Magnetic Inversion Symmetry Breaking and Ferroelectricity in TbMnO\u3csub\u3e3\u3c/sub\u3e

TbMnO3 is an orthorhombic insulator where incommensurate spin order for temperature TN\u3c41  K is accompanied by ferroelectric order for T\u3c28  K. To understand this, we establish the magnetic structure above and below the ferroelectric transition using neutron diffraction. In the paraelectric phase, the spin structure is incommensurate and longitudinally modulated. In the ferroelectric phase, however, there is a transverse incommensurate spiral. We show that the spiral breaks spatial inversion symmetry and can account for magnetoelectricity in TbMnO3

Rapid Light-Driven Color Transition of Novel Photoresponsive Polydiacetylene Molecules

We developed new photoresponsive polydiacetylene (PR-PDA) molecules by incorporating a photocleavable moiety, 6-nitropiperonyl alcohol (NP) or 4,5-dimethoxy-2-nitrobenzyl alcohol (DMN), into a self-assembling diacetylene molecule. Inducing steric disordering of the assembled PDA molecules by the cleavage of the photoresponsive moiety under 365 nm UV irradiation results in color transition from blue to red and development of red fluorescence, allowing convenient photo patterning. Further writing and erasing of fluorescence patterns are demonstrated toward novel secure information communication and anticounterfeiting applications

Passive IoT Optical Fiber Sensor Network for Water Level Monitoring with Signal Processing of Feature Extraction

This paper presents a real-time remote water level monitoring system based on dense wavelength division multiplexing (DWDM)-passive optical fiber sensor (OFS) network for the application of the Internet of Things (IoT). This network employs a broadband light source based on amplified spontaneous emission (ASE) as a seed light. This ASE light is spectrum-sliced by an athermal type arrayed waveguide grating (200 GHz × 16 channel), then distributed towards multiple sensing units (SU). Here, 16 SUs are installed vertically at the specified height in the water pool according to the design specification (i.e., spatial resolution). Then, each SU reflects an optical spectrum having a different reflection coefficient depending on the surrounding medium (e.g., air or water). By measuring these reflected optical spectra with an optical spectrum analyzer, the water level can be easily recognized in real time. However, as the sensing distance increases, system performance is severely degraded due to the Rayleigh Back-Scattering of the ASE light. As a result, the remote sensing capability is limited at a short distance (i.e., <10 km). To overcome this limitation, we propose a simple signal processing technique based on feature extraction of received optical spectra, which includes embedding a peak detection algorithm with a signal validation check. For the specific, the proposed signal processing performs the peak power detection, signal quality monitoring, and determination/display of the actual water level through three function modules, i.e., data save/load module, signal processing module, and Human–Machine Interface display module. In particular, the signal quality of the remote sensing network can be easily monitored through several factors, such as the number of spectral peaks, the wavelength spacing between neighboring peaks and the pattern of detected peak power. Moreover, by using this validation check algorithm, it is also possible to diagnose various error types (such as peak detection error, loss of data and so on) according to the pattern of measured optical spectra. As a result, the IoT sensor network can recognize 17 different level statuses for the water level measurement from a distance of about 25 km away without active devices such as optical amplifiers (i.e., passive remote sensing)

Rücktitelbild: Tailoring Intermolecular Interactions for Efficient Room‐Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices (Angew. Chem. 42/2014)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109358/1/222211280_ftp.pd

Back Cover: Tailoring Intermolecular Interactions for Efficient Room‐Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices (Angew. Chem. Int. Ed. 42/2014)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109325/1/222211100_ftp.pd

Tailoring Intermolecular Interactions for Efficient Room-Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices

Herein we report a rational design strategy for tailoring intermolecular interactions to enhance room-temperature phosphorescence from purely organic materials in amorphous matrices at ambient conditions. The built-in strong halogen and hydrogen bonding between the newly developed phosphor G1 and the poly(vinyl alcohol) (PVA) matrix efficiently suppresses vibrational dissipation and thus enables bright room-temperature phosphorescence (RTP) with quantum yields reaching 24%. Furthermore, we found that modulation of the strength of halogen and hydrogen bonding in the G1-PVA system by water molecules produced unique reversible phosphorescence-to-fluorescence switching behavior. This unique system can be utilized as a ratiometric water sensorclos

Highly sensitive turn-on biosensors by regulating fluorescent dye assembly on liposome surfaces

We developed a new self-signaling sensory system built on phospholipid liposomes having H-aggregated R6G dyes on their surface. Selective molecular recognition of a target by the phospholipid displaces R6G from the liposome surface to turn on fluorescence signal. Selective and sensitive detection of neomycin down to 2.3 nM is demonstratedclos

Stimuli-Responsive Matrix-Assisted Colorimetric Water Indicator of Polydiacetylene Nanofibers

An alternative signal transduction mechanism of polydiacetylene (PDA) sensors is devised by combining stimuli-responsive polymer hydrogel as a matrix and PDA sensory materials as a signal-generating component. We hypothesized that volumetric expansion of the polymer hydrogel matrix by means of external stimuli can impose stress on the imbedded PDA materials, generating a sensory signal. PDA assembly as a sensory component was ionically linked with the alginate hydrogel in order to transfer the volumetric expansion force of alginate hydrogel efficiently to the sensory PDA molecules. Under the same swelling ratio of alginate hydrogel, alginate gel having embedded 1-dimensional thin PDA nanofibers (???20 nm diameter) presented a sharp color change while 0-dimensional PDA liposome did not give any sensory signal when it was integrated in alginate gel. The results implied that dimensionality is an important design factor to realize stimuli-responsive matrix-driven colorimetric PDA sensory systems; more effective contact points between 1-dimensional PDA nanofibers and the alginate matrix much more effectively transfer the external stress exerted by the volumetric expansion force, and thin PDA nanofibers respond more sensitively to the stress.clos

Dual-mode waveguiding of Raman and luminescence signals in a crystalline organic microplate

We demonstrate dual-mode waveguiding of Raman and luminescence signals using p-conjugated organic 1,4-bis(3,5-bis(trifluoromethyl) cyanostyryl)-2,5-dibromobenzene (CN-TSDB) microplates with singlecrystal structure. The output Raman and photoluminescence (PL) spectra through the CN-TSDB microplates were recorded as a function of propagation distance using a high-resolution laser confocal microscope (LCM). Under 633 nm Raman excitation, which is outside the optical absorption of the microplates, the characteristic Raman modes of C–Br, –CF3, and –C]C– aromatic stretching were clearly observed at the output points. The decay characteristics of the LCM Raman intensities were comparable to those of LCM PL intensities. The intermolecular p–p interaction of CN-TSDB has been enhanced by the attractive interaction between the CN group and Br atoms, which induces efficient polariton propagation and plays an important role in dual-mode waveguiding.111111sciescopu

Biomimetic detection of aminoglycosidic antibiotics using polydiacetylene-phospholipids supramolecules

We rationally designed highly sensitive and selective polydiacetylene (PDA)-phospholipids liposomes for the facile detection of aminoglycosidic antibiotics. The detecting mechanism mimics the cellular membrane interactions between neomycin and phosphatidylinositol-4,5-bisphosphate (PIP2) phospholipids. The developed PDA-PIP2 sensory system showed a detection limit of 61 ppb for neomycin and was very specific to aminoglycosidic antibodies only.close