Intensity Of Characteristic Peaks Research Articles

Highly ordered pure and indium-incorporated MCM-41 mesoporous adsorbents: synthesis, characterization and evaluation for dye removal

Highly ordered pure MCM-41 and In-MCM-41 mesoporous adsorbents (with Si/In = 95 (IM0.05) and Si/In = 90 (IM0.1)) were synthesized using the hydrothermal-assisted method. The structural, morphological and texture characteristics were investigated by XRD, N2 adsorption–desorption, SEM-EDX, TEM, diffuse reflectance (DR) and FTIR. The broadening XRD diffraction peaks as well as the shifts to higher and lower 2-theta in IM0.05 and IM0.1, respectively, confirmed the incorporation of indium atoms in the MCM-41 structure. SEM-EXD and TEM images showed that pure MCM-41 and IM0.05 preserve a highly long-range well-ordered hexagonal pore structure, on the other hand, high loading of indium (IM0.1) resulted in partially irregular pore-ordering and morphological defects related to a partial dissolution of MCM-41 structure. The infrared spectra of In-incorporated samples showed a decrease in the transmittance intensity of MCM-41 characteristic peaks with little shifts relative to the pure MCM-41 sample. The potential of pure MCM-41 and In-MCM-41 samples for adsorption of dyes was preliminarily investigated. The removal efficiency of both methylene blue and basic yellow-28 (BY28) was enhanced by the incorporation of indium in the MCM-41. The adsorption equilibrium data of BY28 dye on pure, IM0.05 and IM0.1 samples fitted well with Langmuir adsorption model with adsorption capacity of 123.46, 156.99 and 158.48 mg g−1 respectively. The calculated free adsorption energy obtained from D–R isotherm was found to be 26.7 kJ mol−1 referring to that the adsorption of BY28 on IM0.05 adsorbent is chemical. The adsorption kinetic of BY28 on IM0.05 sample followed the pseudo-second-order model. The adsorption experiments revealed that the prepared samples can be used as effective adsorbents for the removal of dyes in aqueous solutions with good recovery and recyclability.Graphical

Rapid and Sensitive Detection of Pentachloronitrobenzene by Surface-Enhanced Raman Spectroscopy Combined with Molecularly Imprinted Polymers.

Molecularly imprinted polymers (MIPs) specifically targeting pentachloronitrobenzene (PCNB) and containing silver nanoparticles have been prepared by free radical polymerization reaction using methyl methacrylate (MMA) as a functional monomer, PCNB as a template molecule, 1,4-butanedioldimethacrylate as a cross linker, lauroyl peroxide (LPO) as an initiator, and the silver nanoparticles with the best surface-enhanced Raman scattering (SERS) effect as SERS enhancement materials. Our results indicated that MIPs specifically recognize PCNB from complex matrices. The intensity of the PCNB characteristic peak was proportional to the concentration, with a linear range of 0.005 to 0.15 μg/mL and a limit of detection of 5.0 ng/mL. The recovery rates and relative standard deviation for the detection of PCNB spiked in the rice samples were from 94.4% to 103.3% and from 4.6% to 7.4%, respectively. The experimental results are consistent with those by the GC-MS method, indicating that the rapid detection of PCNB in food matrices by SERS-MIPs is reliable. In view of the insolubility of PCNB in water, oil-soluble silver nanoparticles were synthesized which can be expanded to detect oil-soluble toxic substances. For the first time, the proposed method provides a point-of-care and cost-effective tool for rapidly detecting PCNB in food matrices with high sensitivity and selectivity by employing SERS-MIPs method.

Steady/transient state spectral researches on the solvent-triggered and photo-induced novel properties of metal-coordinated phthalocyanines.

The large conjugated system and the d orbitals of metallic phthalocyanines (MPcs) are easily triggered by solvent molecules and light to cause variations in photo-physical and photo-chemical properties. To clarify the novel properties of photo-excited MPcs in solvents, the steady/transient state spectral data were collected to investigate four MPc templates, including FePc, ZnPc, CoPc and AlClPc. The Q bands of FePc and CoPc were prone to redshift, while the peaks of ZnPc and AlClPc tended to blueshift in various solvents compared with that in DMSO. With xenon lamp irradiation, the characteristic absorption peak intensity of FePc and ZnPc in DMSO decreased gradually and then increased after being subjected to dark condition. The transient absorption spectra and kinetic data illustrated that photo-excited FePc and CoPc produced relatively short lifetime transient intermediates. The positive absorption at 650 nm in the Q bands of FePc and CoPc could be assigned to the d–π* electron transition in transient intermediates with unpaired d-orbital electron in the open shell configuration of Fe2+ and Co2+. The above studies were of great significance for the application of solvent-triggered and photo-induced novel properties of MPcs.

Extraction of mannoprotein from Saccharomyces cerevisiae and analysis of its chemical composition and molecular structure

The purpose of this study was to screen the method with the highest yield of mannoprotein (MP) without damaging their functional structure. The recovery rates of the extracts, protein, and mannose were determined along with the mannose/protein ratio, molecular weight and distribution, monosaccharide and amino acid compositions, and secondary structures of the three MP extracts to compare the extraction methods. The MP extracts recovery rate prepared by the thermal method was significantly higher (35.89%) than those obtained using fermentation (31.66%) and SDS treatment (19.77%). Three protein bands with similar molecular weights of 59, 47, and 34 kDa were detected in the MPs obtained via the different extraction methods. The thermally extracted MP has a broader molecular weight distribution. After purification, the proportion of mannose in the polysaccharide parts of the MPs increased from 6–7 to 90.4–91.3%. The essential amino acid content of the hot-extracted MP (170.07 mg/g) was the highest. The thermally extracted MP had similar secondary structural characteristics to that isolated at room temperature, and had a higher protein characteristic peak intensity. In general, the heating method to extract yeast mannoprotein is time-saving and efficient.

Label-free identification of lung cancer cells from blood cells based on surface-enhanced Raman scattering and support vector machine

Surface-enhanced Raman scattering (SERS) technique combined with support vector machine (SVM) was implemented to identify and distinguish non-small-cell lung cancer (NSCLC) and small cell lung cancer (SCLC) cells from normal cells including blood cells and immortalized lung cells. Compared with normal cells, the intensity of nucleic acid characteristic peaks of NSCLC cells were slightly enhanced, while that of SCLC cells was significantly enhanced. SVM with linear, polynomial and radial based functions was used to create classification models for comparison and discrimination of the SERS spectra of different types of cells. The classification accuracy of 98.8% could be achieved for differentiation between NSCLC cells and normal cells. While in the classification of SCLC cells and normal cells, as well as SCLC cells and NSCLC cells, the accuracy reached 100%. These results suggested that SERS combined with SVM provide a reliable method for the identification of NSCLC cells and SCLC cells.

Dynamic Detection of Thiol Oxidation/Reduction Status During the Conversion of Cysteine/Cystine

• Dynamic detection of thiol oxidation/reduction status during the conversion of cysteine/cystine. • The thiol redox state is intuitively reflected by terahertz spectroscopy and Raman spectroscopy in varying degrees. The thiol redox state (TRS) plays a key role in evaluating essential biochemical processes, such as evaluating intracellular enzymatic activity. The TRS, characterized by the kinetic parameters of the thiol (–SH)/disulfide bond (–SS–) redox process, was measured by the Fourier-transform Raman spectroscopy (FT–Raman) and the terahertz time-domain spectroscopy (THz–TDS) in this study. A good correlation was observed between the disulfide concentration in samples and the intensities of the disulfide characteristic peaks in the FT–Raman and THz–TDS spectra. And the linear regression analysis correlation coefficients had values of 92.2% for FT–Raman-derived data and 95.4% for THz–TDS-derived data. The dynamic response of the cysteine/cystine experimental spectrum and characteristic peaks were analyzed by solid-state density functional theory. It can be found that both Raman and terahertz vibrational spectroscopy techniques can quantitatively analyze the ratio of cysteine/cystine. This provides a new method for the biological analysis of sulfur-containing amino acids and other related mixtures in basic science.

LIBS Monitoring and Analysis of Laser-Based Layered Controlled Paint Removal from Aircraft Skin

Reliability and controllability of selective removal of multiple paint layers from the surface of aircraft skin depend on effective online monitoring technology. An analysis was performed on the multi-pulse laser-induced breakdown spectroscopy (LIBS) on the surface of the aluminum alloy substrate, primer, and topcoat. Based on that, an exploration was conducted on the changes of the characteristic peaks corresponding to the characteristic elements that are contained in the topcoat, primer, and substrate with different layers of a laser action, in combination with analysis of microscopic morphology, composition, and depth of laser multi-pulse pits. The results show that the appearance and increase of the characteristic peak intensity of the Ca I at the wavelength of 422.7 nm can be regarded as the basis for the complete removal of the topcoat; the decrease or disappearance of the characteristic peak intensity can be regarded as the basis for the complete removal of the primer. Al I spectrum at the wavelength of 394.5 nm and 396.2 nm can be adopted to characterize the degree of damage to the aluminum alloy substrate. The feasibility and accuracy of the LIBS technology for the laser selective paint removal process and effect monitoring of aircraft skin were verified. Demonstrating that under the premise of not damaging the substrate, laser-based layered controlled paint removal (LLCPR) from aircraft skin can be achieved by monitoring the spectrum and composition change law of specified wavelength position corresponding tothe characteristic elements that are contained in the specific paint layer.

Rapid detection of orange II dyes in water with SERS imprinted sensor based on PDA-modified MOFs@Ag

In this paper, a novel SERS imprinted composite material was successfully synthesized with the aid of surface enhanced Raman scattering technology and molecular imprinting technology, which could be suitable for specific detection of organic dyes in the river. The UIO-66(NH2) was wrapped with a thin layer of polydopamine (PDA), after loading Ag nanoparticles on rough surface, Ag@UIO-66(NH2)/PDA was synthesized and applied as the SERS substrate. In order to promote the ability of selective detection property in the practical sample, the molecularly imprinted polymer (Ag@UIO-66(NH2)/PDA-MIPs) was proposed. When the concentrations range changed between 10−8 mol/L and 10−10 mol/L, the intensity of characteristic peak at 1596 cm−1 exhibited a linear relationship with OII concentrations increasing. The limit of detection was low than 10−10 mol/L, the correlation coefficient was 0.9985. The prepared SERS substrate could be available to the practical sample detection, which expanded SERS detection fields.

Two orders of magnitude extra SERS enhancement on silver nanoparticle-based substrate induced by laser irradiation in nitrogen ambient

Photo-reduction of silver oxide and light-induced Ag nanoparticle (NP) generations have been applied for Surface-enhanced Raman spectroscopy (SERS) substrate fabricated for years. In this paper, we demonstrate a general method to enhance the SERS activity of conventional Ag NPs-based SERS substrates by performing Raman scattering measurement in a nitrogen ambient after a period of laser irradiation (photoactivation). The Raman characteristic peak intensity of carbonaceous impurities adsorbed on the surfaces of Ag NPs display an additional enhancement of 93 times after photoactivation in nitrogen ambient. A 3-fold extra Raman gain enhancement is also observed in the nitrogen-protected SERS measurement of R6G molecules. The extra SERS enhancement is attributed to the sub-nanometer scale near-field coupling between the Ag NPs and the photo-generated Ag clusters in the surface oxide layer of Ag NPs. This model is verified through the finite-difference time-domain (FDTD) simulations.

Incorporation of amine functional group on surface of hydroxyapatite prepared fromstriped catfish (Pagasianodon hypophthalmus) bone

This study was conducted to incorporate amine functional groups on the surface of hydroxyapatite to enhance its potential application in biomedical materials. Hydroxyapatite particles (HA) were synthesized from striped catfish (Pagasianodon hypophthalmus) bone and surface modified by grafting with (3-aminopropyl)triethoxysilane (APTES). Important factors affected grafting efficiency such as concentration of APTES, water content, reaction temperature and reaction time were studied. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were used to confirm the grafting reaction on HA surfaces. Grafting efficiency was evaluated based on intensity of characteristic absorption peaks of APTES. The experimental results showed that amine functional groups were successfully introduced on HA surface at optimal condition of 0.2 M APTES, 0.75 wt.% water content, at 60°C and 12-hour reaction time.

In Situ Growth Large Area Silver Nanostructure on Metal Phenolic Network Coated NAAO Film and Its SERS Sensing Application for Monofluoroacetic Acid.

Rapid screening monofluoroacetic acid (FAcOH) is responsible for preventing chemical poisoning and food safety events. Whereas surface enhanced Raman scattering (SERS) spectra is an effective tool for detecting forbidden chemicals, it is difficult to directly detect FAcOH due to its small Raman scattering cross section as well as weak adsorption on SERS substrates. In this work, the metal phenolic supramolecular networks (MPNs, i.e., the tannic acid and Fe3+ complex) were fabricated on the commercial nanoanodic aluminum oxide film (NAAO) for assisting in situ chemical deposition highly uniform Ag nanostructure over large areas (the NAAO@AgNS). The low cost and simple fabrication process made the NAAO@AgNS a single-use consumable. For FAcOH detection, a specific derivative reaction between FAcOH and thiosalicylic acid (TSA) was introduced. By taking TSA as the Raman probe, its SERS signal attenuated constantly with the increasing amount of FAcOH. For improving quantitative accuracy, thiocyanate (SCN-) was introduced on the NAAO@AgNS as an internal standard; thus, the characteristic peak intensity ratios associated with TSA and SCN- (I1035/I2125) were fitted to the concentration of FAcOH. It was demonstrated that the SERS assay achieved good sensitivity and selection toward FAcOH with the limit of quantitation (LOD) as low as 50 nmol L-1. The NAAO@AgNS featured with highly sensitive, uniform, and consistent SERS performances could easily extend to wide SERS applications.

Quantitative detection on metabolites of Haematococcus pluvialis by terahertz spectroscopy

Stressed Haematococcus Pluvialis cells would accumulate astaxanthin with the changes of lipid, pigment, and starch, which recently has been widely studied. Real-time dynamic monitoring of these components will have important guiding significance for screening high-yield and high-quality strains in the industry. Terahertz spectroscopy is not only suitable for measuring large flux samples, but also widely used for quantitative analysis of multicomponent mixtures. To investigate the potential of using terahertz spectroscopy to monitor and quantify metabolites in the algae, terahertz spectrum of Haematococcus Pluvialis under nitrogen starvation were captured and examined against those standard reagents of β-carotene, astaxanthin, and starch. The correlation between intensities of the characteristic peaks and the metabolite contents which were quantified by chemical analysis was established, and the results showed the correlation coefficient were higher than 0.92, indicating a relatively accurate performance to predict the metabolites concentration. Furthermore, to identify meaningful spectra range for quantification, the partial least squares combined with intensities of the interval characteristic peaks were established, where it demonstrated an accurate model with high prediction correlation coefficients (greater than0.98), low root-mean-square error of prediction (RMSEP), and high residual predictive deviation. The results approve the feasibility of using terahertz spectroscopy for synchronous detection on metabolites concentration in the microalgae production process.

Study the interaction between juglone and calf thymus DNA by spectroscopic and molecular docking techniques

Juglone (Jug) is one of the main active substances of Cortex Juglandis Mandshuricae in a folk anti-cancer prescription. Previously, there were few studies on its interaction with DNA and mechanism of action. The present paper studied, the mechanism of action between Jug and calf thymus DNA (ctDNA) by fluorescence spectroscopy, together with ethidium bromide (EB) fluorescence probe, UV–vis absorption spectroscopy, salt effect and ctDNA melting point (Tm) experiment, resonance scattering spectroscopy and molecular docking under the simulated human physiological conditions. The experimental findings indicated that Jug quiescently quenched the fluorescence of EB-ctDNA system, characteristic absorption peak intensity of ctDNA presented a decolorization effect after the interaction of ctDNA and Jug, the interaction with ctDNA enhanced of Jug resonance scattering peak and generated new resonance scattering peak, the salt exerted less effect on the interaction between Jug and ctDNA molecules, and the interaction with Jug increased the Tm value of ctDNA by 5.0 °C The binding constant (KA) between Jug and ctDNA was 2.12 × 105 L/mol (310 K) and the number of binding sites (n) was about 1. The interaction between Jug and ctDNA was an entropically driven spontaneous and endothermic process. The results of molecular docking further showed that the naphthoquinone plane was embedded in the region between the two TA bases in the ctDNA groove, and the 5′-hydroxyl and 4-naphthoquinone groups extended to the outside of the ctDNA double helix.

Preparation and evaluation of starch-based extrusion-blown nanocomposite films incorporated with nano-ZnO and nano-SiO2

The effects of nano-ZnO and nano-SiO2 nanoparticles on the properties of starch-based films prepared by extrusion blowing were investigated in this study. New hydrogen bonds between hydroxypropyl starch (HS) and nanoparticles during the extrusion process were formed as shown by Fourier transform infrared spectroscopy (FTIR). The diffraction patterns of nanocomposite films reinforced with nano-ZnO were similar to those of nano-ZnO, except that the peak intensity decreased, whereas, the addition of SiO2 nanoparticles decreased the intensity of the main characteristic peaks, regardless of the HS and nano-ZnO reinforced films. The thermal stability, tensile strength, moisture barrier property, and surface hydrophobicity of nanocomposite films were improved with the incorporation of nano-ZnO and nano-SiO2, the finding that could be attributed to a strong interplay between nano-ZnO, nano-SiO2, and the starch matrix during the extrusion film blowing process. Similarly, the nano-ZnO/nano-SiO2 composite-reinforced films showed smooth, flat, and uniform appearances by scanning electron microscopy (SEM) and atomic force microscope (AFM) tests. In sum, Nano-ZnO and nano-SiO2 nanoparticles can be used as composite reinforcing agents for preparation of starch-based films through extrusion blowing.

Migration kinetic of silver from polylactic acid nanocomposite film into acidic food simulant after different high-pressure food processing.

The migration study of nano-Ag migration from polylactic acid (PLA) films was studied. Samples treated by high-pressure food processing (0, 100, 200, 300, and 400MPa pressure) were soaked in acetic acid solution and incubated at 20°C for 90 days. At the end of storage, nano-Ag particles (AgNPs) migration from the PLA/AgNPs composite film treated under 200MPa high pressure was the lowest. However, AgNPs migration was accelerated under 400MPa high pressure. High-pressure processing (200MPa) could cause denser structure and higher crystallinity degree in films than other treatments. Lower amount of AgNPs induced a decline in the intensity of specific characteristic peaks. The diffraction peak intensity of α-crystal for the film sample treated with 400MPa was the lowest on day 60. The crystallization index of the PLA matrix changed with different high-pressure processing. The result indicated that appropriate high-pressure food processing could effectively suppress AgNPs migration from PLA-based film while contacting with acidic acid food simulant. PRACTICAL APPLICATION: The release of nanoparticles from food packaging material is a very important matter when the migration is concerned with regulatory and toxicity issues. The study described the migration kinetic of AgNPs from PLA nanocomposite film into acidic food simulant after different high-pressure food processing. The results indicated that the PLA/AgNPs nanocomposite film was safe for acidic food after high-pressure treatment.

High-fidelity and high-resolution phase mapping of granites via confocal Raman imaging

In physical sciences such as chemistry and earth sciences, specifically for characterization of minerals in a rock, automated, objective mapping methods based on elemental analysis have replaced traditional optical petrography. However, mineral phase maps obtained from these newer approaches rely on conversion of elemental compositions to mineralogical compositions and thus cannot distinguish mineral polymorphs. Secondly, these techniques often require laborious sample preparations such as sectioning, polishing, and coating which are time-consuming. Here, we develop a new Raman imaging protocol that is capable of mapping unpolished samples with an auto-focusing Z-mapping feature that allows direct fingerprinting of different polymorphs. Specifically, we report a new methodology for generating high fidelity phase maps by exploiting characteristic peak intensity ratios which can be extended to any multi-phase, heterogenous system. Collectively, these enhancements allow us to rapidly map an unpolished granite specimen (~ 2 × 2 mm) with an exceptionally high accuracy (> 97%) and an extremely fine spatial resolution (< 0.3–2 µm).

SEBS effect on 60Co radiation resistance behavior of PP/HDPE matrix for medical device applications

Radiation resistant polypropylene (PP) has become more and more critical in the medical industry. Composites of PP were synthesized by melting process in the presence of high-density polyethylene (HDPE) and styrene–ethylene–butylene–styrene triblock copolymer (SEBS). Under 60Co γ-ray irradiation, all samples were characterized by mechanical properties, thermal analysis, contact angle (CA), FT-IR analysis, and SEM. Under a 20 kG y dose irradiation, mechanical properties results show that the impact strength rose from 3.28 kJ/m2 to 4.40 kJ/m2, and the tensile strength decreased by 3.52 MPa. At the same time, CA's results show that a much higher irradiation dose makes CA lower, but the higher content of SEBS, the higher CA. To confirm the presence of polar oxygen-containing groups, the FT-IR was used, and the results show that the characteristic peak intensity of carbonyl groups decreased gradually. SEM images indicate that the number of cracks and plastic particles reduced gradually, and the radiation resistance of samples enhanced by the aromatic ring structure of SEBS.

Detection of Soluble Mercury in Cinnabar Using a CV-Ag NPs SERS Probe.

In the current work a uniform morphological Ag nanoparticles (Ag NPs) were prepared with ascorbic acid as a reducing agent and citrate as a stabilizer. The surface of Ag NPs modified by crystal violet (CV) and potassium iodide (KI) was used as an aggregation agent to obtain CV modified Ag NPs (CV-Ag NPs) probes for detecting mercury ions. The mercury ions could be reduced to mercury molecules by citrate, and then deposited on the surface of Ag NPs, leading to the separation of CV molecules from the surface of Ag NPs. Therefore, the SERS signal intensity of CV decreased with the increase of the Hg2+ concentration and the concentration of Hg2+ was in the range of 1 × 10-11 to 1 × 10-5 M. Taking the change of the characteristic peak intensity of CV at 913 cm-1 as a reference, the SERS spectrum intensity of CV has a linear relationship with the Hg2+ concentration. The equation is y = -333.55x + 1343.05, where the linear correlation coefficient is R2 = 0.980, and the recovery rate is between 84.20 to 105.60%. Finally, the CV-Ag NPs probe was used to quickly detect soluble mercury in cinnabar. Compared with the conventional large-scale instrument detection method, this simple and fast method, can be applied for rapid detection of soluble mercury, and has a certain significance for concerning the research of mineral medicine processing mechanism.

Raman Spectroscopy Reveals Abnormal Changes in the Urine Composition of Prostate Cancer: An Application of an Intelligent Diagnostic Model with a Deep Learning Algorithm

Early diagnosis of prostate cancer (PCa) is always a great challenge in clinical practice, especially in distinguishing benign prostatic hyperplasia (BPH) from early cancer, due to the high similarity in pathology from the prostate‐specific antigen (PSA) test and radiological detection. The conventional diagnostic methods are often less efficient in specificity and accuracy, leading to quite a few unnecessary biopsies. This work establishes a noninvasive diagnostic method for PCa by investigating urine samples using Raman spectroscopy and convolutional neural network (CNN) algorithm. The results of urine Raman spectra show the intensities of characteristic peaks for lipids, nucleic acids, and some amino acids are distinguishable between PCa and BPH, suggesting an abnormal metabolism caused by PCa, which can be detected by Raman spectroscopy. These data are then used to train an intelligent diagnostic model with CNN algorithm. The cross‐validation results show the mean diagnostic accuracy, sensitivity, and specificity for PCa are 74.95%, 77.32%, and 72.46%, respectively. This noninvasive diagnostic method is a promising method for the early diagnosis of PCa, and the idea of using urine Raman spectroscopy with deep learning techniques for diagnosing PCa provides a reference for the application of artificial intelligence in the field of clinical medicine research.

Detection of benzo[a]pyrene with silver nanorod substrate in river water and soil based on surface-enhanced raman scattering

Benzo[a]pyrene (BaP) widely presents in soot, tar, cigarette smoke, and has a strong carcinogenic effect. It is stable in the environment and accumulates through the biological chain. Therefore, it is of vital importance to develop a simple and rapid method to detect Bap in real environment. In this work, based on surface enhanced Raman scattering (SERS) technology, a silver nanorod (AgNR) substrate was developed for detecting BaP in river water and soil. Vibration modes of BaP’s characteristic peaks were calculated by density functional theory (DFT). The characteristic peak of BaP is at 1234 cm−1. In the range of 10 ~ 100 ppb, the characteristic peak intensity of BaP shows good linear relationship with the concentration. The limit of detection (LOD) is down to 1 ppm in river water and 10 ppm in soil, respectively. These results demonstrate the applicability of the AgNR substrate for SERS detection of BaP which present an application prospect of AgNR substrate in environmental detection.