Surface-enhanced Raman scattering (SERS) greatly improves molecule sensitivity compared with ordinary Raman spectroscopy. To excite and detect SERS efficiently, we fabricated glass-made microcapillary tubes decorated with silver nanoparticles inside them. The capillary tubes work as sample containers, where the required sample volume is in the order of a few nanoliters.
View Article and Find Full Text PDFBecause of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.
View Article and Find Full Text PDFDirect laser writing (DLW) via two-photon polymerization (TPP) has been established as a powerful technique for fabrication and integration of nanoscale components, as it enables the production of three dimensional (3D) micro/nano objects. This technique has indeed led to numerous applications, including micro- and nanoelectromechanical systems (MEMS/NEMS), metamaterials, mechanical metamaterials, and photonic crystals. However, as the feature sizes decrease, an urgent demand has emerged to uncover the mechanics of nanosized polymer materials.
View Article and Find Full Text PDFDirect laser writing through two-photon polymerization lithography is used to fabricate 3D nanostructures containing aligned single-wall carbon nanotubes (SWCNTs). SWCNTs are aligned in the laser scanning directions while they are embedded in the structure. The alignment is induced by spatial confinement, volume shrinkage, and the optical gradient force.
View Article and Find Full Text PDFPurpose: The purpose of this study was to show the effectiveness of combining intra-arterial infusion and systemic chemotherapy with concurrent radiotherapy for treatment of stage IV mandibular gingival cancer.
Materials And Methods: A total of 23 patients with mandibular gingival cancer were treated with either docetaxel by intra-arterial infusion followed by systemic chemoradiotherapy with cisplatinum and 5-fluorouracil as a monthly regimen, or with docetaxel and cisplatinum by intra-arterial infusion followed by systemic chemoradiotherapy with 5-fluorouracil as a weekly or biweekly regimen. Tumor responses, locoregional control, overall survival, disease-specific survival, and adverse events were evaluated.
We demonstrate fabrication of Au nanorod aggregates microstructures by means of a femtosecond near-infrared laser. The laser light was tightly focused into colloidal Au nanorods dispersed in photopolymerizable metyl-methacrylate (MMA) compound to induce two-photon polymerization (TPP). TPP of MMA glued the nanorods together to form solid microstrucures of aggregates.
View Article and Find Full Text PDFA remarkable recent progress in two-photon photopolymerization is the achievement of fabrication resolution around tens of nanometers, establishing a femtosecond laser as a nanofabrication tool. However, how the superresolution has been made possible is still under arguement. We propose a concept of polymer network permeability to solvents, meaning a structure-loosened nanopolymer state that allows free penetration of small molecules to interpret the mechanism.
View Article and Find Full Text PDFThroat swab specimens collected from 439 patients with influenza-like symptoms visiting a clinic in the 2004-2005 influenza season were subjected to cell culture virus isolation and viral antigen detection using a rapid diagnostic kit, QuickVue Rapid SP influ (Quidel Corporation, San Diego, CA, U.S.A.
View Article and Find Full Text PDFWe demonstrate the selective aggregation of single-walled carbon nanotubes by photon forces, using the large optical field gradient of a laser focused through a high numerical aperture objective lens. The nanotubes, dispersed in an aqueous solution with a surfactant, are detected via Raman scattering from the confocal volume of the optical trap. By using a visible-light laser for both trapping and detection, the dynamics of the radial breathing mode signal taken at short intervals shows an increase of a single breathing mode over time, indicating the increase in the density of only one species of tube in the focal volume.
View Article and Find Full Text PDFThe probability to realize a full photonic band gap in two-dimensional birefringent photonic crystals can be readily manipulated by introducing symmetry reduction or air holes in the crystal elements. The results lie in either creation of new band gaps or enlargement of existing band gaps. In particular, a combination of the two processes produces an effect much stronger than a simple summation of their individual contributions.
View Article and Find Full Text PDFWe present the first report of two-photon induced plastic surface deformation in solid polymer films. Exposure of azo polymer films, which absorb in the visible range (lambda(max) = 480 nm), to intense 920 nm irradiation leads to polarization dependent photofluidic polymer nanomovement caused by photoselective two-photon trans <-->cis isomerization. The deformations were induced by a gradient of light intensity; and strongly depend on the wavelength and the polarization direction of the incident laser light and the position of the focused spot with respect to the plane of the polymer film.
View Article and Find Full Text PDFWe studied the effect of changing temperature on the mechanical properties of nanosized poly(methyl methacrylate) wires fabricated by two-photon fabrication. At around room temperature, the nanowires showed a transition temperature where the shear modulus suddenly changed. This transition temperature was observed to decrease more than 40 K by decreasing the radius of the nanowires from 450 to 150 nm.
View Article and Find Full Text PDFTwo- and three-dimensional (2D and 3D) micro/nanostructures of CdS-polymer nanocomposites have been successfully patterned, combining photopolymerization via a laser four-beam interference technique with in situ synthesis of CdS nanoparticles in the patterned polymer matrix. The morphology and optical properties of CdS nanoparticles in polymer matrices have been confirmed using TEM, XRD, FTIR, UV-vis absorption and fluorescence spectroscopy. Laser irradiation time and film thickness are certified to be the key factors for the control of the micro/nanostructures.
View Article and Find Full Text PDFWe study the optically induced growth and interaction of self-written waveguides in a photopolymerizable resin. We investigate experimentally how the interaction depends on the mutual coherence and the relative power of the input beams and suggest an improved analytical model that describes the growth of single waveguides and the main features of their interaction in photosensitive materials.
View Article and Find Full Text PDFWe present laser interference patterning of three-dimensional photonic lattice structures with three-step three-beam irradiation. In contrast to one-step four-beam interference patterning, the proposed method makes it possible to continuously tune the lattice constant and the photonic band gap without distortion of the lattice shape. We analytically show that all fourteen Bravais lattices are possible to be produced by choosing proper incident vectors of laser beams.
View Article and Find Full Text PDFAs a well-established laser fabrication approach, holographic lithography, or multibeam interference patterning, is known for its capability to create long-range ordered large-volume photonic crystals (PhCs) rapidly. Its broad use is, however, hampered by difficulty in inducing artificially designed defects for device functions. We use pinpoint femtosecond laser ablation to remove and two-photon photopolymerization to add desired defective features to obtain photonic acceptors and photonic donors, respectively, in an otherwise complete PhC matrix produced by holographic lithography.
View Article and Find Full Text PDFWe investigated the antibacterial activity of 12 antibiotics, including 4 carbapenems, against 200 strains of respiratory pathogens isolated in 1997, and compared the results with those obtained in 1993. The strains examined were 38 strains of methicillin-susceptible Staphylococcus aureus (MSSA), 32 strains of methicillin-resistant S. aureus (MRSA), 22 strains of penicillin-susceptible Streptococcus pneumoniae (PSSP), 10 strains of penicillin-resistant S.
View Article and Find Full Text PDFThe in vitro antimicrobial activity of gatifloxacin against clinical isolates of pathogenic bacteria was evaluated. Minimum inhibitory concentrations of gatifloxacin, ofloxacin, ciprofloxacin, tosufloxacin, sparfloxacin, and rifampicin against 20 strains each of methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa, 18 strains of Enterobacter cloacae, 15 strains each of Streptococcus Pneumoniae and Moraxella catarrhalis, 12 strains of Haemophilus influenzae, 18 strains of Mycobacterium intracellulare, and 22 strains each of Mycobacterium tuberculosis and Mycobacterium avium were determined. The minimum inhibitory concentrations90's of gatifloxacin against the above species were 0.
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