Luming Li

Carbon Nanotube Yarns for Deep Brain Stimulation Electrode

A new form of deep brain stimulation (DBS) electrode was proposed that was made of carbon nanotube yarns (CNTYs). Electrode interface properties were examined using cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The CNTY electrode interface exhibited large charge storage capacity (CSC) of 12.3 mC/cm2 which increased to 98.6 mC/cm2 after acid treatment, compared with 5.0 mC/cm2 of Pt-Ir. Impedance spectrum of both untreated and treated CNTY electrodes showed that finite diffusion process occurred at the interface due to their porous structure and charge was delivered through capacitive mechanism. To evaluate stability electrical stimulus was exerted for up to 72 h and CV and EIS results of CNTY electrodes revealed little alteration. Therefore CNTY could make a good electrode material for DBS.

Membrane stretch and cytoplasmic Ca2+ independently modulate stretch-activated BK channel activity

Large conductance Ca(2+)-activated K(+) (BK) channels are responsible for changes in chemical and physical signals such as Ca(2+), Mg(2+) and membrane potentials. Previously, we reported that a BK channel cloned from chick heart (SAKCaC) is activated by membrane stretch. Molecular cloning and subsequent functional characterization of SAKCaC have shown that both the membrane stretch and intracellular Ca(2+) signal allosterically regulate the channel activity via the linker of the gating ring complex. Here we investigate how these two gating principles interact with each other. We found that stretch force activated SAKCaC in the absence of cytoplasmic Ca(2+). Lack of Ca(2+) bowl (a calcium binding motif) in SAKCaC diminished the Ca(2+)-dependent activation, but the mechanosensitivity of channel was intact. We also found that the abrogation of STREX (a proposed mechanosensing apparatus) in SAKCaC abolished the mechanosensitivity without altering the Ca(2+) sensitivity of channels. These observations indicate that membrane stretch and intracellular Ca(2+) could independently modulate SAKCaC activity.

Fabrication of aligned side-by-side TiO 2 /SnO 2 nanofibers via dual-opposite-spinneret electrospinning

Well-aligned and uniform side-by-side bicomponent fibers have been produced via dual-opposite-spinneret electrospinning. Side-by-side TiO2/SnO2 nanofibers were obtained after calcining as-spun fibers. The thermal degradation of the electrospun fibers was evaluated using combined thermogravimetry and differential thermal analysis (TG-DTA), and the crystal structure of calcined nanofibers was investigated by X-ray diffraction (XRD). The fabricated TiO2/SnO2 nanofibers expose both TiO2 mainly consisting of anatase phase and rutile-type SnO2 to the surface, which is appropriate for photocatalytic materials.

A Novel Uni-Acupoint Electroacupuncture Stimulation Method for Pain Relief

Electroacupuncture stimulation (EAS) has been demonstrated effective for pain relief and treating other various diseases. However, the conventional way of EAS, the bi-acupoint method, is not suitable for basis study of acupoint specificity. Moreover, its operations are inconvenient and difficult to be persevered, especially for long-term, continuous and even imperative treatments. These disadvantages motivate designs of new EAS methods. We present a novel uni-acupoint electrical stimulation method, which is applied at a single acupoint and quite meets the needs of basis study and simpler clinical application. Its pain relief effect has been evaluated by animal tests of Wistar rats. During the experiments, rats were given 30 min 2/100 Hz uni- and bi-acupoint EAS and their nociceptive thresholds before and after EAS were attained by hot-plate test. The analgesic effect was defined as the change of nociceptive threshold and used to evaluate the effectiveness of uni-acupoint EAS for pain relief. The hot-plate test results indicated that analgesic effect of uni-acupoint group was significantly higher than that of the control group and there was no significant difference of analgesic effects between uni- and bi-acupoint EAS. The results suggested that uni-acupoint method was an effective EAS method and had comparable pain relief effect with bi-acupoint method.

An approach to generate software test data for a specific path automatically with genetic algorithm

We focus on software reliability with testing coverage, which will grow with increment of the coverage. We expect to improve quality of software testing with it automated. An approach of generating test data for a specific single path is presented in this paper, different from the predicate distance applied by most test data generators based on genetic algorithms. A similarity between the target path and execution path with sub path overlapped is designed as fitness value to evaluate the individuals of a population and drive GA to search the appropriate solutions. Several experiments are taken to examine the effectiveness of the designed fitness function, which evaluate performance of the function with the convergence ability and consumed time. Results show that the function performs well compared with other two typical fitness functions for specific paths.

Simulative and experimental research on wireless power transmission technique in implantable medical device

As the development of implantable biomedical devices, the rechargeable battery is applied to improve the life of implantable devices. Inductive transcutaneous power transfer, as a suitable way of charging the implantable rechargeable batteries, is widely used. During charging period, there are several stages based on the charging rule and the load resistance is varying simultaneously. In this paper, a model of inductive transcutaneous power transfer is set up with a compensative capacitor for primary coil in series and another compensative capacitor for secondary coil in parallel to descript the relationship in coupling coefficient, load resistance and conversion efficiency. Simulations were done and experiments were carried out to verify the model, and some suggestions on wireless power transfer design are given.

Variable frequency stimulation of subthalamic nucleus for freezing of gait in Parkinson’s disease

High frequency stimulation (HFS) of the subthalamic nucleus (STN) provides consistent, long-term improvement of the cardinal signs of Parkinsons disease (PD), such as bradykinesia, tremor and rigidity. Freezing of gait (FOG) responds poorly to HFS and deteriorates over time, but this can be alleviated by using relatively low frequency stimulation (LFS) [1]. There are two major concerns when applying LFS in clinical practice, the first being the duration of clinical benefit. Evidence indicates that LFS-STN can improve axial signs in some but not all PD patients, but most of them experienced loss of efficacy in the short term. Then patients are left with little improvement or increasing tremor, rigidity and bradykinesia, which consists of the three main signs of PD. Thus even if axial problems can be ameliorated by LFS in the long term, patients might find deterioration of motor symptoms difficult to tolerate. Strategies to bypass this tolerance phenomenon to LFS are needed. Here, we describe a patient with FOG who received variable frequency stimulation (VFS) where the stimulation frequency was set to alternate between high and low frequencies. In August 2012 after signing informed consent, a 66-year-old man was implanted with Deep Brain Stimulation systems [2] (PINS Medical). STN was chosen for the target. He developed rigidity in his limbs in the middle of 2007 and was diagnosed with PD in September of that year. Over time, his levodopa dose was increased from 250 mg to 1000 mg per day and 0.375 mg pramipexole was added. The levodopa equivalent dosage was decreased to 750 mg/ day one month after implantation and UPDRS score decreased from 57 to 21. Six months later he developed FOG. The parameters of active contacts, amplitude and frequency were changed, but had no effect on the gait. Variable frequency stimulation was then applied with a remarkable improvement in the FOG observed with little deterioration of the limb rigidity. Parameters were 2.7 V, 60 us, 60 Hz & 130 Hz (60 Hz for 20 s and 130 Hz for 30 s per cycle) to the right side and 1.7 V, 60 us, 60 Hz & 130 Hz (60 Hz for 20 s and 130 Hz for 30 s per cycle) to the left side. A Timed go (TUG) test was conducted and videoed to show the ment in the FOG (Table 1). The patient was followed-up by telephone after 4 months of VFS, and the benefit was still remarkable compared with traditional HFS, in spite of some deterioration. Supplementary data related to this article can be found online at http://dx.doi.org/10.1016/j.parkreldis.2015.10.002.

Potential Protective Effects of Chronic Anterior Thalamic Nucleus Stimulation on Hippocampal Neurons in Epileptic Monkeys

BACKGROUND Stimulation of the anterior nucleus of the thalamus (ANT) is effective in seizure reduction, but the mechanisms underlying the beneficial effects of ANT stimulation are unclear. OBJECTIVE To assess the beneficial effects of ANT stimulation on hippocampal neurons of epileptic monkeys. METHODS Chronic ANT stimulation was applied to kainic acid-induced epileptic monkeys. Behavioral seizures were continuously monitored. Immunohistochemical staining and western blot assays were performed to assess the hippocampal injury and the effects of ANT stimulation. RESULTS The frequency of seizures was 42.8% lower in the stimulation group compared with the sham-stimulation group. Immunohistochemical staining and western blot analyses indicated that neuronal loss and apoptosis were less severe and that neurofilament synthesis was enhanced in the stimulation monkeys compared with the sham-stimulation group. These data showed that the hippocampal injury was less severe in monkeys in the stimulation group than in those in the sham-stimulation group. CONCLUSIONS Our data suggest that chronic ANT stimulation may exert protective effects on hippocampal neurons and boost the regeneration of neuronal fibers. These effects may be closely related to the mechanisms of ANT stimulation in epilepsy treatment.

Magnetic signals of stress concentration detected in different magnetic environment

Stress concentration will generate a weak field leakage on the surface of ferromagnetic materials in the geomagnetic field because of the magneto-mechanical effect. Therefore, stress concentration can be evaluated by detecting the magnetic field on the surface of metal parts. This method has become an interesting focus to NDT researchers for its high sensitivity of magnetic field and no need of artificial magnetisation. However, this method also depends on the environmental magnetic field during detection. Although the stress status is the same, the testing results can be different because of the magnetic environment. With experiments in which a magnetic abnormality is generated by stress concentration in a nearly zero magnetic field but detected in another level of environmental magnetic field, the relationship between magnetic signals of stress concentration and the magnetic environment is investigated in this paper. The results show that the magnetic distribution depends on both the stress status and the environmental magnetic field. But these two factors often have quite different mechanisms; the distribution of magnetic field depends on the powerful one.

Artifact properties of carbon nanotube yarn electrode in magnetic resonance imaging

OBJECTIVE Deep brain stimulating (DBS) is a rapidly developing therapy that can treat many refractory neurological diseases. However, the traditional DBS electrodes which are made of Pt-Ir alloy may induce severe field distortions in magnetic resonance imaging (MRI) which leads to artifacts that will lower the local image quality and cause inconvenience or interference. A novel DBS electrode made from carbon nanotube yarns (CNTYs) is brought up to reduce the artifacts. This study is therefore to evaluate the artifact properties of the novel electrode. APPROACH We compared its MR artifact characteristics with the Pt-Ir electrode in water phantom, including its artifact behaviors at different orientations as well as at various off-center positions, using both spin echo (SE) and gradient echo (GE) sequences, and confirmed its performance in vivo. MAIN RESULTS The results in phantom showed that the CNTY electrode artifacts reduced as much as 62% and 74% on GE and SE images, respectively, compared to the Pt-Ir one. And consistent behaviors were confirmed in vivo. The susceptibility difference was identified as the dominant cause in producing artifacts. SIGNIFICANCE Employing the CNTY electrode may generate much less field distortion in the vicinity, improve local MR image quality and possibly be beneficial in various aspects.