Effect of Hydrogen Addition on Soot Formation and Emission in Acetylene Laminar Diffusion Flame

Hydrogen (H₂) has been regarded as a highly competitive alternative fuel that does not produce CO₂ and soot during combustion. There are few studies of cofiring H₂ with hydrocarbons. Meanwhile, the effect of hydrogen addition on soot formation and emission is questionable. In this study, the effect of H₂ addition with varying ratios (between 0 and 50% by molar fraction while the remainder is nitrogen) on soot formation in acetylene (50% by molar fraction) laminar diffusion flames was experimentally and numerically investigated. Results show that with H₂ addition, the flame height increases and the temperature decreases. The total soot emission and the primary particle size both increase with H₂ addition. The addition of H₂ promotes soot formation. In addition, the soot oxidation is weakened due to the lower flame temperature. Chemical kinetic analysis shows that the concentrations of A1, H, and H₂O increase with H₂ addition, which is consistent with the experimental results. According to the HACA reaction, the increase of the molar fraction of A1 and H radicals could promote PAH growth and soot formation.

Long-term effects of phytoextraction by a poplar clone on the concentration, fractionation, and transportation of heavy metals in mine tailings

Mine tailings are one of main causes of diffused heavy metal pollution since the heavy metals in there may acquire mobility. The current knowledge of the processes at work in long-term phytoremediation by woody species remains insufficient. Through a 4-year field study, we evaluated the phytoextraction efficiency of Populus deltoides CL. 'Xianglin 90' grown on a mine tailing co-polluted by Cd, Cu, Cr, Ni, Pb, and Zn. The concentrations of Cd, Cu, Ni, Pb, and Zn in the rhizospheric soil were reduced by amounts ranging from 12.86 to 42.19% during the study period. Bioconcentration factors and translocation factors showed that the accumulation of Cd and Zn occurring in the shoots was the most effective. Combined with the considerable biomass produced by poplar, the extracted amounts of Cd and Zn could reach 0.61 g and 10.66 g plant^-1, respectively, in which the shoots account for 77.3% (Cd) and 89.0% (Zn) of the overall extraction amounts. Acid-soluble Cd and Zn increased by 5.49% and 4.29%, respectively, in the rhizosphere compared to the bulk soil, indicating that poplar enhanced the mobility of Cd and Zn in the rhizosphere, which explained its ability for bioaccumulation and root-shoot translocation. Moreover, calculated time required to address the issue of Cd and Zn pollution was theoretically shortened by more than half from 2015 to 2019. This study brings new insights into the long-term effects of phytoextraction on the concentration, fractionation, and transportation of heavy metals and confirms the potential of poplar as a Cd and Zn remediation species.

P1890Pioglitazone inhibits diabetes-induced atrial mitochondrial oxidative stress and improves mitochondrial biogenesis, dynamics and function through the PGC-1 signaling pathway

Background

Oxidative stress contributes to adverse atrial remodeling in diabetes mellitus. This can be prevented by the PPAR-γ agonist pioglitazone through its anti-oxidant and anti-inflammatory effects.

Purpose

In this study, the molecular mechanisms underlying these effects were investigated.

Methods

Rabbits were randomly divided into control (C), diabetic (DM), and pioglitazone-treated DM (Pio) groups. Echocardiographic, hemodynamic, electrophysiological, intracellular Ca2+ properties were measured. Serum PPAR-γ levels, serum and tissue oxidative stress and inflammatory markers, mitochondrial morphology, reactive oxygen species (ROS) production rate, respiratory function, and mitochondrial membrane potential (MMP) levels were measured. Protein expression of pro-fibrotic marker transforming growth factor β1 (TGF-β1), and the mitochondrial proteins (PGC-1α, fission and fusion-related proteins) were measured.

Results

Compared with controls, the DM group demonstrated larger left atrial diameter and fibrosis area associated with a higher incidence of inducible AF. Lower serum PPAR-γ level was associated with lower PGC-1α, higher NF-κB and higher TGF-β1 expression. Mn-SOD protein was not different but lower mitochondrial fission- and fusion-related proteins were detected. Mitochondrial swelling, higher mitochondrial ROS, lower respiratory control rate, lower MMP and higher intracellular Ca2+ transients were observed. In the Pio group, reversal of structural remodeling and lower inducible AF incidence were associated with higher PPAR-γ and PGC-1α. NF-κB and TGF-β1 were lower and biogenesis, fission and fusion-related protein were higher. Mitochondrial structure and function, and intracellular Ca2+ transients were improved. In HL-1 cell line, transfected with PGC-1α siRNA blunted the effect of pioglitazone on Mn-SOD protein expression and MMP collapse in H2O2-treated cells.

Conclusion

Diabetes mellitus induces adverse atrial structural and electrophysiological remodeling, abnormal Ca2+ handling and mitochondrial damage and dysfunction. Pioglitazone prevented these abnormalities through the PPAR-γ/PGC-1α pathway.

Acknowledgement/Funding

National Natural Science Foundation of China (No 81570298, 81270245, 30900618 to T.L.)

Electrochemical exfoliation of ultrathin ternary molybdenum sulfoselenide nanosheets to boost the energy-efficient hydrogen evolution reaction

Developing low-cost and highly efficient transition metal dichalcogenides as alternative electrocatalysts has become an urgent need for the hydrogen evolution reaction (HER). However, the inert basal planes of transition metal dichalcogenides severely suppress their practical applications. Herein, we developed ultrathin ternary molybdenum sulfoselenide (MoSe_xS_2-x) nanosheets by using the cathodic electrochemical exfoliation approach in non-aqueous electrolytes. The exfoliated MoSe_xS_2-x nanosheets demonstrated high structural integrity with lateral dimensions up to ∼1.5 μm and an average thickness of about 3 nm. Owing to the unique ultrathin structure and immensely exposed active sites, the ternary MoSe_xS_2-x nanosheets supported on Ni foam demonstrated a greatly enhanced electrocatalytic activity for the HER in 1.0 M KOH with an overpotential of 123 mV at a current density of 10 mA cm^-2 and high stability, superior to majority of the previously published MoS₂-based electrocatalysts. Furthermore, the ternary MoSe_xS_2-x nanosheets as a highly active bifunctional electrocatalyst contributed to enhanced energy-efficient hydrogen production and electrocatalytic synthesis of ammonia.

Scalable Production of Few-Layer Niobium Disulfide Nanosheets via Electrochemical Exfoliation for Energy-Efficient Hydrogen Evolution Reaction

Two-dimensional (2D) niobium disulfide (NbS₂) materials feature unique physical and chemical properties leading to highly promising energy conversion applications. Herein, we developed a robust synthesis technique consisting of electrochemical exfoliation under alternating currents and subsequent liquid-phase exfoliation to prepare highly uniform few-layer NbS₂ nanosheets. The obtained few-layer NbS₂ material has a 2D nanosheet structure with an ultrathin thickness of ∼3 nm and a lateral size of ∼2 μm. Benefiting from their unique 2D structure and highly exposed active sites, the few-layer NbS₂ nanosheets drop-casted on carbon paper exhibited excellent catalytic activity for the hydrogen evolution reaction (HER) in acid with an overpotential of 90 mV at a current density of 10 mA cm^-2 and a low Tafel slope of 83 mV dec^-1, which are superior to those reported for other NbS₂-based HER electrocatalysts. Furthermore, few-layer NbS₂ nanosheets are effective as bifunctional electrocatalysts for hydrogen production by overall water splitting, where the urea and hydrazine oxidation reactions replace the oxygen evolution reaction.

A first-principles study of CO oxidation by surface oxygen on Pt-incorporated perovskite catalyst (CaPtxTi1−xO3)

In the present work, we investigated the structural and catalytic properties of a prototype system Pt-doped CaTiO₃ by means of first principles calculations.

Regulation of nucleocytoplasmic localizatioin of the atDjC6 chaperone protein

The sequence of the atDjC6 chaperone protein includes three potential nuclear localization signal (NLS) sequences (A-C) and three potential nuclear export signal (NES) sequences (X-Z). The subcellular localization of atDjC6 was studied by scanning laser confocal microscopy of chimera with the green-fluorescent protein (GFP) transiently expressed in tobacco BY-2 cells. The localization of the atDjC6::GFP chimera was coincident with that of the nuclear stain propidium iodide. Site-directed mutagenesis was used to verify the predicted NLS sequences. Each was individually fused to GFP and tested for protein localization. The individual NLS sequences were sufficient to direct partial nuclear localization of GFP, although the targeting information within NLS-B is apparently conformation sensitive. Site-directed mutagenesis of the NES sequences increased the amount of each chimera that was nuclearly localized, indicating a decrease in nuclear export. When any pair of NLS sequences were appended to GFP, the chimera were entirely nuclearly localized. Quantitative two-hybrid analysis was used to verify that the decoding of NLS sequence information involves interaction with the NLS-receptor protein importin-alpha. Each of the NLS sequences is flanked by a site of potential Ser phosphorylation, and recombinant atDjC6 could be phosphorylated in vitro. Mutagenesis of Ser residues to the P-Ser mimic Asp interfered with nuclear targeting, apparently by preventing recognition or binding by importin-alpha. Our results are consistent with a regulated nucleocytoplasmic localization of the atDjC6 chaperone protein.

[Inhaled budesonide for severe asthma at high altitude]

OBJECTIVE

To determine the benefit of inhaled high dose budesonide combined with terbutaline in patients with severe asthma at high altitude.

METHODS

42 patients with severe asthma at high altitude were assigned in a randomized, double-blind fashion to receive either budesonide combined with terbutaline (budesonide group, 21 cases) or terbutaline with placebo (control group, 21 cases). Both groups received terbutaline delivered by a metered-dose inhaler in a dose of 2.5 mg. Budesonide delivered by a metered-dose inhaler in 1.2 mg in budesonide group and placebo managed by a specially prepared metered-dose inhaler in control group were administered after terbutaline treatment above procedures. Repeated once after 10 min. Before and after therapy, the scores of the activity of accessory respiratory muscles, dyspnea, wheezing (clinical index) and lung function were documented.

RESULTS

At 1, 2, 4, 6 h after therapy, FEV1% [(43 +/- +/- 5)%, (50 +/- 5)%, (57 +/- 5)%, (67 +/- 6)%], PEF% [(47 +/- 5)%, (55 +/- 6)%, (62 +/- 7)%, (69 +/- 7)%], clinical index (5.1 +/- 0.8, 4.3 +/- 0.6, 3.5 +/- 0.6, 2.5 +/- 0.4) in budesonide group and FEV1% [(42 +/- 5)%, (44 +/- 5)%, (45 +/- 5)%, (45 +/- 5)%], PFE% [(46 +/- 5)%, (47 +/- 5)%, (49 +/- 6)%, (49 +/- 6)%], clinical index (5.3 +/- 0.7, 5.0 +/- 0.5, 4.9 +/- 0.7, 4.8 +/- 0.7) in control group were difference markedly compared with before therapy [budesonide group was (35 +/- 5)%, (38 +/- 5)%, 8.3 +/- 1.0, and control group was (33 +/- 5)%, (38 +/- 5)%, 8.3 +/- 1.1, respectively], all (P < 0.01).

CONCLUSIONS

High dose of inhaled budesonide combined with terbutaline should be an effective therapy for patients with severe asthma at high altitude. Budesonide inhaled in high dose produces therapeutic effects as soon as 2 h after therapy.

[A fluorometric method for the determination of norepinephrine in tissue]

This paper reported the determination of norepinephrine (NE) by spectrofluorometry in tissue. The linear relationship between the flecoroscence intensity and the content of NE was in the range of 10-100 ng (lambdaex/lambdaem = 410 nm/505 nm). The rate of recovery is 91.68%-96.64% and RSD (n = 10) is 6.1%. This method is simple, rapid and sensitive.

[Spectrofluorometric determination of corticosterone in plasma and tissue]

Corticosterone is one of the adrenal hormones. This paper reported the determination of corticosterone in plasma and tissue of small mammals with spectrofluorometry. The linear relationship between the fluorescence intensity and the concentration of corticosterone is over the range of 0.01-0.24 microg/mL (lambdaex = 470nm, lambdaem = 525nm). The average rate of standard recovery is 96.0% and RSD (n = 10) is 4.2%. This method is simple, rapid and sensitive.

[Hydride generation-AFS determination of trace arsenic, antimony, selenium and mercury in Chinese herbal medicine in Qinghaixizang plateau]

In this paper, a hydride generation non-dispersive atomic fluorescence spectrometry method has been developed for the determination of trace arsenic, antimony, selenium and mercury in Chinese herbal medicine in Qinghai-Xizang plateau. Under the optimum condition, the quantities of fourteen interference elements are below certain non-interferent limits. The detection limits were as follow (g/mL): As 1.3, Sb 0.39, Se 0.24 and Hg 0.44. The relative standard deviation of 9 determination was As 2.4-4.2%, Sb 2.5-5.6%, Se 3.1-5.0% and Hg 3.8-5.9%. The recovery of four elements was 94.7-105.4%. This method is simple, rapid, sensitive and accurate, and has been successfully tested with As, Sb, Se and Hg in more than 20 kinds of Chinese herbal medicine in Qinghai-Xizang plateau.

Transient expression of uidA constructs in in vitro onion (Allium cepa L.) cultures following particle bombardment and Agrobacterium-mediated DNA delivery

Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient β-glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900-1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient β-glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.

The energetic linkage of GTP hydrolysis and the synthesis of activated sulfate

ATP sulfurylase, from Escherichia coli K-12, catalyzes both the hydrolysis of GTP and the synthesis of activated sulfate (APS). This paper describes the energetic linkage of these reactions and the events that couple them. Steady-state and single-turnover experiments suggest that the binding of GTP inhibits APS production and that the hydrolysis of GTP is required to generate the enzyme form(s) that produces APS. It is this progression from the inhibitory, E-GTP, to the productive, E-GDP, complexes in the cycle of APS synthesis that energetically links these two reactions. This model stands in contrast to other GTPase/target systems in which the binding of GTP alone is sufficient to catalyze multiple turnovers of the target reaction. The stoichiometry of GTP hydrolysis to APS synthesis is 1:1, and equilibrium measurements show that -9.1 kcal/mol, produced by the hydrolysis of GTP, is used to thermodynamically drive production of APS and PPi. These findings establish the mechanism of energy transfer in this novel GTPase/target system, and substantially alter our understanding of the energetics of sulfate activation, an essential step in the metabolic assimilation of sulfur.

The DNA sequence of the sulfate activation locus from Escherichia coli K-12

The DNA sequence of the sulfate activation locus from Escherichia coli K-12 has been determined. The sequence includes the structural genes encoding the enzymes ATP sulfurylase (cysD and cysN) and APS kinase (cysC) which catalyze the synthesis of activated sulfate. These are the only genes known to reside in the sulfate activation operon. Consensus elements of the operon promoter were identified, and the start codons and open reading frames of the Cys polypeptides were determined. During this work, another gene, iap, was partially sequenced and mapped. The activity of ATP sulfurylase is stimulated by an intrinsic GTPase. Comparison of the primary sequences of CysN and Ef-Tu revealed that CysN has conserved many of the residues integral to the three-dimensional structure important for guanine nucleotide binding in Ef-Tu and RAS. nodP and nodQ, from Rhizobium meliloti, are essential for nodulation in leguminous plants. The Cys and Nod proteins are remarkably similar. NodP appears to be the smaller subunit of ATP sulfurylase. NodQ encodes homologues of both CysN and CysC; thus, these enzymes may be covalently associated in R. meliloti. The consensus GTP-binding sequences of NodQ and CysN are identical suggesting that NodQ encodes a regulatory GTPase.

GTPase-mediated activation of ATP sulfurylase

GTP stimulates the synthesis of APS (adenosine 5'-phosphosulfate) by the enzyme ATP sulfurylase (ATP:sulfate adenylyltransferase, EC 2.7.7.4) via a GTPase mechanism. The activation of the enzyme, purified from Escherichia coli, is titratable with GTP. The initial rate of APS formation is increased 116-fold at a saturating concentration of GTP. The enzyme exhibits a GTPase activity that is stimulated by ATP and further enhanced by SO4; however, SO4 alone does not significantly stimulate GTP hydrolysis. The larger subunit of ATP sulfurylase, encoded by cysN, contains a GTP-binding consensus sequence common to other known GTP-binding proteins. This is the first evidence that the sulfate activation pathway is a metabolic target for regulation by a GTPase.