[Profile Distribution of Paddy Soil Organic Carbon and Its Influencing Factors in Chengdu Plain].

Understanding the effects of environmental factors on the profile distribution of soil organic carbon (SOC) is a base to accurately modeling the continuous change of SOC in vertical and three-dimensional spatial distributions, as well as precisely estimating SOC storage. Based on 171 soil profiles collected from Chengdu Plain, the effects of environmental factors (including the parent material, soil type, elevation, distance from river, and land use) on the profile distribution of paddy SOC to a depth of 1 m were evaluated through the exponential decay function. The results indicated that SOC was estimated at 19.42, 9.59, 5.99, and 5.20 g·kg-1 at depths of 0-20, 20-40, 40-60, and 60-100cm, respectively, showing a significant decrease with increased depth. Soil organic carbon was mainly concentrated above a 40 cm soil depth, accounting for 72.17% of the total profile, which could be crucial to studying the carbon source/sink of paddy soils in Chengdu Plain. The parameters of the exponential decay function had a similar spatial pattern, indicating their spatial dependence. The nugget coefficients for C and k were 55.400% and 47.671%, respectively, indicating that paddy SOC in the study area was affected by both structural and random factors. Regression analysis implied that the parent material and soil genius were the dominant factors influencing the profile distribution of SOC. Nevertheless, elevation, distance from river, and land use should also be taken into consideration. It has been concluded that the parent material and soil genius should be premeditated when fitting the vertical distribution of SOC, modeling the three-dimensional prediction of soil organic carbon, and estimating soil carbon storage in the paddy soils of Chengdu Plain.

Adsorption of Cd(II) from aqueous solutions by rape straw biochar derived from different modification processes.

In order to deal with cadmium (Cd(II)) pollution, three modified biochar materials: alkaline treatment of biochar (BC-NaOH), KMnO4 impregnation of biochar (BC-MnOx) and FeCl3 magnetic treatment of biochar (BC-FeOx), were investigated. Nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and scanning electron microscopy (SEM) were used to determine the characteristics of adsorbents and explore the main adsorption mechanism. The results show that manganese oxide particles are carried successfully within the biochar, contributing to micropore creation, boosting specific surface area and forming innersphere complexes with oxygen-containing groups, while also increasing the number of oxygen-containing groups. The adsorption sites created by the loaded manganese oxide, rather than specific surface areas, play the most important roles in cadmium adsorption. Batch adsorption experiments demonstrate a Langmuir model fit for Cd(II), and BC-MnOx provided the highest sorption capacity (81.10 mg g-1). The sorption kinetics of Cd(II) on adsorbents follows pseudo-second-order kinetics and the adsorption rate of the BC-MnOx material was the highest (14.46 g (mg·h)-1). Therefore, biochar modification methods involving KMnO4 impregnation may provide effective ways of enhancing Cd(II) removal from aqueous solutions.

Demonstration of low energy proton radiography on an 11-MeV cyclotron.

Lens focused proton radiograph on thin objects is demonstrated using an 11-MeV proton cyclotron at China Academy of Engineering Physics. The proton beam exiting from the tested objects is focused onto the image plane by a magnetic lens system mitigating image blur caused by multiple Coulomb scattering. Both simulations and experiments show that clear images can be obtained with a lens system for the objects with thickness up to 2.7 × 10-2 g/cm2 and the error for the areal density measurement is measured to be less than 2.3%. For the objects with thickness between 2.7 × 10-3 g/cm2 and 2.7 × 10-2 g/cm2, 100-200 µm of spatial resolution is achieved.

Automated, highly reproducible, wide-field, light-based cortical mapping method using a commercial stereo microscope and its applications.

We introduce a more flexible optogenetics-based mapping system attached on a stereo microscope, which offers automatic light stimulation to individual regions of interest in the cortex that expresses light-activated channelrhodopsin-2 in vivo. Combining simultaneous recording of electromyography from specific forelimb muscles, we demonstrate that this system offers much better efficiency and precision in mapping distinct domains for controlling limb muscles in the mouse motor cortex. Furthermore, the compact and modular design of the system also yields a simple and flexible implementation to different commercial stereo microscopes, and thus could be widely used among laboratories.

[Effect of Modified Biochars on Soil Cadmium Stabilization in Paddy Soil Suffered from Original or Exogenous Contamination].

To investigate the passivation of different modified biochars on the speciation and availability of cadmium contaminated soil, the modified biochars were treated by different approaches (acid/base treatment, impregnation with manganese oxides, magnetic modification) and biochars(BC) were used as soil passivating agents for soil culture experiments. The result indicated that the content of available cadmium decreased significantly by BC and modified biochars in originally contaminated soil. Compared with CK, the percentage of available cadmium in originally contaminated soil was reduced by more than 50% using impregnable biochars by KMnO4(BC-KMnO4) and basic biochars by NaOH(BC-NaOH). And the content of available cadmium decreased significantly by three modified biochars which were BC-KMnO4, BC-NaOH and FeCl3 magnetization biochars(BC-FeCl3) in exogenously contaminated soil. Particularly, the best performance was observed with BC-KMnO4 that reduced 30% available cadmium in exogenously contaminated soil. However, the passivation of BC was not significant, and the content of available cadmium slightly increased (3.8%-24.5%) by BC-HNO3 in exogenously contaminated soil. Furthermore, the content of exchangeable cadmium was increased by 20.2% with 2.5% BC-HNO3 in exogenously contaminated soil, while significantly decreased by other modified biochars and BC, and the 10% BC-KMnO4 reduced 65.1% exchangeable cadmium in originally contaminated soil. Meanwhile, soil pH was increased significantly by BC, BC-KMnO4 and BC-NaOH, while was reduced by BC-HNO3. The contents of organic carbon and exchangeable base cations in soil were improved by all the treatments. The results of regression analysis showed that the content of available cadmium in originally contaminated soil was significantly negatively correlated with soil pH, soil exchangeable Na+, while the content of available cadmium in exogenously contaminated soil was significantly negatively correlated with soil pH, soil organic carbon, soil exchangeable Mg2+, Na+, K+. Accordingly, the lower available cadmium in contaminated soil may correlate with the increasing content of organic carbon, exchangeable base cations and pH. In summary, the materials of BC-KMnO4 could be used as a superior passivating agent for in situ remediation of cadmium pollution, while the materials of BC-HNO3 could slightly activate cadmium in the soil, leading to some risk in in situ remediation.

Conditional deletion of Mecp2 in parvalbumin-expressing GABAergic cells results in the absence of critical period plasticity.

Mutations in the X-linked gene encoding the transcriptional modulator methyl-CpG-binding protein 2 (MeCP2) impair postnatal development of the brain. Here we use neuronal-type specific gene deletion in mice to show that conditional Mecp2 deletion in GABAergic parvalbumin-expressing (PV) cells (PV-Mecp2(-/y)) does not cause most Rett-syndrome-like behaviours, but completely abolishes experience-dependent critical period plasticity of primary visual cortex (V1) that develops normal visual functions. However, selective loss of Mecp2 in GABAergic somatostatin-expressing cells or glutamatergic pyramidal cells does not affect the critical period plasticity. MeCP2-deficient PV cells exhibit high intrinsic excitability, selectively reduced efficacy of recurrent excitatory synapses in V1 layer 4 circuits, and decreased evoked visual responses in vivo. Enhancing cortical gamma-aminobutyric acid (GABA) inhibition with diazepam infusion can restore critical period plasticity in both young and adult PV-Mecp2(-/y) mice. Thus, MeCP2 expression in inhibitory PV cells during the critical period is essential for local circuit functions underlying experience-dependent cortical plasticity.

Reevaluating the role of the hippocampus in delay eyeblink conditioning.

The role of the hippocampus in delay eyeblink conditioning (DEC) remains controversial. Here, we investigated the involvement of the hippocampus in DEC with a soft tone as the conditioned stimulus (CS) by using electrolytic lesions or muscimol inactivation of guinea pig dorsal hippocampus. Interestingly, when a soft tone was used as a CS, electrolytic lesions of the hippocampus significantly retarded acquisition of the conditioned response (CR), and muscimol infusions into hippocampus distinctly inhibited the acquisition and expression of CR, but had no significant effect on consolidation of well-learned CR. In contrast, both electrolytic lesions and muscimol inactivation of hippocampus produced no significant deficits in the CR when a loud tone was used as the CS. These results demonstrate that the hippocampus is essential for the DEC when the delay task was rendered more difficult.