Integral Intensity Research Articles

Temperature-dependent photoluminescence of the InAs-based and GaSb-based type-II superlattices

In this paper, we studied the optical properties of the InAs/GaSb type-II superlattice grown on InAs and GaSb substrates by temperature-dependent photoluminescence measurement from 78 K to 220 K. The PL peak wavelengths of both superlattices are gradually red-shifted and the full width at half maximum (FWHM) broadened with increasing temperature. In comparison, the FWHM of the InAs-based superlattice is narrower and less sensitive to temperature than the GaSb-based one for superlattices of similar wavelength. In addition, the integral intensity of InAs-based superlattice is almost twice that of GaSb-based one for superlattices of similar wavelength at 78 K. The thermal quenching of PL intensity of all superlattices has been analyzed by a dual-channel non-radiative recombination Arrhenius model.

Front Cover: Photoluminescence intensity ratio of Eu‐conjugated lactates—A simple optical imaging technique for biomarker analysis for critical diseases (J. Biophotonics 5/2018)

Eu3+integrated photoluminescence intensity ratio (PLIR) approach for optical detection of lactates in blood serum, plasma and confocal imaging of brain tissues has very high potential for exploitation of this technique in both in vitro monitoring and in vivo bioimaging applications for the detection of biomarkers in various diseases states. This image is diagrammatic representation of fact that the overall PLIR is higher with more lactates conjugated with Eu3+ ions.Further details can be found in the article by Tarun Kakkar et al. (e201700199). image

Microstructure anisotropy of nanocrystalline titanium produced by cryomechanical grain fragmentation

Using X-ray diffraction analysis, a systematic study was undertaken of the parameters of the deformation microstructure formed in commercially pure VT1-0 titanium as a result of cryogenic rolling at a temperature of 77 K at different degrees of compression. In order to ascertain the anisotropy of the microstructure, a comparative analysis of diffraction patterns, dimensions of crystallites (coherent scattering regions) L and microdeformation values e 2 1 / 2 in the rolling plane and in a plane perpendicular to the rolling direction was performed by comparison with the relative activity of deformation modes. As a result, anisotropy was detected in the distribution of integral intensities of diffraction peaks for mutually perpendicular planes. The established difference in the dimensions of crystallites in the rolling plane and in the plane perpendicular to the rolling direction indicates the shape anisotropy of the crystallites. The effect of morphological anisotropy of crystallites/grains is most pronounced for the nanocrystalline state. The observed complex variation in the microdeformation values e 2 1 / 2 ( e ) with compression deformation is well correlated with relative slip and twinning activity, which affect the level of local internal stresses and the possibility of their relaxation. The observed anisotropy with respect to the magnitude of microdeformations may be attributed to the presence of oriented grain boundaries associated with the shape anisotropy of crystallites/grains.Using X-ray diffraction analysis, a systematic study was undertaken of the parameters of the deformation microstructure formed in commercially pure VT1-0 titanium as a result of cryogenic rolling at a temperature of 77 K at different degrees of compression. In order to ascertain the anisotropy of the microstructure, a comparative analysis of diffraction patterns, dimensions of crystallites (coherent scattering regions) L and microdeformation values e 2 1 / 2 in the rolling plane and in a plane perpendicular to the rolling direction was performed by comparison with the relative activity of deformation modes. As a result, anisotropy was detected in the distribution of integral intensities of diffraction peaks for mutually perpendicular planes. The established difference in the dimensions of crystallites in the rolling plane and in the plane perpendicular to the rolling direction indicates the shape anisotropy of the crystallites. The effect of morphological anisotropy of crystallites/grains is mos...

Particle sizing from Fraunhofer diffraction pattern using a digital micro-mirror device and a single photodiode

In this paper, a particle sizing method using a digital micro-mirror device (DMD) and a single photodiode was proposed. Firstly, the Fraunhofer diffraction pattern was projected onto the DMD. The integral intensity of the pattern along each line array of the DMD, referred to be a projection, was captured by the photodiode line by line at the aid of a focusing lens. Secondly, the inverse Abel transform was implemented to precisely retrieve the diffraction pattern from the projections. Thirdly, the particle size distribution was reconstructed from the diffraction pattern from the integral inversion. In addition, as only one photodiode was employed, distortions caused by the non-uniformity of multiple detectors were avoided. The center of Fraunhofer diffraction pattern could be automatically located by a hierarchical searching method. Experiments were carried out to validate the proposed method on a commercial particles plate and polystyrene latex spheres. The results demonstrated that the proposed method is effective to retrieve the diffraction pattern and particle sizes.

Neurotoxicity of Cuprizone in Female and Male Rats: Electrophysiological Observations

Cuprizone induces massive demyelination in the CNS; however, the effects of cuprizone on the functions of the peripheral nervous system, as well as differential effects it may exert on males and females, have not yet been studied. Thus, we aimed to examine changes in the electromyographic characteristics of female and male Sprague-Dawley rats with cuprizone-induced demyelination. The body mass, food intake, nerve conduction velocity (NCV) along the sciatic nerve, latency, amplitude, and integral intensity (area) of the compound muscle action potential (CMAP; m. gastrocnemius) were measured weekly throughout a 4-week demyelination period, and histological sections of the brain and sciatic nerve were examined. Cuprizone led to a reduction in the NCV, CMAP amplitude and area, body mass, and food intake; simultaneously, it led to an increase in the CMAP latency. Notably, electrophysiological observations reveal that cuprizone affects both female and male rats, but males are more sensitive. This is the first study showing gender differences for the peripheral neurotoxicity of cuprizone.

Double-channel fluorimeter with pulsed excitation of advanced glycation end products in skin

A double-channel diagnostic fluorimeter operating in pulsed mode for in vivo assessment of the content of advanced glycation end products (AGEs) in skin by the autofluorescence integral intensity in the visible spectral region is developed. To excite the fluorescence we use a light-emitting diode with the peak wavelength 365 nm. A green light-emitting diode and an additional photodetection channel are intended to allow for the skin phototype of the patient. The fluorimeter analogue electronics comprises two photodetection channels based on silicon photodiodes. The accepted noise-suppressing circuitry solutions reduce the effect of sun and illumination lamp background light on the digital signal at the output of the 10-bit ADC to the one-bit level in both channels. The digital part of the fluorimeter is based on the Arduino platform. The software controls the operation modes of the fluorimeter, provides the quantitative processing of results, the diagnostic data storage and visualization. The experimental studies demonstrated the capabilities of revealing age-related changes in the skin.

Direct derivation (DD) of weight fractions of individual crystalline phases from observed intensities and chemical composition data: incorporation of the DD method into the whole-powder-pattern fitting procedure

A formula for quantitative phase analysis (QPA), called the intensity–composition (IC) formula, can be used for deriving weight fractions of individual crystalline phases in a mixture from sets of observed integrated intensities, measured in a wide 2θ range, with chemical composition data [Toraya (2016). J. Appl. Cryst. 49, 1508–1516; Toraya (2017). J. Appl. Cryst. 50, 820–829]. In this study, the IC formula has been incorporated into the whole-powder-pattern fitting (WPPF) procedure to conduct QPA. The fitting function for calculating the profile intensity at each step of the scattering angle consists of three sub-functions that represent the individual component diffraction patterns. The first sub-function calculates the diffraction pattern using a set of integrated intensities, the parameter values of which are determined by the least-squares fitting of the whole-powder pattern as is usually done by the whole-powder-pattern decomposition (WPPD) method. The second sub-function uses a set of integrated intensity parameters, which are preliminarily prepared by WPPD or may be calculated from a crystal structure model. These intensity parameters, multiplied by a scale factor, are fixed at their original values while the scale factor is adjusted in WPPF. The third sub-function uses an observed or calculated diffraction pattern multiplied by a scale factor. This diffraction pattern can be fitted directly by adjusting the scale factor. Therefore, one can fit patterns consisting of heavily broadened and degraded diffraction lines, like those of clay minerals, without being concerned with the problem of peak overlap in decomposing the diffraction pattern. The IC formula uses the total sums of the intensities under the diffraction patterns of individual phases as observed data sets; therefore, it can equally treat these intensity data sets irrespective of differences in the profile models used by the three sub-functions. The three sub-functions can arbitrarily be chosen and linearly combined, and then they can simultaneously be fitted to the observed diffraction pattern of a target mixture. The capability of the above method has been demonstrated with QPA of mixtures consisting of α-quartz, albite and kaolinite. Theories of currently used QPA techniques are reviewed from a viewpoint of the present theory and they can be interpreted as being based on the same principle, whereby the total observed intensities of individual phases are divided by the standard reference intensity per unit weight.

On the treatment of self-absorption for temperature and concentration profiles reconstruction accuracy for soot and metal-oxide nanoparticles in nanofluid fuel flame using a CCD camera

The treatment of self-absorption for temperature and concentration profiles reconstruction accuracy for soot and metal-oxide nanoparticles in a nanofluid fuel flame from the emission radiation intensities received by a charge-coupled device (CCD) camera was presented. The unattenuated radiation intensities were recovered from the values attenuated by the self-absorption of soot and metal-oxide nanoparticles through iteration calculation, and the least-square QR (LSQR) decomposition algorithm was used to deconvolute the integral unattenuated radiation intensities. The results shown that the reconstruction method considering the self-absorption can greatly improve the reconstruction accuracy of the temperature and concentration profiles, which was promising to monitor the combustion processes of nanofluid fuel flames for moderate adjusting the flame to promote the fuel combustion efficiency and decrease the pollutant emissions.

Studying the Nonlinear Optical Response from Local Polar Inhomogeneities in Strontium Barium Niobate Crystals of Different Chemical Composition

The generation of the second optical harmonic in a series of SBN-x crystals (x = 0.75, 0.61, 0.50, 0.33) is studied in the 200–900 K temperature range. It is shown that the spectral width of nonlinear response in all samples is less than 1 cm−1 and does not depend on the temperature. Its integral intensity follows the Arrhenius law. The parameters of this Arrhenius presentation are determined and compared with the corresponding parameters for a number of ferroelectrics and relaxors.

Sulphur monoxide exposes a potential molecular disk wind from the planet-hosting disk around HD 100546

Sulphur-bearing volatiles are observed to be significantly depleted in interstellar and circumstellar regions. This missing sulphur is postulated to be mostly locked up in refractory form. With ALMA we have detected sulphur monoxide (SO), a known shock tracer, in the HD 100546 protoplanetary disk. Two rotational transitions: J = 77–66 (301.286 GHz) and J = 78–67 (304.078 GHz) are detected in their respective integrated intensity maps. The stacking of these transitions results in a clear 5σ detection in the stacked line profile. The emission is compact but is spectrally resolved and the line profile has two components. One component peaks at the source velocity and the other is blue-shifted by 5 km s−1. The kinematics and spatial distribution of the SO emission are not consistent with that expected from a purely Keplerian disk. We detect additional blue-shifted emission that we attribute to a disk wind. The disk component was simulated using LIME and a physical disk structure. The disk emission is asymmetric and best fit by a wedge of emission in the north-east region of the disk coincident with a “hot-spot” observed in the CO J = 3–2 line. The favoured hypothesis is that a possible inner disk warp (seen in CO emission) directly exposes the north-east side of the disk to heating by the central star, creating locally the conditions to launch a disk wind. Chemical models of a disk wind will help to elucidate why the wind is particularly highlighted in SO emission and whether a refractory source of sulphur is needed. An alternative explanation is that the SO is tracing an accretion shock from a circumplanetary disk associated with the proposed protoplanet embedded in the disk at 50 au. We also report a non-detection of SO in the protoplanetary disk around HD 97048.

Parameter Optimization of the Radioisotope Gamma Albedo Method for Controlling Quality of Variable Composition Coals

The variant of the gamma albedo method is proposed for the radioisotope express control of coal ash content, which ensures the satisfactory accuracy under conditions of variable elemental composition of coal. It is shown that the integral intensity of the secondary (scattered and fluorescent) radiation weakened by filter of certain thickness is a univocal index of coal ash content. The analytical model for the optimization of the secondary radiation filtration parameters is developed. The utility value of the weakening filter is determined as function of ash content and composition of coal.

Influence of alkali metal cations/type of activator on the structure of alkali-activated fly ash – ATR-FTIR studies

Coal fly ash as a secondary aluminosiliceous raw material that is commonly used in the so-called geopolymerization process has been activated with different alkali hydroxides solutions: LiOH, NaOH and KOH. Changes in the aluminosilicate structure of the material during alkali-activation have been analyzed in detail on the basis of ATR/FT-IR spectra. These changes mainly affect both the integral intensity and FWHM of bands in the range of 1200–950cm−1, however dehydration and carbonation process can be also analyzed based on obtaining results.

On the fracture mechanism of a symmetric interface of glassy poly(methyl methacrylate) self-healed at a temperature well below the bulk glass transition temperature

Attenuated total reflection Fourier-transformed infrared spectroscopy (ATR-FTIR) has been used for the elucidation of the molecular mechanism of fracture of weak polymer−polymer interfaces self-healed partially at a temperature (T) well below the bulk glass transition temperature (Tgbulk). For this purpose, a symmetric interface of the carbon-chain polymer such as poly(methyl methacrylate) (PMMA) has been used. It has been found that the integral intensity and the half-width of the band ν = 1725 cm−1 for the fractured PMMA−PMMA interface self-healed at T = 64 °С, i.e. at T = Tgbulk – 45 °С, are higher as compared to those for the original PMMA surface and for the PMMA surface annealed at T = Tgbulk − 45 °С. The difference found is assigned to the chain scission of interdiffused PMMA chains resulting in the creation of new chain ends and their following oxidation.

Synthesis of Sm3+ doped SrAl2Si2O8 phosphors and improved emission intensity by Li+ doping

Sr0.95Al2Si2O8:0.05Sm3+ and Sr0.95−xAl2Si2O8:0.05Sm3+/xLi+ phosphors were synthesized by a solid-state reaction. The phase, crystal structure and luminescent properties of the synthesized phosphors were investigated. All of the synthesized phosphors have a single phase, indicating that Sm3+ and Li+ ions have doped into the SrAl2Si2O8 hosts and formed solid solutions. Under the excitation at 405 nm, Sr0.95Al2Si2O8:0.05Sm3+ and Sr0.95−xAl2Si2O8:0.05Sm3+/xLi+ phosphors show emission bands resulting from the 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions of Sm3+. The codoped Li+ ions could enhance the emission intensity of Sm3+. Sr0.9Al2Si2O8:0.05Sm3+/0.05Li+ phosphor has a good thermal stability. The integral intensity at 225 °C is about 65% of the initial intensity at 25 °C.

Linear and Nonlinear Thermal Lens Signal of the (Δν = 6) C-H Vibrational Overtone of Naphthalene in Liquid Solutions of n-Hexane.

The thermal lens technique is applied to vibrational overtone spectroscopy of solutions of naphthalene (C10H8) in liquid hexane. The C-H fifth vibrational (Δν = 6) overtone spectrum of C10H8 is detected at room temperature for mole fractions from 0.08 to 19 × 10-6 using n-C6H14 as solvent. By detecting the absorption band in a 19 ppm (parts per million) solution, the peak absorption of the signal is approximately (2.2 ± 0.3) × 10-7 cm-1. A plot of normalized integrated intensity as a function of the mole fraction of naphthalene in solution reveals a dependence of the magnitude of the signal with the probe laser wavelength. If the wavelength of the probe laser is 568 nm, the thermal lens signal (TLS) is linear as a function of the mole fraction of the solution. When the wavelength of the probe laser is 488 nm, the TLS is nonlinear as a function of the concentration. Three different models of nonlinear absorption are discussed. A two-color absorption model that includes the simultaneous absorption of the pump and probe lasers could explain the enhanced magnitude and the nonlinear behavior of the TLS for solutions of mole fraction < 0.1%.

Simultaneous luminescence and magnetic control of NaLuF4: Yb3+/Er3+ by introducing NaMnF3 and the application for detecting basic fuchsin

In this work, we reported NaLuF4:Yb3+/Er3+ optical-magnetic bifunctional material by a facile hydrothermal method. The modulation of luminescent and magnetic properties by introducing the secondary phase NaMnF3 was investigated in detail. It was found that the multi-color emissions of the proposed material can be easily controlled due to the energy level match between the Mn and the lanthanide ions. In addition, these microcrystals presented paramagnetic and ferromagnetic property, and the relative intensity showed an opposite variation to the content of NaMnF3 phase. Finally, we briefly discussed the dye detection based on this bifunctional material as fluorescent probe, and the integral intensity ratio of red to green emission was found being sensitive to the concentration of the basic fuchsin (BF), and a detection limit of 0.0015 μg/ml was achieved. These findings can be helpful to understand NaMnF3 induced optical-magnetic property modulation and provide some applications in the biosensing and bioimaging area.

Solid-State 13C CP/MAS NMR for Alkyl-O-Aryl Bond Determination in Lignin Preparations

Several lignin preparations (Freudenberg lignin, Björkman lignin, and Pepper lignin), technical lignins (soda, soda-AQ, Kraft, Kraft-AQ, and hydrolysis), dimeric lignin model compounds, and different polysaccharides (galactoglucomannan, arabinogalactan, xylan, and arabinan) were analyzed by means of solid-state 13C CP/MAS NMR. Signals assignment in solid-state NMR lignin spectra was performed on the basis of the conducted studies and earlier published data. It was established that there exists strong linear correlation (r = 0.985) between Alkyl-O-Aryl inter-unit bond content in lignin and integral signals intensity in NMR spectra in the range of chemical shifts of 96–68 ppm. The integral signals intensity was measured in correlation with the reference integral signals in the range of chemical shifts of 162–102 ppm, typical for aromatic carbon atoms. To eliminate the effect, caused by carbohydrates contained in lignin, the correction factor of 0.67% of the area of integration per 1% of carbohydrates was determined. It was shown that the solid-state 13C CP/MAS NMR method allowed to determine Alkyl-O-Aryl bond content in both soluble and insoluble lignin preparations, and also to determine methoxyl groups content in soluble preparations.

An automated epifluorescence microscopy imaging assay for the identification of phospho-AKT level modulators in breast cancer cells

AKT is an enzyme of the PI3K/pAKT pathway, regulating proliferation and cell survival. High basal levels of active, phosphorylated AKT (pAKT) are associated with tumor progression and therapeutic resistance in some breast cancer subtypes, including HER2 positive breast cancers. Various stimuli can increase pAKT levels and elevated basal pAKT levels are a feature of PTEN-deficient breast cancer cell lines. The aim of this study was to develop an assay able to identify modulators of pAKT levels using an automated epifluorescence microscope and high content analysis. To develop this assay, we used HCC-1569, a PTEN-deficient, HER2-overexpressing breast cancer cell line with elevated basal pAKT levels. HCC-1569 cells were treated with a selective pharmacological inhibitor of AKT (MK-2206) to reduce basal pAKT levels or EGF to increase pAKT levels. Immunofluorescence images were acquired using an automated epifluorescence microscope and integrated intensity of cytoplasmic pAKT staining was calculated using high content analysis software. Mean and median integrated cytoplasmic intensity were normalized using fold change and standard score to assess assay quality and to identify most robust data analysis. The highest z′ factor was achieved for median data normalization using the standard score method (z′ = 0.45). Using our developed assay we identified the calcium homeostasis regulating proteins TPRV6, STIM1 and TRPC1 as modulators of pAKT levels in HCC-1569 cells. Calcium signaling controls a diverse array of cellular processes and some calcium homeostasis regulating proteins are involved in modulating pAKT levels in cancer cells. Thus, these identified hits present promising targets for further assessment.

Raman and EPR spectroscopic studies of chromium-doped diamond-like carbon films

The diamond-like carbon (Cr-free DLC) and chromium-doped DLC (Cr doped-DLC) films prepared by a hybrid technology using a combination of pulsed laser deposition and magnetron sputtering were studied by Raman and electron paramagnetic resonance (EPR) spectroscopy. Raman spectra are dominated by the well-known carbon (D/G) band. The intensity ratio of the D/G bands was found to increase with the increase of the Cr content. Careful elimination of the substrate-related (SiO2) peaks enabled us to identify new weak features attributable to the presence of the CCr bonds. Two EPR signals were observed in Cr-free and Cr-doped DLC films. The EPR signal at g = 2.0025(3) was attributed to the sp2 coordinated carbon-related defect (CRD) and the second EPR signal at g = 2.0064 was assigned to the Pb0 interface defect which may appear due to the formation of the oxidized Si on the interface of the DLC film and SiO2 substrate. The observed temperature behavior of the CRD EPR signal g-factor in Cr free DLC films was described by the model of exchange coupled two spin systems (localized defects and conduction electrons) in the bottleneck regime. From the temperature dependence of the linewidth and integral intensity of the CRD EPR signal it was concluded that ferromagnetic ordering occurs in the spin system with exchange constant of J = 0.069 meV. The spin density of the CRD was found to be significantly decreased in Cr-doped DLC films, possibly due to the formation of the CCr bonds. The observed change of the CRD lineshape from Lorentzian in Cr free DLC films to Gaussian in Cr-doped DLC films indicates that there is a superhyperfine coupling between unpaired spins of the CRD and surrounding Cr nuclei.

Investigations Of A Helium Plasma Jet In Interaction With Biological Liquids

For the plasma medicine community it is of high interest to understand the physicochemical mechanisms concerning the effects of plasmas on living cells and cancerous cells, in particular. A first step is to study the effects produced upon biological liquids, as they represent the exchange environment for most biological process. After plasma exposure of liquids, minor changes of the basic parameters such as pH, ionic strength or chemical composition can lead to a major biological impact. Thus, this indirect effect of plasma treatment on cells behaviour must also be addressed during plasma cancer studies, together with direct exposure. In this context, the present experiments are focused on the plasma production and transfer of oxygen and nitrogen reactive species to a liquid target, e.g. ultra pure water or phosphate-buffered saline. The plasma source consists of a helium plasma jet in a barrier discharge configuration, operated at atmospheric pressure which interacts with solutions up to 40 minutes. Electrical and optical monitoring of the plasma jet was performed over the entire exposure duration, using high speed techniques, in order to assess the plasma jet warm-up period and settling time [1], with and without liquid target. Molecular beam mass spectrometry of the jet confirmed the presence in the various negative and positive ions based on oxygen and nitrogen species [2]. Download : Download high-res image (303KB) Download : Download full-size image Fig. 1. Influence of elapsed time on peak values of the current (Imax), time (tImax) and O (777 nm) line integral intensity. The ultraviolet absorption spectra of liquids, in the 200 - 400 nm wavelength range, were acquired immediately after exposure and they were repeated up to 14 days, in order to monitor the liquid chemistry evolution. Using spectral deconvolution, we monitored the variation of absorption bands corresponding to the following species: O2, NO2-, NO3 - , H2O2 and O3. We observed an increase of the O2 and NO2 - bands, while the absorption bands related to all other species remain unchanged.