A micro-porous network thin film of core-tetrachlorinated perylene bisimide (PBI) was deposited by electrochemical polymerization, which showed reversible n-doping/dedoping processes at rather low potentials, accompanied by color changes from an orange red (neutral) state to a transparent (radical anion) state and further to an aquamarine (dianion) state. The film possesses preferable coloration efficiency and cycling stability (>10 000 cycles).

A redox active polymer network film containing donor–node–acceptor (D–n–A) units was prepared by using the electropolymerization (EP) of the precursor (4Cz–4Cl–PBI). The polymer film was characterized by the UV–vis absorption, FT-IR, SEM, XRD and electrochemical techniques. The precursor contains phenyl connected two carbazoles (D) linked by the two sp3 N-nodes on both sides of a tetrachloro-substituted PBI (A). The two N-nodes block the conjugation between D and A units, resulting in an independent redox activity (from D and A) and doping behaviors. This novel concept of the D–n–A polymer effectively increases the conductivity and stability of the n-doped state. The EP film can be prepared on ITO and flexible electrodes with large area, smooth surface morphology, controllable thickness, and nanoporous structure. Notably, the polymer network film showed ambipolar doping characteristics, with high capacitance (both n- and p-doped states). These properties are very suitable to construct ambipolar electrodes for the flexible supercapacitors. The flexible solid-state supercapacitor devices made from poly­(4Cz–4Cl–PBI) network film can readily charge and discharge (fast electron transfer). The flexible supercapacitor showed a very large potential window (2.2 V) and high power density (17.4 W cm–3).

Dear Editor:Whether or not acupuncture intervention involves neurologic effects has recently been explored via functional magnetic resonance imaging (fMRI) experiments commonly consisting of multiple experimental blocks with ON-and OFF-condition alternations. Such fMRI experiments normally employed a block interval of more than a minute. 1-3 However, the psychophysical response to acupuncture, a needling (or de qi) sensation (a sensation including sourness, numbness, heaviness, and distension surrounding the area of needle insertion), introduced by the acupuncture stimulus conducted in one current trial can be carried over to the next trial. This carryover effect might alter the baseline condition of the following trials and thus affect data analyses, possibly resulting in incongruent conclusions. Here, we demonstrate the carryover effect with a psychophysical test using a single block of acupuncture needling. 4 Subjective psychophysical responses were obtained from 16 subjects (6 females and 10 males, 27 Ϯ 2.7 years old). The subjects received acupuncture at the acupoint of left ST42 (Chong Yang). In this experiment, the needle was inserted and twisted clockwise and counterclockwise at a frequency of 1-2 Hz to produce a needling sensation. The subjects were requested to continually report this needling sensation verbally every 10 seconds, for up to 1 hour. The needling sensation was scored from 0 (no de qi at all) to 10 (the strongest de qi sensation a subject can endure).The result showed that the initial de qi was the strongest reaction, which then reached its plateau at 20 seconds and started to drop at 2 minutes (Fig. 1). This strongly suggests that if the block duration is less than 2 minutes in a multiblock fMRI experiment, the evoked brain responses registered to the current acupuncture stimulus would be prolonged enough to perturb the baseline of the subsequent trial(s). This can further affect the ON/OFF contrasting in the statistical analysis. In other words, a multiblock design with its OFF-condition lasting longer than 2 minutes for each block or a single-block design will be more suitable for conducting an fMRI acupuncture study. In the future, we will demonstrate empirically the influence of carryover effects on an fMRI study involving acupuncture stimulation with a larger sample size and compare the result from multiple-and single-block experimental designs. REFERENCES1. Cho ZH, Chung SC, Jones JP, et al. New findings of the correlation between acupuncture points and corresponding brain cortices using functional MRI. Proc Natl Acad Sci U S A 1998;95:2670-2673. 2. Cho ZH, Oleson TD, Alimi D, Niemtzow RC. Acupuncture:The search for biologic evidence with functional magnetic resonance imaging and positron emission tomography techniques.

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In bulk-heterojunction-based organic photovoltaics, strong light-absorbing ability is one of the most important advantages of nonfullerene acceptors prior to fullerene derivatives. Herein, a series of electron-donating units was asymmetrically connected at the imide positions of perylene diimide (PDI), which is a classic-electron acceptor building block. The photoinduced electron-transfer behaviors were compared in different substitutions by steady/time-resolved spectroscopy and theoretical simulation. The electron-donating ability as well as the donor–acceptor distance has a significant impact on the photoinduced electron transition from electron-donating units to the PDI core. Because of the process of charge transfer at excited states, a fast nonradiative deactivation is observed for the PDIs with relatively strong electron substituent. These results would help us to understand the electron-transfer processes from donor to acceptor in the case of the excited electron-acceptor molecule.