Development of X-ray phase CT with a hybrid configuration of Lau and Talbot-Lau interferometers.

X-ray phase computed tomography (CT) is used to observe the inside of light materials. In this paper, we report a new study to develop and test a laboratory assembled X-ray phase CT system that comprises an X-ray Lau interferometer, a rotating Mo anode X-ray tube, and a detector with high spatial resolution. The system has a high spatial resolution lower than 10 µm, which is evaluated by differentiating neighbouring carbon fibres in a polymer composite material. The density resolution is approximately 0.035 g/cm3, which enables to successfully distinguish the high-density polyethylene (HDPE, 0.93 g/cm3) from the ultra-low-density polyethylene (ULDPE, 0.88 g/cm3) in the sample. Moreover, the system can be switched to operate on another mode based on a Talbot-Lau interferometer that provides a wider field of view with a moderate spatial resolution (approximately 100 µm). By analyzing sample images of the biological, this study demonstrates the feasibility and advantages of using hybrid configuration of this X-ray phase CT system.

Superflexibility of ITO Electrodes via Submicron Patterning.

Indium tin oxide (ITO) is the premier choice for transparent conductive electrodes in optoelectronic devices despite its inherent brittleness. Here we report the fabrication of a grating-like structure that obviates ITO's mechanical limitations while retaining its resistivity and optical qualities. ITO nanopatterned films exhibited a resistivity <1.3 × 10-3 Ω cm, which surpassed all previously reported values for flexible ITO, with a normal transmission >90% across the whole visible spectrum range. We demonstrate the nanopatterned ITO retains extraordinary flexibility and durability on heat-sensitive substrates, accommodating cyclic bending to a curvature diameter of at least 3.2 mm for over 50 cycles of compressive and decompressive flexing without significant deterioration of its resistivity or optical properties. Moreover, 2-dimensional extrapolation shows that multiaxial bending is also feasible while maintaining mechanical flexibility, durability, and optical transparency.

Hemodynamic Response of the Supplementary Motor Area during Locomotor Tasks with Upright versus Horizontal Postures in Humans.

To understand cortical mechanisms related to truncal posture control during human locomotion, we investigated hemodynamic responses in the supplementary motor area (SMA) with quadrupedal and bipedal gaits using functional near-infrared spectroscopy in 10 healthy adults. The subjects performed three locomotor tasks where the degree of postural instability varied biomechanically, namely, hand-knee quadrupedal crawling (HKQuad task), upright quadrupedalism using bilateral Lofstrand crutches (UpQuad task), and typical upright bipedalism (UpBi task), on a treadmill. We measured the concentration of oxygenated hemoglobin (oxy-Hb) during the tasks. The oxy-Hb significantly decreased in the SMA during the HKQuad task, whereas it increased during the UpQuad task. No significant responses were observed during the UpBi task. Based on the degree of oxy-Hb responses, we ranked these locomotor tasks as UpQuad > UpBi > HKQuad. The order of the different tasks did not correspond with postural instability of the tasks. However, qualitative inspection of oxy-Hb time courses showed that oxy-Hb waveform patterns differed between upright posture tasks (peak-plateau-trough pattern for the UpQuad and UpBi tasks) and horizontal posture task (downhill pattern for the HKQuad task). Thus, the SMA may contribute to the control of truncal posture accompanying locomotor movements in humans.

Effect of Dual Therapy with Botulinum Toxin A Injection and Electromyography-controlled Functional Electrical Stimulation on Active Function in the Spastic Paretic Hand.

BACKGROUND: Many previous studies have demonstrated that botulinum toxin A (BTX-A) injections satisfactorily reduce spasticity. Nevertheless, BTX-A, with or without an adjuvant therapy, effectively improves the direct functional movement in few patients with spastic upper extremity paralysis. Therefore the present study aimed to determine the effectiveness of task-orientated therapy on spasticity and functional movement by using electromyography-triggered functional electrical stimulation (EMG-FES) after BTX-A injections. DESIGN: Open-label, prospective clinical trial Method: The subjects were 15 patients with spastic paresis (12 male, 3 female; age range, 17-74 years; 14 due to stroke, 1 due to spinal cord injury) who received BTX-A injections. Before the study was started, all subjects had undergone task-orientated therapy sessions with EMG-FES for 4 months. Despite all patients showing a various extent of improved upper extremity function, upper extremity function reached a plateau because of upper extremity spasticity. After BTX-A injection, all patients underwent task-orientated therapy sessions with EMG-FES for 4 months. The outcomes were assessed with the modified Ashworth scale, the simple test for evaluating hand function, box and block test, grip and release test, finger individual movement test, and grip strength. Assessments were performed at baseline and 10 days and 4 months after BTX-A injection. RESULTS: The median modified Ashworth scale score decreased from 2 at baseline to 1 at 10 days and 4 months after BTX-A injection. The finger individual movement test score increased slightly at 10 days (p=0.29) and further increased at 4 months (p<0.05). The simple test for evaluating hand function, grip and release test, box and block test, and grip strength decreased after 10 days (p<0.05, p=0.26, p<0.01, and p<0.01, respectively) but increased after 4 months (p<0.01, p<0.05, p<0.01, and p=0.18, respectively). CONCLUSION: Task-orientated therapy with EMG-FES after BTX-A injection effectively reduced spasticity and improved upper limb motor function. Our results also suggest that spasticity occurs as a compensation for the force of the affected muscles and leads to misuse movements and ostensible dexterity in many patients. In addition, we hypothesize that BTX-A injection initializes the abnormal adapted movement pattern and that more active hand movements with facilitation of the paretic muscles when using EMG-FES induce an efficient muscle reeducation of the inherent physiological movement pattern that ultimately could prove useful in the activities of daily living.

Evaluation of X-ray doses and their corresponding biological effects on experimental animals in cone-beam micro-CT scans (R-mCT2).

Studies show that the radiation dose received during a micro-CT examination may have adverse effects on living subjects. However, the correlations between the biological effects and the radiation doses have never been thoroughly evaluated in the majority of cases. In this study, we evaluated the biological radiation effects of measured radiation doses in ICR mice using cone-beam micro-CT scans. Long-term in vivo whole-body micro-CT scans of ICR mice were performed for a duration of 4 weeks. Although a scanning frequency of three scans per week is higher than that necessary for conventional studies, this study represents particular cases where the subjects may undergo an extreme number of examinations. The average X-ray dose of a CT scan measures 16.19 mGy at the center of a phantom and 16.24 mGy at an offset position of 7.5 mm from the center of the phantom. The total average dose at the center of the phantom during the 4-week scanning period was 194.3 mGy. No significant radiation effects were observed in the weight gain curves, organ weights, blood analyses, litter sizes, reared offspring sizes, and the histopathologic results. Therefore, it is unlikely that the measured doses for the CT scans caused any radiation damage in the mice.

Modeling photovoltaic performance in periodic patterned colloidal quantum dot solar cells.

Colloidal quantum dot (CQD) solar cells have attracted tremendous attention mostly due to their wide absorption spectrum window and potentially low processability cost. The ultimate efficiency of CQD solar cells is highly limited by their high trap state density. Here we show that the overall device power conversion efficiency could be improved by employing photonic structures that enhance both charge generation and collection efficiencies. By employing a two-dimensional numerical model, we have calculated the characteristics of patterned CQD solar cells based of a simple grating structure. Our calculation predicts a power conversion efficiency as high as 11.2%, with a short circuit current density of 35.2 mA/cm2, a value nearly 1.5 times larger than the conventional flat design, showing the great potential value of patterned quantum dot solar cells.

Enhancing light absorption within the carrier transport length in quantum junction solar cells.

Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31 mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells.

Brain plasticity and rehabilitation in stroke patients.

In recent years, our understanding of motor learning, neuroplasticity and functional recovery after the occurrence of brain lesion has grown significantly. Novel findings in basic neuroscience have provided an impetus for research in motor rehabilitation. The brain reveals a spectrum of intrinsic capacities to react as a highly dynamic system which can change the properties of its neural circuits. This brain plasticity can lead to an extreme degree of spontaneous recovery and rehabilitative training may modify and boost the neuronal plasticity processes. Animal studies have extended these findings, providing insight into a broad range of underlying molecular and physiological events. Neuroimaging studies in human patients have provided observations at the systems level that often parallel findings in animals. In general, the best recoveries are associated with the greatest return toward the normal state of brain functional organization. Reorganization of surviving central nervous system elements supports behavioral recovery, for example, through changes in interhemispheric lateralization, activity of association cortices linked to injured zones, and organization of cortical representational maps. Evidence from animal models suggests that both motor learning and cortical stimulation alter intracortical inhibitory circuits and can facilitate long-term potentiation and cortical remodeling. Current researches on the physiology and use of cortical stimulation animal models and in humans with stroke related hemiplegia are reviewed in this article. In particular, electromyography (EMG) -controlled electrical muscle stimulation improves the motor function of the hemiparetic arm and hand. A multi-channel near-infrared spectroscopy (NIRS) studies in which the hemoglobin levels in the brain were non-invasively and dynamically measured during functional activity found that the cerebral blood flow in the injured sensory-motor cortex area is greatest during an EMG-controlled FES session. Only a few idea is, however, known for the optimal timing of the different processes and therapeutic interventions and for their interactions in detail. Finding optimal rehabilitation paradigms requires an optimal organization of the internal processes of neural plasticity and the therapeutic interventions in accordance with defined plastic time windows. In this review the mechanisms of spontaneous plasticity after stroke and experimental interventions to enhance plasticity are summarized, with an emphasis on functional electrical stimulation therapy.

Controlled seeding of laser deposited Ta:TiO2 nanobrushes and their performance as photoanode for dye sensitized solar cells.

Hexagonal patterned indium tin oxide (ITO) with a height of 1.5 µm was fabricated on fluorinated SnO2 (FTO) substrate via nanoimprint lithography and pulsed laser deposition (PLD). Tantalum doped TiO2 was deposited on the patterned substrate by PLD. The film of Ta:TiO2 grew vertically and separately on the patterned ITO and formed a brush-like structure. Dye-sensitized solar cells with the Ta:TiO2 film deposited on the patterned substrate as well as flat FTO substrate for comparison were fabricated and tested. The device with the patterned substrate showed a 25% increase in short circuit current (Jsc) compared to the one with flat FTO substrate. Optical and photoelectrochemical characterization techniques were performed to investigate the improvement. The increase of Jsc was attributed to the enhancements of light absorption in the 600-750 nm range and collection of excited electrons by the brush-like structure and the patterned ITO, respectively.

Modulation of cortical vestibular processing by somatosensory inputs in the posterior insula.

PRIMARY OBJECTIVE: To study the mechanism of somatosensory-vestibular interactions, this study examined the effects of somatosensory inputs on body sway induced by galvanic vestibular stimulation (GVS) in healthy participants and persons with brain injury in the posterior insula, a region constituting a part of the parietoinsular vestibular cortex. RESEARCH DESIGN: This study adopted an experimental, controlled, repeated measures design. METHODS AND PROCEDURES: Participants were 11 healthy individuals, two persons with unilateral posterior insular injury and two age-matched controls. Bipolar GVS was applied to the mastoid processes while participants were sitting with their eyes closed, either lightly touching a stable surface with their index finger or not touching the surface with their index finger. MAIN OUTCOMES AND RESULTS: In healthy participants, tilting was greater with right hemispheric stimulation than with left hemispheric stimulation. Moreover, with right hemispheric stimulation, tilting was greater with a right finger touch than with no touch. The person with right-brain injury showed tilting induced by GVS; however, finger touch had no modulatory effect. In contrast, finger touch enhanced tilting in the person with left-brain injury. CONCLUSIONS: These preliminary results are discussed in light of a hypothesis of right hemispheric dominance of somatosensory-vestibular interactions in the posterior insula.

The effects of electromyography-controlled functional electrical stimulation on upper extremity function and cortical perfusion in stroke patients.

OBJECTIVE: The relation was investigated between hemiparetic arm function improvement and brain cortical perfusion (BCP) change during voluntary muscle contraction (VOL), EMG-controlled FES (EMG-FES) and simple electrical muscle stimulation (ES) before and after EMG-FES therapy in chronic stroke patients. METHODS: Sixteen chronic stroke patients with moderate residual hemiparesis underwent 5 months of task-orientated EMG-FES therapy of the paretic arm once or twice a week. Before and after treatment, arm function was clinically evaluated and BCP during VOL, ES and EMG-FES were assessed using multi-channel near-infrared spectroscopy. RESULTS: BCP in the ipsilesional sensory-motor cortex (SMC) was greater during EMG-FES than during VOL or ES; therefore, EMG-FES caused a shift in the dominant BCP from the contralesional to ipsilesional SMC. After EMG-FES therapy, arm function improved in most patients, with some individual variability, and there was significant improvement in Fugl-Meyer (FM) score and maximal grip strength (GS). Clinical improvement was accompanied by an increase in ipsilesional SMC activation during VOL and EMG-FES condition. CONCLUSION: The EMG-FES may have more influence on ipsilesional BCP than VOL or ES alone. SIGNIFICANCE: The sensory motor integration during EMG-FES therapy might facilitate BCP of the ipsilesional SMC and result in functional improvement of hemiparetic upper extremity.

Hypofrontal activity during word retrieval in older adults: a near-infrared spectroscopy study.

The supplementary motor area (SMA) has been regarded as a third speech area. The SMA is anatomically classified into two regions, pre-SMA and SMA proper, but the functional specialization of speech production between the two regions remains unknown. Although word retrieval difficulties were often observed in older adults, there was no report as to whether the SMA would be involved in the retrieval difficulties. We focused on the SMA as a function of word production and then used near-infrared spectroscopy (NIRS) with the verbal fluency task (VFT) to explore the possible mechanism underlying the retrieval difficulties related to aging. Based on the anatomical differences within the SMA, we relied on region-of-interest (ROI) analysis to compare the brain activation patterns in the SMA during VFT between 11 healthy elder and 11 younger subjects in the situation where both groups show comparable task performance. Notably, the anterior VFT-related SMA response was more robust in the younger than in the elder group. Furthermore, anterior SMA responses in the elder group may only have a positive correlation with the VFT performance. The findings imply that anterior SMA hypoactivity in elders may cause word retrieval difficulties, while bilateral prefrontal cortices, having close connection with the pre-SMA, may contribute to the compensatory process that enables equivalent performance of the elder group with the younger one.

Increasing photocurrents in dye sensitized solar cells with tantalum-doped titanium oxide photoanodes obtained by laser ablation.

Laser ablation is employed to produce vertically aligned nanostructured films of undoped and tantalum-doped TiO(2) nanoparticles. Dye-sensitized solar cells using the two different materials are compared. Tantalum-doped TiO(2) photoanode show 65% increase in photocurrents and around 39% improvement in overall cell efficiency compared to undoped TiO(2). Electrochemical impedance spectroscopy, Mott-Schottky analysis and open circuit voltage decay is used to investigate the cause of this improved performance. The enhanced performance is attributed to a combination of increased electron concentration in the semiconductor and a reduced electron recombination rate.

Interface engineering by piezoelectric potential in ZnO-based photoelectrochemical anode.

Through a process of photoelectrochemical (PEC) water splitting, we demonstrated an effective strategy for engineering the barrier height of a heterogeneous semiconductor interface by piezoelectric polarization, known as the piezotronic effect. A consistent enhancement or reduction of photocurrent was observed when tensile or compressive strains were applied to the ZnO anode, respectively. The photocurrent variation is attributed to a changed barrier height at the ZnO/ITO interface, which is a result of the remnant piezoelectric potential across the interface due to a nonideal free charge distribution in the ITO electrode. In our system, ∼1.5 mV barrier height change per 0.1% applied strain was identified, and 0.21% tensile strain yielded a ∼10% improvement of the maximum PEC efficiency. The remnant piezopotential is dictated by the screening length of the materials in contact with piezoelectric component. The difference between this time-independent remnant piezopotential effect and time-dependent piezoelectric effect is also studied in details.

Three-dimensional high-density hierarchical nanowire architecture for high-performance photoelectrochemical electrodes.

Three-dimensional (3D) nanowire (NW) networks are promising for designing high-performance photoelectrochemical (PEC) electrodes owing to their long optical path for efficient light absorption, high-quality one-dimensional conducting channels for rapid electron-hole separation and charge transportation, as well as high surface areas for fast interfacial charge transfer and electrochemical reactions. By growing titanium dioxide (TiO(2)) nanorods (NRs) uniformly on dense Si NW array backbones, we demonstrated a novel three-dimensional high-density heterogeneous NW architecture that could enhance photoelectrochemical efficiency. A 3D NW architecture consisting of 20 µm long wet-etched Si NWs and dense TiO(2) NRs yielded a photoelectrochemical efficiency of 2.1%, which is three times higher than that of TiO(2) film-Si NWs having a core-shell structure. This result suggests that the 3D NW architecture is superior to straight NW arrays for PEC electrode design. The efficiency could be further improved by optimizing the number of overcoating cycles and the length/density of NW backbones. By implementing these 3D NW networks into electrode design, one may be able to advantageously impact PEC and photovoltaic device performance.

[Neuro-rehabilitation for neurological disease].

Our understanding of motor learning, neuro-plasticity and functional recovery after the occurrence of brain lesion has grown significantly. New findings in basic neuroscience provided stimuli for research in motor rehabilitation. Electrical stimulation can be applied in a variety of ways to the neurological impairment. Especially, electromyography (EMG) initiated electrical muscle stimulation improves motor dysfunction of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than non-triggered electrical stimulation in facilitating upper extremity motor recovery. Power-assisted FES induces greater muscle contraction by electrical stimulation in proportion to the voluntary integrated EMG signal picked up. Daily power-assisted FES home program therapy with the novel equipment has been able to improve wrist, finger extension and shoulder flexion effectively. Combined modulation of voluntary movement, proprioceptional sensory feedback and electrical stimulation might play an important role to facilitate impaired sensory-motor integration in power-assisted FES therapy. It is recognized that increased cerebral blood flow in the sensory-motor cortex area on the injured side during power-assisted FES session compared to simple active movement or simple electrical stimulation in a multi-channels Near-infrared spectroscopy (NIRS) study to non-invasively and dynamically measure hemoglobin levels in the brain during functional activity.

[Novel functional electrical stimulation for neurorehabilitation].

Our understanding of motor learning, neuroplasticity, and functional recovery after the occurrence of brain lesions has increased considerably. New findings in basic neuroscience have provided an impetus for research in motor rehabilitation. Several prospective studies have shown that repeated motor practice and motor activity in a real world environment have a favorable effect on motor recovery in stroke patients. Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following a stroke. In particular, electromyography (EMG)-triggered electrical muscle stimulation improves the motor function of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than non-triggered electrical stimulation in facilitating upper extremity motor recovery after stroke. Power-assisted functional electrical stimulation (FES) induces greater muscle contraction by electrical stimulation that is in proportion to voluntary integrated EMG signals. Daily power-assisted FES home-program therapy with novel equipment has been shown to effectively improve wrist, finger extension, and shoulder flexion. Combined modulation of voluntary movement, proprioceptive sensory feedback, and electrical stimulation might play an important role in improving impaired sensory-motor integration by power-assisted FES therapy. A multi-channel near-infrared spectroscopy (NIRS) studies in which the hemoglobin levels in the brain were non-invasively and dynamically measured during functional activity found that the cerebral blood flow in the injured sensory-motor cortex area is greater during a power-assisted FES session than during simple active movement or simple electrical stimulation. A novel power-assisted FES sleeve (Cyberhand) has been developed for the rehabilitation of hemiplegic upper extremities.

Deep venous thrombosis in stroke patients during rehabilitation phase.

PURPOSE: The purpose of this study was to examine the incidence, factors, and effects of antiplatelet and anticoagulant agents on sub-acute and chronic ischemic stroke patients during the rehabilitation phase for rates of deep venous thrombosis (DVT) from the perspective for rehabilitation medicine. METHODS: In this study of 272 patients undergoing rehabilitation for completed cerebral infarction, multiple circumference measurements of calf and thigh along with presence or absence of symptoms (congestion, swelling, skin redness, warmth, pain, pigmentation, fever and/or Homan sign or Luck's sign) documented in the physical examination were recorded in all patients. Patients with these symptoms suggestive of DVT were included for D-dimer assay and venous duplex ultrasonography to confirm presence of DVT. RESULTS: DVT was documented in 24 patients (8.8%), most of whom displayed distal DVT on the hemiparetic side. A significant association was seen between occurrence of DVT and more severe lower limb paresis, manifesting as gait disturbance, severe calf muscle spasticity, use of ankle-foot orthosis (AFO). A significant increase in development of DVT was associated with severe spasticity in hemiparetic calf muscles (odds ratio (OR) 28.2; 95% confidence interval (CI), 6.9-113.5). Cilostazol seemed to be the only effective antiplatelet drug for preventing DVT in cerebral infarction patients. CONCLUSION: Incidence of DVT in the rehabilitation phase following stroke was not low, which was predominant as distal DVT on the hemiparetic side. Lower limb paresis, gait disturbance, calf muscle spasticity and use of AFO contributed to occurrence of DVT. It is likely that micro-injuries in the venous endothelium due to spasticity and AFO might cause DVT. Cilostazol seems effective for protecting against venous endothelial damage following DVT.

Neurorehabilitation with new functional electrical stimulation for hemiparetic upper extremity in stroke patients.

In recent years, our understanding of motor learning, neuroplasticity, and functional recovery after the occurrence of brain lesion has grown significantly. New findings in basic neuroscience have stimulated research in motor rehabilitation. Repeated motor practice and motor activity in a real-world environment have been identified in several prospective studies as favorable for motor recovery in stroke patients. Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following stroke. In this paper, an overview of current research into clinical and therapeutic applications of functional electrical stimulation (FES) is presented. In particular, electromyography (EMG)-initiated electrical muscle stimulation--but not electrical muscle stimulation alone--improves the motor function of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than untriggered electrical stimulation in facilitating upper extremity motor recovery following stroke. Power-assisted FES induces greater muscle contraction by electrical stimulation in proportion to the voluntary integrated EMG signal picked up, which is regulated by a closed-loop control system. Power-assisted FES and motor point block for antagonist muscles have been applied with good results as a new hybrid FES therapy in an outpatient rehabilitation clinic for patients with stroke. Furthermore, a daily home program therapy with power-assisted FES using new equipment has been able to effectively improve wrist and finger extension and shoulder flexion. Proprioceptive sensory feedback might play an important role in power-assisted FES therapy. Although many physiotherapeutic modalities have been established, conclusive proof of their benefit and physiological models of their effects on neuronal structures and processes are still missing. A multichannel near-infrared spectroscopy study to noninvasively and dynamically measure hemoglobin levels in the brain during functional activity has shown that cerebral blood flow in the sensory-motor cortex on the injured side is higher during a power-assisted FES session than during simple active movement or simple electrical stimulation. Nevertheless, evidence-based strategies for motor rehabilitation are more easily available, particularly for patients with hemiparesis.