their mixing. Mixing behaviors in the microchannels are studied in terms of scalar concentration distributions. It is found that with a small angle (about 5° in this case) between the two electrodes sidewalls, mixing can be enhanced rapidly at even low AC voltage. The influence of the applied AC voltage phase shift between the two electrodes on the mixing process is also explored. The result reveals that the mixing is the strongest under a 180° signal phase shift. Fast mixing is also achieved under high AC frequency in this micromixer. Fluorescent micro particles are used to visualize the flow pattern for better understanding of the mixing enhancement mechanism. The design of this micromixer could provide new opportunity for applications where fast mixing is demanded.     

Phase separation in polymer blend thin films studied by differential AC chip calorimetry

AC chip calorimetry is used to study the phase separation behavior of 100 nm thin poly(vinyl methyl ether)/poly(styrene) (PVME/PS) blend films. Using the on-chip heaters, very short (10 ms-10 s) temperature jumps into the temperature window of phase separation are applied, simulating laser heating induced patterning. These temperature pulses produce a measurable shift in the glass transition temperature, evidencing phase separation. The effect of pulse length and height on phase separation can be studied. The thus phase separated PVME/PS thin films remix rapidly, in contrast with measurements in bulk. AC chip calorimetry seems to be a more sensitive technique than atomic force microscopy to detect the early stages of phase separation in polymer blend thin films.     

Li_2S－B_2O_3－LiBr体系硫氧化物玻璃锂离子导体

用液氮淬冷法制得了Ｌｉ＿２Ｓ－Ｂ＿２Ｏ＿３－ＬｉＢｒ体系硫氧化物玻璃。研究了网络修饰剂Ｌｉ＿２Ｓ和掺杂剂ＬｉＢｒ对玻璃转化温度和电导率以及网络基团结构的影响。结果表明：在Ｌｉ＿２Ｓ－Ｂ＿２Ｏ＿３玻璃中，随着Ｌｉ＿２Ｓ含量增加，玻璃转化温度和活化能增加，并在Ｌｉ＿２Ｓ的摩尔含量约为３０％时达到最大值；ＬｉＢｒ的加入使玻璃转化温度降低，但提高了玻璃电导率。根据１１＿ＢＮＭＲ测定计算了四配位硼基团的分数值，ＸＰＳ测定了桥硫和非桥硫的存在。讨论了结构变化对玻璃性能的影响。     

Instantaneous measurement of the internal temperature in lithium-ion rechargeable cells

We demonstrate, in three different rechargeable lithium-ion cells, the existence of an intrinsic relationship between a cell's internal temperature and a readily measurable electrical parameter, namely the phase shift between an applied sinusoidal current and the resulting voltage. The temperature range examined spanned from −20 to 66 °C. The optimum single frequency for the phase measurement is in the 40–100 Hz range, allowing for a measurement time of much less than a second; the phase shift in this range depends predominantly on temperature, and is almost completely independent of the state-of-charge. Literature reports suggest that the observed dependence of the phase shift on temperature arises from the ionic conduction of the so-called solid-electrolyte-interphase layer between the graphite anode and the electrolyte. A meter measuring the phase shift across this interphase is analogous to a thermometer reporting the temperature, thereby providing feedback for rapid corrections of any operating conditions that might lead to the catastrophic destruction of the cell. This level of monitoring and control is distinctly different from the present safety-enabling mechanisms: typically positive thermal coefficient ceramics/plastics, or “shutdown” separators based on polyethylene that act to often permanently shut down current flow through the cell.     

Phase stability,fuel properties,and diesel engine performance of palm-oil-based microemulsion biofuels

Microemulsification and blending are two viscosity-modifying techniques of vegetable oils for direct use with diesel engine. In this study, alcohol blends are mixtures of ethanol, diesel, and palm-oil biodiesel while microemulsion biofuels are thermodynamically stable, clear, and single-phase mixtures of diesel, palm oil, and ethanol stabilized by surfactants and cosurfactants. Although there are many studies on biofuels lately, there is limited research on using biodiesel as a surfactant in microemulsion formulations and applied on engine performance at different engine loads. Therefore, the objectives are to investigate phase stability and fuel properties of formulated biofuels (various blends and microemulsions), to determine the engine performance at different engine loads (no load, and from 0.5 to 2.0 kW), and to estimate laboratory-scale cost of the selected biofuels compared to diesel and biodiesel. The results showed that phase stability and fuel properties of selected microemulsion biofuels are comparable to diesel and biodiesel. These microemulsion biofuels can be applied to the diesel engine at different loads while diesel-ethanol blends and palm-oil-biodiesel-ethanol blends cannot be. It was found that the energy efficiencies of the system using microemulsion biofuels were slightly lower than the average energy efficiency of diesel engine. From this study, it can be summarized that microemulsion biofuels can be formulated using palm-oil biodiesel (palm-oil methyl ester) as a bio-based surfactant and they can be considered as environmentally-friendly alternatives to diesel and biodiesel. However, cost considerations showed that the raw materials should be locally available to reduce additional costs of microemulsion biofuels.     

2,5-双〔4-(N,N-二苯基)氨基苯基〕吡啶的合成及光谱性质

三芳胺是传统的空穴传输材料,该文将其引入磷光配体2-苯基吡啶中,得到一种具有双重性质的磷光配体2,5-双〔4-(N,N-二苯基)氨基苯基〕吡啶,并通过元素分析,核磁共振氢谱对其结构进行了确认。通过比较其与另外两种磷光配体在二氯甲烷中的紫外吸收光谱和光致发光光谱表明,由于二苯胺这样一个强供电子性基团的引入,增强了π电子的离域范围,降低了这种磷光配体的HOMO轨道和LUMO轨道之间的能壑,使其最大吸收峰波长红移99 nm,最大发射峰波长红移48 nm,且吸收和发射的强度增加,Stokes位移为72 nm。     

Time-of-flight studies on catalytic model reactions

Time-of-flight spectroscopy (TOF) and REMPI-TOF (resonance enhanced multi-photon ionization-TOF) were applied to measure the angular and translational energy distribution, as well as the internal state resolved energy distribution of desorption and reaction products on some model systems. Desorption of hydrogen and deuterium from clean and modified Pd(111) surfaces was studied, where the palladium sample was part of a permeation source. Water formation by reaction of oxygen with hydrogen on palladium was investigated by using different types of hydrogen supply: molecular H₂ exposure and atomic H exposure from the gas phase, as well as H exposure by permeating hydrogen. Vanadium oxide nanostructures on Pd(111) were prepared and the influence on D₂ desorption and D₂O production was investigated with the permeation technique. Additionally, deuterium desorption from sulfur and oxygen covered V(111) and V(100) surfaces was studied by TOF and REMPI-TOF spectroscopy. From the TOF spectra information concerning the reaction and desorption dynamics (activation barriers) could be gained.