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Bifunctional materials able to catalyze both the oxygen reduction (ORR) and the oxygen evolution (OER) reactions in alkaline media are still a challenge for the progress of energy conversion and storage devices such as metal-air batteries or unitized regenerative fuel cells. In this work, carbon nanofibers synthesized by electrospinning are modified with a combination of cobalt oxide and metallic cobalt (CoO-Co/CNF) and studied as a bifunctional air electrode for metal-air batteries. The performance of CoO-Co/CNF for both reactions is compared with state-of-the-art catalysts such as Pt/C and IrO2. The combination of cobalt oxide and metallic cobalt, finely distributed on the surface of graphitic carbon nanofibers, leads to a bifunctional catalyst with a half-wave potential for the ORR slightly better than Pt/C and a reversibility (ΔEOER-ORR) of 809 mV. The stability of CoO-Co/CNF is assessed by means of different stress tests: polarizations at high electrochemical potentials (2 V vs. RHE), rapid charge-discharge cycles at ±80 mA cm−2 and long durability tests by charging for 12 h at 60 mA cm−2 and discharging for 8 h at −80 mA cm−2. CoO-Co/CNF shows a remarkable stability, maintaining, at least, an 82% of its performance for the ORR after the stress tests, even when cycled for more than 100 h.
Delirium commonly occurs during myeloablative hematopoietic cell transplantation (HCT). Little is known about how delirium during the acute phase of HCT affects long-term distress, health-related quality of life (HRQOL), and neurocognitive functioning. This prospective, cohort study examines these outcomes at 6 months and 1 year in 90 patients undergoing HCT. Patients completed a battery assessing distress, HRQOL, and subjective neuropsychological functioning before receiving their first HCT as well as at 6 months and 1 year. Patients with a delirium episode within the 4 weeks after HCT had significantly more distress and fatigue at 6 months (P < .004) and at 1 year (P < .03), compared with patients without delirium. At 1 year, patients with delirium also had worse symptoms of depression and post traumatic stress (P < .03). Patients with delirium had worse physical health on the SF-12 at 6 months (P < .03) and worse mental health on the SF-12 at 1 year (P < .03). At both 6 months and 1 year, patients with delirium after HCT reported worse memory (P < .009) and executive functioning (P < .006). Delirium during the acute phase of HCT is significantly associated with persistent distress, decreased HRQOL, and subjective neurocognitive dysfunction at both 6 months and 1 year.
Abstract This chapter describes the main strategies for designing clay nanocomposites of the most investigated inherently conductive polymers, namely, polypyrrole, polyaniline, and polythiophenes including poly(3,4-ethylenedioxythiophene) polystyrene sulfonate. It is shown that premodification of clays is an essential step to successful intercalation or exfoliation by conductive polymers. Toward this end, surfactants, reactive diazonium, and silanes permit the preparation of adhesive clay sheets for the conductive polymers once polymerization is triggered. Exfoliated nanocomposites usually exhibit superior properties compared to intercalated ones. Through selected applications (e.g., conductive fillers, catalysts, sensors, ultracapacitors), it is clear that research on clay–conductive polymer nanocomposites will continue to grow because these materials combine the best of two worlds: low-cost abundant minerals with remarkable nanostructural properties and nanostructuring abilities on the one hand and ease of synthesis, reactivity, and electrical conductivity of conjugated polymers on the other hand.
High-energy-density 0.5Li2MnO3–0.5Li(Mn0.375Ni0.375Co0.25)O2 composite cathodes for lithium rechargeable batteries are synthesized using an auto-combustion method. The electrode charge–discharge properties are studied at 25 and 50 °C in Li+-containing N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP–TFSI) and N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMP–TFSI) ionic liquid (IL) electrolytes. The IL electrolytes have a high decomposition temperature (∼400 °C) and thus are ideal for high-safety applications. Compared to Li+/BMP–TFSI IL, Li+/PMP–TFSI IL exhibits higher ionic conductivity and lower viscosity. As a result, the composite cathode shows superior electrochemical performance in Li+/PMP–TFSI IL electrolyte. With the increase in cell temperature from 25 to 50 °C, the maximum capacities and rate capabilities of both IL cells improve significantly. Thus at 50 °C, discharge capacities of 304 mAh g−1 (@10 mA g−1) and 223 mAh g−1 (@100 mA g−1) are obtained for the Li+/PMP–TFSI cell. These capacities are superior to those for a control cell made with the same composite cathode and a conventional organic electrolyte. At elevated temperature, the cyclability of the composite cathode in the IL electrolytes is markedly higher than that obtained in a conventional organic electrolyte.
There is increasing demand for the development of anhydrous proton conducting electrolytes, most notably to allow the development of fuel cells that can operate at temperatures above 120°C, without the need for constant and controlled humidification. The emerging field of protic ionic liquids (PILs) represents a promising new direction for this research and the development of these materials has made significant progress in recent years. In a related but as yet little-explored avenue, proton conducting organic ionic plastic crystals offer the potential advantage of providing a solid state matrix for anhydrous proton conductivity. Here we discuss the recent progress in these areas and identify the key challenges for future research.
Titanium carbide MXene (Ti3C2Tx) possesses a metallic conductivity and an opened nanostructure, being an ideal host for transition metal oxide (TMO) to construct advanced lithium-ion battery anodes. However, Ti3C2Tx is prone to be oxidized under hydrothermal treatment, which limits the growth of TMO/MXene composites through a wet-chemistry approach. Here, we take advantage of the strong electrostatic interaction between SnO2 quantum dots (QDs) and delaminated Ti3C2Tx to protect the latter from oxidation under the hydrothermal condition. The in-situ heterogeneously nucleated SnO2 QDs are tightly anchored on the Ti3C2Tx nanosheets, while the Ti3C2Tx nanosheets effectively limit the growth/aggregation of SnO2. Further freeze-drying of the colloidal mixture results in the SnO2 QDs@Ti3C2Tx composite with conductive Ti3C2Tx nanosheets as backbone, which displays a high specific surface area and abundant voids. The unique architecture design renders SnO2 QDs@Ti3C2Tx a high capacity (1021 mAh g−1 at 100 mA g−1 in the 2.6 mg cm−2 electrode) and long lifetime performance, which maintains 810 mAh g−1 after 200 cycles (100 mA g−1), 697 mAh g−1 after 520 cycles (200 mA g−1) and 500 mAh g−1 after 700 cycles (at 500 mA g−1). More importantly, this wet-chemistry/freeze-drying approach is general, and can be extended to other TMOs and MXenes to fabricate corresponding TMO QDs/MXene composites for various applications.
Nickel hexacyanoferrate (NiHCF) with rigid open framework is promising for energy storage devices, yet still suffer from inferior conductivity and low energy density. Herein, NiHCF supported on diallyldimethylammonium chloride (PDDA) modified graphene (PRGO-NiHCF) was successfully synthesized via a facile co-precipitation method. The size of NiHCF nanoparticals decreased from 50 nm to 20 nm with the introduction of PDDA-induced reduced graphene oxide. The unique structure can not only reversibly accommodate hydrated alkali cations with 3D open-framework, but also facilitate the electrons transportation through the graphene basal plane. Consequently, the as-obtained PRGO-NiHCF exhibits higher specific capacitances of 294 F g−1 at 2 mV s−1 compared to pure NiHCF (176 F g−1). Moreover, under the combination of PRGO-NiHCF positive electrode and the interconnected sandwiched graphene carbon (SGC) negative electrode, the as-assembled asymmetric supercapacitor delivers a wide operation potential of 1.8 V and a high energy density of 25.4 Wh kg−1.
Polycyclic aromatic hydrocarbons (PAHs) are common toxic pollutants found in the aquatic environment, and the assessment of their impact on biota is of considerable concern. The aim of the research described in this paper was to study the biochemical response of a typical fish species, gilthead seabream (Sparus aurata), to two selected PAHs: pyrene and fluorene. For this purpose, in vivo experiments with juvenile seabream exposed to 3 specific concentrations of each compound were conducted (Pyr – 0.02 μM, 0.12 μM and 0.25 μM; and Fluo – 0.12 μM, 0.30 μM and 1.20 μM) and a comprehensive set of biomarkers and gross morphometric indices were measured. For each treatment (concentration), 5 fish in each of 5 aquariums were kept and water was daily renewed. After 4 days of exposure, liver and bile samples were collected. In 2 pooled liver samples per each aquarium 5 biomarkers were tested: Phase I – 7-ethoxyresorufin-O-deethylase (EROD), Phase II – glutathione-S-transferase (GST), antioxidants: catalase (CAT), superoxidase dismutase (SOD), lipid peroxidation (LP). Additionally, fluorescent aromatic compounds (FACs) were analysed in individual bile samples. Moreover, gross morphometric indices: condition factor (CF) and hepatosomatic index (HSI) were calculated for each individual fish. The biotransformation index (BTI) was also calculated. Statistically significant differences (p <0.001) between treatments and control were observed in FACs which were consistently increasing with the increase of the concentration of the pollutants. Moreover, for the highest concentration of pyrene and fluorene, statistically significant inhibition was found in EROD (p <0.01) and CAT (p <0.001 only for fluorene), and induction in SOD (p <0.05, only in the case of fluorene). The results of this research are expected to contribute to the establishment of a good biochemical index of exposure to PAHs in laboratory experiments, which can be further useful in field studies.
The kinetics of the oxygen reduction reaction (ORR) was studied in alkaline electrolyte at 293–333 K on bare and Pd modified Pt(hkl) and Au(hkl) surfaces. The rotating ring-disk electrode technique was used to study the ORR with solution phase peroxide detected at the ring electrode. Pd modification was either by electrodeposition (Pt) or by vapor deposition in vacuum (Au). The surface concentration of Pd was determined in vacuum using low energy ion scattering. In agreement to the structure sensitivity found at room temperature previously, on the bare Au(hkl) surfaces the ORR was found to be strongly structure sensitive in the temperature range from 293 to 333 K, with order of activity being (100)≫(110)>(111). The structure sensitivity for Pt(hkl) is much less and varies in the nearly the opposite order (111)>(100)>(110). The peroxide intermediate pathway is clearly operative on Au(hkl) surfaces. At elevated temperature, significantly smaller amounts of peroxide are formed. The kinetics of the ORR were significantly enhanced by modification of both Pt(hkl) and Au(hkl) surfaces with Pd. The catalytic effect is most pronounced on the surfaces that are less active surfaces in the unmodified state, with enhancement at least an order of magnitude faster kinetics. Pd modification of the Au(hkl) surfaces, therefore, significantly reduces the structure sensitivity of the ORR. Even on the highly active Pt(111) surface the kinetics can be improved by a factor of approximately two to four due to Pd modification. The catalytic enhancement can be achieved with as little as 18 at.% Pd in the Au(hkl) surface.
According to the concept of fetal programming, prenatal distress has long-lasting consequences on the offspring’s health later in life. The hypothalamic-pituitary–adrenal axis is considered a mediating system by which maternal distress is transferred to the fetus in intrauterine environment. In this longitudinal explorative study on 30 mother–child-dyads, reported maternal distress and salivary cortisol were collected during pregnancy. Infant temperament, motor and cognitive development were assessed at 16 months. Additionally, infant cortisol levels throughout the day and in reaction to a psycho-social stressor where measured. As expected, infants whose mothers had experienced higher prenatal distress expressed a more difficult temperament and lower fine motor development at 16 months. No association could be shown between prenatal maternal distress and infant salivary cortisol.
Organic-based energy storage devices are of great interests due to their high potential as affordable, high-performance energy storage devices. Especially, all-organic energy storage devices, where cathode and anode are constituted of organic compounds, could be an extremely affordable device expected to be applied to smart grids. Recent reports on bipolar porous polymeric frameworks (BPPFs) suggest very promising features of this new organic electrode group towards high-performance energy storage devices. Here, we studied an all-organic system using BPPFs for both anode and cathode parts. The formation of BPPFs was confirmed by Raman spectroscopy and N2 isotherm measurements. The electrochemical properties of this all-organic energy storage device using BPPFs showed a high-power density of 1 kW kg−1 based on the total mass of the BPPFs and a long cycle life of over 1000 times.
Writing is a complex task. Its development depends in large part on changes that occur in children’s strategic behavior, knowledge, and motivation. In the present study, the effectiveness of an instructional model, Self-Regulated Strategy Development (SRSD), designed to foster development in each of these areas, was examined. Adding a peer support component to SRSD instruction to facilitate maintenance and generalization was also examined. Struggling, third grade writers, the majority of whom were minority students attending schools that served primarily low-income families, received SRSD instruction focused primarily on learning writing strategies and knowledge for planning and composing stories and persuasive essays. These students wrote longer, more complete, and qualitatively better papers for both of these genres than peers in the comparison condition (Writers’ Workshop). These effects were maintained over time for story writing and generalized to a third uninstructed genre, informative writing. SRSD instruction boosted students’ knowledge about writing as well. The peer support component augmented SRSD instruction by increasing students’ knowledge of planning and enhancing generalization to informative and narrative writing. In contrast, self-efficacy for writing was not influenced by either SRSD condition (with or without peer support).
Polygenic risk scores can predict susceptibility to drug-induced liver injury in patients and can stratify cellular viability of iPSC-derived liver organoids and primary hepatocytes from multiple donors.
Only a few studies have explored cognitive changes with deep brain stimulation (DBS) in patients with essential tremor (ET). Furthermore, the cognitive effects after years of electrical stimulation are unknown. Assessing the impact of stereotactic electrode implantation and the actual electrical stimulation on cognition in patients with ET in the short and long term is of interest, because DBS is increasingly applied and can offer deeper insight into human brain functions. We examined nine ET patients before surgery (PRE-SURGERY), and 1 and 6 years thereafter with DBS switched on (DBS-ON) and off (DBS-OFF). Standardized neuropsychological tests and reaction time tests were applied. There were no differences in tasks of verbal fluency, memory, and executive and intellectual functions comparing PRE-SURGERY, DBS-ON, and DBS-OFF at 1 and 6 years post-surgery. Imaging data revealed that the dorsolateral prefrontal cortex and mamillo-thalamic tracts crucial for cognitive functioning were spared by electrode implantation. Additionally, with electrodes targeting the thalamus and adjacent subthalamic area, the actual electrical stimulation did not affect neuropsychological functioning. However, lesions caused by electrode implantation led to an increase in simple reaction time, while the actual electrical stimulation restored impaired reaction time. This is the second largest study of neuropsychological functioning in patients with ET treated with DBS, and the first covering a neuropsychological long-term follow-up over 6 years. Neither stereotactic surgery nor electrical stimulation affected higher cognitive processes. This study proposes that cerebello-thalamo-cortical pathways in humans are involved in tasks of simple reaction time.
Corporate strategies in maquila have changed over time. While they were originally geared only to the exploitation of low-paid, low-skilled labor, nowadays firms are upgrading human capital and increasing the scope and technological complexity of production processes. The adoption of the New Economic Model in host countries aimed precisely at this type of strategy change, but cannot solely be credited for it. In addition, policies regarding maquila under the NEM did not achieve all the stated goals regarding corporate strategy change: trends in local procurement and technology transfer are still unsatisfactory. Strengthening of local supply and absorption capabilities is required.
A facile preparation method was developed to obtain two-dimensional (2D) metal-free N, P-co-doped carbon nanosheets with sp2/sp3 interface derived from polymerizable ionic liquids (PIL) and ammonium nitrate (NH4NO3), exhibiting better electrocatalytic activity than that of the commercial Pt/C toward oxygen reduction reaction (ORR). The introduction of NH4NO3 can benefit the formation of carbon nanosheets structure and hierarchical porous structure due to decomposition and carbonization of polymer and gases emission resulting from ammonia nitrate, which can be confirmed by the SEM, TEM and BET results. The sp3 carbon and doping effect of heteroatoms of N, P can be investigated with the XPS, Raman and NEXAFS spectroscopy. The present work developed a facile method to prepare heteroatom-co-doped carbon as metal-free catalyst toward ORR with superior catalytic performance.
Uniform nanospherical Li2MnSiO4/C/graphene composites have been obtained by polyethylene glycol-600 (PEG-600) assisted solid-state reaction using spherical SiO2 as precursor, and heat treatment with the mixed carbon sources (glucose, cellulose acetate and graphene oxide). The transmission electron microscope (TEM) images show that Li2MnSiO4 nanospheres with size of 50 nm are embedded in the three-dimensional (3D) nest-like carbon network. Electrochemical measurements reveal that the composites exhibit first discharge capacity of 215.3 mAh g−1 under 0.05 C, together with a stable discharge capacity of 175 mAh g−1 after 40 cycles. The 3D carbon network and the carbon layer (amorphous carbon and graphene) are favorable for improving the electrochemical performance.
Solubilities of six lithium salts were measured at 25°C in three imidazolium-based ionic liquids: 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][Tf]) and 1-Butyl-3-methylimidazolium dicyanamide ([BMIM][DCA]). The lithium salts were LiTFSI, LiNO3, LiI, LiTf, LiPF6 and LiBF4. There were large differences in solubility of lithium salts depending on the anion of the salt and on the ionic liquid. The largest difference in solubility was observed for LiNO3. 7Li NMR spectra of the concentrated salt-containing ionic liquids indicate that Li+ and NO3 − are strongly associated in the investigated ionic liquids. The different abilities of the ionic liquids to solubilize these associated salts could explain the solubility differences. The ionic conductivity of each salt-containing ionic liquid was measured in the temperature range 15 to 60°C up to concentrations close to the solubility limit at 25°C. The ionic conductivity of the salt-containing ionic liquid decreases with salt concentration. Changing the lithium anion had almost no influence on the conductivity in [BMIM][[DCA] but a noticeable influence on the ionic conductivity in [EMIM][TFSI]. The solubilities in [EMIM][Tf] were too small to detect the effect of the anion of the lithium salt on conductivity.
A LiFePO4/C submicrofibers composite was prepared by a facile electrospinning method using LiNO3, Fe(NO3)3·9H2O, NH4H2PO4, citric acid and poly(4-vinyl)pyridine (PVP) as raw materials, and its physical properties and electrochemical performance were investigated by X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive analysis of X-ray (EDAX), N2 adsorption/desorption measurement and electrochemical tests. The crystal size of LiFePO4 fibers is about 30nm calculated by Debye-Scherrer equation and the LiFePO4 nanofibers aggregate to LiFePO4/C submicrofibers composite with diameters of about 270–372nm. The LiFePO4 submicrofibers are covered by an amorphous carbon layer with a thickness of about 2.6nm and the LiFePO4/C submicrofibers composite with mesopores exhibits amazing high surface area of 167.729m2 g−1. The LiFePO4/C submicrofibers composite displays high initial discharge capacities of 166 and 168mAhg−1 and excellent cycle performance at 0.1C (17mAhg−1) in the voltage range of 2.5–4.5V at 25 and 55°C, respectively. Even at high rate of 5C, the LiFePO4/C submicrofibers composite delivers discharge capacities of 132 and 138mAhg−1 and excellent cycle performance at 25 and 55°C, respectively. The results indicate that the electrospinning method is promising to prepare LiFePO4/C composite with high electrochemical performance.
Pure LiFePO4 was synthesized by heating an amorphous LiFePO4. The amorphous LiFePO4 obtained through lithiation of FePO4·xH2O by using oxalic acid as a novel reducing agent at room temperature. FePO4·xH2O was prepared through co-precipitation by employing FeSO4·7H2O and H3PO4 as raw materials. X-ray diffraction (XRD), scanning electron microscopy (SEM) observations showed that LiFePO4 composites with fine particle sizes between 100nm and 200nm, and with homogenous sizes distribution. The electrochemical performance of LiFePO4 powder synthesized at 500°C were evaluated using coin cells by galvanostatic charge/discharge. The synthesized LiFePO4 composites showed a high electrochemical capacity of 166mAhg−1 at the 0.1C rate, and possessed a favorable capacity cycling maintenance at the 0.1C, 0.2C, 0.5C and 1C rate.