Gravity and Neuronal Adaptation

Introduction: For interplanetary and orbital missions in human space flight, knowledge about the gravity-sensitivity of the central nervous system (CNS) is required. The objective of this study was to assess neurophysiological correlates in variable hetero gravity conditions in regard to their timing and shaping. Methods: In ten subjects, peripheral nerve stimulation was used to elicit H-reflexes and M-waves in the M. soleus in Lunar, Martian, Earth and hypergravity. Gravity-dependencies were described by means of reflex latency, inter-peak-interval, duration, stimulation threshold and maximal amplitudes. Experiments were executed during the CNES/ESA/DLR JEPPFs. Results: H-reflex latency, inter-peak-interval and duration decreased with increasing gravitation (P<0.05); likewise, M-wave inter-peak-interval was diminished and latency prolonged with increasing gravity (P<0.05). Stimulation threshold of H-reflexes and M-waves decreased (P<0.05) while maximal amplitudes increased with an increase in gravitation (P<0.05). Conclusion: Adaptations in neurophysiological correlates in hetero gravity are associated with a shift in timing and shaping. For the first time, our results indicate that synaptic and axonal nerve conduction velocity as well as axonal and spinal excitability are diminished with reduced gravitational forces on the Moon and Mars and gradually increased when gravitation is progressively augmented up to hypergravity. Interrelated with the adaptation in threshold we conclude that neuronal circuitries are significantly affected by gravitation. As a consequence, movement control and countermeasures may be biased in extended space missions involving transitions between different force environments.     

Scopolamine sublingual spray: an alternative route of delivery for the treatment of motion sickness

The purpose of this study was to develop a sublingual drug delivery spray formulation of scopolamine hydrobromide (L-(-)-hyoscine hydrobromide) and to determine the absolute bioavailability of scopolamine hydrobromide following sublingual delivery and to investigate the effect of a bioadhesive on the pharmacokinetic parameters of this drug in a rabbit model. Rabbits received a single scopolamine free base equivalent sublingual dose of 100 microg/kg and this was compared to intravenous administration of the drug. Blood samples were collected at different time points, and plasma scopolamine concentrations were determined using a new sensitive and specific LC/MS analytical method which utilized electrospray ionization detection. The bioavailability of sublingual scopolamine was determined by comparing plasma concentrations after sublingual spray delivery with equivalent intravenous doses. Following delivery of the sublingual spray dose, the average Cmax was 1024.4+/-177 ng/mL, and the AUC value was found to be 61067.6+/-9605 ng.min/mL. Relative to the intravenous dose (100% bioavailability), the bioavailability was 79.8% after sublingual spray administration. The addition of 2% chitosan, a bio-adhesive material and an absorption enhancer, showed a significant improvement in scopolamine sublingual absorption (p<0.05) was observed. Considering the limitations of delivering scopolamine orally or transdermally to patients who experience motion sickness, the sublingual route of administration using a spray delivery dosage form, is a potential alternative modality for the prevention of nausea and vomiting associated with motion sickness.     

Scopolamine Sublingual Spray: An Alternative Route of Delivery for the Treatment of Motion Sickness

ABSTRACT

The purpose of this study was to develop a sublingual drug delivery spray formulation of scopolamine hydrobromide (L-(-)-hyoscine hydrobromide) and to determine the absolute bioavailability of scopolamine hydrobromide following sublingual delivery and to investigate the effect of a bioadhesive on the pharmacokinetic parameters of this drug in a rabbit model. Rabbits received a single scopolamine free base equivalent sublingual dose of 100 μg/kg and this was compared to intravenous administration of the drug. Blood samples were collected at different time points, and plasma scopolamine concentrations were determined using a new sensitive and specific LC/MS analytical method which utilized electrospray ionization detection. The bioavailability of sublingual scopolamine was determined by comparing plasma concentrations after sublingual spray delivery with equivalent intravenous doses. Following delivery of the sublingual spray dose, the average C_max was 1024.4 ± 177 ng/mL, and the AUC value was found to be 61067.6 ± 9605 ng.min/mL. Relative to the intravenous dose (100% bioavailability), the bioavailability was 79.8% after sublingual spray administration. The addition of 2% chitosan, a bio-adhesive material and an absorption enhancer, showed a significant improvement in scopolamine sublingual absorption (p < 0.05) was observed. Considering the limitations of delivering scopolamine orally or transdermally to patients who experience motion sickness, the sublingual route of administration using a spray delivery dosage form, is a potential alternative modality for the prevention of nausea and vomiting associated with motion sickness.     

Cross-layer cooperation for accurate admission control decisions in mobile ad hoc networks

Mobile ad hoc networks (MANETs) are unpredictable by nature. Providing any kind of reliability for quality of service (QoS) in such networks is challenging. Quantifying available resources accurately, avoiding interference with ongoing QoS traffic and adapting to QoS violations caused by nodes' mobility are the main concerns for the design of an efficient admission control protocol in MANETs. Adaptive admission control (AAC), a novel admission control protocol which uses robust and accurate resource estimation and prediction techniques for relevant admission decisions has been proposed. Furthermore, AAC uses statistical QoS provision to counteract the QoS threatening mobility. Through simulations, we show that our proposed scheme outperforms existing approaches in terms of correctness and overall performance.     

无机填料对木粉/高密度聚乙烯复合材料性能的影响

目的考察无机填料的种类、粒径以及添加量对PF/HDPE复合材料力学性能和热稳定性的影响。方法以杨木纤维(PF)、高密度聚乙烯(HDPE)、BaSO4、CaCO3、云母粉为原料,采用熔融共混和注塑成型的方法制备PF/HDPE复合材料,进行力学、热重、扫描电镜测试分析。结果3种无机填料均改善了PF/HDPE复合材料力学及热稳定性能,填充CaCO3获得的复合材料性能优于填充BaSO4、云母粉获得的复合材料,并且随着填料颗粒粒径的减少,改善效果增强。填料的添加量需要保持在一定范围内,添加量过低或过高均会造成性能下降。结论添加CaCO3(质量分数为9%,3000目)制备的PF/HDPE复合材料具有最佳的力学及热稳定性。     

Electron Injection via Interfacial Atomic Au Clusters Substantially Enhance the Visible-Light-Driven Photocatalytic H2 Production of the PF3T Enclosed TiO2 Nanocomposite

A hybrid composite of organic–inorganic semiconductor nanomaterials with atomic Au clusters at the interface decoration (denoted as PF3T@Au-TiO₂) is developed for visible–light-driven H₂ production via direct water splitting. With a strong electron coupling between the terthiophene groups, Au atoms and the oxygen atoms at the heterogeneous interface, significant electron injection from the PF3T to TiO₂ occurs leading to a quantum leap in the H₂ production yield (18 578 µmol g⁻¹ h⁻¹) by ≈39% as compared to that of the composite without Au decoration (PF3T@TiO₂, 11 321 µmol g⁻¹ h⁻¹). Compared to the pure PF3T, such a result is 43-fold improved and is the best performance among all the existing hybrid materials in similar configurations. With robust process control via industrially applicable methods, it is anticipated that the findings and proposed methodologies can accelerate the development of high-performance eco-friendly photocatalytic hydrogen production technologies.     

Decision-making processes evaluation using two methodologies: field and simulation techniques

The study of information processing and human actions in complex environments requires the use of methodological tools that enable one to comprehend the complexity of context without sacrificing methodological accuracy, control of variables or results generalization. Research methods that allow the study of strategies that people use when they make decisions are, among others, field studies and simulated micro-worlds. The aim of this paper is to present the main theoretical and methodological conclusions obtained in two studies centred on decision-making processes. The authors were interested in evaluating the results obtained both in a previous field study developed with experts in process control tasks and in a simulated study with inexperienced people. In the field study, a verbal protocol technique was used, while in the simulated study a simulated dynamic task was developed which contained the main features of control process tasks. Among other factors, the authors are interested in exploring the effect of expertise with the task, the learning strategies and the ways of task solving. The results of these two studies indicate some characteristics of a good performance such as the importance of information searches; the taking into account of delays in the effects of the actions; the anticipation of possible system changes.     

The synergistic effect of environmental sustainability and corporate reputation on market value added (MVA) in manufacturing firms

This study is an attempt to explore the predictive effect, in terms of operational capability, of a large manufacturing firm’s environmental greening efforts carried out in the interest of sustainability, and of the firm’s reputation for social responsibility. Through both a traditional and a new, innovative approach, this study investigates the potential synergistic effect of environmental sustainability and the improvement of corporate reputation on a firm’s market performance in terms of shareholders’ equity value (market value added, or MVA) when taken together with the firm’s other key differential business factors. The findings of this study provide notable implications that establish the integrative paradigm for the influence of environmental greening sustainability on firm performance through the use of an innovative methodological approach regardless of a priori theoretical assumptions. Through this, the impact of environmental sustainability and corporate reputation, as well as their synergistic effect, on firm performance push forward a new foundation in business practice. The major findings and new methodological approach (Back-Propagation Neural Networks; BPNN) in this study will open a broad new spectrum of opportunities for further research on these topical issues.     

Remaining useful life prediction for lithium-ion batteries using a quantum particle swarm optimization-based particle filter

ABSTRACT

A novel RUL prediction approach for lithium-ion batteries using quantum particle swarm optimization (QPSO)-based particle filter (PF) is proposed. Compared to particle swarm optimization (PSO)-based PF, QPSO-based PF is proved to have a better performance in global searching and has fewer parameters to control, which makes QPSO-PF easier for applications. Moreover, fewer particles are required by QPSO-PF to accurately track the battery's health status, leading to a reduction of computation complexity. RUL prediction results using real data provided by NASA and compared with benchmark approaches demonstrates the superiority of the proposed approach.     

Driving simulator sickness: Impact on driving performance,influence of blood alcohol concentration,and effect of repeated simulator exposures

Simulator sickness is a major obstacle to the use of driving simulators for research, training and driver assessment purposes. The purpose of the present study was to investigate the possible influence of simulator sickness on driving performance measures such as standard deviation of lateral position (SDLP), and the effect of alcohol or repeated simulator exposure on the degree of simulator sickness. Twenty healthy male volunteers underwent three simulated driving trials of 1 h’s duration with a curvy rural road scenario, and rated their degree of simulator sickness after each trial. Subjects drove sober and with blood alcohol concentrations (BAC) of approx. 0.5 g/L and 0.9 g/L in a randomized order. Simulator sickness score (SSS) did not influence the primary outcome measure SDLP. Higher SSS significantly predicted lower average speed and frequency of steering wheel reversals. These effects seemed to be mitigated by alcohol. Higher BAC significantly predicted lower SSS, suggesting that alcohol inebriation alleviates simulator sickness. The negative relation between the number of previous exposures to the simulator and SSS was not statistically significant, but is consistent with habituation to the sickness-inducing effects, as shown in other studies. Overall, the results suggest no influence of simulator sickness on SDLP or several other driving performance measures. However, simulator sickness seems to cause test subjects to drive more carefully, with lower average speed and fewer steering wheel reversals, hampering the interpretation of these outcomes as measures of driving impairment and safety. BAC and repeated simulator exposures may act as confounding variables by influencing the degree of simulator sickness in experimental studies.     

Development of adaptive injection flow rate and pressure control algorithms for resin transfer molding

To prevent dry spot formation during fabrication of composite parts by Resin Transfer Molding (RTM), a control interface and four different adaptive control algorithms have been developed and tested with numerical simulations. The interface is capable of controlling the flow pattern of resin as it fills a mold containing a preform of fiber reinforcement, provided that the mold is equipped with multiple inlet gates, a single vent and a spinal sensor system that continuously feeds the interface with the resin flow front locations along the spine lines connecting the inlet gates to the vent. Four different adaptive control algorithms targeting on injection flow rate control, injection pressure control, linearly-corrected pressure control, and the combined flow rate and linearly-corrected pressure control have been proposed and incorporated with the control interface. To provide desirable controllability of the filling process and effective utilization of the resin dispensing equipment, the final formulations were optimized by means of numerical simulations of a rectangular RTM part containing different permeability distributions. The results were compared to investigate the strengths and weaknesses of the spinal adaptive control algorithms in terms of dry spot size, filling speed, and the minimum responding speed of injection pump. Finally, a complex geometry case study was conducted to validate and highlight the spinal adaptive control algorithms’ capability in handling flow disturbance for a complex RTM mold filling process which involves irregular mold geometry, multiple inserts, significant permeability and racetracking variations, and non-straight spinal sensors.     

Stability analysis of ITER Poloidal Field Coils conductors

The stability analysis [1] of the Poloidal Field Coils of the ITER Project, specially the PF5, PF3 and PF2 coils for scenario #2, normal mode has been performed using the Gandalf [2] code. The conductor stability is assessed in the most severe operating conditions, at the minimal temperature margin time of the 4th pulse. It consists in determining the maximal deposited energy (perturbation in mJ/cm³ of superconducting strands) which can be absorbed without runaway. This study is performed for three initial different designs: Cu–nonCu ratio of 2.3, 1.6 and 4.4 for PF5, and Cu–nonCu ratio of 2.3, 1.6 and 6.9 for PF3 and PF2. The results are presented as well as a discussion about the phenomena, important parameters and uncertainties. For each type of perturbation, the calculated stability limits are quite similar from one design to another. The low Cu–nonCu ratios do not show significant stability degradation compared to the original ITER design with high ratios.     

Feasibility of online collaborative voltage stability control of power systems

The authors present the results of feasibility study of a novel concept of power system online collaborative voltage stability control. Online collaboration between power system controllers is proposed in order to enhance their overall performance and efficiency to cope with the increasing operational uncertainty of modern power systems. The framework of the proposed online collaborative voltage stability control is first presented, which is based on the deployment of multi-agent systems and real-time communication for online collaborative control. Then, two of the most important issues in implementing the proposed online collaborative voltage stability control are addressed: (1) Error-tolerant communication protocol for fast information exchange among multiple intelligent agents; (2) Deployment of multi-agent systems by using graph theory to implement power system post-emergency control. Results of testing the proposed online collaborative voltage stability control in the case of the 10-machine 39-node New England power system are presented. Results of a feasibility study by means of a simulation are given that take into consideration low-probability cascading faults in the power system.     

An all solid-state narrow bandwidth optical parametric oscillator and its applications to the high resolution spectroscopy of free radicals

The paper describes the design, performance and illustrative spectroscopic applications of a high power, pulsed, injection seeded, narrow bandwidth and continuously tuneable optical parametric oscillator (OPO) based on two β-barium borate (BBO) nonlinear crystals. A ring cavity OPO was injection seeded with an external cavity diode laser in the spectral range 755–855 nm. The OPO generated high power transform limited nanosecond light pulses in this range and, simultaneously, at 606–667 nm. Spectral parameters of the OPO were investigated as a function of pump power for two different cavity lengths. A bandwidth of ～120 MHz (0.004 cm^-1) in the visible has been achieved with a 40-cm-long cavity. The potential of the OPO system is demonstrated by recording high resolution sub-Doppler spectra in the UV of PF and C₃ radicals in a pulsed supersonic jet expansion.     

Biomimetic approaches to the control of underwater walking machines

We have developed a biomimetic robot based on the American lobster. The robot is designed to achieve the performance advantages of the animal model by adopting biomechanical features and neurobiological control principles. Three types of controllers are described. The first is a state machine based on the connectivity and dynamics of the lobster central pattern generator (CPG). The state machine controls myomorphic actuators based on shape memory alloys (SMAs) and responds to environmental perturbation through sensors that employ a labelled-line code. The controller supports a library of action patterns and exteroceptive reflexes to mediate tactile navigation, obstacle negotiation and adaptation to surge. We are extending this controller to neuronal network-based models. A second type of leg CPG is based on synaptic networks of electronic neurons and has been adapted to control the SMA actuated leg. A brain is being developed using layered reflexes based on discrete time map-based neurons.     

基于纸纤维/晶须状碳纳米管/活性炭三元无金属集流体复合纸电极的柔性超级电容器

以纸纤维(PF)为基体,晶须状碳纳米管(WCNT)和活性炭(AC)为功能添加物,采用真空抽滤法制成PF/WCNT/AC三元无金属集流体复合电极。利用扫描电子显微镜(SEM)、X射线衍射(XRD)光谱仪、拉曼(Raman)光谱仪对其进行表征和分析,采用两电极测试体系对组装的超级电容器性能进行测试。结果表明,与涂布法所得的铝箔集流体(Al/WCNT/AC)电极相比,由PF/WCNT/AC三元复合电极组装的超级电容器比电容大幅提高,并展现出良好的充放电性能。在1mV/s的扫描速率下比电容达325F/g,几乎是Al/WCNT/AC超级电容器(108.7F/g)的3倍。PF/WCNT/AC超级电容器在0.4A/g电流密度下的比电容为95F/g,在3.2A/g电流密度下的比能量与比功率分别为36.76 Wh/kg、5.52kW/kg。     

添加致孔剂制备树脂基活性炭及电容性能研究

以碱性条件下合成的热固性酚醛树脂(PF)为原料,聚乙烯醇缩丁醛(PVB)和聚乙烯二醇(PEG)为致孔剂,采用聚合物共混炭化活化法制备双电层电容器用活性炭材料.通过热重(TG)分析探讨了PF,PF与PVB、PEG的共混物在炭化过程中的热解行为.考察了活化温度和活化时间对所得活性炭的收率、BET比表面积、孔径分布和比电容的影响,并进一步探讨了以这种活性炭材料作电极的双电层电容器的电容性能.结果表明,随着活化温度的升高,活化温度对活性炭收率的影响更为显著,所得活性炭的收率下降.聚合物PEG较PVB更适合作为成孔剂来控制活性炭的中孔孔径分布.酚醛树脂基活性炭电极比电容在850℃活化1 h为79.2F/g,而聚乙烯二醇/酚醛、聚乙烯醇缩丁醛/酚醛混合树脂基活性炭电极比电容则分别高达130.5和145.6F/g.     

Microscopic, physical and mechanical analysis of polypropylene fiber reinforced concrete

This investigation examined the reinforcing effects and mechanisms of polypropylene fiber (PF) on the physical and mechanical properties of concrete. Scanning electron microscope (SEM) was used to observe the crystal structures and that at the aggregate-cement interfacial transition zone. Physical and mechanical tests were performed to measure the effects of PF on improving concrete's engineering properties. Results indicate that PF significantly alters the microstructure of concrete, reduces the crystallization and orientation of Ca(OH)₂, and decreases micro-voids. Specifically, PF forms a network that restricts the growth of Ca(OH)₂, bridges cracking, and reallocates stresses. PF has reduced the amount and size of crystalline, and the micro-cracking at the aggregate-cement interfacial transition zone. As a result, PF has effectively improved concrete's compressive strength, flexural strength, bonding strength, dynamic performance, and fatigue life, while reduced the water penetration and abrasion mass loss. Results also indicate that a PF content of 0.9 kg/m³ has the optimum concrete performance output for the materials used in this study.     

Improved photovoltaic properties of fluorene-thiophene-based copolymers by an electron-transporting triazole unit in the main chain

An electron-transporting triazole (Tz) unit was introduced into the fluorene-thiophene-based copolymer backbone via a Suzuki coupling reaction. The resulting copolymer, poly[9,9'-dioctyl-fluorene-co-5, 5-(4', 7'-di-2-thienyl-2', 1',3'-benzothiadiazole)-co-(4-(4-butyl-phenyl)-3, 5-diphenyl-4H-1,2,4]triazole)] (PF3TBTz), was soluble in common organic solvents and can be easily used as the active layer in organic photovoltaic cells (OPVs). By the introduction of the triazole unit, the OPV performance was nearly doubled from 0.62% (PF3TB) to 1.25% (PF3TBTz) under the same conditions. The higher performance can be explained by the improved surface morphology, resulting in better charge photogeneration and higher short circuit current (J(sc)) value in PF3TBTz in comparison with PF3TB. The possibility of the use of triazole units in OPV applications are described herein.     

Performance evaluation of a vapor injection heat pump system for electric vehicles

Battery-powered electric vehicles (EV) need an efficient electric heating system for extending the driving mileage. An air-source heat pump system offers an economical alternative for EV because it consumes less energy than a heating system using Joule heat and it can use the same components as an air conditioning system for cooling. However, its performance degradation is inevitable at very low ambient temperatures. Although vapor refrigerant injection is known as a good technology to overcome this problem in residential heat pump systems, the number of vapor injection heat pump studies for EV applications is quite limited. In this paper, considering the characteristics of EV application, the configuration of a vapor injection heat pump system for EV is introduced, and it was modeled, using a scroll compressor geometry-based thermodynamic analysis. The performance was estimated for cold ambient regions under the EV operational conditions.