Linking chemical structure of dissolved organic carbon and microbial community composition with submergence-induced soil organic carbon mineralization.

Much research has been devoted to investigating how water-extractable organic carbon (DOC) concentration and microbial activity regulate soil organic carbon (SOC) mineralization when soils are saturated with water. However, the relationships of DOC chemical structure and microbial community composition with SOC mineralization, as well as the relative contributions of microbial decomposers and their substrates on the mineralization rate have rarely been examined. In a laboratory experiment, we incubated two typical cropland soils (an Entisol and a Mollisol) of China for 360 days under submerged and non-submerged conditions, and we evaluated the concentration and chemical structure of soil DOC, soil microbial metabolic potential and community composition by using total C/N analysis, solution-state 1H NMR, Biolog EcoPlates, and 16S rRNA amplicon sequencing, respectively. The results showed that submergence significantly increased DOC concentration (P < 0.01) and microbial activity (P < 0.001) and changed DOC chemical structure in the Entisol (P < 0.01). In the Mollisol, it significantly increased the rate (P < 0.01) and cumulative extent (P < 0.001) of SOC mineralization and DOC concentration (P < 0.01) as well as altering the composition of the microbial community (P < 0.001). Moreover, the SOC mineralization rate was better explained by microbial community composition (Entisol: SPC = -0.71, P < 0.001; Mollisol: SPC = 0.92, P < 0.001) than by DOC concentration (Entisol: SPC = 0.21, P > 0.05; Mollisol: SPC = 0.30, P < 0.05) or DOC chemical structure (Entisol: SPC = 0.12, P > 0.05; Mollisol: SPC = -0.45, P < 0.001). Our study revealed that the bacterial community composition had a close relationship to the rate of submergence-induced SOC mineralization in both soils, but only DOC concentration and chemical structure were effective predictors of mineralization rate in the low-pH Mollisol.

Computer-assisted needle trajectory planning and mathematical modeling for liver tumor thermal ablation: A review.

Radiofrequency ablation (RFA) and microwave ablation (MWA) have become an important means for treating liver tumors. RFA and MWA are a minimally invasive therapy which involves an ablation applicator or needle (i.e., radiofrequency electrode or microwave antenna) inserted percutaneously into a tumor under the guidance of medical imaging, so as to destroy the tumor in situ by heating-induced coagulation necrosis. Treatment planning, particularly needle trajectory planning, is crucial to RFA and MWA. In clinical procedures, however, needle trajectory planning still relies on the personal experience of clinicians. Manual needle trajectory planning is tedious and may cause inter-operator difference. Therefore, computer-assisted needle trajectory planning techniques are of clinical value and have been extensively explored. However, a literature review that focuses on computer-assisted needle trajectory planning for liver tumor RFA and MWA has not been reported. In this paper, we conducted an extensive review on computer-assisted needle trajectory planning for RFA and MWA of liver tumors. Fundamentals of needle trajectory planning are summarized. Algorithms for single-needle and multi-needle trajectory planning are analyzed. Shortcomings of current computer-assisted needle trajectory planning algorithms are discussed and future developments are suggested.

Numerical evaluation of ablation zone under different tip temperatures during radiofrequency ablation.

The present study aimed at investigating the relationship between the shape and size of ablation zone and the ablation time during radiofrequency ablation (RFA) at different tip temperatures (80, 85, 90, and 95 °C). A two-dimensional simulation model of liver RFA using single-electrode was first built by finite element method (FEM). A closed-loop proportional-integral (PI) controller was employed in the FEM model. The heat transfer issues were solved based on Pennes biological equation. To improve simulation accuracy of the FEM models, temperature-dependent forms of the electrical conductivity and the thermal conductivity were adopted in the model. The ablation zone was assessed by 54 °C isothermal contour (IT54). The ablation zone sizes obtained from the numerical simulations and ex vivo experiments were compared to evaluate the validity of the numerical model. All the four tip temperatures (80, 85, 90, and 95 °C) were tested using 3 ex vivo porcine livers respectively. According to numerical simulation results, the characterization functions of the ablation volume and the ablative margin (AM) were derived. The proposed curve functions could precisely characterize the shape and size of ablation zone at different preset tip values, and the statistical results showed that the prediction curves had a good consistency with simulation curves. This paper proposed the prediction models of the ablation zone in the RFA process, which could be used to achieve accurate planning of RFA needle placements and optimize patient care during temperature-controlled RFA therapy.

Biochemical stabilization of soil organic matter in straw-amended, anaerobic and aerobic soils.

Crop straw incorporation is a useful approach for increasing the quantity and changing the chemical composition of soil organic matter (SOM). This process is influenced by soil aeration. The present study investigated the stability of whole SOM, particulate organic matter (POM) and mineral-associated organic matter (MinOM) fractions with wheat straw amendment under aerobic and anaerobic conditions over a 12-month incubation period. Solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to analyze the chemical composition of whole SOM, POM and MinOM fractions. The decomposition rate of wheat straw was lower under anaerobic than under aerobic conditions (0.014 vs. 0.020day-1). Wheat straw incorporation increased the original soil organic carbon content (7.4g kg-1) under both aerobic (up to 10.2g·kg-1) and anaerobic (up to 10.3g·kg-1) conditions, but the content of mineral-associated organic carbon (MinOC) under aerobic condition (7.0g·kg-1) was significantly larger than that under anaerobic condition (4.9g·kg-1). The proportion of alkyl carbon (C) in SOM, POM and MinOM fractions was greater under anaerobic than under aerobic conditions, while the opposite was true for the proportion of O-alkyl C of SOM and POM and MinOM fractions. A/O-A indices (i.e., the ratio of alkyl C to O-alkyl C) of whole SOM, POM and MinOM were higher under anaerobic than under aerobic conditions. We conclude that wheat straw incorporation resulted in the enrichment of alkyl C in the POM and MinOM fractions under anaerobic conditions, and thus improved the stability of SOM. In this way, the decomposition of crop residue influenced SOM structural chemistry at the molecular level.

Al(3+) -promoted fluoride accumulation in tea plants (Camellia sinensis) was inhibited by an anion channel inhibitor DIDS.

BACKGROUND: Generally, tea plants are grown in acid soil which is rich in aluminum (Al) and fluoride (F). A recent publication showed that pretreatment with Al(3+) promoted F accumulation in tea plants by increasing endogenous Ca(2+) and calmodulin (CaM). A high level of F in tea leaves not only impairs tea quality but also might pose a health risk for people drinking tea regularly. Therefore it is important to try to find some clues which might be beneficial in controlling F accumulation in tea plants grown in acid soil (Al(3+) ). RESULTS: It was found that diisothiocyanostilbene-2,2-disulfonic acid (DIDS) significantly reduced Al(3+) -promoted F accumulation in tea plants. Additionally, Al(3+) plus DIDS treatment stimulated significantly higher Ca(2+) efflux and decreased the CaM level in tea roots compared with Al(3+) treatment. Besides, significantly higher depolarization of membrane potential was shown in tea roots treated with Al(3+) plus DIDS than in those treated with Al(3+) , as well as higher net total H(+) efflux and plasma membrane H(+) -ATPase activity. CONCLUSION: Al(3+) -promoted F accumulation in tea plants was inhibited by an anion channel inhibitor DIDS. Ca(2+) /CaM and membrane potential depolarization may be the components involved in this process. © 2016 Society of Chemical Industry.

Anion Channel Inhibitor NPPB-Inhibited Fluoride Accumulation in Tea Plant (Camellia sinensis) Is Related to the Regulation of Ca²âº, CaM and Depolarization of Plasma Membrane Potential.

Tea plant is known to be a hyper-accumulator of fluoride (F). Over-intake of F has been shown to have adverse effects on human health, e.g., dental fluorosis. Thus, understanding the mechanisms fluoride accumulation and developing potential approaches to decrease F uptake in tea plants might be beneficial for human health. In the present study, we found that pretreatment with the anion channel inhibitor NPPB reduced F accumulation in tea plants. Simultaneously, we observed that NPPB triggered Ca(2+) efflux from mature zone of tea root and significantly increased relative CaM in tea roots. Besides, pretreatment with the Ca(2+) chelator (EGTA) and CaM antagonists (CPZ and TFP) suppressed NPPB-elevated cytosolic Ca(2+) fluorescence intensity and CaM concentration in tea roots, respectively. Interestingly, NPPB-inhibited F accumulation was found to be significantly alleviated in tea plants pretreated with either Ca(2+) chelator (EGTA) or CaM antagonists (CPZ and TFP). In addition, NPPB significantly depolarized membrane potential transiently and we argue that the net Ca(2+) and H⁺ efflux across the plasma membrane contributed to the restoration of membrane potential. Overall, our results suggest that regulation of Ca(2+)-CaM and plasma membrane potential depolarization are involved in NPPB-inhibited F accumulation in tea plants.

[Physical and chemical maturity indexes and Fourier transform infrared (FTIR)spectroscopy of animal manures during composting.] / ç•œç¦½ç²ªä¾¿å †è‚¥çš„ç†åŒ–è ç†ŸæŒ‡æ ‡åŠå ¶çº¢å¤–å ‰è°±.

The composting experiments on three manures (cattle, pig and chicken manures) were carried out to study the maturity indexes by monitoring their physical and chemical properties, seed germination index (GI), and characterizing chemical structures using Fourier transform infrared (FTIR) spectroscopy. Results showed that temperature changed during composting, and the numbers of peak temperatures for cattle, chicken, and pig manures were 1, 2 and 2, respectively. The duration with temperature higher than 50 ℃ was longer than 10 days for all the three manures. This indicated that temperature was the most intuitive maturity index. The pH of pig and chicken manures increased from 6.63 to 7.74 and from 7.73 to 8.66, respectively, while that of cattle manure first increased from 7.86 to 8.36 and then decreased to 7.52. The organic carbon content decreased by23.3%, 28.2%, and 31.7%, respectively, for cattle, pig and chicken manures. In addition, the NH4+-N concentrations decreased by 87.8%, 73.6%, and 79.7%, and the NO3--N increased by 56.81, 6.49, and 4.85 times for cattle, pig, and chicken manures, respectively. The ratio of NH4+-N/NO3--N of piles decreased below 2. Our study indicated that temperature, pH, organic carbon content, and ratio of NH4+-N/NO3--N were closely related to maturity index and correlated with seed germination rate (P≤0.05). The FIIR spectra revealed that in the cattle and pig manures aliphatic compounds and polysaccharides decreased but aromatics increased during the process of composting, suggesting enhanced humification. However, the trend was reversed for chicken manure. Therefore, it was necessary to take into account the stability of composts while maturity indexes were sought.

Ca(2+) and CaM are involved in Al(3+) pretreatment-promoted fluoride accumulation in tea plants (Camellia sinesis L.).

Tea plant (Camellia sinensis (L.) O. kuntze) is known to be a fluoride (F) and aluminum (Al(3+)) hyper-accumulator. Previous study showed that pre-treatment of Al(3+) caused a significant increase of F accumulation in tea plants. However, less is known about the intricate network of Al(3+) promoted F accumulation in tea plants. In this study, the involvement of endogenous Ca(2+) and CaM in Al(3+) pretreatment-promoted F accumulation in tea plants was investigated. Our results showed that Al(3+) induced the inverse change of intracellular Ca(2+) fluorescence intensity and stimulated Ca(2+) trans-membrane transport in the mature zone of tea root. Also, a link between internal Ca(2+) and CaM was found in tea roots under the presence of Al(3+). In order to investigate whether Ca(2+) and CaM were related to F accumulation promoted by Al(3+) pretreatment, Ca(2+) chelator EGTA and CaM antagonists CPZ and TFP were used. EGTA, CPZ, and TFP pretreatment inhibited Al(3+)-induced increase of Ca(2+) fluorescence intensity and CaM content in tea roots, and also significantly reduced Al(3+)-promoted F accumulation in tea plants. Taken together, our results suggested that the endogenous Ca(2+) and CaM are involved in Al(3+) pretreatment-promoted F accumulation in tea roots.

Localization of fluoride and aluminum in subcellular fractions of tea leaves and roots.

The tea plant is a fluoride (F) and aluminum (Al) hyperaccumulator. High concentrations of F and Al have always been found in tea leaves without symptoms of toxicity, which may be related to the special localization of F and Al in tea leaves. In this study, we for the first time determined the subcellular localization of F and Al in tea roots and leaves and provided evidence of the detoxification mechanisms of high concentrations of F and Al in tea plants. Results revealed that 52.3 and 71.8% of the total F accumulated in the soluble fraction of tea roots and leaves, and vacuoles contained 98.1% of the total F measured in the protoplasts of tea leaves. Cell walls contained 69.8 and 75.2% of the total Al detected in the tea roots and leaves, respectively, and 73.2% of Al sequestered in cell walls was immobilized by pectin and hemicellulose components. Meanwhile, 88.3% of the Al measured in protoplasts was stored in the vacuoles of tea leaves. Our results suggested that the subcellular distributions of F and Al in tea plants play two important roles in the detoxification of F and Al toxicities. First, most of the F and Al was sequestered in the vacuole fractions in tea leaves, which could reduce their toxicities to organelles. Second, Al can be immobilized in the pectin and hemicellulose components of cell walls, which could suppress the uptake of Al by tea roots.

Exercise ameliorates the detrimental effect of chloroquine on skeletal muscles in mice via restoring autophagy flux.

AIM: To study the roles of autophagy in muscle establishment during long-term exercise in mice. METHODS: Female ICR mice were submitted to exercise training with a wheel running regimen: 6 m/min, 15 min/time, 3 times/d (on 8:00, 14:00, and 20:00), 5 d/week for 2 months. The mice were treated with the autophagy activator trehalose (1% aqueous solution as a daily drinking water) or the autophagy inhibitor chloroquine (10 mg/kg, ip, 5 times a week) before the training. Western blotting analysis, TUNEL staining, H&E staining and transmission electron microscope were used to evaluate the activity of autophagy and the structure of the muscle fibers. RESULTS: The exercise training significantly stimulated the formation of autophagosomes, increased the LC3-II, cathepsin L and Bcl-2 levels, lowered the P62 level and increased the antioxidant capacity in the muscles. Meanwhile, the exercise training significantly improved the morphology of mitochondria, reduced the release of cytochrome c from mitochondria to cytoplasm, and slightly decreased the apoptosis rate in the muscles. Administration of trehalose increased the level of autophagy and protected the muscle fibers from apoptosis. Administration of chloroquine blocked autophagy flux and exerted detrimental effects on the muscles, which were ameliorated by the exercise training. CONCLUSION: Long-term regular exercise activates autophagy process associated with muscle establishment, and ameliorates the detrimental effects of chloroquine on skeletal muscles via restoring autophagy flux.

Health risk assessment of fluoride in drinking water from Anhui Province in China.

This study analyzes the concentrations and health risks of fluoride in 249 drinking water samples collected from different regions of Anhui Province in China. Results indicated that fluoride content in drinking water ranged from 0.12 to 1.94 mg L(-1) (mean = 0.57 mg L(-1)) in the following order: Huaibei plain region > Jianghuai hill region ≈ Dabieshan mountainous region > plain along the Yangtze River region > southern Anhui mountainous region. The fluoride contents were less than 0.50 mg L(-1) in 66.66 % of the drinking water samples, 0.51-1.0 mg L(-1) in 23.29 %, and higher than 1.0 mg L(-1) in 12.04 %. The fluoride levels in some samples were lower than the recommended values for controlling dental caries (0.50-1.0 mg L(-1)). The total fluoride intake from drinking water was between 0.14 and 2.33 mg per day in different regions of the province, supposing an individual consumes 1.2 L of water per day. Therefore, measures should be taken to increase fluoride intake in the Jianghuai hill region, Dabieshan mountainous region, plain along the Yangtze River, and southern Anhui mountainous region to control dental caries. On the other hand, the fluoride levels must be reduced in the Huaibei plain region to decrease endemic fluorosis. The results serve as crucial guidelines for managing fluoride safety in drinking water and controlling endemic fluorosis in different regions of Anhui Province.

[Location of telocytes in mouse bronchial and pulmonary tissues].

OBJECTIVE: To explore the location of telocytes in pulmonary tissues. METHODS: Electron microscopy, immunohistochemistry, primary cell culture and vital cell staining were used to identify the distribution of telocytes in mouse bronchial and pulmonary tissues. RESULTS: Telocytes were identified in the interstitial space between bronchial cartilage (cricoid) and smooth muscle by scanning and transmission electron microscope in mouse. By transmission electron micrscope and immunohistochemistry, telocytes were found in the interstitial spaces of lung parenchyma in connection with capillaries and bronchia. Telocytes expressed CD34, c-kit and vimetin by immunohistochemistry. After isolation, cultured telocytes demonstrated typical morphological feature, i.e. cells with telopode, which was seen as luminal structures with alternating thin and thick segments under electron microscope. CONCLUSION: Telocytes are present in the interstitial space between cricoid cartilage and smooth muscle.

[Hexachlorobenzene: its aging characteristic in different soils and accumulation in earthworm].

A simulation experiment was conducted to study the aging characteristics of hexachlorobenzene (HCB) in different soils and its bioaccumulation in earthworm. The results indicated that the aging of HCB in soils displayed a biphasic characteristic, i.e., quicker in the first 60 days and slowing down since then. The aging of HCB mainly occurred in the first 60 days during its contact with soil, and its aging rate in soils followed the sequence of paddy soil > red soil > fluvo-aquic soil. The accumulated amount and accumulation rate of HCB in earthworm decreased with increasing aging time. Though the soil extractable HCB decreased with increasing aging time, earthworm still had a higher HCB accumulation (457.6-984.3 ng x g(-1)) in its body due to its high HCB accumulation ability (the bioaccumulation factor BAF was between 3.74 and 6.35), giving a potential risk to soil ecological safety.

[Influence of aging on the extractability and bioavailability of hexachlorocyclohexane (HCH) in soil].

Influence of aging on the extractability and bioavailability of HCHs (alpha-, beta, gamma- and delta- isomers) in paddy soil were investigated in the lab under simulated circumstances. Results indicate that extractable HCHs decreased as their contact time with soil increased. The aging rate of HCHs in soil was rather high at the initial stage, and then slowed down in the rest of the time. During the first 60 days aging period, alpha-HCH, beta-HCH, gamma-HCH and delta-HCH dropped off 57.2%, 50%, 52.2% and 43.2% of the initial concentrations, about 90.5%, 87.4%, 72.4% and 84.4% of the total quantity of HCHs decreased in 180 d respectively due to high aging rate. Bioaccumulation of HCHs in earthworm displayed the same rule as aging, that is, the contents of HCHs in earthworm decreased as the incubation time extended, and so did bioaccumulation factors (BAF). The contents of HCHs accumulated in earthworm showing the order of alpha-HCH > beta-HCH > delta-HCH > gamma-HCH, while the accumulative ability expressing the rule of gamma-HCH > alpha-HCH > beta-HCH > delta-HCH in the first 15 d, and then alpha-HCH > beta-HCH > gamma-HCH > delta-HCH in the rest incubation time. Though the extractable HCHs decreased with aging, they still can be accumulated in earthworms, thus posing potential risk to soil environment.

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China.

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, sigmaDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by sigmaHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and alpha-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD+DDE)/DDT in soils under three land usages were: paddy field > tree land > fallow land, indicating that land usage influenced the degradation of DDT in soils. Ratios of p,p'-(DDD+DDE)/DDT > 1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.

[Kinetic characteristics of Cd2+ desorption in minerals and soils under simulated acid rain].

The kinetic characteristics of Cd2+ desorption in minerals and soils under simulated acid rain were studied by using the flow-stirred method. It showed that Cd2+ desorption could be described by first-order kinetics. Percents of desorption amounts of Cd2+ calculated were 70%-100% in red soil and goethite, and 25%-50% in latosols and kaolinite. Parabolic diffusion could describe Cd2+ desorption kinetics in latosols and not suitable for red soil and goethite and kaolinite. Cd2+ desorption, regarded as a heterogeneous diffusion in minerals and soils, could be fitted by Elovich equation more than Parabolic diffusion and two-constant equation. Cd2+ desorption could be divided into fast reaction and slow reaction. Except for latosols, fast reaction would be over during 60 min and be close to quasi-equilibrium. Adsorption forms of Cd2+ in soil surface could be exchangeable and specific. Fast reaction was relative to easily desorbed Cd2+. The affinity of edge hydroxyl to Cd2+ would lead to the difference of Cd2+ desorption rate and amounts. Increase of pH value in effluent indicated H+ consumption in the processes of Cd2+ desorption.