pH SENSING AND IMAGING WITH NANOPARTICLES AND IMPLANTABLE FILMS

pH is a very important parameter in biological systems. Monitoring pH in situ may provide useful information for studying pH regulated cellular events, diagnosing diseases and assessing treatment efficacy. Various strategies have been introduced for developing pH sensors. However, it is still challenging to monitor pH in biological systems with high specificity, especially through thick tissue. In this dissertation, we describe three types of pH sensors which are used to noninvasively monitor pH in living cells, monitor and map bacterial growth caused pH variation through thick tissue with minimal autofluorescence background. In Chapter 2, a pH nanosensor with high specificity and sensitivity is developed based on surface-enhanced Raman scattering by encapsulating 4-mercaptobezonic acid functionalized silver nanoparticles in a proton permeable silica shell. The performance of silica protected nanosensor against aggregation and biomolecular interference is investigated. The nanosensors are introduced to report intracellular pH in living macrophages. In Chapter 3, a pH sensor film is designed for monitoring pH variation on a surface through thick tissue in real time. The pH sensor film is composed of a film of upconverting nanoparticles which functions as a local light source and a thin layer of pH indicator which modulates the luminescence in a pH dependent way. Upconverting nanoparticles are excited by near infrared laser (980 nm) which allows high tissue penetration depth and avoids autofluorescence from tissue. The pH sensor film is applied to monitor bacterial growth caused pH decrease at the interface of sensor film and trypic soy agar in real time through 6 mm porcine tissue. In Chapter 4, a pH sensor film with the ability to image pH variation through thick tissue with high spatial resolution is designed utilizing X-ray radioluminescent particles as a local light source. pH calibration curves are generated by taking the ratio of peak intensity at 620 nm over that at 700 nm. By creating a localized reference region on the sensor film, the tissue effect on the ratio of the two peaks is adjusted. The pH sensor film is used to monitor bacterial growth and study antibiotic effect with millimeter of spatial resolution which is primarily determined by the width of the X-ray beam. Both upconverting luminescence and X-ray radioluminesce based pH sensors have the potential to revolutionize the ability to diagnose and assess treatment for implanted medical devices associated bacterial infection

二段階ボールミリングプロセスによるCu-Ti-C合金の開発

要約のみTohoku University千葉晶彦課

Micro-modulated luminescence tomography

Imaging depth of optical microscopy has been fundamentally limited to millimeter or sub-millimeter due to light scattering. X-ray microscopy can resolve spatial details of few microns deeply inside a sample but the contrast resolution is still inadequate to depict heterogeneous features at cellular or sub-cellular levels. To enhance and enrich biological contrast at large imaging depth, various nanoparticles are introduced and become essential to basic research and molecular medicine. Nanoparticles can be functionalized as imaging probes, similar to fluorescent and bioluminescent proteins. LiGa5O8:Cr3+ nanoparticles were recently synthesized to facilitate luminescence energy storage with x-ray pre-excitation and the subsequently stimulated luminescence emission by visible/near-infrared (NIR) light. In this paper, we suggest a micro-modulated luminescence tomography (MLT) approach to quantify a nanophosphor distribution in a thick biological sample with high resolution. Our numerical simulation studies demonstrate the feasibility of the proposed approach.Comment: 8 pages, 2 figures, 31 reference

Three new species of the Fannia serena species subgroup from China (Diptera: Fanniidae)

The Fannia serena species group (Diptera: Fanniidae) ismainly distributed in the Holarctic region and comprises four subgroups with a total of 32 species. Three new species of the Fannia serena-subgroup, Fannia aureomarginata Wang et Cheng, sp. n., F. suberemna Wang, sp. n. and F. wui Wang, sp. n., are described from China. An identification key to all known species of the Fannia serena-subgroup is also provided

Crustal structure and deformation beneath the NE margin of the Tibetan plateau constrained by teleseismic receiver function data

We analysed a large amount of teleseismic receiver function data recorded by 172 broadband stations in the NE Tibetan plateau and its surrounding areas to investigate the crustal velocity and anisotropy structure beneath the margin. We first applied the modified H–κ stacking technique to measure the crustal thickness and average Vp/Vs ratio, and then employed a joint inversion scheme to measure azimuthal anisotropy of the crust beneath each station. The observed crustal thickness and Vp/Vs ratio exhibit large variations across the study area, varying from 32 to 75.6 km and from 1.601 to 1.864, respectively. We also found significant azimuthal anisotropy within the crust beneath 12 stations, with a splitting time between 0.36 and 1.06s. The fast polarization directions align well with surface structures, and follow the directions of the maximum horizontal tensile stress. The low Vp/Vs ratio and the strong azimuthal anisotropy observed beneath the margin suggest that whole crustal shortening might be the dominant mechanism for producing the thick crust in NE Tibet. We compared the measured seismic anisotropy with those measured from XKS (SKS, PKS and SKKS), and found that crustal anisotropy appears to play an important role in explaining the amount of XKS splitting times. More importantly, the Moho Ps and the XKS share similar fast polarization directions, suggesting a vertically coherent deformation within the lithosphere beneath the margin