Coupling Fe-Co atomic pair to promote the selective reduction of nitroaromatics under mild conditions.

Selectively reducing nitroaromatics into aromatic amines will not only remove nitroaromatic pollutants in waste effluents to reduce environmental risks, but also yield important feedstocks for chemical industrial manufactures. In this study, a FeCo-co-embedded N-doped Carbon (FeCo-N-C) catalyst with Fe-Co atomic pair has been identified with favorable activity, superior selectivity, excellent reusability, as well as outstanding performance in the treatment of real water. The combined results from theoretical study and experimental tests indicate that the improved catalytic performance of FeCo-N-C is owing to the narrowed band gap and electron delocalization caused by the Fe-Co atomic pair which can improve electron transport in its catalytic reaction. The results of isotope experiments and H* quenching experiments confirm that H2O is the source of hydrogen in catalytic reduction of PNP. FeCo-N-C is identified as a superior catalyst to replace multitudinous currently used noble-metal catalysts for the selective catalytic reduction of nitroaromatics in wastewater treatment.

[Association between myocardial connexin 40 and 45 expression and myocardial fibrosis in the rapid atrial pacing canine model].

OBJECTIVE: Electrical and structural remodeling are of importance for the occurrence and maintenance of atrial fibrillation. We observed association between atrial connexin protein expression and fibrosis in a canine model of prolonged rapid atrial pacing. METHODS: "J"-type electrodes were placed in the right atrial appendage under the guidance of X-ray in 16 dogs, Animals in model group (n = 8) received fast pacing (400 beats/min) for 10 weeks while animals in control group (n = 8) maintained at sinus rhythm. Limb-lead ECGs were recorded at 2, 4, 6, 8 weeks respectively. Burst stimulation was applied to induce atrial fibrillation in all animals after 10 weeks, animals were sacrificed thereafter and the left atrial tissues were taken for myocardial collagen measurement (Masson staining) and myocardial ultrastructure examination and detection of protein expression of connexin (Cx) 40 and 45 (immune staining). Procollagen type III N-terminal peptide and type IV collagen in serum were also detected by radioimmunoassay. RESULTS: Two dogs died in model group due to atrial rupture induced cardiac tamponade or lung emboli. Spontaneously atrial fibrillation was not observed in all animals, but two dogs developed atrial flutter and atrial premature beats. Atrial fibrillation was induced by burst stimulation in 4 out of 6 dogs in model group and in none of the dogs in control group. Atrial myocardial collagen volume fraction was significantly increased in model group compared with the control group (P < 0.05). Ultrastructure examination in atrial tissue evidenced disorder, fracture, collagen fiber proliferation, mitochondrial swelling, blurred cristae, and intercalated disc distortion, expansion, part of gap junction disappears in model group. The serum levels of procollagen type III N-terminal peptide and type IV collagen in model group were significantly higher than in the control group (P < 0.05). The protein expression of Cx 40 in atrial myocardium in model group was significantly higher than in control group (P < 0.05), while Cx 45 protein expression was similar between two groups (P > 0.05). The left atrial CVF was positively correlated with Cx 40 (r = 0.671, P < 0.01). CONCLUSION: Increased myocardial fibrosis is positively correlated with upregulation of myocardial Cx 40 protein expression in left atrium in rapid atrial paced canine.

Analysis of a Prophage Gene Frequency Revealed Population Variation of 'Candidatus Liberibacter asiaticus' from Two Citrus-Growing Provinces in China.

Prophages are important genetic elements of bacterial genomes and are involved in lateral gene transfer, pathogenicity, environmental adaptations, and interstrain genetic variability. In this study, the sequence of a prophage terminase gene of 'Candidatus Liberibacter asiaticus', a bacterium associated with citrus Huanglongbing (HLB), was selected as a molecular marker to assess the genetic variation in two 'Ca. L. asiaticus' populations from geographically distinct provinces (Guangdong and Yunnan) in China. The frequency of the prophage terminase gene was 15.8% (19/120) in Guangdong (altitude <500 m) and 97.4% (38/39) in Yunnan (altitude >2,000 m). The difference was highly significant (P < 0.0001) based on χ2 analysis. However, the partial prophage terminase gene sequences obtained from 10 Guangdong strains and 6 Yunnan strains were identical or highly similar, suggesting that at least some bacterial strains in the two locations shared a common recent origin. This is the first report on population variation of 'Ca. L. asiaticus' in China, where HLB was first described. The population variation of 'Ca. L. asiaticus' in the two geographical regions and the related HLB epidemiology were discussed.

[Effects of losartan and simvastatin on collagen content, myocardial expression of MMP-2 mRNA, MMP-9 mRNA and TIMP-1 mRNA, TIMP-2 mRNA in pressure overload rat hearts].

OBJECTIVE: To investigate the effects of simvastatin(Sim) and losartan(Los) on cardiac fibrosis and myocardial expression of MMP-2 mRNA, MMP-9 mRNA and TIMP-1 mRNA, TIMP-2 mRNA in pressure overloaded rat hearts. METHODS: The pressure overload model was induced by descending aortic constriction (DAC) in rats. SD rats were randomized into 6 groups (n = 20 each): normol control group, control sham group, DAC group, Los group (DAC + Los, 5 mg/kg), Sim group (DAC + Sim, 2 mg/kg), Los + Sim group (DAC + Los + Sim, Los 5 mg/kg, Sim 2 mg/kg). Water, Los or Sim drug was administrated by gavage daily beginning from day 5 after operation for 30 days. Collagen was measured on Masson stained myocardial sections, and the level of MMP-2 mRNA, MMP-9 mRNA and TIMP-1 mRNA, TIMP-2 mRNA in left ventricle were detected by RT-PCR. RESULTS: Collagen volume fraction (CVF) in DAC group was significantly higher than the normal control and sham groups (P < 0.01) which could be significantly reduced by Los and Sim (P < 0.05), especially in DAC + Los + Sim group (P < 0.01). The levels of myocardial MMP-2 mRNA, MMP-9 mRNA and TIMP-1 mRNA, TIMP-2 mRNA were also significantly higher in DAC group than in normal control and sham groups (P < 0.01). Treatment Sim and Los alone and especially in combination significantly decreased the TIMP-1 mRNA, TIMP-2 mRNA expressions (P < 0.01) while MMP-2 mRNA, MMP-9 mRNA levels remained unchanged (P > 0.05). CONCLUSION: Upregulation of myocardial MMP-2 mRNA, MMP-9 mRNA and TIMP-1 mRNA, TIMP-2 mRNA expressions might contribute to myocardial fibrosis in this model, Sim and Los significantly inhibited myocardial fibrosis possibly by downregulating myocardial TIMP-1 mRNA, TIMP-2 mRNA expressions in this model.