Support Theorems and an Injectivity Result for Integral Moments of a Symmetric m-Tensor Field

In this work, we show an injectivity result and support theorems for integral moments of a symmetric m-tensor field on a simple, real analytic, Riemannian manifold. Integral moments of symmetric m-tensor fields were first introduced by Sharafutdinov. First we generalize a Helgason type support theorem proven by Krishnan and Stefanov (Inverse Probl Imaging 3(3):453–464, 2009). We use this extended result along with the first integral moments of a symmetric m-tensor field to prove the aforementioned results.

     

Pertraction of U(VI) through liquid membranes using monoamides as carrier ligands: experimental and theoretical studies

Pertraction of U(VI) from HNO₃ feed into water through flat-sheet supported liquid membrane containing a series of monoamides, viz. N,N-dihexylhexanamide (DHHA), N,N-dihexyloctanamide (DHOA) and N,N-dihexyldecanamide (DHDA), as the carrier ligands were studied. The results obtained with monoamides were compared with those obtained with TBP, a contemporary ligand to monoamides. The permeation of U(VI) was primarily governed by the distribution ratio of U(VI) by the ligands. A mathematical equation was derived by solving the mass balance equation on the feed side and the receiver side of the membrane which fitted well to a series of experimental results in the present work.

     

Design and Development of Axially Chiral Bis(naphthofuran) Luminogens as Fluorescent Probes for Cell Imaging

Designing chiral AIEgens without aggregation-induced emission (AIE)-active molecules externally tagged to the chiral scaffold remains a long-standing challenge for the scientific community. The inherent aggregation-caused quenching phenomenon associated with the axially chiral (R)-[1,1′-binaphthalene]-2,2′-diol ((R)-BINOL) scaffold, together with its marginal Stokes shift, limits its application as a chiral AIE-active material. Here, in our effort to design chiral luminogens, we have developed a design strategy in which 2-substituted furans, when appropriately fused with the BINOL scaffold, will generate solid-state emissive materials with high thermal and photostability as well as colour-tunable properties. The excellent biocompatibility, together with the high fluorescence quantum yield and large Stokes shift, of one of the luminogens stimulated us to investigate its cell-imaging potential. The luminogen was observed to be well internalised and uniformly dispersed within the cytoplasm of MDA-MB-231 cancer cells, showing high fluorescence intensity.     

Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m². The most efficient green PhOLED with 10 wt% of Ir(ppy)₃ {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m², which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.     

Observation of memory behaviour in cadmium sulphide nanorods doped ferroelectric liquid crystal mixture

In this study, cadmium sulphide (CdS) nanorods doped ferroelectric liquid crystal (FLC) sample cells have been prepared and studied. A memory effect has been observed in CdS nanorods (≤0.3?wt%) doped FLC mixture and confirmed by textures, dielectric and optical studies. The addition of nanorods increases the memory behaviour and efficiency. The occurrence of memory behaviour has been explained due to charge transfer from liquid crystal molecules to CdS nanorods and exists there for 5–15?min in 0.1–0.3?wt% CdS nanorods doped samples. An improvement in polarization, switching time, threshold voltage and rise time parameters has also been noticed in CdS nanorods doped FLC samples.     

Sonochemical effect on size reduction of CaCO3 nanoparticles derived from waste eggshells

A novel combination of mechanochemical and sonochemical techniques was developed to produce high-surface-area, bio-based calcium carbonate (CaCO₃) nanoparticles from eggshells. Size reduction of eggshell achieved via mechanochemical and followed by sonochemical method. First, eggshells were cleaned and ground, then ball milled in wet condition using polypropylene glycol for ten hours to produce fine particles. The ball milled eggshell particles were then irradiated with a high intensity ultrasonic horn (Ti-horn, 20 kHz, and 100 W/cm²) in the presence of N,N-dimethylformamide (DMF); decahydronaphthalene (Decalin); or tetrahydrofuran (THF). The ultrasonic irradiation times varied from 1 to 5 h. Transmission electron microscopic (TEM) studies showed that the resultant particle shapes and sizes were different from each solvent. The sonochemical effect of DMF is more pronounced and the particles were irregular platelets of ～10 nm. The BET surface area (43.687 m²/g) of these nanoparticles is much higher than that of other nanoparticles derived from eggshells.     

Determination of the mid-IR femtosecond surface-damage threshold of germanium

To assess the potential uses of germanium as a nonlinear material in the mid IR we have measured the surface-damage threshold of germanium optical windows using femtosecond pulses at a wavelength of 3.9 μm. By working with a wavelength corresponding to a photon energy of less than half the band-gap energy, free-carrier generation due to one- and two-photon absorption was eliminated. The laser pulses had an energy of 5.5 μJ, a duration of 255 fs, and were focused to a waist size of approximately 100 μm. The multi-shot damage threshold of the germanium windows was estimated to be approximately 94 GW/cm². The data should be of immediate benefit to industrial laser researchers and applications engineers working in the mid-IR region.     

Three-dimensional in silico breast phantoms for multimodal image simulations

Anatomic simulators have provided researchers with the realistic objects needed to develop and evaluate medical imaging approaches. Today we have new insights into the cellular biology of breast tissues that is driving many new targeted diagnostic and therapeutic approaches, including molecular imaging. We report on our initial efforts to build a scalable framework for the construction of realistic 3-D in silico breast phantoms (ISBP) capable of leveraging existing knowledge and yet adaptable to fully integrate future discoveries. The ISBP frames are developed with scalable anatomical shapes and morphologic features as adapted from a rich literature on this topic. Frames are populated with tissue subtypes essential for imaging and object contrast functions are assigned. These data can be resampled to match the intrinsics scales of various imaging modalities; we explore mammography, sonography and computed tomography. Initial comparisons between simulated and clinical images demonstrate reasonable agreement and provides guidance for future development of a more realistic ISBP. An end-to-end simulation of breast images is described to demonstrate techniques for including stochastic variability and deterministic physical principles on which image formation is based.     

Cell sorting by deterministic cell rolling

This communication presents the concept of "deterministic cell rolling", which leverages transient cell-surface molecular interactions that mediate cell rolling to sort cells with high purity and efficiency in a single step.     

Enhanced discrimination of DNA molecules in nanofluidic channels through multiple measurements

Nanofluidic sensing elements have been the focus of recent experiments for numerous applications ranging from nucleic acid fragment sizing to single-molecule DNA sequencing. These applications critically rely on high measurement fidelity, and methods to increase resolution are required. Herein, we describe fabrication and testing of a nanochannel device that enhances measurement resolution by performing multiple measurements (>100) on single DNA molecules. The enhanced measurement resolution enabled length discrimination between a mixture of λ-DNA (48.5 kbp) and T7 DNA (39.9 kbp) molecules, which were detected as transient current changes during translocation of the molecules through the nanochannel. As long DNA molecules are difficult to resolve quickly and with high fidelity with conventional electrophoresis, this approach may yield potentially portable, direct electrical sizing of DNA fragments with high sensitivity and resolution.