Raman study on single-walled carbon nanotubes with different laser excitation energies

The industrial use of carbon nanotubes is increasing day by day; therefore, it is very important to identify the nature of carbon nanotubes in a bundle. In this study, we have used the Raman spectroscopic analysis on vertically aligned single-walled carbon nanotubes (SWCNTs) grown by the chemical vapour deposition (CVD) technique. The grown sample is excited with two laser excitation wavelengths, 633 nm from He-Ne laser and 514·5 nm from Ar⁺ laser. Raman spectrum in the backscattering geometry provides the characteristic spectra of SWCNTs with its radial breathing mode (RBM), defect-induced disorder mode (D band), and high-energy modes (G and M bands). The Raman signal positions of the spectra in RBM, G and M bands confirm the grown sample to be of semiconducting type in nature.     

Phototransformation of C60 thin films by UV pulsed laser irradiation: comparative photoacoustic, AFM, and Raman studies

Fullerene C60 films deposited by sublimation were irradiated with Kr-F laser in a wide fluence interval from 15 to 40 mJ/cm2. In situ photoacoustic analysis was applied to study the phase transformation during the irradiation. The results obtained were discussed in conjunction with atomic force microscopy (AFM) and Raman spectroscopy data. It was found that for a irradiation fluence interval from 22 to 30 mJ/cm2, 80% of C60 undergoes photopolymerization (presumably through 2 + 2 cycloaddition). For a laser energy higher than 30 mJ/cm2, a new amorphous carbon phase forms, having a large content of diamond-like, tetra-amorphous carbon (ta-C).     

Human blood test based on surface‐enhanced Raman spectroscopy technology using different excitation light for nasopharyngeal cancer detection

Nasopharyngeal carcinoma (NPC), a kind of squamous cell carcinoma, occurs in the top and the side wall of nasopharyngeal, which harms human health and life. In this study, a novel blood test (SERS) was carried out for 30 NPC patients and 30 normal ones. Using multi‐variate statistical analysis for spectral data, the diagnostic sensitivities of 89.3% (50/56) and 85.7% (48/56) can be achieved for 633 and 785 nm exciting wavelength, respectively. Also corresponding specificities are 71.4% (41/56) and 78.6% (44/56), respectively. These results demonstrated that the two kinds of excitation wavelength all have the feasibility of obtaining high‐quality SERS spectra to differentiate cancer from normal samples. Furthermore, the performance of the SERS test with 785 nm wavelength excitation is nearly equal to the SERS experimental effect under 633 nm wavelength excitation for NPC detection.Inspec keywords: statistical analysis, blood, cancer, patient diagnosis, tumours, surface enhanced Raman scatteringOther keywords: human blood test, surface‐enhanced Raman spectroscopy technology, nasopharyngeal cancer detection, nasopharyngeal carcinoma, squamous cell carcinoma, human health, multivariate statistical analysis, spectral data, diagnostic sensitivities, excitation wavelength, high‐quality SERS spectra, normal samples, SERS test, SERS experimental effect, NPC detection, excitation light, NPC patients, wavelength excitation, wavelength 633.0 nm, wavelength 785.0 nm     

Step and repeat UV nanoimprint lithography on pre-spin coated resist film: a promising route for fabricating nanodevices

A step and repeat UV nanoimprint lithography process on pre-spin coated resist film is demonstrated for patterning a large area with features sizes down to sub-15 nm. The high fidelity between the template and imprinted structures is verified with a difference in their line edge roughness of less than 0.5 nm (3σ deviation value). The imprinted pattern's residual layer is well controlled to allow direct pattern transfer from the resist into functional materials with very high resolution. The process is suitable for fabricating numerous nanodevices.     

Anti-Stokes Raman spectrometry with 1064-nm excitation: an effective instrumental approach for field detection of explosives

Anti-Stokes Raman spectra of 28 explosive materials were obtained with 1064-nm excitation using fiber-optic sampling and a dispersive spectrograph equipped with a charge-coupled device (CCD) array detector. By using a silicon CCD detector, anti-Stokes features could clearly be observed for the majority of samples from -250 to -1650 cm(-1). Using the fiber-optic probe, spectra were routinely obtained from samples positioned up to twelve meters from the spectrograph within 240 s. The utility of an anti-Stokes correction routine is demonstrated, which routine allowed anti-Stokes spectra measured with 1064-nm excitation to be successfully searched and identified against libraries of Stokes spectra obtained using a Fourier transform (FT) Raman system equipped with a 1064-nm Nd:YAG laser.     

Growth,microhardness, dielectric and photoconductivity studies on NPNaLi: A promising crystal for NLO applications

Single crystals of nonlinear optical sodium substituted lithium p-nitrophenolate trihydrate (NPNaLi·3H₂O) have been grown successfully by slow solvent evaporation technique. The grown crystals are subjected to powder X-ray diffraction, microhardness, dielectric and photoconductivity studies. NLO activity of the crystal is found to be increased in the presence of sodium ions. Microhardness on (1 1 0) and (1 0 1) planes reveal the anisotropic behaviour in Vicker's hardness number. Dielectric constant is found to be less and independent at higher frequencies. Electrical conductivity and photoconductivity are found to be increasing in the presence of sodium in the lattice of NPLi. The results of SEM analysis also have been revealed.     

Proteolytic 18O labeling for comparative proteomics: model studies with two serotypes of adenovirus

A new method for proteolytic stable isotope labeling is introduced to provide quantitative and concurrent comparisons between individual proteins from two entire proteome pools or their subfractions. Two 18O atoms are incorporated universally into the carboxyl termini of all tryptic peptides during the proteolytic cleavage of all proteins in the first pool. Proteins in the second pool are cleaved analogously with the carboxyl termini of the resulting peptides containing two 16O atoms (i.e., no labeling). The two peptide mixtures are pooled for fractionation and separation, and the masses and isotope ratios of each peptide pair (differing by 4 Da) are measured by high-resolution mass spectrometry. Short sequences and/or accurate mass measurements combined with proteomics software tools allow the peptides to be related to the precursor proteins from which they are derived. Relative signal intensities of paired peptides quantify the expression levels of their precursor proteins from proteome pools to be compared, using an equation described in the paper. Observation of individual (unpaired) peptides is mainly interpreted as differential modification or sequence variation for the protein from the respective proteome pool. The method is evaluated here in a comparison of virion proteins for two serotypes (Ad5 and Ad2) of adenovirus, taking advantage of information already available about protein sequences and concentrations. In general, proteolytic 18O labeling enables a shotgun approach for proteomic studies with quantitation capability and is proposed as a useful tool for comparative proteomic studies of very complex protein mixtures.     

Text mining as a tool for real-time technology assessment: Application to the cross-national comparative study on artificial organ technology

This study proposed a methodology that integrate sociotechnical systems (STS) and media big data analysis using text mining for the new, real-time technology assessment (TA). The essential steps of this method are composed of data collection using a cultural map, analysis with trends and patents, and synthesis using media big data. By applying this methodology to artificial organs, first, we have shown that STS can be apply to biosocial technical systems beyond the sustainability transition. The result reveals that a media discourse structures, in which eight countries began to form socio-technical regimes around technologies with their respective strengths, in an objective way. Each technology corresponded to the vested interests in each country's socio-technical regimes. These discourse structures helped us to identify substitution, two types of transformation, and reconfiguration as transition pathways. More importantly, our analysis results have also shown that the methodology helps to overcome the anticipation dilemma, saving the time and resources required for TA. Our integrated methodology has achieved similar results by using 23% of the budget, 25% of the time, and 14% of the work hours used for official TA. Lastly, the “objectivity” and “agenda setting” of this methodology can provide a breakthrough in overcoming the control dilemma.     

A comparative study on electrochemical performances of the electrodes with different nanocarbon conductive additives for lithium ion batteries

Three nanocarbon materials (0 D acetylene black (AB), 1 D carbon nanotubes (CNTs) and 2 D reduced graphene oxide (RGO)) were used as conductive additives (CAs) in the mesocarbon microbead anodes for lithium ion batteries. The electrochemical performances of the electrodes were investigated. The results show that the CAs have a significant impact on the electrode performance because they can influence the electron conduction and lithium ion transportation within the electrode. The electrode with RGO achieves a maximum capacity of 387 mAh g⁻¹ after 50 cycles at a current density of 50 mA g⁻¹, much higher than those of the electrodes with AB (334 mAh g⁻¹) and CNTs (319 mAh g⁻¹). The improvement should be mainly ascribed to the “plane-to-point” conducting network formed in the electrode with 2 D RGO which can favor the electron conduction and enhance the lithium ion transportation.     

Frontal affinity chromatography combined on-line with mass spectrometry: a tool for the binding study of different epidermal growth factor receptor inhibitors

Frontal affinity chromatography (FAC) is a simple but powerful method to analyze molecular interactions between an analyte and an immobilized ligand by calculating the extent of retardation of the elution front. By combination of FAC with a PE-Mariner electrospray ionization mass spectrometry, a very efficient and straightforward procedure was developed herein for analyzing the binding properties of different inhibitors of the epidermal growth factor receptor (EGFR). In this study, a polyclonal antibody prepared with a known anti-EGFR inhibitor coupled with bovine serum albumin was adopted as the stationary phase in the FAC system. Using the antibody to mimic the receptor, other different anti-EGFR inhibitors as well as the small-molecule half-antigen itself were recognized directly from the crude extract of herb, which afforded us a novel promising approach for the efficient screening of lead compounds or drug candidates from natural resources.     

Crystal growth,vibrational assignments,Z-scan studies and quantum chemical investigation on 2-methylimidazolium hydrogen d-tartrate (2MIMDT) single crystal: a promising candidate for NLO applications

Journal of Materials Science: Materials in Electronics - Good quality single crystal, 2-Methylimidazolium d-tartrate (2MIMDT) (C8N2O6H12) was grown by slow evaporation solution growth method. The...     

Integration of knowledge-based metabolic predictions with liquid chromatography data-dependent tandem mass spectrometry for drug metabolism studies: application to studies on the biotransformation of indinavir

Despite recent advances in the application of data-dependent liquid chromatography/tandem mass spectrometry (LC/MS/MS) to the identification of drug metabolites in complex biological matrixes, a prior knowledge of the likely routes of biotransformation of the therapeutic agent of interest greatly facilitates the detection and structural characterization of its metabolites. Thus, prediction of the [M + H]+ m/z values of expected metabolites allows for the construction of user-defined MS(n) protocols that frequently reveal the presence of minor drug metabolites, even in the presence of a vast excess of coeluting endogenous constituents. However, this approach suffers from inherent user bias, as a result of which additional "survey scans" (e.g., precursor ion and constant neutral loss scans) are required to ensure detection of as many drug-related components in the sample as possible. In the present study, a novel approach to this problem has been evaluated, in which knowledge-based predictions of metabolic pathways are first derived from a commercial database, the output from which is used to formulate a list-dependent LC/MS(n) data acquisition protocol. Using indinavir as a model drug, a substructure similarity search on the MDL metabolism database with a similarity index of 60% yielded 188 "hits", pointing to the possible operation of two hydrolytic, two N-dealkylation, three N-glucuronidation, one N-methylation, and several aromatic and aliphatic oxidation pathways. Integration of this information with data-dependent LC/MS(n) analysis using an ion trap mass spectrometer led to the identification of 18 metabolites of indinavir following incubation of the drug with human hepatic postmitochondrial preparations. This result was accomplished with only a single LC/MS(n) run, representing significant savings in instrument use and operator time, and afforded an accurate view of the complex in vitro metabolic profile of this drug.     

Effect of porous NiTi alloy on bone formation: A comparative investigation with bulk NiTi alloy for 15 weeks in vivo

The purpose of this study is to investigate the effect of porous NiTi alloy on bone formation with a bulk NiTi alloy as a contrast. The porous NiTi alloy prepared by element powder sintering under Ar protection has a porosity of 45% and a mean pore size of 130 μm, and the pores are highly interconnected. The porous and bulk NiTi alloys were bilaterally implanted into the femurs of rabbits for 15 weeks. The bone-implant interface and bone ingrowth were evaluated by undecalcified histological examination under light and fluorescent microscope as well as environmental scanning electron microscope (ESEM). The results show: osteoblasts are very active with fast proliferation and no adverse tissue reaction occurs for the porous NiTi alloy after 15 weeks implantation; porous NiTi alloy has better osteoconductivity and osteointegration than the bulk one; the osteoblasts can ingrow the pores of porous NiTi implant, and direct bone-implant interface can be observed by fluorescent light microscope.     

Photoelectrochemical studies on colloidal copper (I) oxide/modified with some organic semiconductors: Incentive for use of nanoparticle systems

Colloidal Cu₂O solutions were used to explore photonic activities at the semiconductor/electrolyte interface. Fluorescence spectroscopic studies were performed on Cu₂O colloidal particles modified with some conjugated organic monomers such as 2-amino-phenyl pyrrole (2-APPy), tri-phenyl amine (TPA), or 2-thionyl pyrrole (2-Th-Py) to investigate the quantum absorbance efficiency at this inorganic/organic interface (IOI). Our study shows that colloidal p-type Cu₂O possesses a bandgap with direct transition of ≈ 2·2 eV and indirect transition of 1·85 eV. The recorded rates of charge injection into colloidal Cu₂O, k _ct, were 2·31 × 10⁹ s⁻¹, 5·05 × 10⁸ s⁻¹, and 7·22 × 10⁸ s⁻¹ for 2-APPy, TPA and 2-Th-Py, respectively. The studied systems show more stability in colloidal form than in thin solid form. Results were interpreted using the optical and electrical parameters of the organic monomer such as ionization potential (IP), electron affinity (EA) and energy bandgap (Eg), and the barrier height at the IOI interface. Stability of the colloidal system is attributed to the physical dimensions of the photoactive system. The nano-colloidal particle offers a condition where its size is less than √Dt.     

Resistivity studies on different variants of κ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for Disorder and/or defect-induced inelastic scattering contributions

Comparative resistivity measurements have been performed on differently prepared κ-(ET)₂Cu[N(CN)₂]Br single crystals. While the T_c values and their shifts under hydrostatic pressure are found to be sample independent, the resistivity profiles, especially around the resistivity hump at 90 K and the low-temperature ρ ∝ T² behavior, show striking sample-to-sample variations. In the absence of significant differences in the crystals’ structural parameters and chemical compositions, as proved by high-resolution X-ray and electron-probe-microanalysis studies, these results indicate that real structure phenomena, i.e. disorder and/or defects, strongly affect the inelastic scattering in these molecular conductors.