Ring Length Research Articles

New host materials based on fluorene and benzimidazole units for efficient solution-processed green phosphorescent OLEDs

New green host materials 1-(9,9-diphenyl-9H-fluorene-2-yl)-2-phenyl-1H-benzimidazole and 1-(9,9′-spirobifluorene-2-yl)-2-phenyl-1H-benzimidazole for solution-processed green phosphorescent organic light-emitting devices have been designed and synthesized by attaching the electron transporting benzimidazole units to the rigid fluorene units. Owing to the non-planar structures, which decrease the π conjugation length of fluorene and benzimidazole rings, these fluorene derived derivatives show high triplet energy. The high triplet energy of newly host materials ensures efficient energy transfer from the host to the triplet emitter tris(2-phenylpyridine)iridium. Furthermore, the thermal, photophysical, electrochemical properties and crystal structures of 1-(9,9-diphenyl-9H-fluorene-2-yl)-2-phenyl-1H-benzimidazole and 1-(9,9′-spirobifluorene-2-yl)-2-phenyl-1H-benzimidazole were investigated. The solution-processed single-layer green device using 1-(9,9-diphenyl-9H-fluorene-2-yl)-2-phenyl-1H-benzimidazole as the host for the phosphorescence emitter tris(2-phenylpyridine)iridium showed the maximum luminance efficiencies of 10.1cd/A. This result demonstrated that the newly synthesized, fluorene-based rigid host materials are advantageous for fabrication of highly efficient green phosphorescent organic light-emitting diodes.

Xylem cell length under drought and its value for predicting radial growth of SRF poplar cultivars (Populus spp.)

Xylem cell length of juvenile tree rings was investigated in poplars in order to check the hypotheses that fiber length or vessel element length are indicative of drought tolerance and have predictive value for final stem base diameter at the end of rotation. The radial increment in the drought year 2003 served as the reference indicator for quantifying drought tolerance. All nine investigated cultivars suffered severely. In terms of their moderately decreased radial increment in 2003, the two aspen cultivars were clearly less drought susceptible than the seven hybrid poplar cultivars. The variance components of xylem cell length data explained by the two genetic factors ‘cultivar’ and ‘botanic section’ as well as the ‘tree ring’ (of the years 2002 and 2003) were compared by means of ANOVAs. The cultivar effects were superior to the effects of the critical precipitation status in 2003 and the botanic section. Fiber and vessel element length were found to be less sensitive to the drought compared with radial increment. They did neither correlate with radial increment in the drought year 2003 nor in 2002. Therefore, higher xylem cell length cannot indicate drought tolerance in poplars. However, a linear relationship between fiber length of both juvenile tree rings and the stem base diameter proved to be highly significant to a linear mixed effect model. Higher fiber length of a juvenile tree ring was considered to be predictive of larger stem base diameter at the end of rotation.

Deformation of the benzene ring upon fluorination: equilibrium structures of all fluorobenzenes

Born−Oppenheimer equilibrium structure (r BO e) estimates are reported for benzene and all 12 possible fluorobenzenes, based on geometry optimizations performed at the coupled cluster level of electronic structure theory including single and double excitations augmented by a perturbational estimate of the effects of connected triple excitations [CCSD(T)] and Gaussian basis sets of at least triple zeta quality. Furthermore, accurate semiexperimental equilibrium (r SE e) structures are determined for C6H6, C6H5F, and 1,2- and 1,3-difluorobenzene. They are obtained through a least-squares structural refinement procedure based on equilibrium rotational constants of as many isotopologues as feasible, determined by correcting experimental vibrationally averaged ground-state rotational constants with computed ab initio vibration–rotation interaction constants and electronic g-factors, and using a few structural constraints based on the best r BO e estimates. The r BO e and r SE e equilibrium structures are in excellent agreement with each other for the four semirigid molecules but in almost all cases they differ significantly from previously determined equilibrium structure estimates based on rotational spectroscopy or gas electron diffraction. The nature of deformations of the benzene ring induced by a single fluorine substitution can be characterized as follows: (a) the strongest effect is the pushing of the ipso carbon atom toward the ring center resulting in a deformation at the ipso [by +2.7(1)°] and ortho [−1.7(1)°] CCC angles, (b) a simultaneous decrease in the ortho CC bond length of the benzene ring by 0.009 Å and (c) a decrease of all the CH bond lengths. Additivity relations concerning the F substitution effects are obtained based on the equilibrium structures of all possible fluorobenzenes.

A comparative study on yarn hairiness results from manual test and two commercial hairiness metres

The true hairiness (actual hair number and length) of ring, compact and rotor spun yarns was measured by means of a tedious manual method. The hairiness results were then compared with yarn hairiness results obtained from two commercial instruments (Uster tester and Zweigle Hairiness Meter). The comparative analysis between the measurement methods has revealed very significant discrepancy between the true hairiness results and that from commercial instruments, not only just in terms of the number of hairs, but also in terms of the hair-length distribution. The hair numbers obtained from manual method are much greater than that obtained from the hairiness metres, and the true hair-length distribution does not follow the well-known exponential decay. This study shows that the two existing hairiness measuring systems, while essential for rapid assessment of yarn hairiness, are not accurately measuring the true hairiness of spun yarns.

Synthesis and Binding Properties of Arylethyne-Linked Porphyrin-Zinc Complexes for Organic Electronics Applications

Conjugated meso-alkynyl 5,15-dimesitylporphyrin metal complexes have been synthesized by Sonogashira coupling reaction in good yields. Alkynyl groups were chosen as a link at the meso positions in order to extend the pi-conjugated length of porphyrin rings. These synthesized porphyrin derivatives were characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry. Moreover, UV-visible spectroscopy and fluorescence spectroscopy were also used to investigate their photophysical properties. It has been demonstrated that central metal ions as well as meso substituents on porphyrin rings affected the electronic absorption and emission spectra of the compounds. Spectroscopic results revealed that alkyne-linked porphyrin metal complexes showed higher pi-conjugation compared with porphyrin building blocks resulting in red shifts in both absorption and emission spectra. Coordination properties of synthesized porphyrins were preliminarily investigated by UV-visible absorption and fluorescence emission spectroscopic titration with pyridine as axial ligand. The formation of porphyrin-pyridine complexes resulted in significant red shifts in absorption spectra and decrease of fluorescence intensity in emission spectra. Moreover, the 1H NMR titration experiments suggested that central metal ions play an important role to coordinate with pyridine and the coordination of porphyrin zinc(II) complex with pyridine occur in a 1:1 ratio. From these spectroscopic results, alkyne-linked porphyrin metal complexes offer potential applications as materials for optical organic nanosensors.

Effect of Cannabinoids and MethoxyPolyethylene Glycols on Aqueous Humor Outflow and Vascular Tone

WIN, a cannabinoid, and MPDTE, a methoxy polyethylene glycol are novel drugs to mitigate the increase in intraocular pressure, a major risk factor for glaucoma. However, their mechanism of action is not well studied. We investigate whether WIN or MPDTE reduce IOP by targeting vascular tone or reduced aqueous humor (AH) production and if eNOS is involved. To document AH flow using fluorometry, eyes were treated topically with either 1.0% WIN, 1.0% MPDTE, 0.1% brimonidine or brinzolamide 10 min prior to applying fluorescein. To measure vascular tone, 4mm aortic rings were placed on a weighted hook system and equilibrated in Krebs solution before introducing either 1.0% WIN or 1.0% MPDTE (n=5/group). Changes in the length of the bands were measured with a micrometer. To control for eNOS contribution, endothelial lining on aortic rings was either removed or kept intact. The greatest reduction in fluorescein intensity was observed after WIN treatment (73±13%) followed by brimonidine (55±10%), MPDTE (42±7%) and brinzolamide (39±4%). WIN increased ring length by 15±3% and MPDTE by 6±4% (p=0.01, n=5). In aortic rings without endothelium, WIN increased ring length by 8±4% and MPDTE by 5±3%. Preliminary results suggest that WIN targets AH outflow with some eNOS involvement while MPDTE targets AH production without affecting vascular tone. Supported in part by E. VA Eye Inst. and E. VA Med Sch.

Free vibration for an electromechanical integrated harmonic piezodrive system

The Authors propose an electromechanical integrated harmonic piezodrive system in which the piezodrive principle is combined with the harmonic drive and the movable tooth drive principles. The free vibration behavior of the flexible ring has important effects on operating performance of the drive system. Here, the dynamic equations for the harmonic piezodrive system are deduced. The natural frequencies and dynamic displacements of the drive system are investigated. Results show that a large length of the flexible ring, a small thickness of the flexible ring should be selected, and the flexible ring should be made with Cu in order to obtain better operating behavior of the drive system. These results are useful in design and manufacture of the drive system.

Effect of top stiffening rings of open top tanks on critical harmonic settlement

The purpose of this work is to investigate the effect of top stiffening rings of open top tanks on the critical harmonic settlement. First, the buckling behavior of a tank with a top stiffening ring is provided and the results are compared with that of the model with no stiffening ring. The results show that the critical harmonic settlement for the tank with a top stiffening ring is lower than that for the tank with no top stiffening ring. Moreover, the top stiffening ring plays a significant role on the critical harmonic settlement when the wave number is small, but plays a minor role on that when the wave number is large. Then, the imperfection sensitivity analysis is conducted to identify whether the top stiffening ring can decrease the sensitivity of imperfection. Meanwhile, the worst imperfection form for tanks subjected to harmonic settlement is reported. The results present that the weld depression has the most adverse effect on the settlement carrying capacity of tanks. Moreover, it is indicated that the top stiffening ring cannot always decrease the sensitivity of the imperfection. The sensitivity plots are related to harmonic wave numbers, as well as imperfection forms. Finally, the effect of top stiffening rings with different structure parameters on the critical harmonic settlement is reported, including the length and the thickness of the top stiffening ring. For the length of the top stiffening ring, the critical harmonic settlement versus the wave number decreases more and more slightly with the increasing length of the top stiffening ring. For the thickness of the top stiffening ring, the critical harmonic settlement versus the wave number decreases more and more mildly with the thickness of the top stiffening ring on the increase.

Widely Tunable Single Longitudinal Mode Fiber Laser With Cascaded Fiber-Ring Secondary Cavity

A widely tunable single longitudinal mode (SLM) fiber laser with cascaded Type I and Type II fiber ring secondary cavities, which uses a tunable fiber Bragg grating (FBG) as the mode-restricting and wavelength-tuning element, is proposed and demonstrated. Since the cascaded fiber rings can effectively expand the pass-band spacing to make the mode selection with the FBG easier, the stability of SLM oscillation can be improved by suitably optimizing the coupling ratio of optical couplers in Type II fiber ring to ensure that at least one and only one longitudinal mode dominates in the selected pass-band. When the fiber ring lengths are designed to make their expanded pass-band spacing be a value from 0.5 to 1 times of the 3-dB bandwidth of the FBG, the mode competitions between both neighboring pass-bands and main cavity modes, may be effectively eliminated, making the laser maintain mode-hop-free SLM oscillations while it is widely tuned.

Current modulation technique used in resonator micro-optic gyro

Resonator micro-optic gyro (RMOG) is a promising candidate for the next generation inertial rotation sensor based on the Sagnac effect. A current modulation technique used in an external cavity laser diode is proposed to construct the gyroscope system for the first time. The resonance curves before and after eliminating accompanying amplitude modulation are theoretically analyzed, calculated, and simulated; the demodulation curves with different modulation currents are formulated theoretically; and the optimum modulation current corresponding to the maximum sensitivity is obtained. The experiment results from the established RMOG experimental setup demonstrate that a bias stability of 2.7 deg/s (10 s integrated time) over 600 s, and dynamic range of ±500 deg/s are demonstrated in an RMOG with a silica optical waveguide ring resonator having a ring length of 12.8 cm.

Improving performance of a tandem simulated moving bed process for sugar separation by making a difference in the adsorbents and the column lengths of the two subordinate simulated moving bed units

A tandem simulated moving bed (SMB) process for removal of sulfuric acid and acetic acid from sugars has been developed previously. This process consisted of two four-zone SMB units (Ring I and Ring II), in which the same adsorbent (Dowex99 resin) and the same column length were used. To improve the performance of such a tandem SMB process for sugar separation, it is worth adopting the strategy of making a difference between the column lengths of Ring I and Ring II. The results showed that such strategy could allow the adsorbent beds of both Ring I and Ring II to be fully utilized at the same time, which was impracticable in the previous tandem SMB mode. As a result, the tandem SMB based on such strategy could achieve higher productivity than the previous tandem SMB mode. In addition, the use of different adsorbents (Amberchrom-CG161C in Ring I and Dowex99 in Ring II) was proposed as the second strategy, which was confirmed to be highly effective in improving the productivity of the tandem SMB for sugar separation. Finally, a third strategy was proposed by combing the first and the second strategies. It was found that compared to the previous tandem SMB mode, the third strategy led to more than eleven times the productivity under the constraint of pressure drop ≤100psi. This was mostly because the third strategy had a remarkable advantage over the previous tandem SMB mode in the aspects of bed utilization and selectivities, which stemmed from the use of different column lengths and the use of different adsorbents respectively.

Design of a Multimode Type Ring Vector Sensor

통상의 수중 음향 센서는 단일 센서로는 음압의 크기만 측정할 뿐 외부 음원의 방향은 측정 할 수 없는 한계가 있다. 이에 본 논문에서는 링 센서를 사용하여 음원의 방향을 찾을 수 있는 구조를 제안하였다. 제안된 구조의 링 센서는 내부 압전 세라믹이 8등분되어 배열되어 있으며, 외부 음압에 대한 각 압전 세라믹 조각의 출력 전압을 적절히 조합하여 외부 음원의 방향을 파악할 수 있는 특성을 가진다. 나아가 링 센서의 반경, 압전 세라믹의 두께, 길이와 같은 구조 변수들의 영향을 분석하여, 벡터 센서의 감도를 향상 시킬 수 있는 방안을 제시하였다. Typical underwater acoustic sensors can measure the scalar quantity of sound-pressure-magnitude with the limitation of being unable to identify the direction of an incoming wave. This paper proposes a method to detect the direction of the sound wave with a ring sensor. The sensor of the proposed structure has a piezoceramic ring divided into eight elements, and distinguishes the direction of the sound wave by properly combining the output voltages of the piezoceramic elements. Further, through the analysis of the effects of the structural parameters like the ring radius and length, and piezoceramic thickness, we have suggested the way to improve the sensitivity of the vector sensor.

Fiber optic gyroscope vibration error due to fiber tail length asymmetry based on elastic-optic effect

In the assembly of fiber optic gyroscope (FOG), the summation of the fiber tail length of waveguide and fiber ring in two directions cannot be exactly equal (i.e., fiber tail length of FOG in two directions is asymmetry). We analyze and calculate the vibration error of FOG due to this fiber tail length asymmetry based on elastic-optic effect. Inertial navigation simulation is performed to show attitude and positioning errors caused by this vibration error, which clearly shows the importance of reducing fiber-tail length asymmetry in high-accuracy applications.

Optical Coding for Next-Generation Survivable Long-Reach Passive Optical Networks

Optical coding has been proposed and has been well investigated for the monitoring of standard time domain multiplexing passive optical networks (TDM-PONs). We propose a physical layer fault management and protection system for next-generation passive optical networks, so-called long-reach PON (LR-PON), based on passive optical coding. Our approach exploits adapted, performance enhanced, and inexpensive passive optical components in the field, and electronic switches in the central office (CO). This allows detection and localization of the faulty segments in addition to the faulty nodes, hence decreasing the false alarm probability encountered in previous proposed approaches. We show that ring duplication protection in LR-PON can save almost half the cost compared with full duplication protection, with relatively high availability (99.992%). We describe the implementation strategy of our system in various well-known metro network topologies, including (1) single-ring-, (2) double-ring-, and (3) double-fiber-pairs-based ring topologies; all are considered different varieties of ring-and-spur LR-PON. The internal architecture of the remote nodes and the CO are also described in addition to the appropriate placement of our passive monitors. We develop two novel symmetric coding settings. We call them symmetrical optical encoders, which are suitable for fault detection and localization in the ring. We also develop the algorithms required to be executed by the network management system in the CO for fault detection, localization, and protection. Expressions for the upper bound notification and recovery times are also derived. Finally, we estimate that our system can recover from a fault in less than 0.5 ms for a 100 km ring length.

Density and Viscosity in Ternary d-Xylose + Ionic Liquid (1-Alkyl-3-methylimidazolium Bromide) + Water Solutions at 298.15 K

To probe the effect of ionic liquid structure on the thermophysical properties of aqueous d-xylose solutions, density and viscosity measurements were carried out at 298.15 K for ternary solutions comprising d-xylose and an ionic liquid {1-hexyl-3-methylimidazolium bromide ([HMIm]Br), 1-octyl-3-methylimidazolium bromide ([OMIm]Br), and 1-decyl-3-methylimidazoliume bromide ([DMIm]Br)} in aqueous medium. These data have been used to calculate some important thermophysical properties including standard partial molar volumes (Vϕ0), viscosity B-coefficients (using the Jones–Dole equation), and free energy of activation per mole of solvent (Δμ10≠) and solute (Δμ20≠) from Feakin’s transition state theory. It was observed that all the parameters increase with increasing both the concentration and the alkyl chain length of the imidazolium ring of the ionic liquids. These quantities have been utilized to rationalize structural interactions and the hydration behavior of d-xylose.

Excited States in Cycloparaphenylenes: Dependence of Optical Properties on Ring Length

Hoop-shaped conjugated molecules, cycloparaphenylenes (CPPs), are simple strings of benzene rings with para linkages that have an ideal quasi-one-dimensional structure without edges. Here, we report optical properties of [n]CPPs (n = 9, 12, 14, 15, 16) clarified by one- and two-photon excitation spectroscopy. We showed that in this system the lowest unoccupied molecular orbital (LUMO) state has the same symmetry as the highest occupied molecular orbital (HOMO) state, and determined the transition energy of the optically forbidden HOMO-LUMO gap. It is found that the ring-length dependence of the HOMO-LUMO transition energy is identical to that of the photoluminescence (PL) energy, and that phonon-assisted transition causes efficient PL.

Impact Characteristics Study on Electromagnet Magnetic Isolation Ring to Electromagnetic Force

This paper makes simulation analysis on an electromagnetic valve product based on ANSYS software by changing the angle, position, length and permeability of electromagnet magnetic isolation ring, and get different electromagnetic force curves. According to electromagnetic force curves, it can verify the importance of magnetic isolation ring’s existence. Comparing simulation results curve with measured electromagnetic force curve, it can find that Attenuation trend of two curves are consistent, which can prove the reliability of simulation by ANSYS software. This study makes a series of electromagnetic force simulation by changing the angle, relative position, and length of magnetic isolation ring. The results show that the influence of relative position’s change to electromagnetic force is more obvious than other factors. The conclusion can be taken as reference by electromagnetic valve designers. Furthermore, there exists important application value in this series of electromagnetic valve optimal design process.

Analytical Model of Magnetic Force for Axial Stack Permanent-Magnet Bearings

Based on magnetic field of plane point magnetic charge, virtual work principle, and superposition theorem, the magnetic force analytical model for axial stack permanent-magnet bearings (PMB) is established. The aim is to solve the problem of the magnetic force analytical model's lack of being convenient in engineering design calculation of axial stack PMB. The relationship between magnetic force and structure parameters of PMB is analyzed. ANSYS simulation is adopted to test the validity of the magnetic force analytical model. The results indicate that the magnetic force of axial stack PMB is proportional to the magnetic annular average perimeter and the square of residual magnetism induction density, and that the magnetic force increases with an increment in the magnetic annular radial width and magnetic annular number. In the case of similar geometric parameters, the magnetic force of the same direction magnetization axial stack PMB is minimum: when the number of stack magnetic ring is 4, the maximum magnetic force of reversal magnetization axial stack PMB is approximately 4 times as much as the maximum magnetic force of equi-directional magnetization axial stack PMB; when the axial offset is only half of the axial length of single magnetic ring, the axial magnetic force is the maximum. Accordingly, the maximum magnetic force of rotational magnetization axial stack PMB is roughly 1.5 times as much as the maximum magnetic force of reversal magnetization axial stack PMB. When the axial deflection is equal to the axial length of single magnetic ring, the axial magnetic force is the maximum.

Theoretical study of persistent current in a nanoring made of a band insulator

AbstractWe study theoretically persistent currents in rings made of band insulators with a fully occupied valence band and empty conduction band. We derive an expression for the persistent current in a one‐dimensional (1D) insulating ring with an arbitrary valence band ε(k). Setting for ε(k) the realistic (numerically calculated) valence bands, we estimate persistent currents in the nanorings made of real band insulators like GaAs, Ge, and InAs. Further, we express the persistent current in the insulating 1D ring through the Wannier functions of the constituting infinite 1D crystal. We find these Wannier functions analytically in the LCAO approximation. We obtain fully analytically the persistent current in the insulating ring and we apply the result to a 1D GaAs ring with conduction electrons subjected to a periodic potential emulating the insulating lattice. In general, persistent currents in rings made of band insulators decay with the ring length exponentially due to the exponential decay of the Wannier function tails. In spite of that, the currents of measurable size are found for a suitably chosen nanorings similar to those fabricated recently for coherent nanoelectronics. Finally, to provide insight, our major results are rederived from the so‐called ring Wannier functions.

Political Effect on Major Transport Elements of Budapest after the Transition

The aim of our article is to describe the connection between the Hungarian political environment and the development of the transport system of the Hungarian capital, Budapest, since the beginning of economic transition. The starting point of our research is the beginning of the transitions as from this period the political parties had the chance to make changes in the transport sector in order to build a liveable city. The authors have reviewed the urban transport programs of the parties, which they planned to realize in the case of winning the elections. The authors have dealt only with parties which were present in the Parliament during all parliamentary periods since 1990. The authors have investigated four parameters: length of express roads and the length of the M0 ring road as a parameter of economic growth and development, service levels (length of services, average age of vehicles, number of vehicles) of BKV (a monopoly responsible for urban transport in Budapest) and the length of cycle paths.