Variability in molecular composition and optical absorption of atmospheric brown carbon aerosols in two contrasting urban areas of China

Atmospheric brown carbon (BrC) aerosols were investigated at two urban sites in southern (Hefei) and northern (Shijiazhuang) China during summer and winter of 2019-2020 to explore regional variability in their compositional and optical properties. Organic matter in ambient PM2.5 samples were characterized at molecular level using ultrahigh performance liquid chromatography coupled with a diode array detector and an Orbitrap mass spectrometer. Although the molecular composition of organic aerosols varied substantially over different ambient environments, they were mainly composed by CHO and CHON species in positive ionization mode while CHO and CHOS species in negative mode. The mass absorption coefficients of BrC aerosols at wavelength range 250-450 nm were relatively higher for winter samples in both cities and for Shijiazhuang samples in both seasons, partly attributed to the higher concentration levels of anthropogenic air pollutants in these environments. The absorption Ångström exponents further revealed that BrC aerosols in winter seasons and in Shijiazhuang had a greater capacity of absorption at shorter wavelengths. A total of 26 BrC species with strong absorption were unambiguously identified from different environments, which mainly consisted of CHO, CHON, and CHN species and had higher degrees of unsaturation and lower degrees of oxidation. The presence and abundance of these BrC species varied dynamically across the seasons and cities, with a greater number of species presented in the winter of Shijiazhuang. The BrC species together contributed 12-26 % in the total absorbance of light-absorbing organic components at 250-450 nm. This study highlights the regional differences in BrC properties influenced by the sources and atmospheric processes, which should be taken into account to assess their climate impacts.

Characterization of nitrated aromatic compounds in fine particles from Nanjing, China: Optical properties, source allocation, and secondary processes

Recently, nitrated aromatic compounds (NACs) have received much attention due to their role as key chromophores of brown carbon (BrC) and their impact on human health and the climate. In this study, a method for detection of 12 NACs in the atmosphere was developed and applied to the detection of 191 atmospheric samples in the northern suburbs of Nanjing in 2017. The average concentration of total NACs in Nanjing was 26.48 ng m^-3, which was lower than that in North China. The total NACs also showed obvious seasonal variation, with the highest concentration in winter (51.99 ng m^-3) and the lowest concentration in summer (11.26 ng m^-3). Moreover, the contribution of subcomponents of NACs also changed with the seasons. Nitrophenols (NPs) and nitrocatechols (NCs) were most abundant in winter, while nitrosalicylic acids (NSAs) were more abundant in summer, accounting for 30%, 27%, and 85%, respectively. The reason for this result may be due to the different sources of dominance of NACs in different seasons. The light absorption of NACs to water-soluble BrC was mainly concentrated in the 300-400 nm range, and its contribution reached the maximum at 310 nm. NPs and NCs had the highest contribution to BrC among all NACs in winter, with a range of 25-54% and 3-59%, respectively. The Positive Matrix Factorization (PMF) was used to analyze the main sources of NACs in different seasons. Secondary generation was the largest source in summer, accounting for 43.5%, and biomass combustion contributed the most in autumn, accounting for 36.7%. NACs are affected by temperature, especially in summer, and the subcomponents vary in temperature dependence. The secondary generation process of NACs is affected by NO₂ and O₃, especially when NO₂ is greater than 40 μg m^-3 and O₃ is less than 220 μg m^-3.

Investigation of silk as a phantom material for ultrasound and photoacoustic imaging

Comprehensive characterization of biomedical imaging systems require phantoms that are easy to fabricate and can mimic human tissue. Additionally, with the arrival of engineered tissues, it is key to develop phantoms that can mimic bioengineered samples. In ultrasound and photoacoustic imaging, water-soluble phantom materials such as gelatin undergo rapid degradation while polymer-based materials such as polyvinyl alcohol are not conducive for generating bioengineered tissues that can incorporate cells. Here we propose silk protein-based hydrogels as an ultrasound and photoacoustic phantom material that has potential to provide a 3D environment for long-term sustainable cell growth. Common acoustic, optical, and biomechanical properties such as ultrasound attenuation, reduced scattering coefficient, and Young's modulus were measured. The results indicate that silk acoustically mimics many tissue types while exhibiting similar reduced optical scattering in the wavelength range of 400-1200 nm. Furthermore, silk-based materials can be stored long-term with no change in acoustic and optical properties, and hence can be utilized to assess the performance of ultrasound and photoacoustic systems.

Optical Absorption Investigations for efficient Crystal Violet Dye removal from wastewater via Carbon nanotubes: Montmorillonite based Nanocomposite

The current study reports a facile method to fabricate functionalized multi-walled carbon nanotubes and montmorillonite clay mineral-based nano-composite matrix and its detailed characterization using spectroscopic and morphological techniques. The nanocomposites have been studied for their potential applications in the treatment of contaminated water using batch adsorption studies. The investigations conducted using optical absorption spectroscopic measurements for the adsorption process indicate that the nanocomposite matrix can effectively remove almost 98% of the dye from aqueous solution. The nanocomposites have showed fast and strong adsorption behaviour for the dye with the maximum adsorption capacity (q_m ) of ~ 467.3 mg g^-1 in 25 min. The experimental data at equilibrium were also correlated with the theoretical adsorption isotherm and kinetic models. The results demonstrate that the experimental data fits well to the Freundlich adsorption isotherm model and conforms to second order kinetics. Furthermore, the nanocomposite exhibits good recyclability without any marked decrease in the adsorption performance even after five adsorption cycles of usage which indicates its potential application as reusable adsorbent for the efficient removal of hazardous dyes from contaminated water.

Syndiotactic hexamer peptide nanodots

Spatial confinement of excitons in the nano-crystalline region of semiconducting nanostructures differ significantly from the optoelectronic properties exhibited by the bulk material. We report spike-like absorption observed in the UV spectrum of a phenylalanine hexamer peptide [(Ff)₃-OH] nano-assembly, which may be attributed to the spatial confinement of electrons to the dimension of quantum dots. Interdependency of the UV and PLE spectrum of the peptide confirms the existence of quantum confinement in (Ff)₃-OH nano-assemblies.

Influence of multi valent states of vanadium ions in ZnO doped novel calcium fluoro phosphate bio glasses

ZnO-CaF₂-P₂O₅ glasses doped with different concentrations of V₂O₅ (ranging from 0 to 1.0 mol %) were prepared. The prepared bio glasses are soaked in SBF for duration of 2, 3, 7 and 10 days in separate plastic containers and then kept in incubator maintained at body temperature 36.5 °C. The influence of valence states of vanadium ions (V⁴⁺/V⁵⁺) with respect to the structural aspects by means of FTIR and Raman Spectra, elastic properties by means of relevant parameters, the thermal stability by means of DTA studies and other spectroscopic properties by using OA and ESR studies are studied. The raise in wavenumber and comparative areas of the two absorption bands corresponding to electronic transitions 2B_2g → E_2g, 2B_2g → 2B_1g respectively in optical absorption spectra of these CZPV glasses clearly indicate that vanadium ions have octahedral co-ordination with tetragonal compression due to modifier action of V₂O₅in the glass network. The optical absorption and ESR studies have revealed that vanadium ions exist in V⁴⁺ states. The characteristic temperatures of these prepared glasses obtained from DTA curves explain modifications taking place in the structure of glass network. The structural changes are explained with the aid of FTIR and Raman studies. The bio active nature of the titled glasses is evident from dissociation and pH studies by SEM &EDS of these glasses before and after immersion into SBF.

2D XBiSe3(X = Ga, In, Tl) monolayers with high carrier mobility and enhanced visible-light absorption

The geometrical configurations of the XBiSe₃ (X = Ga, In, Tl) monolayers are identified by employing the first-principles density functional theory calculations, and the stabilities are confirmed by phonon dispersion, formation energy, and ab initio molecular dynamics simulation, respectively. The bandgap and band edges, the density of states, the optical absorption, mobility, and effect of strain engineering are evaluated to understand the photoelectronic properties of the monolayers. The results show that the XBiSe₃ monolayers have the indirect bandgaps of 1.14-1.69 (1.20-1.84) eV by HSE06(GW), leading to the enhanced optical absorption from the visible to near-ultraviolet region. The large mobility of the electron and hole are also observed, which is helpful for the separation and transfer of the photogenerated carrier pair. The band edges and bandgaps, as well as the optical absorptions, can effectively be tuned by strain engineering. It should be noted that the band edges of the InBiSe₃ monolayer could satisfy the condition of redox potential for the hydrogen evolution reaction under the compressive strain heavier than -3%, implicating this monolayer can also be used for photocatalytic water splitting to produce hydrogen. Therefore, these monolayers have potential applications in photocatalytic materials or photoelectronic devices such as energy harvesters and visible-light sensors.

Energy Band Gap Investigation of Biomaterials: A Comprehensive Material Approach for Biocompatibility of Medical Electronic Devices

Over the past ten years, tissue engineering has witnessed significant technological and scientific advancements. Progress in both stem cell science and additive manufacturing have established new horizons in research and are poised to bring improvements in healthcare closer to reality. However, more sophisticated indications such as the scale-up fabrication of biological structures (e.g., human tissues and organs) still require standardization. To that end, biocompatible electronics may be helpful in the biofabrication process. Here, we report the results of our systematic exploration to seek biocompatible/degradable functional electronic materials that could be used for electronic device fabrications. We investigated the electronic properties of various biomaterials in terms of energy diagrams, and the energy band gaps of such materials were obtained using optical absorption spectroscopy. The main component of an electronic device is manufactured with semiconductor materials (i.e., Eg between 1 to 2.5 eV). Most biomaterials showed an optical absorption edge greater than 2.5 eV. For example, fibrinogen, glycerol, and gelatin showed values of 3.54, 3.02, and 3.0 eV, respectively. Meanwhile, a few materials used in the tissue engineering field were found to be semiconductors, such as the phenol red in cell culture media (1.96 eV energy band gap). The data from this research may be used to fabricate biocompatible/degradable electronic devices for medical applications.

The physical mechanism of electron excitation spectrum for photo redox device controlled by gate voltage, a first-principles study

This article uses quantum chemical methods and various wave function analysis methods to firstly analyze the optical absorption spectrum and electron migration mechanism of rhodamine 6G molecular complexes on graphene substrates during electron or hole injection. Secondly, since the light absorption properties are very important during photocatalysis, the intermolecular interaction and electronic structure in both cases were calculated and analyzed. Not only the experimental results of the previous photocatalytic devices were explained, but also the physical mechanism was promoted, and the guiding recommendations for the future catalytic device design.

Synthesis and Crystallographic, Absorption and Emission Studies of 4-Pyridine Carboxamide of Zn(II) 4-Chlorophenylacetate

A new zinc(II) complex, [Zn(CB)₂(INA)₂] (where CB is 4-chlorophenylacetate and INA is 4-pyridine carboxamide) was synthesized. The structure of the complex was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction technique. Besides, the thermal stability of the complex was investigated by TGA/DTA analysis method. Moreover, the optical absorption and the emission features of the complex were examined by using UV-Vis and fluorescence spectrophotometers, respectively. Furthermore, Density Functional Theory (DFT) calculations were carried out to support the experimental results. Accordingly, it was determined that the complex crystallized in a monoclinic system with space group Pc, a = 8.3329 (2) Å, b = 25.6530 (4) Å, c = 13.5048 (3) Å, α = 90°, β = 91.703 (3)° and γ = 90°. The complex consists two crystallographically independent molecules. In each molecule, the Zn^II ion adopts a distorted trigonal pyramidal coordination formed by two O atoms from the two 4 chlorophenylacetate ligand and two N atoms of the two 4-pyridine carboxamide ligands. It was observed that the linear absorption spectra of the complex were similar to linear absorption spectra of the semiconductors. In addition, two emission peaks were observed in the fluorescence spectra which could be due to the formation of excimer and the interactions of the benzene and pyridine rings. The energy gap (ΔE_gap = E_LUMO - E_HOMO) of the complex has been calculated as 3.712 eV and this value is very close to the experimentally measured value (3.86 eV). Therefore, because of higher fluorescence intensity of emission peak that was observed between 309 and 556 nm wavelength besides other traits, the complex could potentially be used in the blue light OLED application by filtering of the emission peak around 710 nm wavelength. Graphical Abstract It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. The fluorescence measurements showed that these materials are much suitable for application area of the detection of nitroaromatic explosives. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results. It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results.

Facile enhancement of bulk heterojunction solar cells performance by utilizing PbSe nanorods decorated with graphene

An efficient approach for improving the photoelectrical conversion efficiency (PCE) of the bulk heterojunction (BHJ) solar cells, based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁ butyric acidmethyl ester (PC₆₁BM), by incorporating PbSe nanorods decorated with graphene (G) into their active layer has been reported for the first time. Pristine PbSe and PbSe:G composites (with different amount of graphene) are synthesized via hydrothermal process and the formation mechanism is explained. The systematic investigation indicates that the crystallite size of PbSe:G increases with increasing graphene content. The PCE of the classical BHJ solar cells based on P3HT:PC₆₁BM is improved from 2.32 up to 2.57% by the incorporation of pristine PbSe. It is also enhanced by the incorporation of PbSe:G up to certain composition of graphene in which a maximum PCE value of 5.16% is achieved. The external quantum efficiency of the BHJ solar cells is also investigated. The photovoltaic parameters are discussed based on the morphology variation detected by scanning electron microscope and atomic force microscope of the active layers together with their UV-VIS absorption measurements.

Optical characterization of laser-driven double Morse quantum wells

In this study, the first-order linear, third-order nonlinear, and total absorption coefficients for the intersubband transition between the two lower-lying electronic levels in both symmetric and asymmetric double Morse quantum wells under the non-resonant high-frequency intense laser field are investigated. The study takes into account the effects of the structure parameters. The results show that the electronic and also accordingly optical properties of the structures which we focus on can be adjustable to obtain a convenient response to certain studies or purposes by changing the applied external field and optical intensity as well as structure parameters.

Theoretical insight on hybrid nanocomposites of graphene quantum dot and carbazole-carbazole dyes as an efficient sensitizer of DSSC

The feasibility of the hybrid nanocomposites of the graphene quantum dot (GQD) and carbazole-carbazole dyes as the efficient sensitizer of dye-sensitized solar cells (DSSC) is investigated. By using the first principles density functional theory (DFT), we fully optimize the geometrical structures of GQD, the carbazole-carbazole dyes, and their hybrid nanocomposites. The harmonic frequency analysis is used to confirm the energy stability of the optimized structures. The optical absorptions of the structures are calculated with the time-dependent DFT (TDDFT). Using the I^-/I₃^- electrolyte and the conduction band minimum of TiO₂ electrode as a sample, we examine the feasibility of the nanocomposites as the sensitizer of DSSC with the charge spatial separation and the molecular orbital energy levels of the nanocomposites. The results demonstrate all the considered nanocomposites have suitable energy levels of the frontier orbitals and significantly charge spatial separation. TDDFT results show the oscillator strengths of all nanocomposites demonstrate the obvious enhancement in the visible light region. Moreover, the appropriate open-circuit voltage value, the larger light-harvesting efficiency, and larger driving force are also identified for these nanocomposites. Therefore, the nanocomposites could be the more promising candidates of sensitizer for DSSC in comparison with the separate carbazole-carbazole dyes.

Theory and experiment of optical absorption of platinum nanoparticles synthesized by gamma radiation

Platinum nanoparticles were synthesized using the gamma radiolytic technique in an aqueous solution containing Platinum tetraammine chloride in presence of poly vinyl pyrrolidone, isopropanol, tetrahydrofuran and deionized water. The gamma irradiation was carried out in a⁶⁰Co gamma source chamber and the particle size was found to decrease from 4.88 to 3.14 nm on increasing the gamma radiation dose from 80 to 120 kGy. UV-visible absorption spectra were measured and revealed two steady absorption maxima at 216 and 264 nm in the UV region, which was blue shifted (i.e. toward lower wavelength) with decreasing particle size. By taking the conduction electrons of an isolated particle that are not entirely free, but instead bound to their respective quantum levels, the optical absorption of platinum nanoparticles can be calculated via intra-band quantum excitation for particle sizes similar to those measured experimentally. We found that the calculated absorption maxima of electronic excitations matched the measured absorption maxima well. This finding suggests that the optical absorption of metal nanoparticles commonly applied in nanoscience and nanotechnology can be described accurately by the quantum excitation of conduction electrons.

The puzzling optical-absorption and photoelectron spectra of neutral and anionic Ag8 clusters

The optical absorption and photoelectron spectra (PES) of neutral and anionic Ag₈ clusters have been studied using the particle-swarm optimization technique and time-dependent density functional theory. The results demonstrate that the enigmatic optical-absorption spectrum of neutral Ag₈ cluster is derived from the ground state structure with T_d symmetry rather than the almost degenerate isomer with D_2d symmetry. The transitions at 3.57-3.65 eV should be ascribed to the neutral fragment cluster Ag₇. Meantime, the optical-absorption and PES of neutral and anionic Ag₈ cluster are for the first time given a reasonable unified explanation.

Theoretical studies on the feasibility of the hybrid nanocomposites of graphene quantum dot and phenoxazine-based dyes as an efficient sensitizer for dye-sensitized solar cells

The feasibility of the hybrid nanocomposites of the graphene quantum dot (GQD) and the phenoxazine-based dyes as the efficient sensitizer of the dye-sensitized solar cell (DSSC) is investigated. Based on the first principles density functional theory (DFT), the geometrical structures of the separate GQDs, the phenoxazine-based dyes, and their hybridized nanocomposites are fully optimized. The energy stabilities of the obtained structures are confirmed by harmonic frequency analysis. The optical absorptions of the optimized structures are calculated with the time-dependent DFT (TDDFT). The feasibility of the nanocomposites as the sensitizer of DSSC is examined by the charge spatial separation, the molecular orbital energy levels of the nanocomposites and the I^-/I₃^- electrolyte, and the conduction band minimum of TiO₂ electrode. The results demonstrate that three of the eight considered nanocomposites satisfy the requirement of DSSC. Among them, GQD4-POXB with large LHE, high V_oc, and enhancement absorption becomes the most promising candidate as a feasible sensitizer. These findings are helpful for the design of the sensitizer of DSSC or the solar energy harvesting materials with the nanocomposites.

A flexible control on electromagnetic behaviors of graphene oligomer by tuning chemical potential

In this work, we demonstrate that the electromagnetic properties of graphene oligomer can be drastically modified by locally modifications of the chemical potentials. The chemical potential variations of different positions in graphene oligomer have different impacts on both extinction spectra and electromagnetic fields. The flexible tailoring of the localizations of the electromagnetic fields can be achieved by precisely adjusting the chemical potentials of the graphene nanodisks at corresponding positions. The proposed nanostructures in this work lead to the practical applications of graphene-based plasmonic devices such as nanosensing, light trapping and photodetection.

Theoretical studies on the possible sensitizers of DSSC: Nanocomposites of graphene quantum dot hybrid phthalocyanine/tetrabenzoporphyrin/tetrabenzotriazaporphyrins/cis-tetrabenzodiazaporphyrins/tetrabenzomonoazaporphyrins and their Cu-metallated macrocycles

The feasibility of nanocomposites of cir-coronene graphene quantum dot (GQD) with phthalocyanine, tetrabenzoporphyrin, tetrabenzotriazaporphyrins, cis-tetrabenzodiazaporphyrins, tetrabenzomonoazaporphyrins and their Cu-metallated macrocycles as a sensitizer of dye-sensitized solar cells (DSSC) are investigated. Based on the first principles density functional theory (DFT), the geometrical structures of the separate GQD and 10 macrocycles, and their hybridized nanocomposites are fully optimized. The energy stabilities of the obtained structures are confirmed by harmonic frequency analysis. The optical absorptions of the optimized structures are calculated with time-dependent DFT. The feasibility of the nanocomposites as the sensitizer of DSSC is examined by the charge spatial separation, the electron transfer, the molecular orbital energy levels of the nanocomposites and the electrolyte, and the conduction band minimum of TiO₂ electrode. The results demonstrate that all the nanocomposites have enhanced absorptions in the visible light range, and their molecular orbital energies satisfy the requirement of sensitizers. However, only two of the ten considered nanocomposites demonstrate significantly charge spatial separation. The GQD-Cu-TBP is identified as the most favorable candidate sensitizer of DSSC by the most enhanced in optical absorption, obvious charge spatial separation, suitable LUMO energy levels and driving force for electron transfer, and low recombination rate of electron and hole.

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

Recently, colored H-doped TiO₂ (H-TiO₂) has demonstrated enhanced photoelectrochemical (PEC) performance due to its unique crystalline core-disordered shell nanostructures and consequent enhanced conduction behaviors between the core-shell homo-interfaces. Although various hydrogenation approaches to obtain H-TiO₂ have been developed, such as high temperature hydrogen furnace tube annealing, high pressure hydrogen annealing, hydrogen-plasma assisted reaction, aluminum reduction and electrochemical reduction etc., there is still a lack of a hydrogenation approach in a controlled manner where all processing parameters (temperature, time and hydrogen flux) were precisely controlled in order to improve the PEC performance of H-TiO₂ and understand the physical insight of enhanced PEC performance. Here, we report for the first time a controlled and local rapid thermal annealing (RTA) approach to prepare hydrogenated core-shell H-TiO₂ nanorods grown on F:SnO₂ (FTO) substrate in order to address the degradation issue of FTO in the typical TiO₂ nanorods/FTO system observed in the conventional non-RTA treated approaches. Without the FTO degradation in the RTA approach, we systematically studied the intrinsic relationship between the annealing temperature, structural, optical, and photoelectrochemical properties in order to understand the role of the disordered shell on the improved photoelectrochemical behavior of H-TiO₂ nanorods. Our investigation shows that the improvement of PEC performance could be attributed to (i) band gap narrowing from 3.0 to 2.9 eV; (ii) improved optical absorption in the visible range induced by the three-dimensional (3D) morphology and rough surface of the disordered shell; (iii) increased proper donor density; (iv) enhanced electron-hole separation and injection efficiency due to the formation of disordered shell after hydrogenation. The RTA approach developed here can be used as a suitable hydrogenation process for TiO₂ nanorods/FTO system for important applications such as photocatalysis, hydrogen generation from water splitting and solar energy conversion.

Size-Controlled and Optical Properties of Platinum Nanoparticles by Gamma Radiolytic Synthesis

Gamma radiolytic synthesis was used to produce size-controlled spherical platinum nanoparticles from an aqueous solution containing platinum tetraammine and polyvinyl pyrrolidone. The structural characterizations were performed using X-ray diffraction, and transmission electron microscopy. The transmission electron microscopy was used to determine the average particle diameter, which decreased from 4.4nm at 80kGy to 2.8nm at 120kGy. The UV-visible absorption spectrum was measured and found that platinum nanoparticles exhibit two steady absorption maxima in UV regions due to plasmonic excitation of conduction electrons, which blue shifted to lower wavelengths with a decrease in particle size. We consider the conduction electrons of platinum nanoparticles to follow Thomas-Fermi-Dirac-Weizsacker atomic model that they are not entirely free but weakly bounded to particles at lower-energy states {n = 5, l = 2 or 5d} and {n = 6, l = 0 or 6s}, which upon receiving UV photon energy the electrons make intra-band quantum excitations to higher-energy states allowed by the principles of quantum number that results the absorption maxima. We found an excellent agreement between the experimental and theoretical results, which suggest that the optical absorption of metal nanoparticles could be fundamentally described by a quantum mechanical interpretation, which could be more relevant to photo-catalysis and heterogeneous catalysis.

Crystal structure, vibrational spectra, optical and DFT studies of bis (3-azaniumylpropyl) azanium pentachloroantimonate (III) chloride monohydrate (C6H20N3)SbCl5·Cl·H2O

The crystal structure of (C₆H₂₀N₃)SbCl₅·Cl·H₂O is built up of [NH₃(CH₂)₃NH₂(CH₂)₃NH₃]³⁺ cations, [SbCl₅]^2- anions, free Cl^- anions and neutral water molecules connected together by NH⋯Cl, NH⋯O and OH⋯Cl hydrogen bonds. The optical band gap determined by diffuse reflection spectroscopy (DRS) is 3.78eV for a direct allowed transition. Optimized molecular geometry, atomic Mulliken charges, harmonic vibrational frequencies, HOMO-LUMO and related molecular properties of the (C₆H₂₀N₃)SbCl₅·Cl·H₂O compound were calculated by Density functional theory (DFT) using B3LYP method with GenECP sets. The calculated structural parameters (bond lengths and angles) are in good agreement with the experimental XRD data. The vibrational unscaled wavenumbers were calculated and scaled by a proper scaling factor of 0.984. Acceptable consistency was observed between calculated and experimental results. The assignments of wavenumbers were made on the basis of potential energy distribution (PED) using Vibrational Energy Distribution Analysis (VEDA) software. The HOMO-LUMO study was extended to calculate various molecular parameters like ionization potential, electron affinity, global hardness, electro-chemical potential, electronegativity and global electrophilicity of the given molecule.

Eu3+ amidst ionic copper in glass: Enhancement through energy transfer from Cu+, or quenching by Cu2+?

A barium-phosphate glass system doped with europium(III) and containing a high concentration of copper(I) together with a copper(II) remnant has been studied spectroscopically. The main object is to elucidate whether the orange-red emission of Eu³⁺ ions succeeds through sensitization via luminescent Cu⁺ ions or else is preferentially quenched by non-radiative transfer to Cu²⁺. A characterization of the melt-quenched glass was first performed by UV/Vis optical absorption, ³¹P nuclear magnetic resonance and infrared absorption spectroscopy. A photoluminescence (PL) spectroscopy and emission decay dynamics assessment was subsequently performed. Despite the concentration of Cu⁺ being estimated to be much higher than that of Cu²⁺, the data shows that quenching of Eu³⁺ PL by Cu²⁺ dominates. The lifetime analysis of emitting centers Cu⁺ and Eu³⁺ points to the origin of the manifestation being that the Eu³⁺→Cu²⁺ non-radiative transfer rate responsible for the quenching is almost two times higher than that for the Cu⁺→Eu³⁺ transfer accountable for the enhancement. Finally, an effort was made for the determination of Cu²⁺ in the glass containing Cu⁺, Cu²⁺ and Eu³⁺ ions based on the Eu³⁺ (⁵D₀) emission decay rates. It was found to be in excellent agreement with the UV/Vis spectrophotometric approach, thus supporting the utility of Eu³⁺ ions for optical sensing of copper(II) in the solid state.

Optical, phonon and efficient visible and infrared photocatalytic activity of Cu doped ZnS micro crystals

We report, the enhanced photocatalytic behaviour of Cu doped ZnS micro crystals. ZnS and different concentrations of Cu doped ZnS microcrystals were prepared. X-ray diffraction confirms the crystalline and phase of the particles. Morphology and sizes were studied using Scanning Electron Microscopy (SEM). Recorded optical absorption spectra show a band for around 365nm for pure ZnS, but there is a broad band in the near infrared regime for the Cu-doped ZnS microcrystals which are attributed to the d-d transitions of Cu²⁺ ions. Phonon properties of as-prepared samples were investigated using Raman spectroscopy. Present work we investigate the potential of ZnS and Cu doped ZnS as a photocatalyst. For this from the degradation of methylene blue dye in aqueous media the photocatalytic activity of pure and highest doped ZnS samples with the irradiation of white light and infrared, enhanced photocatalytic activity were observed. Mechanism of white light an IR light based photocatalytic activity is explained based on the electron-hole pair production.

Structural, thermal and optical properties of TeO2-ZnO-CdO-BaO glasses doped with VO(2+)

The glasses with composition 64TeO2-15ZnO-(20-x)CdO-xBaO-1V2O5 (0⩽x⩽20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction analysis was used to confirm the amorphous nature of the glasses. The optical absorption studies revealed that the cut-off wavelength (λα) decreases while optical band gap energy (Eopt) and Urbach energy (ΔE) values increase with an increase of BaO content. Refractive index (n) evaluated from Eopt was found to decrease with an increase of BaO content. The physical parameters such as density (ρ), molar volume (Vm), oxygen packing density (OPD), optical basicity (Λ), molar refraction (Rm), and metallization criterion (M) evaluated and discussed. FTIR and Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg) of glass sample, onset crystallization temperature (To) and thermal stability ΔT were determined from Differential Scanning Calorimetry (DSC). Using electron paramagnetic resonance (EPR) spectra of vanadium glasses the spin Hamiltonian parameters and dipolar hyperfine coupling parameters of VO(2+) ions were calculated. It was found that V(4+) ions in these glasses exist as VO(2+) in octahedral coordination with a tetragonal distortion and have C4V symmetry with ground state dxy. Tetragonality (Δg∥/Δg⊥) of vanadium ion sites exhibited non-linear variation with BaO content.

Study of luminescence, color and paramagnetic centers properties of albite

A sample of natural albite, NaAlSi3O8, from the state of Minas Gerais, Brazil, has been investigated. The mineral is a solid solution of K-feldspar (4600 ppm--K) and Ca-feldspar (1100 ppm--Ca). The TL spectra of natural and the pre-annealed at high temperature albite presented a very intense band around 275 nm and weaker bands around 400 and 560 nm. Other TL properties have been investigated through monochromatic (275 nm and 400 nm) glow curves. The EPR spectrum measured at low temperature (77K) shows the typical 11 lines signal due to Al-O(-)-Al center superposed on Fe(3+) signal around g=2.0. The EPR spectra above 260 K show only g=2.0 signal due to Fe(3+) ions.

Crystal structure, vibrational studies, optical properties and DFT calculations of 2-amino-5-diethyl-aminopentanium tetrachlorocadmate (II)

Single crystals of a new organic-inorganic compound (C9H24N2) CdCl4 were grown by the slow evaporation technique and characterized by X-ray diffraction, infrared absorption Raman spectroscopy scattering, optical absorption, differential scanning calorimetry (DSC) analysis and dielectric measurements. The title compound belongs to the orthorhombic space group Pbca with the following unit cell parameters: a=11.397(7), b=13.843(4), c=22.678(5)Å and Z=8. In crystal structure, the tetrachlorocadmate anion is connected to organic cations through N-H⋯Cl hydrogen bonds. Theoretical calculations were performed using density functional theory (DFT) with the B3LYP/LanL2DZ level of theory for studying the molecular structure and vibrational spectra of the title compound. Good consistency is found between the calculated results and the experimental structure, IR, and Raman spectra. The detailed interpretation of the vibrational modes was carried out on the basis on our DFT calculations as primary source of assignment and by comparison with spectroscopic studies of similar compounds. The optical properties were investigated by optical absorption and show three bands at 300, 329 and 513 nm.

Spectroscopic studies of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione on plasmonic silver nanoparticles

Silver nanoparticles (Ag NPs) of different sizes from 7nm to 22nm have been prepared by simple Dirk and Charles chemical method and characterized using UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM). Fluorescence quenching of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione (DMDMAD) by silver nanoparticles has been investigated by fluorescence spectroscopy to understand the role of quenching mechanism. Furthermore, the intensity of DMDMAD fluorescence emission peak decreases with decrease in the size of the Ag NPs. The fluorescence quenching rate constant and association constant for above system were determined using Stern-Volmer and Benesi-Hildebrand plots. The mechanism of DMDMAD fluorescence quenched by Ag NPs was discussed according to the Stern-Volmer equation. It has been observed that the quenching due to Ag NPs proceeds via dynamic quenching process. The distance between DMDMAD (donor) to Ag NPs (acceptor) and the critical energy transfer distance were estimated based on the Förster Resonance Energy Transfer (FRET) theory.

Frequency domain optoacoustic tomography using amplitude and phase

We introduce optoacoustic tomographic imaging using intensity modulated light sources and collecting amplitude and phase information in the frequency domain. Imaging is performed at multiple modulation frequencies. The forward modeling uses the Green's function solution to the pressure wave equation in frequency domain and the resulting inverse problem is solved using regularized least squares minimization. We study the effect of the number of frequencies and of the bandwidth employed on the image quality achieved. The possibility of employing an all-frequency domain optoacoustic imaging for experimental measurements is studied as a function of noise. We conclude that frequency domain optoacoustic tomography may evolve to a practical experimental method using light intensity modulated sources, with advantages over time-domain optoacoustics.

Synthesis and microwave modification of CuO nanoparticles: crystallinity and morphological variations, catalysis, and gas sensing

CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles.

Effect of different fuels on structural, photo and thermo luminescence properties of solution combustion prepared Y(2)SiO(5) nanopowders

Y(2)SiO(5) nanopowders are prepared by solution combustion method using DFH, sugar and urea as fuels. The final product was well characterized by powder X-ray diffraction, Scanning Electron Microscopy and UV-Vis spectroscopy. The average crystallite size was estimated using Debye-Scherer's formula and Williamson-Hall plots and are found to be in the range 34-40nm for DFH, 45-50nm for urea and 35-42nm for sugar respectively. X1-X2 type YSO phase was obtained for all the samples calcined from 1200 to 1400°C. The optical energy band gaps (Eg) of the samples were estimated from Tauc relation and varies from 5.58 to 5.60eV. SEM micrographs of sugar and urea used Y(2)SiO(5) show agglomerated particles with porous morphology. However, for the sample prepared using DFH fuel observed to be almost spherical in shape. Thermoluminescence (TL) properties of γ-irradiated (1-5kGy) and UV irradiated (1-30min) Y(2)SiO(5) nanopowder at a heating rate of 2.5°Cs(-1) was studied. The samples prepared by using urea and sugar fuels show a broad TL glow peak at 189°C. However, DFH used Y(2)SiO(5) show a well resolved peak at 196°C with shouldered peak at 189°C. Among the fuels, DFH used Y(2)SiO(5) show simple glow peak structure which perhaps useful in radiation dosimetry. This may be due to fuel and particle size effect. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics are estimated by Chens glow peak shape method.

Synthesis, EPR and luminescent properties of YAlO3:Fe3+ (0.1-0.9mol%) nanopowders

A simple and inexpensive combustion method was used to prepare Fe(3+) doped YAlO3 perovskite within few minutes at low temperature (400±10°C). This might be useful in lowering the cost of the material. The final products were well characterized by various spectroscopic techniques such as PXRD, SEM, TEM, FTIR and UV-Visible. The average crystallite size was estimated from the broadening of the PXRD peaks and found to be in the range 45-90nm, the results were in good agreement with the W-H plots and TEM. The crystallites show dumbbell shape, agglomerated particles with different size. The TL glow curves of 1-5kGy γ-irradiated YAlO3:Fe(3+) (0.1mol%) nanopowder warmed at a heating rate of 3°Cs(-1) records a single glow peak at ∼260°C. The kinetic parameters namely activation energy (E), order of kinetics (b) and frequency factor (s) were determined at different gamma doses using the Chens glow peak shape method and the results were discussed in detail. The photoluminescence spectra for Fe(3+) (0.1-0.9mol%) doped YAlO3 records the lower energy band at 720nm ((4)T1 (4G)→(6)A1 (6S)) and the intermediate band located at 620nm ((4)T2 ((4)G)→(6)A1 (6S)) with the excitation of 378nm. The higher energy band located at 514nm was associated to (4)E+(4)A1 ((4)G)→(6)A1 (6S) transition. The resonance signals at g values 7.6, 4.97, 4.10, 2.94, 2.33 and 1.98 were observed in EPR spectra of Fe(3+) (0.1-0.9mol%) doped YAlO3 recorded at room temperature. The g values indicate that the iron ions were in trivalent state and distorted octahedral site symmetry was observed.

Structural, optical, electron paramagnetic, thermal and dielectric characterization of chalcopyrite

Chalcopyrite (CuFeS2) a variety of pyrite minerals was investigated through spectroscopic techniques and thermal analysis. The morphology and elemental analysis of the chalcopyrite have been done by high resolution SEM with EDAX. The lattice parameters were from the powder diffraction data (a=5.3003±0.0089 Å, c=10.3679±0.0289 Å; the volume of the unit cell=291.266 Å(3) with space group I42d (122)). The thermal decomposition behavior of chalcopyrite was studied by means of thermogravimetric analysis at three different heating rates 10, 15 and 20 °C/min. The values of effective activation energy (Ea), pre-exponential factor (ln A) for thermal decomposition have been measured at three different heating rates by employing Kissinger, Kim-Park and Flynn-Wall methods. Dielectric studies at different temperatures have also been carried out and it was found that both dielectric constant and dielectric loss decreases with the increase of frequency.

Crystal structure, vibrational studies, optical properties and DFT calculation of bis 2-aminobenzothiazolium tetrachloridocuprate

The zero dimensional organic-inorganic hybrid compound (C7H7N2S)2CuCl4 was synthesized and characterized by X-ray diffraction, infrared absorption, Raman spectroscopy scattering and optical transmission measurements. The title compound crystallizes in the monoclinic system with P21/c space group. The unit cell parameters are a=7.060 (5) Å, b=9.748 (5) Å, c=14.037 (5) Å, β=98.520 (5)° and Z=2. The copper (II) ion has square planar coordination environment and the structure is built up from isolated [CuCl4](2)(-) anion surrounded by organic cations connected together via N-H⋯Cl hydrogen bonding. Room temperature IR and Raman spectra of the title compound were recorded and analyzed. The theoretical geometrical parameters in the ground state have been investigated by density functional theory (DFT) with the B3LYP/LanL2DZ level of theory. The organic-inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C7H7N2S)2CuCl4 compound and it showed characteristic absorptions of Cu-Cl based layered perovskite centered at 288 and 400 nm.

Analytical one-dimensional model for laser-induced ultrasound in planar optically absorbing layer

Ultrasound generated by means of laser-based photoacoustic principles are in common use today and applications can be found both in biomedical diagnostics, non-destructive testing and materials characterisation. For certain measurement applications it could be beneficial to shape the generated ultrasound regarding spectral properties and temporal profile. To address this, we studied the generation and propagation of laser-induced ultrasound in a planar, layered structure. We derived an analytical expression for the induced pressure wave, including different physical and optical properties of each layer. A Laplace transform approach was employed in analytically solving the resulting set of photoacoustic wave equations. The results correspond to simulations and were compared to experimental results. To enable the comparison between recorded voltage from the experiments and the calculated pressure we employed a system identification procedure based on physical properties of the ultrasonic transducer to convert the calculated acoustic pressure to voltages. We found reasonable agreement between experimentally obtained voltages and the voltages determined from the calculated acoustic pressure, for the samples studied. The system identification procedure was found to be unstable, however, possibly from violations of material isotropy assumptions by film adhesives and coatings in the experiment. The presented analytical model can serve as a basis when addressing the inverse problem of shaping an acoustic pulse from absorption of a laser pulse in a planar layered structure of elastic materials.

Optical absorption of dilute nitride alloys using self-consistent Green's function method

We have calculated the optical absorption for InGaNAs and GaNSb using the band anticrossing (BAC) model and a self-consistent Green's function (SCGF) method. In the BAC model, we include the interaction of isolated and pair N levels with the host matrix conduction and valence bands. In the SCGF approach, we include a full distribution of N states, with non-parabolic conduction and light-hole bands, and parabolic heavy-hole and spin-split-off bands. The comparison with experiments shows that the first model accounts for many features of the absorption spectrum in InGaNAs; including the full distribution of N states improves this agreement. Our calculated absorption spectra for GaNSb alloys predict the band edges correctly but show more features than are seen experimentally. This suggests the presence of more disorder in GaNSb alloys in comparison with InGaNAs.

Synthesis, structural and luminescence studies of magnesium oxide nanopowder

Nanoparticles of magnesium oxide (MgO) have been prepared by low temperature solution combustion and hydrothermal method respectively. Powder X-ray diffraction (PXRD) patterns of MgO samples prepared by both the methods show cubic phase. The Scanning Electron Microscopy (SEM) studies reveal, the combustion derived product show highly porous, foamy and fluffy in nature than hydrothermally derived sample. The optical absorption studies of MgO show surface defects in the range 250-300 nm. The absorption peak at ∼290 nm might be due to F-centre. Photoluminescence (PL) studies were carried upon exciting at 290 nm. The sample prepared via combustion method show broad emission peak centred at ∼395 nm in the bluish-violet (3.14 eV) region. However, in hydrothermal prepared sample show the emission peaks at 395 and 475 nm. These emission peaks were due to surface defects present in the sample since nanoparticles exhibits large surface to volume ratio and quantum confinement effect.

Spectroscopic characterization of manganese minerals

Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals.

A review on electronic and optical properties of silicon nanowire and its different growth techniques

Electronic and optical properties of Silicon Nanowire (SiNW) obtained from theoretical studies and experimental approaches have been reviewed. The diameter dependency of bandgap and effective mass of SiNW for various terminations have been presented. Optical absorption of SiNW and nanocone has been compared for different angle of incidences. SiNW shows greater absorption with large range of wavelength and higher range of angle of incidence. Reflectance of SiNW is less than 5% over majority of the spectrum from the UV to near IR region. Thereafter, a brief description of the different growth techniques of SiNW is given. The advantages and disadvantages of the different catalyst materials for SiNW growth are discussed at length. Furthermore, three thermodynamic aspects of SiNW growth via the vapor-liquid-solid mechanism are presented and discussed.

The quenching effect of silver nanoparticles on 2-amino-3-bromo-1, 4-naphthoquinone using fluorescence spectroscopy

Nanoparticles of noble metals belong to the most extensively studied colloidal systems in the field of nanoscience and nanotechnology. Silver nanoparticles of different sizes have been prepared with the chemical reduction method using sodium borohydride and characterized using optical absorption technique. Using optical absorption and fluorescence emission studies, the photo physical properties of 2-amino-3-bromo1, 4-naphthoquinone (ABNQ) on silver nanoparticle have been studied. Concentration of the silver nanoparticle has been evaluated and the particle size dependent interaction between silver nanoparticles and ABNQ has been studied. The fluorescence quantum yield of ABNQ with and without silver nanoparticles has been calculated. The Stern-Volmer quenching constants and the molar absorptivity have been evaluated.

MgO:Eu3+ red nanophosphor: low temperature synthesis and photoluminescence properties

Nanoparticles of Eu(3+) doped (0-9 mol%) MgO were prepared using low temperature (400°C) solution combustion technique with metal nitrate as precursor and glycine as fuel. The powder X-ray diffraction (PXRD) patterns of the as-formed products show single cubic phase and no further calcination was required. The crystallite size was obtained using Scherer's formula and was found to be 5-6 nm. The effect of Eu(3+) ions on luminescence characteristics of MgO was studied and the results were discussed in detail. These phosphors exhibit bright red emission upon 395 nm excitation. The characteristic photoluminescence (PL) emission peaks at ∼580, 596, 616, 653, 696 and 706 nm ((5)D0→(7)Fj=0, 1, 2, 3, 4) were recorded due to Eu(3+) ions. The electronic transition corresponding to (5)D0→(7)F2 of Eu(3+) ions (616 nm) was stronger than the magnetic dipole transition corresponding to (5)D0→(7)F1 of Eu(3+) ions (596 nm). The international commission on illumination (CIE) chromaticity co-ordinates were calculated from emission spectra, the values (x, y) were very close to national television system committee (NTSC) standard value of red emission. Therefore the present phosphor was highly useful for display applications.

Synthesis, structural and optical properties of ZnO and Ni-doped ZnO hexagonal nanorods by Co-precipitation method

Ni doped ZnO (Zn1-xNixO, x=0.0, 0.03, 0.06 and 0.09) nanorods have been synthesized by Co-precipitation method. Zinc acetate dehydrate [Zn(CH3COO)2⋅2H2O], nickel nitrate [Ni(NO3)3⋅6H2O], sodium hydroxide and poly (vinyl pyrrolidone) (PVP) were mixed together. The morphology, optical and microstructure were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive spectrum (EDS), atomic force microscopy (AFM), UV-DRS spectrum, photoluminescence spectra (PL) and Fourier transformer infrared spectroscopy (FT-IR). The presence of functional groups and chemical bonding is confirmed by FTIR. PL spectra of the Zn1-xNixO systems shows that the shift in near band edge (NBE) UV emission from 321 to 322 nm and a shift in red band (RB) emission from 620 to 631 nm which conforms the substitution of Ni into the ZnO lattice. The investigation conformed that the products were of the wurtzite structure of ZnO. The hexagonal nanorods have edge length 31 nm and thickness of 39 nm. EDS result showed that the amount of Ni in the product is about 9%, these Ni doped hexagonal nanorods exhibits a blue shifts and weak (UV) emission peak, compared with pure ZnO, which may be induced by the Ni-doping different concentrations 0.0, 0.3, 0.6 and 0.9 M. The growth mechanism of the doped hexagonal nanorods was also discussed.

Interaction of Schiff base ligand with tin dioxide nanoparticles: optical studies

Interaction between 1,4 Bis ((2-Methyl) thio) Phenylamino methyl benzene (BMTPMB) Schiff base with tin dioxide nanoparticles (SnO2 NPs) of various concentrations in methanol have been studied using UV-Visible and Fluorescence spectroscopic techniques. The low value of Stern-Volmer quenching constant and non-linear plot of Benesi-Hildebrand equation suggests the less affinity of SnO2 NPs towards the adsorption of BMTPMB Schiff base. The Scott equation has been employed to determine molar absorptivity of the Schiff base-NPs system.

SU-F-BRCD-08: Uncertainty Quantification by Generalized Polynomial Chaos for MR-Guided Laser Induced Thermal Therapy

PURPOSE

Magnetic resonance-guided laser induced thermal therapy (MRgLITT) is a minimally invasive thermal treatment for metastatic brain lesions, offering an alternative to conventional surgery. The purpose of this investigation is to incorporate uncertainty quantification (UQ) into the biothermal parameters used in the Pennes bioheat transfer equation (BHT), in order to account for imprecise values available in the literature. The BHT is a partial differential equation commonly used in thermal therapy models.

METHODS

MRgLITT was performed on an in vivo canine brain in a previous investigation. The canine MRgLITT was modeled using the BHT. The BHT has four parameters'" microperfusion, conductivity, optical absorption, and optical scattering'"which lack precise measurements in living brain and tumor. The uncertainties in the parameters were expressed as probability distribution functions derived from literature values. A univariate generalized polynomial chaos (gPC) expansion was applied to the stochastic BHT. The gPC approach to UQ provides a novel methodology to calculate spatio-temporal voxel-wise means and variances of the predicted temperature distributions. The performance of the gPC predictions were evaluated retrospectively by comparison with MR thermal imaging (MRTI) acquired during the MRgLITT procedure in the canine model. The comparison was evaluated with root mean square difference (RMSD), isotherm contours, spatial profiles, and z-tests.

RESULTS

The peak RMSD was ∼1.5 standard deviations for microperfusion, conductivity, and optical absorption, while optical scattering was ∼2.2 standard deviations. Isotherm contours and spatial profiles of the simulation's predicted mean plus or minus two standard deviations demonstrate the MRTI temperature was enclosed by the model's isotherm confidence interval predictions. An a = 0.01 z-test demonstrates agreement.

CONCLUSIONS

The application of gPC for UQ is a potentially powerful means for providing predictive simulations despite poorly known input parameters. gPC provides an output that represents the probable distribution of outcomes for MRgLITT.