Molecularly engineered organic copolymers as high capacity cathode materials for aqueous proton battery operating at sub-zero temperatures.

High-performance aqueous all-organic rechargeable batteries are promising candidates for cost-effective, safe, and environment-friendly next-generation energy storage devices. Herein, two organic copolymers with nanorod-like morphology (AN-TA, and AN-PA), composed of different tertiary amines, are synthesized as the cathode material for an aqueous proton battery. The individual copolymer electrodes possess the dominated diffusion-controlled electrode kinetics resulting from the proton insertion/de-insertion along with the surface-controlled processes in 2 M HCl and 2 M H2SO4. Among the two copolymers, AN-PA exhibits the maximum specific capacity of 145 mAh g-1 at 1 A g-1 and then, even at the higher current density of 10 A g-1, it possesses the capacity as 110 mAh g-1 in 2 M HCl. The assembled aqueous proton battery comprising of AN-PA as a cathode delivers the capacity of 80 mAh g-1 at 1 A g-1 in 2 M HCl. The maximum deliverable energy density of 33.9 Wh kg-1 is achieved at the power density of 423 W kg-1. Notably, our proton battery can well operate at the sub-zero temperature of -25 °C with a cell voltage of 1.1 V. More importantly, the device retains 84 % of the initial capacity after 1000 cycles at 2 A g-1 and exhibits the retention of specific capacity of about > 93% when compared to that of room temperature.

Reversible Association of Nitro Compounds with p-Nitrothiophenol Modified on Ag Nanoparticles/Graphene Oxide Nanocomposites through Plasmon Mediated Photochemical Reaction.

Because localized surface plasmon resonance in nanostructures of noble metals is accompanied by interesting physical effects such as optical near-field enhancement, heat release, and the generation of hot electrons, it has been employed in a wide range of applications, including plasmon-assisted chemical reactions. Here, we use a composite of silver nanoparticles and graphene oxide (Ag@GO) as the catalytic as well as the analytic platform for plasmon-assisted chemical reactions. Through time-dependent surface-enhanced Raman scattering experiments, it is found that p-nitrothiophenol (pNTP) molecules on Ag@GO can be associated with nitro compounds such as nitrobenzene and 1-nitropropane to form azo compounds when aided by the plasmons. Furthermore, the reaction rate can be modulated by varying the wavelength and power of the excitation laser as well as the nitro compounds used. In addition, the aforementioned coupling reaction can be reversed. We demonstrate that the oxidation of azo compounds on Ag@GO using KMnO4 leads to the dissociation of the N═N double bond in the azo compounds and that the rate of bond dissociation can be accelerated significantly via laser irradiation. Furthermore, the pNTP molecules on Ag@GO can be recovered after the oxidation reaction. Finally, we demonstrate that the plasmon-assisted coupling reaction allows for the immobilization of nitro-group-containing fluorophores at specific locations on Ag@GO.

Temporary anion states of p-benzoquinone: shape and core-excited resonances.

The studies of shape and core-excited resonances are essential in the bonding and electronic processes of quinones. So far, the experimental results of temporary anion states for p-benzoquinone cannot be fully ascertained computationally. In this paper, both resonances of p-benzoquinone are investigated via the stabilization method (SM). For shape resonances, the stabilized Koopmans theorem is adopted in the framework of long range corrected density functional theory (LC-DFT). As for core-excited resonances, the SM coupled with long range corrected time-dependent density functional theory (LC-TDDFT) is employed. The resonance energies and lifetimes are then estimated via an analytic continuation procedure in conjunction with the stabilization plots. Using this novel combination, previous experimental results of temporary anion states can be successfully identified. It is believed that this novel approach can be an accurate and efficient methodology in the study of temporary anion states of quinones.

Energies and lifetimes of temporary anion states of chloromethanes by stabilized Koopmans' theorem in long-range corrected density functional theory.

To investigate the resonance energies and lifetimes of temporary anion states of chloromethanes, long-range corrected density functional theory is adopted in this article. Their values are determined by calculating the density of resonance states via the stabilized Koopmans' theorem. The characteristics of these resonance orbitals are also analyzed. By comparing with experimental values and previous theoretical calculations, our method can yield not only conformable results but also more complete information on the resonance states.

Characterization of the temporary anion states on perfluoroalkanes via stabilized Koopmans' theorem in long-range corrected density functional theory.

The stabilized Koopmans' theorem (SKT) in long-range corrected density functional theory is used to characterize the temporary anion states of perfluoro-n-alkanes (n-PFAs) from C(2) to C(5), and perfluorocycloalkanes (c-PFAs) from C(3) to C(4). In this approach, stabilization is accomplished by varying the exponents of appropriate diffuse functions. The energies of temporary anion states are then identified by investigating the relationship between the resultant eigenvalues and scale parameter. The characteristics of resonance orbitals are also examined. For the lowest unfilled orbitals of perfluoroalkanes, results indicate that they are mainly from the π-bonding interactions between all neighboring C atoms. In addition, their energies decrease as the sizes of the perfluoroalkanes increase. Moreover, the energies of the c-C(3)F(6)/c-C(4)F(8) are lower than those of the corresponding n-C(3)F(8)/n-C(4)F(10). When compared with experimental data, our SKT calculations can yield conformable results. Thus, this SKT approach can provide more information on the resonance states of perfluoroalkanes.

Energy and lifetime of temporary anion states of uracil by stabilization method.

To investigate the temporary anion states of uracil, density functional theory with asymptotically corrected potentials is adopted. The stabilized Koopmans' theorem and stabilized Koopmans-based approximation are used in conjunction with an analytic continuation procedure to calculate its resonance energies and lifetimes. Results indicate the presence of several low-lying π* and σ* temporary anion states of uracil. The characteristics of these resonance orbitals are also analyzed. By comparing them with the experimental values and theoretical calculations, it is believed that the stabilization approach can provide more information on the resonance states.

Application of the stabilization method to temporary anion states of CH3CN, CH3NC, CH3SCN, and CH3NCS in density functional theory with asymptotically corrected potentials.

In this paper, density functional theory (DFT) with asymptotically corrected potentials is used to investigate CH(3)CN, CH(3)NC, CH(3)SCN, and CH(3)NCS molecules. For the energies of σ* and π* temporary anion states, the stabilized Koopmans' theorem (S-KT) using long-range correction functional and stabilized Koopmans-based (S-KB) approximation using local functional, are adopted. The stabilization procedure is accomplished by varying the exponents of appropriate diffuse functions. Results indicate that the calculations based on asymptotically corrected density functionals can yield better energy results of temporary anion states over conventional DFT methods.

Application of the stabilization method to temporary anion states of pi-ligand transition-metal carbonyls in density functional theory.

In this paper, density functional theory is used to investigate (benzene)chromium tricarbonyl, (cyclopentadienyl)manganese tricarbonyl, (1,3-butadiene)iron tricarbonyl, and (cyclopentadienyl)cobalt dicarbonyl. For the energies of low-lying temporary anion states, the stabilized Koopmans-based (S-KB) and stabilized Koopmans theorem (S-KT) methods are adopted. Stabilization is accomplished by varying the exponents of appropriate diffuse functions. Results indicate that the calculations of S-KB using PBEPBE and S-KT using CAM-B3LYP are able to yield energies of temporary anion states in good agreement with the experimental values. Furthermore, the ionization potentials can be determined accurately via the Koopmans-based (KB) PBEPBE method.

The cooperative phenomenon of autonomic nervous system in urine storage for Wistar rats.

The fractal dimension (FD) and spectral frequencies of physiological signals are two important indices in the study of physiological functions and dynamical diseases. The first index can be used to characterize the intensity and the second the rhythms of signals embedded in seemingly random data. Recent studies using both indices verified that synergic co-activations of bladder and external urethral sphincter (EUS) of Wistar rats were present during the voiding of urine. In this study, the primary aims were to (1) examine if the involved muscles in the lower urinary tract would be under similar coactivations during the urine storage phase, and (2) characterize quantitatively the sympathetic and parasympathetic nerve activities simultaneously. Eighteen experiments were performed on six intact adult female Wistar rats and then the electromyogram of EUS and cystometrogram of bladder were analyzed. Results indicated that the EUS did not contain any significant spectral frequencies in the storage phase. Furthermore, its FDs (1.5918 +/- 0.0157) indicated that no appreciable amount of signal intensities was observed in the EUS. On the other hand, the bladder exhibited parasympathetic frequency of 8 Hz with signal-to-noise ratio (SNR) = 19.9001 decibel (dB) for group mean, and sympathetic frequency of 19 Hz with SNR = 22.8330 dB for group mean. In addition, its FDs (1.4796 +/- 0.0092) indicated relatively persistent intensities during storage, as compared to that of EUS (1.5918 +/- 0.0157) with statistical significance (P < 0.01). We concluded that the EUS was not activated during the phase of storage. The bladder was under the cooperative, not antagonistic, sympathetic and parasympathetic nerve activities with discernible rhythmic frequencies and persistent intensities.

Dynamic performance evaluation on the synergy of micturition in spinal cord-injured female rats under pharmacological effects.

Recently, a temporal "coherent" fractal structure and synchronization of rhythms were proposed as two essential indicators for efficient voiding during micturition in female rats. The former was correlated with the intensity and the latter the frequency of physiological signals embedded in random noise. Studies using both indices confirmed that synergic co-activations of bladder and external urethral sphincter (EUS) of female rats were present during the voiding of urine. Therefore, it would be interesting to investigate if these two criteria could be used in the performance evaluation of pharmacological effects on spinal cord-injured rats during micturition. In this paper, the primary goals were to (1) examine if the involved muscles in the lower urinary tract would be under similar synergic co-activations during the administration of capsaicin (CAP) and resiniferatoxin (RTX), and (2) characterize quantitatively the differences of their nervous responses simultaneously. A total of 62 micturition experiments were performed on sixteen spinal cord-injured adult female Sprague-Dawley rats, and then the electromyograms of EUS and cystometrograms of bladder were analyzed. Results based on the aforementioned criteria indicated that the synergy of bladder and EUS during micturition by using RTX was better than that of the CAP. Furthermore, the residue urine volumes for rats under the former treatment were smaller than those of the rats under the latter treatment. Consequently, we concluded that the administration of RTX was more effective than CAP in facilitating voiding in the spinal cord-injured rats.

Effects of acupuncture at Neiguan (PC 6) on electroencephalogram.

The aim of this study was to investigate if there were any effects on the electroencephalogram (EEG) of human brain by the manual stimulation of Neiguan (PC 6) acupuncture site. In this paper, two groups of six healthy male volunteers of ages 27.6 +/- 14.2 (mean +/- SD) and 28.5 +/- 13.0 (mean +/- SD) and no neurological disease participated in this study. A digital storage of 12-channel EEG recorder was used and spectral analyses of the data set of 18 trials were obtained before, during, and after sham/ manual acupuncture. To minimize artefacts, all data were collected with the subjects alert but eyes closed. No significant changes (P > 0.05) were obtained for the sham acupuncture group. As for the manual acupuncture group, the needle was inserted perpendicularly into the PC 6 acupuncture site and manually stimulated about 15 to 30 seconds to achieve De Qi sensation. Needles were left in place for 30 min and then removed. Analysis of the EEG data due to acupuncture was compared to the baseline data and changes were obtained. First, all trials had an increase in the amplitude and power of the alpha band during manual acupuncture (P < 0.05) when compared with the baseline data. Secondly, in the mean time, the frequency peaks in alpha band of 12-channels were all synchronized with much smaller standard deviation (P < 0.01). Thirdly, the manual acupuncture effects of higher power and synchronized frequencies persisted for at least 10 minutes after the experiment (P < 0.05) and did not disappear immediately for all 18 experiments. Finally, we hypothesized that the higher power and synchronized rhythms in brain oscillations may have to do with autonomic nervous system.

Temporary anion states of ferrocene and dibenzene chromium using stabilization method in density functional theory.

The Koopmans-based (KB) approximation is used to investigate the ionization potentials of ferrocene and dibenzene chromium in density functional theory. As to the energies of low-lying temporary anion states of these transition metal complexes, the stabilization method coupled with KB approximation (S-KB) is adopted. Here, the stabilization is accomplished by varying the exponents of appropriate diffuse functions. Results indicate that the S-KB method is much more successful than other methods in predicting absolute and relative energies of temporary anion states. Furthermore, the ionization potentials via KB approach are very close to the experimental values.

Application of the stabilization method to the pi* temporary anion states of benzene and substituted benzenes in density functional theory.

The stabilization method is used in conjunction with Koopmans-based approximation to calculate the energies of pi* temporary anion states of a series of substituted benzenes in density functional theory. In this approach, the Koopmans expression is corrected due to the consideration of the integer discontinuities in the exact exchange-correlation potential. Stabilization is accomplished by varying the exponents of appropriate diffuse functions. The energies of pi* states are then identified by investigating the relationship between the resultant eigenvalues and scale parameter. Results indicate that this approach can yield an improvement in the predictions of the absolute energies of pi* states over other methods.

Effects of acupuncture at Neiguan (PC 6) of the pericardial meridian on blood pressure and heart rate variability.

The aims of this study were to investigate (i) if and when the blood pressure would rise or fall and (ii) the associated changes of human heart rate variability (HRV) by manual stimulation of the Neiguan (PC 6) acupuncture site. In this paper, two groups of six healthy male volunteers with ranges of ages 20-56 and 20-55 and with no neurological diseases participated in this study. In order to minimize artefacts, the electrocardiogram (ECG) and radial arterial pulse pressure wave were collected with the subjects alert but eyes closed before, during, and after sham/manual acupuncture. No statistically significant changes (P > 0.05) were found in the sham acupuncture group. As for the manual acupuncture group, the needle was inserted into the PC 6 acupoint and manually stimulated about 15 to 30 seconds to achieve De Qi sensation. Needles were left in place for 30 min and then removed. Analysis of the data due to acupuncture was then compared with the baseline values. Results indicate that the blood pressures of different subject can either rise (P < 0.01) or fall (P < 0.01). To further determine the indicator for one subject who exhibited both rise and fall of blood pressures, 7 more trials were given conducted with the same protocol until statistically significant results were obtained (P < 0.01). We found that his change of blood pressure was highly correlated (p = -0.94 and -0.99 for rise and fall, respectively) with the ratio of the magnitude of pulse pressure to that of the dicrotic notch in the local radial pulse wave (P < 0.01). As to the heart rate variability (HRV) spectra, significant changes in the low frequency (LF) and very low frequency (VLF) ranges were also detected. These results indicate that the autonomic innervations of heart have been modified. However, the information on the power of LF, high frequency (HF), and LF/HF of HRV are not conclusive to statistically differentiate the sympathetic contribution from that of the parasympathetic nervous systems at present stage.

Synergic co-activation in forearm pronation.

Co-activations of agonist and antagonist muscles are believed to be present in voluntary limb movement. Recent studies indicate that such co-activations are either synergic or dyssynergic. The aims of this paper are to (1) develop a novel method that can extract both the intensity and frequency information from the recordings of the surface electromyograms (EMGs) of involved muscles, and (2) investigate if the involved muscles will be under synergic co-activation during voluntary forearm pronation for normal subjects and dyssynergic co-activation for patients with radial nerve palsy. We examined 11 healthy subjects and 4 patients with right-arm radial nerve palsy in this study. For the group of healthy subjects, each one of them was asked to perform 30 trials of voluntary forearm pronation and then 30 trials of passive pronation as control experiments. As to the second group of patients, each one was asked to perform only 15 trials of voluntary pronation due to the limitation and durability of their arms. The recordings of the surface EMGs included the short and long heads of the biceps brachii, the brachialis, the lateral head of the triceps brachii, brachioradialis, and pronator teres. Experimental results of the healthy group indicated that the surface EMGs of all muscles had no statistically significant changes in fractal dimensions (FDs) and spectral frequencies of the control experiments during passive pronation. Yet, during the voluntary pronation experiments, the surface EMGs of all muscle groups were temporally synchronized in frequencies with persistent intensities. Hence, all involved muscle groups were in synergic co-activation. Statistical results of the group mean values of FDs during rest vs. forearm pronation also revealed significant difference with p < 0.01 for healthy subjects. As to the group of patients, their EMGs could still have bursting activities, but the synchronized significant frequencies might be lacking or the intensities as indicated from their FDs would not be persistent. To further compare the FDs among the three different protocols, a mixed-model ANOVA and multiple comparison tests were performed. Finally, in order to illustrate the advantages of this novel method, we have compared it with the detrended fluctuation analysis (DFA). It is believed that this proposed method will have the potential to be a biomarker for evaluating dynamical disease in neuromuscular disorders.

Synergic co-activation of muscles in elbow flexion via fractional Brownian motion.

In reflex and volitional actions, co-activations of agonist and antagonist muscles are believed to be present. Recent studies indicate that such co-activations can be either synergic or dyssynergic. The aim of this paper is to investigate if the co-activations of biceps brachii, brachialis, and triceps brachii during volitional elbow flexion are in the synergic or dyssynergic state. In this study, two groups with each containing six healthy male volunteers participated. Each person of the first group performed 30 trials of volitional elbow flexion while each of the second group performed 30 trials of passive elbow flexion as control experiments. Based on the model of fractional Brownian motion, the intensity and frequency information of the surface electromyograms (EMGs) could be extracted simultaneously. No statistically significant changes were found in the control group. As to the other group, results indicated that the surface EMGs of all five muscle groups were temporally synchronized in frequencies with persistent intensities during each elbow flexion. In addition, the mean values of fractal dimensions for rest and volitional flexion states revealed significant differences with P < 0.01. The obtained positive results suggest that these muscle groups work together synergically to facilitate elbow flexion during the co-activations.