Modifying graphite felt cathode by HNO3 or KOH to improve the degradation efficiency of electro-Fenton for landfill leachate.

Based on graphite felt (GF), the cathode of an electro-Fenton (EF) system was modified by HNO3 and KOH respectively to improve the degradation efficiency for actual landfill leachate. The results of Fourier transform infrared spectroscopy (FTIR) spectra, Boehm titration experiments, contact angle, scanning electron microscopy (SEM) and adsorption experiments illustrated that the surface of the modified GFs had more oxygen-containing functional (OG) groups, and possessed better hydrophilicity and larger specific surface area. In 180 min H2O2 electrogeneration experiments, the cumulative amount of H2O2 produced by unmodified GF (GF-0), HNO3 modified GF (GF-1) and KOH modified GF (GF-2) was 526 mg/L, 891 mg/L and 823 mg/L respectively. In 180 min EF reaction, the removal rate of chemical oxygen demand (COD) in GF-0, GF-1 and GF-2 EF systems was 31.88%, 60.65% and 52.08% respectively; the removal rate of NH4 +-N in GF-0, GF-1 and GF-2 EF systems was 43.37%, 98.10% and 94.81% respectively. In addition, both the performance of GF-1 and GF-2 for Fe2+ regeneration was greatly enhanced, and GF-1 was superior to GF-2. The degradation efficiency for landfill leachate was enhanced obviously by employing the modified EF system, suggesting that the two modified cathodes have great potential in practical production.

Defining Fatty Acid Changes Linked to Rumen Development, Weaning and Growth in Holstein-Friesian Heifers.

After birth, as effectively monogastric animals, calves undergo substantial physiological changes to become ruminants by 3 months of age and reach sexual maturity at approximately 15 months of age. Herein, we assess longitudinal metabolomic changes in Holstein-Friesian (HF) heifers from birth until sexual maturity during this developmental process. Sera from 20 healthy, HF heifers were sampled biweekly from 2 weeks of age until 13 months of age and then monthly until 19 months of age. Sera were assessed using flow infusion electrospray high-resolution mass spectrometry (FIE-HRMS) on a Q Exactive hybrid quadrupole-Orbitrap mass spectrometer for high-throughput, sensitive, non-targeted metabolite fingerprinting. Partial least squares discriminant analysis (PLS-DA) and unsupervised hierarchical clustering analysis (HCA) of the derived metabolomes indicated changes detectable in heifers' sera over time. Time series analyses identified 30 metabolites that could be related to rumen development and weaning at ~3 months of age. Further time series analysis identified 40 metabolites that could be correlated with growth. These findings highlight the role of acetic acid and 3-phenylpropionate (3-PP) in rumen development and growth, suggest that weaning induces elevated levels of fatty acyls in response to a post-weaning stress-induced innate immune response and demonstrate the utilization of fatty acyls in growth. The identified metabolites offer serum metabolites which could inform the nutrition and healthy development of heifers.