Molecular dynamics simulation and neutron scattering studies of nonaqueous electrolyte solutions

Nonaqueous electrolyte solutions have been widely investigated for a variety of applications due to their outstanding properties such as high conductivity and excellent stability. However, establishment of predictive models for nonaqueous electrolytes remains challenging. Molecular packing and clustering effects in complex liquid systems such as redox-active electrolyte solutions are still poorly understood especially at high concentrations. Here, neutron scattering is used to probe the dynamics at molecular level in nonaqueous organic electrolytes over a wide temperature range. Two model solution systems were chosen: one containing highly symmetric electrolyte molecules prone to crystallization and one containing a de-symmetrized liquid electrolyte preferring disordered states. In the latter case, complete supercooling (preservation of a disordered state below the melting point without crystallization) was observed to very low temperatures at high concentrations. However, upon heating, localized cold crystallization occurs, leading to a burst nucleation of microcrystalline solids within liquid-like components. Our findings indicate the clustering in these materials and point out limits in solvation and molecular crowding in concentrated nonaqueous electrolyte fluids. Although molecular dynamics (MD) simulation is promising method to predict numerous properties of nonaqueous electrolytes, quantitative predictions depend critically on the prescribed force fields. We show that several quantum-mechanically refined force fields for the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) - acetonitrile electrolyte yield structures agreeing well with the experimental neutron pair distribution function (PDF), yet produce dramatically different dynamics disagreeing with NMR measurements. Such glaring discrepancies indicate that inadequate representation of long-range interactions leads to excessive frustration in the free energy landscape. Better agreement is achieved by proportionally scaling down the atomic charges of the ions. This simplification enabled the simulation of concentration dependences of ionic diffusion for 0.2-2 M LiTFSI solutions without sacrificing fit quality of the PDFs. We argue that not only structures but also dynamics constitute important checkpoints towards to computationally design functional electrolytes

Statistical Vehicle Specific Power Profiling for Urban Freeways

AbstractVehicle Specific Power (VSP) is conventionally defined to represent the instantaneous vehicle engine power. It has been widely utilized to reveal the impact of vehicle operating conditions on emission and energy consumption estimates that are dependent upon speed, roadway grade and acceleration or deceleration on the basis of the second-by-second vehicle operation. VSP has hence been incorporated into a key contributing factor in the vehicle emission models including MOVES. To facilitate the preparation of MOVES vehicle operating mode distribution inputs, an enhanced understanding and modeling of VSP distribution versus roadway grade become indispensable. This paper presents a study in which previous studies are extended by deeply investigating the characteristics of VSP distributions and their impacts due to varying freeway grades, as well as time-of-day factors. Afterwards, statistical distribution models with a scope of bins is identified through a goodness of fit testing approach by using the sample data collected from the interstate freeway segments in Cincinnati area. The Global Positioning System (GPS) data were collected at a selected length of 30km urban freeway for AM, PM and Mid-day periods. The datasets representing the vehicle operating conditions for VSP calculation are then extracted from the GPS trajectory data. The distribution fit modeling results demonstrated that the Wakeby distribution with five parameters dominates the most fitting parameters with the samples. In addition, the speed variation lies behind the time of day differences is also identified to be a contributing factor of urban freeway VSP distribution

The Chinese Dream and Strategy of College Students’ Growth and Success

The Chinese dream is a dream of the people in the final analysis. College students are the builders and successors of the cause of socialist modernization, and are the main force and reserve army to achieve the Chinese dream. Today, college students undertake the future mission to fully build a moderately prosperous society and achieve socialist modernization. In order to complete the mission and boost realization of the Chinese dream, college students should have ideological, political and moral qualities, professional knowledge, professional competencies, physical and mental qualities. At the same time, we should realize college students’ dream of success from three dimensions as follows, universities should attach importance to talents, teachers should strive to be “four haves’ teachers to foster talents, students should cherish ambitious dream to seek success.  

Correlation between resistance of eggplant and defense-related enzymes and biochemical substances of leaves

14 eggplant cultivars were inoculated by Verticillium dahliae to screen their resistance against verticillium wilt. The resistances were shown as the disease incidence and disease index, and eggplant cultivars were classified into resistant type (R), moderate resistant type (MR), tolerant type (T), moderate susceptible (MS) and susceptible type (S), according to the final disease index. To find out the correlated physiological and biochemical indexes for evaluating the resistance of eggplant to verticillium wilt, the activities of defense-related enzymes, and the contents of some biochemical substances of leaves were investigated. The results show that the activities of polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were significantly positively correlated with resistance (P <0.01) and the resistance was significantly positively correlated with the activity of peroxidase (POD) and the content of total chlorophyll (P<0.05), but significantly negatively correlated with the relative electric conductivity and the content of malondialdehyde (MDA) (P<0.05). The correlations between resistance and catalase (CAT) activity, the contents of sucrose, soluble protein and proline, were not detected.Keywords: Verticillium wilt, eggplant, disease resistance, defense-related enzyme, biochemical substanc

Analgesia for total knee arthroplasty: a meta-analysis comparing local infiltration and femoral nerve block

Patients frequently experience postoperative pain after a total knee arthroplasty; such pain is always challenging to treat and may delay the patient’s recovery. It is unclear whether local infiltration or a femoral nerve block offers a better analgesic effect after total knee arthroplasty.We performed a systematic review and meta-analysis of randomized controlled trials to compare local infiltration with a femoral nerve block in patients who underwent a primary unilateral total knee arthroplasty. We searched Pubmed, EMBASE, and the Cochrane Library through December 2014. Two reviewers scanned abstracts and extracted data. The data collected included numeric rating scale values for pain at rest and pain upon movement and opioid consumption in the first 24 hours. Mean differences with 95% confidence intervals were calculated for each end point. A sensitivity analysis was conducted to evaluate potential sources of heterogeneity.While the numeric rating scale values for pain upon movement (MD-0.62; 95%CI: -1.13 to -0.12; p=0.02) in the first 24 hours differed significantly between the patients who received local infiltration and those who received a femoral nerve block, there were no differences in the numeric rating scale results for pain at rest (MD-0.42; 95%CI:-1.32 to 0.47; p=0.35) or opioid consumption (MD 2.92; 95%CI:-1.32 to 7.16; p=0.18) in the first 24 hours.Local infiltration and femoral nerve block showed no significant differences in pain intensity at rest or opioid consumption after total knee arthroplasty, but the femoral nerve block was associated with reduced pain upon movement

In vitro apatite formation and drug loading/release of porous TiO2 microspheres prepared by sol-gel processing with different SiO2 nanoparticle contents

Bioactive titania (TiO2) microparticles can be used as drug-releasing cement fillers for the chemotherapeutic treatment of metastatic bone tumors. Porous anatase-type TiO2 microspheres around 15 μm in diameter were obtained through a sol–gel process involving a water-in-oil emulsion with 30:70 SiO2/H2O weight ratio and subsequent NaOH solution treatment. The water phase consisted of methanol, titanium tetraisopropoxide, diethanolamine, SiO2 nanoparticles, and H2O, while the oil phase consisted of kerosene, Span 80, and Span 60. The resulting microspheres had a high specific surface area of 111.7 m2·g− 1. Apatite with a network-like surface structure formed on the surface of the microspheres within 8 days in simulated body fluid. The good apatite-forming ability of the microspheres is attributed to their porous structure and the negative zeta potential of TiO2. The release of rhodamine B, a model for a hydrophilic drug, was rapid for the first 6 h of soaking, but diffusion-controlled thereafter. The burst release in the first 6 h is problematic for clinical applications; nonetheless, the present results highlight the potential of porous TiO2 microspheres as drug-releasing cement fillers able to form apatite

In vitro apatite formation and drug loading/release of porous TiO2 microspheres prepared by sol-gel processing with different SiO2 nanoparticle contents

Bioactive titania (TiO2) microparticles can be used as drug-releasing cement fillers for the chemotherapeutic treatment of metastatic bone tumors. Porous anatase-type TiO2 microspheres around 15 μm in diameter were obtained through a sol–gel process involving a water-in-oil emulsion with 30:70 SiO2/H2O weight ratio and subsequent NaOH solution treatment. The water phase consisted of methanol, titanium tetraisopropoxide, diethanolamine, SiO2 nanoparticles, and H2O, while the oil phase consisted of kerosene, Span 80, and Span 60. The resulting microspheres had a high specific surface area of 111.7 m2·g− 1. Apatite with a network-like surface structure formed on the surface of the microspheres within 8 days in simulated body fluid. The good apatite-forming ability of the microspheres is attributed to their porous structure and the negative zeta potential of TiO2. The release of rhodamine B, a model for a hydrophilic drug, was rapid for the first 6 h of soaking, but diffusion-controlled thereafter. The burst release in the first 6 h is problematic for clinical applications; nonetheless, the present results highlight the potential of porous TiO2 microspheres as drug-releasing cement fillers able to form apatite