Photocatalytic Activity of Hierarchically Structured TiO 2

Hierarchically structured TiO2 photocatalyst films were synthesized using low-pressure metal-organic chemical vapor deposition (LPMOCVD) method to examine their photocatalytic activity. The thickness of the TiO2 films increased proportionally with increasing deposition time. The TiO2 film synthesized at 773 K showed a hierarchical structure composed of vertically grown laminar (112)-oriented anatase crystals. With increasing deposition time, the grain became larger and the morphology became sharper. In the initial CVD stage, small particular crystals were formed, above which sequential growth of layers of columnars with increasing size took place, forming hierarchical structure. The hierarchically structured TiO2 film exhibited much higher photocatalytic activity than unhierarchically structured TiO2 film. The photocatalytic activity increased with increasing film thickness

Strong Bathochromic Shift of Conjugated Polymer Nanowires Assembled with a Liquid Crystalline Alkyl Benzoic Acid via a Film Dispersion Process

We present aqueous dispersions of conjugated polymer nanowires (CPNWs) with improved light absorption properties aimed at aqueous-based applications. We assembled films of a donor???acceptor-type conjugated polymer and liquid crystalline 4-n-octylbenzoic acid by removing a cosolvent of their mixture solutions, followed by annealing of the films, and then formed aqueous-dispersed CPNWs with an aspect ratio >1000 by dispersing the films under ultrasonication at a basic pH. X-ray and spectroscopy studies showed that the polymer and liquid crystal molecules form independent domains in film assemblies and highly organized layer structures in CPNWs. Our ordered molecular assemblies in films and aqueous dispersions of CPNWs open up a new route to fabricate nanowires of low-band-gap linear conjugated polymers with the absorption maximum at 794 nm remarkably red-shifted from 666 nm of CPNWs prepared by an emulsion process. Our results suggest the presence of semicrystalline polymorphs ??1 and ??2 phases in CPNWs due to long-range ??????? stacking of conjugated backbones in compactly organized lamellar structures. The resulting delocalization with a reduced energy bang gap should be beneficial for enhancing charge transfer and energy-conversion efficiencies in aqueous-based applications such as photocatalysis

Giant thermal hysteresis in Verwey transition of single domain Fe3O4 nanoparticles

Most interesting phenomena of condensed matter physics originate from interactions among different degrees of freedom, making it a very intriguing yet challenging question how certain ground states emerge from only a limited number of atoms in assembly. This is especially the case for strongly correlated electron systems with overwhelming complexity. The Verwey transition of Fe3O4 is a classic example of this category, of which the origin is still elusive 80 years after the first report. Here we report, for the first time, that the Verwey transition of Fe3O4 nanoparticles exhibits size-dependent thermal hysteresis in magnetization, 57Fe NMR, and XRD measurements. The hysteresis width passes a maximum of 11 K when the size is 120 nm while dropping to only 1 K for the bulk sample. This behavior is very similar to that of magnetic coercivity and the critical sizes of the hysteresis and the magnetic single domain are identical. We interpret it as a manifestation of charge ordering and spin ordering correlation in a single domain. This work paves a new way of undertaking researches in the vibrant field of strongly correlated electron physics combined with nanoscience.Comment: 13 pages, 4 figure

Review of Interventional Therapies for Refractory Pediatric Migraine.

This is a review of the latest and seminal evidence in pediatric migraine. It covers the etiology and pathophysiology known today, and then will review treatment options, efficacy and safety, quality of data and indications. Though migraine is usually regarded as an infliction in adults, it is not uncommon in the pediatric population and affects up to 8% of children. Children may experience migraine differently than adults, and present not only with headache but also frequent gastrointestinal symptoms. They are frequently shorter in duration than in adults. Traditional migraine treatment in adults is less effective in children. In this population, adjunct therapies - such as interventional techniques - should be considered when traditional treatment fails, including Botulinum Toxin A (BTA) injections, peripheral nerve and ganglion blocks. BTA injections are FDA approved for migraine prophylaxis in adults, but currently not in children; however, recent evidence shows efficacy and safety in pediatric migraine management. Nerve blocks stop nociceptive afferent fibers through injection of local anesthetics, and it may be associated with the local injection of corticosteroids. Although more common in adults, recent data suggests they are safe and effective in children and adolescents. Blocking the sphenopalatine ganglion can be achieved through nasal approach, and achieves a similar action by blocking the entire ganglion. Interventional techniques may provide a key component in the alleviation of this otherwise debilitating chronic migraine pain. Though most studies have been performed in adults, new studies provide encouraging results for treatment in children

Vibrotactile Speech Communication: Perceptual Studies with a Phonemic-Based Display

Tactile communication systems provide an alternative channel of communication for people with all levels of sensory capabilities and can help those with sensory impairments to receive information through another sensory modality. Recently, a TActile Phonemic Sleeve (TAPS) has been developed with the objective of enabling people to “hear through the skin.” This thesis presents three studies that evaluate the feasibility of the TAPS system for phoneme and word acquisition and for two-way tactual communication. The TAPS system is based on a phonemic-based coding scheme that uses an array of 24 (6-by-4) tactors to convey haptic stimuli on the forearm. In Study 1, an effective mechanism for learning phonemes and words with TAPS based on the theory of memory consolidation was explored. Four naive participants learned to recognize 51 words made up of 10 phonemes within 60 min of experimental time. A fifth naive participant demonstrated the ability to learn all 39 phonemes of the English language as haptic codes after a total of 80 min with a phoneme identification score of 93.8%. We found that with the distinctive set of haptic symbols that had been developed prior to this thesis, participants were able to learn phonemes and words in a short amount of time. We also validated the memory consolidation theory by showing an improvement in phoneme recognition score when the fifth naive participant was re-assessed the day after he had learned the phonemes. In Study 2, we evaluated the learning performance of longer (four-phoneme) words. A total of three experienced participants spent 20 min per day for 3 days to review 39 phonemes and 500 words (with most of the words containing two or three phonemes) that they had learned in an earlier study. They then spent 10 more days to practice and test with a word list consisting of 100 four-phoneme words (List #1). A generalization study was conducted by testing the same participants with a different set of 100 four-phoneme words (List #2) during the last 2 days of the experiment. After the 15-day experimental period, the average word percent-correct (PC) scores of the three participants for List #1 and List #2 were 80.2% and 72.3%, respectively. Both results were well above the corresponding chance levels (1% for the closed set of words in List #1 and near 0 for the open set of words in List #2) which demonstrated that the participants were able to learn longer words with the TAPS system within a reasonable amount of time. In Study 3, the feasibility of TAPS for tactile communication of spontaneous speech was evaluated. Two of the three experienced participants from Study 2 sent text messages to each other through two identical TAPS systems with an open set of words. The average percent-correct (PC) scores for the two participants for messages (PCmsg) and words (PCword) were 73.4% and 81.7%, respectively. These results are impressive considering that the participants had to recognize words and phrases using an open vocabulary. Overall, the three studies demonstrate that the users of the TAPS system can successively receive phonemes, isolated words up to 4 phonemes in length, phrases, and sentences in a two-way exchange that simulates daily communication scenarios. Future work will explore the design of additional haptic symbols for conveying punctuation marks and investigate the efficacy of the TAPS system in helping people with sensory impairments to communicate via the sense of touch

Consistent Partial Least Squares Path Modeling via Regularization

Partial least squares (PLS) path modeling is a component-based structural equation modeling that has been adopted in social and psychological research due to its data-analytic capability and flexibility. A recent methodological advance is consistent PLS (PLSc), designed to produce consistent estimates of path coefficients in structural models involving common factors. In practice, however, PLSc may frequently encounter multicollinearity in part because it takes a strategy of estimating path coefficients based on consistent correlations among independent latent variables. PLSc has yet no remedy for this multicollinearity problem, which can cause loss of statistical power and accuracy in parameter estimation. Thus, a ridge type of regularization is incorporated into PLSc, creating a new technique called regularized PLSc. A comprehensive simulation study is conducted to evaluate the performance of regularized PLSc as compared to its non-regularized counterpart in terms of power and accuracy. The results show that our regularized PLSc is recommended for use when serious multicollinearity is present

A Multi-Agent Driving-Simulation Approach for Characterizing Hazardous Vehicle Interactions between Autonomous Vehicles and Manual Vehicles

The advent of autonomous vehicles (AVs) in the traffic stream is expected to innovatively prevent crashes resulting from human errors in manually driven vehicles (MVs). However, substantial safety benefits due to AVs are not achievable quickly because the mixed-traffic conditions in which AVs and MVs coexist in the current road infrastructure will continue for a considerably long period of time. The purpose of this study is to develop a methodology to evaluate the driving safety of mixed car-following situations between AVs and MVs on freeways based on a multi-agent driving-simulation (MADS) technique. Evaluation results were used to answer the question ‘What road condition would make the mixed car-following situations hazardous?’ Three safety indicators, including the acceleration noise, the standard deviation of the lane position, and the headway, were used to characterize the maneuvering behavior of the mixed car-following pairs in terms of driving safety. It was found that the inter-vehicle safety of mixed pairs was poor when they drove on a road section with a horizontal curve length of 1000 m and downhill slope of 1% or 3%. A set of road sections were identified, using the proposed evaluation method, as hazardous conditions for mixed car-following pairs consisting of AVs and MVs. The outcome of this study will be useful for supporting the establishment of safer road environments and developing novel V2X-based trafficsafetyinformation content that enables the enhancement of mixed-traffic safety