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Transformation of allylic alcohols to corresponding saturated carbonyl compounds is one of the important reactions for industrial processes. Lately, Au-supported catalysts exhibit the catalytic activity for the isomerization of allylic alcohols to saturated aldehydes. However, the detail catalytic mechanism of this reaction was not elucidated in detail. Thus, theoretical calculations were carried out for the isomerization of 2-hexen-1-ol over isolated Au6 cluster in order to elucidate the reaction over Au catalysts. From these calculation results, it was found that the rate determining step of the reaction process was the hydrogen elimination from OH group of allylic alcohol, and the substrate was converted to 1-hexen-1-ol on Au6 cluster. Finally, it was also confirmed that 1-hexen-1-ol was converted to the corresponding aldehyde, and its activation barrier was much smaller than that of the deprotonation from OH group of allylic alcohol.
Analog Devices is a large multinational corporation. The risks involved in the manufacturing process for Analog are accordingly colossal. What are the avenues open to a company for controlling these risks? Is diversifying risk management the best answer? What is a feasible cost-effective risk management program for a company of this size?
LiNi0.5Mn1.5O4−x F x (0≤ x ≤0.1) cathodes, synthesized by ultrasonic spray pyrolysis at 900°C, exhibit superior structural and electrochemical properties. The samples are characterized by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and electrochemical measurements. During Li+ extraction, LiNi0.5Mn1.5O4−x F x has a smaller lattice variation and area-specific impedance than LiNi0.5Mn1.5O4. This enhances the rate capability, especially at high C-rates. LiNi0.5Mn1.5O4−x F x also exhibits better resistance than LiNi0.5Mn1.5O4 to attack by HF.
Using the “between-grade levels” regression discontinuity design, this study examined the hypothesized differential sensitivity of logico-mathematical (LM) and infralogical (IL) operational tasks to the effects of chronological age and first grade schooling in a sample of 580 1st and 2nd grade Israeli children. The results indicate that the development of logico-mathematical operational skills (classification, class inclusion and transitivity) is mainly attributable to schooling. In contrast, the effect of schooling on the development of conservation of mass, liquid quantity and number (clearly an infralogical task) is negligible; acquisition of conservation is almost exclusively due to maturation and out-of-school experiences. The results support the theoretical predictions derived from French-Swiss research of the last two decades and are inconsistent with claims regarding the specificity of schooling effects to tasks that are taught in school.
The charge/discharge, electrochemical impedance, cyclic voltammogram, and cycling behaviors of crystalline K x MnO2·nH2O as cathode material for supercapacitors in Li2SO4, Na2SO4, and K2SO4 electrolytes were compared. The different power and cycling performance of K x MnO2·nH2O during charge/discharge in the three electrolytes were elucidated by analyzing its composition and structure evolution. Compared with the Li2SO4 and Na2SO4 electrolytes, the highest ionic conductivity of K2SO4 electrolyte, the fastest charge-transfer process and slightest structural evolution of K x MnO2·nH2O during charge/discharge in the K2SO4 electrolyte lead to a superior power and cycling behavior for supercapacitor application.
Proton exchange membrane fuel cells (PEMFCs) are an exciting clean energy technology for power delivery for a range of devices from automotive applications through to portable digital equipment. Current technology for PEMFCs is limited by its inability to operate at high temperatures which is particularly desirable for automotive applications. This review summarises and discusses the key areas of research in recent years for non-polymer based high temperature membranes or so-called solid acid membranes. The review addresses: the reasons for operating at high temperatures, the proton transport mechanisms, the limitations of current polymer membranes and their modification and on the future of solid acid membranes elaborating on future pathways which may bring about tangible enhancements in this technology.
In this study, a series of nanocomposite polymer electrolytes (NCPEs) with high conductivity and lithium ion transference number, PEO/LiClO4/SAP, were prepared from high molecular weight polyethylene oxide (PEO), LiClO4 and low content of homemade silica aerogel powder (SAP), which had higher surface area and pore volume than the conventional silica particle. From the SEM images it was found that the SAP nanoparticles were well dispersed in the PEO polymer electrolyte matrix. The characterization and interactions in the CPEs were studied by DSC, XRD, FT-IR and 7Li NMR analysis. The ac impedance results showed that the ionic conductivity of the CPE was significantly improved by the addition of the as-prepared SAP. The maximum ambient ionic conductivity obtained from the CPE with EO/Li=6 and 2wt.% of SAP (O6A2) was about threefold higher than that of the corresponding polymer electrolyte without SAP (O6). In addition, the lithium ion transference number (t +) of O6A2 at 70°C was as high as 0.67, which was also three times higher than that of O6 and has not been previously reported for the PEO–LiX-based polymer electrolytes.
Due to the limited amount of stored battery energy available for electric vehicles, it is important to use the energy in an optimal manner. This study proposes a novel comfortable optimal driving strategy (CODS) to change a speed that presents a number of optimal acceleration(s) to the driver, along with the total acceleration duration and range corresponding to a desired driving comfort. The design of CODS is done by solving a multi-objective optimization problem (MOOP) of minimizing acceleration duration and battery energy consumption. The acceleration jerk was used as a metric to quantify driving comfort. Based on the realization that the system response time should be low without sacrificing solution optimality for online implementation, two MOOPs were solved: constraining the jerk to a maximum level and minimizing the jerk as an optimization objective. Pareto-optimal fronts were obtained and it was found that consideration of minimizing total jerk is more convenient in finding CODS. A plot of the predicted range, time, and comfort for optimal acceleration(s) to a chosen speed change was presented and a comfortable optimal driving zone was identified. The system response time was found to be around 1 s, indicating its suitability for online implementation.
A lumped-parameter thermal model of a cylindrical LiFePO4/graphite lithium-ion battery is developed. Heat transfer coefficients and heat capacity are determined from simultaneous measurements of the surface temperature and the internal temperature of the battery while applying 2Hz current pulses of different magnitudes. For internal temperature measurements, a thermocouple is introduced into the battery under inert atmosphere. Heat transfer coefficients (thermal resistances in the model) inside and outside the battery are obtained from thermal steady state temperature measurements, whereas the heat capacity (thermal capacitance in the model) is determined from the transient part. The accuracy of the estimation of internal temperature from surface temperature measurements using the model is validated on current-pulse experiments and a complete charge/discharge of the battery and is within 1.5 ° C. Furthermore, the model allows for simulating the internal temperature directly from the measured current and voltage of the battery. The model is simple enough to be implemented in battery management systems for electric vehicles.
This paper describes a trajectory by which an individual achieves expertise in group psychotherapy. Five developmental stages are posited. In the decisional-anticipatory stage, interest is developed in group psychotherapy. In the trainee stage, the individual masters the knowledge base of group psychotherapy and obtains fledgling experiences in a group. In the novice stage, the individual obtains additional experience in running groups and becomes socialized into a community of group psychotherapists. In the proficiency stage, the individual narrows his or her group psychotherapy focus and obtains more specialized experience in that area. At this time, supervisory and consultation skills are often developed. In the final stage of expertise, the expert must engage in a process of recognizing its limits and must devise ways to maintain it. Research that focuses on one aspect of expertise, level of experience, is reviewed. Three dimensions of difference are identified: (a) complexity of conceptualization of members and interventions; (b) fostering openness and engagement; and (c) focusing on process.
Plethora of cellular phones has been increasingly driving the spread of e-commerce mechanisms running on mobile devices. For instance, mobile marketing fulfills the wireless delivery (to the devices of mobile users) of the recommended product information and even one-to-one recommendations. One-to-one recommendation not only reduces the time that customers have to expend to for attaining appropriate products, but also is a method to engender customer values and develop the long-term customer relationships. This paper presents a one-to-one recommendation mechanism that iteratively takes as inputs the audio customer messages (together with product information) and produces personalized product analogy structures (that subsequently drive the generation of personalized heterogeneous product recommendations) based on the coupled clustering algorithm. The personalized product analogy structures also evolve as the messages (of the correspondent customer) grow. We have implemented the mechanism with J2EE Web Service that has produced fairly promising evaluation results.
Publisher Summary The chapter defines noise as undesirable signals that are present in a circuit. The three types of noise in analog application are device noise, conducted noise, and radiated noise. Each type of noise has its own set of possible solutions. The first noise type is device noise. Device noise is the intrinsic noise of the devices in the circuit. Examples of device noise would be the thermal noise of a resistor or the shot noise of a transistor. Another type of device noise is the switching noise from a switched mode power supply or a switched capacitor converter. A second type of noise is radiated noise. Radiated noise originates with EMI sources, such as switches or motors. These sources couple radiated noise into a signal. Radiated noise can also transmit from trace to trace on one's printed circuit board (PCB). The third type of noise that affects the performance of analog devices is conductive noise. This type of noise already exists in the conductive paths of a circuit, such as the power lines or signal path. Conducted noise mixes with the desired electrical signal.
The binder-free films of hollow Na2Ti3O7 (NTO) spheres and reduced graphene oxide were employed as anodes for sodium ion batteries. The films were assembled by vacuum filtration of the pre-prepared hollow NTO spheres and reduced graphene oxide nanosheets (NTO-rGO). The ultrathin nanosheets, as the building blocks of hollow spheres, optimize the sodium ion transportation at the particle level. Furthermore, the hollow spheres were employed to prevent the restacking of reduced graphene oxide nanosheets and optimize the sodium ion transportation at electrode level. Thanks to the optimized ion transportation on both particle and electrode levels, the as-prepared NTO-rGO film showed enhanced rate performance of a high capacity of 135 mA h g−1 under the current density of 500 mA g−1 and over 650 cycles, demonstrating the superiority of this unique structure.
Transition metal oxides are widely researched as anode materials for lithium-ion batteries due to their high theoretical capacity. However, the application of this material is always restricted by the low electroconductivity and huge volume change. In this work, we develop a general strategy, the gelatin-assisted hydrothermal-calcination process, to prepare hierarchical porous transition metal oxides and their composites, including Fe2O3, Mn2O3, Co3O4, ZnCo2O4, MnCo2O4 and (Co,Mn)3O4. Depending on the unique molecular structure of gelatin, metal ions in the solution can be located in amino and carboxyl existing in natural polymer, which lead to the formation of hierarchical precursor. Typically, step-like hierarchical porous Fe2O3 and ZnCo2O4 exhibit the outstanding performance of 1301.7 mAh g−1 after 600 cycles and 1005.8 mAh g−1 after 180 cycles at 500 mA g−1 for lithium-ion storage. In addition, Na0.7MnO2 cathode material prepared from MnCO3 also delivers the 140.9 mAh g−1 over 50 cycles at 40 mA g−1 for sodium-ion storage. The stable structure, abundant materials, low toxicity and excellent performance promote the development of anode materials. Moreover, this easily-extended method also provides a strategy to obtain hierarchical materials, which expands the application of transition metal oxides in other fields.
2V/40Ah valve-regulated lead-acid (VRLA) cells have been constructed with negative plates employing carbon black as well as an admixture of carbon black+fumed silica as additives in negative active material for partial-state-of-charge (PSoC) applications. Electrical performance of such cells is compared with conventional 2V/40Ah VRLA cells for PSoC operation. Active material utilization has been found to be higher for carbon-black+fumed-silica mixed negative plates while formation is faster for cells with carbon-black mixed negative plates. Both faradaic efficiency and percentage capacity delivered have been found to be higher for cells with carbon-black+fumed-silica mixed negative plates. However, a high self-discharge rate is observed for cells with carbon-black+fumed-silica mixed negative plates.
Nine different transition metal doped (<10 at%) tin dioxides and undoped SnO2 nanopowders with similar specific surface areas were made using a continuous hydrothermal process and then investigated as potential negative electrode materials for lithium ion batteries. The as-prepared nanopowders were characterized via a range of analytical techniques including powder X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence spectrometry, transmission electron microscopy, thermogravimetric analysis and Brunauer-Emmett-Teller surface area measurements. Doped SnO2 materials were grouped into two classes according to the potential redox activity of the dopant (those presumed to be redox inactive: Nb, Ti, Zr; and those presumed to be redox active: Fe, Co, Cu, Zn, Mn, Ni). The role of the transition metal ion dopant on the cycling performance (overall capacity and voltage hysteresis), was elucidated for the first cycle via cyclic voltammetry measurements in half cells versus lithium metal. In particular, the authors were able to evaluate whether the initial Coulombic efficiency and the delithiation potential (vs. Li/Li+) of the doped samples, would be likely to offer any increased energy density (compared to undoped SnO2) for lithium ion batteries.
Obstructive sleep apnoea (OSA) is a prevalent sleep disorder with significant health consequences. Sleep fragmentation is a feature of OSA and is often determined by the arousal index (ArI), a metric based on the electroencephalograph (EEG). The ArI has a weak correlation with neurocognitive outcomes in OSA patients. In this study, we examine whether changing from the current minimum EEG arousal duration of 3 s improves the association between sleep fragmentation and neurocognitive outcomes.
A 3V lithium ion battery with LiCoPO4 and zero-strain Li4Ti5O12 as insertion material is constructed and investigated. Electrochemical tests show that the full cell displays two operation voltage plateaus (3.24V and 3.17V). Further, the effects of the theoretical capacity matchup ratio between cathode and anode in the LiCoPO4/Li4Ti5O12 cell system on the electrochemical properties are firstly investigated. The LiCoPO4/Li4Ti5O12 cell delivers a highest initial discharge capacity of 135.6 mAh g−1. A 3.2V lithium-ion battery would further extend the application of lithium ion batteries in energy conversion and storage applications.
We present a single crystalline Ge nanowire anode material sheathed with carbon prepared by a solid–liquid solution method. The composite electrode composed of Ge nanowires shows impressive electrochemical properties, exhibiting a very high reversible charge capacity (after lithium removal) of 963 mA h g−1 with a coulombic efficiency of 91%.
Subjective vitality is an indicator of eudaimonic well-being that refers to the feeling of being alive and full of energy. According to Self-Determination Theory (SDT), awareness of what is truly occurring in the present is conducive to subjective vitality. The current study examined the construct validity of the Subjective Vitality Scale and its relation to sociodemographic variables and Experiential Self-Knowledge (ESK), a theoretically relevant awareness construct, in the Lebanese cultural context. A convenient sample of 301 Lebanese adults residing in the Greater Beirut Area completed the Arabic translations of the 6-item Subjective Vitality Scale (SVS) and the 13-item ESK Scale. Exploratory and confirmatory factor analyses supported a unidimensional factor structure for the Arabic SVS. Multiple-group confirmatory factor analyses also provided evidence of configural, metric, structural, and scalar invariance across sex. With respect to sociodemographic variables, sex was the only significant correlate and predictor of subjective vitality, with males reporting greater levels of subjective vitality than females. Consistent with Self-Determination Theory (SDT), awareness as assessed by the ESK Scale was found to be a positive correlate and predictor of subjective vitality such that those who scored higher on experiential self-knowledge also reported greater levels of subjective vitality. These findings provide preliminary support for the construct validity of the Arabic translation of the SVS in the Lebanese context and highlight the potential role of awareness in eudaimonic well-being.
To improve the high-rate capacity and cyclability v.s. temperature, Li2ZrO3 modifies the surface of LiNi1/3Co1/3Mn1/3O2 (LNCM). The crystal structure and electrochemical properties of the bare and coated material are studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT), and charge-discharge tests. The results of PITT exhibit the Li+-ion diffusion coefficient 7.13×10−9 cm2 s−1 of bare LiNi1/3Co1/3Mn1/3O2 increases to 7.9×10−7 cm2 s−1 after coating by Li2ZrO3. At the current rate of 50C, Li2ZrO3-coated LiNi1/3Co1/3Mn1/3O2 (LZO-LNCM) delivers capacity of 104.8 mAh g−1 and maintains 89.3% of the initial capacity after 100 cycles. Carrying out under the temperature of −20°C, LZO-LNCM keeps 73.8% of the initial capacity after 100 cycles, much higher than the value 9.9% of bare LNCM. Li2ZrO3 modification plays the important roles to enhance the high-rate capability and cyclability of LiNi1/3Co1/3Mn1/3O2 at various working temperature.
A process for sputter deposition of RuOx films with high volumetric Li capacities and good cyclability was developed, demonstrating the potential for use of RuOx films as cathodes in high-performance thin-film microbatteries. Using a stoichiometric RuO2 sputtering target, the effects of oxygen content within the Ar/O2 plasma on the stoichiometry of thin films deposited at room temperature was investigated and correlated with electrochemical performance. The oxygen content of the films was found to increase with the O2 to Ar ratio of the sputtering gas. RuOx thin films with x ≥ 1.92 delivering capacities of ∼550 μAh/cm2μm in the 0.75–3.6 V vs. Li/Li+ voltage range, which is much higher than that of under-stoichiometric RuOx (320 μAh/cm2μm). The capacities obtained for RuOx films significantly exceed the capacity of LiCoO2 films (∼60 μAh/cm2μm) typically used in thin-film microbatteries. Given that high capacity RuOx films can be obtained using only room temperature processing, their use in thin-film microbatteries will also allow integration with silicon-based integrated circuits.
The advantages of all-solid-state batteries in terms of high energy density and improved safety have accelerated the research into durable and reliable solid electrolytes and into scale up of their processing technology. High lithium-ion-conducting Li7La3Zr2O12 (LLZO) ceramic-based solid electrolytes have been intensively studied recently, but their widespread commercial deployment has been constrained due to their fragility and brittleness. In the present study, LLZO ceramic powders have been successfully incorporated into the polyethylene oxide (PEO) polymer by tape casting. The ionic conductivity of the PEO/LLZO composite electrolyte membranes is significantly enhanced at the optimal LLZO concentration of 7.5 wt.% at which the materials exhibits maximum ionic conductivity of 5.5 × 10−4 S·cm−1 at 30 °C. The ionic conductivity enhancement mechanism of the composite electrolyte is revealed by differential scanning calorimetry (DSC), which shows that the LLZO filler represses crystallinity in PEO. Furthermore, as evidence of the advantageous electrochemical properties of the composite electrolyte an all-solid-state battery of LiFePO4/Li fabricated herein delivered a maximum discharge capacity of 150.1 mAh·g−1 at 0.1C, good cycling performance, and excellent rate capability under 60 °C.
The effects of surface coating of Y(OH)3 on the electrochemical performance of spherical Ni(OH)2 were studied by cyclic voltammetry (CV) with soft-embedded electrode (SE-E). The coating was performed by chemical surface precipitation under different conditions. The structure, morphology, chemical composition and electrochemical properties of two different samples with surface coating of Y(OH)3 were characterized and compared. The results show that a two-step oxidation process exists in the oxidation procedure of spherical Ni(OH)2 corresponding to the formation of Ni(III) and Ni(IV), respectively. The conversion of Ni(III) to Ni(IV) is regarded as a side reaction in which Ni(IV) species is not stable. The presence of Y(OH)3 on the particle surface can restrain the side reactions, especially the formation of Ni(IV). The application of coated Ni(OH)2 to sealed Ni–MH batteries yielded a charge acceptance of about 88% at 60°C. The results manifest that the high-temperature performance of Ni(OH)2 electrode is related to the distribution of the adding elements in surface oxide layer of Ni(OH)2, the sample with dense and porous coating surface, larger relative surface content and higher utilization ratio of yttrium is more effective.