Simultaneous detection of different probe molecules using silver nanowires as SERS substrates.

Metallic silver nanowires with high yield were synthesized using a modified seed mediated approach at room temperature. Ribbon-like nanostructures were obtained when the concentration of NaOH was lower and further increase of NaOH transformed it into long nanowires. These nanowires possess high aspect ratio, with length and diameter ~6.5 µm and 17 nm respectively. The surface enhanced Raman scattering activity of these nanowires was tested with three different probe molecules viz., crystal violet, malachite green and nile blue chloride using visible (514.4 nm) and near-infrared (784.8 nm) excitation lines. The minimum detection limits for crystal violet and nile blue chloride molecules were found to be down to 10-7 M with good linear responses, as evidenced by values of correlation coefficients, indicating their potential for a variety of applications such as sensing. Principal component analysis was performed with the surface enhanced Raman spectra in order to discriminate the dye molecules and their mixture, simultaneously. The first two principal components, which provided 69.80 and 27.93% of the total data variance, could be conveniently represented as a two dimensional PCA score plot. The score plot showed clear clustering of probe molecules and their mixture. The relative contribution of wavenumbers to each of the two principal components was identified by plotting the PCA loading matrix. These results further promote possibilities of quantification of multiplexed SERS detection and analysis.

Luminescence analysis of SrGa2 Si2 O8 : RE3+ (RE = Dy, Tm) phosphors.

This article reports on the luminescence properties of rare earth (Dy3+ and Tm3+ )ions doped SrGa2 Si2 O8 phosphor were studied. SrGa2 Si2 O8 phosphors weresynthesizedby employing solid state reaction method.From the measured X-ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ-ray irradiated samples have been studied. Photoluminescence spectra of Dy3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 348 nm,and it shows two emission bands at 483 and 574 nm due to 4 F9/2  â†’ 6 H15/2 and 4 F9/2  â†’ 6 H13/2 transitions respectively. Whereas the photoluminescence spectra of Tm3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 359 nm and it exhibits two emission bands at 454 and 472 nm due to 1 D2  â†’ 3 F4 and1 G4  â†’ 3 H6 transitions respectively. In thermoluminescence study, γ-irradiatedthermoluminescence glow curve of SrGa2 Si2 O8 :Dy3+ phosphor shows two well defined peaks at 293 °C (peak1)and 170 °C (peak2) whereas thermoluminescence glow curve of SrGa2 Si2 O8 :Tm3+ phosphor shows peaks at 292 °C (peak1) and 184 °C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa2 Si2 O8 :Dy3+ and SrGa2 Si2 O8 :Tm3+ are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd.

Experimental and theoretical study of mechanoluminescence and lyoluminescence of Li3 PO4 : RE (RE = Dy and Tb) phosphors.

Li3 PO4 phosphors prepared by solid-state diffusion technique and lyoluminescence (LL) as well as mechanoluminescence (ML) studies are reported. Dy- and Tb-activated phosphors show dosimetric characteristics using LL and ML techniques. The energy levels and hence trapping and detrapping of charge carriers in the material can be studied using ML. Li3 PO4 phosphor can be used in the dosimetric applications for ionizing radiation. By using the LL technique, the LL characteristics of Li3 PO4 may be useful for high radiation doses. We also report a more detailed theoretical understanding of the mechanism of LL and ML.

Systematic study of photoluminescence, lyoluminescence and mechanoluminescence in Ce3+ - and Eu3+ -activated Li3 PO4 phosphors.

Li3 PO4 phosphor was prepared using a modified solid-state diffusion technique. In this work, photoluminescence, lyoluminescence and mechanoluminescence studies were carried out in a Li3 PO4 microcrystalline powder doped with different rare earths. In photoluminescence studies, characteristic emission of Ce and Eu was observed. The lyoluminescence glow curves of Li3 PO4 microcrystals show that lyoluminescence intensity initially increases with time and then decreases exponentially. The decay time consists of two components for all masses. The dependence of decay time, especially the longer component, on mass has been investigated. Experiments on γ-irradiated crystals have proved that the light emission originates from the recombination of released F-centres with trapped holes (V2-centres) at the sulfuric acid-solid interface. Incorporation of bivalent alkali in solid lithium phosphate leads to an enhancement of lyoluminescence. A possible explanation for the experimental results has been attempted. The phosphor has a mechanoluminescence single glow peak. Mechanoluminescence intensity under various loading conditions was investigated. It is observed that mechanoluminescence intensity increases with increasing impurity concentration and increasing piston impact velocity. The results may be considered as only being of academic interest in solid-state materials.

Macrocompression and nanoindentation of soft viscoelastic biological materials.

The study of the mechanical behavior of soft biological materials presents many challenges due to the materials' time-dependent mechanical response as well as inherent size and shape limitations. In this study, by using agar as a surrogate material for soft tissues, the effects of these limitations upon standardized macroscale dynamic compression protocols are compared to dynamic nanoindentation procedures. Both techniques are then applied to dynamically test porcine sclera tissue, showing a significant difference in recorded loss and storage modulus values between the two methodologies. Additionally, the tissues of the porcine eye wall are characterized with macrocompression in their layered in vivo arrangement. The overall constraints of standardized macroscale tests for dynamic mechanical characterization of thin and soft biological tissues are discussed.

Elastic and viscoelastic characterization of agar.

Agar is a biological polymer, frequently used in tissue engineering research; due to its consistency, controllable size, and concentration-based properties, it often serves as a representative material for actual biological tissues. In this study, nanoindentation was used to characterize both the time-independent and time-dependent response of agar samples having various concentrations (0.5%-5.0% by weight). Quasi-static indentation was performed at different loads and depths using both open- and closed-loop controls. Reduced modulus (Er) values change with agar concentration, ranging from ∼30 kPa for 0.5% samples to ∼700 kPa for 5.0% samples, which is the same modulus range as usually encountered in soft biological materials. Dynamic indentation was performed to assess the effects of load, dynamic frequency and amplitude. Storage modulus values ranged from approximately 30 to 2300 kPa depending on agar concentration. Loss modulus remained consistently less than 30 kPa at all conditions, indicating a diminished damping response in agar.

Studies on the mass and temperature dependence of lyoluminescence intensity of microcrystalline powder of KCl.

The temperature and mass dependence of lyoluminescence intensity of γ-irradiated colored potassium chloride powder have been studied using a photomultiplier tube connected to an x-y recorder. The peak lyoluminescence intensity increases with increasing amount of solute added up to 50 mg and then tends to saturate. The lyoluminescence (LL) glow curves with mass of KCl microcrystals show that initially the LL intensity increases with time and then decreases exponentially with time. The decay time consists of two components for all the masses. The dependence of decay time, especially the longer component on mass, has been investigated. The temperature dependence of LL intensity shows that initially the peak LL intensity increases with temperature up to 60°C, and then decreases with further increase in temperature. The decay time tends to decrease with increasing temperature. An explanation for the experimental results has been attempted.

Spectroscopic and thermal analysis of a submandibular sialolith of Wharton's duct resected using Nd:YAG laser.

A sialolith observed in the Wharton's duct of a male patient was resected using an Nd:YAG laser. This is the first report on the resection of sialolith using laser. The resected sample was analyzed for structural details using Fourier transform infrared (FTIR), FT-Raman, and fluorescence spectroscopic techniques. Other techniques like energy dispersive X-ray analysis, scanning electron microscopy, and thermal analysis were also used for the analysis of structural details. The major peaks of the vibrational spectra are observed to be due to the vibrations of the phosphate and hydroxyl groups of the inorganic part of the sample and the proteinaceous component of the organic part. The major elements in the sample are identified as calcium and phosphorous in the ratio 7:3. The fluorescence spectra recorded at excitation wavelengths 280, 325, and 410 nm showed emission maxima corresponding to the endogenous fluorescence of structural proteins and amino acids. The inorganic part of the sialolith remained stable even at temperatures up to 1,673 K. The spectroscopic studies indicated that the structure of the sialolith is similar to that of the dentine part of the human teeth. In situ disintegration of the sialolith involves very high temperature. High calcium and phosphorous content in the food may be attributed to one of the reasons for the formation of sialoliths.

Vibrational spectra of mono, di and trimethyl ammonium double sulphates of rare earths Pr, Nd, Ho and Eu.

Infrared and Raman spectra of four rare earth (Ho, Eu, Nd and Pr) double sulphates have been recorded and analysed based on the vibrations of methyl ammonium cations, sulphate anions and water molecules. Formation of hydrogen bonds of the type N-H...O and O-H...O are identified in all the compounds. Bifurcated hydrogen bonds are present in the compounds with dimethyl ammonium cations. The sulphate anions are distorted and occupy a lower site symmetry in the compounds. The bands obtained for (CH(3))(2)NH(2) and SO(4)(2-) ions indicate that the structural bonding of (CH(3))(2)NH(2)Eu(SO(4))(2).H(2)O and (CH(3))(2)NH(2)Ho(SO(4))(2).4H(2)O is identical. Electronic transition bands of Eu(3+) and Nd(3+) observed in the Raman spectra of these two compounds have been identified and discussed.

Temperature dependent polarized Raman spectra of nonaaqualanthanoid (Pr) single crystal.

Polarized Raman spectral changes with respect to temperature were investigated for Pr(BrO3)3.9H2O single crystals. FTIR spectra of hydrated and deuterated analogues were also recorded and analysed. Temperature dependent Raman spectral variation have been explained with the help of the thermograms recorded for the crystal. Factor group analysis could propose the appearance of BrO3 ions at sites corresponding to C3v (4) and D3h (2). Analysis of the vibrational bands at room temperature confirms a distorted C3v symmetry for the BrO3 ion in the crystal. From the vibrations of water molecules, hydrogen bonds of varying strengths have also been identified in the crystal. The appearance upsilon1 mode of BrO3- anion at lower wavenumber region is attributed to the attachment of hydrogen atoms to the BrO3- anion. At high temperatures, structural rearrangement is taking place for both H2O molecule and BrO3 ions leading to the loss of water molecules and structural reorientation of bromate ions causing phase transition of the crystal at the temperature of 447 K.

Raman and FTIR spectra of [Cu(H2O)6](BrO3)2 and [Al(H2O)6](BrO3)3 x 3H2O.

Raman and FTIR spectra of [Cu(H2O)6](BrO3)2 and [Al(H2O)6](BrO3)3 x 3H2O are recorded and analyzed. The observed bands are assigned on the basis of BrO3- and H2O vibrations. Additional bands obtained in the region of v3 and v1 modes in [Cu(H2O)6](BrO3)2 are due to the lifting of degeneracy of v3 modes, since the BrO3- ion occupies a site of lower symmetry. The appearance v1 mode of BrO3- anion at a lower wavenumber (771 cm(-1)) is attributed to the attachment of hydrogen to the BrO3- anion. The presence of three inequivalent bromate groups in the [Al(H2O)6](BrO3)3 x 3H2O structure is confirmed. The lifting of degeneracy of v4 mode indicates that the symmetry of BrO3- anion is lowered in the above crystal from C3v to C1. The appearance of additional bands in the stretching and bonding mode regions of water indicates the presence of hydrogen bonds of different strengths in both the crystals. Temperature dependent Raman spectra of single crystal [Cu(H2O)6](BrO3)2 are recorded in the range 77-523 K for various temperatures. A small structural rearrangement takes place in BrO3- ion in the crystal at 391 K. Hydrogen bounds in the crystal are rearranging themselves leading to the loss of one water molecule at 485 K. This is preceded by the reorientation of BrO3- ions causing a phase transition at 447 K. Changes in intensities and wavenumbers of the bands and the narrowing down of the bands at 77 K are attributed to the settling down of protons into ordered positions in the crystal.

Infrared and polarized Raman spectra of (CH3)2NH2Al(SO4)2 x 6H2O.

FTIR and single crystal Raman spectra of (CH3)2NH2Al(SO4)2 x 6H2O have been recorded at 300 and 90 K and analysed. The shifting of nu1 mode to higher wavenumber and its appearance in Bg species contributing to the alpha(xz) and alpha(yz) polarizability tensor components indicate the distortion of SO4 tetrahedra. The presence of nu1 and nu2 modes in the IR spectrum and the lifting of degeneracies of nu2, nu3, and nu4 modes are attributed to the lowering of the symmetry of the SO4(2-) ion. Coincidence of the IR and Raman bands for different modes suggest that DMA+ ion is orientationally disordered. One of the H atoms of the NH2 group of the DMA+ ion forms moderate hydrogen bonds with the SO4(2-) anion. Al(H2O)6(3+) ion is also distorted in the crystal. The shifting of the stretching modes to lower wavenumbers and the bending mode to higher wavenumber suggest that H2O molecules form strong hydrogen bonds with SO4(2-) anion. The intensity enhancement and the narrowing of nu1SO4, deltaC2N and Al(H2O)6(3+) modes at 90 K confirm the settling down of the protons in the hydrogen bonds formed with H2O molecules and NH2 groups. This may be one of the reasons for the phase transition observed in the crystal.

Good names. Market research reveals semantic differences in common health care names.

Using a research technique that combines a quantitative method adapted from linguistic science and conventional qualitative methods, the authors explore consumers' understanding of key terms--"primary care" vs. "family care," "hospital" vs. "medical center," and "aesthetic" vs. "cosmetic"--used in names for health care services. Their results reveal semantic differences that clearly point to names that optimally position these medical services in the local and regional marketplace.

Pregnancy induced hypertension and antithrombin-III.

This study was undertaken to determine the coagulation profile of women with pregnancy induced hypertension and to evaluate the changes in the level of AT-III in pre-eclampsia and eclampsia and its correlation with severity of disease in order to evaluate if it can be used as a marker for severity of PIH. 119 women with PIH in the third trimester of pregnancy constituted the study group. Age and parity matched 25 normal pregnant and 25 non-pregnant women were taken as control group. No significant difference between the coagulation profile of non-pregnant and normal pregnant women was seen. There is evidence of consumption coagulopathy in PIH patients and AT-III activity shows a gradual and almost linear reduction in various groups ranging from normal pregnant women to eclampsia. Reduction in AT-III activity has positive correlation with PIH and it can be a useful marker for severity of PIH.