Nanopumping of water via rotation of graphene nanoribbons.

In this paper, we perform molecular dynamics simulations to propose a novel bio-inspired nanopumping mechanism that is achieved through the rotation of graphene nanoribbons. Due to the rotation and interaction with water, the graphene nanoribbons undergo morphological transformation. It is shown that with appropriate geometrical and spatial parameters, the resulting morphology is twisted ribbon, which is efficient in pumping of water through a channel. This mimics the propulsive behavior of bacterial flagella through continual rotation at the base and causing morphology of the geometry into twisted ribbons, thus driving flow. It was observed that the maximum flux rate decreases upon reaching the optimal configuration even with increasing rotational speed and graphene width. This is due to the development of cavitation near the region of the nanoribbon with tip velocities approaching the speed of sound in water. The simulation shows promising results where the flux rate of the driven flow outperforms various nanopump configurations that have been reported in recent literature by more than one order.

Effects of CNT size on the desalination performance of an outer-wall CNT slit membrane.

We investigate the effect of varying carbon nanotube (CNT) size on the desalination performance through slit confinements formed by horizontally aligned CNTs stacked on top of one another. By increasing the CNT size, the results obtained from this study indicate a corresponding increase in the water flow rate, accompanied by a slight reduction in salt rejection performance. However, due to the increase in the membrane area with CNT size, the permeability performance is observed to reduce as the CNT size increases. Nevertheless, a comparison with nanoporous 2D membranes shows that the permeability of an outer-wall CNT slit membrane remains significantly higher for all CNT sizes considered. This indicates that precise dimensions of the CNTs are not highly crucial for achieving ultra-high permeability performance in such membranes, as long as the critical slit size is maintained. In-depth analytical studies were further conducted to correlate the influence of curvature effects due to increasing CNT size on the flow characteristcis of the outer-wall CNT membrane. These include the analysis of the measured velocity profiles, oxygen density mapping, potential of mean force profile and friction profile. The present numerical results demonstrate the superb desalination performance of the outer-wall CNT slit membrane, regardless of the size of CNTs used. In addition, an extensive analysis conducted provides detailed characterization of how the curvature affects flow across outer-wall CNTs, and can be used to guide future design and fabrication for experimental testing.

On the Performance of Vertically Aligned Graphene Array Membranes for Desalination.

In this paper, we perform molecular dynamics simulations to investigate the performance of multilayer graphene slit membranes. Graphene slit membranes at a critical slit size have been found to be promising desalination membranes. In this contribution, it is shown that multilayer slit membranes have the potential to provide significantly better permeability while retaining outstanding salt rejection. Improved permeability of the membrane is achieved by using slits of widths larger than the critical slit size required to reject salt through size exclusion, and desalination of sea water is performed by increased resistance to salt passage through the multilayering. To facilitate the design process of future multilayer membranes, we analyze the flow resistance of the membrane as a combination of electrical resistors in series and show that this analogy works for membranes where the layers possess the same slit size, as well as membranes with layers of different slit sizes. Comparing with single layer graphene membranes, it was shown that it is possible to obtain 55% improvement in permeability without loss in salt rejection capabilities through multilayering. This opens up possibilities for membrane designers to be free from the restrictions of using a single layer graphene slit membrane with a fixed slit width.

Antifouling Bilayer Graphene Slit Membrane for Desalination of Nanoplastic-Infested Seawater: A Molecular Dynamics Simulation Study.

It has been shown that the nanoplastic particles present in graphene membranes have a high tendency to cause fouling in them due to the high affinity between graphene and nanoplastic molecules. This poses a significant challenge for the use of graphene membranes for desalination. In this paper, we introduce a double-layer graphene slit membrane as a viable solution to significantly reduce fouling caused by the presence of nanoplastic particles in graphene membranes. The molecular dynamics (MD) simulations performed in this work show that when fouling occurs in a single-layer membrane, the presence of nanoplastics reduces the average permeability by close to 40%, from 1877 LMBH to 1148 LMBH, with a large standard deviation of 26% between runs. With the addition of the secondary membrane, the average permeability increases by 17%, with a significantly reduced standard deviation of 7%. These suggest that the secondary layer acts as a sacrificial shield, attracting the nanoplastic contaminants and preventing them from coming into close proximity with the primary membrane, thus preventing fouling at the primary rejection layer. Furthermore, due to the affinity of the nanoplastic particles with the secondary graphene membrane, this membrane design points toward an effective and efficient way of extracting nanoplastic particles for further analysis or processing.

Optimization of sensing and feedback control for vibration/flutter of rotating disk by PZT actuators via air coupled pressure.

In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT) actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin's discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

New Type of Spectral Nonlinear Resonance Enhances Identification of Weak Signals.

Some nonlinear systems possess innate capabilities of enhancing weak signal transmissions through a unique process called Stochastic Resonance (SR). However, existing SR mechanism suffers limited signal enhancement from inappropriate entraining signals. Here we propose a new and effective implementation, resulting in a new type of spectral resonance similar to SR but capable of achieving orders of magnitude higher signal enhancement than previously reported. By employing entraining frequency in the range of the weak signal, strong spectral resonances can be induced to facilitate nonlinear modulations and intermodulations, thereby strengthening the weak signal. The underlying physical mechanism governing the behavior of spectral resonances is examined, revealing the inherent advantages of the proposed spectral resonances over the existing implementation of SR. Wide range of parameters have been found for the optimal enhancement of any given weak signal and an analytical method is established to estimate these required parameters. A reliable algorithm is also developed for the identifications of weak signals using signal processing techniques. The present work can significantly improve existing SR performances and can have profound practical applications where SR is currently employed for its inherent technological advantages.

Safety and Efficacy of the C-117 Formula for Vulnerable Carotid Artery Plaques (Spchim): A Randomized Double-Blind Controlled Pilot Study.

OBJECTIVE: To investigate the safety and efficacy of the Herbal Medicine C-117 (C-117) formula in the treatment of carotid atherosclerotic vulnerable plaques. METHODS: This was a prospective, single-centre, randomized, double-blind study. A total of 120 eligible patients were randomly divided into two groups to receive the C-117 formula or placebo. As the basic treatment, both groups were treated according to the Guidelines for Secondary Prevention of Ischemic Stroke/Transient Ischemic Stroke in China using statins to regulate blood lipids, blood pressure lowering drugs, drugs for controlling blood sugar, and antiplatelet drugs according to the indications. The primary outcomes were the change in stability, the mean change of the plaque Crouse score, and the area and number of bilateral carotid artery plaques before and after 6 months of treatment. The secondary outcomes were the total number of cardiocerebrovascular events during the treatment and follow-up and the mean changes of lipid levels. RESULT: After 180 days of treatment, the plaque Crouse score(95% CI, 0.39 (0.01-0.77), P=0.046) and plaque area (95% CI, 2.14 (-10.10-14.39), P=0.727) were lower in the C-117 formula group than that before treatment. The plaque Crouse score of the control group (95% CI, 0.17 (-0.24-0.57), P=0.417) was lower than that before treatment, while the plaque area (95% CI, -0.35 (-9.35-8.65), P=0.938) increased, but without statistical significance. There was no significant difference in the reduction of the intima-media thickness (IMT), plaque Crouse score, or plaque area between the two groups after treatment (P>0.05). Subgroup analysis of patients whose Lipitor medication time ≥ 20% of the 6-month treatment showed that the levels of total cholesterol, triglycerides, and low-density lipoprotein were lower in the two groups after treatment than before, and the low-density lipoprotein levels in the C-117 formula group significantly decreased (95% CI, 2.99 (-0.08-0.39), P=0.005), but there was no statistical difference between the two groups after treatment (P>0.05). No serious adverse events occurred in the two groups after 180 days of treatment. CONCLUSION: The C-117 formula may be antiatherosclerotic by strengthening statins to reduce the low-density lipoprotein levels and reducing the carotid plaque Crouse scores. Clinical trials with large sample sizes, long-term interventions, and follow-up are needed to investigate the efficacy of the C-117 formula. CLINICAL TRIALS REGISTRATION: This trial is registered with clinicaltrials.gov identifier: NCT03072225 (registered retrospectively on 1st March 2017).

Safety and efficacy of herbal medicine for acute intracerebral hemorrhage (CRRICH): a multicentre randomised controlled trial.

OBJECTIVE: To evaluate the safety and efficacy of removing blood stasis (RBS) herbal medicine for the treatment of acute intracerebral haemorrhage (AICH) within a 6-hour time window. STUDY DESIGN: A randomised, multicentre, double-blind, placebo-controlled study performed in 14 hospitals in China. PARTICIPANTS AND INTERVENTIONS: Patients with AICH were randomly assigned to receive a placebo, the ICH-1 (Intracerebral Haemorrhage) formula (eight herbs, including the RBS herbs hirudo and tabanus) or the ICH-2 formula (six herbs without the RBS herbs hirudo and tabanus) within 6 hours of ICH onset. OUTCOMES: The primary safety outcome was the incidence of haematoma enlargement at 24 hours and at 10 days after treatment. The secondary outcome was the incidence of poor prognosis (mortality or modified Rankin Scale score ≥5) assessed at 90 days after symptom onset. RESULTS: A total of 324 subjects were randomised between October 2013 and May 2016: 105 patients received placebo; 108 patients received the ICH-1 formula; and 111 patients received the ICH-2 formula. The incidence of haematoma enlargement at 24 hours was 7.8% in the placebo group, 12.3% in the ICH-1 group and 7.5% in the ICH-2 group; the incidence of haematoma enlargement on day 10 was 1.1% in the placebo group, 1.1% in the ICH-1 group, and 3.1% in the ICH-2 group, with no significant differences among the groups (P>0.05). The mortality rates were 3.8% in the placebo group, 2.8% in the ICH-1 group, and 0.9% in the ICH-2 group; the incidences of poor prognosis were 7.1% in the placebo group, 6.0% in the ICH-1 group and 4.8% in the ICH-2 group at 3 months, with no significant differences among the groups (p>0.05). However, the overall frequency of treatment-emergent adverse events in the ICH-1 group (12.1%) was higher among the three groups (5.8% and 2.8%, respectively, p<0.05). All three cases of serious adverse events were in the ICH-1 group. CONCLUSIONS: Ultra-early administration of ICH-1 formula for AICH patients did not exert significant beneficial effects on clinical outcomes but increased the risk of bleeding, which probably resulted from the inclusion of RBS herbal medicines in ICH-1. TRIALREGISTRATION NUMBER: NCT01918722.

Clinical re-evaluation of removing blood stasis therapy in treating acute intracerebral hemorrhage safety and efficacy: a protocol for a randomized, controlled, multicenter study (CRRICH Trial).

BACKGROUND: Hypertensive intracerebral hemorrhage (HICH) is one of the most devastating forms of stroke. Currently, no specific therapies for HICH except general medical care. However, in China, medicine of promoting blood circulation (PBC) and removing blood stasis (RBS) are widely and efficiently used to treat HICH and become a potentially effective treatment for the secondary effects of HICH to alleviate brain injury, accelerate neuronal recovery, and improve the prognosis. In order to evaluate the safety and effect of PBC and RBS herbal drugs, we design a prospective, randomized, open, double-blind controlled clinical trial on the hematoma enlargement in HICH patients treating with PBC and RBS herbal medicine within 6 h time window from the symptom onset. METHODS/DESIGN: A multicenter, three-group, prospective, randomized, double-blinded and placebo-controlled clinical trial. Patients aged 18 or older with HICH confirmed by CT scan within 6 h from the onset are included. 360 patients will be randomized to 3 groups (PBC & RBS & Placebo) within 6 h of ictus. Stratified block randomization is undertaken using a sequentially numbered and opaque envelope. All subjects must take medicine within 6 h of ictus and have another CT scan at about 24 h to confirm hematoma expansion. A postal questionnaire to the patients to evaluate their recorvery at 3 months. Primary outcome is the percent change in the volume of hematoma at 24 h. Secondary outcomes include: mortality, disability, serious adverse events, etc. CONCLUSIONS: The CRRICH Trial is expected to confirm the safety and effect of acute intracerebral hemorrhage treated within 6 h of ictus with "RBS" therapy and to determine whether the traditional therapy can cause hematoma growth after intracerebral hemorrhage. DISCUSSIONS: This is the first  prospective, multicenter, randomized, placebo-controlled clinical trial to investigate herbal medicine whether can induce the incidence of hematoma enlargement of AICH patient within the 6 h time window from onset. We need the data to keep the herbal clinical usage safety. Trial registration clinicaltrials.gov: NCT01918722.

Theoretical analysis and measurement of the temperature dependence of a micromachined Fabry-Perot pressure sensor.

In this study an analytical model that takes into account the coupled photoelastic and thermo-optical effects is established to evaluate the temperature dependence of a single-chip silicon micromachined Fabry-Perot pressure sensor. The results show that temperature variation has a significant effect on the performance of a micromachined Fabry-Perot pressure sensor with a conventional flat diaphragm. A new membrane-type silicon micromachined Fabry-Perot pressure sensor with a novel deeply corrugated diaphragm is then proposed. The sensor is fabricated on a single-chip by use of both surface- and bulk-micromachining techniques. Both analytical and experimental results show that the cross sensitivity of Fabry-Perot pressure sensors to temperature can be substantially alleviated by use of the proposed single deeply corrugated diaphragm.

Gaussian-optics-based optical modeling and characterization of a Fabry-Perot microcavity for sensing applications.

A generalized study has been carried out on the modeling of a Fabry-Perot microcavity for sensing applications. Different analytical models on transmission characteristics of a Fabry-Perot microcavity are established by using plane-wave-based techniques, such as the Macleod characteristic matrix technique, the transfer matrix technique, and Smith's technique. A novel Gaussian-optics-based model for a Fabry-Perot microcavity illuminated by a laser beam is then developed and validated. The influence of laser beam waist on microcavity optical response is investigated, and the required minimal beam waist size is explored to ensure a useful optical response for sensing applications that can be accurately predicted by plane-wave optics. Also, the perturbations of microcavity performance induced by different types of microcavity mirror imperfections are discussed, based on the novel optical model. The prototype of the proposed Fabry-Perot microcavity for sensing applications has been successfully fabricated and characterized.