Changes In Relative Intensities Research Articles

Vibrational spectroscopic study of poly(dimethylsiloxane)-ZnO nanocomposites

A series of poly(dimethylsiloxane)-zinc oxide (PDMS-ZnO) nanocomposites having different concentrations of ZnO nanoparticles (0, 1, 5, 10 and 20wt%) have been prepared. Raman and FTIR-ATR spectroscopic analysis was performed in order to determine the interaction between the ZnO nanoparticles and PDMS polymer matrix. Density functional theory (DFT) using the (B3-LYP)/6-311++G(2df,2p) method was used to investigate the vibrational spectra of PDMS. A complete vibrational assignment is supported by the normal coordinate analysis, calculated Raman activities as well as IR intensities.The presence of ZnO nanoparticles in PDMS gives rise to significant differences in relative intensities of the characteristic vibrational bands with respect to the cross-linked polymer. The changes in relative intensities of Raman bands, as well as swelling measurements, were used to explain the effect of ZnO nanoparticles on the cross-linked structure of PDMS nanocomposites. It is established that ZnO nanoparticles influence the cross-linking density of the polymer matrix.

Diel Vertical Migration in Deep Sea Plankton Is Finely Tuned to Latitudinal and Seasonal Day Length

Diel vertical migration (DVM) is a ubiquitous phenomenon in marine and freshwater plankton communities. Most commonly, plankton migrate to surface waters at dusk and return to deeper waters at dawn. Up until recently, it was thought that DVM was triggered by a relative change in visible light intensity. However, evidence has shown that DVM also occurs in the deep sea where no direct and background sunlight penetrates. To identify whether such DVM is associated with latitudinal and seasonal day light variation, one and a half years of recorded acoustic data, a measure of zooplankton abundance and movement, were examined. Acoustic Doppler current profilers, moored at eight different sub-tropical latitudes in the North-Atlantic Ocean, measured in the vertical range of 500–1600 m. DVM was observed to follow day length variation with a change in season and latitude at all depths. DVM followed the rhythm of local sunrise and sunset precisely between 500 and 650 m. It continued below 650 m, where the deepest penetrable irradiance level are <10−7 times their near-surface values, but plankton shortened their time at depth by up to about 63% at 1600 m. This suggests light was no longer a cue for DVM. This trend stayed consistent both across latitudes and between the different seasons. It is hypothesized that another mechanism, rather than light, viz. a precise biochemical clock could maintain the solar diurnal and seasonal rhythms in deep sea plankton motions. In accordance with this hypothesis, the deepest plankton were consistently the first to migrate upwards.

Localisation of adenine nucleotides in heat-stabilised mouse brains using ion mobility enabled MALDI imaging

Information regarding the energetic state of tissue is important in a wide range of experimental fields, particularly in the study of metabolic stress, such as hypoxia or ischaemia. Metabolic stress leads to the degradation of adenine nucleotides in brain tissue, but little is known about any changes in the relative spatial distribution of these molecules. Ion mobility enabled MALDI imaging mass spectrometry has been employed to investigate the localisation of the adenine nucleotides ATP, ADP and AMP in mouse brain. The aim of the work is to develop a reproducible method for detecting changes in localisation and relative intensity of these nucleotides after metabolic stress. We demonstrate improved selectivity when ion mobility separation for the identification and localisation of the adenine nucleotides in tissue is employed. Tissue fixation methods have been evaluated to overcome rapid post-mortem degradation of adenine nucleotides such that biologically relevant localisation images can be obtained. These studies highlight the crucial importance of appropriate biological sample presentation in MALDI imaging experiments.

Raman microspectroscopy and vibrational sum frequency generation spectroscopy as probes of the bulk and surface compositions of size-resolved sea spray aerosol particles

Sea spray aerosol (SSA) represents one of the largest aerosol components in our atmosphere. SSA plays a major role in influencing climate; however the overall impacts remain poorly understood due to the overall chemical complexity. SSA is comprised of a mixture of inorganic and organic components in varying proportions that change as a function of particle size and seawater composition. In this study, nascent SSA particles were produced using breaking waves, resulting in compositions and sizes representative of the open ocean. The composition of individual SSA particles ranging in size from ca. 0.15 to 10 μm is measured using Raman microspectroscopy, while the interfacial composition of collections of size-resolved particles is probed by sum frequency generation (SFG). Raman spectra of single particles have bands in the 980 to 1030 cm(-1) region associated with the symmetric stretch of the sulfate anion, the 2800 to 3000 cm(-1) region associated with carbon-hydrogen stretches, and from 3200-3700 cm(-1) associated with the oxygen-hydrogen stretches of water. The relative intensities of these features showed a strong dependence on particle size. In particular, submicrometer particles exhibited a larger amount of organic matter compared to supermicrometer particles. However, for external surfaces of homogeneous SSA particles (i.e. particles without a solid inclusion), and also the interfaces of mixed-phase particles, there was a strong SFG response in the aliphatic C-H stretching region for both sub- and supermicrometer particles. This finding suggests that organic material present in supermicrometer particles primarily resides at the interface. The presence of methylene contributions in the SFG spectra indicated disordered alkyl chains, in contrast to what one might expect for a surfactant layer on a sea salt particle. Changes in peak frequencies and relative intensities in the C-H stretching region are seen for some particles after the addition of bacteria, phytoplankton, and growth medium to the seawater. This study provides new insights into the bulk and surface composition of SSA particles and represents a step forward in our understanding of this globally abundant aerosol. It also provides insights into the development of model systems for SSA that may more accurately represent the organic layer at the surface.

The Neurospora photoreceptor VIVID exerts negative and positive control on light sensing to achieve adaptation

The light response in Neurospora is mediated by the photoreceptor and circadian transcription factor White Collar Complex (WCC). The expression rate of the WCC target genes adapts in daylight and remains refractory to moonlight, despite the extraordinary light sensitivity of the WCC. To explain this photoadaptation, feedback inhibition by the WCC interaction partner VIVID (VVD) has been invoked. Here we show through data-driven mathematical modeling that VVD allows Neurospora to detect relative changes in light intensity. To achieve this behavior, VVD acts as an inhibitor of WCC-driven gene expression and, at the same time, as a positive regulator that maintains the responsiveness of the photosystem. Our data indicate that this paradoxical function is realized by a futile cycle that involves the light-induced sequestration of active WCC by VVD and the replenishment of the activatable WCC pool through the decay of the photoactivated state. Our quantitative study uncovers a novel network motif for achieving sensory adaptation and defines a core input module of the circadian clock in Neurospora.

基于等离子体光谱特征的空气中激光铁块清洗的研究

The intensities of emission spectra of rusty iron plasma induced by Nd:YAG pluse laser,were experimentally studied in air atmosphere. Modified ME5000 echelle grating spectrometer coupled to intensified CCD camera was used to acquire the emission spectrum of laser-induced Fe plasma under the laser shock.The experimental results indicated that continuous laser impacts with certain energy were required to induce the Fe emission spectrum due to the existence of the impurities in the sample.The relative intensities of plasma spectra increased obviously after the impurities were decomposed during the process of laser shock.With the comparison of spectra acquired under 1st laser shock and in the cleaning process,it was shown that when the intensity of the characteristic line at the wavelength of 563.40nm increased by443.11%,the rusty iron was cleaned and the cleaning-ratio reached 99.84%.At the same time,the fluctuation of the spectrum decreased obviously during the cleaning.As a result,the changes of spectrum distribution and relative intensity of Fe spectrum lines could be used to judge whether the samples were cleaned or not through an analysis of the spectrum lines under 1st laser shock and those in the cleaning process.

Effects of hydrogen-bond and cooperativity in the vibrational spectra of Luminol

Luminol, one of the most popular electrochemiluminescence systems used in forensic chemistry, proved to be a suitable system to study the importance of cooperativity in hydrogen-bond chains. The computational pairwise approach PiMM was applied to the system and a thorough band assignment was accomplished. Hydrogen-bond and hydrogen-bond cooperativity effects were assessed through a confrontation of energy, geometry and wavenumber changes from monomer and dimer on one hand and dimer and “full-cluster” trimer on the other. For the first time the PiMM method was also used to successfully predict changes in band relative intensities.

Effect of Al dopant concentration on structural, optical and photoconducting properties in nanostructured zinc oxide thin films

Thin films of undoped and doped ZnO, with different Al concentrations (1–5wt%) were deposited onto glass substrates, by the sol–gel spin coating method. Grazing incidence X-ray diffraction (GIXRD) studies confirmed the nature of films as poly-crystalline, with typical hexagonal wurtzite structure. The films showed variation in crystallite size and change in relative intensities, upon different Al doping concentrations. The surface morphology of the films examined using FE-SEM, showed the grain size becoming smaller upon Al doping. The influence of Al with different concentrations, onto ZnO on the optical absorption and transmittance was studied using UV–Vis–NIR spectrophotometer in the wavelength range 300–2500nm. The UV absorption shifted towards shorter wavelength upon Al doping. The average transmittance in the visible region increased for Al doped films up to 1–2wt% and decreased for other concentration. The dark and photo conductivity measurements of the films indicated increase in the current values upon doping up to 1–2wt% of Al and decreased for further concentrations. The rise and decay time measured from the photoresponse study, indicate larger values of rise time for the doped films compared to undoped ZnO. However, the film with 1–2wt% doping of Al showed better response within the doping concentration. The thermal activation energy obtained from temperature-dependant conductivity showed decrease in the value upon Al doping up to 2wt% and increased beyond this concentration in the temperature range 300–400K.

The origin of fluorescence from graphene oxide.

Time-resolved fluorescence measurements of graphene oxide in water show multiexponential decay kinetics ranging from 1 ps to 2 ns. Electron-hole recombination from the bottom of the conduction band and nearby localized states to wide-range valance band is suggested as origin of the fluorescence. Excitation wavelength dependence of the fluorescence was caused by relative intensity changes of few emission species. By introducing the molecular orbital concept, the dominant fluorescence was found to originate from the electronic transitions among/between the non-oxidized carbon regions and the boundary of oxidized carbon atom regions, where all three kinds of functionalized groups C-O, C = O and O = C-OH were participating. In the visible spectral range, the ultrafast fluorescence of graphene oxide was observed for the first time.

Electron excitation of the valence subshell in potassium at low impact energies

Near-threshold excitation of the 3p6nl levels in potassium has been studied by measuring the "conventional" electron energy-loss spectrum and the near-threshold, constant residual energy-loss spectrum. The data were obtained at an incident energy resolution of 0.07 eV and an observation angle of 90°. Drastic changes in relative intensity of peaks when impact energy approaches the excitation threshold may denote the important role of resonance processes in excitation of the lowest np, ns and nd levels.

Impaired emotion processing from vocal and facial cues in frontotemporal dementia compared to right hemisphere stroke

To advance our understanding about the emotional and cognitive deficits of patients with frontotemporal dementia with behavioral variant (bvFTD), the current study examined comprehension and expression of emotions from prosodic and facial cues in a 66-year-old woman. The patient diagnosed with bvFTD is compared to six patients with acute right hemisphere stroke. Recognition of emotion from prosodic cues was assessed using an identification task in four conditions with decreasing verbal demands (neutral sentences, language-like pseudo sentences, monosyllables, and asyllabic vowel sounds). Repetition of utterances with emotional connotations and self-generated conversations were analyzed to measure relative changes in mean fundamental frequency (f0), f0 variance, speech rate, and intensity along with the facial musculature pattern. The patient showed a marked deficit in identifying emotions in all four prosody conditions; and she did not show much variation in modulating mean f0, f0 variance, speech rate and intensity for all emotion categories when compared to neutral utterances. In addition, this patient demonstrated little to no facial expressions during emotionally provoking tasks, but demonstrated no difficulty recognizing emotions from facial expressions or verbal scenarios. Results show that the patient seems to have selective impairment in recognition of emotions from prosody and expression of emotions using both prosodic and facial features. Impaired processing of emotional prosody and facial expressions could be important for detecting bvFTD with greater right hemisphere atrophy.

Physico-chemical studies of new luminescent chemosensor for Cu2+

The spectroscopic properties of (E)-2-(2-hydroxybenzylideneamino)-3-phenylpropanoic acid (HBDPPA) has been studied in a series of different solvents. As revealed by absorbance, and emission results, the molecule undergoes fast excited-state intramolecular proton transfer (ESIPT) to yield emission of the corresponding tautomeric species. A large energy barrier for interconversion of the keto-enol rotamers in the ground and excited state have been predicted on the basis of DFT calculations and also supported by HOMO–LUMO energies, PES calculation, NLO and NBO analysis. Hyperpolarizability and octupolar and dipolar components ratio confirmed that HBDPPA can be used as optoelectronic materials. The ground state equilibrium and ESIPT process of HBDPPA are essentially unaffected by the nature of the solvent. Measurements of absorption solvatochromism have been interpreted with Marcus and Reichardt–Dimroth solvent functions to estimate the transition dipoles. Good correlation exists between absorption as well as fluorescence wavenumbers obtained by the multi-component linear regression employing the Taft and Catalan solvent parameters with the experimental values. The prepared Schiff base HBDPPA can be used as a new fluorescent sensor to detect the quantity of Cu2+ ion in any sample solution depending on the relative intensity change.

Economic impact measurement and evaluation of China's investment in geological exploration: The empirical analysis based on the data from 1999 to 2009

With the continued growth in demand for mineral resources and China's efforts in increasing investment in geological prospecting, economic impact evaluation of geological exploration becomes a research hotspot.In this paper, CES production function model is applied to measure the economic impact of geological survey at the industry level. The results suggest that the synergistic contribution of central & local fiscal investments and social capital is significant to the price of mining rights. The most dramatic impact is from social capital, and the next, the impact from local fiscal investment. The central fiscal funds play an important role to link up investments in different prospecting stages and to share the risk. When the relative intensity changes between central fiscal and local fiscal, central fiscal and social capital, local fiscal and social capital in the logarithm square at 1 unit, the price of mining rights has 2.065, 1.359 and 0.178 times the positive long-term effects, respectively.Comparing the different economic impacts of geological survey investment in the eastern, western and central district of China, describing the social capital's pulling effect into geological survey & mining industry and the unit cost trends of the geological survey investment on typical minerals, the research indicates that overall economic outcome of geological exploration is obvious from the four angles of industry and regional output, the capital pulling and the cost management.

Photoluminescence of Europium-Activated Hydroxyapatite Nanoparticles in Body Fluids

Hydroxyapatite (Ca10(PO4� 6(OH)2, HA) nanoparticles activated with Eu 3+ were synthesized using the sol–gel technique. The crystal structure was elucidated by X-ray diffraction analysis and the internal crystal structure and morphology was studied by transmission electron microscopy. Under excitation with 394 nm light, the powders are red-emitting. The photoluminescence bands are detected at 575 nm ( 5 D0 → 7 F0), ∼590 nm ( 5 D0 → 7 F1), 613 nm ( 5 D0 → 7 F2) and 626 nm ( 5 D0 → 7 F2). The nanosized HA:Eu dispersed in urine and blood serum showed high stability with respect to their optical properties, although some transitions underwent a change in relative emission intensities. A change in emission intensities was also observed for the cysteine dispersion. The stability at different pHs was studied in water and urine fluids. The HA:Eu nanoparticles are suitable as biomarkers for nanomedical applications.

DFT based ESIPT process of luminescent chemosensor: Taft and Catalan solvatochromism

Amino acid containing o-hydroxy Schiff base derivative was synthesized and an excited state intramolecular proton transfer (ESIPT) process in o-hydroxy Schiff base (HBMBA) has been studied using solution spectral studies. It was detected that the two distinct ground state isomers I and II are responsible for the emission. By comparing the emission wavelength in hydrocarbon solvent, it was predicted that the trans enol form predominates over the cis enol form. DFT calculations on energy, dipole moment, charge distribution of the rotamers in the ground and excited states of the Schiff base derivative were performed and discussed. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than in the ground state. The fluorescence of HBMBA quenched with the gradual addition of Cu2+. Therefore the prepared Schiff base HBMBA can be used as a new fluorescent sensor to detect the quantity of Cu2+ ions in any sample solution depending on the relative intensity change. Measurements of absorption solvatochromism have been interpreted with Marcus and Reichardt–Dimroth solvent functions to estimate the transition dipoles. Good correlation exists between absorption as well as fluorescence wavenumbers obtained by the multi-component linear regression employing the Taft and Catalan solvent parameters with the experimental values.

Water-Sensitive High-Frequency Molecular Vibrations in Self-Assembled Diphenylalanine Nanotubes

High-frequency molecular vibrations in bio- inspired peptide nanostructures provide insight into the important interactions between peptides and water molecules. Raman spectra acquired from diphenylalanine (FF) nanotubes show that water bonded weakly to FF molecules in the nanochannel cores leads to splitting of the molecular vibrational mode of benzene rings at 1034 cm −1 into a doublet with the separation diminishing with decreasing water content. X-ray diffraction discloses that loss of water results in noticeable lattice expansion in the subnanometer crystalline structure comprising hexagonal unit cells, and derivation based on the density functional theory shows that the Raman-active phonon modes often appear in pairs due to the duality of the major components in the FF molecules. Without water, the two typical peaks in the vicinity of 1034 cm −1 from the vibrations of two benzene rings in the FF molecule are very close and usually cannot be distinguished experimentally, but with the addition of water, the two peaks are gradually separated and the relative intensities change. Our results demonstrate that Raman scattering can be used to probe the quantity of water molecules in FF NTs via the linear dependence of the Raman mode position at the low-frequency side of the double-peak mode at 1034 cm −1 on water molecule number bonded to each FF molecule. This knowledge is important to the fundamental understanding of the interactions between FF nanotubes and water, device design, as well as applications to biochemistry, medicine, and molecular sensing.

MR T1ρ as an imaging biomarker for monitoring liver injury progression and regression: an experimental study in rats with carbon tetrachloride intoxication

Recently it was shown that the magnetic resonance imaging (MRI) T1ρ value increased with the severity of liver fibrosis in rats with bile duct ligation. Using a rat carbon tetrachloride (CCl(4)) liver injury model, this study further investigated the merit of T1ρ relaxation for liver fibrosis evaluation. Male Sprague-Dawley rats received intraperitoneal injection of 2 ml/kg CCl(4) twice weekly for up to 6 weeks. Then CCl(4) was withdrawn and the animals were allowed to recover. Liver T1ρ MRI and conventional T2-weighted images were acquired. Animals underwent MRI at baseline and at 2 days, 2 weeks, 4 weeks and 6 weeks post CCl(4) injection, and they were also examined at 1 week and 4 weeks post CCl(4) withdrawal. Liver histology was also sampled at these time points. Liver T1ρ values increased slightly, though significantly, on day 2, and then increased further and were highest at week 6 post CCl(4) insults. The relative liver signal intensity change on T2-weighted images followed a different time course compared with that of T1ρ. Liver T1ρ values decreased upon the withdrawal of the CCl(4) insult. Histology confirmed the animals had typical CCl(4) liver injury and fibrosis progression and regression processes. MR T1ρ imaging can monitor CCl(4)-induced liver injury and fibrosis. • MR T1ρ is a valuable imaging biomarker for liver injury/fibrosis. • Liver T1ρ was only mildly affected by oedema and acute inflammation. • Liver MR T1ρ decreased when liver fibrosis and injury regressed.

Rotational excitation of simple polar molecules by H2and electrons in diffuse clouds

[This is truncated to suit the whims of the archivers ...] Parameter studies in LVG models are used to show how the low-lying rotational transitions of common polar molecules HCO+, HCN and CS vary with number density, column density and electron fraction; with molecular properties such as the charge state and permanent dipole moment; and with observational details such as the transition that is observed. Physically-based models are used to check the parameter studies and provide a basis for relating the few extant observations. The parameter studies of LVG radiative transfer models show that lines of polar molecules are uniformly brighter for ions, for lower J-values and for higher dipole moments. Excitation by electrons is more important for J=1-0 lines and contributes rather less to the brightness of CS J=2-1 lines. If abundances are like those seen in absorption, the HCO+ J=1-0 line will be the brightest line after CO, followed by HCN (1-0) and CS (2-1). Because of the very weak rotational excitation in diffuse clouds, emission brightnesses and molecular column densities retain a nearly-linear proportionality under fixed physical conditions, even when transitions are quite optically thick; this implies that changes in relative intensities among different species can be used to infer changes in their relative abundances.

Nanoscale Plasmonic Interferometers for Multispectral, High-Throughput Biochemical Sensing

In this work, we report the design, fabrication, and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form two-arm, three-beam, planar plasmonic interferometers. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400-800 nm). A wavelength sensitivity between 370 and 630 nm/RIU (RIU, refractive index units), a relative intensity change between ~10(3) and 10(6) %/RIU, and a resolution of ~3 × 10(-7) in refractive index change were experimentally measured using typical sensing volumes as low as 20 fL. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time, and extremely compact biochemical sensors.

How Do Industries and Firms Respond to Changes in Local Labor Supply?

This paper analyzes how changes in the skill mix of local labor supply are absorbed by the economy, distinguishing between three adjustment mechanisms: wages, expansion in size of those production units using the more abundant skill group more intensively, and more intensive use of the more abundant skill group within production units. We contribute to the literature by analyzing these adjustments on the firm rather than industry level, using German administrative data. We show that most adjustments occur within firms through changes in relative factor intensities and that firms entering and exiting the market are an important additional absorption mechanism.