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Increasing evidence shows that improved nitrogen management can enhance lodging resistance and lower internodes play a key role in the lodging resistance of rice. However, little is known about the cellular and molecular mechanisms underlying the enhanced lodging resistance under improved nitrogen management. In the present study, two rice varieties, with contrasting lodging resistance, were grown under optimized N management (OPT) and farmers’ fertilizer practices. Under OPT, the lower internodes of both cultivars were shorter but the upper internodes were longer, while both culm diameter and wall thickness of lower internodes were dramatically increased. Microscopic examination showed that the culm wall of lower internodes under OPT contained more sclerenchyma cells beneath epidermis and vascular bundle sheath. The genome-wide gene expression profiling revealed that transcription of genes encoding cell wall loosening factors was down-regulated while transcription of genes participating in lignin and starch synthesis was up-regulated under OPT, resulting in inhibition of longitudinal growth, promotion in transverse growth of lower internodes and enhancement of lodging resistance. This is the first comprehensive report on the morpho-anatomical, mechanical, and molecular mechanisms of lodging resistance of rice under optimized N management.

Potassium (K) fertilizer additions can result in high crop yields of good quality and low nitrogen (N) loss; however, the interaction between K and N fertilizer and its effect on N2O emissions and associated microbes remain unclear. We investigated this in a pot experiment with six fertilizer treatments involving K and two sources of N, using agricultural soil from the suburbs of Wuhan, central China. The aim was to determine the effects of the interaction between K and different forms of N on the N2O flux and the abundance of nitrifying and denitrifying microbial communities, using static chamber-gas chromatography and high-throughput sequencing methods. Compared with no fertilizer control (CK), the addition of nitrate fertilizer (NN) or ammonia fertilizer (AN) or K fertilizer significantly increased N2O emissions. However, the combined application (NNK) of K and NN significantly reduced the average N2O emissions by 28.3%, while the combined application (ANK) of K and AN increased N2O emissions by 22.7%. The abundance of nitrifying genes amoA in ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) changed in response to N and/or K fertilization, but the denitrifying genes narG, nirK and norl were strongly correlated with N2O emissions. This suggests that N or K fertilizer and their interaction affect N2O emissions mainly by altering the abundance of functional genes of denitrifying microbes in the soil-plant system. The genera Paracoccus, Rubrivivax and Geobacter as well as Streptomyces and Hyphomicrobium play an important role in N2O emissions during denitrification with the combined application of N and K.

The non-contact compensation type AC voltage regulator possesses the advantages of small size, high efficiency, low cost, etc. due to its simple structure and convenient control, and is widely used in the field of AC voltage regulation technology field. However, the non-contact compensation type AC voltage regulator belongs to the class of voltage regulation. And the characteristics of the discontinuous system has the disadvantages of low control precision and weak system reliability. Fuzzy control strategy, through fuzzification and approximate reasoning, can solve the problem of such discontinuous control systems. Some research work shows that using the fuzzy membership strategy to optimize the switching rules of the control system can greatly improve the control precision of the voltage regulation, that is, can improve the regulation accuracy of the AC voltage regulator. The experiment results verify that the regulation accuracy of the system after optimizing the switching rule is 5-10 times pre-set, which proves the effectiveness of the improvement.

The type VI secretion system (T6SS) is a versatile molecular machinery widely distributed in Gram-negative bacteria. The activity of the T6SS is tightly regulated by various mechanisms, including quorum sensing (QS), iron concentration, and transcriptional regulators. Here we demonstrated that the stringent response regulator, RelA, contributes to bacterial resistance to multiple environmental stresses in Yersinia pseudotuberculosis. We also revealed that the stress resistance function of stringent response (SR) was partially mediated by the general stress response T6SS4 system. RelA positively regulates the expression of T6SS4 to combat various stresses in response to nutrition starvation collectively mediated by the RovM and RovA regulators. These findings revealed not only the important role of T6SS4 in SR induced stress resistance, but also a new pathway to regulate T6SS4 expression in response to starvation stress.

Mycothiol (MSH) plays a major role in protecting cells against oxidative stress and detoxification from a broad range of exogenous toxic agents. In the present study, we reveal that intracellular MSH contributes significantly to the adaptation to acidic conditions in the model organism Corynebacterium glutamicum. We present evidence that MSH confers C. glutamicum with the ability to adapt to acidic conditions by maintaining pHi homeostasis, scavenging reactive oxygen species (ROS), and protecting methionine synthesis by the S-mycothiolation modification of methionine synthase (MetE). The role of MSH in acid adaptation was further confirmed by improving the acid tolerance of C. glutamicum by overexpressing the key MSH synthesis gene mshA. Hence, our work provides insights into a previously unknown, but important, aspect of the C. glutamicum cellular response to acid stress. The results reported here may help to understand acid tolerance mechanisms in acid sensitive bacteria and may open a new avenue for improving acid resistance in industry strains for the production of bio-based chemicals from renewable biomass.

Reducing water input and CH4 emission while maintaining grain yield is important for the sustainable rice production in south China. However, water-saving technology has not been widely adopted by farmers because of constrains in handling, effectiveness and reliableness. Recently a simplified and easy-to-use alternate wetting and drying technology, namely “safe” AWD, has been developed and recommended to farmers in Asian countries. However, the performance of the safe AWD technology has not yet been evaluated in south China. The objective of this study was to determine whether the safe AWD technology could maintain grain yield with reduced water input and CH4 emission as compared to the conventional farmer’s practice (FP) in south China. Two on-station field experiments were conducted in Guangzhou, Guangdong province during 2014 early and late seasons. In the early season, a hybrid rice variety, Tianyou 3618 (TY3618), was arranged in a randomized complete block design with three water treatments, i.e., AWD15, AWD30 and continuous flooding (CF). In the late season, a split-plot design was employed with four water management (AWD15, AWD30, CF and FP) as main plots and two varieties as subplots. The two varieties were TY3618 and Hefengzhan (HFZ, inbred). Field water level and soil water potential were recorded daily and the CH4 emission was monitored at 7-day intervals. Crop growth, grain yield and water productivities were measured. Results showed that grain yields under AWD15 and AWD30 were comparable with CF, while water input and total CH4 emissions were significantly reduced under the two AWD treatments for both seasons. In the late season, there were no significant differences in grain yield among the four irrigation treatments for HFZ. While for TY3618, grain yield in AWD30 was significantly lower than AWD15. Irrigation water input in AWD15 and AWD30 was 19.4% and 29.7% lower, and irrigation water productivity was 31.7–37.6% and 48.4–53.2% higher than FP, respectively. Over all, no significant differences were found in maximum tiller number, leaf area index, total aboveground dry weight, among the four irrigation treatments for HFZ. While for TY3618, the crop growth rate during grain-filling stage in AWD30 was significantly lower than CF and FP. The CH4 emission under AWD15 and AWD30 were 37.4–45.7% and 61.1–77.1% lower than FP, respectively. Multi-location on-farm comparisons were conducted in north, central, and southwest region of Guangdong province and the results confirmed that AWD15 could obtain comparable grain yield as FP with fewer irrigations. These findings suggested that the AWD15 could be used for water-saving and CH4 emission mitigation while maintaining grain yield in rice production in south China. This is the first report on the performance of safe AWD in south China.

A cotton field experiment was conducted to study the effects of plastic film mulching cultivation (PC) and non-mulching cultivation (NPC) on soil carbon content of an Aridisol, classified as a typic natrargid, in Xinjiang Uygher Autonomous Region, China. The use of PC enhanced the stock of soil organic carbon (SOC) at depths of 0–30 cm, but not at depths of 30–70 cm, compared with NPC. Furthermore, PC enhanced the stock of soil inorganic carbon (SIC) at depths of 30–70 cm but not at 0–30 cm. Overall, PC increased the total carbon (TC) stock at depths of 0–70 cm. The TC stock was higher in PC (16.37 kg C m− 2 year− 1) than in NPC (15.89 kg C m− 2 year− 1). The contribution percentage of SIC (52%) to the net soil carbon (C) accumulation was higher than that of SOC (48%). Our results suggested that adoption of PC could be used as an effective way to increase the carbon sequestration of soils under cotton systems in arid areas.

RpoS (σ(S)), the stationary phase/stress σ factor, controls the expression of a large number of genes involved in cellular responses to a variety of stresses. However, the role of RpoS appears to differ in different bacteria. While RpoS is an important regulator of flagellum biosynthesis, it is associated with biofilm development in Edwardsiella tarda. Biofilms are dense communities formed by bacteria and are important for microbe survival under unfavorable conditions. The type VI secretion system (T6SS) discovered recently is reportedly associated with several phenotypes, ranging from biofilm formation to stress sensing. For example, Vibrio anguillarum T6SS was proposed to serve as a sensor for extracytoplasmic signals and modulates RpoS expression and stress response. In this study, we investigated the physiological roles of RpoS in Yersinia pseudotuberculosis, including bacterial survival under stress conditions, flagella formation, biofilm development and T6SS expression. We found that RpoS is important in resistance to multiple stressors-including H2O2, acid, osmotic and heat shock-in Y. pseudotuberculosis. In addition, our study showed that RpoS not only modulates the expression of T6SS but also regulates flagellum formation by positively controlling the flagellar master regulatory gene flhDC, and affects the formation of biofilm on Caenorhabditis elegans by regulating the synthesis of exopolysaccharides. Taken together, these results show that RpoS plays a central role in cell fitness under several adverse conditions in Y. pseudotuberculosis.

Corynebacterium glutamicum can degrade phenol by a meta-cleavage pathway, which depends on ncgl2588 (phe) of the phe operon encoding phenol hydroxylase. An additional gene, ncgl2587 (pheR), is located upstream of phe. The pheR encodes an AraC/XylR-type regulator protein with 377 amino acid residues and is transcribed in the same direction as phe. Disruption of pheR by homologous recombination resulted in the accumulation of phenol in C. glutamicum. PheR demonstrates a low type of constitutive expression where phenol induces phe expression. PheR shares 75% sequence identity with AraC-type regulator of Corynebacterium lubricantis and 37 conserved residues, characteristic of AraC family, were located. A constructed pK18mobsacB-Pphe:lacZ transcriptional fusion plasmid was transformed into the wild-type, ΔpheR, and ΔpheR+ strains, and the results indicated that PheR activates the expression of phe encoding phenol hydroxylase. Electrophoretic mobility shift assay (EMSA) demonstrated a direct interaction of PheR with the phe promoter region and binding site of PheR on the Pphe was located 109-bp upstream of phe, as indicated by foot printing analysis. Our research provides deep insight into PheR expression and its regulatory function on Phe in C. glutamicum.

Nitrogen non-point pollution and greenhouse gas (GHG) emission are major challenges in rice production. This study examined options for both economic and environmental sustainability through optimizing water and N management. Field experiments were conducted to examine the crop yields, N use efficiency (NUE), greenhouse gas emissions, N losses under different N and water management. There were four treatments: zero N input with farmer's water management (N0), farmer's N and water management (FP), optimized N management with farmer's water management (OPTN) and optimized N management with alternate wetting and drying irrigation (OPTN + AWD). Grain yields in OPTN and OPTN + AWD treatments increased by 13.0–17.3% compared with FP. Ammonia volatilization (AV) was the primary pathway for N loss for all treatments and accounted for over 50% of the total losses. N losses mainly occurred before mid-tillering. N losses through AV, leaching and surface runoff in OPTN were reduced by 18.9–51.6% compared with FP. OPTN + AWD further reduced N losses from surface runoff and leaching by 39.1% and 6.2% in early rice season, and by 46.7% and 23.5% in late rice season, respectively, compared with OPTN. The CH4 emissions in OPTN + AWD were 20.4–45.4% lower than in OPTN and FP. Total global warming potential of CH4 and N2O was the lowest in OPTN + AWD. On-farm comparison confirmed that N loss through runoff in OPTN + AWD was reduced by over 40% as compared with FP. OPTN and OPTN + AWD significantly increased grain yield by 6.7–13.9%. These results indicated that optimizing water and N management can be a simple and effective approach for enhancing yield with reduced environmental footprints.

Optimized agronomic management improves nitrogen (N) use efficiency in crop production. However, limited information exists about the effect of improved agronomic practices on the N surplus in double rice cropping system. In this study, we conducted field experiments to evaluate the N surplus for the prevailing farmers’ practices (FP), optimized N management (OPTN) and optimized N and water management (OPTNW) during 2016–2017 in Guangdong province, South China. Grain yield, recovery efficiency (REN), partial factor productivity (PFPN) and agronomic efficiency (AE) of applied N in OPTN and OPTNW were substantially higher than FP. The yearly N surplus and environmental N loss in OPTN were 29.4% and 26.2% lower than FP, respectively. The N surplus in OPTNW was 32.1% lower than FP. Annual N losses resulting from runoff and leaching in OPTNW were reduced by 45.0% and 17.4%, respectively, compared with OPTN. Pooled data of 22 on-farm field trials from six sites in 2014–2017 showed that N input in OPTN and OPTNW was 16.2%–33.8% lower than FP. The tradable N output in OPTN and OPTNW was 9.9% and 9.0% greater than FP, respectively. The N efficiency of cropping systems (NUEc) in OPTN and OPTNW was increased by 39.8% and 42.0%, respectively, compared with FP. N surplus notably increased with the increasing fertilizer N input, and decreased with the increasing tradable N output and NUEc. These results suggest that through optimized N and irrigation management, N surplus and environmental risk can be practically reduced in a double rice cropping system without yield penalty.

To understand the genetic basis of nitrogen and phosphorus uptake in the cultivated rice, quantitative trait loci (QTL) analysis for 7 nitrogen and phosphorus uptake-related traits including above-ground biomass (AGB), leaf colour value (SPAD) in heading stage, grain nitrogen concentration (GNC), grain nitrogen content of the plant, total nitrogen content (TNC), grain phosphorus concentration, total phosphorus content (TPC) were conducted using SNP markers in a F2 population derived from a cross between GH128 and W6827. A total of 21 QTLs for nitrogen and phosphorus uptake-related traits distributed in 16 regions along 6 chromosomes were detected using a high density genetic map consisting of 1582 bin markers, with QTLs maximum explaining 8.19% of the phenotypic variation. Nine QTLs (42.9% of total QTLs) were detected on chromosome 2. Among them, two QTL clusters including AGB, TNC, TPC and GNC were also detected in the region bin 140 and bin 146 on the chromosome 2. The distance between the two clusters was only 4.1 cM. The presence of QTL clusters has important significance and could be useful in molecular marker assisted breeding. These genomic regions might be deployed for the simultaneous improving the use efficiency of nitrogen and phosphorus in rice breeding.

Diatoms, with hierarchical micro/nanoscale porous silica structures, have promising application in micro-nanotechnology especially biochemical sensing. In order to explore their potential and prepare diatom based substrates for biochemical sensor application, a fabrication technology for bonding diatom frustules and Si substrates was developed. The bonding process was carried out at 75 °C and assisted by hydrofluoric acid (HF). The bonding mechanism was discussed and several bonding conditions were adjusted to keep the morphological integrity of diatom frustules after bonding. The bonding pressure was optimized from 2.0 × 104 Pa to 3.0 × 104 Pa and the HF concentration from 0.4% to 0.6%. And the optimal shear bonding strength achieved was 0.72 MPa. In addition, bonded diatom frustules were further used as masks to obtain nano gold pillar arrays for surface-enhanced Raman scattering (SERS) detection.

We proved the feasibility of using a microfluidic chip to culture diatom Bacillaria paradoxa, and analyzed the gliding characteristics of its self-organized colony in detail. The optimal cultivation parameters of B. paradoxa for the designed chip made with polydimethylsiloxane are as follows: the preferable cells injecting rate for keeping the cells alive is 0.2 mL/h, the initial cell density for fast reproduction is 5.5 × 10(4) cells/mL, and the optimal replacement period of culture medium is 4 days. B. paradoxa tends to form a colony during their growth, and the colony can glide with a steady period of 29 ± 3 s along its axial direction in a constant stream, the amplitude of the colony will not decay (e.g., 24 μm of two-cell colony at 1.1 mm/s flow rate), and the colony rapidly adjusts its direction of gliding to the direction of water flow. The successful culture of diatoms on a microfluidic platform may be used for biosensing chips and the creation of gasoline-producing diatom solar panels.

Shark skin has attracted worldwide attention on its superior drag reduction, so-called shark skin effect. Such marvelous function of shark skin, in particular, is in part related to complicated micro-riblets. As the creation of natural evolution, micro-riblets of shark skin act out desirable drag reduction only within range of swimming speed. Over past few years, bio-replication approach which takes the shark skin as replica template to 1 : 1 transfer surface morphology has been widely applied for drag reduction. However, if application environment remarkably differs from living environment, the drag reduction function is attenuated or even becomes adverse, i.e., the surface structure nonadjustable to ambient environment is obstacle to widespread application of bio-replication. In this paper, large-scale equal-proportional amplification bio-replication approach is presented to adjust the micro-riblets of shark skin by taking solvent-swelling polymer as replica mould. Solvent-swelling property of polymer is investigated by controlling its swelling ratio to make natural surface function adapting to various application environment. Apart from higher replication accuracy about 95%, experiments show that about 140% solvent-swelling ratio is achieved at one-time amplification, and translation of drag reduction peak of natural surface function form living environment to various application environments is ensured by successive large-scale equal-proportional bio-replications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2383–2389, 2013

Aims: Eukaryotic typical 2-cysteine (Cys) peroxiredoxins (Prxs) are multifunctional proteins subjected to complex regulation and play important roles in oxidative stress resistance, hydrogen peroxide (H2O2) signaling modulation, aging, and cancer, but the information on the biochemical functions and regulation mechanisms of prokaryotic atypical 2-Cys Prxs is largely lacking. Results: In this study, we show that at low peroxide concentrations, the atypical 2-Cys Prx in Corynebacterium glutamicum (CgPrx) mainly exists as monomers and displays thioredoxin (Trx)-dependent peroxidase activity. Moderate oxidative stress causes reversible S-mycothiolation of the H2O2-sensing Cys63 residue, which keeps CgPrx exclusively in dimer form with neither peroxidase nor chaperone activity. Then, the increased levels of H2O2 could act as a messenger to oxidize the redox-sensitive regulator hydrogen peroxide-inducible gene activator, leading to activation of expression of the more efficient mycothiol peroxidase and...

Mycothiol (MSH) plays a major role in protecting cells against oxidative stress and detoxification from a broad range of exogenous toxic agents. In the present study, we reveal that intracellular MSH contributes significantly to the adaptation to acidic conditions in the model organism Corynebacterium glutamicum. We present evidence that MSH confers C. glutamicum with the ability to adapt to acidic conditions by maintaining pHi homeostasis, scavenging reactive oxygen species (ROS), and protecting methionine synthesis by the S-mycothiolation modification of methionine synthase (MetE). The role of MSH in acid adaptation was further confirmed by improving the acid tolerance of C. glutamicum by overexpressing the key MSH synthesis gene mshA. Hence, our work provides insights into a previously unknown, but important, aspect of the C. glutamicum cellular response to acid stress. The results reported here may help to understand acid tolerance mechanisms in acid sensitive bacteria and may open a new avenue for improving acid resistance in industry strains for the production of bio-based chemicals from renewable biomass.

Corynebacterium glutamicum can survive by using ferulic acid as the sole carbon source. In this study, we assessed the response of C. glutamicum to ferulic acid stress by means of a global transcriptional response analysis. The transcriptional data showed that several genes involved in degradation of ferulic acid were affected. Moreover, several genes related to the stress response; protein protection or degradation and DNA repair; replication, transcription and translation; and the cell envelope were differentially expressed. Deletion of the katA or sigE gene in C. glutamicum resulted in a decrease in cell viability under ferulic acid stress. These insights will facilitate further engineering of model industrial strains, with enhanced tolerance to ferulic acid to enable easy production of biofuels from lignocellulose.

A filtration-aided acid cleaning method was used to collect biosilica structures from a diatom culture medium, natural seawater, or water bloom. Cell extraction, acid cleaning, and acid removal were all performed on a polytetrafluoroethylene (PTFE) filter cloth, significantly improving the treatment capacity and efficiency of the traditional acid wash method. Five typical diatoms were cultivated in the laboratory for acid cleaning. Different growth speeds were introduced, and different process parameters for acid cleaning were utilized. After the acid cleaning, biosilica structures were collected from the frustules of diatoms using different methods. Girdle bands and valves of Coscinodiscus sp. were separated by floating of the valves. Central spines of Ditylum brightwellii and valves of Skeletonema costatum were separately collected by settling or filtration. Rod-like frustules, such as those of Bacillaris paradoxa, are not suitable for large quantities of acid wash. The silica structures were observed and tested using an AFM-calibrated glass needle to determine their elasticity. Elasticity tests showed that ringent girdle bands are more flexible than complete ones (Coscinodiscus sp.) and that both long-chain clusters of Nitzschia palea and central spines of D. brightwellii have certain elasticities. The required pressure for deforming or breaking the biosilica structures of diatoms was also determined.

Aims The improvement of nitrogen-deficiency tolerance (NDT) and nitrogen-use efficiency (NUE) traits is an important objective of many rice breeding programs. A better understanding of their relationship is required for more efficient breeding. The objectives of this study were to map quantitative trait loci (QTLs) for NDT and NUE traits, and to gain a better understanding about the genetic basis of the relationships between NUE and NDT traits.

In order to provide a scientific basis for developing integrated weed management strategies in rice paddy fields, this study investigated the influences of different types of fertilization on weed biodiversity. The experiment was conducted at Long-term-located Monitoring Station for Soil Fertility, Agricultural Science Academy, of Jiangxi Province, China. Five fertilization treatments were set: no fertilization (NOF), PK, NP, NK, and NPK. The results showed that the influence of different fertilization treatments on weed community traits followed the models PK > NOF > NK > NP > NPK for species richness, PK > NOF > NK > NP > NPK for species diversity, NPK > NP > NK > NOF > PK for community dominance, and PK > NOF > NK > NP > NPK for community evenness. Under NPK (i.e. balanced fertilization), the weed species diversity and richness and weed community evenness were the lowest. The principal component analysis showed that the weed community was divided into three groups: (i) NK and a part of NOF; (ii) NP and NPK; and (iii) PK and NOF. The correlation analysis indicated that the influence of each macro-element on the weed community followed the model N > P > K. The organic content in the paddy soil might have played an equally important role with the amount of available N in determining the weed community's characteristics. Regarding the way by which N, P, and K influenced the weed community, the amount of available P and K mainly influenced the organic content, while the amount of available N influenced both the organic content and light transmittance within the canopy, thereby enhancing the capacity of rice to compete with weeds.

Based on the fact that SiO2 can dissolve in HF solution, three kinds of diatom frustules were treated with 1% HF solution at room temperature. Given the proper reaction times (0–2 h for the diatoms Coscinodiscus and Navicula, and 0–3 h for the diatom Melosira), the size of the pores on the frustules gradually increased and the structures of the frustules remained. While HF treatment does not affect the composition, chemical bonds, or photoluminescence signature of the diatom frustules, the treatment reduces their surface areas. This method may be beneficial to diatom studies, diatom nanotechnology, and diatom device applications that make use of diatom pores.

Diatom valves and girdle bands are useful micro–nano materials in nanotechnology and micro manufacturing. A settling method is used to extract high-purity diatom valves and girdle bands from Coscinodiscus diatomite. The average models of diatom valves and girdle bands are established. Stokes Law and hydrokinetic theories are used to analyze the settling velocity of valves and girdle bands. Based on the calculation results, settling experiments are carried out, by which clean diatom valves with purity of 80% and girdle bands with purity of 90% are obtained. This method can be applied to other particles separation problem to separate micro-particles with similar radius but different sectional area.

With advantages of large capacity, long distance, low energy consumption, low cost, less land occupation and light pollution, inland waterway transportation becomes one of the most important constituents of the comprehensive transportation system and comprehensive water resources utilization in China. As one of “three elements” of navigation, waterway is the important basis for the development of water transportation and plays a key supporting role in shipping economic. The paper discuss how to realize the informatization and digitization of waterway management based on constructing an integrated system of standard inland electronic navigation chart production, waterway maintenance, navigation mark remote sensing and control, ship dynamic management, and water level remote sensing and report, which can also be the foundation of the intelligent waterway construction. Digital waterway construction is an information project and also has a practical meaning for waterway. It can not only meet the growing high assurance and security requirements for waterway, but also play a significant advantage in improving transport efficiency, reducing costs, promoting energy conservation and so on. This study lays a solid foundation on realizing intelligent waterway and building a smooth, efficient, safe, green modern inland waterway system, and must be considered as an unavoidable problem for the coordinated development between “low carbon” transportation and social economic.

A photoassisted chemical bonding method was used to accurately position diatom frustules into complex microscale patterns on a PDMS surface. The micropores and fine features of the diatom frustules...

Background Soil phosphorus (P) deficiency is one of the major limiting factors to crop production. The development of crop varieties with improved P use efficiency (PUE) is an important strategy for sustainable agriculture. The objectives of this research were to identify quantitative trait loci (QTLs) linked to PUE traits using a high-density single nucleotide polymorphism (SNP) map and to estimate the epistatic interactions and environmental effects in rice (Oryza sativa L.). Results We conducted a two-year field experiment under low and normal P conditions using a recombinant inbred population of rice derived from Zhenshan 97 and Minghui 63 (indica). We investigated three yield traits, biomass (BIOM), harvest index (HI), and grain yield (Yield), and eight PUE traits: total P uptake (PUP), P harvest index (PHI), grain P use efficiency (gPUE) based on P accumulation in grains, straw P use efficiency (strPUE) based on P accumulation in straw, P use efficiency for biomass (PUEb) and for grain yield (PUEg) based on P accumulation in the whole plant, P translocation (PT), and P translocation efficiency (PTE). Of the 36 QTLs and 24 epistatic interactions identified, 26 QTLs and 12 interactions were detected for PUE traits. The environment affected seven QTLs and three epistatic interactions. Four QTLs (qPHI1 and qPHI2 for PHI, qPUEg2 for PUEg, and qPTE8 for PTE) with strong effects were environmentally independent. By comparing our results with similar QTLs in previous studies, three QTLs for PUE traits (qPUP1 and qPUP10 for PUP, and qPHI6 for PHI) were found across various genetic backgrounds. Seven regions were shared by QTLs for yield and PUE traits. Conclusion Most QTLs linked to PUE traits were different from those linked to yield traits, suggesting different genetic controls underlying these two traits. Those chromosomal regions with large effects that are not affected by different environments are promising for improving P use efficiency. The seven regions shared by QTLs linked to yield and PUE traits imply the possibility of the simultaneous improvement of yield and PUE traits.

Weeding and fertilization are important farming practices. Integrated weed management should protect or improve the biodiversity of farmland weed communities for a better ecological environment with not only increased crop yield, but also reduced use of herbicides. This study hypothesized that appropriate fertilization would benefit both crop growth and the biodiversity of farmland weed communities. To study the effects of different fertilizing patterns on the biodiversity of a farmland weed community and their adaptive mechanisms, indices of species diversity and responses of weed species and wheat were investigated in a 17-year field trial with a winter wheat-soybean rotation. This long term field trial includes six fertilizing treatments with different N, P and K application rates. The results indicated that wheat and the four prevalent weed species (Galium aparine, Vicia sativa, Veronica persica and Geranium carolinianum) showed different responses to fertilizer treatment in terms of density, plant height, shoot biomass, and nutrient accumulations. Each individual weed population exhibited its own adaptive mechanisms, such as increased internode length for growth advantages and increased light interception. The PK treatment had higher density, shoot biomass, Shannon-Wiener and Pielou Indices of weed community than N plus P fertilizer treatments. The N1/2PK treatment showed the same weed species number as the PK treatment. It also showed higher Shannon-Wiener and Pielou Indices of the weed community, although it had a lower wheat yield than the NPK treatment. The negative effects of the N1/2PK treatment on wheat yield could be balanced by the simultaneous positive effects on weed communities, which are intermediate in terms of the effects on wheat and weeds.

Extreme weather conditions with negative impacts can strongly affect agricultural production. In the Danjiangkou reservoir area, citrus yields were greatly influenced by cold weather conditions and drought stress in 2011. Soil straw mulching (SM) practices have a major effect on soil water and thermal regimes. A two-year field experiment was conducted to evaluate whether the SM practices can help achieve favorable citrus fruit yields. Results showed that the annual total runoff was significantly (P

Diatom, with delicate nanoscale porous SiO 2 structures, has a promising application in biosensing. We bond diatoms with SiO 2 substrate using spin-on glass (SOG) as interlayer to acquire a high performance diatom based fluorescence detecting biosensor. As diatoms can improve proteins density, diatom based biosensors have higher sensitivity compared with traditional protein sensors. This biosensor is fully made of SiO 2 which can be modified for biomass attachment. Nanoscale structures of bonded diatoms are better preserved than any related works. The highest bonding strength is 0.6 MPa. Human immunoglobulin G (IgG) is attached on traditional protein sensors and diatom based biosensors as antibody. After hybridized with Cy3-goat anti-human IgG, the diatom based biosensor provides a fluorescence detection signal 2.5 times higher than the traditional one. Given improved fluorescence detecting sensitivity, this new kind of diatom based biosensor can be widely used for various protein detections.

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 μN in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates.

Recent years have witnessed the growing popularity of sensor and sensor-network technologies, supporting important practical applications. One of the fundamental issues is how to accurately locate a user with few labeled data in a wireless sensor network, where a major difficulty arises from the need to label large quantities of user location data, which in turn requires knowledge about the locations of signal transmitters or access points. To solve this problem, we have developed a novel machine learning-based approach that combines collaborative filtering with graph-based semi-supervised learning to learn both mobile users' locations and the locations of access points. Our framework exploits both labeled and unlabeled data from mobile devices and access points. In our two-phase solution, we first build a manifold-based model from a batch of labeled and unlabeled data in an offline training phase and then use a weighted k-nearest-neighbor method to localize a mobile client in an online localization phase. We extend the two-phase colocalization to an online and incremental model that can deal with labeled and unlabeled data that come sequentially and adapt to environmental changes. Finally, we embed an action model to the framework such that additional kinds of sensor signals can be utilized to further boost the performance of mobile tracking. Compared to other state-of-the-art systems, our framework has been shown to be more accurate while requiring less calibration effort in our experiments performed on three different testbeds.

Stem non-structural carbohydrates (NSCs) and its relationship with yield formation was investigated under low nitrogen (LN) and normal nitrogen (NN) treatments, using 46 recombinant inbred lines from Zhenshan 97 × Minghui 63 (Oryza sativa). Apparent contribution of transferred NSC to grain yield (AC(NSC) ) ranged from approximately 1 to 28% under LN and from 1 to 15% under NN. Concentration and total mass of NSC in stem (TM(NSC) ) at heading, apparent transferred mass of NSC (ATM(NSC) ) and AC(NSC) were larger under LN compared with NN. However, there was no significant difference in the apparent ratio of transferred NSC from stems to grain (AR(NSC) ). ATM(NSC) was positively correlated with grain yield, 1000-grain weight and AC(NSC) under both nitrogen levels, whereas AR(NSC) was highly correlated with harvest index and AC(NSC) . Leaf area contributed more strongly to grain yield compared with ATM(NSC) under both LN and NN. ATM(NSC) showed larger direct effects on grain yield under LN compared with NN. TM(NSC) at heading, small vascular bundles (SVBs) and spikelets per m(2) under LN had positive direct effects on ATM(NSC) . SVB and spikelets per m(2) under LN had larger and positive direct effects, and large vascular bundles had negative direct effects on AR(NSC) . TM(NSC) at heading and SVB under LN had positive direct effects on AC(NSC) . In brief, LN supply increased stem NSC accumulation and translocation to developing grain. Components of the source-sink-flow system showed different effects on NSC translocation and contribution to yield formation, depending on genotype and nitrogen level.

Diatom frustules exhibit various sophisticated shapes with highly ordered hierarchical porous nanostructures, which are promising for applications in the biomimetic fabrication of nanostructured materials. We propose a universal biopattern transfer process for the fabrication of functional micro/nanostructures using diatom frustules as the biotemplates. Porous silicon microcylinders with a thickness of 20 μm are fabricated by deep reactive ion etching of a silicon substrate, which is covered by a layer of diatom frustules. With a similar process, a fast atom beam technique is used to etch the silicon substrate and silicon nanolattices are obtained. By depositing a thin layer of gold film on the diatom bonded silicon substrate, followed by releasing the diatom frustules by diluted HF, gold nanodisks with a thickness of 30 nm are successfully fabricated. The nanodisk array arranges in diamond or radial patterns, replicating the nanostructure of diatom frustules. In addition, a parylene nanodot array is also demonstrated using this diatom-based biopattern transfer process.

Diatoms have delicate porous structures which are very beneficial in improving the absorbing ability in the bio-detection field. In this study, multi-layered hierarchical arrays were fabricated by packing Nitzschia soratensis (N. soratensis) frustules into Cosinodiscus argus (C. argus) frustules to achieve advanced sensitivity in bio-detection chips. Photolithographic patterning was used to obtain N. soratensis frustule arrays, and the floating behavior of C. argus frustules was employed to control their postures for packing N. soratensis frustule array spots. The morphology of the multi-layer C. argus–N. soratensis package array was investigated by scanning electron microscopy, demonstrating that the overall and sub-structures of the diatom frustules were retained. The signal enhancing effect of multi-layer C. argus–N. soratensis packages was demonstrated by fluorescent antibody test results. The mechanism of the enhancement was also analyzed, indicating that both complex hierarchical frustule structures and optimized posture of C. argus frustules were important for improving bio-detection sensitivities. The technique for fabricating multi-layer diatom frustules arrays is also useful for making multi-functional biochips and controllable drug delivery systems.

Sophisticated biomimetic microstructures/nanostructures have attracted attention worldwide, but their fabrication technique significantly restricts their application. This study uses natural sharkskin to investigate amplification (i.e., the bioscaling forming process) and thus acquire a complex microstructure that cannot be fabricated by traditional micromachining techniques. The bioscaling forming process adjusts the optimal function region of natural surfaces by utilizing the solvent-swelling effect of polydimethylsiloxane. To accurately replicate amplified sharkskin, the swelling ratio and rate in gaseous and liquid n-hexane were investigated. Epoxy resin was used to produce a positive sharkskin mold. A comparison between the microstructure of the original and amplified sharkskin shows that the swelling ratio can reach a maximum of 34% with gaseous n-hexane and 39% with liquid n-hexane. The accuracy of bioscaling forming was higher than 95%. The drag-reducing effect was also tested. When the sharkskin was amplified 1.34 times, the optimal velocity range of the drag reduction moved from 5.0 to 3.5 m s−1.

Diatom, with delicate three-dimensional porous structures and texture, has a promising application in micro-nanotechnology especially biosensing. In order to achieve a diatom-based compound substrate, a fabrication technique is developed for hydrofluoric acid (HF) bonding of diatom with SiO2-based substrate at a temperature as low as 80 °C. The bonding conditions are optimized with various HF concentrations and applied pressure. The optimized HF concentration is found to be in the range of 0.8% to 1.2% and applied pressure is from 0.4.0 MPa to 0.6.0 MPa. The morphological integrity and nano-microscale substructures of the diatoms after bonding are characterized. The bonding strength is approximately 0.435 MPa.

Diatom frustules, considered as novel bio-functional materials, display a diversity of patterns and unique micro- and nanostructures which may be useful in many areas of application. Existing devices directly use the original structure of the biosilica frustules, limiting their function and structural scale. Current research into the shapes, materials and structural properties of frustules are considered; a series of frustule processing methods including structure processing, material modification, bonding and assembly techniques are reviewed and discussed. The aim is to improve the function of diatom frustules allowing them to meet the design requirements of different types of micro devices. In addition, the importance of the comprehensive use of diatom processing methods in device research is discussed using biosensors and solar cells as examples, and the potential of bio-manufacturing technology based on diatom frustules is examined.