Improved High-Yield PMMA/Graphene Pressure Sensor and Sealed Gas Effect Analysis.

Graphene with atomic thickness possesses excellent mechanical and electrical properties, which hold great potential for high performance pressure sensing. The exposed electron of graphene is always cross-sensitive to any pollution absorbed or desorbed on the surface, from which the long-term stability of the graphene pressure sensor suffers a lot. This is one of the main obstacles towards graphene commercial applications. In this paper, we utilized polymethylmethacrylate (PMMA)/graphene heterostructure to isolate graphene from the ambient environment and enhance its strength simultaneously. PMMA/graphene pressure sensors, with the finite-depth cavity and the through-hole cavity separately, were made for comparative study. The through-hole device obtained a comparable sensitivity per unit area to the state of the art of the bare graphene pressure sensor, since there were no leaking cracks or defects. Both the sensitivity and stability of the through-hole sensor are better than those of the sensor with 285-nm-deep cavities, which is due to the sealed gas effect in the pressure cavity. A modified piezoresistive model was derived by considering the pressure change of the sealed gas in the pressure cavity. The calculated result of the new model is consistent with the experimental results. Our findings point out a promising route for performance optimization of graphene pressure sensors.

[The exploration of aerobic power and energy expenditure of Chinese rugby players].

OBJECTIVE: To explore aerobic power and energy expenditure of high level rugby players in China, which provide experimental basis for accurate training and nutritional strategy in match-play. METHODS: Eighteen master rugby players were selected as research subjects. The parameters such as VO2max, lactic aicd threshold (LT) and modify conconi test were measured respectively. The differences of energy were compared between the forward and the defender. The data were analyzed by independent sample t test. RESULTS: The VO2max(42.05±3.69 ml/min ·kg-1) of rugby players was poorer. The VO2max of the forward was 38.83±3.52 (ml/min ·kg-1), and that of the defender was 47.31±3.17 (ml/min ·kg-1),and there was significant difference between the forwards and the defenders (P＜0.05). The LT of the defenders was obviously higher than that of the forwards. Modifier conconi test had a high correlation (r = 0.772) with VO2max. The average energy consumption in the first half of the game was about(276.94±18.08)kcals, the second half was(225.58±22.86)kcals, and the second half was less than the first half (P＜0.05). CONCLUSION: The aerobic power is different between the forwards and the defenders. The power of aerobic of Chinese players is weaker than that of the foreign rugby players.

Dry transfer method for suspended graphene on lift-off-resist: simple ballistic devices with Fabry-Pérot interference.

We demonstrate a fabrication scheme for clean suspended structures using chemical-vapor-deposition-grown graphene and a dry transfer method on lift-off-resist-coated substrates to facilitate suspended graphene nanoelectronic devices for technological applications. It encompasses the demands for scalable fabrication as well as for ultra-fast response due to weak coupling to environment. The fabricated devices exhibited initially a weak field-effect response with substantial positive (p) doping which transformed into weak negative (n) doping upon current annealing at the temperature of 4 K. With increased annealing current, n-doping gradually decreased while the Dirac peak position approached zero in gate voltage. An ultra-low residual charge density of 9 × 108 cm-2 and a mobility of 1.9 × 105 cm2 V-1 s-1 were observed. Our samples display clear Fabry-Pérot (FP) conductance oscillation which indicates ballistic electron transport. The spacings of the FP oscillations are found to depend on the charge density in a manner that agrees with theoretical modeling based on Klein tunneling of Dirac particles. The ultra-low residual charge, the FP oscillations with density dependent period, and the high mobility prove the excellent quality of our suspended graphene devices. Owing to its simplicity, scalability and robustness, this fabrication scheme enhances possibilities for production of suspended, high-quality, two-dimensional-material structures for novel electronic applications.

RNA-SEQ Reveals Transcriptional Level Changes of Poplar Roots in Different Forms of Nitrogen Treatments.

Poplar has emerged as a model plant for better understanding cellular and molecular changes accompanying tree growth, development, and response to environment. Long-term application of different forms of nitrogen (such as [Formula: see text]-N and [Formula: see text]-N) may cause morphological changes of poplar roots; however, the molecular level changes are still not well-known. In this study, we analyzed the expression profiling of poplar roots treated by three forms of nitrogen: S1 ([Formula: see text]), S2 (NH4NO3), and S3 ([Formula: see text]) by using RNA-SEQ technique. We found 463 genes significantly differentially expressed in roots by different N treatments, of which a total of 112 genes were found to differentially express between S1 and S2, 171 genes between S2 and S3, and 319 genes between S1 and S3. A cluster analysis shows significant difference in many transcription factor families and functional genes family under different N forms. Through an analysis of Mapman metabolic pathway, we found that the significantly differentially expressed genes are associated with fermentation, glycolysis, and tricarboxylic acid cycle (TCA), secondary metabolism, hormone metabolism, and transport processing. Interestingly, we did not find significantly differentially expressed genes in N metabolism pathway, mitochondrial electron transport/ATP synthesis and mineral nutrition. We also found abundant candidate genes (20 transcription factors and 30 functional genes) regulating morphology changes of poplar roots under the three N forms. The results obtained are beneficial to a better understanding of the potential molecular and cellular mechanisms regulating root morphology changes under different N treatments.

Differential expression of copper-zinc superoxide dismutase gene of Polygonum sibiricum leaves, stems and underground stems, subjected to high-salt stress.

In aerobic organisms, protection against oxidative damage involves the combined action of highly specialized antioxidant enzymes, such as copper-zinc superoxide dismutase. In this work, a cDNA clone which encodes a copper-zinc superoxide dismutase gene, named PS-CuZnSOD, has been identified from P. sibiricum Laxm. by the rapid amplification of cDNA ends method (RACE). Analysis of the nucleotide sequence reveals that the PS-CuZnSOD gene cDNA clone consists of 669 bp, containing 87 bp in the 5' untranslated region; 459 bp in the open reading frame (ORF) encoding 152 amino acids; and 123 bp in 3' untranslated region. The gene accession nucleotide sequence number in GenBank is GQ472846. Sequence analysis indicates that the protein, like most plant superoxide dismutases (SOD), includes two conserved ecCuZnSOD signatures that are from the amino acids 43 to 51, and from the amino acids 137 to 148, and it has a signal peptide extension in the front of the N-terminus (1-16 aa). Expression analysis by real-time quantitative PCR reveals that the PS-CuZnSOD gene is expressed in leaves, stems and underground stems. PS-CuZnSOD gene expression can be induced by 3% NaHCO(3). The different mRNA levels' expression of PS-CuZnSOD show the gene's different expression modes in leaves, stems and underground stems under the salinity-alkalinity stress.

[Analysis of cDNA library of Cucumis sativus L. challenged by Pseudomonas syringae pv. Lachrymans].

A cDNA library was constructed from the leaves of the disease-resistant cucumber (Cucumis sativus L.) cultivar 'D0462' challenged by Pseudomonas syringae pv. Lachrymans for 48 h. The inserted fragment sizes ranged from 0.45 to 2.1 kb and the average inserted size was 1 kb. Sequencing analysis showed that 2 352 TUTs (Tentative unique transcripts), 282 contigs, and 2 070 singlets were identified in the 2 966 ESTs derived from the cDNA library. The result of the BlastX analysis indicated that there were 1 848 ESTs with known or unknown function, 504 ESTs with no significant similarity matching with any protein or DNA sequence in the databases. In this library, many defense/disease-resistant related genes, such as metallothionein, glutathione S-transferase, ubiquitin, b-1, 3-glucanase, zinc finger protein, and cysteine protease, which might participate in the plant and the pathogens, are inclued.

Label-free quantitative proteomics analysis of etiolated maize seedling leaves during greening.

To better understand light regulation of C(4) plant maize development, we investigated dynamic proteomic differences between green seedlings (control), etiolated seedlings, and etiolated seedlings illuminated for 6 or 12 h using a label-free quantitative proteomics approach based on nanoscale ultraperformance liquid chromatography-ESI-MS(E). Among more than 400 proteins identified, 73 were significantly altered during etiolated maize seedling greening. Of these 73 proteins, 25 were identified as membrane proteins that seldom had been identified with two-dimensional electrophoresis methods, indicating the power of our label-free method for membrane protein identification; 31 were related to light reactions of chlorophyll biosynthesis, photosynthesis, and photosynthetic carbon assimilation. The expression of photosystem II subunits was highly sensitive to light; most of them were not identified in etiolated maize seedlings but drastically increased upon light exposure, indicating that the complex process of biogenesis of the photosynthetic apparatus correlates with the transition from a dark-grown to a light-grown morphology. However, transcriptional analysis indicated that most transcripts encoding these proteins were not regulated by light. In contrast, the levels of mRNAs and proteins for enzymes involved in carbon assimilation were tightly regulated by light. Additionally phosphoenolpyruvate carboxykinase, the key enzyme of the phosphoenolpyruvate carboxykinase C(4) pathway, was more tightly regulated by light than the key enzymes of the NADP-malic enzyme C(4) pathway. Furthermore phosphoenolpyruvate carboxylase 1C, which was originally reported to be specifically expressed in roots, was also identified in this study; expression of this enzyme was more sensitive to light than its isoforms. Taken together, these results represent a comprehensive dynamic protein profile and light-regulated network of C(4) plants for etiolated seedling greening and provide a basis for further study of the mechanism of gene function and regulation in light-induced development of C(4) plants.

[Construction and analysis of a forward and reverse subtractive cDNA library from leaves and stem of Polygonum sibiricum Laxm. under salt stress].

Using cDNAs prepared from the leaves and stems of Polygonum sibiricum Laxm. treated with NaHCO3 stress for 48 h as testers and cDNAs from unstressed P. sibiricum leaves and stems as drivers library, suppression subtractive hybridization (SSH) was employed to construct a cDNA subtracted library, which contained 2 282 valid sequences including 598 ESTs in the stems forward SSH library and 490 ESTs in the stem reverse SSH library, 627 ESTs in the leaf forward SSH library and 567 in the leaf reverse SSH library. According to the functional catalogue of MIPs and the comparison of the reverse and forward SSH libraries of the stem and leaf, the responses to NaHCO3 stress were different between leaf and stem, except for the same trend in cell rescue defense and transport facilitation. The trend in the metabolism, energy, photosynthesis, protein synthesis, transcription, and signal transduction was opposite. RT-PCR analysis demonstrated that the expression of 12 putative stress related genes in the NaHCO3-treated leaves and stems was different from that in the untreated leaves and stems. This indicated that different mechanisms might be responsible for reactions of leaf and stem in P. sibiricum. The results from this study are useful in understanding the molecular mechanism of saline-alkali tolerance in P. sibiricum.

[Cloning of PsPIP1 gene from Polygonum sibiricum Laxm. and analy-sis of its expression in response to NaHCO3].

Gene PsPIP1 (GenBank accession No. EU626398) containing a complete ORF was obtained using rapid amplification of cDNA ends (RACE) from the cDNA library of Polygonum sibiricum Laxm. leaves. The length of cDNA was 1 004 bp, which encoded a peptide of 285 amino acid residues. Based on other kinds of plant aquaporin amino acid sequences, the phylogenetic evolution, and tertiary structure of protein comparison, this gene was classified into aquaporin subfamily. Expression analysis by Real-time PCR showed that PsPIP1 gene was expressed in leaves, stems, and underground stems. The expression level of PsPIP1 gene was higher in leaves than in underground stems and was the lowest in stems. The expression pattern of PsPIP1 gene induced by NaHCO3 stress and de-stressing also varied remarkably.

[Cloning and expression of cysteine synthase gene from Polygonum sibiricum Laxm.].

Cysteine synthase is a key enzyme for restricting plant cysteine synthesis. Cysteine synthase gene, designated PcCSase1 (GenBank accession no. EU597481), was successfully isolated from Polygonum sibiricum Laxm. by RACE technique. This gene was 1 260 bp in full-length and encoded a peptide of 382 amino acids. Based on bioinformatic analysis, PcCSase1 is a cytoplasm cysteine synthesis and contains a 16 amino-terminal (N-terminal) signal peptide, which led the PcCSase1 to go to the cytoplasm. The results obtained through homologous sequence analysis indicated that PcCSase1 mature protein was highly conserved in plants, which shared approximate 90% in the amino acid sequence. Expression analysis by RT-PCR showed that PcCSase1 gene was expressed in leaf, stem and root with the largest expression in leaf. Under 3% NaHCO3 stress, the largest expression of PcCSase1 gene was detected in leaf, stem and root at the second day following stress. PcCSase1 gene was inserted into pYES2 and transformed into yeast cells (Saccharomyces cerevisiae). The contents of the glutathione in the recombinant yeast and the cysteine in the medium were increased. INVSc1-pYES2-PcCSase1 was more tolerant to salt treatment than INVSc1-pYES2 and the former survival rate was higher than that of the later under the stress of 10% NaHCO3 and 5 mol/L NaCl. These results proved that PcCSase1 gene may confer high salt-tolerance.

A shotgun phosphoproteomics analysis of embryos in germinated maize seeds.

To better understand the role that reversible protein phosphorylation plays in seed germination, we initiated a phosphoproteomic investigation of embryos of germinated maize seeds. A total of 776 proteins including 39 kinases, 16 phosphatases, and 33 phosphoproteins containing 36 precise in vivo phosphorylation sites were identified. All the phosphorylation sites identified, with the exception of the phosphorylation site on HSP22, have not been reported previously (Lund et al. in J Biol Chem, 276, 29924-29929, 2001). Assayed with QRT-PCR, the transcripts of ten kinase genes were found to be dramatically up-regulated during seed germination and those of four phosphatase genes were up-regulated after germination, which indicated that reversible protein phosphorylation occurred and complex regulating networks were activated during this period. At least one-third of these phosphoproteins are key components involved in biological processes which relate to seed germination, such as DNA repair, gene transcription, RNA splicing and protein translation, suggesting that protein phosphorylation plays an important role in seed germination. As far as we know, this is the first phosphoproteomic study on a monocot and it will lay a solid foundation for further study of the molecular mechanisms of seed germination and seedling development.