Effect of temperature on galvanic corrosion of Al 6061-SS 304 in nitric acid

Nitrogen tetroxide (N2O4) is commonly used as an oxidizer for bipropellant liquid, and galvanic corrosion of its storage tanks was a serious problem. The immersion and electrochemical experiments of Al 6061-SS 304 galvanic pair were carried out in 30% nitric acid at different temperatures. The accelerated galvanic corrosion of Al 6061 and the effect of different temperatures on its corrosion behavior were studied. The surface morphology, number of corrosion pits and electrochemical parameters of Al 6061 before and after corrosion were measured and analyzed by means of SEM, EDS and electrochemical methods. The results show that when Al 6061 was coupled with SS 304 at 10 °C, the driving potential difference between them reached 366 mVSCE, and Al 6061 was used as the corrosion anode. In the SEM images, three kinds of galvanic corrosion phenomena can be seen obviously after coupling. When the temperature is between 10 °C and 30 °C, the corrosion pits are mainly composed of aluminum matrix coupled with second phase particles with positive or negative volt potential relative to it. When the temperature was between 40 °C and 50 °C, the corrosion pits showed mainly intergranular corrosion at the interface of different grains. At the same time, the increase in temperature led to the decrease in galvanic potential and the change in corrosion current. There was no simple linear relationship between galvanic current and temperature, but it satisfied a certain quantitative relationship, and the theoretical ratio was highly consistent with the actual ratio by the K–S test

The ATP-binding cassette (ABC) transporter OsABCG3 is essential for pollen development in rice

Abstract Background The pollen wall, which protects male gametophyte against various stresses and facilitates pollination, is essential for successful reproduction in flowering plants. The pollen wall consists of gametophyte-derived intine and sporophyte-derived exine. From outside to inside of exine are tectum, bacula, nexine I and nexine II layers. How these structural layers are formed has been under extensive studies, but the molecular mechanisms remain obscure. Results Here we identified two osabcg3 allelic mutants and demonstrated that OsABCG3 was required for pollen development in rice. OsABCG3 encodes a half-size ABCG transporter localized on the plasma membrane. It was mainly expressed in anther when exine started to form. Loss-function of OsABCG3 caused abnormal degradation of the tapetum. The mutant pollen lacked the nexine II and intine layers, and shriveled without cytoplasm. The expression of some genes required for pollen wall formation was examined in osabcg3 mutants. The mutation did not alter the expression of the regulatory genes and lipid metabolism genes, but altered the expression of lipid transport genes. Conclusions Base on the genetic and cytological analyses, OsABCG3 was proposed to transport the tapetum-produced materials essential for pollen wall formation. This study provided a new perspective to the genetic regulation of pollen wall development

Reduced contrast sensitivity function correlated with superficial retinal capillary plexus impairment in early stage of dysthyroid optic neuropathy

Abstract Background To assess the accuracy of contrast sensitivity function (CSF) in detecting dysthyroid optic neuropathy (DON) at an early stage in thyroid-associated ophthalmopathy (TAO) patients and to examine potential factors that may be linked to early visual impairments in these individuals. Methods A total of 81 TAO patients (50 non-DON and 31 DON), and 24 control subjects participated in the study. CSF was measured with the quick CSF (qCSF) method. Optical coherence tomography angiography (OCTA) images of the ganglion cell complex layer (GCCL), superficial and deep retinal capillary plexuses (SRCP and DRCP) in a 3 mm diameter area around the macula were evaluated. Results Compared with the controls, the area under the log contrast sensitivity function (AULCSF) and SRCP density were significantly reduced in non-DON and DON patients (all P < 0.05). The GCCL thickness of the DON patients was thinner than that of the controls and non-DON patients (all P < 0.05). The AULCSF was significantly correlated with spherical equivalent refractive error, muscle index, SRCP density and GCCL thickness in TAO patients, respectively (all P < 0.05). However, stepwise multi-regression analysis showed that the AULCSF was only significantly correlated with SRCP density (P < 0.001). Receiver operating characteristic curve analysis showed that the AULCSF produced the most accurate discrimination between non-DON and DON patients from the controls (AUC = 0.831, 0.987, respectively; all P < 0.001). Conclusions CSF change in the early stage of DON is related to SRCP density. It can be an early indicator of visual impairments associated with DON in TAO patients

<em>Ehd4</em> Encodes a Novel and <em>Oryza</em>-Genus-Specific Regulator of Photoperiodic Flowering in Rice

<div><p>Land plants have evolved increasingly complex regulatory modes of their flowering time (or heading date in crops). Rice (<i>Oryza sativa</i> L.) is a short-day plant that flowers more rapidly in short-day but delays under long-day conditions. Previous studies have shown that the <i>CO</i>-<i>FT</i> module initially identified in long-day plants (Arabidopsis) is evolutionary conserved in short-day plants (<i>Hd1</i>-<i>Hd3a</i> in rice). However, in rice, there is a unique <i>Ehd1</i>-dependent flowering pathway that is <i>Hd1</i>-independent. Here, we report isolation and characterization of a positive regulator of <i>Ehd1</i>, <i>Early heading date 4</i> (<i>Ehd4</i>). <i>ehd4</i> mutants showed a never flowering phenotype under natural long-day conditions. Map-based cloning revealed that <i>Ehd4</i> encodes a novel CCCH-type zinc finger protein, which is localized to the nucleus and is able to bind to nucleic acids <i>in vitro</i> and transactivate transcription in yeast, suggesting that it likely functions as a transcriptional regulator. <i>Ehd4</i> expression is most active in young leaves with a diurnal expression pattern similar to that of <i>Ehd1</i> under both short-day and long-day conditions. We show that <i>Ehd4</i> up-regulates the expression of the “florigen” genes <i>Hd3a</i> and <i>RFT1</i> through <i>Ehd1,</i> but it acts independently of other known <i>Ehd1</i> regulators. Strikingly, <i>Ehd4</i> is highly conserved in the <i>Oryza</i> genus including wild and cultivated rice, but has no homologs in other species, suggesting that <i>Ehd4</i> is originated along with the diversification of the <i>Oryza</i> genus from the grass family during evolution. We conclude that <i>Ehd4</i> is a novel <i>Oryza</i>-genus-specific regulator of <i>Ehd1</i>, and it plays an essential role in photoperiodic control of flowering time in rice.</p> </div

Map-based cloning of <i>Ehd4</i>.

<p>(<i>A</i>) Location of the <i>Ehd4</i> locus on rice chromosome 3. (<i>B</i>) High-resolution linkage map of <i>Ehd4</i>. (<i>C</i>) Candidate genes on BAC OSJNBb0005F16. (<i>D</i>) Structure of the <i>Ehd4</i> gene. Lines, black and white boxes represent introns, exons and untranslated regions, respectively. The base change from G to A creates an early stop codon (Asterisk). (<i>E</i>) Complementation of <i>ehd4</i>. <i>Ehd4</i> was driven by either the native promoter (<i>pEhd4::Ehd4</i>) or the maize <i>Ubiquitin-1</i> promoter (<i>pUbi::Ehd4</i>). T2 plants of two <i>pEhd4::Ehd4</i> lines (#26 and #34) and two <i>pUbi::Ehd4</i> lines (#18 and #24) were measured (<i>n</i> = 10). All plants were grown under both SD and LD conditions.</p

Natural variations in the <i>Ehd4</i> coding region among rice germplasm core collection.

<p>(<i>A</i>) Haplotype network of the <i>Ehd4</i> alleles in 86 rice accessions. Haplotype frequencies are proportional to the area of the circles. The proportion of wild rice and two cultivated subgroups (<i>indica</i> and <i>japonica</i>) in each haplotype is represented by different colors. (<i>B</i>) The polymorphic nucleotides of Hap_2 and Hap_3 of <i>Ehd4</i> gene in the core collection. The number on the top shows the position of nucleotide polymorphisms in the coding region starting from the ATG start codon. (<i>C</i>) Geographic distribution of the cultivated rice accessions belonging to Hap_2 and Hap_3. (<i>D</i>) Flowering time of transgenic plants carrying two major haplotypes of <i>Ehd4</i> driven by the maize <i>Ubiquitin-1</i> promoter in <i>ehd4</i> (Kita-ake background) and NIL carrying <i>Ehd4</i>^Hap3 compared with the 93-11 parental plants. T2 plants of two <i>pUbi::Ehd4</i>^Hap3 (#18 and #24) and two <i>pUbi::Ehd4</i>^Hap2 (#12 and #16) lines were measured (<i>n</i> = 15). All plants were grown in the natural long day field conditions. Values are means±s.d. (standard deviations) (<i>n</i> = 15). **Significant at 1% level; <i>n.s.</i>, not significant.</p

EHD4 is a nuclear protein with intrinsic transcriptional activation and nucleic acid binding activities.

<p>(<i>A</i>) Sub-cellular localization of EHD4-GFP fusion protein. (<i>B</i>) The nuclear marker MADS3-mCherry fusion protein. (<i>C</i>) Merged image of (<i>A</i>) and (<i>B</i>) under bright field. Scale bar = 10 µm in (<i>A</i>) to (<i>C</i>). (<i>D</i>) Transactivation assays of EHD4 and its deletion derivatives in the yeast GAL4 system. Full length EHD4 and several deletion derivatives of EHD4 (pEhd4-Δ, pEhd4-N and pEhd4-CΔ) were used in assays. The empty vector (BD-MCS) and BD-DST <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003281#pgen.1003281-Huang1" target="_blank">[56]</a> were used as negative and positive control, respectively. Transformants were dropped onto SD/Trp- and SD/His- plates to allow growth of 48 hours before taking pictures. Values in β-galactosidase activity are means of three independent experiments. Bars stand for standard deviations. BD, DNA-binding domain of GAL4. (<i>E</i>) The CCCH motif is essential for binding to nucleic acids. C terminal, N terminal or C terminal without CCCH motif of EHD4 was expressed in <i>E</i>.<i>coli</i> and purified for binding assays. Deletion of the CCCH motif abolished the binding to ribohomopolymers and both double- and single-stranded calf thymus DNA.</p

Expression pattern of <i>Ehd4</i>.

<p>(<i>A</i>) 30-d old wild-type plants (Kita-ake) grown under SDs were used for quantitative RT-PCR. DL1, newly emerging leaf; DL2, expending leaf; DL3, fully expended leaf; ASA, around the shoot apex. (<i>B</i>) <i>Ehd4</i> transcript levels in various organs (means±s.d, <i>n</i> = 3). (<i>C</i>) to (<i>I</i>) GUS staining of various organs in <i>pEHD4::GUS</i> transgenic plants. (<i>C</i>) Root; (<i>D</i>) Floret; (<i>E</i>) Stem; (<i>F</i>) to (<i>H</i>) Transverse sections of stem, immature leaf and sheath, respectively; (<i>I</i>) Longitudinal section of the shoot apical meristem (SAM). Arrow indicates phloem in (<i>F</i>) and (<i>G</i>) and SAM in (<i>I</i>). (<i>J</i>) and (<i>K</i>) Rhythmic and developmental expression of <i>Ehd4</i>. The rice <i>Ubiquitin-1</i> (<i>UBQ</i>) gene was used as the internal control. Values are shown as mean±s.d of three independent experiments and two biological replicates. The open and filled bars at the bottom represent the light and dark periods, respectively. s.d: standard deviations.</p

The rhythmic expression pattern of <i>Hd3a</i>, <i>RFT1</i>, and <i>Ehd1</i>, but not <i>Hd1</i>, was abolished in the <i>ehd4</i> mutant plants under both SDs and LDs.

<p>SDs (<i>A</i>, <i>C</i>, <i>E</i> and <i>G</i>); LDs (<i>B</i>, <i>D</i>, <i>F</i> and <i>H</i>). The open and filled bars at the bottom represent the light and dark periods, respectively. The rice <i>Ubiquitin-1</i> (<i>UBQ</i>) gene was used as the internal control. Values are shown as mean±s.d. (standard deviations) of three independent experiments and two biological replicates.</p