Changes In Relative Intensities Research Articles

Simultaneous detection of atmospheric HONO and NO<sub>2</sub> utilising an IBBCEAS system based on an iterative algorithm

Abstract. We present an improved incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) system based on an iterative retrieval algorithm for the simultaneous detection of atmospheric nitrous acid (HONO) and nitrogen dioxide (NO2). The conventional IBBCEAS retrieval algorithm depends on the absolute change in the light intensity, which requires high light source stability and the stable transmission of the light intensity of all optical components. The new algorithm has an iterative module to obtain the effective absorption optical path length, and the concentrations of HONO and NO2 are then determined by differential optical absorption spectroscopy (DOAS) retrieval; thus, the method is insensitive to the fluctuation in the absolute light intensity. The robustness of the system is verified by simulating the influence of the relative change in the light intensity on the spectral retrieval results. The effect of nitrogen purging in front of the cavity mirrors on shortening the actual cavity length was measured and corrected using NO2 gas samples. Allan deviation analysis was conducted to determine the system stability, and it indicated that the detection limits (2σ) of HONO and NO2 are 0.08 and 0.14 ppbv at an integration time of 60 s respectively. Furthermore, Kalman filtering was used to improve the measurement precision of the system. The measurement precision at an integration time of 3 s can be improved 4.5-fold by applying Kalman filtering, which is equivalent to the measurement precision at an integration time of 60 s without applying Kalman filtering. The atmospheric HONO and NO2 concentrations were observed by the IBBCEAS system based on an iterative algorithm and were compared with values measured by conventional IBBCEAS.

Reflection Absorption Infrared Spectroscopy Characterization of SAM Formation from 8-Mercapto-N-(phenethyl)octanamide Thiols with Phe Ring and Amide Groups.

Multifunctional amide-containing self-assembled monolayers (SAMs) provide prospects for the construction of interfaces with required physicochemical properties and distinctive stability. In this study, we report the synthesis of amide-containing thiols with terminal phenylalanine (Phe) ring functionality (HS(CH2)7CONH(CH2)2C6H5) and the characterization of the formation of SAMs from these thiols on gold by reflection absorption infrared spectroscopy (RAIRS). For reliable assignments of vibrational bands, ring deuterated analogs were synthesized and studied as well. Adsorption time induced changes in Amide-II band frequency and relative intensity of Amide-II/Amide-I bands revealed two-state sigmoidal form dependence with a transition inflection points at 2.2 ± 0.5 and 4.7 ± 0.5 min, respectively. The transition from initial (disordered) to final (hydrogen-bonded, ordered) structure resulted in increased Amide-II frequency from 1548 to 1557 cm−1, which is diagnostic for a strongly hydrogen-bonded amide network in trans conformation. However, the lateral interactions between the alkyl chains were found to be somewhat reduced when compared with well-ordered alkane thiol monolayers.

(Invited) Near Infrared Optical Probes for Imaging Neuromodulators with High Spatiotemporal Resolution

Dopamine neurotransmission plays critical roles in brain function in both health and disease and aberrations in dopamine neurotransmission are implicated in several psychiatric and neurological disorders, including schizophrenia, depression, anxiety, and Parkinson’s disease. Until recently, measuring the dynamics of dopamine and other neurotransmitters of this class could not be achieved at spatiotemporal resolutions necessary to understand how dopamine regulates the plasticity and function of neurons and neural circuits, and how dysfunctions in this regulation lead to disease. Probes that satisfy critical attributes in spatial and temporal resolution, and chemical selectivity are needed to facilitate investigations of brain neurochemistry.To address this need, we developed an ultrasensitive near-infrared “turn-on” nanosensor (nIRCat) for the catecholamines dopamine and norepinephrine and implemented nIRCat to study endogenous dopamine dynamics in brain tissue. nIRCats are synthesized from photostable and near infrared emissive functionalized single wall carbon nanotubes (SWCNT) and exhibit maximal relative change in fluorescence intensity (ΔF/F0) of up to 35-fold, with a dynamic range that spans physiological concentrations of their target brain analytes. We demonstrate that nIRCat can detect electrically and optogenetically evoked release of dopamine in brain tissue, revealing putative hotspots of activity that exhibited a log-normal distribution in size, ranging from 2 – 10 µm for mice brain tissue in the dorsomedial striatum. Furthermore, the synthetic nature of the molecular recognition platform afforded compatibility with dopamine-receptor targeting antipsychotics and psychoactive drugs and permitted studies of how such receptor-targeting drugs modulate evoked dopamine release. This assay revealed presynaptic correlates of drug activity at the level of putative dopamine release sites, which had heretofore been inaccessible to probe with existing tools. Our results suggest that nIRCat technology may uniquely support similar explorations of processes that regulate dopamine neuromodulation at the level of individual synapses, and exploration of the effects of receptor agonists and antagonists that are commonly used as psychiatric drugs as well as drugs that lead to substance use disorder. We conclude that SWCNTs can serve as versatile synthetic optical scaffolds for monitoring interneuronal chemical signaling in the brain extracellular space at spatial and temporal scales pertinent with the encoded neurochemical information.

Metal-Organic Framework-Plant Nanobiohybrids as Living Sensors for On-Site Environmental Pollutant Detection.

Photoluminescent metal-organic frameworks (MOFs) were grown in a living plant (Syngonium podophyllum) via immersing their roots in an aqueous solution of disodium terephthalate and terbium chloride hexahydrate sequentially for 12 h without affecting their viability. Then, app-assisted living MOF-plant nanobiohybrids were used for the detection of various toxic metal ions and organic pollutants. Their performance and sensing mechanism were also evaluated. The results demonstrated that the living plants served as self-powered preconcentrators via their passive fluid transport systems and accumulated the pollutants around the embedded MOFs, resulting in relative changes in fluorescence intensity. Therefore, the living MOF-plant nanobiohybrids initiate superior selectivity and sensitivity (0.05-0.5 μM) in water for Ag+, Cd2+, and aniline with a "turn-up" fluorescence response and for Fe3+ and Cu2+ with "turn-down" fluorescence response in the linear range of 0.05-10 μM with excellent precision and accuracy of 5 and 10%, respectively. With the easy-to-read visual signals under ultraviolet light, the app translates plant luminescent signals into digital information on a smartphone for on-site monitoring of environmental pollutants with high sensitivity and specificity. These results suggest that interfacing synthetic and living materials may contribute to the development of smart sensors for on-site environmental pollutant sensing with high accuracy.

Dose-Dependent Radiation-Induced Myocardial Damage in Esophageal Cancer Treated With Chemoradiotherapy: A Prospective Cardiac Magnetic Resonance Imaging Study

PurposeThe purpose of this prospective study was to evaluate radiation-induced myocardial damage after mediastinal radiation therapy (RT) using late gadolinium-enhancement (LGE) magnetic resonance imaging (MRI). Methods and MaterialsWe enrolled 19 patients with esophageal cancer who were expected to have long-term survival by definitive treatment. They underwent delayed contrast-enhanced MRI (19 patients before treatment, 19 patients 6 months after treatment, and 12 patients 1.5 years after treatment). Dose distribution of the left ventricle was made using computed tomography, and the dose volume histogram of the left ventricle was calculated. Myocardial signal intensities in individual MRIs were normalized by the mean values in regions receiving low doses (<5 Gy). Changes in the normalized signal intensities after mediastinal radiation therapy were compared among regions where irradiation doses were 0 to 10 Gy, 10 to 20 Gy, 20 to 30 Gy, 30 to 40 Gy, 40 to 50 Gy, and 50 to 60 Gy, and we investigated whether intensity change was detected in a dose-dependent manner. ResultsThe registered patients were treated with concurrent chemoradiotherapy with a median total dose of 60 Gy (50.4-66 Gy). Chemotherapy consisting of cisplatin and 5-fluorouracil was administered. In the population-based dose-response curve, dose-dependent intensity changes progressively increased in regions receiving more than 30 Gy. The averages of relative intensity change at 6 months and 1.5 years after treatment were 1.1% and −1.9% at 20 to 30 Gy and 37.5% and 17.5% at 40 to 50 Gy, respectively. LGE in regions receiving more than 30 Gy was detected in 68% (13/19) of the patients. ConclusionsA dose-dependent relationship for myocardial signal intensity change was found by using LGE MRI. It may be necessary to reduce the volume of the myocardium receiving more than 30 Gy.

Extrusions do not affect degenerative morphologic changes in lateral meniscus allografts during midterm follow-ups.

To investigate degenerative morphological changes in meniscus allograft after lateral meniscus allograft transplantation (MAT) based on extrusions. Ninety-one patients who underwent lateral MAT were divided into extruded and non-extruded groups. Serial magnetic resonance imaging scans obtained 6weeks, 1year, and at the last follow-up (midterm, 3-7years) post-surgery were evaluated retrospectively. Degenerative morphological changes at each time point in each group were compared using the postoperative meniscal width, thickness, and intrameniscal signal intensity (IMSI) at the anterior horn, mid-body, and posterior horn. The Lysholm scores and meniscal tears based on graft extrusion were also investigated. The mean age was 33.7 ± 11.1years (64 men and 27 women). Fifty-three (58%) and 38 knees (42%) were classified into the non-extruded and extruded groups, respectively. The overall meniscal width of the mid-body decreased from 9.6 ± 1.3 to 6.5 ± 1.2mm (p < 0.01), and IMSI of mid-body was increased from 1.2 ± 0.1 to 1.7 ± 0.1 (p < 0.01) during midterm follow-ups. No significant differences were observed between the meniscal width, thickness, and IMSI at the anterior horn (n.s.), mid-body (n.s.), and posterior horn (n.s.) of the two groups during the midterm follow-ups. The incidence of meniscus tears and Lysholm scores did not differ significantly between the groups during midterm follow-ups. The overall meniscus width of mid-body decreased while the relative IMSI of mid-body increased during midterm follow-ups after lateral MAT. Meniscal allograft extrusions did not influence postoperative changes in meniscus width, thickness, and relative intrameniscal signal intensity. Level III.

Coherent phonon dynamics in a c-plane sapphire crystal before and after intense femtosecond laser irradiation.

Femtosecond pump-probe experiments with a ∼6.4 fs time-resolution were performed to investigate the coherent phonon dynamics in a c-plane sapphire crystal before and after intense 800 nm femtosecond laser irradiation. The intense femtosecond laser induced defect/distortion and even re-crystallization of crystalline structures, which result in the appearance of new peaks and relative intensity change in coherent phonon and Raman spectra. The combination of these two spectra was found to be beneficial to evidence the variation of crystalline structure and further to differentiate the origins of new Raman peaks after irradiation. Further analysis of time-dependent differential absorbance with damped cosine function fitting and Fourier transfer calculation yields the vibrational parameters, including periods, damping times and initial phases, before and after irradiation. With these parameters, the defect-effects on damping time and the mechanism of coherent phonon generation were addressed.

(Invited) Near-Infrared Optical Probes for Imaging Neuromodulators with High Spatiotemporal Resolution

Dopamine neurotransmission plays critical roles in brain function in both health and disease and aberrations in dopamine neurotransmission are implicated in several psychiatric and neurological disorders, including schizophrenia, depression, anxiety, and Parkinson’s disease. Until recently, measuring the dynamics of dopamine and other neurotransmitters of this class could not be achieved at spatiotemporal resolutions necessary to understand how dopamine regulates the plasticity and function of neurons and neural circuits, and how dysfunctions in this regulation lead to disease. Probes that satisfy critical attributes in spatial and temporal resolution, and chemical selectivity are needed to facilitate investigations of brain neurochemistry.To address this need, we developed an ultrasensitive near-infrared “turn-on” nanosensor (nIRCat) for the catecholamines dopamine and norepinephrine and implemented nIRCat to study endogenous dopamine dynamics in brain tissue. nIRCats are synthesized from photostable and near infrared emissive functionalized single wall carbon nanotubes (SWCNT) and exhibit maximal relative change in fluorescence intensity (ΔF/F0) of up to 35-fold, with a dynamic range that spans physiological concentrations of their target brain analytes. We demonstrate that nIRCat can detect electrically and optogenetically evoked release of dopamine in brain tissue, revealing putative hotspots of activity that exhibited a log-normal distribution in size, ranging from 2 – 10 µm for mice brain tissue in the dorsomedial striatum. Furthermore, the synthetic nature of the molecular recognition platform afforded compatibility with dopamine-receptor targeting antipsychotics and psychoactive drugs and permitted studies of how such receptor-targeting drugs modulate evoked dopamine release. This assay revealed presynaptic correlates of drug activity at the level of putative dopamine release sites, which had heretofore been inaccessible to probe with existing tools. Our results suggest that nIRCat technology may uniquely support similar explorations of processes that regulate dopamine neuromodulation at the level of individual synapses, and exploration of the effects of receptor agonists and antagonists that are commonly used as psychiatric drugs as well as drugs that lead to substance use disorder. We conclude that SWCNTs can serve as versatile synthetic optical scaffolds for monitoring interneuronal chemical signaling in the brain extracellular space at spatial and temporal scales pertinent with the encoded neurochemical information.

Graphene-enhanced Raman scattering on single layer and bilayers of pristine and hydrogenated graphene

Graphene-enhanced Raman scattering (GERS) on isotopically labelled bilayer and a single layer of pristine and partially hydrogenated graphene has been studied. The hydrogenated graphene sample showed a change in relative intensities of Raman bands of Rhodamine 6 G (R6G) with different vibrational energies deposited on a single layer and bilayer graphene. The change corresponds qualitatively to different doping of graphene in both areas. Pristine graphene sample exhibited no difference in doping nor relative intensities of R6G Raman peaks in the single layer and bilayer areas. Therefore, it was concluded that strain and strain inhomogeneities do not affect the GERS. Because of analyzing relative intensities of selected peaks of the R6G probe molecules, it is possible to obtain these results without determining the enhancement factor and without assuming homogeneous coverage of the molecules. Furthermore, we tested the approach on copper phtalocyanine molecules.

Pressure dependence of vibrational optical activity of model biomolecules. A computational study.

Change of molecular properties with pressure is an attracting means to regulate molecular reactivity or biological activity. However, the effect is usually small and so far explored rather scarcely. To obtain a deeper insight and estimate the sensitivity of vibrational optical activity spectra to pressure-induced conformational changes, we investigate small model molecules. The Ala-Ala dipeptide, isomaltose disaccharide and adenine-uracil dinucleotide were chosen to represent three different biomolecular classes. The pressure effects were modeled by molecular dynamics and density functional theory simulations. The dinucleotide was found to be the most sensitive to the pressure, whereas for the disaccharide the smallest changes are predicted. Pressure-induced relative intensity changes in vibrational circular dichroism and Raman optical activity spectra are predicted to be 2-3-times larger than for non-polarized IR and Raman techniques.

Weak Interaction of Ni-Doped SnO2 Powder Materials with Sodium Benzenesulfonate Homologues as Templates

The tin oxide and the nickel-doped tin oxide photocatalyst were successfully prepared by the simple solid-state reaction among SnCl4·5H2O, NiCl2·6H2O and NaOH using sodium benzenesulfonate homologues as templates. The samples were characterized by X-ray powder diffraction (XRD), UV–Vis absorption spectra (UV–Vis), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption. The weak interaction between Ni2+ and templates in the reaction system was quantified, and the photodegradation properties of puerarin on the materials were estimated. The results show that Ni2+ enters the (110) crystal plane of SnO2, producing lattice distortion, as well as, the relative diffraction intensity (I101/ I110) change of the (101) and (110) crystal plane. And it squats in the lattice in the form of Ni2+ and Ni3+ to produce impurity energy levels, which reduces the band gap width (△Eg) of SnO2 from 3.4 to 3.02 eV. The weak interaction between surfactants and precursors (Ni2+ ions) is mainly derived from the steric hindrances of the sodium benzenesulfonate homologues of the size of the substituted groups, and the induction effect of Ni2+ ions. Wherein, the steric hindrance of surfactants plays a leading role, while the induction of Ni2+ ions plays a secondary role, the contribution of the steric resistance effect of ethyl and methyl for surfactants EBSS, STS to lattice mismatch is 0.23% and 0.14%, respectively, that is, the steric hindrance effect of methyl is only ~ 60% of that of ethyl. The greater the steric hindrance of the surfactants, the higher the lattice mismatch rate, the relative diffraction intensity (I101/I110), the oxygen defect concentration and the ratio of Ni2+/ Ni3+, the stronger the photodegradation ability of Ni–SnO2-EBSS material to puerarin is. In 50 min, the degradation rate of puerarin solution with initial concentration of 20 mg/L is 99.1%.

Raman, DRIFT and ATR-IR spectra, corrosion inhibition, DFT and solid-state calculations of 4-amino-3-choloro-2,5,6-trifluoropyridine

The Raman spectrum (3700-100 cm−1) of 4-Amino-3-choloro-2,5,6-trifluoro-pyridine (ACTFP; C5H2ClF3N2) has been recorded in the solid phase using 514.5 nm (green) and 785 nm (red) lasers to trace relative intensity changes. Moreover, the ATR-IR (4000-500 cm−1) and DRIFT (4000–400 cm−1) spectra of the solid were also recorded. Nine structures were suggested for ACTFP based on amino-imino tautomerism in addition to suggested conformers as a result of amino group internal rotation. DFT-B3LYP calculations at basis sets up to 6–311++G(d,p) favor the non-planaramino form (S-1; C1 symmetry), possessing the least energy with real vibrational frequencies. Based on X-ray single crystals and owing to the observed four stretches for NH2 moiety, the presence of two molecules per unit cell (a dimer molecule) is also investigated using both Gaussian B3LYP/at 6-31G(d) and CASTEP solid state computations. Reliable vibrational assignments were proposed herein based on estimated wavenumbers, normal coordinate analyses (NCA), potential energy distributions (PEDs) and de-convoluted spectra. Nevertheless, the NCA were found to be extensively mixed, all C–F and C–Cl fundamentals were confidently allocated herein, however were not considered in earlier published data of similar molecules. Moreover, frontier molecular orbitals (HOMO and LUMO) and atomic charge distributions (NPA and ESP) were also predicted for ACTFP to examine its efficiency as a corrosion inhibitor.

Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream

Photochemical processing is an important way to transform terrestrial dissolved organic matter (DOM) but was rarely investigated by ultra-high resolution mass spectrometry. We performed an irradiation experiment with water from a shaded forest stream flowing into a lit reservoir. Bacterial activity explained only 1% of dissolved organic carbon (DOC) decline in a combined bacterial and photodegradation approach. Photodegradation decreased the DOC concentration by 30%, the specific ultraviolet (UV) absorption by 40%–50%, and fluorescence intensity by 80% during six days. The humification index (HIX) decreased whereas the fluorescence index (FI) did not change. Two humic-like components identified by parallel factor analysis (PARAFAC) of excitation–emission matrices followed the decrease of fluorescent DOM. Changes of relative peak intensities of Fourier transform-ion cyclotron resonance mass spectroscopy (FT-ICR MS) elemental formula components as a function of cumulated radiation were evaluated both by Spearman’s rank correlation and linear regression. The FT-ICR MS intensity changes indicate that high aromatic material was photochemically converted into smaller non-fluorescent molecules or degraded by the release of CO2. This study shows the molecular change of terrestrial DOM before the preparation of drinking water from reservoirs.

Effect of Pyridine on the Structure and Vibrations of Cobalt Phthalocyanine

Abstract Effect of pyridine on cobalt phthalocyanine (CoPc) has been studied by the density functional theory and Raman spectroscopy. Thermal evaporation method has been used for the preparation of a thin film of CoPc and then Raman spectra of CoPc film have been recorded with and without exposure of pyridine. The molecular structure of CoPc and its coordinated complexes with pyridine have been computed using B3LYP/6-31(d,p) level of density functional theory calculations by employing Gaussian program package. Calculations show some in-plane and out-of-plane distortions in the structure of CoPc. Some noticeable changes have been observed in the Raman spectrum of CoPc thin film after its exposure with pyridine. Changes in wavenumbers and relative intensities of some of the bands have been observed. Most of the observed bands show downward shifts in the wavenumbers. These changes, are attributed to the weakening of some bonds and change of symmetry of CoPc, and confirm the coordination of pyridine molecule(s) with CoPc molecule

Colloidal (Gd0.98Nd0.02)2O3 nanothermometers operating in a cell culture medium within the first and second biological windows

Non-contact, self-referenced and near-infrared luminescent nanothermometers have been recognized as emerging tools in the fields of nanomedicine and nanotechnology due to their great capability of precise temperature readout at the nanoscale and real-time deep-tissue imaging. However, the development of multifunctional and biocompatible luminescent nanothermometers operating within the optically transparent biological windows with high thermal sensitivity (>2.0%/K) remains challenging. Here, we present (Gd0.98Nd0.02)2O3 nanothermometers operated effectively within the first and second biological windows upon continuous-wave laser diode excitation at 808 nm. Ratiometric thermometric parameters are defined by the relative changes in the emission intensities originating from the two Stark components of the 4F3/2 level (R2 and R1) to the 4I9/2 (900–1000 nm), 4I11/2 (1035–1155 nm) and 4I13/2 (1300–1450 nm) multiplets. The thermometric parameters are evaluated for colloidal samples in a cell culture medium and powder samples, and the highest thermal sensitivity (2.18%/K at 298 K) is attained for the former in the first biological window (both the excitation and emission in the 800–965 nm range). The repeatability and temperature uncertainty are 99% and 1.2 K, respectively. The nanothermometers are biocompatible with human MNT-1 melanoma and HaCaT cells for 24 h of exposure and nanoparticle concentration up to 0.400 mg/mL, showing their potential for applications in nanomedicine, e.g., intracellular imaging and temperature mapping.

Tailoring light-matter interaction in WS2 –gold nanoparticles hybrid systems

Recently, considerable attention has been paid to tune the emission using hybrid systems composed of layered transition-metal dichalcogenides and metal nanoparticles (NPs) since metal NPs have the ability to enhance and localize the incident electromagnetic field. Furthermore, these hybrid systems show great interest from the standpoint of fundamental science as it constitutes an atomic scale prototype of charge-transfer complexes. Here, we realized ${\mathrm{WS}}_{2}$--gold (Au) NPs hybrids by chemically growing Au NPs at the edges of the mechanically exfoliated bilayer ${\mathrm{WS}}_{2}$. The Au NPs significantly increase the light-matter interaction which has been studied through Raman and photoluminescence (PL) spectroscopy. A substantial enhancement of the PL intensity in the ${\mathrm{WS}}_{2}$--Au composite concerning the pristine ${\mathrm{WS}}_{2}$ has been observed, and it increases as the number and size of the Au NPs on ${\mathrm{WS}}_{2}$ is increased. Geometry-dependent modification of plasmon resonance energy of Au NP alters the coupling strength between the emission pathways of ${\mathrm{WS}}_{2}$ and the plasmon which is manifested by a change in relative intensity between trion $({X}^{\ensuremath{-}})$ and exciton $(X)$ emissions. We probe the mechanism of the PL intensity modulation through polarization-dependent measurements and simulation. We have demonstrated that, in ${\mathrm{WS}}_{2}$, the internal quantum efficiency increases and activation energy decreases due to coupling with Au NPs. Compared to pristine ${\mathrm{WS}}_{2}$, a faster change in optical band gap with temperature in ${\mathrm{WS}}_{2}$--Au may be due to enhancing electron-phonon interaction and lattice expansion in the latter. Our paper indicates the possibility to develop high performance transition-metal dichalcogenide-based photonic devices.

Structural, electric and dielectric properties of Ni0.5Zn0.5FeCoO4 ferrite prepared by sol-gel

Ni0.5Zn0.5FeCoO4 spinel ferrite was elaborated using sol-gel technique. X-ray diffraction patterns indicate that sample has a cubic spinel type structure with Fd-3m space group. The change in Raman modes and relative intensity were observed due to ball milling and consequently to the decrease of particle size and cationic redistribution. The Raman spectra show peaks appearing at 450 and 490 cm−1 corresponding to T2g (2) and T2g (3), respectively. It may be noted that both of these modes shift toward the higher wavenumber with the substitution of Zn by Ni in Ni0.5Zn0.5FeCoO4 ferrite. Mössbauer spectroscopy analysis shows one tetrahedral A-site and two octahedral B-sites. Due to Zn doping, the hyperfine magnetic fields are much smaller than for CoFe2O4 and NiFe2O4 ferrites. The Jonscher’s power low was used to describe the ac-conductivity measurements. Frequency dependence of dielectric constant (ε″) and tangent loss (tan) display a dispersive behavior at low frequencies that can be explained by the Maxwell Wagner model and Koop's theory. Electric modulus formalism has used to study the relaxation dynamics of charge carriers. The complex impedance spectra (Nyquist plots) show well-defined semicircles which are strongly dependent on the temperature.

Characterization for the transformation of dissolved organic matters during ultraviolet disinfection by differential absorbance spectroscopy.

The transformation of dissolved organic matter (DOM) during various disinfection processes has raised great concerns due to the generation of carcinogenic disinfection by-products (DBPs). Ultraviolet (UV) irradiation is an effective method for drinking water disinfection, during which DOM undergoes changes in functional groups and molecular weight. In this study, the spectrophotometric titration and gel permeation chromatography (GPC) determination were employed to investigate the changes in oxygenated groups and weight-averaged molecular weight (Mw) of two typical DOM during UV irradiation. The differential absorbance spectra (DAS) of DOM could be deconvoluted into six Gaussian bands. The change of relative band intensity was attributed to the change of oxygenated groups (carboxylic and phenolic groups), which was confirmed by combining DAS data and revised Non-Ideal Competitive Adsorption -Donnan model. The GPC result demonstrated that the Mw of DOM decreased after UV disinfection. Moreover, a linear correlation between Mw and the intensity of deconvoluted Gaussian band from DAS was established, which might be served as an alternative approach to estimate Mw and predict the hydrophobicity and DBPs formation potential of DOM in drinking water treatment and monitoring.

SFFS–SVM based prostate carcinoma diagnosis in DCE-MRI via ACM segmentation

The prostate carcinoma is amongst the most commonly occurring cancers in Taiwanese males. Moreover, it is one of the chief reasons for cancer deaths among Taiwanese men, and early diagnosis of prostate cancer is vital for effective treatment. In this work, a diagnosis model for identifying the prostate carcinoma in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is proposed. The urologists utilize the DCE-MRI as a support mechanism for better diagnosis of the carcinoma development in the prostate. Gadolinium is utilized as the contrast agent for the DCE-MRI data, and it was injected once and the time series data were captured at distinct time intervals of 0, 20, 60, and 100 s correspondingly. Primarily, after pre-processing the DCE-MRI information, the prostate data is segmented by employing the active contour model. Subsequently, 136 features are extracted from the segmented prostrate expanse of the DCE-MRI data, and the relative intensity change curve is computed. Afterward, Fisher’s discriminant ratio and sequential forward floating selection is deployed for choosing ten highly discriminative features. Lastly, the segmented prostate regions are classified into two groups, namely: tumor and normal classes by employing the support vector machine classifier. The experimental results elucidate that the proposed system is superior on the subject of accuracy, sensitivity, and specificity when compared with specific existing methods. Additionally, the proposed system also demonstrates a 94.75% accuracy. Moreover, this signifies the fact that the proposed method for analyzing the DCE data has shown prodigious prospects in the prostate carcinoma diagnosis.

G-protein-coupled receptor 40 agonist GW9508 potentiates glucose-stimulated insulin secretion through activation of protein kinase Cα and ε in INS-1 cells.

ObjectiveThe mechanism by which G-protein-coupled receptor 40 (GPR40) signaling amplifies glucose-stimulated insulin secretion through activation of protein kinase C (PKC) is unknown. We examined whether a GPR40 agonist, GW9508, could stimulate conventional and novel isoforms of PKC at two glucose concentrations (3 mM and 20 mM) in INS-1D cells.MethodsUsing epifluorescence microscopy, we monitored relative changes in the cytosolic fluorescence intensity of Fura2 as a marker of change in intracellular Ca2+ ([Ca2+]i) and relative increases in green fluorescent protein (GFP)-tagged myristoylated alanine-rich C kinase substrate (MARCKS-GFP) as a marker of PKC activation in response to GW9508 at 3 mM and 20 mM glucose. To assess the activation of the two PKC isoforms, relative increases in membrane fluorescence intensity of PKCα-GFP and PKCε-GFP were measured by total internal reflection fluorescence microscopy. Specific inhibitors of each PKC isotype were constructed and synthesized as peptide fusions with the third α-helix of the homeodomain of Antennapedia.ResultsAt 3 mM glucose, GW9508 induced sustained MARCKS-GFP translocation to the cytosol, irrespective of changes in [Ca2+]i. At 20 mM glucose, GW9508 induced sustained MARCKS-GFP translocation but also transient translocation that followed sharp increases in [Ca2+]i. Although PKCα translocation was rarely observed, PKCε translocation to the plasma membrane was sustained by GW9508 at 3 mM glucose. At 20 mM glucose, GW9508 induced transient translocation of PKCα and sustained translocation as well as transient translocation of PKCε. While the inhibitors (75 μM) of each PKC isotype reduced GW9508-potentiated, glucose-stimulated insulin secretion in INS-1D cells, the PKCε inhibitor had a more potent effect.ConclusionGW9508 activated PKCε but not PKCα at a substimulatory concentration of glucose. Both PKC isotypes were activated at a stimulatory concentration of glucose and contributed to glucose-stimulated insulin secretion in insulin-producing cells.