Relative Peak Intensities Research Articles

Simulating pH‐dependent surface‐enhanced Raman spectra by density functional theory calculations

AbstractThe pH‐dependent surface‐enhanced Raman spectra of two typical surface sensor molecules p‐mercaptobenzoic acid (PMBA) and p‐mercaptopyridine (PMPY) were simulated by density functional theory calculations. First, the acid dissociation constants and individual surface Raman spectra of PMBA and PMPY were computed and compared with experimental results. It was found that acid dissociation constants calculated by the hybrid implicit‐explicit model and surface‐enhanced Raman scattering (SERS) spectra simulated by the explicit model most closely coincide with experimental results. Then, the pH‐dependent SERS spectra of PMBA and PMPY were obtained by overlaying the SERS of individual acid species and base species multiplied by their molar fractions, which were calculated from the acid dissociation constants. During the deprotonation process of PMBA, the Raman intensity from COOH stretching decreases and the Raman intensity from COO− stretching increases. During the protonation process of PMPY, the ν8a mode undergoes a significant blueshift and the relative Raman intensity of ν7a mode decreases. At last, pH calibration curves of PMBA and PMPY were obtained according to the simulated pH‐dependent Raman spectra, in which the logarithmic value of relative Raman intensity of characteristic peaks varies almost linearly with solution pH.

Optical and Molecular Signatures of Dissolved Organic Matter Reflect Anthropogenic Influence in a Coastal River, Northeast China.

Sources and molecular composition of dissolved organic matter (DOM) in coastal rivers have been tightly linked with its reactivity and fate, thus influencing element and nutrient cycling. The DOM in coastal rivers is usually sourced from both terrestrial and marine inputs, with further complication by anthropogenic activities, which is less understood in coastal rivers located near populated industrial regions. In this study, DOM in a typical anthropogenically influenced coastal river, Daliao River, was analyzed for optical analyses and for molecular composition via Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to give a better scope of composition and sources of DOM. The DOM was enriched in autochthonous and anthropogenic inputs at upstream sites according to high chlorophyll a concentrations, strong protein-like fluorescence, and nonoxygen heteroatomic CHOS formulae (19-24% by relative peak intensity) detected by FT-ICR MS analysis. A series of surfactant-like formulae, indicative of wastewater inputs, were identified and showed a decreasing trend from upstream to the river mouth. Compared with large world rivers, the DOM of Daliao River is characterized by higher abundances of heteroatomic (excluding O) formulae and molecular lability, which is likely caused by strong autochthonous and anthropogenic inputs. In general, we demonstrate that in addition to optical properties, the molecular composition can assess the specific anthropogenic imprints and molecular lability of DOM, which is essential for constraining sources and identifying processes during the transit of DOM from the river to estuary with increasing urbanization and industrialization.

Effects of Heat Input on Weld-Bead Geometry, Surface Chemical Composition, Corrosion Behavior and Thermal Properties of Fiber Laser-Welded Nitinol Shape Memory Alloy

Bead-on-plate laser welding was carried out on 1-mm-thick Nitinol sheets at different heat input values. The variations in weld-bead geometry and variations in microstructures across the bead were studied. The effects of heat input on surface layer composition of the welded samples, corrosion properties and phase transformation temperature were examined. From x-ray photoelectron spectroscopy (XPS), it was clear that relative intensity of elemental Ni peak was higher in parent material and the oxidation state of Ti was Ti4+. It was further observed from Auger electron spectroscopy (AES) that the Ti to Ni ratio on the top surface of the welded samples was more than 1, and as a result of this the stability of TiO2 layer was enhanced, which eventually helped to improve the corrosion property of the welded samples. The polarization resistance of the welded samples was increased by more than ten times compared to that of the un-welded samples. From differential scanning calorimetry (DSC), it became evident that phase transformation temperatures got changed due to welding.

KMMRAE structure and Sawada lines of Co, Ni, Cu, Zn and Ga

Kβ spectrum of Co, Ni, Cu, Zn and Ga generated by photoexcitation is studied using a WDXRF spectrometer. KMM RAE structure is de-convoluted into six components. The energy shift of the peaks of these components relative to the diagram line is determined and compared with various theoretical estimates available. The integrated relative intensity of KMM structure is measured. The energy and relative intensity of Sawada lines and Kβ5 peaks are also measured.

Photochemical Synthesis and Catalytic Applications of Gold Nanoplates Fabricated Using Quercetin Diphosphate Macromolecules.

The demand for safer design and synthesis of gold nanoparticles (AuNPs) is on the increase with the ultimate goal of producing clean nanomaterials for biological applications. We hereby present a rapid, greener, and photochemical synthesis of gold nanoplates with sizes ranging from 10 to 200 nm using water-soluble quercetin diphosphate (QDP) macromolecules. The synthesis was achieved in water without the use of surfactants, reducing agents, or polymers. The edge length of the triangular nanoplates ranged from 50 to 1200 nm. Furthermore, the reduction of methylene blue was used to investigate the catalytic activity of AuNPs. The catalytic activity of triangular AuNPs was three times higher than that of the spherical AuNPs based on kinetic rate constants (k). The rate constants were 3.44 × 10–2 and 1.11 × 10–2 s–1 for triangular and spherical AuNPs, respectively. The X-ray diffraction data of gold nanoplates synthesized by this method exhibited that the nanocrystals were mainly dominated by (111) facets which are in agreement to the nanoplates synthesized by using thermal and chemical approaches. The calculated relative diffraction peak intensity of (200), (220), and (311) in comparison with (111) was found to be 0.35, 0.17, and 0.15, respectively, which were lower than the corresponding standard values (JCPDS 04-0784). For example, (200)/(111) = 0.35 compared to 0.52 obtained from the standard (JCPDS 04-0784), indicating that the gold nanoplates are dominated by (111) facets. The calculated lattice from selected area electron diffraction data of the as-synthesized and after 1 year nanoplates was 4.060 and 4.088 Å, respectively. Our calculations were found to be in agreement with 4.078 Å for face-centered cubic gold (JCPDS 04-0784) and literature values of 4.07 Å. The computed QDP–Au complex demonstrated that the reduction process took place in the B ring of QDP. This approach contributes immensely to promoting the ideals of sustainable nanotechnology by eradicating the use of hazardous and toxic organic solvents.

Effects of continuous cropping with straw return on particulate organic carbon and Fourier transform infrared spectroscopy in cotton field

A long-term field experiment was conducted to investigate the effects of continuous cotton production years (0 as control, 5, 10, 15 and 20 years) and straw return on soil organic carbon (SOC) structure and stability by using Fourier transform infrared spectroscopy (FTIR) in Manas River valley of Xinjiang. The results showed that the relative peak intensity of polysaccharide and aromatics decreased with increasing continuous cropping years, whereas the aliphatic and alcoholic phenols relative peak intensity and the CH/C=C increased. The content of soil particulate organic carbon (POC) increased significantly in the 5-yr of cotton production farmland and then decreased with the increases of continuous cropping years. POC content was 5.11 times higher in 5-yr than that of the control. The content of mineral-bound organic carbon (MOC) was the highest in 10-yr farmland, being 1.84 times higher than that of the control. The highest value of the ratio of POC and MOC content (ω(POC)/ω(MOC)) was observed in 5-yr farmland. Together, long-term continuous cotton production with straw return led to SOC structure aliphatic and soil mineral binding increased the protection of organic matter, thus increasing the stability of soil organic matter.

Effect of Hydrogen Bonding on the Surface Tension Properties of Binary Mixture (Acetone-Water) by Raman Spectroscopy

The structure and properties of water and aqueous solutions have always been the focus of attention. The surface tension of acetone aqueous solutions were measured by using Raman spectra in different molecule environments, and the changes of surface tension were analyzed with hydrogen bonding in the mixtures. In this case, OH stretching bands were fitted into three Gaussian components and then assigned to different hydrogen-bonded structures. Furthermore, it can be concluded that the changes of microstructure on the binary mixture solutions exhibited regularly with the additive acetone, indicating that there showed the correlation between surface tension and relative peak intensity. The results show that the strengthening of hydrogen bonding between acetone and water will gradually weaken the surface tension of the solutions. It was confirmed that there showed the relationship between the microstructure and macroscopic properties of the aqueous solutions by the basis experiment data using a spectroscopy method.

Effects of crystal quality, grain-size and oxygen vacancy of nanocrystalline CeO2 films under 1.5 MeV Au ion irradiation

Nanocrystalline CeO2 films with thickness of approximate 250 nm were grown on Si substrates using a sol-gel process with spin-coating method. The films were then irradiated with 1.5 MeV Au ions to the doses of 2.5, 15.0 and 35.0 dpa at room temperature. Electron microscope results show that the surface of the as-grown CeO2 film is very smooth, and no any cracks are detected. The as-grown CeO2 film is cubic fluorite structure with an average grain-size of 6.4 nm. The nanocrystalline CeO2 films remain cubic structure under all irradiation conditions. The crystallinity and average grain-size of the CeO2 film decrease with the increase of irradiation dose, which is due to the competing effects of electronic and nuclear energy loss. As the irradiation dose is up to 35.0 dpa, the crystal quality is obviously deteriorated as well as the surface microstructure. Raman spectra also confine that the grain-size of the nanocrystalline CeO2 films decreases with the irradiation dose increase. X-ray photoelectron spectroscopy (XPS) results reveal that parts of Ce4+ in the nanocrystalline CeO2 films change to Ce3+, and oxygen vacancy concentration also increases after irradiation. All these samples exhibit two emission bands in the photoluminescence (PL) spectra, and the relative emission intensity of the defect peak centered at 500 nm is enhanced by ion irradiation, which also indicates that irradiation introduces oxygen vacancies into the nanocrystalline CeO2 films. This work provides a useful way to control the grain-size and oxygen vacancy of the nanocrystalline CeO2 films through ion implantation technique.

Optical Transparency and Local Electronic Structure of Yb-Doped Y2O3 Ceramics with Tetravalent Additives

The results of optical transmission and X-ray core-level spectra measurements of Yb:Y2O3 ceramics with different tetravalent sintering additives (ZrO2, CeO2 and HfO2) fabricated from nanopowders (produced by the laser ablation method) and then annealed at 1400 ℃ in air for 2 h are presented. It is found that the transmission values for ZrO2- and HfO2-doped ceramics at the lasing wavelengths are higher than those of CeO2-doped samples. The X-ray photoelectron spectra (XPS) O 1s spectra show that the relative intensity of oxygen defect peak detected for 3Yb:Y2O3 + 5CeO2 ceramics decreases substantially and consistently compared to that of 5Yb:Y2O3 + 5HfO2 and 3Yb:Y2O3 + 5ZrO2 samples. This can be attributed to a more complete filling of oxygen vacancies due to annealing-induced oxygen diffusion into the highly defective sintered ceramics. The measurements of XPS Ce 3d spectra showed that the insufficiently complete filling of the oxygen vacancies in the 3Yb:Y2O3 + 5CeO2 compound is due to the appreciable presence of trivalent cerium ions.

Preparation, electronic structure and piezooptical properties of solid solutions Tl3PbBr5–I

Abstact Phase diagram of the Tl3PbBr5–Tl3PbI5 section of the reciprocal system 2TlI + PbBr2⇔2TlBr + PbI2 was investigated by differential thermal and X-ray phase analysis methods on 18 alloys. The section is quasi-binary, of eutectic type, with the invariant point coordinates 76 mol% Tl3PbI5 and 355 °C. The addition of Tl3PbI5 results in stabilization of the high-temperature (HT) modification of Tl3PbBr5 forming a substitution solid solution, which at room temperature occupies the concentration range of ∼9–71 mol% Tl3PbI5. The solid solution range of low-temperature (LT) Tl3PbBr5 is minor (0–∼6 mol% Tl3PbI5), and that of Tl3PbI5 is in the range of ∼71–100 mol% Tl3PbI5. Tl3PbBr2.5I2.5 crystals were grown by Bridgman-Stockbarger method; they belong to wide-gap semiconductors with Eg decreasing from 2.45 eV at 100 K to 2.36 eV at 300 K. Based on X-ray photoelectron (XP) core-level spectra, one can conclude that the Tl3PbBr2.5I2.5 crystal reveals the XP fine-structure peculiarities well ascribed to thallium, lead, bromine and iodine, constituent atoms of the quaternary halide under consideration. Treatment of the Tl3PbBr2.5I2.5 crystal with 3 keV Ar+ ions reveals that the Pb–I bonds are somewhat weaker in this compound, as compared to the Pb–Br, Tl–Br and Tl–I bonds. Comparison with the similar XP measurements of the related ternary bromide and iodide (Tl3PbBr5 and Tl3PbI5) indicates that the positive effective charge of lead atoms gradually decreases when going from Tl3PbBr5 to Tl3PbBr2.5I2.5 and, further, to Tl3PbI5, while the charge state of thallium atoms does not change in the above sequence of compounds. In the sequence Tl3PbBr5 → Tl3PbBr2.5I2.5 → Tl3PbI5 the relative peak intensity of the XP valence-band spectrum monotonously decreases. The laser stimulated piezooptics at 1150 nm excited by 1540 nm Er:glass nanosecond laser and its second harmonic generation are reported.

Effect of MnO on the microstructure and electrical properties of SnO2–Zn2SnO4 ceramic composites

This work presents the microstructure and electrical properties of MnO-doped SnO2–Zn2SnO4 ceramic composites prepared through conventional ceramic processing. Scanning electron microscopy images reveal that all samples have a compact structure. With increasing MnO content, the grains grow larger and the grain boundaries become unsharp. Energy dispersive spectroscopy results for the sample doped with 0.1 mol% MnO indicate that Mn distributes randomly on the grain surfaces. X-ray diffraction patterns exhibit that all the samples are composed of SnO2 and Zn2SnO4, and the relative intensity of the diffraction peak for Zn2SnO4 increases with increasing MnO content. The relations between the electric field and current density show that all the samples have varistor properties. For the samples doped with 0.2 and 0.3 mol% MnO, the breakdown electric field is so large that it exceeds the measuring range of the instrument, whereas the relative permittivity is as low as about 30 at 100 Hz. In the electric modulus spectra, two sets of relaxation peaks were observed and the corresponding activation energies are enhanced greatly by doping MnO. The effect of MnO on the microstructure and electrical properties indicates that the space charges trapped by oxygen vacancies are the origin of the great permittivity and varistor properties for SnO2–Zn2SnO4 ceramic composites.

Analysis of platelets in hypertensive and normotensive individuals using Raman and Fourier transform infrared‐attenuated total reflectance spectroscopies

AbstractPlatelets of both healthy and hypertensive subjects were analyzed by Raman and Fourier transform infrared by attenuated total reflectance (FTIR‐ATR) spectroscopies. We compared the average relative intensities of the main Raman peaks, the areas of convoluted bands in the amide I region, and the second derivative of the FTIR‐ATR spectra. Key differences were found in the bands reflecting lipid content and protein structure. The Raman spectra exhibited statistically significant changes in the intensity of bands associated with CC stretching vibrations in the carbon chains of lipids (960 cm−1) and the amide I band (centered at 1,658 cm−1). The amide I deconvolution showed changes in the area percentages of the bands corresponding to different protein secondary structures, suggesting biochemical and protein conformational differences between healthy versus arterial hypertension platelets, which might be related to the platelet activation stage. An analysis by using the second derivative of the FTIR‐ATR spectra, followed by deconvolution of amide regions support this observation, revealing differences in the amide II and amide I bands. Moreover, modifications observed in the phosphate‐associated bands are possibly related to the phospholipids' behavior and the phosphorylation of proteins. Our results suggest interesting differences between the spectra of healthy versus hypertensive platelets, which may be mainly associated with biochemical changes at the cellular membrane level.

Uncertainty in linewidth quantification of overlapping Raman bands

Spectral linewidths are used to assess a variety of physical properties, even as spectral overlap makes quantitative extraction difficult owing to uncertainty. Uncertainty, in turn, can be minimized with the choice of appropriate experimental conditions used in spectral collection. In response, we assess the experimental factors dictating uncertainty in the quantification of linewidth from a Raman experiment highlighting the comparative influence of (1) spectral resolution, (2) signal to noise, and (3) relative peak intensity (RPI) of the overlapping peaks. Practically, Raman spectra of SiGe thin films were obtained experimentally and simulated virtually under a variety of conditions. RPI is found to be the most impactful parameter in specifying linewidth followed by the spectral resolution and signal to noise. While developed for Raman experiments, the results are generally applicable to spectroscopic linewidth studies illuminating the experimental trade-offs inherent in quantification.

Performance and Environmental Impact of Rice Straw Fiber Mulching Films Manufactured with a Warming Agent

Abstract. This research evaluates the effects of adding various warming agents to rice straw fiber (RSF) films as sustainable alternatives to polyethylene-based films. The results for the mechanical properties of the RSF films with various warming agents show that the mean values of dry tensile strength and bursting strength of the films significantly differed according to the warming agent; in contrast, the mean wet tensile strengths and tearing strengths were not significantly different. The dry tensile strengths of films containing titanium dioxide were 9.7% and 26.8% higher than those of the films containing talc and kaolin, respectively. Additionally, the bursting strengths of the films containing titanium dioxide, calcium carbonate, and talc were 10.5%, 4.4%, and 15.8% higher, respectively, than those of the films containing kaolin. Thus, titanium dioxide was considered the best of the four warming agents for implementation in these films. The absorption peaks of the films with and without titanium dioxide were similar, with some differences in the peak position and relative intensities by Fourier transform infrared spectroscopy. Soil covering tests were conducted with films containing titanium dioxide (TDF), films with no added titanium dioxide, and a blank group. The degradation rate of the TDF reached grade 3 during the bolting stage of bok choy. At soil depths of 0, 5, and 10 cm, the total accumulated temperature of the TDF group was 11.53%, 7.78%, and 5.38% higher, respectively, than that of the blank group. Both TDF degradation and increased soil temperature improved the crop growth and soil microclimate. These results can serve as a reference to further improve the popularization and application of RSF film. Keywords: Degradable films, Mechanical properties, Rice straw, Soil temperature, Titanium dioxide.

Powder XRD, PSD and DSC Analysis of the Consciousness Energy Healing Treated Zinc Chloride

Zinc chloride is commonly used as a source of zinc for the treatment of many diseases and overall maintenance of good health. The impacts of the Trivedi Effect® on the physicochemical, thermal, and behavioral properties of zinc chloride were evaluated using sophisticated analytical techniques. Zinc chloride was divided into control and treated parts. Only, the treated part received the Trivedi Effect®-Consciousness Energy Healing Treatment remotely by a renowned Biofield Energy Healer, Dahryn Trivedi. The powder XRD relative peak intensities and crystallite sizes of the treated zinc chloride were significantly altered ranging from -58.73 to 141.43 and -74.03 to 228.56%, respectively compared with the control sample. The average crystallite size of the treated zinc chloride was significantly increased by 4.34% compared with the control sample. The particle sizes of the treated zinc chloride sample were significantly altered by 11.04% (d10), -11.85% (d50), -20.35% (d90), and -21.88% {D (4, 3)} compared with the control sample. Thus, the surface area of the treated zinc chloride (10400 m2/g) was significantly increased by 112.24% compared with the control sample (4900 m2/g). The latent heat of fusion and decomposition of the treated sample were significantly increased by 96.18% and 134.66%, respectively compared with the control sample. The current study predicted that the Trivedi Effect®-Consciousness Energy Healing Treatment might produce a new polymorphic form of zinc chloride with larger crystallite size, smaller particle size, and increased surface area, which would improve the solubility, absorption, bioavailability, and thermal stability compared with the control sample. Therefore, the Consciousness Energy Healing Treated zinc chloride would be very useful to design more efficacious nutraceutical or pharmaceutical formulations for the treatment of immunological disorders, inflammatory diseases, aging, stress, cancer, parakeratosis, dysosmia, hypogonadism, Wilson’s disease, anorexia, etc.

Subunit mass analysis for monitoring multiple attributes of monoclonal antibodies

Multi-Attribute Methods (MAMs) are appealing due to their ability to provide data on multiple molecular attributes from a single assay. If fully realized, such tests could reduce the number of assays required to support a product control strategy while providing equivalent or greater product understanding relative to the conventional approach. In doing so, MAMs have the potential to decrease development and manufacturing costs by reducing the number of tests in a release panel. In this work, we report a MAM which is based on subunit mass analysis. The MAM assay is shown to be suitable for use as a combined method for identity testing, glycan profiling, and protein ratio determination for co-formulated monoclonal antibody (mAb) drugs. This is achieved by taking advantage of the high mass accuracy and relative quantification capabilities of intact mass analysis using quadrupole time-of-flight mass spectrometry (Q-TOF MS). Protein identification is achieved by comparing the measured masses of light chain (LC) and heavy chain (HC) mAbs against their theoretical values. Specificity is based on instrument mass accuracy. Glycan profiling and relative protein ratios are determined by the relative peak intensities of the protein HC glycoforms and LC glycoforms, respectively. Results for these relative quantifications agree well with those obtained by the conventional hydrophilic interaction liquid chromatography (HILIC) and reversed-phase LC methods. The suitability of this MAM for use in a quality control setting is demonstrated through assessment specificity for mAb identity, and accuracy, precision, linearity and robustness for glycan profiling and ratio determination. Results from this study indicate that a MAM with subunit mass analysis has the potential to replace three conventional methods widely used for mAb release testing including identification assay, glycosylation profiling, and ratio determination for co-formulated mAbs.

Probing Adsorption Configurations of Small Molecules on Surfaces by Single-Molecule Tip-Enhanced Raman Spectroscopy.

Determining the adsorption configurations of organic molecules on surfaces, especially for relatively small molecules, is a key issue for understanding the microscopic physical and chemical processes in surface science. In this work, we have applied low-temperature ultrahigh-vacuum tip-enhanced Raman scattering (TERS) technique to distinguish the configurations of small 4,4'-bipyridine (44BPY) molecules adsorbed on the Ag(111) surface. The observed Raman spectra exhibit notable differences in the spectral features which can be assigned to three different molecular orientations, each featuring a specific fingerprint pattern based on the TERS selection rule that determines the distribution of the relative intensities of different vibrational peaks. Furthermore, such a small molecule can in turn act as a local probe to provide information on the local electric field distribution at the tip apex. Our work showcases the capability of TERS technique for obtaining information on adsorption configurations of small molecules on surfaces down to the single-molecule level, which is of fundamental importance for many applications in the fields of molecular science and surface chemistry.

Electromagnetic Noise Suppression Composite Sheets Made of Hexagonal Ferrite Particles

In the early stage 5th generation mobile phone system, it is expected to use high frequencies up to the SHF band (3 to 30 GHz) [1]. Therefore new noise countermeasure material is necessary in this band [2]. In this paper, we studied M-type, Y-type and Z-type hexagonal ferrite fine particles in composite form with epoxy resin, to find candidate for this application through SEM observation, XRD, DC hysteresis loop, high frequency complex permeability, and conduction noise suppression effect on micro stripline(MSL).Preparation and properties of fine particles– While Sr and Ba hexagonal ferrite materials are known as permanent magnet materials, they are also useful as high frequency materials whose ferromagnetic resonance (FMR) frequency exceeds 20 GHz, which corresponds to the center frequency of noise suppression exceeds 20 GHz. Firstly we followed a known direction to reduce magneto-crystalline anisotropy by a 1 – 2 at% substitution of Fe3+ions by a combination of metal ions such as Co2+and Ti4+. Table Ishows list of test perticles; Z-type Ba 3 Zn 2−X Co x Fe 24 O 41 (x=1.25), Y-type Ba 2 Zn 2 Fe 12 O 22 , and M-type SrCo x Ti x Fe 2−x O 19 (x=1.4) [3]. The fired polycrystalline material was pulverized to obtain fine particles. The XRD pattern showed that the crystal structure is mainly composed of hexagonal crystals since the relative intensity and diffraction angle of the main diffraction peak agree with the values of the JCPDS database.Fabrication and properties of composite sheet– The fine particles were mixed with the epoxy resin at a volume ratio of about 50%. This mixed solution was dropped onto a polymer sheet and screen-printed with a metal squeegee to a certain thickness, then a composite sheet was obtained. On the premise of mounting the composite in the gap between the interposer substrate and the IC chip, the coating thickness was chosen as 50 ± 5 μm in total. The Y-type fine particles were almost flat in planar state even after grinding and the Z-type and M-type fine particles were close to spherical and randomly oriented, according to the SEM observation. The coercive force obtained from the DC magnetization curve is 8 to 9 Oe in a composite sheet of Y-type and Z-type fine particles (hereinafter referred to as Y-type sheet, etc.), which is smaller by one order of magnitude than the M-type sheet (90 Oe). Correspondingly, the maximum value of the relative imaginary part permeability was the maximum of 1.8 for the Y-type sheet, and it was 0.9 for the Z-type sheet, and 0.3 for the M-type sheet. As shown in Fig. 1, measured input loss ratio [4] $\mathrm {P}_{{\mathrm {loss}}}/ \mathrm {P}_{{\mathrm {in}}}=1- ( \vert \mathrm {s}_{11} \vert ^{2}+\vert \mathrm {s}_{21} \vert ^{2})$with a network analyzer (Agilent Technologies, Model N5244A) became the larger as the relative imaginary part magnetic permeability became higher. The measured $\mathrm {P}_{\mathrm {loss}}/ \mathrm {P}_{\mathrm {in}}$was as high as 0.21 at 6 GHz, which should correspond to more than 5 dB conduction noise suppression. This research was supported in part by the R&D program of the Radio Use, Ministry of Internal Affairs and Communications, and the Cooperative Research Project Program of the RIEC (H27-B05) Tohoku University.

Davydov splitting and polytypism in few-layer MoS2

The dependence of the interlayer interaction on the stacking order of MoS2 is investigated by Raman spectroscopy using three excitation energies of 2.81, 2.41, and 1.96 eV. The low-frequency Raman spectra show distinct correlation with the stacking type. The A-like intra-layer vibration mode at 405 cm−1 exhibit Davydov splitting due to interlayer interactions when the 1.96 eV excitation is used. The positions and the relative intensities of the Davydov-split peaks depend on the stacking type as well. By using the linear-chain model, the interlayer force constants are extracted and compared for 3-layer samples with different stacking types: the 3R-types have a larger force constant than the 2H-type. For the 2H-type, Davydov splitting is analyzed as a function of the number of layers. The force constants for the second-nearest-neighbor interaction are obtained and compared with other transition metal dichalcogenides.

Improving accuracy of peak-pair intensity ratio measurement in differential chemical isotope labeling LC–MS for quantitative metabolomics

High-performance chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC–MS) has become a powerful platform for quantitative metabolomic analysis. With differential isotope labeling of individual samples (e.g., 12C2-labeling) and a control sample (e.g., 13C2-labeling), the resulting mixtures (12C2-labeled sample and 13C2-labeled control) can be analyzed using LC–MS to detect peak pairs of labeled metabolites from which the peak-pair intensity ratios can be measured to provide the basis of relative quantification of metabolites in different samples. Depending on the mass difference of the light and heavy reagents used and the number of reagent tags attached to a metabolite, the mass difference within a peak pair can be as low as 2 Da. With 2-Da difference, the natural isotopologue of the light labeled molecular ion can overlap with that of the heavy labeled molecular ion of the same metabolite, causing potential interference in the measurement of the heavy peak intensity. In this work, we report our study of the natural isotope relative peak intensity of the most common elements in human endogenous metabolites, including carbon, hydrogen, oxygen, nitrogen, phosphor and sulfur, and their contributions to the intensity of the 2-Da-heavier labeled peak. We propose a simple data processing method to estimate and remove the natural isotope interference for improving the measurement accuracy of peak-pair intensity ratios.