Construction of BiOIO3/AgIO3 Z-Scheme Photocatalysts for the Efficient Removal of Persistent Organic Pollutants under Natural Sunlight Illumination.

The efficient removal of persistent organic pollutants (POPs) in natural waters is vital for human survival and sustainable development. Photocatalytic degradation is a feasible and cost-effective strategy to completely disintegrate POPs at room temperature. Herein, we develop a series of direct Z-scheme BiOIO3/AgIO3 hybrid photocatalysts via a facile deposition-precipitation method. Under natural sunlight irradiation, the light intensity of which is ∼40 mW/cm2, a considerable rate constant of 0.185 min-1 for photodecomposing 40 mg/L MO is obtained over 0.5 g/L Bi@Ag-5 composite photocatalyst powder, about 92.5 and 5.3 times higher than those of pristine AgIO3 and BiOIO3. The photoactivity of Bi@Ag-5 for photodecomposing MO under natural sunlight illumination surpasses most of the reported photocatalysts under Xe lamp illumination. After natural sunlight irradiation for 20 min, 95% of MO, 82% of phenol, 78% of 2,4-DCP, 54% of ofloxacin, and 88% of tetracycline hydrochloride can be photodecomposed over Bi@Ag-5. Relative to the commercial photocatalyst TiO2 (P25), Bi@Ag-5 exhibits greatly higher photoactivity for the treatment of MO-phenol-tetracycline hydrochloride mixture pollutants in the scale-up experiment of 500 mL of solution, decreasing COD, TOC, and chromaticity value by 52, 19, and 76%, respectively, after natural sunlight irradiation for 40 min. The photodegradation process and mechanism of MO have been systematically investigated and proposed. This work provides an archetype for designing efficient photocatalysts to remove POPs.

Physiological Signatures of Changes in Honeybee's Central Complex During Wing Flapping.

Many kinds of locomotion abilities of insects-including flight control, spatial orientation memory, position memory, angle information integration, and polarized light guidance are considered to be related to the central complex. However, evidence was still not sufficient to support those conclusions from the aspect of neural basis. For the locomotion form of wing flapping, little is known about the patterns of changes in brain activity of the central complex during movement. Here, we analyze the changes in honeybees' neuronal population firing activity of central complex and optic lobes with the perspectives of energy and nonlinear changes. Although the specific function of the central complex remains unknown, evidence suggests that its neural activities change remarkably during wing flapping and its delta rhythm is dominative. Together, our data reveal that the firing activity of some of the neuronal populations of the optic lobe shows reduction in complexity during wing flapping. Elucidating the brain activity changes during a flapping period of insects promotes our understanding of the neuro-mechanisms of insect locomotor control, thus can inspire the fine control of insect cyborgs.

Core-shell structured Z-scheme Ag2S/AgIO3 composites for photocatalytic organic pollutants degradation.

Constructing direct Z-scheme system is a promising strategy to boost the photocatalytic performance for pollution waters restoration, but it is of great challenge because of the requirement of appropriately staggered energy band alignment and intimate interfacial interaction between semiconductors. Herein, a class of core-shell structured Ag2S-AgIO3 Z-scheme heterostructure photocatalysts are designed and developed. Ag2S is generated by the in-situ ion exchange reaction and anchored on the surface of AgIO3, so the intimate interface between AgIO3 and Ag2S is realized. Integration of AgIO3 and Ag2S extends the ultraviolet absorption of AgIO3 to Vis-NIR region, and also promote the charge separation and migration efficiency, contributing to the enhanced photocatalysis activity for composite catalysts. The optimal Ag2S-AgIO4-4 catalyst exhibits a MO photo-degradation rate constant of 0.298 h-1, which reaches 5.77 and 11.4-folds higher than that of AgIO3 (0.044 h-1) and Ag2S (0.024 h-1). The as-obtained composite catalyst exhibits universally photocatalytic activity in disintegrating diverse industrial pollutants and pharmaceuticals. Particularly, driven by natural sunlight, the Ag2S-AgIO4-4 can effectively decompose MO. A plausible Z-scheme photocatalytic mechanism and reaction pathways of MO degradation over composite catalyst are systemically investigated and proposed.

Excitation of the abdominal ganglion affects the electrophysiological activity of indirect flight muscles of the honeybee Apis mellifera.

Our understanding of the nervous tissues that affect the wing flapping of insects mainly focuses on the brain, but wing flapping is a rhythmic movement related to the central pattern generator in the ventral nerve cord. To verify whether the neural activity of the abdominal ganglion of the honeybee (Apis mellifera) affects the flapping-wing flight, we profiled the response characteristics of indirect flight muscles to abdominal ganglion excitation. Strikingly, a change in the neural activity of ganglion 3 or ganglion 4 has a stronger effect on the electrophysiological activity of indirect flight muscles than that of ganglion 5. The electrophysiological activity of vertical indirect flight muscles is affected more by the change in neural activity of the abdominal ganglion than that of lateral indirect flight muscles. Moreover, the change in neural activity of the abdominal ganglion mainly causes the change in the muscular activity of indirect wing muscles, but the activity patterns change relatively little and there is little change in the complicated details. This work improves our understanding of the neuroregulatory mechanisms associated with the flapping-wing flight of honeybees.

Behavioral control and changes in brain activity of honeybee during flapping.

INTRODUCTION: Insect cyborg is a kind of novel robot based on insect-machine interface and principles of neurobiology. The key idea is to stimulate live insects by specific stimuli; thus, the flight trajectory of insects could be controlled as anticipated. However, the neuroregulatory mechanism of insect flight has not been elucidated completely at present. METHODS: To explore the neuro-mechanism of insect flight behaviors, a series of electrical stimulation was applied on the optic lobes of semi-constrained honeybees. Times of flight initiation, flapping frequency, and duration were recorded by a high-speed camera. In addition, flapping and steering initiation experiments of the cyborg honeybee were verified. Moreover, series of local field potential signals of optic lobes during flapping were collected, pre-processed to remove baseline wander and DC components, then analyzed by power spectrum estimation. RESULTS: A quantitative optimization method and optimal stimulation parameters of flight initiation were presented. Stimulation results showed that the flapping duration differed greatly while the flapping frequency varied with little difference among different individuals. Moreover, there was always a fluctuation peak around 20-30 Hz in power spectral density (PSD) curves during flapping, distinguishing from calm state, which indicated some brain activity changes during flapping. CONCLUSIONS: Our study presented a range of relatively optimal electrical parameters to initiate honeybee flight behavior. Meanwhile, the regularity of flapping duration and flapping frequency under electrical stimulations with different parameters were given. The feasibility of controlling a honeybee's flight behavior by brain electrical stimulation was verified through the flapping and steering initiation experiment of honeybees under semi-constrained state. PSD fluctuations reflected changes in brain activity during flapping and that those fluctuation characteristics at the specific frequency band could be sensitive determinants to distinguish whether the honeybee was flying or not, which benefits our understanding of honeybee's flapping behavior and furthers the study of honeybee cyborgs.