Flowering is an important process in the life cycle of plants to complete the transition from vegetative growth to reproductive growth and to ensure the yield and production of next generation. Therefore, flowering time is a considerable agronomic trait in plants. There are many factors influencing flowering time, including internal factors, such as hormone and carbohydrate, and environmental factors, such as light and temperature. Different plant species have evolved complicated networks to modulate the flowering time accurately in response to environmental cues and endogenous signals. Studies in Arabidopsis have led to the identification of the major flowering pathways: the photoperiod pathway, the vernalization pathway, the ambient temperature pathway, the autonomous pathway, the gibberellic acid (GA) pathway and the age pathway. Multiple flowering regulatory pathways converge to control the activation of floral integrator genes, such as FT and SOC1. The flowering time genes and their regulation pathways are highly conserved in Arabidopsis, rice and other higher plants. The key regulators of floral transition have been studied extensively in plants.
As aspects of protein posttranslational modifications, the ubiquitin/26S proteasome pathway and SUMOylation play key roles in almost every aspect of growth and development for plants, including the regulation of plant flowering time. Protein stability, degradation, location, and interaction with other proteins were also regulated under these pathways. The ubiquitination pathway usually contains three steps. First, the E1 (ubiquitin activating enzyme) forms a thioester bond with the C terminus of the 76amino acid ubiquitin protein. Second, the activated ubiquitin is transferred to an E2 (ubiquitin conjugating enzyme). Third, with the help of the E3 ligase, ubiquitin is transferred to the substrate by E2, and at last forms a ubiquitinated substrate protein. These processes are then repeated to attach new ubiquitin molecules to the substrate protein, and polyubiquitination has been shown to be essential for recognition and degradation of the substrate by the 26S proteasome. The polyubiquitin chain can be disassembled by the DUB (deubiquitinating enzyme) to release ubiquitin moieties. The process of SUMOylation is similar with ubiquitination except for some small differences. 
Flowering time appears to be regulated by modulation of protein stability and degradation mediated by ubiquitination and SUMOylation. According to the study of Arabidopsis genome, there are more than 1 400 genes encoding components of the ubiquitin/26S proteasome pathway. Many of these genes mediate the degradation of the key proteins in the flowering pathways, such as CO protein. In this paper, recent advance on mechanisms of ubiquitination and SUMOylation regulating flowering time was discussed. First, the functions of the ubiquitination and related genes in the photoperiod pathway, as a major part of this review, were described in details. Furthermore, ubiquitination taking part in photoreceptor degradation, circadian clock regulation, and the modulation of the downstream gene expression and protein stability was discussed. The second part was that the ubiquitination involved in the temperature pathways including the vernalization pathway, the ambient temperature pathway, and the shortterm cold stress pathway. The function of DELLA proteins was discussed in the third part. In the fourth part, the roles of SUMOylation and its related genes in the flowering regulation pathways were briefly summarized. At last, some suggestions were given on the methods to study the function mechanisms of ubiquitination and SUMOylation on flowering time. We hope that this review will provide a foundation for a better understanding of the role of protein posttranslational modifications in flowering pathways.

With the advent of molecular marker techniques in the past two decades, genome-wide association study (GWAS) was proved to be an effective tool to reveal genetic architecture of complex traits in human, animal and plants. GWAS typically focuses on associations between genetic markers and quantitative traits in natural populations and takes advantage of recombination events in the evolutionary history. In human, more than 6 000 variant loci were discovered to associate with > 500 quantitative traits and complex diseases. In animals, GWAS was conducted specially on economically important traits, genetic defect diseases and other complex diseases of the main livestock and poultries. In plants, GWAS has been applied to study flowering time, developmental traits and agronomical traits of Arabidopsis, rice, maize and cotton. 
Despite the initial success of GWAS that has been achieved, the uncovered associated loci usually have small effects on phenotype and only account for very limited phenotypic variation. The remaining unexplained genetic variance is the socalled “missing heritability”. Three possible factors were responsible for the failure of detecting the cause loci. First, the efficiency of detecting the smalleffect loci is very low and more smalleffect loci are undiscovered. Most GWASs proceed on the base of the assumption that common phenotypic variation is caused by common genetic variation. The power to detect the cause loci is a function of allele frequency, thus it is difficult to identify the functional variants at low frequency though they have larger effects on the phenotype. Second, GWAS was unable to deal with the phenotypic variances caused by structural variation (i.e. copy number variation). Third, current GWASs pay little attention to the interactions among the genetic variances and ones between genetic and environmental factors, which have been affirmed by the results of linkage analysis.
New strategies for GWAS were discussed. The package GMDR-GPU was developed to analyze epistasis effects, and the software QTXNetwork could simultaneously research single locus effect, digenic epistasis effect and their environment interactions in a full genetic model. The unbiased prediction of genetic effects could be obtained.
GWAS would make breakthrough in two aspects for the foreseeable future, due to the increasing availability of high throughput genome sequencing for human and plants. First, the increased advances in “omics” technology (transcriptomics, proteomics and metabolomics) will provide an opportunity to study the association of phenotypic variations with mRNA, protein or metabolite, which position the omics loci linked to the interested traits. Second, multitrait GWAS will improve statistical power for identifying genes contributing to complex traits.

Mollusk shell is an exoskeleton made up of organic mineral particles and its function is to protect the inner soft body from predators and environmental damage. Due to its superior mechanical properties, such as stiffness, fracture toughness, and tensile strength, the mollusk shell has been investigated as an excellent biomaterial and as biomineralization model over the past decades. Previous studies have revealed that mollusk shell was consist of a mineral phase (calcium carbonate) and an organic matrix (proteins, polysaccharides and lipids). The organic matrix intercalated in a shell is generally assumed to play an important role in crystal nucleation, crystal orientation, crystal size regulation, and crystal polymorphism and contributing to the shell’s mechanical properties. Recent advances on ease and availability of high throughput RNA-sequencing have resulted in a sharp increase in transcriptome data for invertebrate biominerals. However, for -Mytilus, bio-mineralization mechanisms and shell formation were restricted to obtain by deficiency of transcriptome information. 
To understand the molecular diversity of matrix proteins from mussel shell and to develop a transcriptome from the adult mantle tissue of M. coruscus, the transcriptome sequencing of M. coruscus mantle was performed by Illumina platform. A total of 77 445 588 paired end reads amounting to 6 Gb of sequence data were generated and further assembled de novo with Trinity software. A transcriptome was produced after filtering and quality checking, yielded a final set of 106 425 high quality mantle unigenes for analysis. To obtain an integrated view of the transcriptional events of bio-mineralization related processes in M. coruscus mantle, the unique transcript library was screened for reported shell matrix proteins (SMPs). Taken together, 124 unigenes were identified with significant hits (E value <10^-5) to 12 reported bio-mineralization related proteins including all known Mytilus SMPs. The most abundant unigenes out of 124 matched ones were annotated as calponin, followed by fibronectin, perlucin, nacrein, and Shematrin. Most of homologues were from Crassostrea, Pinctada, Haliotis, and Mytilus, which showed that M. coruscus mantle unigene encoded putative proteins exhibiting sequence similarities with previously characterized SMPs of other Bivalvias, indicating a common originate for these SMPs. 
In conclusion, a comprehensive transcriptomic resource for the Mytilus SMPs was presented in this paper, providing insight into the protein composition of the shell. The transcriptomic resource can also provide a foundation for further investigations on the formation and bio-mineralization of mussel shell.

Transfection, involving the transfer of exogenous DNA to eukaryocyte cells, is a common technique in molecular and cellular biology, including calcium phosphate transfection, electroporation, lipofection and so on. Calcium phosphate transfection is one of the major methods for DNA transfer to eukaryocyte cells and with lower toxicity and cost than lipofection. However, the application of calcium phosphate transfection method was limited due to its low transfection efficiency and instability. 
To establish a highly efficient and stable transfection approach to overexpress exogenous protein abundantly in HEK293T cells in vitro, green fluorescent protein (GFP) plasmid DNA was transfected by using calcium phosphate with optimal DNA amount and vortex time of calcium phosphateDNA complex in absence or presence of common transfection enhancers including glycerol, sodium butyrate, and chloroquine. 
The protocol of calcium phosphate transfection was as follows. First, HEK293T cells were seeded in a sixwell plate, incubated for 8-24 hours at 37 ℃ in a humid incubator with 5% CO₂, and then the cells were transfected after cell confluence reached 50%-80%. Second, calcium phosphate-DNA complex was prepared. Mixed GFP DNA plasmid with 25 μL of 2.5 mol/L CaCl₂ solution in a roundbottom tube, added sterile water up to 250 μL, blended 10 μL of phosphatesolution ［V(70 mmol/L Na₂HPO₄)∶〖_V(70 mmol/L NaH₂PO₄)=1∶1］ with 250 μL of 2×Hepes buffer solution and added to the former solution, added calcium phosphateDNA mixture into HEK293T cells one drop at a time immediately after vortex. Finally, transfection efficiency was detected by fluorescence imaging in absence or presence of common transfection enhancers including glycerol, sodium butyrate, and chloroquine. The dosage of DNA, duration of vortex and concentrations of three common transfection enhancers were optimized during or after transfection. 
The results showed that the optimal GFP plasmid DNA amount was 3 μg/well. Compared with GFP plasmid DNA amount of 1 or 2 μg/well and 4 or 5 μg/well, average transfection efficiency of optimal amount was improved by 50% and 70%, respectively. Higher transfection efficiency was also detected when the vortex time was 10 s. Under these optimal conditions, transfection efficiency of treatment with 15% glycerol alone for 6.5 min was significantly higher than that for 2.5, 4.5, 8.5, or 10.5 min. When the HEK293T cells were treated with the combination of 15% glycerol with 5 mmol/L sodium butyrate or 500 μmol/L chloroquine alone, transfection efficiency was improved by 80% and 75%, respectively. Meanwhile, GFP fluorescence intensity was enhanced. 
Compared to lipofectamine reagents, calcium phosphate transfection with enhancers is more efficient, less toxic and less expensive. Therefore, this approach can be used to overexpress largescale proteins in the HEK293T cells in vitro, or to package lentiviruses/retroviruses. It is especially applicable for in vitro high flux expression and preparation for various glycosylated proteins such as cancer diagnosis markers.

Rich coat color is not only an important biological characteristics, but also a significant economic value for wool producing animals. Guanine nucleotide binding protein alpha q (Gnαq) is a downstream subunit of heterologous trimeric G protein. It plays a significant role in the performance of endothelin B receptor, which is involved in regulating coat hair of animals. 
In order to understand how Gnαq gene acts in the process of manipulating mammalian hair color, reverse transcriptionpolymerase chain reaction (RT-PCR), quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to detect the difference, the relative expression of Gnαq gene in different mice with two kinds of colors (white and black). The localizations of Gnαq protein were analyzed by immunohistochemistry in different color skin tissues of mice. 
A partial sequence of Gnαq gene with the length of 140 bp was successfully amplified by PCR. Blasting in NCBI showed that the Gnαq sequence of mice had a high homology with other species, especially with rat and gray dwarf hamster, with the similarity of 98% and 92%, respectively. qRT-PCR and western blotting results showed that the relative expression of Gnαq mRNA and Gnαq protein in black skin of mice was significantly higher than those in the white skin of mice (P<0.01). According to the results of immunohistochemistry, the Gnαq protein was expressed around the cells in hair follicles of mice, as well as in the outer root sheath and hair bulb of hair follicle.
In conclusion, the expression of Gnαq is significantly different between the white and black skin tissues of mice, and it is distributed in the outer root sheath and hair bulb of hair follicle, suggesting that the Gnαq gene may play a critical role in the process of coat color formation in mice.

Sorghum halepense (L.) Pers is an important quarantine weed, which is native to the Mediterranean region, and now is considered as one of the ten worst weeds in the world. The species is mainly dispersed by seeds. Sorghum almum Parodi is also an important weed,and Sorghum bicolor （L.） Moench and Sorghum sudanense (Piper) Stapf are two cultivated plants. Due to their morphological similarity, it is difficult for entry-exit inspection and quarantine departments to properly and quickly identify the seeds of S. halepense from those of its closed species. Therefore, how to identify the seeds of S. halepense from those of its congeneric species is urgently needed. 
In this paper, seeds from the above four species were extracted with petroleum ether to get their extractions, which were analysed by ultraviolet (UV) spectrophotometer (Unicam UV540) to get 200 UV absorbance data within 200-400 nm with 1 nm slit and at a scan rate of 0.5 s. From these 200 absorbance data, the sensitive wavelengths whose absorbance data could be separated each other were firstly identified by SPSS 16.0 using one-way analysis of variance (ANOVA). From these preliminarily selected sensitive wavelengths, more sensitive wavelengths with high information load were further identified by principal component analysis (PCA). With the absorbance data of these informative wavelength spectra in relation to four species, both cluster analysis and PCA were applied to produce a dendrogram and a twodimensional scatter plot, respectively. In order to verify the effect of the informative wavelengths which were selected by one-way ANOVA and PCA, a spectrum chart, a dendrogram, a two-dimensional scatter plot from PCA were directly produced on the basis of the absorbance data corresponding to the 200 wavelengths. 
According to the above procedures, sixtythree wavelengths were preliminarily selected by using ANOVA. From these wavelengths, eighteen informative wavelengths from 283 to 300 nm with a step of 1 nm were identified by PCA. On the dendrogram, the scatter plot and the spectrum chart produced based on these eighteen informative wavelengths, the seed samples of S. halepense and its three congeneric species were well separated each other. All these three schemes were better than those on the basis of the absorbance data corresponding to the 200 wavelengths in the seed identification of these four Sorghum species. 
The above results indicate that the extraction scheme with petroleum ether, and the selected eighteen informative wavelengths by ANOVA and PCA, as well as the charts by cluster analysis, PCA, or directly based on absorbance data are effective to identify the seeds of S. halepense from those of S. bicolor, S. almum and S. sudanense.

Soil animals play an important role in terrestrial ecosystems. It can not only indicate the subtle variation of habitats, but also reflect the trend of ecological communities. Diversity of soil animals is an important part of biodiversity study of soil. In recent years, desert habitat diversity in Baijitan National Nature Reserve of Lingwu in Ningxia has formed along with the development of control engineering. However, there is lack of the information on the diversity and distribution patterns of soil animals, the correlation between distribution patterns of soil animals and process of habitat change.
Knowledge of the temporal variability of soil animal populations and species is crucial to understand the soil community dynamics. The main purposes of this study were to elucidate 1) the characteristics and differences of soil animal diversity at different habitats, and 2) the ecological factors affecting the distribution pattern and diversity of soil animals. These studies will have important significance on monitoring and conservation of biological diversity.
To understand diversity features of soil faunal community in desert landscape, seven sample plots with the habitat types of desert steppe (DS), artificial sandfixation land (AS) and shifting and semi-shifting dune land (SL) were selected as study sites. The area of each plot is about 600 m² (6 m×100 m). The segregate efficiency of soil animals among the 0-5, 5-10, 10-15 to 15-20 cm layer in different plots was studied using Tullgren and Baermann methods in August, 2013. Plant diversity was surveyed by quadrat method. Soil temperature, nutrients and physicochemical factors were measured.
By preliminary identification, there were 260 specimens of soil animals, which belonged to 2 phyla, 3 classes, 8 orders and 18 families. Tarsonemidae, Carabidae and Cicadellidae were the dominant groups. Density index and species richness index of DS were significantly higher than AS and SL (P<0.05). ShannonWiener diversity index of DS were significantly higher than AS (P<0.05). Simpson dominance index of SL was significantly higher than DS (P<0.05). Soil animals were principally assembled on surface layer. The vertical distribution of soil animals decreased with increasing soil depth. The surface aggregation of soil animals in SL was more obvious than that of the AS and DS. The density of soil animals, Simpson dominance index, species richness index and Shannon-Wiener diversity index were highest on 0-5 cm soil layer in DS, SL and AL. Compared with the same soil layer, richness and Shannon-Wiener diversity indices showed DS>AS>SL, which turned out that in succession of SL to DS, the density and the number of soil animals increased. Redundancy analysis showed that soil water content, organic carbon, total nitrogen, total phosphorus, and plant diversity index were sensitive to the diversity of soil animals. Partial correlation analysis showed that the main factors affecting the soil animal diversity of surface soil layer were soil temperature, soil water content, organic carbon, total nitrogen and plant diversity index, and the factors affecting the diversity of animal of deep soil layer was soil water content.
It is concluded that soil animals in desert habitats are principally assembled on surface layer. Diversity of soil animals is obviously affected by habitat heterogeneity, which tend to be more complicated with higher habitat heterogeneity and lower desertification degree of soil. Soil water content, organic carbon and plant diversity index are the main ecological factors affecting the diversity of desert soil animals.

Flue-cured tobacco is a major cash crop in China. Due to the scarcity of land resources, continuous cropping of tobacco was very common all over the country. However, the continuous cropping phenomenon would lead to change of soil properties and nutrient imbalance, seriously affecting yield and economic merits of tobacco. Therefore, it was quite necessary to optimize the soil microbial environment and promote the effective absorption and utilization of fertilizers, to improve the yield and quality of flue-cured tobacco. It has been reported that soil amendments could improve the physical and chemical properties of soil, as well as the nutrient status, which could also regulate pH and organic matter of soil to increase the availability of N, P and K contents. In a word, soil amendments were effective to promote the productivity of degraded soils. Microbial fertilizer could improve the microenvironment of plant rhizosphere, by increasing the diversity of microbial species and improving growth and nutrient absorption capacity of root. 
There have been many reports about the effect of microbial fertilizer or soil amendment application on growth and development of crops, but the mixed application effect of microbial fertilizer and soil amendments was rarely mentioned. In this study, the combining effects of effective microorganisms (EM) and soil amendments on agronomic characteristic and quality of flue-cured tobacco were investigated. 
A field trial designed as randomized block was carried out to reveal the effects of EM and soil amendment treatments (T₁: conventional film transplanting; T₂: conventional film transplanting + EM + soil amendments; T₃: well cellar type transplanting; T₄: well cellar type transplanting + EM + soil amendments) on leaves, root and stem development of flue-cured tobacco during the growth period. Meanwhile, the effects of different treatments on yield and quality of flue-cured tobacco. The results showed that the mixed application of EM and soil amendments promoted the growth of tobacco plant, especially at the maturity stage. Simultaneously, the mixed application of EM and soil amendments also improved the yield and quality of tobacco leaves, and optimized the grade of tobacco leaves. The yields of T₂ and T₄ treatments were 1 909.31 kg/hm² and 2 134.91 kg/hm², which were higher than those of T₁ and T₃ by 5.21% and 7.13%, respectively. The output values of T₂ and T₄ were 29 460.69 Chinese Yuan/hm² and 35 162.05 Chinese Yuan/hm², higher than those of corresponding controls (T₁ and T₃) by 3.84% and 8.72%, respectively. For chemical composition, the mixed application of EM and soil amendments increased the contents of nicotine, potassium and chlorine, but decreased the content of total sugar in flue-cured tobacco leaves. Furthermore, the mixed application of EM and soil amendments reduced the Schmuck value and the ratio of total sugar to nicotine, increased the ratio of reducing sugar to total sugar. The treatments with EM and soil amendments enhanced the sensory quality of fluecured tobacco leaves, and the total scores of T₂ and T₄ increased 2.30 and 2.67, respectively, compared with the corresponding controls (T₁ and T₃). 
In a word, the mixed application of EM and soil amendments shows practical value not only in improving the grade of the fluecured tobacco leaves, but also improving their yields and quality.

Tomato, one of the most important vegetable crops, is widely cultivated around the world. Blossom drop is a common growing problem that can be extremely frustrating to the tomato production. The most frequent cause of tomato blossom drop is inappropriate temperature. In hot season, the stigma exsertion often occurs and causes the unsuccessful selfpollination, and finally markedly lowers fruitsetting.
In this study, exogenous spray of indole-3-acetic acid (IAA, natural auxins), gibberellin A₃ (GA₃), jasmonic acid (JA) and 2, 4-epibrassinolide (EBR) with different concentrations on tomato flower buds was conducted under controlled heat stress conditions using tomato cv. “Micro-Tom”, aiming to evaluate the influence of plant hormones on the heat-induced stigma exsertion. The growth of stamen and pistil was compared among different treatments. Meanwhile, using quantitative realtime polymerase chain reaction (qRT-PCR), the changes of expression levels of some important genes involving auxin (IAA), gibberellin (GA), and abscisic acid (ABA) signaling pathways, as well as phytochrome interacting factor (PIF) family genes were examined as exposed to exogenous GA₃ or paclobutrazol (PAC) under moderate heat stress.
The results indicated that tomato grown under the moderate heat stress developed the flowers with longer style and protruding stigma. Spraying GA₃ under the moderate heat stress accelerated the tomato stigma exsertion, and the percentage of flowers for the stigma exsertion increased, whereas PAC, the inhibitor of gibberellin biosynthesis, could rescue the extent of stigma exsertion to some degree. Moreover, continuous GA₃ application on the flower buds could significantly increase the tomato fruitsetting. Furthermore, JA treatment showed similar effects on increasing the percentage of flowers for stigma exsertion, but the exsertion extent was not obvious. However, the effect of IAA and EBR treatments on stigma exsertion also was not obvious. The expression analysis on eight hormonerelated genes as well as four SlPIF genes in tomato stamen and pistil showed that the relative expression level of the gibberellin biosynthesis genes SlGA20ox2, encoding the main GA20ox in tomato, was significantly up-regulated in pistil when the flower buds were treated with GA₃ under the moderate heat stress, whereas the gene SlDELLA, a repressor in the gibberellin signaling pathway, was down-regulated. In contrast, in stamen, SlGA3ox1, expected to be a negative feedback regulation in the gibberellin signaling pathway,〖WTBX〗 〖WTBZ〗was significantly upregulated. The genes SlNCDE1 encoding a 9-cis epoxy-carotenoid dioxygenase and SlCYP707A1 participating in putative (+) ABA 8’-hydroxylase metabolism were up-regulated in stamen. Moreover, SlPIF1-1 and SlPIF4 were down-regulated in pistil. 
In conclusion, under the moderate heat stress, gibberellin participates in the stamen and pistil elongation growth and has an important regulatory role in tomato stigma exsertion through gibberellin biosynthetic pathway, and the PIF may be involved in the regulation of gibberellin inducing tomato stigma exsertion event. Our study may provide some helpful information for further elucidating the precise roles of plant hormones on tomato stigma exsertion as well as enhancing fruit yields under the moderate heat stress.

Excess nutrients, especially phosphorus, running off from agricultural lands have contributed greatly to the eutrophication of water bodies in China. Drainage ditches are important conduits for drainage flows and unavoidably receive the discharge of nutrients, particulate matters, and other chemicals. Thus, more and more attention has been focused on the role of agricultural drainage ditch in water pollution control. However, few of the research were reported on drainage ditches of paddy field in southern hilly tea field watershed.
In this paper, sediment samples collected from drainage ditch of paddy field in southern hilly tea field watershed were analyzed, according to the water discharging distance. The physicochemical properties of sediments were determined and phosphorus isothermal experiments were also conducted. 
The result showed that water discharging distance had a significant influence on ditch soil properties. The concentrations of total phosphorus (TP), oxalateextractable ferric iron (Fe_ox), Al_ox and P_ox increased with the discharging distance. The accumulation of P in the ditch soil was significantly correlated with total organic matters (TOM) and Al_ox, and the existence of TOM enhanced the activity of soil phosphorus. The degree of phosphorus saturation (DPS_ox) ranged from 1.50%-2.69%, much lower than the threshold value of P release. Both Langmuir equation and Freundlich equation could well describe the phosphorus adsorption behavior of ditch sediments, and the maximum P adsorption (S_max) ranged from 646.62 mg/kg to 754.17 mg/kg; Freundlich’s adsorption constant (K_f) ranged from 271.81 L/kg to 338.74 L/kg. The sediments sampled from the end of the ditch had the maximum values of 338.74 L/kg and 754.17 mg/kg for K_f and S_max, respectively, which suggested that the sediment had the highest P adsorption capacity. The parameters calculated from the Freundlich and Langmuir isotherms ranged from 0.000 to 0.004 mg/L. In isothermal adsorption experiment, the adsorbed P amounts raised with the water discharging distance, but no significant differences were observed among P adsorption amounts of different ditch soils.
In conclusion, for the studied ditch, sediment properties change as water discharging distance increasing, but not for P adsorption capacity. Besides, the sediments have large intrinsic P adsorption capacities and low risk of P release, which indicate that the ditch can be improved as ecological ditch to further P retaining.

Ferrous ion (Fe²⁺) and reduced sulfur ion (S^2-) were main toxic elements in the cold waterlogged paddy soil. How to remove Fe²⁺ and S^2- effectively was the key to improve the quality of cold waterlogged paddy soil. Steel slag has been confirmed as a good sorption material in waste water treatments for some heavy metals and organic pollutants. These properties suggested that steel slag might have the ability to adsorb and fix Fe²⁺ and S^2- from cold waterlogged paddy soil, and improve the quality of cold waterlogged paddy soil by reducing Fe²⁺ and S^2-.
The characteristics of Fe²⁺ and S^2- adsorptiondesorption by steel slag were studied in the present study, to reveal whether steel slag was a good sorption material for Fe²⁺ and S^2-, and to understand whether steel slag had the potentiality in controlling Fe²⁺ and S^2- and improving the quality of cold waterlogged paddy soil. 
The sorption of Fe²⁺ and S^2- by steel slag was studied using batch incubation experiments, while the effects of adsorption time (0.25, 0.5, 1, 1.5, 2, 3 or 4 h, respectively), Fe²⁺ and S^2- concentration (10, 30, 50, 100, 150 mg/L Fe²⁺ or 10, 30, 50, 80, 100 mg/L S^2-, respectively), pH (the pH range of adsorption system was from 1.00 to 12.00), temperature (designed as 15, 25, 35 or 45 ℃, respectively) and ionic strength (0.01 mol/L NaCl, 0.02 mol/L NaCl or 0.005 mol/L MgCl₂, respectively) in adsorption reaction solution on the sorption were investigated.
Except for adsorption time experiments, all treatments were shook 3 h and stood for one night for complete adsorption reaction. Then, the adsorption reaction solution was centrifuged at 4 000 r/min for 10 min and filtrated for further determination of Fe²⁺ and S^2- concentrations. The stability of Fe²⁺ and S^2- adsorbed by steel slag was further validated by desorption experiments under similar conditions.
The results showed that the adsorption kinetics of Fe²⁺ and S^2- by steel slag followed the Elovich kinetics equation, and the correlation coefficients were 0.94 and 0.89 respectively. Freundlich isotherm model could simulate the adsorption processes better than other models, and the correlation coefficients for Freundlich isotherm model were 0.97 and 0.94 respectively. Their parameters were all less than 1, which indicated that the adsorption processes were nonpreferential adsorption. Free energy variation (ΔG) for the Fe²⁺ sorption was greater than 0, which indicated that this reaction was nonspontaneous; but ΔG for the S^2-sorption was less than 0, which indicated that this reaction was spontaneous. The adsorption process was endothermic because high temperature was beneficial to their adsorption. And the adsorption process had greater pH adaptability range from 1.50 to 11.50. The adsorption of Fe²⁺ was major in inner sphere complexation, while the adsorption of S^2- was major in outer complexation, which were consistent with the results in thermodynamic experiments. The adsorption rates were all very high, but the desorption rates were low in all experimental conditions, which showed that the adsorption stability of steel slag was superior. 
On the whole, steel slag had good ability to remove Fe²⁺ and S^2-, might be a potential adsorbent in controlling Fe²⁺ and S^2- and improving the quality of cold waterlogged paddy soil.

Chromium (Cr) is considered to be one of the major heavy metal pollutants in marine environment, and in existence of two valence states: hexavalent chromium ［Cr(Ⅵ)］ and trivalent chromium ［Cr(Ⅲ)］. The source of Cr pollution in marine environment was mainly from discharge of effluents by a variety of industries. Cr(Ⅵ) is considered as the most toxic form of Cr, whereas Cr(Ⅲ) is much less toxic. Cr(Ⅵ) is nonbiodegradable and can rapidly accumulate in creatures and reach toxic levels in short periods of time. Although the bioaccumulation of heavy metals in many creatures has been well studied, details on mechanisms and differences of Cr(Ⅵ) bioaccumulation in different marine creatures remain unclear.
In this paper, the bioaccumulation processes of Cr(Ⅵ) in muscle tissues of crustaceans Exopalaemon carinicauda and Portunus trituberculatus were investigated, and the kinetic parameters of the Cr(Ⅵ) accumulation and elimination were determined using the semi-static two-compartment kinetic model, which included biouptake rate constant (k₁), bioelimination rate constant (k₂), bioaccumulation factor (BCF), and biological half-life (B_1/2). The kinetic model described the transport of Cr(Ⅵ) between ambient seawater and muscle tissue of two kinds of crustaceans. The modeling results indicated that the range of k₁, k₂, BCF, Cr(Ⅵ) content under an equilibrium condition (C_Amax) and B_1/2 was 3.37 to 20.65, 0.058 to 0.121, 58.10 to 171.00, 8.55 to 290.52 mg/kg, 5.74 to 11.95d, respectively, and the average value of k₁, k₂, BCF, C_Amax and B_1/2 was 11.00, 0.089, 110.13, 116.57 mg/kg and 8.50 d for Cr(Ⅵ) in the muscle tissue of E. carinicauda. However, the range of k₁, k₂, BCF, C_Amax and B_1/2 was 4.36 to 12.44, 0.115 to 0.154, 37.91 to 80.81, 4.85 to 56.87mg/kg, 4.50to6.03 d, respectively, and the average value of k₁, k₂, BCF, C_Amax and B_1/2 was 7.70, 0.131, 56.53, 25.66 mg/kg and5.38 d for Cr(Ⅵ) in the muscle tissue of P. trituberculatus. It was found that the k₁, k₂ and BCF generally decreased and the C_Amax and B_1/2 increased in the muscle tissues of E. carinicauda and P. trituberculatus with the increase of Cr(Ⅵ) exposure concentration in ambient seawater. In sum, the bioaccumulation content of Cr(Ⅵ) in the muscle tissue of E. carinicauda is higher than that in P. trituberculatus, and the bioaccumulation rate in early stage is higher than in later stage. Meanwhile, the elimination rate of Cr(Ⅵ) in the muscle tissue of P. trituberculatus is faster than that in E. carinicauda, and the elimination process of Cr(Ⅵ) is mainly in the initial stage, and the elimination ability of E. carinicauda is weaker than that of P. trituberculatus.

Sucrose accounts for about 90% of the total amount of sugar in China. However, the mechanization degree and working efficiency on planting, harvesting and sugaring of sugarcane in China is far lower than western countries, and especially the problem of high impurity rate affecting the sugaring efficiency after sugarcane harvest is more serious. Because the tail of sugarcane is low in sugar, removing the tail of sugarcane in the harvest process can effectively improve the efficiency of sugaring.
As the mechanical strength of the tail is significantly lower than the middle and the base of sugarcane stalk, an idea on design of the tail-reasonable tailbreaking mechanism was designed.
Because the flexure strength, compressive strength and shock strength of the tail were significantly lower than any other part of the sugarcane, the design scheme of the tail-breaking mechanism on the whole stalk sugarcane harvester was discussed. Three kinds of tail-breaking mechanism were designed by analyzing the design requirements and working mechanism. Co-simulation analysis by ANSYS and ADAMS was employed to compare the difference among the three kinds of tail-breaking mechanism. 
The results showed that the anti-movement tail-breaking mechanism was proved to be reasonable and feasible, with better passing ability, and smaller degree of jumping up and down or running around. Besides, it also had good function of tail-breaking.
Optimal structure parameters for this anti-movement tail-breaking mechanism were obtained by virtual tests as follows: 320-330 mm of center distance between the top and bottom tail-breaking wheels, and 5-10 degree of stagger angle between the top and bottom tail-breaking elements. According to the optimal structural parameters, the physical prototype verification test was operated with the whole stalk sugarcane harvester with anti-movement tail-breaking mechanism. The results showed that, the tail-breaking mechanism was reasonably practicable with the tailbreaking rate of 92.5%, and the ideal tailbreaking rate could reach 87.5%. It can provide a reference for the design of tail-breaking mechanism for the whole stalk sugarcane harvester.